AU664781B2 - Method of producing carrot juice - Google Patents

Description

66

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION NAME OF APPLICANT(S): Kagome Kabushiki Kalsha ADDRESS FOR SERVICE: DAVIES COLLISON CAVE Patent Attorneys 1 Little Collins Street, Melbourne, 3000.

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0 INVENTION TITLE: Method of producing carrot juice The following statement is a full description of this invention, including the best method of performing it known to me/us:- I Background of the Invention This invention relates to a method of producing carrot juice.

People drink many kinds of vegetable and fruit juice. For the production of such juice, not only is it necessary that the yield be good but the produced juice must retain the original color and flavor of the vegetable and/or fruit. This invention is in response to such requirement specifically for the production of carrot juice.

According to conventional methods of producing carrot juice, 1 0 carrots are heated in boiling water for inactivation of enzymes (blanching) and then crushed or grated to squeeze out the juice. For squeezing out the juice in such a process, S machines such as a pulper, a screw press, a guinard and a decanter are used either singly or in combination. One of the 15 problems with these conventional production methods is that e0 S o.

the juice cannot be squeezed out efficiently because of the structure of the machine for the purpose. Another problem is that the color and flavor elements of original carrots are not extracted efficiently and hence the squeezed liquid is not colored well. Still another problem is that the squeezed liquid acquires an off flavor because it takes a long time for the blanching and its flavor is also adversely affected. In summary, carrot juice of high quality cannot be produced with a high yield by a conventional production method.

In view of the above, U.S. Patent 3,787,589 has disclosed a method of heating carrots in a boiling aqueous solution of an edible acid for inactivation of enzyme, thereafter crushing or grating and using a filter press or the like to squeeze out the juice. Although the juice can be squeezed more efficiently by this method, the improvement is not sufficiently significant. Although the juice obtained by this method contains more color and flavor elements of carrots, the color of the juice is still poor. Although the time required for the blanching has been shortened, the juice retains an off flavor and its flavor is poor because the inactivation of 15 enzymes is still by blanching.

It is therefore an object of the invention to eliminate such problems of conventional methods of producing carrot juice and, in particular, to improve the flavor of the carrot juice by eliminating off flavor from the liquid squeezed from carrots.

Summary of the Invention As a result of diligent studies in view of the problems of conventional methods as described above, the present inveitors I I -3discovered an improved method of producing carrot juice, according to which carrots are sprayed, while they are being crushed or chopped, with an aqueous solution of citric acid or lemon juice with a specified amount of citric acid, and juice is squeezed out from these crushed or chopped carrots by means of a counter-rotation twin-screw extruder after they are heated for inactivation of enzymes.

Detailed Description of the Invention This invention relates to a method of producing carrot juice comprising the steps of: crushing or chopping carrots while spraying said carrots with an aqueous solution of citric acid or lemon juice such that the sprayed amount of citric acid from said aqueous solution or lemon juice is 0.05-0.5 weight of said carrots being crushed or chopped; effecting inactivation of enzyme by heating said crushed or chopped carrots; and squeezing said heated carrots to collect juice by means :g 20 of a counter-rotation twin-screw extruder.

Carrots to be used in the invention are preliminarily washed and sorted. If necessary, preliminarily peeled carrots may be used. For crushing or chopping such carrots, use may be made of a hammer mill, a crusher, a cutter or the like. It is preferable to crush or chop the carrots into pieces with average size of 3-20mm, and more preferably 5-10mm. If the average size becomes less than 3mm, the efficiency of

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950921,p:\opidab,5180P. pe,3 obtaining juice therefrom tends to become lower when they are squeezed by means of a counter-rotation twin-screw extruder, as will be described below. If the average size of these pieces is greater than 20mm, on the other hand, it becomes more troublesome to transport the pieces from one place to another. In the above, the so-called average size is determined by collecting 50 of the crushed or chopped pieces at random, determining the size of each piece by placing it on a horizontal plane such that its longest dimension lies horizontally, selecting eight evenly separated points around its circumference as seen vertically downward from above, measuring the lengths of the four line segments connecting (or the horizontal distances between) pairs of mutually opposite ones of these points, say, by using 15 calipers from above, and calculating the average of these four measured lengths and defining it to be the size of this piece, and calculating the average of the sizes of these 50 collected pieces.

While carrots are being crushed or chopped, they are sprayed 20 with an aqueous solution of citric acid or lemon juice such that the amount of citric acid therein which is sprayed is 0.05-0.5 weight and more preferably 0.1-0.2 weight of the crushed or chopped carrots. This is for the purpose of inhibiting enzymic reactions. Lemon juice to be used may be obtained by squeezing fresh lemons. Use may as well made of a -4condensed liquid obtained therefrom, or an aqueous solution of such a condel4sed liquid. If the sprayed amount of citric acid is less than 0.05 weight enzyrAic reactions cannot be inhibited adequately. If the citric acid content exceeds weight on the other hand, enzymic reactions can be inhibited but the carrot juice which is finally obtained becomes too strongly acid. Although the use of organic acids such as lactic acid and acetic acid may be considered for the pu;:pose of inhibiting enzymic reactions, these organic acids are not in harmony with the unique flavor of carrot juic' It is also effective to use salt water for spraying for the same purpose of using citric acid. For increasing the amount of color elements, or pigments (such as carotinoid), which can be extracted from carrots, a spray of ethyl alcohol is 15 effective. When salt water is sprayed, it is done with the spray of an aqueous solution of citric acid or lemon juice such that the salt content of the salt water is 0.1-1.0 weight and more preferably 0.3-0.7 weight of the crushed or chopped carrots. When ethyl alcohol is sprayed, it is done with the spray of an aqueous solution of citric acid or lemon e juice such that the content of ethyl alcohol is 0.5-3 weight and more preferably 0.7-1.5 weight of the crushed or chopped carrots. Both salt water and ethyl alcohol may be sprayed simultaneously with the spray of the aqueous solution of citric acid or lemon juice. The ranges of the rates at which salt water and/or ethyl alcohol may be used, are determined not only in view of how they can serve their purposes but also how they affect the unique flavor and color of carrot juice.

The crushed or chopped carrot pieces thus obtained are heated for inactivation of enzymes. For this heating process, it is preferable to use a sealed system such as a contherm because qualities unique to carrots can be retained and unwanted off flavor can be kept away by heating quickly inside a sealed system. The heating is usually carried out such that the temperature of the carrot pieces reaches 80-900C, and more particularly •After this process for inactivation of enzymes, the heated carrot pieces are squeezed by a counter-rotation twin-screw extruder to produce juice. The counter-rotation twin-screw extruder to be used according to the present invention may be S: characterized as having two mutually parallel shafts adapted.

to rotate in mut~ 7y opposite directions. Each shaft is provided with sced aich that the screws on the two shafts engage each other. These screws are surrounded by a barrel having slits or a screen net such that crushed or chopped carrot pieces thrown into this barrel are transported by the mutually engaging counter-rotation twin screws from an inlet end to an outlet end. In the meantime, the pieces are -6-

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squeezed and the juice thus obtained are collected through the slit or the screen net.

Co-rotation twin-screw extruders are being used for extracting vegetable oil from oil-producing seeds (as disclosed, for example, in U.S. Patent 3,450,034), but the rate of obtaining juice becomes lower in the case of carrot juice if a corotation twin-screw extruder is used.

When a counter-rotation twin-screw extruder is used according to the present invention, a plurality of screws, etc. are usually mounted continuously on each of the two counterrotation twin screws. Examples of screws which may be thus mounted include parallel screws, tapered screws, reverse screws and tapered collars. The combination of such screws also affects the rate of collecting juice and the quality of the juice which is squeezed. They may be combined from the i.eo inlet end to the outlet end in the order of parallel screw parallel screw tapered collar parallel screw tapered screw tapered screw tapered collar. A preferable 20 combination is in the order of parallel screw parallel screw tapered collar parallel screw tapered screw reverse screw tapered collar such that a reverse screw is included between the center and the outlet end. The reverse screw serves to apply pressure on the carrot pieces in the direction opposite to the direction of their transportation and this -7tends to improve the rate of juice collection and the quality of squeezed juice.

In order to improve the rate of juice collection by the squeezing process, it is preferable to cause a heating medium such as steam to flow through a hollow portion created in the barrel and/or the screws so as to heat the carrot pieces as they are being squeezed for juice collection. In order to improve the quality of the squeezed juice, furthermore, it is preferable to collect the juice in a nitrogen atmosphere.

Carrot juice with superior color and flavor can be obtained if the counter-rotation twin-screw extruder is placed inside an e e enclosure, the interior of the enclosure being filled with nitrogen and a nitrogen gas being supplied through the inlet *e for the crushed or chopped carrots.

15 In order to further explain the present invention and its effects more clearly, test examples and comparison examples will be described below, but it goes without saying that the invention is not limited by these test examples.

Part 1 (Production of carrot juice) Test Example 1 Commercially available carrots were peeled and washed with water. They were crushed into small pieces (of average size less than 2.0mm) by a crusher while they were sprayed with an -p_ aqueous solution of citric acid (with citric acid content of 10.0 weight such that citric acid would be 0.15 weight of the crushed carrots. Next, the crushed carrots thus obtained were supplied to a contherm (Model KV-12 produced by Iwai Kikai Kogyo-sha) and heated to 85 0 C for inactivation of enzymes. They were then squeezed by a counter-rotation twinscrew extruder to collect juice and the juice was cooled. The slit in the barrel of the extruder was 0.5mm in width and the screws were rotated at the rate of 10rpm. In the extruder, the screws were arranged according to the Screw Pattern A given below: Screw Pattern A: (Inlet side) parallel screw with length 150mm and groove depth of 15mm parallel screw with length 100mm and groove depth 3Cmm 15 tapered collar parallel screw with length 60mm and

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groove depth 6mm tapered screw with length and groove depth mm tapered scre w with length and groove depth 5mm tapered screw with length 40mm and groove depth 4mm tapered collar (outlet side).

20 Test Example 2

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Commercially available carrots, the same as used in Test Example 1, were peeled and washed with water. They were crushed into small pieces of average size 8.5mm by a crusher while they were sprayed with an aqueous solution of citric acid (with citric acid content of 5.0 weight such that -9citric acid would be 0.15 weight of the crushed carrots.

Inactivation of enzymes was carried out thereafter as in Test Example 1, and juice was squeezed by a counter-rotation twinscrew extruder and cooled.

Test Example 3 Commercially available carrots, the same as used in Test Example 1, were peeled and washed with water. They were chopped into small pieces of average size 12.7mm by a cutter while they were sprayed with an aqueous solution of citric acid (with citric acid content of 5.0 weight salt water (with salt content of 10.0 weight and ethyl alcohol such that the sprayed amount of citric acid, salt and ethyl alcohol would be respectively 0.15 weight 0.3 weight and 0.8 weight of the crushed carrots. Inactivation of enzymes was carried out thereafter as in Test Example 1, and juice was squeezed by a counter-rotation twin-screw extruder and cooled.

*s Test Example 4 Commercially availabJe carrots, the same as used in Test *eeo Example 1, were peeled and washed with water. They were crushed into small pieces of average size 9.5mm by a crusher while they were sprayed with a 10-times diluted aqueous solution obtained from commercially available condensed lemon juice (condensed 6 times, citric acid content of 36.0 weight such that the sprayed amount of citric acid would be 0.15 weight of the crushed carrots. Inactivation of enzymes was carried out thereafter as in Test Example 1, and juice was squeezed by a counter-rotation twin-screw extruder and cooled.

In this process, the extruder was placed inside an enclosure, the interior of which was filled with nitrogen, and nitrogen was supplied into the extruder through its inlet for crushed carrots.

Test Example Commercially available carrots, the same as used in Test Example 1, were peeled and washed with water. They were crushed into small pieces of average size 9.5mm by a crusher while they were sprayed with a 5-times diluted aqueous solution obtained from the same commercially available condens3ed lemon juice (as used in Test Example 4) such that the sprayed amount of citric acid would be 0.15 weight of the crushed carrots. Inactivation of enzymes was carried out S- thereafter by using the contherm (as in Test Example 1) and heating the crushed carrots to 850C. Juice was squeezed by a counter-rotation twin-screw extruder and cooled. The slit in '.20 the barrel of the extruder was 0.5mm in width and the screws were rotated at the rate of 10rpm. In the extruder, the screws were arranged according to the Screw Pattern B given below: Screw Pattern B: (Inlet side) parallel screw with length 150mm and groove depth of 15mm parallel -11screw with length 100mm and groove depth 10mm tapered collar parallel screw with length 60mm and groove depth 6mm tapered screw with length and groove depth 5mm reverse screw with length 40mm and groove depth 4mm tapered collar (outlet side).

Test Example 6 Commercially available carrott. the same as used in Test Example 1, were peeled and washed with water. They were .crushed into small pieces of average size 9.5mm by a crusher while they were sprayed with a 5-times diluted aqueous solution obtained from the same commercially available condensed lemon juice (as used in Test Example salt water (with salt content of 10.0 weight and ethyl alcohol such that the sprayed amounts of citric acid, salt and ethyl alcohol would be respectively 0.15 weight 0.3 weight and 0.8 weight of the crushed carrots. Inactivation of enzymes was carried out thereafter as in Test Example 5, and juice was *e squeezed by a counter-rotation twin-screw extruder and cooled.

20 The juice was squeezed in a nitrogen atmosphere as done in Test Example 4.

Comparison Example 1 Commercially available carrots, the same as used in Test Example 1, were washed with an alkali and then with water.

-12i They were subjected to a blanching process for inactivation of enzymes inside hot water of 90-95oC, cooled and peeled. They were crushed and grated by a hammer mill and squeezed by a decanter to collect juice.

Comparison Example 2 It was the same as Comparison Example 1 except use was made of a co-rotation twin-screw extruder (as described in U.S. Patent 3,450,034) instead of a counter-rotation twin-screw extruder.

Comparison Example 3 s .a -Commercially available carrots, the same as used in Test Example 1, were peeled and washed with water. They were soaked in boiling aqueous solution of citric acid with content of 5 wight (0.078N) for 5 minutes (for blanching), and they were squeezed to collect juice after being crushed by a filter press.

S Comparison Example 4 Commercially available carrots, the same as used in Test Example 1, were peeled and washed with water. They were crushed into small pieces of average size 9.5mm by a crusher while they were sprayed with a 10-times diluted aqueous solution obtained from commercially available condensed lemon juice (the same as used in Test Example 4) such that the sprayed amount of citric acid would be 0.03 weight of the -13- I crushed carrots. Inactivation of enzyme was effected as in Test Example 1. After juice was obtained by a counterrotation twin-screw extruder, it was cooled.

Comparison Example Commercially available carrots, the same as used in Test Example 1, were peeled and washed with water. They were crushed into small pieces of average size 9.5mm by a crusher while they were sprayed with a 5-times diluted aqueous solution obtained from commercially available condensed lemon juice (the same as used in Test Example 4) such that the sprayed amount of citric acid would be 0.70 weight of the o:o: crushed carrots. Inactivation of enzyme was effected as in Test Example 1. After juice was obtained by a counterrotation twin-screw extruder, it was cooled.

15 Part 2 (Evaluation) Table 1 shows the juice collection efficiency (weight color, total flavor, quantity of carotinoid (mg and the result of sensory evaluation for each of the examples. The measurements and evaluations were carried out as follows: Juice Collection Efficiency (weiQht This is defined as 100 x (Quantity of juice obtained by squeezing)/(quantity of carrots before peeling).

-14- Color Hunter-type color-difference meter (Model No. ND-E80 produced by Nippon Denshoku Kogyo-sha) was used. L indicates brightness. The larger the value of L, the brighter.

Quotient a/b indicates color. The larger the value of a/b, the redder is the overall coloring.

Total flavor Gases collected by a purge and trap method were analyzed by high performance liquid chromatography, and the total area under its peak was measured. The total area for Comparison Example 1 was defined as 1.0 and relative total areas for other examples were calculated.

Quantity of carotinoid (mq Measured by high performance liquid chromatography.

15 Sensory evaluation Twenty panelists including ten men and ten women evaluated each example relative to Comparison Example 3 by a 2-point comparison method, determining which was favored. .Numbers in Table 1 indicate the number of persons who answered that the other example is preferred to Comparison Example 3. Symbols and respectively indicate significant error of 1% and 0.1%.

Comparison Examples 1 and 2 could not be evaluated because the collected amounts of juice were too small.

As clearly shown in Table 1, the favorable effects of the present invention include the following: Juice can be collected efficiently; Pigments and flavors unique to carrots can be efficiently extracted into the squeezed juice and the coloring as a whole is good; and The collected juice has no off flavor and its flavor is good as a whole.

As a result, the present invention makes it possible to produce carrot juice of high quality at an improved yield.

Table 1 Test Examples Comparison Examples 1 2 3 4 5 6 1 2 3 4 Juice Collection Efficiency (Weight 66 68 69 68 77 78 56 53 60 64 Color L 33 35 37 37 35 37 30 32 33 31 a/b 1.20 1.25 1.33 1.25 1.25 1.35 1.13 1.15 1.15 1.15 1.25 *4 Total flavor 1.4 1.5 1.7 1.7 1.5 1.7 1.0 1.4 1.3 1.4 Carotinoid S: (mg 3.8 4.7 5.3 4.7 4.9 5.5 3.6 3.6 3.8 4.0 4.7 Sensory S evaluation 16* 18** 18** 18** 18** 19** -7 -16- 16a Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

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Claims (14)

1. A method of producing carrot juice comprising the steps of: crushing or chopping carrots while spraying said carrots with an aqueous solution of citric acid or lemon juice such that the sprayed amount of citric acid from said aqueous solution or lemon juice is 0.05-0.5 weight of said carrots being crushed or chopped; effecting inactivation of enzyme by heating said crushed or chopped carrots; and squeezing said heated carrots to collect juice by means of a counter-rotation twin-screw extruder. 4 o

2. The method of claim 1 wherein said carrots are crushed or chopped to pieces of average size 3-20mm. 15 3. The method of claim 1 wherein said aqueous solution or lemon juice is sprayed such that the sprayed amount of citric acid in said aqueous solution or lemon juice is 0.1-0.2 weight of said carrots being crushed or chopped. e

4. The method of claim 2 wherein said aqueous solution or lemon juice is sprayed such that the sprayed amount of citric acid in said aqueous solution or lemon juice is 0.1-0.2 weight of said carrots being crushed or choppel. -17- The method of claim 2 wherein the step of crushing or chopping carrots is effected while simultaneously spraying said carrots with salt water, as well as said aqueous solution of citric acid or lemon juice, such that the sprayed amount of salt is 0.1-1.0 weight of said carrots being crushed or chopped.

6. The method of claim 2 wherein the step of crushing or chopping carrots is effected while simultaneously spraying said carrots with ethyl alcohol, as well as said aqueous solution of citric acid or lemon juice, such that the sprayed ~amount of ethyl alcohol is 0.5-3 weight of said carrots being crushed or chopped. 4*4* I•

7. The method of claim 2 wherein the step of crushing or chopping carrots is effected while simultaneously spraying said carrots with salt water and ethyl alcohol, as well as said aqueous solution of citric acid or lemon juice, such that the sprayed amounts of salt and ethyl alcohol are respectively 0.3-0.7 and 0.7-1.5 weight of said carrots being crushed or chopped. e•

8. The method of claim 1 wherein said step of squeezing said heated carrots to collect juice is effected in an atmosphere of nitrogen gas. -18-

9. The method of claim 2 wherein said step of squeezing said heated carrots to collect juice is effected in an atmosphere of nitrogen gas. The method of claim 3 wherein said step of squeezing said heated carrots to collect juice is effected in an atmosphere of nitrogen gas.

11. The method of claim 4 wherein said step of squeezing said heated carrots to collect juice is effected in an atmosphere of nitrogen gas. 10 12. The method of claim 7 wherein said step of squeezing said S: t heated carrots to collect juice is effected in an atmosphere of nitrogen gas. I13. The method of claim 1 wherein said counter-rotation twin- screw extruder has two shafts adapted to rotate in mutually *i 15 opposite directions, extending between an inlet end and an outlet end, each of said two shafts including a reverse screw mounted thereon nearer said outlet end than said inlet end.

14. The method of claim 2 wherein said counter-rotation twin- screw extruder has two shafts adapted to rotate in mutually opposite directions, extending between an inlet end and an -19- 1; outlet end, each of said two shafts including a reverse screw mounted thereon nearer said outlet end than said inlet end. The method of claim 3 wherein said counter-rotation twin- screw extruder has two shafts adapted to rotate in mutually opposite directions, extending between an inlet end and an outlet end, each of said two shafts including a reverse screw mounted thereon nearer said outlet end than said inlet end.

16. The method of claim 4 wherein said counter-rotation twin- screw extruder has two shafts adapted to rotate in mutually 10 opposite directions, extending between an inlet end and an outlet end, each of said two shafts including a reverse screw mounted thereon nearer said outlet end than said inlet end. S S

17. The method of claim 7 wherein said counter-rotation twin- screw extruder has two shafts adapted to rotate in mutually opposite directions, extending between an inlet end and an outlet end, each of said two shafts including a reverse screw mounted thereon nearer said outlet end than said inlet end. S 0** S0

18. The method of claim 12 wherein said counter-rotation twin-screw extruder has two shafts adapted to rotate in mutually opposite directions, extending between an inlet end and an outlet end, each of said two shafts including a reverse screw mounted thereon nearer said outlet end than said inlet end. i 21

19. A method of producing carrot juice substantially as hereinbefore described with reference to the Exam~plis (excluding the Comparative Examples).

20. Carrot juice produced by the method of any one of the preceding claims. DATED this 25th day of September, 1995 Kagome Kabushiki Kaisha By 7ts Patent Attorneys DAVIES COLLISON CAVE 950925,p.\opcirdab,Sl 800.spc,21 Abstract of tne Disclosure Carrot juice is produced by crushing or chopping carrots while spraying them with an aqueous solution of citric acid or lemon juice such that the sprayed amount of citric acid is 0.05-0.5 weight of the carrots being crushed or chopped, effecting inactivation of enzyme by heating the crushed or chopped carrots, and squeezing the heated carrots to collect juice by means of a counter-rotation twin-screw extruder. S 0** 6. *C oi* oC e* *696*