HK1031808B - Production of hydrolysate - Google Patents

Description

Production of hydrolysates

The present invention relates to a process for producing a hydrolysate, and more particularly, to a process for producing a hydrolysate by biologically hydrolyzing a protein-containing raw material.

Hydrolyzed protein has been known for centuries in the far east as a seasoning in the form of soy sauce, which has traditionally been prepared by long term fermentation, typically for several months. In the production of soy sauce, a vegetable protein-containing material such as matured soybean or defatted soybean powder is inoculated with Aspergillus together with carbohydrates, and the semi-solid product is fermented for 2 days to make koji, during which enzymes capable of hydrolyzing proteins and carbohydrates in the mash (moromi) stage are produced. Mixing the fermented koji with a solution of common salt to form a mash, allowing it to ferment with soybean lactic acid bacteria and soybean yeast for 4 to 8 months, and removing insoluble fraction from the fermented mash to obtain soy sauce.

Approximately 100 years ago, a faster method of hydrolyzing protein using hydrochloric acid for producing seasonings was developed, which required only a few hours. However, in recent years, acid hydrolyzed vegetable proteins (HPPs) have been limited in use in cooking applications due to the presence of chlorine compounds generated by the acid process. Therefore, many attempts have been made to develop HPP substitutes that can be used as cooking seasonings. Soy sauce is a suitable alternative. However, due to the differences in the raw materials and processing methods of the two products, HPP and soy sauce have many differences in their chemical composition and flavor characteristics. The amount of soy sauce that can be used as a replacement for HPP is limited due to its "fermented" flavor. Different processing procedures also result in significantly different degrees of hydrolysis of the protein-containing material to amino acids. The amino acid content of soy sauce is lower than that of HPP, resulting in soy sauce with a significantly lower consistency than HPP.

In our co-pending application EP-A-96202309.9, ｃA process for the production of ｃA seasoning is described, which process comprises preparing ｃA fermented protein koji from ｃA protein-containing material and ｃA carbohydrate, hydrolysing the fermented protein koji at 15-60 ℃ and ｃA pH of 4.5-10 for 6 hours to 28 days, characterised in that ｃA culture of lactic acid bacteriｃA at 10 ℃ is used in the stage of fermenting the protein koji or in the stage of hydrolysing³-10⁷cfu/g density of fermented protein koji.

We have now surprisingly found that certain specific lactic acid bacteria are capable of imparting to a seasoning a specific characteristic flavour, such as a meat, seafood or cereal flavour, which is stronger when inoculated with the lactic acid bacteria at the beginning of the fermentation stage than when inoculated with the same lactic acid bacteria after the fermentation stage. The hydrolysate also has a much stronger flavour than hydrolysates produced using other lactic acid bacteria. While not wishing to be bound by theory, we believe that during fermentation, certain lactic acid bacteria produce certain enzymes that convert sulfur-containing amino acids (e.g., cysteine) of protein substrates into hydrogen sulfide, which acts as a precursor for the block formed by the meat flavor.

Accordingly, the present invention provides a process for producing a hydrolysate, the process comprising fermenting a protein-containing material and a carbohydrate to form a koji; a koji for hydrolytic fermentation at 2-50 deg.C and pH5.6-7.0 for 1-20 days, characterized in that a culture of lactic acid bacteria capable of imparting a specific characteristic flavor to a seasoning is used at 10 days from the beginning of the fermentation stage³-10⁷The density of cfu/g of fermented protein koji is inoculated, said flavor being stronger when inoculated with a lactic acid bacterium at the beginning of the fermentation stage than when inoculated with the same lactic acid bacterium after the fermentation stage.

For simplicity, lactic acid bacteria capable of imparting a specific characteristic flavor to a seasoning that is stronger when inoculated with lactic acid bacteria at the beginning of a fermentation stage than when inoculated with the same lactic acid bacteria after the fermentation stage are referred to herein as specific lactic acid bacteria. Examples of suitable specific lactic acid bacteria are lactobacillus sake, lactobacillus plantarum and lactobacillus curvatus. It will be appreciated that mixtures of two or more of the specific lactic acid bacteria cultures, such as lactobacillus sake and lactobacillus plantarum, lactobacillus sake and lactobacillus curvatus or lactobacillus plantarum and lactobacillus curvatus, and the like, may be used in the present invention.

During hydrolysis, it should be clear that in general the lower the temperature the longer the time is needed and vice versa.

The fermented koji is prepared by a process similar to the conventional soy sauce process, for example, comprising inoculating a protein-containing material and a carbohydrate on a culture bed with a culture of Aspergillus oryzae and/or Aspergillus sojae in addition to a culture of the specific lactic acid bacterium to form the fermented koji. The specific lactic acid bacteria may be added before or after the culture of aspergillus, but when added after the culture of aspergillus, the specific lactic acid bacteria should be added shortly after the start of fermentation, for example within 1 hour, preferably within 30 minutes, more preferably within 15 minutes, more preferably within 5 minutes, especially within 1 minute. The protein-containing material is preferably a vegetable protein material containing a relatively high proportion of cysteine, for example 0.5-3 wt%, preferably 0.75-2 wt% cysteine, such as soy, wheat germ, corn bran or rice bran, preferably wheat bran, so that the hydrolysate has an increased sulphide content and thus an increased meat flavour. The degree of characteristic flavour (e.g. meat, seafood or cereal flavour) may also be varied by using koji substrates with different proportions of protein and carbohydrate, for example using substrates containing 30-100% protein, preferably 70-90% protein. The vegetable protein-containing material is preferably cooked and preferably used in the form of solid particles to enable aspergillus oryzae and/or aspergillus sojae to grow on the surface of the particles and eventually penetrate into the particles. The particles of the vegetable protein material may be in the form of pellets, preferably having an average diameter of 2-10mm, preferably 3-8m, especially 4-7 mm. The koji is conveniently fermented in the solid state.

During fermentation, specific lactic acid bacteria grow rapidly and at the end of fermentation at 10⁸-10⁹cfu/g levels predominate in the flora, as well as Aspergillus oryzae. The quality of the koji is clean with respect to other possible contaminants. By adding the specific lactic acid bacteria at the beginning of the fermentation, the control of the bacterial flora is always controlled so that there is no chance for the propagation of contaminants from the beginning. The high content of bacteria in the fermented koji improves the protective effect against the growth of undesirable microorganisms in the next hydrolysis step.

The hydrolysis of the fermented protein koji in the presence of water may be carried out in the absence or presence of salt, preferably with frequent stirring. Preferably, the hydrolysis is carried out at 30-37 ℃ for 2-5 days in the absence of salt, in order to maximize the enzymatic activity of Lactobacillus sake, resulting in a stronger meat flavor in the hydrolysate. When present, the salt may be present in an amount up to 100 wt% based on the weight of the fermentation starter. Optionally, two hydrolysis steps may be used, for example a first step at 4-25 ℃ for 1-48 hours followed by a second step at 25-50 ℃ for 1-20 days.

If desired, a protein containing a high proportion of cysteine, such as wheat bran, may be added additionally at the beginning of the hydrolysis to increase the meat flavour.

At the end of the hydrolysis, the reducing sugar content is very low, typically below 0.3%, so that the mash maturation process can be dispensed with. As a result, the whole production cycle can be shortened by 1 to 6 weeks.

After hydrolysis, the hydrolysed fermented koji may be pressed together with the specific lactic acid bacteria to separate the liquid sauce and the solid residue. Preferably, the liquid sauce is sterilized, for example, at 90-140 deg.C for 15 seconds-30 minutes, and then filtered to obtain the liquid seasoning. If desired, salt may be added before or after pressing or filtration to give a product having a salt content of from 0 to 60% by weight, based on the weight of the material. If desired, the liquid sauce may be powdered, for example by concentration followed by drying, such as vacuum drying, to a low moisture content and finally grinding to a powder to give a solid seasoning.

The hydrolysate produced by the process of the invention can be used as a base for flavouring agents for culinary products, in liquid, paste-like or solid form. The paste can be produced to a dry matter content of 35-55 wt%, by drying the hydrolysate and mixing with water, salt, reducing sugar, optionally adding sulphur containing amino acids or thiamine, to obtain a paste containing 24-97% hydrolysate, 2-40% salt, 1-4% reducing sugar and 0-2% sulphur containing compounds (amino acids such as cysteine or thiamine) on a dry basis. If desired, the paste-like product may be heated at 80-150 deg.C, preferably 90-110 deg.C, for 1 minute-4 hours, preferably 1-2 hours. The heated paste may then be dried to a residual moisture content of at most 2%.

The hydrolysates of the invention can be used in process flavour applications, such as beef, seafood, cereals and chicken, culinary flavours, and ingredients as HPP substitutes. When the sauce powder is reconstituted in water, the product has a lighter color, stronger taste and is more neutral than the typical fermented flavor in a standard wheat bran sauce.

The invention is further illustrated by the following examples in which parts and percentages are by weight.

Example 1

The mixture of wheat bran and wheat bran (93: 7) was mixed extruded through a Clextral extruder to give porous structured pellets with an average diameter of 5 mm.

75kg of the extruded pellets were mixed with 25kg of roasted wheat and soaked in 75kg of 75 ℃ water for 5 minutes. The soaked extruded pellets were then heated to 100 ℃ and left at the same temperature for 10 minutes before being cooled to below 40 ℃ by applying vacuum. Mixing the cooked extruded pellets with a liquid suspension of 25g of Aspergillus oryzae spore inoculum and 340g of Lactobacillus sake culture at 7X 10⁵cfu/g cooked extruded pellets were mixed.

During the 42 hours of koji fermentation, the following temperature profile was maintained for the culture bed:

0-15 hours 30 DEG C

27 ℃ for 25-42 hours

The koji was turned over at 18 and 25 hours to ensure that the bed had sufficient air flow through it for good aeration. The quality of the microorganisms during the fermentation is very good, with a total coliform count of < 10²cfu/g. After fermentation, the content of Lactobacillus sake increased to 3.3X 10⁹cfu/g。

After fermenting the koji, obtaining mature koji. Hydrolysis was carried out in a hydrolysis tank by adding water to obtain a hydrolysate with a total solids content of 20.2 m/m. Hydrolysis was carried out at 35 ℃ for 48 hours.

During hydrolysis, a rapid pH drop was observed due to the growth of lactobacillus sake (initial pH 6.4). The pH reached 6.0 after about 2 hours of hydrolysis. Thereafter, a 40% NaOH solution was metered in to maintain the pH at 6.0. It was observed that the number of lactobacillus sake in the koji was high, continued to dominate the hydrolysate and the growth of escherichia coli was again well controlled.

Finally, the hydrolysis mixture is pressed and the wheat bran sauce and the solid residue are separated. 12% m/m salt was added before pressing. The wheat bran sauce is treated at 90 deg.C for 20 min. The liquid sauce is concentrated by evaporation. The resulting concentrate was dried in a vacuum oven and then ground into a powder.

For sensory evaluation, 12.5g of liquid sauce or 3.5g of powder were diluted with 250ml of boiling water. In either case, the product was perceived to have a meat-flavored base and did not have the "fermented flavor" disadvantage. The product is very light in color and is a versatile culinary sauce.

Example 2

The procedure was similar to example 1, except that the koji prepared according to example 1 was mixed with wheat bran powder in hydrolysis (koji: wheat bran powder: 7: 3). The amount of water was adjusted so that the dry matter content of the hydrolysate was 20.2%.

A higher sulphide content in the hydrolysate was detected compared to example 1. This is because of the higher protein content (TN 13.0% by dry weight) compared to wheat bran koji alone (TN 11.3% by dry weight), resulting in a higher content of cysteine. The reduction in carbohydrate content also reduces the source of carbohydrates available for the metabolism of lactobacillus sake. As a result, more cysteine is taken up and hydrogen sulfide is produced. The hydrolysate has intense meat flavor.

Example 3

The procedure was similar to example 1, except that the carbohydrate content of the substrate used for the preparation of the koji was reduced. The mixture used was 85% wheat bran, 5% wheat bran and 10% wheat flour. Inoculating Lactobacillus sake and Aspergillus oryzae in the cured substrate. The microbial results show that the growth of lactobacillus sakei is not affected by the reduction of the carbohydrate formulation. A higher sulphide content was detected compared to example 2 and the hydrolysate had a strong meat flavour.

Example 4

The preparation process was similar to example 3, except that no salt was added to the hydrolysate to obtain a salt-free sauce or powder with a strong meat flavor.

Example 5

The procedure was analogous to example 1, except that hydrolysis was carried out at 22 ℃ for 10 days. A salt-free sauce or powder with a strong meat flavor is obtained.

Example 6

The procedure was similar to example 3, except that hydrolysis was extended to 5 days to increase the degree of hydrolysis. A salt-free sauce or powder with a strong meat flavor is obtained.

Example 7

The procedure was similar to example 2 except that corn gluten meal was used instead of wheat gluten meal. A salt-free sauce or powder with a strong meat flavor is obtained.

Example 8

The dried hydrolysate described in example 1 was used as a base for flavouring agents for culinary products. Flavoring agents were prepared by mixing 47.8 parts of powdered hydrolysate with 17.0 parts water, 13.3 parts salt, 8.3 parts yeast extract, 1.1 parts cysteine, 1.1 parts thiamine, 0.8 parts glucose and 0.1 parts onion extract. The paste was heated in a double jacketed kettle at 100 ℃ for about 90 minutes and dried under reduced pressure at 15 mbar to a dry matter content of 98%.

Example 9

The procedure was similar to example 1, except that a culture of Lactobacillus plantarum was inoculated instead of Lactobacillus sake. The product has a marine product flavor and no 'fermented flavor' defect.

Example 10

The procedure was similar to example 1, except that L.curratus culture was inoculated instead of Lactobacillus sake. The product has a grain flavor different from wheat bran and does not have the defect of fermented flavor.

Example 11

The procedure was similar to example 1, except that a mixed culture of Lactobacillus sake and Lactobacillus plantarum was inoculated instead of Lactobacillus sake. The product has a meat flavor different from wheat bran and does not have the defect of "fermented flavor".

Example 12

The procedure is similar to example 1, except that the hydrolysis is carried out first at 20 ℃ for 10 hours and then at 35 ℃ for 4 days.

Comparative examples

The procedure was similar to example 1, except that the pH of the hydrolysis was kept fluctuating, i.e.no pH adjustment was carried out. The pH of the hydrolysate dropped to 4.5 after 4 hours of hydrolysis. After 8 hours of hydrolysis, the pH was adjusted to 6 and maintained during the subsequent hydrolysis. With this pH profile, the sulfide content during the 48 h hydrolysis was negligible. The corresponding sauce had a meat flavor that was inferior to the product of example 1.

The above results indicate that the pH should be at least above 5.6 during the growth phase of Lactobacillus sake (hydrolysis for about 2-8 hours).

Claims (21)

1. A process for producing a hydrolysate, the process comprising fermenting a protein containing material and a carbohydrate to form a koji; a koji for hydrolytic fermentation at 2-50 deg.C and pH5.6-7.0 for 1-20 days, characterized in that a culture of lactic acid bacteria capable of imparting a specific characteristic flavor to a seasoning is used at 10 days from the beginning of the fermentation stage³-10⁷The density of cfu/g of fermented protein koji is inoculated, said flavor being stronger when inoculated with a lactic acid bacterium at the beginning of the fermentation stage than when inoculated with the same lactic acid bacterium after the fermentation stage.

2. The method of claim 1, wherein the lactic acid bacteria are Lactobacillus sake, Lactobacillus plantarum and Lactobacillus curvatus, or a mixture of two or more thereof,

3. the method of claim 1, wherein the fermentation starter is prepared by inoculating a protein-containing material and a carbohydrate on a culture bed with a culture of Aspergillus oryzae and/or Aspergillus sojae in addition to a culture of the specific lactic acid bacteria.

4. The process of claim 1 wherein the protein-containing material is a vegetable protein material having a high content of cysteine.

5. The method of claim 1 wherein the protein-containing material is soybean, wheat germ, corn bran, rice bran, or wheat bran.

6. The method of claim 1, wherein the protein-containing material is a substrate containing 30-100% protein.

7. The method of claim 1, wherein the protein-containing material comprises 70-90% protein.

8. The process of claim 1 wherein the protein-containing material is matured and used in the form of solid particles to enable Aspergillus oryzae and/or Aspergillus sojae to grow on the surface of the particles and eventually penetrate into the particles.

9. The method of claim 1, wherein the protein-containing feedstock is fermented in the solid state.

10. The process of claim 1, wherein the hydrolysis of the fermented protein koji in the presence of water is carried out in the absence or presence of salt.

11. The process of claim 1, wherein the hydrolysis is carried out in the absence of salt at 30-37 ℃ for 2-5 days.

12. The method of claim 1, wherein the salt, when present, is present in an amount up to 100 wt% based on the weight of the fermentation broth.

13. The process of claim 1, wherein the hydrolysis is carried out in two steps comprising a first step at 4-25 ℃ for 1-48 hours, followed by a second step at 25-50 ℃ for 1-20 days.

14. The process of claim 1, wherein a protein containing a high proportion of cysteines is additionally added at the beginning of the hydrolysis.

15. The process of claim 1, wherein after hydrolysis, the hydrolyzed fermentation starter is pressed together with a culture of a specific lactic acid bacterium to separate a liquid sauce and a solid residue.

16. The method of claim 15, wherein the liquid sauce is sterilized at 90-140 ℃ for 15 seconds to 30 minutes and then filtered to obtain the liquid seasoning.

17. The process of claim 15, wherein salt is added before or after pressing to obtain a product having a salt content of 0-60 wt% based on dry matter weight.

18. The method of claim 15 wherein the liquid sauce is powdered by concentration, then dried to a low moisture content, and finally ground into a powder to provide a solid seasoning.

19. A process for the preparation of a paste having a dry matter content of from 35 to 55% by weight for use as a flavour base for culinary products, which process comprises drying a hydrolysate prepared by the process of claim 1 and mixing with water, salt, a reducing sugar, optionally with the addition of a sulphur-containing amino acid or thiamine, to give a paste containing from 24 to 97% hydrolysate, from 2 to 40% salt, from 1 to 4% reducing sugar and from 0 to 2% sulphur-containing amino acid or thiamine on a dry basis.

20. The method of claim 19, wherein the paste is heated at 80-150 ℃ for 1 minute-4 hours.

21. A process for the preparation of a dry hydrolysate for use as flavouring base for culinary products, which process comprises drying a paste obtained according to claim 18 to a residual moisture content of at most 2%.