CA1208586A - Low d.e. starch hydrolyzates - Google Patents

Abstract

LOW D.E. STARCH HYDROLYZATES
Abstract of Disclosure Low D.E. starch hydrolyzates which can be readily filtered are obtained from non-waxy starches by treatment with bacterial alpha-amylase for an extended period at a temperature above about 95° C.

Description

Z~ 6 ., LOW D . E . STARCH HYDROLYZATES
This invention relates to starch hydrolyzate products and to preparation of such products.
It is known that starch can be hydrolyzed by means of acids or enzymes to produce hydrolyzate products containing sugars and which therefore are useful in foods. The sweetening property of the starch hydrolyzates depends to great extent upon the degree of conversion, that is, the extent to which the starch molecules have been hydrolyzed. A very common method of classifying starch hydrolyzates is to measure the deyree of h~drolysis in terms of dextrose equivalent (D~Eo) which is a measure of the reducing sugar content of the hydrolyzate calculated as dextrose and expressed as a per-centage of the total dry substance. The dextrose equivalent (D.E.) value of a starch hydxolyzate can be determined conveniently by the method of Smogyi, M. described in the Journal of Biological Chemistry 160, 61 (1945) and is the method utilized herein for determining D.E. values.
The use of enzymes for hydrolyzing starch has gained widespread application in recent years and enzymes are employed commercially for manufacturing certain products. Enzymes have an advantage over acid ca~alysts in that they exhibit speci-ficity for certain linkages. One type of microbial enzyme which is commonly employed is alpha-amylase. Alpha-amylase has the property of splitting 1-4 linkages more or less at random throughout the starch molecule with little effect on - ~ ~2~

the 1-6 linkages. Moreover, alpha-amylase does not readily hydrolyze or split the 1-4 linkage in maltose and maltotriose.
Thus, it has been reported that when substantially complete conversion of starch is effected with alpha-amylase, maltose and small amounts of trisaccharides and other lower molecular weight polysaccharides, especially those containing the 1-6 linkages, are present in the final hydrolyzate.
Low D.E. starch hydrolyzates are widely used by the food industry as bodying agents and carriers for food flavors, etc. For many applications the functionality or suitability is enhanced when the D.E. of the hydrolyzate is relatively low. Thus, low D.E. starc~ hydrolyzates generally exhibit viscosity, film-forming and low sweetness properties which are particularly desired for certain applications.
Although the advantages of hydrolyzates with D.E. values less than 10 have been long recognized by the food industry, previous attempts to produce a refined hydrolyzate of non-waxy starch in this D.E. range have been hampered due to the inability to filter the hydrolyzates. Unusual difficulty in filtering such low D.E. products has been a serious problem in the past. Non-waxy low D.E. products have been produced as unrefined hydrolyzates, l.e., unfiltered products, but such products have had limited usage because of incomplete solubility and a marked tendency to hecome rancid with off flavors and odors duxlng storage.
This invention involves the discovery that low D.~. starch hydrolyzates having D.~. values of about 6 and lower can be produced and filtered and refined by an extended treatment with alpha-amylase at tem~eratures of ahout 95 C.
and above. In accordance wi~h a presently ~reEerred e~bodi-ment of this invention, a non-waxy starch is clis~ersed in water at a level of 10-40~ solids, preferably ~n the range of 20-30~ solids, and liquefied by heating with either acid or a liquefying enzyme as described in U.S. patent No. 3,663,369. Whichever method of liquefaction is used, it -` 12V~35~6 is important that the liquefaction be carried out so as to provide complete gelatinization with essentially no residual starch ~ranules, with the liquefied starch having a D.E. of not substantially above 3. The pH of the liquefied starch is adjusted to a pH value between about 6.5 and 8.0, prefer-ably between 6.8 and 7.5. Bacterial alpha-amylase is added to the liquefied starch which is adjusted to and maintained at a temperature of about 95 C. or above, preferably at a temperature of about 95-100 C., for a period of 10 to 60 minutes. When the desired D.E. is reached, l.e. preferably between 3 and 6, the hydrolyzate is acidified to a pH below 4.5, preferably between 3.5 and 4.0, to inactivate the enzyme, and the hydrolyzate recovered by filtration. The hydrolyzate can then be treated with carbon and dried using procedures common to the art.
Thus, the invention provides a process for producing a starch hydrolyzate which comprises treating an aqueous slurry of non-waxy starch with an acid or enzyme to liquefy the starch and to provide an aqueous dispersion substantially ~0 free of residual starch granules with a measurable dextrose equivalent value not substantially above 3, then treating the said dispersion with a bacterial alpha-amylase at a temperature at least about 95 C. to produce a hydrolyzate product having a measurable dextrose equivalent value not substantially above 10, stopping the enzyme action and re-covering the hydrolyzate so produced. Furthermore, the invention involves a non-waxy starch hydrolyzate having a measurable dextrose equivalent value not substantially above 6, a saccharide composition wherein the amount of glucose pre~ent is less than about 1~ and the amount of maltose is less than about 1.5%, and a descriptive ratio of less than 2, said hydrolyzate being further characterized as being filter-able and substantially completely soluble in water at 80 C.
at solids concentrations below 35% by weight.

~L2(~8~6 The use of an extended treatment with alpha-amylase at temperatures at least about 95 C. is a critical feature of the present invention. Whereas the prior art has taught the use of alpha-amylase at temperatures over 93 C. for brief periods to accomplish liquefaction, the conventional practice has been to reduce the temperature after liquefaction to below 85 C. to maximize the rate of hydrolysis as measured by D.E. increase. Under these conditions the hydrolyzate is essentially unfilterable until the D.E. has reached a value of 8 or higher. We have now discovered that treating the liquefied starch with alpha-amylase ?t a temperature of 95 C. or higher produces an unexpected improvement in filterability with very little increase in D.E. This discovery, that filterability of hydrolyzates of 6 D.E. and lS lower is enhanced by extending the time of amylase treatment at 95 C. or above while the rate of D.E. increase is slowed down, is the feature of the present invention which allows the recovery of refined low D.E. hydrolyzates of non-waxy starch which have not previously been available.
A variety of non-waxy starch or amylaceous materials can be employed in accordance with the invention, such as, for example, potato, white sweet potato, grain sorghum, tapioca, 121J8S~6 wheat, rice, sago and the like. Corn starch is a preferred material.
The type of alpha-amylase suitable for carrying out the pr~sent invention is we~l known to the art and is 5 available commercially under such names as Biocon Canalpha 180, Miles Tenase, or Novo BAN. These are bacte~ial enzymes produced by Bacillus subtilis. Another type of bacterial alpha-amylase which may be used is produced by cultures of Bacillus licheniformis and is available commercially under the name Novo Termamyl and Miles Taka-Therm. Amylases derived from Bacillus licheniformis have a higher sacchari-fying activity above 95 C. than amylases derived from _cillus _btilis and therefore are more difficult to contrGl to provide a final D.E. of 6 or less.
The level of alpha-amylase suitable for carrying out the present process is generally in the range of 0.1 to 0.6~ based on starch solids when a commercial enzyme product such as the ones listed above is employed. The e~:act level employed will depend on the final D.E. desired, the enzyme activity and the temperature and pH of the reac-tion. If the final D.E. desired is in the range of 3-4, it is ~referred to use a slightly higher temperature and pH, 1._. 97 C., pH 7.5, which requires a higher level of alpha-amylase to provide maximum filterability than would be requ,ired to obtain a 6 D.~. product at a lower temperature and pH, l.e. 95 C., pH 7Ø Usually for the preparation of hydrolyzates in the 4-6 D.E. range, we find that 0.2 to 0.4~ alpha-amylase assaying 3,000 to 4,000 SKB unit per ~ram gives satisfactory results.
The reaction time and temperature are closely l~lated; l.e., within the relatively narrow temperature range that the invention may be carried out t an increase in temperature shortens the time to attain maximum filter-ability. For the preparation of products in the less than 6 D.E. range a reaction time of 20 minutes at 95 C. is -` lZ(~85~

usually sufficient to provide a filterable hydrolyzate, although the time may be as short as 5 minutes or as long as 40 minutes.
- The hydrolyzates of the present invention are superior to non-waxy starch hydrolyzates of the prior art, primarily with respect to better solubility and clarity of aqueous solutions at comparable D.E. values below 6. ~hereas non-waxy products of 6 D.E. and below of the prior art are virtually unfilterable, the new low D.E. hydrolyzates of the invention can ~e easily filtered and treated with carbon to provide products which are su~stantially completely soluble in water with the solutions being essentially colorless, odorless and tasteless. The hydrolyzates of the present invention have very low levels of the lower saccharides as shown by the data in Example 5. The clarity stability is substantially improved over products prepared by prior art processes as shown by the data in Example 4. The new low D.E. starch hydrolyzates may be characterized as follows:
1. A low D.E. of 6 or less.

2. Completely soluble in water at 80 C. at all solids concentra-tions below 35~.

3. Clarity of 30~ solutions at 80 C.
measured against water in a 19 millimeter cell at 600 m~ exceeds 60~ light transmittance.

4. Contain less than 1.0~ monosaccharide and less than 1.5~ disaccharide and a descriptive ratio, calculated by dividing sum of DPl DP6 saccharides by D.E., of less than 2.

5. Can be filtered at good filtration rate6, i.e. at rates in excess of 100 milliliters per minute. (See Example 1.) ~2~3S~6 The following examples further illustrate the invention and the advantages thereof.

_YMP E 1 Two 3-liter samples of acid-liquefied, non-waxy corn starch were obtained from a co~nercial jet cooker. The liquefied starch contained 25% solids, had a pH of 7.2 and a D.E. of 2.2. One sample was held at 80 D C . and the other at 96~ C. Bacterial alpha-amylase (Canalpha~180) was added to both samples at a level of 0.2% based on starch solids. This level was equivalent to 800 SKB units of alpha-amylase per 100 grams of staroh. Two hundred milliliter portions were removed at 5, 10, 20, 30 and 40 minutes, acidified to pH
3.5 4.0, and checked for filterability by the following test:*
A 9 centimeter, jacketed, filtering funnel heated with circulating water at 80 C. was equipped with ~1 Whatman filter paper and attached to an aspirator. Two grams of filteraid (Celatom) was added to 200 milliliters of crude hydrolyzate at 75-77 C. and poured into the funnel. A
stop watch was used to measure the time to filter the entire samE~le or the volume filtered in 5 minutes. The filtration time was used to calculate the filtration rate in milliters per minute.
The results comparing alpha-amylase treatment at 80 and 96~ C. are reported below. It is readily apparent that the rate of D.E. increase is much higher at 80 C. than at 96 C. while the filtration rate is much higher after amylase treatment at 96 C. than at 80 C.

~ _ __ __ ___ ~ __ __ _ _ * This test method is used throughout to obtain data on filtration.

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~1 g A six-liter sample of acid-liquefied starch, 23.3~ solids, was obtained from a production jet cooker and divided into two 3-liter samples for treatment with Biocon Canalpha~180 alpha-amylase as shown below. One sample was held at 80 C. and the other at 95 C~ Samples , were removed periodically for measurements of D.E. and filterability after adjusting to pH 3~5-4.0 to inactivate enzyme.

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The results show that the D.E. increased fastest in the 80~ C. sample; however, the filtra ion rate increased faster at 95 C.

A dispersion of non-waxy starch was treated with alpha-amylase and liquefied in a commercial jet cooker. Two samples of liquefied starch were adjusted to pH 7.0 and heated to 80 C. and 95 C. for treatment with alpha-amylase as follows:

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The results show that D.E. increased faster at S0 C. than at 95 C. while the filtration rate for the low D.E. products (~ 6) was much faster using a 95 reaction temperature than at 80 C. For example, at 80~ the D.E.
reached 5.88 after 5 minutes and provided a filtration rate of 81 milliliters per minute. At 95 the D.E. reached 5.6 , at 30 minutes and had a filtration rate of 160 milliliters per minute.

Four 3-liter samples of acid-liquefied starch were drawn from a commercial, steam jet cooker. The liquefied starch contained 22% solids and had a D.E. of 2.2. The p~l was adjusted to 7.2 and the temperature held at 85, 90, 95 and 99 C. as shown below. Alpha-amylase (Biocon Canalpha 15 180) was added at a level of 0.3% based on solids. Samples were removed periodically, acidified with hydrochloric acid to pH 4 and tested for filterability using the Standard Filtration Test described previously. A portion of the filtrate was used to determine D.E. and checked for clarity after heating to 80 C., then cooling to 60 C. Ciarity was determined by measuring the light transmittance against water at 600 m~u using a 19 millimeter B~L test tube ln a Spectronic 20 Colorimeter.
The results are given in the table below. The data show that treatment with alpha-amylase at temperatures of 95 or 99 C. produced filtrable hydrolyzates in the 3-5 D.E. range while at 85u filterable products were not obtained until thc D.E. reached 6 or 7. The clarity data show that increasinc3 the temperature of amylase treatment from 85 to 3G ~'3 produced a substantial improvement in c~arity stability of samples in the 3-6 D.E. range.

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~1 m o a a~l lZ(~85~36 Scveral samples of non-waxy hydrolyzates with D.~.'s between 4 and 6 were prepared by the process of the invention and analyzed for D.~. and saccharide profile as shown in the following table, - lZ~S~36 ,1 CL O O ~r ~ ~ _l o U~
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Z U _1 m ~ a ~ a a ~q tl lZq~8586 Three liters of acid-cooked starch paste from a production steam jet cooker were adjusted to pH 7.0 with sodium carbonate and cooled to 96 C. Forty-eight milli-liters of diluted Biocon Canalpha bacterial alpha-amylase (equal to 0.4~ on starch dry substance) were added and the solution held at 95-96 C. for 27 minutes. Hydrochloric acid was added to adjust the pH to 4.2 and 2.5 grams carbon added.
After 10 minutes at 95 C., the solution was cooled to 85 C. and filtered with the aid of a filter aid. The filtrate was water-clear at temperatures above 75~ C. and had a D.E. of 4.3.
Those modifications and equivalents which fall within the spirit of the invention are to be consldered a part thereo~.

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Claims (16)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for producing a starch hydrolyzate which comprises treating an aqueous slurry of non-waxy starch with an acid or enzyme to liquefy the starch and to provide an aqueous dispersion substantially free of residual starch granules with a measurable dextrose equivalent value not substantially above 3, then treating the said dispersion with a bacterial alpha-amylase at a temperature at least about 95° C. to produce a hydrolyzate product having a measurable dextrose equivalent value not substantially above 10, stopping the enzyme action and recovering the hydrolyzate so produced.

2. A process in accordance with claim 1 wherein the treatment with a bacterial alpha-amylase is carried out at a temperature in the range from about 95 to 100° C.

3. A process in accordance with claim 1 wherein the treatment with the bacterial alpha-amylase is carried out at a pH between about 6.5 and 8.

4. A process in accordance with claim 1 wherein treatment with bacterial alpha-amylase is carried out at a temperature from about 95 to 100° C. and at a pH of from about 6.5 to 8.

5, A process in accordance with claim 1 wherein treatment with bacterial alpha-amylase is carried out at a temperature from about 95 to 100° C. and at a pH of from about 6.8 to 7.5.

6. A process in accordance with claim 1 wherein a starch hydrolyzate product having a measurable dextrose equiva-lent value not substantially above 6 is recovered.

7. A process in accordance with claim 6 wherein the starch hydrolyzate product is recovered by filtration.

8. A process in accordance with claim 6 wherein the starch hydrolyzate product is recovered by filtration and then treated with carbon to obtain a refined starch hydrolyzate product.

9. A process in accordance with claim 1 wherein a starch hydrolyzate product having a measurable dextrose equivalent value of from about 3 to about 6 is recovered.

10. A process in accordance with claim 9 wherein the starch hydrolyzate product is recovered by filtration.

11. A process in accordance with claim 9 wherein the starch hydrolyzate product is recovered by filtration and then treated with carbon to obtain a refined starch hydrolyzate product.

12. A non-waxy starch hydrolyzate having a measurable dextrose equivalent value not substantially above 6, a saccharide composition wherein the amount of glucose present is less than about 1% and the amount of maltose is less than about 1.5%, and a descriptive ratio of less than 2, said hydrolyzate being further characterized as being filter-able and substantially completely soluble in water at 80° C.
at solids concentrations below 35% by weight.

13. A starch hydrolyzate in accordance with claim 12 wherein the starch hydrolyzate has a measurable dextrose equivalent value of about 3 to about 6.

14. A starch hydrolyzate product in accordance with claim 13 which provides essentially colorless, odorless and tasteless aqueous solutions.

15. A refined non-waxy starch hydrolyzate having a measurable dextrose equivalent value not substantially above 6 and a saccharide composition wherein the amount of glucose present is less than about 1% by weight and the amount of maltose is less than 1.5% by weight, and a descrip-tive ratio of less than 2, said hydrolyzate being refined by filtering and treatment with carbon and being substantially completely soluble in water at 80° C. at solids concentrations below 35% by weight.

16. A refined non-waxy starch hydrolyzate in accordance with claim 15 wherein the hydrolyzate has a measurable dextrose equivalent value of about 3 to 6.