GB2321841A

GB2321841A - Separation of date kernels

Info

Publication number: GB2321841A
Application number: GB9802787A
Authority: GB
Inventors: John Karkalas; Robert Marshall
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-02-11
Filing date: 1998-02-11
Publication date: 1998-08-12
Anticipated expiration: 2018-02-11
Also published as: GB9802787D0; GB2321841B; EG20686A

Abstract

Date kernels are separated from dates by agitating dates with water. The water is preferably heated to 80-90 C and the separation may be carried out in a vessel equipped with a shaft carrying blades. The kernels are separated from the slurry of water and date pulp and are either roasted and ground for use as a coffee substitute or are pulverised to give a growth medium for micro-organisms. The slurry is separated into a fibrous residue that is dried to give dietary fibre and a saccharine extract that is concentrated to give a syrup.

Description

DATE PROCESSING METHOD AND APPARATUS This invention relates to a date processing method and apparatus.

Dates are a staple crop in countries such as Iran, Egypt, Iraq, Saudi Arabia and Pakistan. Annual production exceeds 3 million tonnes, and a large percentage of this fruit is dried naturally for future use. Dried dates are self-preserving due to their high sugar content/low water activity.

Whole dates consist approximately of 85% edible fruit tissue and 15% kernels. Composition of the edible portion is approximately 70% sugars, 8% dietary fibre, 2.5% protein, 1.5% mineral matter and 18% water.

Date kernels are generally considered to be waste, and processing of dates normally requires that they have first been prepared by removal of their kernels.

According to a first aspect of the present invention there is provided a process for the utilization of dates comprising separating date kernels from dates.

Preferably, the extraction of kernels from the dates is by means of supplying a quantity of heated water to the dates.

Preferably, the imbibition of heated water softens the date tissue.

Preferably, there is concomitant agitation of the dates.

Preferably, hydrated date tissue is detached from the kernels and separated therefrom.

Preferably, the initial products of the process include date kernels and a slurry comprising water and hydrated date pulp.

Preferably, the slurry is separated into a fibrous residue and a saccharine extract. Said separation may be by filtration. Alternatively the residue and the extract may be separated centrifugally.

Preferably, the viscosity of the extract is determined by enzymic treatment. Enzymic treatment may be effected prior to separation to facilitate filtration.

Additionally or alternatively enzymic treatment may be effected subsequent to separation.

Preferably, said enzymic treatment comprises the depolymerisation of pectins and non-cellulosic polysaccharides.

Preferably, the extract is concentrated by means of a evaporator to produce a syrup. Consistency of the syrup may be controlled by the addition of edible polysaccharides.

Preferably, the residue is dried.

The kernels may be dried for storage for further processing. Further processing may include roasting or pulverizing. Alternatively, undried kernels may be pulverized.

According to a second aspect of the present invention there is provided an apparatus for processing dates, said apparatus including an extractor which separates date kernels from dates.

Preferably, the apparatus includes means to separate a slurry comprising water and hydrated date pulp into a liquid saccharine extract and insoluble fibrous residue.

Preferably, there is provided a filter means for the slurry. Alternatively, centrifugal separation means is provided for the slurry.

Preferably, the apparatus further includes treatment means for the date kernels, the saccharine extract and the fibrous residue.

Date kernel treatment means may comprise a drier.

Additionally or alternatively said date kernel treatment means may comprise means to pulverize wet or dry date kernels. The apparatus may also include means to treat pulverized kernels.

An evaporator is preferably provided for condensing the saccharine extract to a syrup. Preferably, the evaporator is a falling film evaporator.

Preferably, means is provided for adjustment of the consistency of the resultant syrup.

Preferably, a drier is provided to dry the fibrous residue.

According to a third aspect of the present invention there is provided an apparatus for the removal of kernels from dates comprising a partially perforated vessel to which heated water is supplied, and blade means to agitate the dates within the vessel.

Said blade means may be mounted on an axial shaft.

Preferably, said apparatus includes means to maintain the temperature of the water within the range 80-90 C.

Preferably, said apparatus produces date kernels and a slurry comprising water and hydrated date pulp.

According to a fourth aspect of the present invention there is provided a product comprising dried date kernels, wherein the date kernels are obtained from dates by supplying water and motion thereto.

Said dried date kernels may be roasted to provide a flavouring substance. Most preferably, the roasted dried date kernels are ground for use as a substitute for coffee.

According to a fifth aspect of the present invention there is provided a product comprising pulverized wet or dry date kernels, wherein the date kernels are obtained from dates by supplying water and motion thereto.

Said wet kernels may be pulverized to facilitate the growth of micro-organisms. These micro-organisms are preferably edible fungi.

According to a sixth aspect of the present invention there is provided a product comprising date syrup, wherein the date syrup is produced by condensing saccharine extract obtained from dates.

Preferably, consistency of the date syrup may be controlled by addition of edible polysaccharides.

According to a seventh aspect of the present invention there is provided a product comprising dried date residue.

Preferably, the dried date residue is used as dietary fibre.

Embodiments of the present invention will now be described as means of example only with reference to the accompanying tables and figures in which: Figure 1 is a pie chart showing the annual global production of dates; Figure 2 is a simplified schematic process diagram of the process and apparatus of the present invention; Figure 3 is a schematic flow diagram of the process and apparatus of the present invention; Figure 4 is a simple flow diagram demonstrating the utility of all products of the process of the present invention and approximate quantities of raw materials and products; Figure 5 is a flow diagram demonstrating possible uses of the products of the present invention; Figure 6 is a schematic elevation of an apparatus for the extraction of kernels from dates in accordance with the third aspect of the present invention; Figure 7 is a cross-section of Figure 6; and Table 1 gives an analysis of the composition of products in accordance with the fourth, fifth and sixth aspects of the present invention which are the products of the process and apparatus in accordance with the present invention.

Referring to Figures 2, 6 and 7, harvested whole dates are first introduced to an inspection/sorting table 4 from which suitable dates 2 are conveyed to a bucket elevator 6. The bucket elevator 6 delivers these whole dates 2 to a continuous extractor/destoner 8. The throughput of the extractor/destoner 8 is approximately two tonnes of dates per hour.

This extractor 8 is substantially cylindrical with a diameter of approximately two metres. The holdup of the lower portion of the extractor 8 is approximately 6 cubic metres. The extractor 8 comprises a horizontal vessel 10 with an axially fitted shaft 12. The shaft 12 supports arms 14 which are spirally disposed. At the end of said arms 14 are disposed blades 16. These blades 16 are constructed of rubber, PTFE or similar flexible materials.

Whole dates 2 are introduced at the first end of the vessel 10 and urged across the vessel 10 by the blades 16 on rotation of the shaft 12. Rotation of the shaft 12 is effected by a variable speed motor 13.

The base 18 of the vessel 10 is of metal sheet and of semicircular cross-section. Perforations 20 are disposed therein. These perforations 20 are of size smaller than an average date kernel.

Hot water 22 at 80-900C is provided to the contents of the vessel. The vessel 10 maintains this temperature for the water by means of heating elements 23 in an outer semi-circular jacket 24. The hot water 22 is fed to a level 21 in the vessel 10 at the same time as the dates 2 are introduced.

Imbibition of the water 22 by the dates occurs. This imbibition softens the flesh of the dates. Agitation of the dates causes the flesh to be detached from the kernels and form a slurry 25 with the water. This slurry 25 comprises 20-40% of total solids, and its concentration and density is 20-30 Brix. The slurry 25 is then forced through perforations 20 in the base 18 of the vessel 10 to an outer semicircular jacket 24.

A pump 26 is provided which discharges this slurry 25 from the jacket 24 to an enzyme treatment tank 32. The average time taken for this stage of the process is between 60-90 minutes.

En route to the enzyme treatment tank 32, the slurry 25 is passed through a heat exchanger 28 which cools the slurry 25 to a temperature of between 35-500C.

In the tank 32 lytic enzymes 34, which may be polysaccharide hydrolases, are added to the slurry.

These lytic enzymes 34 act on the slurry to depolymerize pectins and non-cellulosic polysaccharides therein. The lytic enzymes 34 have minimal effect on the cellulose constituent of the slurry.

This depolymerization leads to a reduction in the viscosity of the slurry. Reducing the viscosity of the slurry enables its more rapid and efficient filtration at a later stage of the process. Such depolymerization will ultimately produce as a final product of the process a syrup of low viscosity which will not set to a gel.

Addition of controlled quantities of enzymes to the slurry at various temperatures for varying periods of time will produce a syrup of any desired viscosity as a final product The treated slurry 33 is then removed and pumped by a pump 35 to a holding tank 38. En route to the holding tank 38, the treated slurry is heated to a temperature of between 70-850C by its passage across a heat exchanger 36.

The holding tank 38 provides a steady stream of slurry to a filter press 42. The slurry is pumped by means of pump 40 to the filter press 42.

The purpose of the filter press 42 is to separate the insoluble fibrous residue from the liquid saccharine extract which constitute the slurry. Although a filter press 42 is shown in this diagram, a belt filter or any other suitable design of filter may be used.

Alternatively the slurry is centrifuged through a continuous de-sludging centrifugal separator.

A receiving tank 44 for the filtrate 43, namely the liquid saccharine extract, is provided. At this stage of the process, the concentration and density of the extract is 20-30 Brix.

Further treatment of the extract can be effected at this stage by means of introduction of enzymes 46 to the filtrate tank 44. The purpose of such enzyme treatment is to digest colloidal matter. If left undigested, such colloidal matter imparts turbidity to the final product. Thus, digestion of such colloidal material is an additional or alternative method of controlling the ultimate viscosity of the syrup which is a final product of this process.

From the filtrate tank 44 the saccharine extract is supplied to an evaporator system 48. The evaporator system 48 concentrates the extract under reduced pressure. The evaporator system 48 is a falling film evaporator system of conventional type. Other types of evaporator system may be used. The evaporator may be ~ of single or of multiple effect.

The evaporator system 48 is of capacity sufficient to prevent loss of syrup through entrainment. A vacuum pump 50 is provided in the evaporator system 48 to reduce pressure.

Condensate 49 is extracted from the evaporator system 48 under pressure. A syrup pump 52 is provided for the extraction of the liquid product of the evaporator system 48. This liquid product is date syrup 53. A closed tank 54 is provided where date syrup 53 of concentration and density bf 65-85 Brix is collected.

The consistency of the syrup finally produced may be altered by the addition of appropriate edible polysaccharides. Suitable additives may include xanthan gum, pectins, gellan gum, guar gum, locust bean gum, carrageenin, alginates, alginate derivatives and carboxymethyl cellulose or mixtures thereof. In this way, the product produced may be tailored to requirements.

After filtration in the filter press 42, the solid component 41 of the slurry, namely the fibrous residue, is gathered into a hop 56 then conveyed to a drier. A drum drier 58 is illustrated, but a roller drier is equally of use. Alternatively any conventional method my be used to dry the residue.

Drying the residue produces dried date fibre 59.

Dried date fibre is a unique and valuable source of non-cereal dietary fibre. This fibre is produced in the form of flakes, and may be supplied in this form or ground to a powder to meet the ever increasing demand - therefor. This product comprises on average 50% dietary fibre, in a range from 35-55%.

The wet date kernels 60, retained in the extraction tank 8 after removal of the slurry, are lifted up by scoops 62 and progressively discharged down a chute 64 which leads to a washing conveyer 66. These kernels 60 can be processed in a variety of ways.

The wet kernels may be removed to conventional drying apparatus incorporated in this process, where they are dried and then stored until required. Further processing apparatus for dried date kernels includes means for roasting the dried date kernels 61 or a disintegrator 63. Roasting the kernels produces a product which has characteristic aroma and flavour of coffee with the additional advantage of being entirely free of caffeine. The roasted dried date kernels may be ground to the required size and used in place of coffee for example as a drink or for flavouring.

Alternatively the dry kernels may be pulverized in a disintegrator 63.

Alternatively wet kernels (which may first be stored in the dry state if required) may be removed to conventional pulverizing apparatus 63 incorporated in this process, and pulverized to a material with consistency of coarse meal. This material, when treated with the appropriate substances, produces a medium which facilitates the growth of fungal mycelia and supports the growth of edible mushrooms. It is possible to tailor the medium to particular applications.

In the process of the present invention dates are sorted and supplied with hot water, the temperature is maintained and the mixture is agitated in order to extract date kernels from the dates.

Once the date kernels have been separated from the dates, the resultant slurry is treated with enzymes to reduce its viscosity and is subsequently filtered to separate the insoluble fibrous residue from the liquid extract.

The date kernels are a product according to the fourth aspect of the present invention.

The extract is concentrated by evaporation under reduced pressure to produce a syrup in accordance with the fifth aspect of the present invention.

The fibrous residue is dried to produce a dried residue in accordance with the sixth aspect of the present invention.

Improvements and modifications can be made to the process, apparatus and products without departing from the scope of this invention.

Claims

1. A process for the utilization of dates comprising separating date kernels from date by agitating the dates and applying a quantity of heated water thereto.

2. A process as claimed in Claim 1 wherein hydrated date tissue is detached from the kernels and separated therefrom.

3. A process as claimed in Claim 2 wherein the initial products of the process include date kernels and a slurry comprising water and hydrated date pulp.

4. A process as claimed in Claim 3 which further comprises enzymic treatment of the slurry.

5. A process as claimed in Claim 3 or Claim 4 which further comprises the separation of the slurry into a fibrous residue and a saccharine extract.

6. A process as claimed in Claim 5 wherein separation of the slurry is by means of filtration.

7. A process as claimed in Claim 5 wherein separation of the slurry is by means of centrifugation.

8. A process as claimed in Claim 6 or Claim 7 which further comprises enzymic treatment of the extract.

9. A process as claimed in Claim 3 or Claim 8 wherein the enzymic treatment comprises the depolymerisation of pectins and non-cellulosic polysaccharides.

10. A process as claimed in Claims 5 to 9 which further comprises the concentration of the extract by an evaporator to produce a syrup.

11. A process as claimed in Claim 10 which further comprises the addition of edible polysaccharides to control the consistency of the syrup.

12. A process as claimed in Claims 5 to 11 which further comprises the step of drying the residue.

13. A process as claimed in Claim 12 which further comprises the step of roasting or pulverizing the dried residue.

14. A process as claimed in Claims 5 to 11 which further comprises the step of pulverizing the undried residue.

15. An apparatus for processing dates including an extractor which separates date kernels from dates.

16. An apparatus as claimed in Claim 15 including treatment means for the date kernels.

17. An apparatus as claimed in Claim 16 wherein the date kernel treatment means comprises a drier.

18. An apparatus as claimed in Claim 16 wherein the date kernel treatment means comprises means to pulverize wet or dry date kernels.

19. An apparatus as claimed in Claim 18 including means to treat pulverized date kernels.

20. An apparatus as claimed in Claims 15 to 19 including means to separate a slurry comprising water and hydrated date pulp into a liquid saccharine extract and insoluble fibrous residue.

21. An apparatus as claimed in Claim 20 wherein said means to separate a slurry comprises filter means.

22. An apparatus as claimed in Claim 20 wherein said means to separate a slurry' comprises centrifugal separation means.

23. An apparatus as claimed in Claims 20 to 22 including treatment means for the saccharine extract.

24. An apparatus as claimed in Claim 23 wherein the saccharine extract treatment means comprises an evaporator.

25. An apparatus as claimed in Claim 24 including means for adjustment of the consistency of the resultant syrup.

26. An apparatus as claimed in Claims 20 to 22 including treatment means for the fibrous residue.

27. An apparatus as claimed in Claim 26 wherein the fibrous residue treatment means comprises a drier.

28. An apparatus for the removal of kernels from dates comprising a partially perforated vessel to which heated water is supplied, and blade means to agitate the dates within the vessel.

29. An apparatus as claimed in Claim 28 wherein said blade means is mounted on an axial shaft.

30. An apparatus as claimed in Claim 28 or 29 including means to maintain the temperature of the water within the range 80-90 C.

31. An apparatus as claimed in Claims 28 to 30 which produces date kernels and a slurry comprising water and hydrated date pulp.

32. A product comprising dried date kernels, wherein the date kernels are obtained from dates by supplying water and motion thereto.

33. A product as claimed in Claim 32 roasted to provide a flavouring substance.

34. A product as claimed in Claim 33 ground for use as a substitute for coffee.

35. A product comprising pulverized wet or dry date kernels, wherein the date kernels are obtained from dates by supplying water and motion thereto.

36. A product to facilitate the growth of microorganisms comprising pulverized wet date kernels.

37. A product comprising date syrup produced by condensing saccharine extract obtained from dates.

38. A product as claimed in Claim 37 the consistency of which is determined by addition of edible polysaccharides.

39. A product comprising dried date residue for use as dietary fibre.

40. Process, apparatus and products substantially as hereinbefore described with reference to and as shown in the accompanying drawings.