JP2006226735A - Evaluation method of deterioration of edible oil, and deterioration evaluation device of edible oil - Google Patents

Evaluation method of deterioration of edible oil, and deterioration evaluation device of edible oil Download PDF

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JP2006226735A
JP2006226735A JP2005038472A JP2005038472A JP2006226735A JP 2006226735 A JP2006226735 A JP 2006226735A JP 2005038472 A JP2005038472 A JP 2005038472A JP 2005038472 A JP2005038472 A JP 2005038472A JP 2006226735 A JP2006226735 A JP 2006226735A
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oil
conductivity
test oil
deterioration
temperature
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JP4650828B2 (en
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Yoshio Hagura
義雄 羽倉
Kanichi Suzuki
寛一 鈴木
Yoshihiro Sasaki
芳浩 佐々木
Nobuyuki Kusunoki
信行 楠
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FAMIYU KK
Hiroshima University NUC
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FAMIYU KK
Hiroshima University NUC
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple method, a device or the like capable of evaluating deterioration of an edible oil by acquiring the whole (or a plurality) of indexes (an acid value, a weight object quantity, a chromaticity and a polar compound quantity) on the deterioration of the edible oil, and evaluating the deterioration of the edible oil without taking conditions of a using time and a measuring temperature of the edible oil in consideration. <P>SOLUTION: This invention is based on a knowledge wherein an excellent correlation exists between the inclination of temperature dependency of the conductivity of a test oil and the indexes (the acid value, the weight object quantity, the chromaticity and the polar compound quantity). This evaluation method of the deterioration of the edible oil is characterized by including a process for calculating at least one or more between the acid value, the weight object quantity, the chromaticity and the polar compound quantity from the inclination of the temperature dependency of the conductivity of the test oil, or a process for determining that the test oil cannot be used as an edible oil when the inclination of the temperature dependency of the conductivity of the test oil becomes over a prescribed value. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、食用油の劣化程度を評価する方法、食用油の劣化程度評価装置、および前記食用油の劣化程度評価装置を備えたフライ用器具に関するものである。   The present invention relates to a method for evaluating the degree of deterioration of edible oil, an apparatus for evaluating the degree of deterioration of edible oil, and an instrument for frying provided with the apparatus for evaluating the degree of deterioration of edible oil.

劣化した食用油は、それを用いて揚げたフライ食品の味、香り等の品質面に影響を及ぼすのみならず、当該劣化した食用油を人が摂取することによって胸焼けや吐き気の原因となる場合がある。よって、できるだけ劣化した食用油を使用しないことが好ましいといえる。   Degraded edible oil not only affects the quality and taste of fried foods fried using it, but also causes heartburn and nausea when a person consumes the degraded edible oil There is. Therefore, it can be said that it is preferable not to use edible oil that has deteriorated as much as possible.

食用油の劣化においては、熱酸化、熱重合、熱分解、加水分解などの現象が複合的に起こる。食用油の劣化程度の指標としては、酸価が一般的に用いられているが、酸価では加水分解以外の現象を捉えることはできない。食用油の劣化程度を判断する際に、酸価のみを指標として評価するだけでは、食用油の劣化程度の実際とは異なる、誤った判断をする可能性がある。そのため、一般的に用いられている酸価だけでは不十分で、重合物量や極性化合物量の測定を組み合わせて食用油の劣化程度を判断することが必要であると考えられる(例えば非特許文献1、2参照)。しかし、上記重量物量、極性化合物量を測定するためには、HPLC等のクロマトグラフィーを行なう必要があり、複雑な装置および複雑な操作が必要なこと、測定に際し一定の技量が必要となること、等の不都合がある。   In deterioration of edible oil, phenomena such as thermal oxidation, thermal polymerization, thermal decomposition, and hydrolysis occur in combination. An acid value is generally used as an indicator of the degree of deterioration of edible oil, but phenomena other than hydrolysis cannot be captured by the acid value. When judging the degree of deterioration of edible oil, if only the acid value is evaluated as an index, there is a possibility of making an erroneous determination that is different from the actual degree of deterioration of edible oil. Therefore, it is considered that the acid value generally used alone is not sufficient, and it is necessary to determine the degree of deterioration of edible oil by combining measurement of the amount of polymer and the amount of polar compound (for example, Non-Patent Document 1). 2). However, in order to measure the amount of heavy substances and the amount of polar compounds, it is necessary to perform chromatography such as HPLC, which requires complicated equipment and complicated operations, and requires a certain skill in measurement. There are inconveniences such as.

その他の食用油の劣化程度を評価する指標としては、食用油の色度があるが、食用油の種類によって、その値が異なるため正確な評価を行なうことができない。また、その他の食用油の劣化程度を評価する手段または方法としては、被験油の静電容量から極性化合物量を測定する装置が知られている(非特許文献3参照)。さらに被験油の比オーム抵抗値を指標として揚げ物料理用の油または脂肪の腐敗度を検出する方法が知られている(特許文献1参照)。
特開平7−151722号公報(公開日:平成7年(1995)6月16日) Tyagi VK,Vasishtha AK,Changes in the characteristics and composition of oils during deep-fat frying.,JOURNAL OF THE AMERICAN OIL CHEMISTS’ SOCIETY.,73,499‐506(1996) 藤村 浩嗣他,フライ調理現場における総合的なフライ油管理手法,日本食品科学工学会誌,49,422-427(2002) 株式会社テストー ホームページ、〔平成17年2月1日検索〕、インターネット<http://www.testo.jp/products/08/testo265.html>
Other indexes for evaluating the degree of deterioration of edible oil include the chromaticity of edible oil, but the value varies depending on the type of edible oil, so accurate evaluation cannot be performed. As another means or method for evaluating the degree of deterioration of edible oil, an apparatus for measuring the amount of a polar compound from the capacitance of a test oil is known (see Non-Patent Document 3). Furthermore, a method for detecting the degree of spoilage of fried food oil or fat using the specific ohm resistance value of the test oil as an index is known (see Patent Document 1).
JP-A-7-151722 (Publication date: June 16, 1995) Tyagi VK, Vasishtha AK, Changes in the characteristics and composition of oils during deep-fat frying. , JOURNAL OF THE AMERICAN OIL CHEMISTS 'SOCIETY. 73, 499-506 (1996) Hiromura Fujimura et al., Comprehensive frying oil management method in frying cooking site, Journal of Japan Society for Food Science and Technology, 49, 422-427 (2002) Testo Co., Ltd. Homepage, [Search on February 1, 2005], Internet <http://www.testo.jp/products/08/testo265.html>

非特許文献2に記載の食用油の劣化程度を評価する装置は、極性化合物量のみを測定して評価する手段であり、食用油の劣化程度に関する指標(酸価、重量物量、色度、極性化合物量)を全て(もしくは複数)捕捉して食用油の劣化程度を評価することはできない。よって、食用油の劣化程度を評価する手段としては不十分である。   The apparatus for evaluating the degree of deterioration of edible oil described in Non-Patent Document 2 is a means for measuring and evaluating only the amount of polar compound, and an index (acid value, weight amount, chromaticity, polarity regarding the degree of deterioration of edible oil) It is impossible to evaluate the degree of deterioration of the edible oil by capturing all (or a plurality of) compound amounts). Therefore, it is insufficient as a means for evaluating the degree of deterioration of edible oil.

一方、特許文献1に記載の揚げ物料理用の油または脂肪の腐敗度を検出する方法は、8時間または16時間以上フライに使用した食用油について、食用油の比オーム抵抗(または導電率)と、腐敗度(極脂肪画分または酸価)との相関関係を利用して評価する方法であり、使用から8時間未満の食用油の劣化度の評価には適していない。また比オーム抵抗(または導電率)は温度依存的であるため、比オーム抵抗(または導電率)を指標として食用油の劣化程度を評価するためには、比オーム抵抗(または導電率)の測定温度を考慮する必要がある。したがって、常に一定の測定温度で食用油の比オーム抵抗(または導電率)を測定するか、または測定温度ごとに食用油の比抵抗(または導電率)と、腐敗度(極脂肪画分または酸価)との相関関係を予め検討しておく必要があり、食用油の評価方法としては十分かつ簡便な方法とはなっていない。   On the other hand, the method of detecting the degree of rotting of oil or fat for cooking fried food described in Patent Document 1 is based on the specific ohm resistance (or conductivity) of edible oil for edible oil used for fries for 8 hours or 16 hours or more. This is an evaluation method utilizing the correlation with the degree of spoilage (extreme fat fraction or acid value), and is not suitable for the evaluation of the degree of deterioration of edible oil within 8 hours after use. In addition, since the specific ohm resistance (or conductivity) is temperature dependent, the specific ohm resistance (or conductivity) is measured in order to evaluate the degree of deterioration of edible oil using the specific ohm resistance (or conductivity) as an index. It is necessary to consider the temperature. Therefore, always measure the specific ohm resistance (or conductivity) of edible oil at a constant measurement temperature, or the specific resistance (or conductivity) of edible oil and the degree of spoilage (polar fat fraction or acid at each measurement temperature) In other words, it is not a sufficient and simple method as an edible oil evaluation method.

本発明は、上記問題点に鑑みなされたものであり、食用油の劣化程度に関する指標(酸価、重量物量、色度、極性化合物量)を全て(もしくは複数を)捕捉して食用油の劣化程度を評価することができ、かつ食用油の使用時間、測定温度の諸条件を考慮することなく食用油の劣化程度の評価することができる簡便な方法、装置等を提供することにある。   The present invention has been made in view of the above-mentioned problems, and captures all (or a plurality of) indices (acid value, weight amount, chromaticity, polar compound amount) relating to the degree of deterioration of edible oil, and deterioration of edible oil. It is an object of the present invention to provide a simple method, apparatus, etc. that can evaluate the degree of the edible oil and can evaluate the degree of deterioration of the edible oil without considering various conditions of the edible oil usage time and measurement temperature.

本発明の発明者らは、上記課題を解決すべく鋭意検討を行なったところ、被験油の導電率の温度依存性の傾きと、食用油の劣化程度に関する指標(酸価、重量物量、色度、極性化合物量)との間に良好な相関関係があることを見出した。本発明は、上記新規知見に基づき完成されたものである。   The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems. As a result, the temperature dependency gradient of the conductivity of the test oil and an index relating to the degree of deterioration of the edible oil (acid value, heavy weight, chromaticity) It was found that there is a good correlation with the amount of polar compound). The present invention has been completed based on the above novel findings.

すなわち本発明にかかる食用油の劣化程度の評価方法は、上記課題を解決すべく、被験油の導電率の温度依存性の傾きを、当該被験油の劣化程度の指標として使用する工程を、含むことを特徴としている。   That is, the method for evaluating the degree of deterioration of the edible oil according to the present invention includes the step of using the temperature-dependent slope of the conductivity of the test oil as an indicator of the degree of deterioration of the test oil in order to solve the above problem. It is characterized by that.

また本発明にかかる食用油の劣化程度の評価方法は、上記課題を解決すべく、上記被験油の導電率の温度依存性の傾きを、当該被験油の劣化程度の指標として使用する工程は、被験油の導電率の温度依存性の傾きから、酸価、重量物量、色度および極性化合物量のうち少なくとも1つ以上を算出する工程であることを特徴とするものであってもよい。   The method for evaluating the degree of deterioration of the edible oil according to the present invention uses the slope of the temperature dependence of the conductivity of the test oil as an indicator of the degree of deterioration of the test oil, in order to solve the above problem. It may be characterized in that it is a step of calculating at least one or more of the acid value, the weight amount, the chromaticity and the polar compound amount from the temperature-dependent slope of the conductivity of the test oil.

また本発明にかかる食用油の劣化程度の評価方法は、上記課題を解決すべく、上記被験油の導電率の温度依存性の傾きを、当該被験油の劣化程度の指標として使用する工程は、被験油の導電率の温度依存性の傾きが所定の値以上となった場合に、被験油が食用油として使用不可であると判断する工程であることを特徴とするものであってもよい。   The method for evaluating the degree of deterioration of the edible oil according to the present invention uses the slope of the temperature dependence of the conductivity of the test oil as an indicator of the degree of deterioration of the test oil, in order to solve the above problem. It may be characterized by being a step of determining that the test oil cannot be used as an edible oil when the temperature-dependent slope of the conductivity of the test oil becomes a predetermined value or more.

また本発明にかかる食用油の劣化程度の評価方法は、上記課題を解決すべく、上記構成に加え、少なくとも異なる2点以上の温度における被験油の導電率を測定し、当該被験油の導電率の温度依存性の傾きを算出する工程を、さらに含むことを特徴とするものであってもよい。   Moreover, in order to solve the said subject, the evaluation method of the deterioration degree of the edible oil concerning this invention measures the electrical conductivity of the test oil in two or more different temperatures in addition to the said structure, and the electrical conductivity of the said test oil The method may further include a step of calculating an inclination of the temperature dependence.

また本発明にかかる食用油の劣化程度の評価方法は、上記課題を解決すべく、上記温度が、140℃〜200℃であることを特徴とする構成であってもよい。   Moreover, the structure characterized by the said temperature being 140 degreeC-200 degreeC may be sufficient as the evaluation method of the deterioration degree of the edible oil concerning this invention in order to solve the said subject.

一方、本発明にかかる食用油の劣化程度評価装置は、上記課題を解決すべく、被験油の導電率を測定する導電率測定部、被験油の温度を測定する温度測定部、および被験油の導電率の温度依存性の傾きを計算する計算部を備えることを特徴としている。   On the other hand, the edible oil degradation degree evaluation apparatus according to the present invention includes a conductivity measuring unit that measures the conductivity of the test oil, a temperature measuring unit that measures the temperature of the test oil, and It is characterized by comprising a calculation unit for calculating the gradient of the temperature dependence of the conductivity.

一方、本発明にかかるフライ用器具は、上記食用油の劣化程度評価装置を備えることを特徴としている。   On the other hand, the instrument for frying according to the present invention is characterized by comprising the above-mentioned edible oil deterioration degree evaluation apparatus.

本発明にかかる食用油の劣化程度の評価方法は、被験油の導電率の温度依存性の傾きと、食用油の劣化程度に関する指標(酸価、重量物量、色度、極性化合物量)との間に良好な相関関係があるという知見に基づいて、被験油の導電率の温度依存性の傾きを指標とする評価方法である。それゆえ、食用油の劣化程度に関する指標(酸価、重量物量、色度、極性化合物量)を全て捕捉して、被験油の劣化の程度を評価することができるという効果を奏する。   The method for evaluating the degree of deterioration of the edible oil according to the present invention includes the gradient of the temperature dependence of the conductivity of the test oil and the indices (acid value, weight amount, chromaticity, polar compound amount) relating to the degree of deterioration of the edible oil. Based on the knowledge that there is a good correlation between them, the evaluation method uses the slope of the temperature dependence of the conductivity of the test oil as an index. Therefore, it is possible to capture all the indicators (acid value, weight amount, chromaticity, polar compound amount) relating to the degree of deterioration of the edible oil and evaluate the degree of deterioration of the test oil.

また、導電率の測定温度を考慮した被験油の導電率の温度依存性の傾きを指標としており、導電率の測定温度ごとに標準曲線を作成する必要がなく、さらに劣化の程度を評価するのに好適な被験油の条件(被験油の使用時間)にとらわれることがない。したがって、食用油の劣化程度の評価方法として簡便な方法を提供できるという効果を奏する。   In addition, the slope of the temperature dependence of the conductivity of the test oil taking into account the measured temperature of conductivity is used as an index, so there is no need to create a standard curve for each measured temperature of conductivity, and the degree of deterioration is further evaluated. The test oil conditions (use time of the test oil) suitable for Therefore, there is an effect that a simple method can be provided as a method for evaluating the degree of deterioration of edible oil.

また本発明にかかる食用油の劣化程度評価装置によれば、被験油の導電率および温度を測定し、その測定値から被験油の導電率の温度依存性の傾きを計算することができる。上述の通り、被験油の導電率の温度依存性の傾きと、食用油の劣化程度に関する指標(酸価、重量物量、色度、極性化合物量)との間に良好な相関関係がある。それゆえ本発明にかかる食用油の劣化程度評価装置によれば、被験油の劣化程度を簡便に測定することができるという効果を奏する。   According to the apparatus for evaluating the degree of deterioration of edible oil according to the present invention, the conductivity and temperature of the test oil can be measured, and the temperature-dependent slope of the conductivity of the test oil can be calculated from the measured values. As described above, there is a good correlation between the slope of the temperature dependence of the conductivity of the test oil and the indicators (acid value, weight, chromaticity, polar compound amount) regarding the degree of deterioration of the edible oil. Therefore, according to the edible oil deterioration degree evaluation apparatus according to the present invention, it is possible to easily measure the deterioration degree of the test oil.

また本発明にかかるフライ用器具は、上記本発明にかかる食用油の劣化程度評価装置を備えている。それゆえ、フライに使用している食用油の劣化程度を、フライを行ないながら評価することができ、当該食用油の交換時期を即座に判断することができるという効果を奏する。   Moreover, the instrument for frying concerning this invention is equipped with the deterioration evaluation apparatus of the cooking oil concerning the said invention. Therefore, it is possible to evaluate the degree of deterioration of the edible oil used for frying while performing the frying, and it is possible to immediately determine the replacement time of the edible oil.

本発明の実施の形態について説明すれば、以下のとおりである。なお、本発明はこれに限定されるものではない。   The embodiment of the present invention will be described as follows. Note that the present invention is not limited to this.

<1.本発明にかかる食用油の劣化程度の評価方法>
本発明にかかる食用油の劣化程度の評価方法(以下「本発明の評価方法」という)は、被験油の導電率の温度依存性の傾きを、当該被験油の劣化程度の指標として使用する工程、を含むことを特徴とするものである。これは、被験油の導電率の温度依存性の傾きと、食用油の劣化程度に関する指標(酸価、重量物量、色度、極性化合物量)との間に良好な相関関係があるという知見に基づくものである。以下にかかる相関関係を見出すに至った試験について説示する。
<1. Evaluation Method for Degradation Degree of Edible Oil According to the Present Invention>
The method for evaluating the degree of deterioration of an edible oil according to the present invention (hereinafter referred to as “the method for evaluating the present invention”) uses a slope of the temperature dependence of the conductivity of a test oil as an indicator of the degree of deterioration of the test oil. , Including. This is due to the finding that there is a good correlation between the temperature-dependent slope of the conductivity of the test oil and the indicators (acid value, weight, chromaticity, polar compound amount) regarding the degree of deterioration of the edible oil. Is based. The following describes the tests that led to the finding of such correlations.

なお「食用油」とは、食に供される油脂のことであり、当該油脂には、植物性油脂、動物性油脂がある。植物性油脂としては、パーム油、ナタネ油、ゴマ油、オリーブ油、コーン油、サラダ油等が挙げられ、動物性油脂としては、ラード、牛脂、魚油等が挙げられる。上記食用油には、パルミチン酸、ステアリン酸、オレイン酸、リノール酸、リノレン酸等が含まれている。また「被験油」とは、本は発明の評価方法が適用される食用油のことを意味する。   The “edible oil” refers to fats and oils that are used for food. Examples of the fats and oils include vegetable oils and animal fats. Examples of vegetable oils include palm oil, rapeseed oil, sesame oil, olive oil, corn oil, salad oil and the like, and examples of animal oils include lard, beef tallow, fish oil and the like. The edible oil contains palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid and the like. The “test oil” means an edible oil to which the evaluation method of the present invention is applied.

<1−1.被験油の導電率の温度依存性の傾きと、食用油の劣化程度に関する指標(酸価、重量物量、色度、極性化合物量)との関係>
〔被験油〕
フライ食品の製造に使用した食用油を被験油として用いた。より具体的には、食用油の劣化程度の指標である酸価、重合物量、色度を予め測定した4種類の被験油(F2:学校給食、H1:病院給食、A2:工場給食、A3:工場給食)を使用した。
<1-1. Relationship between the slope of the temperature dependence of the conductivity of the test oil and the indicators (acid value, weight, chromaticity, polar compound amount) regarding the degree of deterioration of the edible oil>
[Test oil]
The edible oil used for the production of the fried food was used as the test oil. More specifically, four types of test oils (F2: school meal, H1: hospital meal, A2: factory meal, A3: pre-measured in acidity, polymer amount, and chromaticity, which are indicators of the degree of deterioration of edible oil) Factory meals) were used.

ここで酸価とは、脂肪、脂肪酸およびろうの1g中に含まれる遊離脂肪酸を中和するのに要する水酸化カリウムのミリグラム数を意味する。酸価は油脂の品位を定める基準の1つとして重要な値で、ことに食用油は酸価が1以下であることを要する。なお酸価の測定は、試料をアルコール−エーテルに溶し、これにフェノールフタレインを指示薬として0.5N水酸化カリウム出て規定することにより行なうことができる。   Here, the acid value means the number of milligrams of potassium hydroxide required to neutralize free fatty acids contained in 1 g of fat, fatty acid and wax. The acid value is an important value as one of the criteria for determining the quality of fats and oils. In particular, the edible oil requires an acid value of 1 or less. The acid value can be measured by dissolving a sample in alcohol-ether, and using 0.5% potassium hydroxide as an indicator with phenolphthalein as an indicator.

また重合物量とは、熱重合により生成した重合物の量を示す指標を意味する。なお重合物量の測定は、HPLCを用いて行なった。簡単には、AOCS標準法(Cd22-91)に準拠し、以下の条件でGPCモードによるHPLC法で測定した。測定はHP-1090SeriesII(Agilent Technologies)、ポリスチレンゲルカラムShodex KF-802(8×300mm)直列2本、示差屈折計(Shodex RI SE-62)、移動相テトラヒドロフラン(流速1ml/min)を用いて室温において行なった。なお、上記重合物量の測定については、非特許文献2の記載を援用することができる。この他、重合物量の分析方法については、例えば[編者 小原 哲二郎、「食用油脂とその加工」、p181-221、建帛社]に記載されている。また食用油の劣化と重合物の関係については、例えば[太田 静行、湯木 悦二 著「改訂 フライ食品の理論と実際」、p40-43、幸書房]記載されている。   The amount of polymer means an index indicating the amount of polymer produced by thermal polymerization. The amount of polymer was measured using HPLC. Briefly, it was measured by the HPLC method in the GPC mode under the following conditions based on the AOCS standard method (Cd22-91). Measurement is performed at room temperature using HP-1090Series II (Agilent Technologies), two polystyrene gel columns Shodex KF-802 (8 x 300 mm) in series, differential refractometer (Shodex RI SE-62), mobile phase tetrahydrofuran (flow rate 1 ml / min) Performed in In addition, about the measurement of the said polymer amount, the description of a nonpatent literature 2 can be used. In addition, a method for analyzing the amount of polymer is described in, for example, [Tetsujiro Ohara, “edible oils and their processing”, p181-221, Kenshisha]. In addition, the relation between the deterioration of edible oil and the polymer is described, for example, [Shiyuki Ota, Junji Yuki, “Revised Fry Food Theory and Practice”, p. 40-43, Koshobo].

一方、色度とは被験油の着色程度を意味する。色度の測定は色差計(ASTM色差計)により行なった。色差計は特に限定されるものではなく、市販品を適宜使用すればよい。   On the other hand, chromaticity means the degree of coloring of the test oil. The chromaticity was measured with a color difference meter (ASTM color difference meter). The color difference meter is not particularly limited, and a commercially available product may be used as appropriate.

被験油の使用日数と劣化程度(酸価、重合物量、色度)との関係を表1に示す。   Table 1 shows the relationship between the days of use of the test oil and the degree of deterioration (acid value, polymer amount, chromaticity).

Figure 2006226735
Figure 2006226735

表1は、左端カラムから順に被験油の名称、被験油の使用日数、被験油のNo.、酸価、重合物量、色度を示している。   Table 1 shows the name of the test oil, the number of days of use of the test oil, the test oil No. in order from the left end column. , Acid value, polymer amount, and chromaticity.

〔試験方法〕
誘電特性(静電容量C、導電率(コンダクタンス)G、抵抗R)の測定には、自作の平行平板電極にLCRメーター(HIOKI社製、3532 LCR HITESTER)を接続した誘電特性測定装置を用いた。当該誘電特性測定装置10の概略を図1に示し、上記自作の平行平板電極20の概略を図2(図2(a)は斜視図、図2(b)上面図)に示す。
〔Test method〕
Dielectric properties (capacitance C, conductivity (conductance) G, resistance R) were measured using a dielectric property measuring device in which an LCR meter (HIOKI, 3532 LCR HITESTER) was connected to a self-made parallel plate electrode. . An outline of the dielectric property measuring apparatus 10 is shown in FIG. 1, and an outline of the self-made parallel plate electrode 20 is shown in FIG. 2 (FIG. 2A is a perspective view and FIG. 2B is a top view).

図1に示すように、誘電特性測定装置10は、概略的に、一対の平行平板電極20を備えたステンレスカップ11、ステンレスカップ11を所定の温度とする温度制御手段12、ステンレスカップ11内の温度を測定する熱電対13、温度制御手段12によって制御可能なヒーター14、LCRメーター15、測定用コンピュータ16とを備えて構成されている。   As shown in FIG. 1, the dielectric characteristic measuring apparatus 10 schematically includes a stainless cup 11 provided with a pair of parallel plate electrodes 20, temperature control means 12 for setting the stainless cup 11 to a predetermined temperature, and the stainless cup 11. A thermocouple 13 for measuring temperature, a heater 14 that can be controlled by the temperature control means 12, an LCR meter 15, and a measuring computer 16 are provided.

図2(a)、(b)に示すように、平行平板電極20は2枚の平板電極21a、21b(縦100mm×横60mm)で構成されており、絶縁体22を介して電極板間距離4mmとなるように固定されている。   As shown in FIGS. 2A and 2B, the parallel plate electrode 20 is composed of two plate electrodes 21 a and 21 b (length 100 mm × width 60 mm), and the distance between the electrode plates via the insulator 22. It is fixed to be 4 mm.

ステンレスカップ11(2L容)に、常温の被験油17(食用油)を1.4L注ぎ、各種測定を行なった。ステンレスカップ11を加熱し、被験油17の温度を140℃、160℃、180℃、200℃に調節し、低温から順に測定を行なった。1分間隔で10回測定を行ない、平均値を測定値として採用した。測定周波数は、1kHzとした。また、各々の測定の際、被験油17(食用油)を注ぐ前に空の状態での空気の静電容量を測定し、以下の(1)式を用いて誘電率を算出した。   1.4L of normal temperature test oil 17 (edible oil) was poured into a stainless steel cup 11 (2 L capacity), and various measurements were performed. The stainless steel cup 11 was heated, the temperature of the test oil 17 was adjusted to 140 ° C., 160 ° C., 180 ° C., and 200 ° C., and measurements were performed in order from the lowest temperature. Measurement was performed 10 times at 1 minute intervals, and the average value was adopted as the measurement value. The measurement frequency was 1 kHz. Moreover, before each test oil 17 (edible oil) was poured in each measurement, the capacitance of air in an empty state was measured, and the dielectric constant was calculated using the following equation (1).

Figure 2006226735
Figure 2006226735

なおこのLCRメーター15は測定周波数が42Hz〜5MHzの範囲で測定が可能である。また測定用コンピュータ16によりLCRメーター15を制御して試料の誘電特性を記録した。   The LCR meter 15 can measure at a measurement frequency in the range of 42 Hz to 5 MHz. Further, the dielectric property of the sample was recorded by controlling the LCR meter 15 with the measuring computer 16.

〔結果及び考察〕
(A)被験油の誘電率または導電率と、温度との関係
各被験油(食用油)の温度と誘電率との関係を図3、4、5、6に示した。図3は被験油F2の結果を示し、図4は被験油H1の結果を示し、図5は被験油A2の結果を示し、図6は被験油A3の結果を示した。なお図中のシンボルに対応するそれぞれの被験油No.は、表1に示す被験油No.と一致しており、表1を参照することにより被験油を把握することができる。図3〜6より、誘電率は温度上昇に伴い概ね減少する傾向が見られた。しかし、一部の被験油(F2-3,F2-4、H1-3、A2-10、A3-8)では、温度上昇に伴い誘電率が増加する傾向を示した。
[Results and discussion]
(A) Relationship between Dielectric Constant or Conductivity of Test Oil and Temperature The relationship between the temperature and dielectric constant of each test oil (edible oil) is shown in FIGS. FIG. 3 shows the result of test oil F2, FIG. 4 shows the result of test oil H1, FIG. 5 shows the result of test oil A2, and FIG. 6 shows the result of test oil A3. Each test oil No. corresponding to the symbol in the figure. Is the test oil No. shown in Table 1. The test oil can be grasped by referring to Table 1. As shown in FIGS. 3 to 6, the dielectric constant tended to decrease with increasing temperature. However, some of the test oils (F2-3, F2-4, H1-3, A2-10, A3-8) tended to increase the dielectric constant with increasing temperature.

一方、各被験油の温度と導電率(コンダクタンス)との関係を図7、8、9、10に示した。図7は被験油F2の結果を示し、図8は被験油H1の結果を示し、図9は被験油A2の結果を示し、図10は被験油A3の結果を示した。なお図中のシンボルに対応するそれぞれの被験油No.は、表1に示す被験油No.と一致しており、表1を参照することにより被験油を把握することができる。温度変化に伴い導電率(コンダクタンス)は直線的に変化した。また、被験油の使用日数が増加するに従い、直線の傾きが大きくなる傾向が見られた。よって被験油の劣化程度が導電率(コンダクタンス)の温度依存性に影響を及ぼすことが分かった。   On the other hand, the relationship between the temperature of each test oil and the conductivity (conductance) is shown in FIGS. FIG. 7 shows the result of test oil F2, FIG. 8 shows the result of test oil H1, FIG. 9 shows the result of test oil A2, and FIG. 10 shows the result of test oil A3. Each test oil No. corresponding to the symbol in the figure. Is the test oil No. shown in Table 1. The test oil can be grasped by referring to Table 1. The electrical conductivity (conductance) changed linearly with the temperature change. In addition, the slope of the straight line tended to increase as the number of days of use of the test oil increased. Therefore, it was found that the degree of deterioration of the test oil affects the temperature dependence of the conductivity (conductance).

被験油の誘電率と導電率(コンダクタンス)には温度依存性があった。従って、誘電率または導電率(コンダクタンス)を利用してフライ油の劣化程度を判定する場合には、誘電率または導電率(コンダクタンス)の温度依存性を考慮する必要があることが明らかとなった。   The dielectric constant and conductivity of the test oil were temperature dependent. Therefore, when determining the degree of deterioration of frying oil using the dielectric constant or conductivity (conductance), it became clear that the temperature dependence of the dielectric constant or conductivity (conductance) must be considered. .

(B)被験油の劣化程度と誘電率または導電率との関係
各被験油の劣化程度と誘電率との関係を、図11、12、13、14に示した。図11は被験油F2の結果を示し、図12は被験油H1の結果を示し、図13は被験油A2の結果を示し、図13は被験油A3の結果を示した。また図11(a)は酸価と誘電率との関係を示し、図11(b)は重量物量と誘電率との関係を示し、図11(c)は色度と誘電率の関係を示す(図12、13、14において同じ)。図11〜14の結果より、被験油の劣化程度が増加するに従い誘電率も増加するということが分かった。
(B) Relationship between degree of deterioration of test oil and dielectric constant or conductivity The relationship between the degree of deterioration of each test oil and the dielectric constant is shown in FIGS. FIG. 11 shows the result of test oil F2, FIG. 12 shows the result of test oil H1, FIG. 13 shows the result of test oil A2, and FIG. 13 shows the result of test oil A3. 11A shows the relationship between the acid value and the dielectric constant, FIG. 11B shows the relationship between the weight amount and the dielectric constant, and FIG. 11C shows the relationship between the chromaticity and the dielectric constant. (Same in FIGS. 12, 13, and 14). From the results of FIGS. 11 to 14, it was found that the dielectric constant increases as the degree of deterioration of the test oil increases.

一方、各被験油の劣化程度と導電率(コンダクタンス)との関係を図15、16、17、18に示した。図15は被験油F2の結果を示し、図16は被験油H1の結果を示し、図17は被験油A2の結果を示し、図18は被験油A3の結果を示した。また図15(a)は酸価と導電率との関係を示し、図15(b)は重量物量と導電率との関係を示し、図15(c)は色度と導電率の関係を示す(図16、17、18において同じ)。図15〜18の結果より、誘電率と同様に被験油の劣化程度が増加するに従い、導電率(コンダクタンス)も増加する傾向を示した。また、フライ油の劣化程度と導電率(コンダクタンス)との間には良好な相関関係が見られた。   On the other hand, the relationship between the degree of deterioration of each test oil and the conductivity (conductance) is shown in FIGS. FIG. 15 shows the result of test oil F2, FIG. 16 shows the result of test oil H1, FIG. 17 shows the result of test oil A2, and FIG. 18 shows the result of test oil A3. 15A shows the relationship between the acid value and the conductivity, FIG. 15B shows the relationship between the weight amount and the conductivity, and FIG. 15C shows the relationship between the chromaticity and the conductivity. (Same in FIGS. 16, 17, and 18). From the results of FIGS. 15 to 18, the conductivity (conductance) tended to increase as the degree of deterioration of the test oil increased as well as the dielectric constant. In addition, a good correlation was found between the degree of deterioration of the frying oil and the electrical conductivity (conductance).

各温度における被験油の劣化程度と誘電率または導電率との間の相関係数R2を図11〜18から求め、表2、3、4、5に示した。 The correlation coefficient R 2 between the degree of deterioration of the test oil at each temperature and the dielectric constant or conductivity was obtained from FIGS. 11 to 18 and shown in Tables 2, 3, 4, and 5.

Figure 2006226735
Figure 2006226735

Figure 2006226735
Figure 2006226735

Figure 2006226735
Figure 2006226735

Figure 2006226735
Figure 2006226735

表2〜5より、誘電率と導電率(コンダクタンス)を比較した場合、全体的な傾向として、導電率(コンダクタンス)は誘電率よりも良好な相関係数を示すことが明らかとなった。このフライ油の劣化程度とフライ油の導電率(コンダクタンス)との対応関係をより詳細に計測することで、フライ油の導電率(コンダクタンス)をフライ油の劣化程度の指標として利用可能であるということが分かった。したがって、導電率(コンダクタンス)がフライ油の劣化程度の把握に適していることが分かった。   From Tables 2 to 5, it was clarified that when the dielectric constant and the conductivity (conductance) are compared, the conductivity (conductance) shows a better correlation coefficient than the dielectric constant as an overall tendency. By measuring in more detail the correspondence between the degree of deterioration of this frying oil and the conductivity (conductance) of the frying oil, the conductivity (conductance) of the frying oil can be used as an indicator of the degree of deterioration of the frying oil. I understood that. Therefore, it was found that the conductivity (conductance) is suitable for grasping the degree of deterioration of the frying oil.

(C)導電率(コンダクタンス)の温度依存性を利用した試験結果の解析
図7〜10において、被験油の劣化程度との間に関連性が示唆された導電率(コンダクタンス)の温度依存性について検討を行なった。全ての被験油における温度と導電率(コンダクタンス)との関係を図19に示した。なお図中のシンボルに対応するそれぞれの被験油No.は、表1に示す被験油No.と一致しており、表1を参照することにより被験油を把握することができる。図7〜10と同様に、被験油の使用日数が増加するに従い直線の傾きが大きくなることが明らかとなった。すなわち、被験油の劣化程度が導電率(コンダクタンス)の温度依存性に影響を及ぼすことを図7〜10及び図19は示している。図7〜10及び図19から導電率(コンダクタンス)の温度依存性の傾き(以下、適宜「dG/dT」で示す)、すなわち図7〜10および図19における直線の傾きを求め、当該dG/dTと被験油の劣化程度(酸価、重合物量、色度)との関係を、図20、21、22、23、24、および25に示した。図20は被験油F2の結果を示し、図21は被験油H1の結果を示し、図22は被験油A2の結果を示し、図23は被験油A3の結果を示した。また図24は全ての被験油とdG/dTとの関係を示した。なお図20(a)は酸価とdG/dTとの関係を示し、図20(b)は重量物量とdG/dTとの関係を示し、図20(c)は色度とdG/dTの関係を示す(図21、22、23、および24において同じ)。
(C) Analysis of test result using temperature dependence of conductivity (conductance) In FIGS. 7 to 10, the temperature dependence of conductivity (conductance) suggested to be related to the degree of deterioration of the test oil A study was conducted. The relationship between temperature and conductivity (conductance) in all test oils is shown in FIG. Each test oil No. corresponding to the symbol in the figure. Is the test oil No. shown in Table 1. The test oil can be grasped by referring to Table 1. As in FIGS. 7 to 10, it became clear that the slope of the straight line increases as the number of days of use of the test oil increases. That is, FIGS. 7 to 10 and FIG. 19 show that the degree of deterioration of the test oil affects the temperature dependence of the conductivity (conductance). The gradient of the temperature dependence of the conductivity (conductance) (hereinafter referred to as “dG / dT” where appropriate), that is, the slope of the straight line in FIGS. 7 to 10 and 19 is obtained from FIGS. FIGS. 20, 21, 22, 23, 24, and 25 show the relationship between dT and the degree of deterioration of the test oil (acid value, polymer content, chromaticity). 20 shows the result of test oil F2, FIG. 21 shows the result of test oil H1, FIG. 22 shows the result of test oil A2, and FIG. 23 shows the result of test oil A3. FIG. 24 shows the relationship between all test oils and dG / dT. 20A shows the relationship between the acid value and dG / dT, FIG. 20B shows the relationship between the weight amount and dG / dT, and FIG. 20C shows the relationship between chromaticity and dG / dT. The relationship is shown (same in FIGS. 21, 22, 23, and 24).

図20〜24の結果より、被験油の劣化程度と導電率(コンダクタンス)の温度依存性の傾き(dG/dT)との間には良好な相関関係があることが明らかとなった。具体的には、図20(a)の結果から、被験油F2に関し、dG/dTと酸価との相関係数Rは0.971であり、このときの直線回帰式は、Y=0.0000000002029X+0.0000000001038であった。また、図20(b)の結果から、被験油F2に関し、dG/dTと重合物量との相関係数Rは0.9774であり、このときの直線回帰式は、Y=0.0000000001183X−0.0000000000184であった。また、図20(c)の結果から、被験油F2に関し、dG/dTと色度との相関係数Rは0.9562であり、このときの直線回帰式は、Y=0.0000000000063X+0.0000000001100であった。 From the results of FIGS. 20 to 24, it has been clarified that there is a good correlation between the degree of deterioration of the test oil and the gradient (dG / dT) of the temperature dependency of the conductivity (conductance). Specifically, from the results of FIG. 20 (a), relates to a test oil F2, the correlation coefficient R 2 between the dG / dT and the acid value was 0.971, linear regression equation of this time, Y = 0.0000000002029 X + 0.0000000001038. From the results of FIG. 20 (b), the relates test oil F2, the correlation coefficient R 2 between the polymerization amount and dG / dT is 0.9774, linear regression equation of this time, Y = 0.0000000001183X-0.0000000000184 Met. From the results of FIG. 20 (c), the relates test oil F2, the correlation coefficient R 2 between the dG / dT and the chromaticity is 0.9562, linear regression equation of this time, Y = 0.0000000000063X + 0.0000000001100 Met.

また図21(a)の結果から、被験油H1に関し、dG/dTと酸価との相関係数Rは0.9973であり、このときの直線回帰式は、Y=0.0000000013080X+0.0000000000227であった。また、図21(b)の結果から、被験油H1に関し、dG/dTと重合物量との相関係数Rは0.9513であり、このときの直線回帰式は、Y=0.0000000001367X−0.0000000000583であった。また、図21(c)の結果から、被験油H1に関し、dG/dTと色度との相関係数Rは0.9525であり、このときの直線回帰式は、Y=0.0000000000128X+0.0000000000277であった。 Also from the results of FIG. 21 (a), the relates test oil H1, the correlation coefficient R 2 between the dG / dT and the acid value was 0.9973, linear regression equation of this case is the Y = 0.0000000013080X + 0.0000000000227 there were. From the results of FIG. 21 (b), the relates test oil H1, the correlation coefficient R 2 between the polymerization amount and dG / dT is 0.9513, linear regression equation of this time, Y = 0.0000000001367X-0.0000000000583 Met. From the results of FIG. 21 (c), the relates test oil H1, the correlation coefficient R 2 between the dG / dT and the chromaticity is 0.9525, linear regression equation of this time, Y = 0.0000000000128X + 0.0000000000277 Met.

また図22(a)の結果から、被験油A2に関し、dG/dTと酸価との相関係数Rは0.9963であり、このときの直線回帰式は、Y=0.0000000005942X−0.0000000000057であった。また、図22(b)の結果から、被験油A2に関し、dG/dTと重合物量との相関係数Rは0.9781であり、このときの直線回帰式は、Y=0.0000000001956X−0.0000000003132であった。また、図21(c)の結果から、被験油A2に関し、dG/dTと色度との相関係数Rは0.9959であり、このときの直線回帰式は、Y=0.0000000000091X+0.0000000000069であった。 The results in FIG. 22 (a), relates to a test oil A2, the correlation coefficient R 2 between the dG / dT and the acid value was 0.9963, linear regression equation of this case is the Y = 0.0000000005942X-0.0000000000057 there were. From the results of FIG. 22 (b), the relates test oil A2, the correlation coefficient R 2 between the polymerization amount and dG / dT is 0.9781, linear regression equation of this time, Y = 0.0000000001956X-0.0000000003132 Met. From the results of FIG. 21 (c), the relates test oil A2, the correlation coefficient R 2 between the dG / dT and the chromaticity is 0.9959, linear regression equation of this time, Y = 0.0000000000091X + 0.0000000000069 Met.

また図23(a)の結果から、被験油A3に関し、dG/dTと酸価との相関係数Rは0.9957であり、このときの直線回帰式は、Y=0.0000000004632X−0.0000000000246であった。また、図23(b)の結果から、被験油A3に関し、dG/dTと重合物量との相関係数Rは0.9613であり、このときの直線回帰式は、Y=0.0000000001235X−0.0000000002182であった。また、図23(c)の結果から、被験油A3に関し、dG/dTと色度との相関係数Rは0.9984であり、このときの直線回帰式は、Y=0.0000000000058X+0.0000000000034であった。 Also from the results of FIG. 23 (a), relates to a test oil A3, the correlation coefficient R 2 between the dG / dT and the acid value was 0.9957, linear regression equation of this case is the Y = 0.0000000004632X-0.0000000000246 there were. From the results of FIG. 23 (b), the relates test oils A3, the correlation coefficient R 2 between the polymerization amount and dG / dT is 0.9613, linear regression equation of this time, Y = 0.0000000001235X-0.0000000002182 Met. From the results of FIG. 23 (c), the relates test oils A3, the correlation coefficient R 2 between the dG / dT and the chromaticity is 0.9984, linear regression equation of this time, Y = 0.0000000000058X + 0.0000000000034 Met.

さらに図24(a)の結果から、全ての被験油に関し、dG/dTと酸価との相関係数Rは0.7965であり、このときの直線回帰式は、Y=0.0000000003856X+0.0000000000274であった。また、図24(b)の結果から、全ての被験油に関し、dG/dTと重合物量との相関係数Rは0.8686であり、このときの直線回帰式は、Y=0.0000000001457X−0.0000000001860であった。また、図24(c)の結果から、全ての被験油に関し、dG/dTと色度との相関係数Rは0.9232であり、このときの直線回帰式は、Y=0.0000000000072X+0.0000000000334であった。 Further from the results of FIG. 24 (a), the For all test oils, the correlation coefficient R 2 between the dG / dT and the acid value was 0.7965, linear regression equation of this time, Y = 0.0000000003856X + 0.0000000000274 Met. From the results of FIG. 24 (b), the For all test oils, the correlation coefficient R 2 between the polymerization amount and dG / dT is 0.8686, linear regression equation of this time, Y = 0.0000000001457X- It was 0.0000000001860. From the results of FIG. 24 (c), the For all test oils, the correlation coefficient R 2 between the dG / dT and the chromaticity is 0.9232, linear regression equation of this time, Y = 0.0000000000072X + 0. It was 0000000000334.

今回試験に用いた被験油(F2、H1、A2、A3)は、油の種類、使用方法、使用条件等が異なるにも関わらず、図24に示すように、被験油の劣化程度と導電率(コンダクタンス)の温度依存性の傾き(dG/dT)との間に良好な相関関係を示した。したがって、被験油種類に関係なくdG/dTを求めることによって、当該被験油の劣化程度を評価することができるということがわかった。   Although the test oils (F2, H1, A2, A3) used in this test were different in oil type, usage method, usage conditions, etc., as shown in FIG. A good correlation was exhibited with the temperature-dependent slope (dG / dT) of (conductance). Therefore, it was found that the degree of deterioration of the test oil can be evaluated by determining dG / dT regardless of the type of test oil.

<1−2.本発明の評価方法の実施形態>
(D)導電率(コンダクタンス)の温度依存性の傾き(dG/dT)の把握
本発明の評価方法は既述のとおり、導電率(コンダクタンス)の温度依存性の傾き(dG/dT)を指標として使用し、被験油の劣化程度を評価するため、本発明の評価方法を実施する際には、まず被験油の導電率、および導電率測定時の被験油の温度を測定する必要がある。被験油の導電率の測定は、公知のテスター(導通試験機)を用いて測定すればよい。ただし、被験油は抵抗が極めて高いために、油の導電率を測定することができるテスターを適宜選択の上、適用する必要がある。例えば、上記図1に示した誘電特性測定装置は、被験油の導電率の測定に利用可能である。また被験油の温度測定は、公知の温度計、サーモセンサーを用いればよい。
<1-2. Embodiment of Evaluation Method of the Present Invention>
(D) Grasping of temperature dependency gradient (dG / dT) of conductivity (conductance) As described above, the evaluation method of the present invention uses the temperature dependency gradient (dG / dT) of conductivity (conductance) as an index. In order to evaluate the degree of deterioration of the test oil, it is necessary to first measure the conductivity of the test oil and the temperature of the test oil when measuring the conductivity. What is necessary is just to measure the electrical conductivity of test oil using a well-known tester (continuity test machine). However, since the test oil has extremely high resistance, it is necessary to select and apply a tester that can measure the conductivity of the oil as appropriate. For example, the dielectric property measuring apparatus shown in FIG. 1 can be used for measuring the conductivity of the test oil. The temperature of the test oil may be measured using a known thermometer or thermosensor.

本発明の評価方法は、導電率(コンダクタンス)の温度依存性の傾き(dG/dT)を指標とするために、少なくとも異なる2点以上の温度において、被験油の導電率を測定することが好ましい。このように、異なる温度において少なくとも2点の導電率の値があれば、導電率と温度との関係を示す直線が引け、その直線の回帰式からdG/dTを算出することができる。ただし、導電率の測定は異なる温度において、可能な限り多く測定することが好ましい。さらに、同一の温度においても複数回、導電率を測定しておくことが好ましい。導電率と温度との関係を示す直線の精度を向上させることが可能となり、本発明の評価方法による劣化程度の評価の精度が向上するからである。なおdG/dTは、測定温度とその温度における導電率(コンダクタンス)との関係を示す直線回帰式を最小二乗法等で計算すればよい。   The evaluation method of the present invention preferably measures the conductivity of the test oil at at least two different temperatures in order to use the temperature-dependent slope (dG / dT) of conductivity (conductance) as an index. . Thus, if there are at least two conductivity values at different temperatures, a straight line indicating the relationship between the conductivity and temperature can be drawn, and dG / dT can be calculated from the regression equation of the straight line. However, the conductivity is preferably measured as much as possible at different temperatures. Furthermore, it is preferable to measure the conductivity several times even at the same temperature. This is because it is possible to improve the accuracy of the straight line indicating the relationship between the conductivity and the temperature, and the accuracy of the evaluation of the degree of deterioration by the evaluation method of the present invention is improved. For dG / dT, a linear regression equation indicating the relationship between the measured temperature and the conductivity (conductance) at that temperature may be calculated by the least square method or the like.

また、被験油の導電率を測定する温度は特に限定されるものではないが、実施にフライを行なう温度であること、劣化程度と導電率との相関が高いことを考慮すれば、140℃以上200℃以下が好ましく、160℃以上180℃以下がさらに好ましい。   Further, the temperature at which the conductivity of the test oil is measured is not particularly limited, but it is 140 ° C. or higher in consideration of the fact that it is a temperature at which frying is carried out and that the degree of deterioration and the conductivity are highly correlated. It is preferably 200 ° C. or lower, and more preferably 160 ° C. or higher and 180 ° C. or lower.

(E)導電率(コンダクタンス)の温度依存性の傾き(dG/dT)を用いた被験油の劣化度の評価
本発明の評価方法に含まれる被験油の温度依存性の傾き(dG/dT)を、被験油の劣化程度の指標として使用する工程は、特に限定されるものではないが、例えば、被験油の導電率の温度依存性の傾き(dG/dT)から、酸価、重量物量および色度のうち少なくとも1つ以上を算出する工程であることが挙げられる。
(E) Evaluation of deterioration degree of test oil using temperature dependency gradient (dG / dT) of conductivity (conductance) Temperature dependency gradient (dG / dT) of test oil included in the evaluation method of the present invention Is not particularly limited, for example, from the slope of temperature dependence of the conductivity of the test oil (dG / dT), the acid value, the weight amount and It is mentioned that it is the process of calculating at least 1 or more among chromaticity.

被験油の導電率の温度依存性の傾き(dG/dT)と、酸価、重量物量、または色度との関係を示す標準曲線を予め作成しておき、上記(D)によって把握した被験油の温度依存性の傾き(dG/dT)を、酸価、重量物量、または色度についての各標準曲線に当てはめ、酸価、重量物量、または色度を算出すればよい。こうのようにして算出した酸価、重量物量、または色度が、酸価、重量物、または色度についての限界値(食用油として使用不可であるというの所定の値)以上となった時に、当該被験油は食用油として使用不可であると判断することができる。   A standard curve showing the relationship between the temperature-dependent slope (dG / dT) of the conductivity of the test oil and the acid value, the weight, or the chromaticity is prepared in advance, and the test oil grasped by the above (D) The temperature dependence slope (dG / dT) is applied to each standard curve for acid value, weight amount, or chromaticity to calculate the acid value, weight amount, or chromaticity. When the acid value, weight amount, or chromaticity calculated in this way is equal to or greater than the limit value (predetermined value that it cannot be used as an edible oil) for the acid value, weight, or chromaticity It can be determined that the test oil cannot be used as an edible oil.

なお上記各標準曲線は、被験油と同種の食用油について、上記<1−1>の項において説示した操作を行なって作成しておくことが、評価の精度を向上するために好ましいといえる。しかし、図24について上記<1−1>の項で説示したごとく、図24に示した標準曲線は種々広範な食用油に適用可能であるということが分かっているため、図24に示した各標準曲線を利用して、被験油の酸価、重量物量、または色度を算出してもよい。   In addition, it can be said that each said standard curve is preferable in order to improve the precision of evaluation, performing the operation demonstrated in the item of the above <1-1> about the same kind of edible oil as a test oil. However, as explained in the section <1-1> above with respect to FIG. 24, it is known that the standard curve shown in FIG. 24 can be applied to a wide variety of edible oils. A standard curve may be used to calculate the acid value, weight, or chromaticity of the test oil.

また、本発明の評価方法に含まれる被験油の温度依存性の傾き(dG/dT)を、被験油の劣化程度の指標として使用する工程は、被験油の導電率の温度依存性の傾きが所定の値以上となった場合に、被験油が食用油として使用不可であると判断する工程であってもよい。酸価、重量物、または色度についての限界値(食用油として使用不可であるというの所定の値)を、被験油の導電率の温度依存性の傾き(dG/dT)と、酸価、重量物量、または色度との関係を示す標準曲線を用いて換算すれば、被験油の導電率の温度依存性の傾き(dG/dT)の限界値を求めることができる。したがって、被験油の導電率の温度依存性の傾き(dG/dT)が、被験油の限界値以上となった時に当該被験油は、食用油として使用不可であると判断すればよい。   In addition, the step of using the temperature dependency gradient (dG / dT) of the test oil included in the evaluation method of the present invention as an index of the degree of deterioration of the test oil is such that the temperature dependency gradient of the conductivity of the test oil is It may be a step of determining that the test oil cannot be used as an edible oil when the predetermined value or more is reached. The limit value for acid value, weight, or chromaticity (predetermined value that it cannot be used as an edible oil), temperature-dependent slope of conductivity of test oil (dG / dT), acid value, When converted using a standard curve indicating the relationship with the weight amount or chromaticity, the limit value of the gradient (dG / dT) of the temperature dependence of the conductivity of the test oil can be obtained. Therefore, when the temperature-dependent slope (dG / dT) of the conductivity of the test oil becomes equal to or greater than the limit value of the test oil, it may be determined that the test oil cannot be used as an edible oil.

なお、酸価、または重量物量についての限界値(食用油として使用不可であるというの所定の値)は適宜設定すればよいが、一般的には酸価の限界値は2.5(mgKOH/g)〜3.0(mgKOH/g)、重合物量の限界値は10(%)〜12(%)である。なお限界値は、上記値に限定されるものではない。   The limit value for the acid value or the weight amount (predetermined value that it cannot be used as an edible oil) may be set as appropriate. In general, the limit value of the acid value is 2.5 (mgKOH / g) to 3.0 (mg KOH / g), and the limit value of the polymer amount is 10 (%) to 12 (%). The limit value is not limited to the above value.

なお導電率と抵抗は互いに逆数の関係にあるため、上記説示した導電率を抵抗に置き換えることを当業者は容易に理解する。   In addition, since electrical conductivity and resistance have a reciprocal relationship, those skilled in the art can easily understand that the above-described electrical conductivity is replaced by resistance.

また、極性化合物量は、重合物量との間に良好な相関関係があり、予め求めた極性化合物量と重量物量との相関関係から計算することができる値である。よって導電率(コンダクタンス)の温度依存性の傾き(dG/dT)と相関関係があることは明らかである。したがって、導電率(コンダクタンス)の温度依存性の傾き(dG/dT)から、極性化合物量を算出することは可能である。食用油が劣化すると、極性を持った種々の物質(分解性生物、重合物、遊離脂肪酸など)が生じる。すなわち「極性化合物量」とは、トリグリセライド以外の形状となった物質の総量であり、食用油の劣化程度の指標の1つである。   Moreover, the amount of polar compounds has a good correlation with the amount of polymer, and is a value that can be calculated from the correlation between the amount of polar compound determined in advance and the amount of weight. Therefore, it is clear that there is a correlation with the temperature dependence gradient (dG / dT) of the conductivity (conductance). Therefore, it is possible to calculate the amount of polar compound from the gradient (dG / dT) of the temperature dependence of the conductivity (conductance). When edible oil deteriorates, various substances with polarity (degradable organisms, polymers, free fatty acids, etc.) are produced. That is, the “polar compound amount” is the total amount of substances having a shape other than triglyceride, and is one of the indicators of the degree of deterioration of edible oil.

<2.本発明にかかる食用油の劣化程度評価装置およびフライ用器具>
本発明にかかる食用油の劣化程度評価装置(以下「本発明の評価装置」という)は、被験油の導電率を測定する導電率測定部、被験油の温度を測定する温度測定部、および被験油の導電率の温度依存性の傾きを計算する計算部を備えることを特徴としている。
<2. Deterioration degree evaluation apparatus for edible oil and fry appliance according to the present invention>
An edible oil deterioration degree evaluation apparatus according to the present invention (hereinafter referred to as “evaluation apparatus of the present invention”) includes a conductivity measurement unit that measures the conductivity of a test oil, a temperature measurement unit that measures the temperature of the test oil, and a test It is characterized by including a calculation unit that calculates the temperature-dependent slope of the conductivity of oil.

図25に本発明の評価装置の一例のブロック図を示す。   FIG. 25 shows a block diagram of an example of the evaluation apparatus of the present invention.

当該本発明の評価装置30は、導電率測定部31、温度測定部32、制御部33、および表示部34を有している。なお制御部33は測定制御部33a、温度制御部33b、および計算部33cで構成されている。   The evaluation device 30 of the present invention includes a conductivity measuring unit 31, a temperature measuring unit 32, a control unit 33, and a display unit. The control unit 33 includes a measurement control unit 33a, a temperature control unit 33b, and a calculation unit 33c.

導電率測定部31は、測定制御部33aからの電気信号を受けて被験油の導電率の測定を行なう。そして、その測定データを計算部33cへ電気信号として送る。当該導電率測定部31は、例えば公知のテスターにより構成されている。   The conductivity measuring unit 31 receives the electric signal from the measurement control unit 33a and measures the conductivity of the test oil. Then, the measurement data is sent as an electrical signal to the calculation unit 33c. The conductivity measuring unit 31 is constituted by, for example, a known tester.

また温度測定部32は、測定制御部33aからの電気信号を受けて被験油の温度の測定を行なう。そして、その測定データを計算部33c、温度制御部33bへ電気信号として送る。当該温度測定部32は、例えば公知のサーモセンサーにより構成されている。   Moreover, the temperature measurement part 32 receives the electric signal from the measurement control part 33a, and measures the temperature of test oil. Then, the measurement data is sent as an electrical signal to the calculation unit 33c and the temperature control unit 33b. The said temperature measurement part 32 is comprised by the well-known thermo sensor, for example.

測定制御部33aは、導電率測定部31および温度測定部32に対して、導電率および温度の測定を、ほぼ同時に行なうように制御する。また、測定制御部33aは少なくとも異なる2点以上の温度において導電率および温度の測定を行なうように制御する。なお導電率および温度の測定は、断続的に行なってもよいし、連続的に行なってもよい。   The measurement control unit 33a controls the conductivity measurement unit 31 and the temperature measurement unit 32 so that the measurement of the conductivity and temperature is performed almost simultaneously. Further, the measurement control unit 33a performs control so that the conductivity and temperature are measured at at least two different temperatures. Note that the conductivity and temperature may be measured intermittently or continuously.

温度制御部33bは、温度測定部32からの測定データを受け、被験油を固定するための被験油固定部(図示せず)に備えられた加熱部(図示せず)を制御して、被験油の所定の温度となるように制御を行なう。なお当該被験油固定部は、劣化程度を評価する被験油を所定量注入できるようになっている。   The temperature control unit 33b receives measurement data from the temperature measurement unit 32, and controls a heating unit (not shown) provided in a test oil fixing unit (not shown) for fixing the test oil. Control is performed so that the oil reaches a predetermined temperature. In addition, the said test oil fixing | fixed part can inject | pour a predetermined amount of test oil which evaluates a deterioration degree.

計算部33cは、インストールされているプログラムにより、導電率測定部31および温度測定部32からの測定データをもとに被験油の導電率の温度依存性の傾き(dG/dT)を計算することができる。またdG/dTから被験油の酸価、重合物量、色度、極性化合物量をさらに計算することが可能な構成であってもよい。当該計算部33cの計算結果は、表示部34により表示される。   The calculation unit 33c calculates the gradient (dG / dT) of the temperature dependence of the conductivity of the test oil based on the measurement data from the conductivity measurement unit 31 and the temperature measurement unit 32 by the installed program. Can do. Moreover, the structure which can further calculate the acid value of a test oil, the amount of polymers, chromaticity, and the amount of polar compounds from dG / dT may be sufficient. The calculation result of the calculation unit 33c is displayed on the display unit 34.

一方、本発明にかかるフライ用器具は、上記本発明の評価装置を備えることを特徴としている。フライ用器具は、てんぷら、フライを行なうために用いられる器具であり、少なくとも食用油が注入され、揚げだねが投入されるフライ槽を有している。本発明にかかるフライ用器具は、上記フライ槽に本発明の評価装置を別途付加された構成であってもよいし、上記説示した本発明の評価装置の被験油固定部が、上記フライ槽そのものであるという構成であってもよい。また食用油をフライ可能な温度まで加熱することができる加熱部を備えた構成であってよい。なお上記の通り、本発明の評価装置における被験油固定部がフライ槽に相当する構成では、当該フライ槽に温度制御可能な加熱部が備えられており、当該加熱部によって食用油をフライ可能な温度に制御することができる。   On the other hand, the instrument for frying according to the present invention is characterized by including the evaluation device according to the present invention. The frying device is a device used for tempura and frying, and has a frying tank into which at least edible oil is injected and frying sauce is put. The instrument for frying according to the present invention may have a configuration in which the evaluation device of the present invention is separately added to the above-mentioned frying tank, or the test oil fixing part of the above-described evaluation device of the present invention is the above-mentioned frying tank itself. The structure of being may be sufficient. Moreover, the structure provided with the heating part which can heat cooking oil to the temperature which can be fried may be sufficient. In addition, as above-mentioned, in the structure by which the test oil fixing | fixed part in the evaluation apparatus of this invention corresponds to a frying tank, the said heating tank is equipped with the heating part which can control temperature, and cooking oil can be fried by the said heating part. Temperature can be controlled.

上記本発明の評価装置およびフライ用器具には、上記構成に限定されるものではなく、その他必要な構成を適宜含んでいてもよい。   The evaluation apparatus and the fly instrument of the present invention are not limited to the above-described configuration, and may include other necessary configurations as appropriate.

なお本発明は食用油のみに適用されるものではなく、潤滑油、燃料油等をも含む油、油脂に適用可能であることはいうまでもない。   Needless to say, the present invention is not only applicable to edible oils, but can also be applied to oils and fats including lubricating oils, fuel oils and the like.

本発明は上述した各実施形態に限定されるものではなく、請求項に示した範囲で種々の変更が可能であり、異なる実施形態にそれぞれ開示された技術的手段を適宜組み合わせて得られる実施形態についても本発明の技術的範囲に含まれる。   The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

本発明によれば、フライ食品の加工に用いられる食用油の劣化を簡便かつ正確に評価することができ、フライ食品の製造において食用油の交換時期を即座に判断することが可能となる。したがって、本発明はフライ食品の製造を行なう食品加工業、フライ食品を顧客に提供する外食産業等に利用が可能である。   ADVANTAGE OF THE INVENTION According to this invention, deterioration of the edible oil used for processing of fried food can be evaluated easily and correctly, and it becomes possible to determine immediately the replacement | exchange time of edible oil in manufacture of fried food. Therefore, the present invention can be used in a food processing industry for producing fried foods, a restaurant industry for providing fried foods to customers, and the like.

静電容量、導電率(コンダクタンス)、および抵抗の測定を行なうことができる誘電特性測定装置の概略図である。It is the schematic of the dielectric property measuring apparatus which can measure an electrostatic capacitance, electrical conductivity (conductance), and resistance. 図2(a)は静電容量、導電率(コンダクタンス)、および抵抗の測定を行なうことができる誘電特性測定装置に備えられた平行平板電極の斜視図であり、図2(b)は、同平行平板電極の上面図である。FIG. 2A is a perspective view of a parallel plate electrode provided in a dielectric property measuring apparatus capable of measuring capacitance, conductivity (conductance), and resistance, and FIG. It is a top view of a parallel plate electrode. 被験油(F2)の温度と誘電率との関係を示すグラフである。It is a graph which shows the relationship between the temperature of a test oil (F2), and a dielectric constant. 被験油(H1)の温度と誘電率との関係を示すグラフである。It is a graph which shows the relationship between the temperature of a test oil (H1), and a dielectric constant. 被験油(A2)の温度と誘電率との関係を示すグラフである。It is a graph which shows the relationship between the temperature of a test oil (A2), and a dielectric constant. 被験油(A3)の温度と誘電率との関係を示すグラフである。It is a graph which shows the relationship between the temperature of a test oil (A3), and a dielectric constant. 被験油(F2)の温度と導電率(コンダクタンス)との関係を示すグラフである。It is a graph which shows the relationship between the temperature of test oil (F2), and electrical conductivity (conductance). 被験油(H1)の温度と導電率(コンダクタンス)との関係を示すグラフである。It is a graph which shows the relationship between the temperature of test oil (H1), and electrical conductivity (conductance). 被験油(A2)の温度と導電率(コンダクタンス)との関係を示すグラフである。It is a graph which shows the relationship between the temperature of test oil (A2), and electrical conductivity (conductance). 被験油(A3)の温度と導電率(コンダクタンス)との関係を示すグラフである。It is a graph which shows the relationship between the temperature of test oil (A3), and electrical conductivity (conductance). 被験油(F2)の劣化程度と誘電率との関係を示すグラフであり、(a)は酸価と誘電率との関係を示し、(b)は重量物量と誘電率との関係を示し、(c)は色度と誘電率の関係を示す。It is a graph which shows the relationship between the deterioration degree of test oil (F2), and a dielectric constant, (a) shows the relationship between an acid value and a dielectric constant, (b) shows the relationship between a heavy load and a dielectric constant, (C) shows the relationship between chromaticity and dielectric constant. 被験油(H1)の劣化程度と誘電率との関係を示すグラフであり、(a)は酸価と誘電率との関係を示し、(b)は重量物量と誘電率との関係を示し、(c)は色度と誘電率の関係を示す。It is a graph showing the relationship between the degree of deterioration of the test oil (H1) and the dielectric constant, (a) shows the relationship between the acid value and the dielectric constant, (b) shows the relationship between the weight amount and the dielectric constant, (C) shows the relationship between chromaticity and dielectric constant. 被験油(A2)の劣化程度と誘電率との関係を示すグラフであり、(a)は酸価と誘電率との関係を示し、(b)は重量物量と誘電率との関係を示し、(c)は色度と誘電率の関係を示す。It is a graph showing the relationship between the degree of deterioration of the test oil (A2) and the dielectric constant, (a) shows the relationship between the acid value and the dielectric constant, (b) shows the relationship between the weight amount and the dielectric constant, (C) shows the relationship between chromaticity and dielectric constant. 被験油(A3)の劣化程度と誘電率との関係を示すグラフであり、(a)は酸価と誘電率との関係を示し、(b)は重量物量と誘電率との関係を示し、(c)は色度と誘電率の関係を示す。It is a graph showing the relationship between the degree of deterioration of the test oil (A3) and the dielectric constant, (a) shows the relationship between the acid value and the dielectric constant, (b) shows the relationship between the weight amount and the dielectric constant, (C) shows the relationship between chromaticity and dielectric constant. 被験油(F2)の劣化程度と導電率との関係を示すグラフであり、(a)は酸価と導電率との関係を示し、(b)は重量物量と導電率との関係を示し、(c)は色度と導電率の関係を示す。It is a graph which shows the relationship between the deterioration degree of test oil (F2), and electrical conductivity, (a) shows the relationship between an acid value and electrical conductivity, (b) shows the relationship between a heavy load and electrical conductivity, (C) shows the relationship between chromaticity and electrical conductivity. 被験油(H1)の劣化程度と導電率との関係を示すグラフであり、(a)は酸価と導電率との関係を示し、(b)は重量物量と導電率との関係を示し、(c)は色度と導電率の関係を示す。It is a graph which shows the relationship between the deterioration degree of a test oil (H1), and electrical conductivity, (a) shows the relationship between an acid value and electrical conductivity, (b) shows the relationship between a heavy load and electrical conductivity, (C) shows the relationship between chromaticity and electrical conductivity. 被験油(A2)の劣化程度と導電率との関係を示すグラフであり、(a)は酸価と導電率との関係を示し、(b)は重量物量と導電率との関係を示し、(c)は色度と導電率の関係を示す。It is a graph which shows the relationship between the deterioration degree of a test oil (A2), and electrical conductivity, (a) shows the relationship between an acid value and electrical conductivity, (b) shows the relationship between a heavy load and electrical conductivity, (C) shows the relationship between chromaticity and electrical conductivity. 被験油(A3)の劣化程度と導電率との関係を示すグラフであり、(a)は酸価と導電率との関係を示し、(b)は重量物量と導電率との関係を示し、(c)は色度と導電率の関係を示す。It is a graph showing the relationship between the degree of deterioration of the test oil (A3) and the conductivity, (a) shows the relationship between the acid value and the conductivity, (b) shows the relationship between the weight amount and the conductivity, (C) shows the relationship between chromaticity and electrical conductivity. 全ての被験油(F2、H1、A2、A3)における温度と導電率(コンダクタンス)との関係を示すグラフである。It is a graph which shows the relationship between the temperature in all the test oil (F2, H1, A2, A3) and electrical conductivity (conductance). 被験油(F2)の導電率(コンダクタンス)の温度依存性の傾き(dG/dT)と、同被験油(F2)の劣化程度(酸価、重合物量、色度)との関係を示すグラフであり、(a)は酸価とdG/dTとの関係を示し、(b)は重量物量とdG/dTとの関係を示し、(c)は色度とdG/dTの関係を示す。A graph showing the relationship between the temperature dependence gradient (dG / dT) of the conductivity (conductance) of the test oil (F2) and the degree of degradation (acid value, polymer amount, chromaticity) of the test oil (F2). Yes, (a) shows the relationship between the acid value and dG / dT, (b) shows the relationship between the weight and dG / dT, and (c) shows the relationship between chromaticity and dG / dT. 被験油(H1)の導電率(コンダクタンス)の温度依存性の傾き(dG/dT)と、同被験油(H1)の劣化程度(酸価、重合物量、色度)との関係を示すグラフであり、(a)は酸価とdG/dTとの関係を示し、(b)は重量物量とdG/dTとの関係を示し、(c)は色度とdG/dTの関係を示す。A graph showing the relationship between the temperature dependence gradient (dG / dT) of the conductivity (conductance) of the test oil (H1) and the degree of deterioration (acid value, polymer amount, chromaticity) of the test oil (H1). Yes, (a) shows the relationship between the acid value and dG / dT, (b) shows the relationship between the weight and dG / dT, and (c) shows the relationship between chromaticity and dG / dT. 被験油(A2)の導電率(コンダクタンス)の温度依存性の傾き(dG/dT)と、同被験油(A2)の劣化程度(酸価、重合物量、色度)との関係を示すグラフであり、(a)は酸価とdG/dTとの関係を示し、(b)は重量物量とdG/dTとの関係を示し、(c)は色度とdG/dTの関係を示す。It is a graph which shows the relationship between the inclination (dG / dT) of the temperature dependence of the electrical conductivity (conductance) of test oil (A2), and the deterioration degree (acid value, polymer amount, chromaticity) of the test oil (A2). Yes, (a) shows the relationship between the acid value and dG / dT, (b) shows the relationship between the weight and dG / dT, and (c) shows the relationship between chromaticity and dG / dT. 被験油(A3)の導電率(コンダクタンス)の温度依存性の傾き(dG/dT)と、同被験油(A3)の劣化程度(酸価、重合物量、色度)との関係を示すグラフであり、(a)は酸価とdG/dTとの関係を示し、(b)は重量物量とdG/dTとの関係を示し、(c)は色度とdG/dTの関係を示す。It is a graph which shows the relationship between the inclination (dG / dT) of the temperature dependence of the electrical conductivity (conductance) of test oil (A3), and the deterioration degree (acid value, polymer amount, chromaticity) of the test oil (A3). Yes, (a) shows the relationship between the acid value and dG / dT, (b) shows the relationship between the weight and dG / dT, and (c) shows the relationship between chromaticity and dG / dT. 全ての被験油(F2、H1、A2、A3)の導電率(コンダクタンス)の温度依存性の傾き(dG/dT)と、同被験油(F2、H1、A2、A3)の劣化程度(酸価、重合物量、色度)との関係を示すグラフであり、(a)は酸価とdG/dTとの関係を示し、(b)は重量物量とdG/dTとの関係を示し、(c)は色度とdG/dTの関係を示す。Temperature-dependent gradient (dG / dT) of conductivity (conductance) of all test oils (F2, H1, A2, A3) and the degree of deterioration (acid value) of the test oils (F2, H1, A2, A3) , Polymer amount, chromaticity), (a) shows the relationship between the acid value and dG / dT, (b) shows the relationship between the weight amount and dG / dT, (c ) Shows the relationship between chromaticity and dG / dT. 本発明にかかる食用油の劣化程度評価装置(一例)のブロック図である。It is a block diagram of the deterioration degree evaluation apparatus (an example) of the cooking oil concerning this invention.

符号の説明Explanation of symbols

30 評価装置
31 導電率測定部
32 温度測定部
33 制御部
33a 測定制御部
33b 温度制御部
33c 計算部
34 表示部
30 Evaluation Device 31 Conductivity Measurement Unit 32 Temperature Measurement Unit 33 Control Unit 33a Measurement Control Unit 33b Temperature Control Unit 33c Calculation Unit 34 Display Unit

Claims (7)

被験油の導電率の温度依存性の傾きを、当該被験油の劣化程度の指標として使用する工程を、含むことを特徴とする食用油の劣化程度の評価方法。   A method for evaluating the degree of deterioration of an edible oil, comprising the step of using the temperature-dependent slope of the conductivity of the test oil as an indicator of the degree of deterioration of the test oil. 上記被験油の導電率の温度依存性の傾きを、当該被験油の劣化程度の指標として使用する工程は、
被験油の導電率の温度依存性の傾きから、酸価、重量物量、色度および極性化合物量のうち少なくとも1つ以上を算出する工程であることを特徴とする請求項1に記載の評価方法。
The step of using the temperature-dependent slope of the conductivity of the test oil as an indicator of the degree of deterioration of the test oil,
2. The evaluation method according to claim 1, wherein the evaluation method is a step of calculating at least one of an acid value, a weight amount, a chromaticity, and a polar compound amount from a temperature-dependent gradient of the conductivity of the test oil. .
上記被験油の導電率の温度依存性の傾きを、当該被験油の劣化程度の指標として使用する工程は、
被験油の導電率の温度依存性の傾きが所定の値以上となった場合に、被験油が食用油として使用不可であると判断する工程であることを特徴とする請求項1に記載の評価方法。
The step of using the temperature-dependent slope of the conductivity of the test oil as an indicator of the degree of deterioration of the test oil,
The evaluation according to claim 1, wherein the test oil is a step of judging that the test oil cannot be used as an edible oil when the gradient of the temperature dependence of the conductivity of the test oil becomes a predetermined value or more. Method.
少なくとも異なる2点以上の温度における被験油の導電率を測定し、当該被験油の導電率の温度依存性の傾きを算出する工程を、さらに含むことを特徴とする請求項1ないし3のいずれか1項に記載の評価方法。   4. The method according to claim 1, further comprising a step of measuring the conductivity of the test oil at at least two different temperatures and calculating a temperature-dependent slope of the conductivity of the test oil. 2. The evaluation method according to item 1. 上記温度が、140℃以上200℃以下であることを特徴とする請求項4に記載の評価方法。   The said temperature is 140 degreeC or more and 200 degrees C or less, The evaluation method of Claim 4 characterized by the above-mentioned. 被験油の導電率を測定する導電率測定部、
被験油の温度を測定する温度測定部、および
被験油の導電率の温度依存性の傾きを計算する計算部を備えることを特徴とする食用油の劣化程度評価装置。
A conductivity measuring unit for measuring the conductivity of the test oil,
An apparatus for evaluating the degree of deterioration of edible oil, comprising: a temperature measurement unit that measures the temperature of the test oil; and a calculation unit that calculates a gradient of temperature dependence of the conductivity of the test oil.
請求項6に記載の食用油の劣化程度評価装置を備えることを特徴とするフライ用器具。   A frying device comprising the edible oil deterioration degree evaluation device according to claim 6.
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