WO1995029600A1

WO1995029600A1 - Method and apparatus for producing a liquid from fruit

Info

Publication number: WO1995029600A1
Application number: PCT/GB1995/000989
Authority: WO
Inventors: Charles Forsyth
Original assignee: Recordagent Limited
Priority date: 1994-04-29
Filing date: 1995-05-01
Publication date: 1995-11-09
Also published as: AU2316595A

Abstract

A method and apparatus for producing a liquid from fruit, and especially for producing a palatable water-based liquid, suitable for use as a beverage, which contains flavour elements of the fruit from which it is produced, and a liquid of the type produced by such method and/or apparatus. The method comprises extracting juice from vegetable matter and then extracting liquid from said juice by low temperature evaporation in partial vacuum of a substantial part of the water content of said juice and then condensation of the resultant steam or water vapour, so as to evaporate flavour elements of said vegetable matter and to condense at least some of said flavour elements. The liquid obtained comprises water which has been extracted from said vegetable matter and non-water material which has been extracted from said vegetable matter, the proportion of said non-water material being in the range 0.01 % (w/v) to 2.0 % (w/v), providing a palatable beverage. As an example, the liquid may be extracted from oranges and contain one or more of limonelle, citronellol, citral, L-carvone, D-limonene, and geraniol, nerol and linalool and their aldehydes. The apparatus comprises heating means for heating said vegetable matter; pressure reducing means for reducing the pressure in the vicinity of said vegetable matter to below atmospheric pressure in order to reduce the temperature required to evaporate a vapour from said vegetable matter; and condensing means for condensing said vapour to form said liquid. The apparatus may be a multiple stage multiple effect evaporator.

Description

METHOD AND APPARATUS FOR PRODUCING A LIQUID FROM FRUIT

The present invention relates to a method and apparatus for producing a liquid from fruit, and especially for producing a palatable water-based liquid, suitable for use as a beverage, which contains flavour elements of the fruit from which it is produced. The invention also relates to a liquid produced by the method and/or apparatus described herein.

It is well known to produce beverages from fruit and vegetables (both hereinafter referred to as fruit) and such beverages include fruit juices and squashes or cordials . Modern methods of producing fruit juices frequently include evaporation of a large proportion of the water content of juice removed from fruit. This facilitates storage and transport of the essential ingredients of the juice in concentrated form, before dilution with water is performed to provide a beverage with a concentration which approximates that of juice freshly extracted from the particular fruit.

Typically, the removal of the large proportion of the water content of the juice is performed by evaporation of the water from the juice, and such evaporation is typically effected by heating the juice by means of steam. Such heating may be performed at a pressure below atmospheric pressure in order to reduce the boiling point and thus avoid unduly impairing the flavour of the juice by excess heating.

It is known that, in addition to water, volatile flavour elements of the juice may be evaporated and therefore lost from the juice concentrate unless subsequently recovered and returned (see for example US Patent No. 2457315).

According to a first aspect of the present invention there is provided a method for producing a liquid from vegetable matter comprising extracting juice from said vegetable matter and then extracting said liquid from said juice.

Preferably, the step comprising extracting said liquid from said juice comprises evaporation of a substantial part of the water content of said juice and then condensation of the resultant steam or water vapour.

Preferably, said evaporation includes evaporation of flavour elements of said vegetable matter and said condensation includes condensation of at least some of said flavour elements.

Preferably, said evaporation comprises low temperature evaporation in a partial vacuum.

Preferably said evaporation comprises evaporation from vegetable matter at a temperature of not greater than 85°C. Successively more preferable is evaporation from vegetable matter at temperatures of not greater than 75°C, 65°C, 60°C and 55°C. Preferably, said step of evaporation comprises evaporation of water from vegetable matter with a solids content of not more than 30% (w/v) .

More preferably, said step of evaporation comprises evaporation of water from vegetable matter with a solids content of not more than 20% (w/v) .

Even more preferred is that said step of evaporation comprises evaporation of water from vegetable matter with a solids concentration of not more than 17% (w/v), and most preferably of not more than 16% (w/v) .

Said method may include the steps of at least one of carbonation, filtration, oxygenation or centrifugation of said liquid.

According to a second aspect of the present invention there is provided a liquid derived from vegetable matter said liquid comprising water which has been extracted from said vegetable matter and non-water material which has been extracted from said vegetable matter, the proportion of said non-water material being in the range 0.01% (w/v) to 2.0% (w/v).

Preferably, said liquid is palatable.

Preferably, said liquid contains substantially no matter that is not derived from said vegetable matter.

Preferably, said vegetable matter comprises oranges and said non-water material includes one or more of limonelle, citronellol, citral, L-carvone, D-limonene, and geraniol, nerol and linalool and their aldehydes.

Said liquid may be carbonated. According to a third aspect of the present invention there is provided apparatus for producing a liquid from vegetable matter comprising: heating means for heating said vegetable matter; pressure reducing means for reducing the pressure in the vicinity of said vegetable matter to below atmospheric pressure in order to reduce the temperature required to evaporate a vapour from said vegetable matter; and condensing means for condensing said vapour to form said liquid.

Preferably, said apparatus comprises a multiple stage multiple effect evaporator having selection means in order to allow the vapour from stages at which the vegetable matter has not more than a predetermined concentration of solids and is at a temperature not higher than a predetermined temperature, to be selected, without mixing with vapour from stages in which the juice has a concentration of solids higher than said predetermined concentration or a temperature above said predetermined temperature, and condensation means for condensing said selected vapour.

Preferably, said predetermined concentration of solids is in the range 16-30% (w/v) .

Preferably said predetermined temperature is not higher than 85°C, and still more preferably, not higher than 65°C.

Embodiments of the invention will now be described, by way of example with reference to the accompanying drawings in which:

Figure 1 is a schematic plan of apparatus suitable for performing the method and producing the product of the present invention. Figure 2 is a schematic diagram illustrating a prior art method of juice concentration which may be adapted for the purposes of the present invention, suitable for large scale commercial use.

With reference to Figure 1 a method and apparatus for producing a liquid from fruit will be described.

Figure 1 shows schematically an embodiment of apparatus for producing liquid according to- the present invention. The apparatus, generally designated 10 includes an inlet 11 for fruit juice, typically with a solids content of about 12% (w/v) and a heating pipe 12 for carrying the fruit juice through a steam jacket 13. The apparatus further comprises a separating chamber 14 having a first outlet pipe 15 adapted to carry concentrated juice away from the chamber 14, to a reservoir 16, and a second outlet pipe 17, adapted to carry matter evaporated from the juice away from the chamber 14, which leads to a condenser 18. The condenser 18 is provided with an outlet pipe 19 through which condensate may exit from the condenser 18 to a collecting chamber 20. The apparatus is sealable by first, second, third and fourth valves, 21, 22, 23, 24, enabling a partial vacuum to be applied to the apparatus.

In use juice enters the apparatus through the inlet 11, and passes through the heating pipe 12 where it is heated by means of steam applied to the steam jacket 13. The juice is heated sufficiently to enable boiling to take place, the temperature required being dependent upon the vacuum applied. The heated juice enters the separating chamber 14 from where evaporated matter, comprising mainly water, but also including volatile flavour elements from the juice, is drawn through the second outlet pipe 17 towards the condenser 18. The remainder of the juice leaves the separating chamber 14 via the first outlet pipe 15 from which it is fed to the reservoir 16 where it is stored before being recirculated through the apparatus. The evaporated matter is condensed by the condenser 18 and the resulting condensate is collected in the collecting chamber 20.

The end products made by the described apparatus are therefore concentrated juice which is a known commercial product, and a condensate comprising water and various derivative substances from the fruit juice.

By selecting the degree of partial vacuum applied to the apparatus the boiling point of the juice may be selected and this temperature, as well as the length of time for which the juice is maintained at this temperature, affects characteristics, including the taste, of both the concentrated juice and the condensate. It will become evident that the taste of the condensate is much more temperature sensitive than the taste of the concentrated juice.

Traditionally, in the production of concentrated juice the matter evaporated from the juice has been discarded, sometimes after extraction of some of the non-water elements which have a fruit flavour.

In this embodiment of the present invention, however, the liquid condensate is not discarded but is a useful end product. The product preferably consists of substantially the entire condensate including both water and fruit flavour elements. However, the fruit flavour elements may be removed in order to provide substantially pure water. In either case the condensate may be carbonated, may be oxygenated in order to eliminate the possibility of cloud formation, and/or may be filtered or centrifuged in order to remove organic material which may cause clouding. The condensate produced from vapour evaporated from juice at relatively low temperatures tastes surprisingly pleasant and is commercially useful as a saleable beverage, providing a valuable resource from what has traditionally been regarded and treated as a waste product.

However, in order to be saleable as a beverage the condensate must be palatable and it has become evident that merely condensing all the vapour removed from juice during the concentration process does not result in a pleasant tasting condensate.

In order to produce a palatable condensate the temperature at which the volatile material is removed from the juice must be controlled, and it has been found that the temperatures which produce acceptable condensates vary with the percentage of solid constituents of the juice at the time of removal of said volatile material.

Typically in the concentration of, for example, orange juice the solid content is increased from about 12% (w/v) to about 65% (w/v) . However, condensate produced from vapour removed from juice at the upper end of this range of solid concentrations is unpalatable, unless the removal took place at exceptionally low pressures, allowing correspondingly low temperatures to be employed. It would not, however, be commercially viable to operate at such low pressures.

In order to determine the palatability of condensates produced under various conditions three trials were performed. The trials each related to the concentration of orange juice and production of an associated condensate.

In the first trial (trial 1), juice was maintained at a pressure of 0.15 Bar (1.5 x 10 Pa) and temperature of 55°C.

In the second trial (trial 2), juice was maintained at a pressure of 0.25 Bar (2.5 x 10 Pa) and temperature of 65°C.

In the third trial (trial 3), juice was maintained at a pressure of 0.38 Bar (3.8 x 10 Pa) and temperature of 75°C.

Samples of condensate were collected at regular intervals and subjected to sensory evaluation.

At each pressure/temperature condition, condensate fractions were collected from orange juice having the following concentrations of solids.

Fraction 1 12.0% 13.4% (w/v) Fraction 2 13.5% 14.9% (w/v) Fraction 3 15.0% 16.9% (w/v) Fraction 4 17.0% 19.5% (w/v) Fraction 5 19.6% 22.9% (w/v) Fraction 6 23.0% 27.9% (w/v) Fraction 7 28.0% 35.5% (w/v) Fraction 8 35.6% 50.0% (w/v)

Each sample of condensate was evaluated by a small panel of experienced sensory evaluation specialists. Their consensus comments on each fraction of condensate are summarised in the following Table.

FRACTION SUMMARY COMMENTS

TRIAL 1 TRIAL 2 TRIAL 3

Fresh citrus Fresh, juicy, Fresh, juicy, flavour. bright, very citrus Some citrus pleasant. flavour. oil notes.

Slightly less Less intense Less flavour intense than than (1) . than (1) . (1) . Same Some quality, Some slight quality but lacking vegetable citrus depth. notes. flavour.

Less intense As above (2) . As above (2) and fresh. Not unpleasant.

Not as fresh, As above (3) As above (3) less intense, but not unpleasant.

Slightly Little citrus Little harsh notes. Some citrus. Some aftertaste, cooked notes. rubbery not flavour. unpleasant.

Not very Stronger Harsh, orange-like. cooked rubbery. Little flavour. flavour. Not unpleasant.

Pithy notes . Rubbery, As above. meaty.

Pithy notes As above. As Above. stronger. Not very pleasant.

During these trials, the juice was subjected to relatively long heating regimes of up to two hours. Industrially, the process is completed within ten minutes. Thus, in the trials the adverse effect on the taste of the condensate is likely to be greater than would occur if the condensate were produced on a commercial scale.

Analysis has shown that the condensates contained limonelle, citronellol, citral, L-carvone, D-limonene, and geraniol, nerol and linalool and their aldehydes. The condensates were however, substantially free of contaminant which often occur in natural mineral waters, such as nitrates and lead.

The subjective analysis shows that the taste of the condensate depends on the stage of the concentrate production process from which it was taken. Condensate from more concentrated juice did not have the pleasant, fresh orange taste of that taken from less concentrated juice. As the juice became more concentrated, and as it underwent more extensive heating, there were gradually generated "cooked" flavour notes. These cooked notes, which some taste panellists described as "meaty", "rubbery" and "musty" are undesirable.

Preparation of palatable condensate is therefore not simply a matter of collecting and condensing all the vapour produced during the commercial concentration of juice. Selectivity must be employed.

Condensate obtained from juice with a concentration of greater that 30% (w/v) solids may have associated off- tastes which makes it unpalatable. This is in contrast to the concentrated juice itself which is considered to maintain acceptable taste characteristics upon dilution despite having been concentrated to 65% (w/v) solids. It is evident that condensate collected from juice at 55°C (trial 1) remains palatable at a higher solids content of the juice than condensate collected from juice which is at 65°C (trial 2). Similarly, condensate collected from juice at 65°C remains palatable at a higher solids content of the juice than condensate collected from juice which is at 75°C (trial 3). Various combinations of temperature and solids content may be selected in order to provide the desired taste characteristics.

In order to produce a palatable condensate at commercially viable pressures the proportion of solids in the juice from which the vapour which formed the concentrate is removed should be limited to a maximum of about 30% (w/v) .

Volatile matter removed from the juice which has a solid concentration of 30-65% (w/v) may be treated in the traditional way, that is it may be treated in order to remove any valuable substance and the remaining water may be discarded. The range of concentration 12- 30% (w/v) is not unduly restrictive in practice since more condensate is formed in this range than in the remaining 30-65% (w/v) range.

The embodiment of apparatus described and illustrated in Fig. 1 is considerably less complex than the apparatus currently used for producing concentrated fruit juice commercially.

The great majority of installations for producing concentrated fruit juice commercially, are multiple stage, multiple effect evaporators. In such evaporators the juice to be concentrated, rather than being recirculated several times through a single heating and separating system as in the apparatus of Figure 1, passes through multiple stages, becoming more concentrated with each successive stage. The various stages operate at different pressures and temperatures. The juice is heated by steam (which is kept separate from the juice so that the steam and juice do not mix) .

Figure 2 is a schematic, illustrating the flow of juice and steam through a known multiple stage, multiple effect evaporator.

The illustrated evaporator has seven juice stages and seven steam effects. The flow of juice through the successive seven stages is illustrated, and the flow of steam through its successive seven effects is also shown.

As can be seen by from Figure 2 the first steam effect is at juice stage 3 which is when both steam and juice are at their highest temperature. The steam is then mixed with the vapour driven off the juice at stage 3, and the combination is used as the heating medium for the juice at stage 4 (having been used to preheat juice which has not yet reached stage 3). Subsequently, vapour evaporated from stage 4 is mixed into the heating medium and the mixture used as a heating medium for stage 5 and so forth.

This multiple effect system of using the vapour driven off the juice at each stage as part of the heating medium for the other stages (at subsequent effects) means that the steam initially fed into the system produces approximately the same amount of steam for each effect. Thus in a seven effect evaporator the introduced steam produces about seven times its own mass in evaporated vapours. This provides an exceptionally energy efficient method of concentrating, for example, fruit juice. A result of such a system is that the vapour driven off the juice at each of the stages is mixed with the vapour driven off the juice at each of the other stages by the time it leaves the installation.

This vapour from stages 1 and 2 is mixed with vapours from the stages of the steam's previous effects, that is stages 3, 4, 5 and 6. Thus the vapour from stages 1 and 2, which may operate at relatively low temperatures (up to about 75%) and relatively low solids concentrations (15-19% (w/v)) is mixed with the vapour from stages 3, 4, 5 and 6 which all operate at higher temperatures and higher concentrations.

Although the temperatures and solids concentrations in multiple stage, multiple effect evaporators may vary, it is generally true that vapour evaporated at the high temperature stages is combined with that evaporated at the lower temperature stages, thus rendering it impracticable to condense the vapour from the low temperature stages to form a palatable beverage.

Evidently, therefore, the potential of the vapour of stages 1 and 2 to be condensed to form a saleable palatable liquid has traditionally been destroyed by mixing with vapour carrying unacceptable flavours.

However, such a system could be adapted in accordance with the present invention so as to allow the vapour from stages 1 and 2 to be selected, collected and condensed, without mixing with the vapour from the other stages, in order to form a palatable and saleable beverage. This is in contrast to present practice in which the volatile products of each of the chambers are treated in the same way, or, at least, in which the water content of said volatile products are treated in the same way.

By selecting volatile matter produced from juice having an upper limit of percentage solids and an upper limit of temperature, where the upper limit of temperature decreases as the percentage of solids increases, a palatable fluid condensate may be economically produced.

Claims

1. A method for producing a liquid from vegetable matter comprising extracting juice from said vegetable matter and then extracting liquid from said juice.

2. A method as claimed in Claim 1, wherein the step comprising extracting liquid from said juice comprises evaporation of a substantial part of the water content of said juice and then condensation of the resultant steam or water vapour.

3. A method as claimed in Claim 2, wherein said evaporation includes evaporation of flavour elements of said vegetable matter and said condensation includes condensation of at least some of said flavour elements.

4. A method as claimed in Claim 3, wherein said evaporation comprises low temperature evaporation in a partial vacuum.

5. A method as claimed in Claim 4, wherein said evaporation comprises evaporation from vegetable matter at a temperature of not greater than 85°C.

6. A method as claimed in Claim 4, wherein said evaporation from vegetable matter is at a temperature not greater than 75°C.

7. A method as claimed in Claim 4, wherein said evaporation from vegetable matter is at a temperature not greater than 65°C.

8. A method as claimed in Claim 4, wherein said evaporation from vegetable matter is at a temperature not greater than 60°C.

9. A method as claimed in Claim 4, wherein said evaporation from vegetable matter is at a temperature not greater than 55°C.

10. A method as claimed in any one of Claims 2 to 9, wherein said step of evaporation comprises evaporation of water from vegetable matter with a solids content of not more than 30% (w/v) .

11. A method as claimed in any one of Claims 2 to 9, wherein said step of evaporation comprises evaporation of water from vegetable matter with a solids content of not more than 20% (w/v) .

12. A method as claimed in any one of Claims 2 to 9, wherein said step of evaporation comprises evaporation of water from vegetable matter with a solids concentration of not more than 17% (w/v) .

13. A method as claimed in any one of Claims 2 to 9, wherein said step of evaporation comprises evaporation of water from vegetable matter with a solids concentration of not more than 16% (w/v) .

14. A method as claimed in any preceding Claim, further including the steps of at least one of carbonation, filtration, oxygenation or centrifugation of said liquid.

15. A liquid derived from vegetable matter, said liquid comprising water which has been extracted from said vegetable matter and non-water material which has been extracted from said vegetable matter, the proportion of said non-water material being in the range 0.01% (w/v) to 2.0% (w/v).

16. A liquid as claimed in Claim 15, wherein said liquid is a palatable beverage.

17. A liquid as claimed in either one of Claims 15 or 16, wherein said liquid contains substantially no matter that is not derived from said vegetable matter.

18. A liquid as claimed in either one of Claims 16 or 17, wherein said vegetable matter comprises oranges and said non-water material includes at least one of liraonelle, citronellol, citral, L-carvone, D-limonene and geraniol, nerol and linalool and their aldehydes.

19. A liquid as claimed in any one of Claims 15 to 18, wherein said liquid is carbonated.

20. Apparatus for producing a liquid from vegetable matter comprising: heating means for heating said vegetable matter; pressure reducing means for reducing the pressure in the vicinity of said vegetable matter to below atmospheric pressure in order to reduce the temperature required to evaporate a vapour from said vegetable matter; and condensing means for condensing said vapour to form said liquid.

21. Apparatus as claimed in Claim 20, wherein said apparatus comprises a multiple stage multiple effect evaporator having selection means in order to allow the vapour from stages at which the vegetable matter has not more than a predetermined concentration of solids and is at a temperature not higher than a predetermined temperature, to be selected, without mixing with vapour from stages in which the juice has a concentration of solids higher than said predetermined concentration or a temperature above said predetermined temperature, and condensation means for condensing said selected vapour.

22. Apparatus as claimed in Claim 21, wherein said predetermined concentration of solids is in the range 16-30% (w/v).

23. Apparatus as claimed in either one of Claims 21 or 22, wherein said predetermined temperature is not higher than 85°C, and still more preferably, not higher than 65°C.