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Title:
FUNCTIONAL INGREDIENTS FROM ENZYME-MODIFIED WHEAT PROTEINS
Document Type and Number:
WIPO Patent Application WO/2015/131226
Kind Code:
A1
Abstract:
A method of producing an ingredient material for use in food, said method including the steps of transforming a parent gluten complex by two or more enzymatic processes whereby said ingredient material displays different physical and functional properties to said parent gluten complex.

Inventors:
PEARCE, Robert, John (1 James Lane, Kiama, NSW 2533, AU)
BARRIE, Amy, Lee (5 Hanover Close, South Nowra, NSW 2541, AU)
Application Number:
AU2015/000113
Publication Date:
September 11, 2015
Filing Date:
March 02, 2015
Export Citation:
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Assignee:
SHOALHAVEN STARCHES PTY LTD (36 Bolong Road, Bomaderry, NSW 2541, AU)
PEARCE, Robert, John (1 James Lane, Kiama, NSW 2533, AU)
BARRIE, Amy, Lee (5 Hanover Close, South Nowra, NSW 2541, AU)
International Classes:
A23J3/34; A21D2/26; A23J3/18; A23L1/305; A23L2/66; C12P21/06
Domestic Patent References:
2002-01-10
2001-10-18
Foreign References:
US20020106424A12002-08-08
US20120288587A12012-11-15
Other References:
LEE, S. E. ET AL.: "Effects of enzymatic modification of wheat protein on the formation of pyrazines and other volatile components in the Maillard reaction", FOOD CHEMISTRY, vol. 131, no. 4, 2012, pages 1248 - 1254, XP028118842, ISSN: 0308-8146
SCHLICHTHERLE-CERNY, H. ET AL.: "Analysis of Taste-Active Compounds in an Enzymatic Hydrolysate of Deamidated Wheat Gluten", J. AGRIC. FOOD CHEM., vol. 50, no. 6, 2002, pages 1515 - 1522, XP055222670, ISSN: 0021-8561
DATABASE WPI Week 201309, Derwent Publications Ltd., London, GB; Class d13, AN 2012-L42450, DWPI
Attorney, Agent or Firm:
ANDERSON-TAYLOR, Michael (P.O. Box 710, Cronulla, NSW 2230, AU)
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Claims:
The claims defining the invention are as follows:

1. A method of produc ing an ingredient material for use in food, said method including the steps of transforming a parent gluten complex by two or more enzymatic processes whereby said ingredient material displays different physical and functional properties to said parent gluten complex.

2. The method as claimed in claim 1 wherein said enzymatic processes occur sequentially,

3. The method as claimed in claim 1 wherein said enzymatic processes occur concurrently.

4. The method as claimed claim 1 wherein in one of said enzymatic

processes the parent gluten complex is fragmented by enzymatic hydrolysis.

5. The method as claimed in claim 4 wherein in another subsequent one of said enzymatic processes fragmented gluten is changed by enzymatic hydrolysis of a proportion of a glutamine constituent of peptides and conversion thereof into glutamic acid.

6. The method as claimed in claim 5 wherein said fragmented gluten is

separated according to size, charge or solubility

7. The method as claimed in claim 1 wherein said enzymatic processes

include enzymatic proteolysis of a vital wheat gluten followed by separation of soluble from insoluble peptides followed by enzymatic deamidation of soluble peptides.

8. The method as claimed in claim 6 wherein said fragmented gluten is dried by any suitable means.

9. The method as claimed in claim 7 wherein said fragmented gluten is dried by spray drying.

10. The method as claimed in claim 1 wherein said parent gluten complex is a vital wheat gluten.

11. The method as claimed in claim 9 wherein said one of said enzymatic processes uses a commercial tryptic-like enzyme of fungal origin and said another subsequent one of said enzymatic processes uses a protein- deamidase enzyme.

12. A method of producing an ingredient material for food, said method being substantially as described herein with reference to the examples.

13. A food product which includes the ingredient material produced by the method as claimed in claim 1.

14. The food product as claimed in claim 12 wherein said food product is a dough or batter in which the elasticity, extensibility and viscosity is enhanced by said ingredient material.

15. The food product as claimed claim 12 wherein said food product is a meat product or meat analogue product in which the inclusion of water and fat components is enhanced by said ingredient material.

16. The food product as claimed in claim 12 wherein said food product is a liquid food or beverage in which the inclusion of water and fat

components is enhanced by said ingredient material.

17. The food product as claimed in claim 12 wherein said food product is a non-dairy fat powder or a non-dairy creamer in which emulsion stability is enhanced by said ingredient material.

Description:
FU NCTIONAL I NGREDI ENTS FROM ENZYM E-MODI FIED

WH EAT PROTEI NS

FIELD OF THE INVENTION

The present invention relates to novel products derived from wheat gluten that can be used advantageously as food ingredients in a range of foods additional to traditional uses for gluten as in bakery goods, pasta and noodles. Additionally the present invention relates to the process of making the aforesaid novel products and applications for such novel products in foods.

BACKGROUND TO THE INVENTION

Wheat protein occurs mostly as a complex of gliadin and glutenin proteins which when extracted from wheat flour with water forms a water-insoluble, viscoelastic mass known as gluten. It is this property and material that renders wheat flour uniquely suitable for making leavened bread, pasta, noodles and other food items prepared from a wheat flour-based dough or batter. It is also this material and property that restricts the use of wheat protein in most other manufactured food formulations.

As the protein most-extensively-grown globally for human food and with the globe facing a food and protein shortage, there is a need to discover and develop wheat protein derivatives to find wider usage in more specialised and versatile ingredient forms. To this end for more than 20 years researchers have sought physical, chemical and biological solutions to this challenge.

Thermal treatment of gluten, often traded as Vital Wheat Gluten, brings about the well-established change to its structure and properties known as devitalisation. In this process, elasticity and cohesiveness is lost and the protein mass shows a higher affinity for water due to changes in the secondary, tertiary and quaternary structures of the protein complex. Apart from use as a proteinaceous filler in some foods especially meat sausage-type products, as an ingredient devitalised gluten offers little advantageous functionality.

While the structure of the gluten complex is not fully understood, several models have been proposed and in every one, disulphide cross links play an important role in maintaining structural integrity and in conferring aspects of strength and elasticity to the viscoelastic behaviour. Consequently, chemical treatments of gluten to break or realign disulphide cross links have been described to change and enhance the properties of gluten, see for example, Shewry, P.R. & Mifiin, B.J. (1985) Seed storage proteins of economically important cereals Adv.Cer.Sci Technol 7, 1-83

Wheat gluten is unique amongst proteins in its viscoelastic properties that are related to the primary structures of the separate proteins of the gluten complex. The uniqueness in composition is conferred via the extremely high content of the amino acid glutamine representing more than one-third of all amino acids. Glutamine side chains off the main peptide backbone of the proteins confer a high degree of hydrophilicity but a low level of electrically charged sites on the protein surface. Together wit h an high content of the structure-imposing amino acid, proline, and a quite high level of apolar amino acid side chains and low content of ionisable amino acid side chains results in high water affinity but very low water solubility.

Understandably, glutamine side chains have been the target for modification of wheat gluten for enhancement of functional properties. Deamidation of glutamine results in the formation of glutamic acid, an ionisable amino acid side chain which is also a natural but non-essential amino acid, so the intrinsic nutritional value of the protein is not changed. The process of chemical deamidation via acid- or alkali- catalysed hydrolysis has been reviewed by William E. Riha III, Henry V Izzo, Jie Zhang and Chi-Tang Ho (1996) Nonenzymatic Deamidation of Food Proteins Critical Reviews in Food Science and Nutrition, 36(3), 225-255.

Deamidation of wheat proteins has been described by Matsudomi,N., Kato, A and obayashi, K. (19820 Conformation and properties of deamidated gluten.

Agricultural and Biological Chemistry 46(6), 1583-1586.; Mimouni, B., Raymond, J., Merledesnoyers, A.M. Azanza, J.L and Ducastaing, A.(1994) Combined acid deamidation and enzymatic hydrolysis for improvement of the functional properties of wheat gluten. Journal of Cereal Science 20(2) 153-165); Ahmedna, M.,

Prinyawiwatkul, W. and Rao, R.M. (1999) Solubilised wheat protein isolate;

functional properties and potential food applications. Journal of Agricultural and Food Chemistry, 47(4), 1340-1345, and shown to markedly improve its solubility. Deamidated wheat protein has been shown also to have good emulsification properties comparable to other food proteins used as emulsifiers including casein, casemates and soy protein isolate by Ahmedna, M., Prinyawiwatkul, W. and Rao, R.M. ( 1999) Solubilised wheat protein isolate; functional properties and potential food

applications. Journal of Agricultural and Food Chemistry, 47(4), 1340-1345, and by Webb, M.R. , Naeem, H.A. and Schmidt, K.A. (2002) Food protein functionality in a liquid system; a comparison of deamidated wheat gluten with dairy and soy proteins Journal of Food Science 67(8) 2896-2902, and the mechanism of emulsion stabilisation by deamidated wheat protein has been described by Li Day, Mi Xu, Leif Lundin and Tim j. Wooster (2009) Interfacial properties of deamidated wheat protein in relation to its ability to stabilise oil-in- water emulsions. Food Hydrocolloids April, 1-10

Chemically-deamidated wheat proteins have been available in the global marketplace for a number of years; early popularity due to excellent functionality properties, particularly improved solubility, as food ingredients gave way to other materials as chemically deamidated wheat protein became less well regarded due to unpleasant flavour generation and to acid-deamidated wheat protein products being implicated in new allergen sensitivities.

As the advantageous improved solubility was counteracted by adverse flavour and health issues, alternative means of modifying gluten have been investigated and disclosed. US Patent 6,610,334 discloses the use of thiol redox proteins for reducing protein intramolecular disulphide bonds for improving the quality of cereal products, dough and baked goods.

Enzyme treatment of proteins with protease enzymes has for some time been used to increase their solubility as described by J. Adler-Nissen (1976) Enzymic hydrolysis of proteins for increased solubility. Journal of Agricultural and Food Chemistry 24(6) 1090-1093. More recently, Qi Wei and He Zhimin (2006) Enzymatic hydrolysis of proteins: mechanism and kinetic model. Chem. China 3, 308-314, have described a mechanism and kinetic model for the enzymatic hydrolysis of proteins particularly in regard to the release of active peptides from proteins. Xiang Dong Sun (201 1 ) describes the enzymatic hydrolysis of soy proteins in

Enzymatic Hydrolysis of Soy Protein and the Hydrolysates Utilisation International Journal of Food Science & Technology 46(2),2447-2459 and the advantageous utilisation of soy protein hydrolysates in changing functional properties and improving nutrition. US Patent Xiang Dong Sun (201 1 ) describes the enzymatic hydrolysis of soy proteins in Enzymatic Hydrolysis of Soy Protein and the

Hydrolysates Utilisation International Journal of Food Science & Technology 46(2),2447-2459 discloses a partial hydrolysate of whey protein which contains active peptides but does not have a bitter flavour. US Patent 8, 101,377 discloses an alternative method of controlling flavour and minimising bitterness in dairy protein hydrolysates by commencing the process with protein in basic solution at pH about 10.4, cooling the solution and then adding protease enzyme that is allowed to function over an extended period.

In US Patent 5,945,299 is disclosed a process for producing wheat protein

hydrolysates in a multi-stage hydrolysis with both a proteinase and a peptidase in order to prevent instability in solution recognised as clouding. By this process a more favourable molecular weight distribution of peptides is achieved. The process includes use of a proteinase first at acidic pH then at alkaline pH and thirdly with peptidases at pH6-7.

US Patent 6,036,983 discloses a method of obtaining protein hydrolysates useful as flavouring agents. It is well known that extensive hydrolysis of proteinaceous materials results in flavoursome products that may be used in soups, sauces and seasonings. Furthermore, it is known that the amino acid glutamine (gin) is almost tasteless whereas glutamic acid (glu) whether free or peptide bound plays an important role for the flavour and palatability of protein hydrolysates. The process of deamidation converts glutamine to glutamic acid and can be achieved by non- enzymatic hydrolysis with acids or alkalis as described above. US Patent 6,036,983 teaches the use of of peptidoglutaminases such as Peptidyl-glutaminase EC 3.5.1.43 or Protein-glutamine glutaminase EC3.5.1.44 for enzymatic deamidation of peptides.

US Patent No 3,857,967 discloses a process for the preparation of a food or beverage with a peptidoglutaminase from Bacillus circiilans but in order to achieve the greatest degree of deamidation , US Patent No 3,857,967 teaches initial degradation of the proteinaceous substrate by use of non-specific endo- and/ exo-peptidases

Mimouni et al Mimouni, B., Raymond, J., Merledesnoyers, A.M. Azanza, J.L and Ducastaing, A.(1994) Combined acid deamidation and enzymatic hydrolysis for improvement of the functional properties of wheat gluten. Journal of Cereal Science 20(2)153-165, describe a combined acid deamidation and enzymatic proteolysis using non-specific endo-peptidases.

US Patent No 7,846,709 discloses a protein-deamidating enzyme recovered from Chryseobacterium proteolyticum, the gene encoding for the same and a process for its production. The enzyme is described further in Yamaguchi, S. & Yokoe, M. (2000) A novel protein deamidating enzyme from Chryseobacterium proteolyticum sp. , a newly isolated bacterium from soil. Appl. Environ. Microbiol. 66, 3337-3343.

The action of protein-glutaminase has been studied on several proteins: Gu,

Y.S.,Matsumura, Y., Yamaguchi, S. & Mori, T. (2001) Action of protein-glutaminase on alpha- lactalbumin in the native and molten globule states J. Agric. Food Chem. 49, 5999-6005; Yong,Y.H., Yamaguch, S., Gu, Y.S.,Mori, T, & Matsumura, Y.

(2004) Effects of enzymatic deamidation by protein-glutaminase on structure and functional properties of alpha-zein. Yong, Y.H., Yamaguchi, S. & Matsamura, Y. (2006) Effects of enzymatic deamidation by protein-glutaminase on structure and functional properties of wheat gluten. J. Agric. Food Chem.54, 6034-6040 showed that water-insoluble gluten was able to be deamidated up to 72% in 30 hours and resulted in increase in solubility and improvement of emulsification properties. It was suggested that allergenicity of deamidated gluten was decreased markedly as deamidation extent was increased.

US Patent No 7,008,653 discloses a method for deamidat ion of milk protein and a method for denaturation of milk protein by using a deamidating enzyme wherein the enzyme is that described in US Patent No 7,846,709. US Patent No 7,008,709 also discloses that said enzyme has a deamidating effect on a protein having a molecular weight of 10,000 or more. Casein proteins were more readily deamidated than whey proteins. US Patent No 7,947,315 discloses a method for providing a dairy product smooth oral sensation and suppressed acidic taste and bitter taste and a method for manufacturing the same wherein a protein deamidating enzyme is added to raw milk to act on the milk protein in the raw milk.

US Patent Application No 20130236627 discloses coffee whiteners, prepared by using a casein-containing milk protein solution that has been deamidated with a protein deamidating enzyme, exhibiting excellent storage stability and dispersibility in coffee without the use of synthetic emulsifiers

OBJECT OF THE INVENTION

It is an object of the present invention to provide products obtained by novel transformations of the gluten complex into ingredient materials having minimum flavour and bland colour properties that display different physical and functional properties from the parent gluten complex which enable said transformed materials to be utilised advantageously as functional ingredients in a wide variety of minimally flavoured food applications.

SUMMARY OF THE INVENTION

Accordingly said invention discloses A method of producing an ingredient material for use in a food product, said method including the steps of transforming a parent gluten complex by two or more enzymatic processes whereby said ingredient material displays different physical and functional properties to said parent gluten complex.

In another aspect said invention further discloses a food product which includes an ingredient material produced by the above method.

Preferably additional physical or chemical treatments may be included to further modify the functional properties of the product.

In one of the processes the gluten complex is preferably fragmented by enzymatic hydrolysis to an extent determined by the application for the product; in the second process the interactive surface of the gluten fragments is preferably changed by enzymatic hydrolysis of a proportion of the glutamine constituent of the peptides and converting it to glutamic acid to an extent determined by the application for the product.

In a further preferred form of the invention products are disclosed resulting from additional transformation of the said transformed gluten fragments by additional physical and chemical processes that may further modify said transformed gluten fragments for advantageous outcomes.

In a furt her preferred form of the invention products are disclosed resulting from additional transformation of the said transformed gluten fragments by additional physical and chemical processes that may be applied between sequential application of the two enzymatic processes that may further modify said transformed gluten fragments for advantageous outcomes. More specifically, gluten fragments otherwise referred to as gluten-derived peptides or gluten peptides may be separated according to size or charge or may be separated according to solubility or may be separated according to another physical or chemical property of the gluten peptides

In a further preferred form of the invention products are disclosed resulting from modification of the parent gluten complex by physical and/or chemical processes prior to transformation of the said modified gluten complex by means of the aforesaid enzymatic processes.

In a further preferred form of the invention a process is disclosed that includes the transformation of gluten by at least two enzymatic processes occurring concurrently or sequentially. In one of the processes the gluten complex is fragmented by enzymatic hydrolysis to an extent determined by the application for the product ; in the second process the interactive surface of the gluten fragments is changed by enzymatic hydrolysis of a proportion of the glutamine constituent of the fragments and converting it to glutamic acid to an extent determined by the application for the product.

In a further preferred form of the invention a process is disclosed that additional transformation of the said transformed gluten fragments by additional physical and chemical processes that may further modify said transformed gluten fragments for advantageous outcomes according to the application for the product.

In a further preferred fonn of the invention products are disclosed resulting from additional preparative processes applied to the said transformed gluten fragments by physical means following the two enzymatic processes that may realise advantageous outcomes. More specifically, transformed gluten fragments otherwise referred to as transformed gluten-derived peptides or transformed gluten peptides may be separated according to size or charge or may be separated according to solubility or may be separated according to another physical or chemical property of the transformed gluten peptides and may be dried by any suitable means.

In a further preferred fonn of the invention it is disclosed that products constituted by and containing said novel transformed gluten fragments are utilised as ingredients in food systems providing unique and novel physical and chemical properties. Said food systems may include but not limited to:

novel foods arising from a dough or batter in which the elasticity, extensibility viscosity or other functional property importantly described for such food systems is enhanced;

novel manufactured meat products or meat analogue products in which the inclusion of water and fat components is enhanced

novel liquid foods and beverages in which the inclusion of water and fat components is enhanced

novel manufactured non-dairy fat powder and non-dairy creamer food products

Non-limiting examples of the invention that identify novel products, novel processes and applications for said novel products are as follows:-

Example 1 Enzymatic proteolysis of vital wheat gluten followed by separation of soluble from insoluble peptides followed by enzymatic deamidation of soluble peptides

A commercial tryptic-like enzyme of fungal origin was dispersed in warm water (60°C) in an amount being by weight 0.5% of the weight of dried vital wheat gluten to be processed. The dry vital wheat gluten was added with vigorous stirring such that the final content of gluten in the dispersion was 30% with the pH maintained between 5.8 and 6.2. After 1.5 hours when the amount of protein as enzyme-hydrolysed peptides had reached 70%, the suspension was heated to 90°C and held at that temperature for at least 1 minute to deactivate the proteolytic enzyme and prevent any further fragmentation or development of bitter flavour. After cooling to 60°C the suspension was centrifuged at 2000 x g for 3 minutes and the almost clear supernatant separated from the insoluble sedimented material.

The solubilised peptides in the supernatant were then treated with protein-deamidase enzyme (PG 50, Amano Enzymes) at 50°C with enzyme being dosed at 0.5% by weight of solubilised gluten peptides maintained at pH between 5.8 and 6.2 for 5 hours. The solution was heated to 80°C to inactivate the deamidase enzyme and cooled to 50°C, Dried product was obtained by spray drying the treated solution directly.

Dried solubilised and deamidated product was analysed for protein content, moisture, and ash content using standard methods of analysis. Extent of deamidation was estimated from release of ammonia and confirmed by amino acid analysis after complete enzymatic hydrolysis of the peptides.

Concentration of peptides in supernatant = 22% Extent of solubilisation of gluten = 73%

Analysis by size-exclusion HPLC of fragmentation of gluten and molecular weight distribution of soluble wheat peptides arising .

A 1 % w/w solution of solubilised wheat peptides in the supernatant as aforesaid was applied to a size exclusion HPLC column system constituted by 2 x TSK-3000 columns in series and eluted with water. Eluting peptides were detected and quantified using a UV-detector system. The HPLC column system was calibrated with standard reference proteins of known molecular weight and used to estimate molecular weights eluting as a function of elution volume. Figure 1 shows an HPLC chromatogram obtained by this procedure and in Table 1 is shown the estimation of peptide molecular weights represented by the peaks shown on the HPLC chromatogram (Figure 1 ) calculated relative to a calibration curve constructed using data from the elution of standard proteins of known molecular weight. Computation of area under each peak provides an estimation of the quantity of each peak. Relative quantities of peptides in sequential size distribution bands are shown in Table 2.

Table 1 Estimation of molecular weight distribution of soluble wheat peptides by HPLC analysis

Ammonia release and extent of deamidation determined by Kjeldahl method

Progress of deamidation by protein deamidase was determined by sampling the aforesaid reaction mixture at intervals, stopping further deamidation by heat inactivating the enzyme as aforesaid and measuring the quantity of free ammonia arisen from the deamidation reaction by a standard Kjeldahl method. Table 3 shows the extent of ammonia released during the progress of the reaction.

Total potential deamidation was estimated by acid hydrolysis of the sample in 0.1M sulphuric acid at 95°C for 30 minutes followed by measurement of the amount of ammonia released. Comparison of amount of enzyme-released ammonia to total potential provided an estimate of extent of deamidation as shown also in Table 3.

Table 3 Estimation of extent of deamidation of soluble wheat peptides

Extent of deamidation determined by amino acid analysis

Confirmation of the extent of deamidation was achieved by amino acid analysis of the untreated peptide preparation and the protein deamidase-treated preparation and comparison of the sum of glutamic acid and aspartic acid content with the sum of glutamine and asparagine contents in each preparation. Results of amino acid analyses are shown in Table 4

Table 4. Amino acid analysis of deamidated soluble wheat peptides and deamidated soluble wheat peptides after total enzymatic hydrolysis

Example 2. Enzymatic proteolysis of vital wheat gluten followed by separation of soluble from insoluble peptides followed by enzymatic deamidation of insoluble peptides

A commercial tryptic-like enzyme of fungal origin was dispersed in warm water (60°C) in an amount being by weight 0.5% of the weight of dried vital wheat gluten to be processed. The dry vital wheat gluten was added with vigorous stirring such that the final content of gluten in the dispersion was 30% with the pH maintained between 5.8 and 6.2. After 1.5 hours when the amount of protein as enzyme-hydrolysed peptides had reached 70%, the suspension was heated to 90°C and held at that temperature for at least 1 minute to deactivate the proteolytic enzyme and prevent any further fragmentation or development of bitter flavour. After cooling to 60°C the suspension was centrifuged at 2000 x g for 3 minutes and the almost clear supernatant separated from the insoluble sedimented material.

The insoluble peptides in the sediment were dispersed as a 15% w/w suspension then treated with protein-deamidase enzyme (PG 50, Amano Enzymes) at 50°C with enzyme being dosed at 1.0% by weight of solubilised gluten peptides maintained at pH between 5.8 and 6.2 for 8 hours. The solution was heated to 80°C to inactivate the deamidase enzyme and cooled to 50°C. Dried product was obtained by spray drying the treated solution directly.

Dried insoluble peptide product and the corresponding deamidated product were analysed for protein content, moisture and ash content using standard methods of analysis. Extent of deamidation was estimated from release of ammonia and confirmed by amino acid analysis after complete enzymatic hydrolysis of the peptides.

Extent of solubilisation of gluten = 73%

Proportion of peptides as insoluble sediment = 27%

Ammonia release and extent of deamidation determined by Kjeldahl method

Progress of deamidation by protein deamidase was determined by sampling the aforesaid reaction mixture at intervals, stopping further deamidation by heat inactivating the enzyme as aforesaid and measuring the quantity of free ammonia arisen from the deamidation reaction by a standard Kjeldahl method as in Example 1.

The total amount of amide-nitrogen in the original insoluble peptide sample was estimated by acid hydrolysis of the sample in 0.1 M sulphuric acid at 95°C for 30 minutes followed by measurement of the amount of ammonia released. Comparison of amount of enzyme-released ammonia to total potential provided an estimate of extent of deamidation as shown also in Table 5.

Table 5 Estimation of extent of deamidation of insoluble wheat peptides 0 0

60 3.7

90 8.2

120 10.9

180 14.6

240 17.3

300 20.2

360 21.7

420 23.0

500 24.5

Extent of deamidation determined by amino acid analysis

Confirmation of the extent of deamidation was achieved by amino acid analysis of the untreated peptide preparation and the protein deamidase-treated preparation and comparison of the sum of glutamic acid and aspartic acid content with the sum of glutamine and asparagine contents in each preparation.

Example 3. Soluble wheat peptides deamidated with protein deamidase show enhanced emulsification capacity

Emulsification capacity of deamidated soluble wheat peptides was measured according to a well-established procedure and compared to the emulsification capacity of non-deamidated soluble wheat peptides and sodium caseinate, a proteinaceous substance used widely in food emulsion systems owing to its excellent performance.

Method

A deamidated soluble wheat peptide sample ( extent of deamidation 30%), a non- deamidated soluble wheat peptide sample or sodium caseinate was dispersed in water at 50°C at a concentration of 0.4%) w/w. The pH was adjusted to be in the range 7.0 to 7.2 by addition of dilute sodium hydroxide solution and stirred until fully dissolved. Into a lOOOmL tall-form beaker, 125 mL of the test solution was placed and mixed vigorously with a Silverson homogeniser. Into this, vegetable oil ( yellow in colour) was added in a continuous stream, the quantity of oil being added was continuously monitored gravimetrically. With continuous addition of oil the mix became creamy white in colour and progressively more viscous as the oil-in-water emulsion being formed included more oil. When the emulsification capacity of the sodium caseinate, deamidated soluble wheat peptides or non-deamidated soluble wheat peptides was exceeded, the emulsion transformed instantaneously into a water-in-oil emulsion recognised by the sudden change in viscosity and colour change to yellow. At this point the quantity of oil added was noted and used to calculate the Emulsification Capacity (EC) expressed as weight of oil emulsified by lg emulsifier.

Results

Table 6 Emulsion capacities of deamidated soluble wheat peptides, non-deamidated soluble wheat peptides and sodium caseinate

Emulsification capacity of deamidated soluble wheat peptides was demonstrated in a coffee creamer emulsified food system according to an established procedure and compared to the emulsification capacity of non-deamidated soluble wheat peptides and sodium caseinate, a proteinaceous substance used widely in such food emulsion systems owing to its excellent performance.

Method

Coffee creamer products were made with a deamidated soluble wheat peptide sample, a non-deamidated soluble wheat peptide sample or sodium caseinate as the emulsifier.

Formulation

Glucose syrup (80% solids) 246g

Copha hydrogenated vegetable fat l OOg

Emulsifier 13g

Disodium hydrogen phosphate 6.5g

Water at 50°C 134g Disodium hydrogen phosphate was dissolved in the hot water. The emulsifier was added and dispersed fully using a Silverson homogeniser operating at 30% power. Glucose syrup was added and dispersed. The Copha hydrogenated fat was melted at 50°C and slowly added while continuously homogenising the mix. When all the ingredients were incorporated the homogenising power was increased to 100% and continued for a further 2 minutes when the product appeared uniform.

Evaluation of coffee creamer emulsion product

Emulsion stability was evaluated by centrifugation of each of the coffee creamer emulsions. 45g of each emulsion was dispensed into a 50mL capacity centrifuge tube and centrifuged on an Heraeus benchtop centrifuge in a series of increasing centrifugal severity. The centrifugation conditions and results are shown in Table 7.

Table 7 Emulsion stability of coffee creamer emulsions evaluated by a centrifugation test

Whereas the coffee creamer emulsions formulated with sodium casemate or deamidated soluble wheat peptides maintained visually homogenous emulsions at all levels of centrifugal severity employed, coffee creamer formulated with non- deamidated soluble wheat peptides began to destabilise under the mildest centrifugal conditions tested.

Emulsion stability of each of the coffee creamer emulsions was evaluated in a standard coffee whitening test Method

Black coffee was prepared by adding 5g of instant coffee granules into 200g boiling water. When uniformly dissolved 5g of each of the coffee creamer emulsions was added with gentle stirr ing into separate volumes of black coffee.

Results

Samples were evaluated visually over a period of time after standing with no further stirring or heating.

Observations are provided in Table 8.

Table 8. Performance of coffee creamers emulsified with either deamidated soluble wheat peptides, non-deamidated soluble wheat peptides or sodium caseinate.

Whereas the coffee creamer emulsions formulated with sodium caseinate or deamidated soluble wheat peptides whitened black coffee solution satisfactorily, coffee creamer formulated with non-deamidated soluble wheat peptides destabilised immediately on addition to the hot coffee. All whitened coffee samples showed some degree of destabilisation over 17 hours , the degree being very apparent as the coffee cooled and the floating free fat solidified as a scum layer. However, the extent of scum layer was very much greater in the sample containing non-deamidated soluble wheat peptides as emulsifier relative to the extents in samples formulated with sodium caseinate or deamidated soluble wheat peptides.

Example 4 Insoluble wheat peptides deamidated with protein deamidase transformed into hydrated and gellable substance

Hydration of insoluble wheat peptides The progress of deamidation of insoluble wheat peptides was shown in Example 2 , Table 5. At intervals during the deamidation of insoluble wheat peptides samples were withdrawn from the reaction mix and centrifuged to estimate possible change in volume and appearance of insoluble material. Using graduated conical centrifuge tubes the volume of sediment was read off directly and compared to that observed from before reaction commenced.

Results and observations are shown in Table 9. In the early stages of deamidation reaction, the insoluble peptides apparently hydrated and expanded and a proportion became dissolved or dispersed and were identified in the supernatant after

centrifugation by solids measurement and appearance. During the later stages of the reaction no further expansion of the pellet was observed but further amounts of solids appeared in the supernatant layer after centrifugation and a layer of lipid was noted on the top of the liquid in the centrifuge tube.

Table 9 . Volume of sediment and appearance of s upernatant recorded during deamidation of insoluble wheat peptides

Gelation of deamidated insoluble wheat peptides

Gelation of polymeric carbohydrates and proteins may induced by heating such materials in aqueous solution or by adding cross-linking agents according to well- established methods.. Both processes are deemed to bring about the formation of a highly hydrated interwoven matrix of extended polymeric structures that entraps water and forms a quasi-solid recognised as a gel.

Deamidated insoluble wheat peptides recovered after extensive deamidation ( 27%) as aforesaid ( Table 10) were either heated in the aqueous dispersion to 95°C for 15 min then cooled to ambient temperature, or exposed to the sulphydryl oxidising and cross- linking agent , dithiothreitol (0.5%) at 50°C or to both treatments, that is, after addition of dithiothreitol, the sample containing deamidated insoluble wheat peptides was heated at 95C for 15 min and then cooled to ambient temperature. The same procedures were applied to non-deamidated insoluble wheat peptides

Results are described in Table 10 (a) and (b)

Table 10 Gelation of deamidated insoluble wheat peptides

(a) treatments applied to deamidated insoluble wheat peptides

Figure 1 Chromatogram showing HPLC analysis of soluble wheat peptides - results for 3 x samples overlaid.

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It will thus be appreciated that this invention at least in the forms of the examples described provides novel products derived from wheat gluten that can be used advantageously as food ingredients in a range of foods additional to traditional uses for gluten as in bakery goods, pasta and noodles. Additionally, processes are disclosed for making the aforesaid novel products and applications for such novel products in foods. The examples disclosed however are only the currently preferred forms of the invention and additional modifications may be made within the scope of the invention as defined by the following claims.