ENHANCED VISCOSITY OAT BASE AND FERMENTED OAT BASE PRODUCT

Abstract

A process for producing a non-dairy food product of enhanced viscosity comprises providing a mixture of deamidated oat base and vegetable protein isolate, crosslinking of glutamine and lysine units of the protein isolate and oat protein comprised by the oat base by means of transglutaminase, and fermenting the mixture by means of a yogurt, sour cream or cheese starter culture. Also disclosed are products obtainable by the process and their use.

Claims

1. Process for producing a non-dairy food product of enhanced viscosity, comprising providing a mixture of deamidated oat base and vegetable protein isolate; and crosslinking of glutamine and lysine units of the protein isolate by means of transglutaminase.

2. The process of claim 1, wherein the mixture is heated to a temperature of 80 C. or more prior to the addition of transglutaminase.

3. The process of claim 1, wherein the added vegetable protein isolate consists of or comprises denaturated vegetable protein.

4. The process of claim 3, wherein the vegetable protein isolate comprises or consists of pea protein isolate, potato protein isolate, faba bean protein isolate, chickpea protein isolate, lentil protein isolate, in particular consists of pea protein isolate.

5. The process of claim 1, comprising, prior to incubation with transglutaminase, adjusting and/or holding the mixture at a pH substantially higher than that of the isoelectric point of the vegetable protein isolate, such as higher by 1.0 pH units, in particular higher by 1.5 pH units or 2.0 pH units or more.

6. A process for producing oat base or oat drink of enhanced viscosity, comprising: a) Providing an oat base or drink optionally comprising a viscosity promoting agent; b) Providing native vegetable protein isolate and/or denaturated vegetable protein isolate; c) Combining the oat base or drink and vegetable protein isolate; d) Heating the combination of oat base and vegetable protein isolate to a temperature of 80 C. or higher and keeping it at this temperature for a time sufficient to form a combination of oat base or drink and heat-treated vegetable protein isolate; e) Bringing the combination of oat base or drink and heat-treated vegetable protein isolate to a temperature of from 35 C. to 65 C.; f) Adding a protein cross-linking amount of transglutaminase to the combination of oat base or drink and heat-treated vegetable protein isolate while keeping the mixture at said temperature of from 35 C. to 65 C. for a time required to increase viscosity by a factor of 2 or more, in particular of 5 or more to form a viscosity enhanced oat base; g) Inactivating transglutaminase by heating the viscosity enhanced oat base or drink to a temperature of 80 C. or more, in particular of 90 C. or more; and h) Cooling the viscosity enhanced oat base or drink to one of: room temperature or below if desired to be stored for a longer time or to a temperature suitable for further processing; with the proviso that protease activity is excluded from the process.

7. The process of claim 6, wherein the oat base or drink is a deamidated oat base or drink.

8. The process of claim 6, wherein the vegetable protein isolate is or comprises pea protein isolate.

9. The process of claim 6, wherein the pea protein isolate is or comprises denaturated pea protein isolate.

10. The process of claim 6, wherein the vegetable protein isolate is added in an amount so as to raise the total protein content of the oat base to 2% by weight or more, in particular to 3% by weight or more, most preferred to 4% or 5% by weight or more.

11. The process of claim 6, wherein the viscosity enhanced oat base or drink has a dry matter content of from 8 to 15% by weight, more preferred of from 9 to 12% by weight, most preferred of about 10% or 11% by weight.

12. The process of claim 11, wherein the viscosity enhanced oat base or drink dry matter comprises from 10% to 50% by weight of maltose or of a mixture of maltose and glucose, from 30% to 80% by weight of maltodextrin.

13. The process of claim 6, wherein the denaturation period is from 5 min to 60 min, in particular from 10 min to 30 min, and wherein the denaturation temperature is from 80 C. to 95 C.

14. The process of claim 6, wherein the viscosity enhanced oat base or drink has a viscosity of 2000 Pa-s or more in particular of 5000 Pa-s or more, and even of 10000 Pa-s or more.

15. The process of claim 6, wherein the viscosity enhanced oat base or drink has an elastic modulus of 100 Pa to 500 Pa or up to 1000 Pa or more.

16. The process of claim 6, wherein the viscosity enhanced oat base or drink has a yield point greater by factor of 1.5 or 2 more than the yield point of a corresponding non-enhanced oat base.

17. The process of claim 6, wherein the viscosity promoting agent is calcium carbonate.

18. The process of claim 6, comprising, prior to and/or during incubation with transglutaminase, adjusting and/or holding the mixture at a pH substantially higher than that of the isoelectric point of the vegetable protein isolate, such as higher by 1.0 pH units, in particular higher by 1.5 pH units or 2.0 pH units or more.

19. Oat base or drink of enhanced viscosity obtainable by a process according to claim 6.

20-34. (canceled)

Description

DESCRIPTION OF PREFERRED EMBODIMENTS

[0045] Material and Methods

[0046] Oat Kernels:

[0047] Dehulled, steam treated, wet ground or dry ground.

[0048] Oat Bran (Frebaco Kvarn AB, Lidkping, Sweden):

[0049] Prepared from steam treated Swedish oat grain by grinding in a rolling mill. Composition (% by weight): Protein 18, fat 7, carbohydrate 45, fiber 16%, water 9.5.

[0050] Enzymes:

[0051] Transglutaminase, alpha-amylase, beta-amylase as well as yogurt and fresh cheese products, such as sour cream, quark and cream cheese, are available from various commercial sources such as Danisco DuPont (Yomix, Denmark) and Christian Hansen (YoFlex, eXact; Denmark). Prior to use transglutaminase and yogurt culture were dissolved in tap water (15 U/g and 0.001-0.2 g/g, respectively).

[0052] Alpha-Amylase Activity:

[0053] One Ceralpha unit is defined as the amount of enzyme required to release one micromole of p-nitrophenol from BPNPG7 (non-reducing end blocked p-nitrophenyl maltoheptaoside) in one minute under defined assay conditions: http://secure.megazyme.com/files/BOOKLET/K-BETA3_1010_DATA.pdf

[0054] Beta-Amylase Activity:

[0055] One BNP-G3 (p-nitrophenyl--D-maltotrioside) unit is defined as the amount of enzyme required to release one micromole of p-nitrophenol from PNP-G3 in one minute under defined assay conditions: http://secure.megazyme.com/files/BOOKLET/K-BETA3_1010_DATA.pdf.

[0056] Transglutaminase Activity:

[0057] Determined by the hydroxamate method. One unit corresponds to the amount of enzyme generating 1 mol of hydroxamic acid per min at pH 6.0.

[0058] Viscosity:

[0059] Measured with Kinexus Pro+, Malvern Instruments, UK; http://www.malvern.com/en/producs/product-range/kinexus-range/kinexus-por-plus/.

Example 1. Process for Producing the Viscosity-Improved Oat Base of the Invention from a State-of-the Art Oat Base

[0060] Materials:

[0061] Oat base produced according to EP 1124441 A1 containing about 1% by weight of oat protein, to which rapeseed oil had been added to rise the total fat content to about 3% by weight; transglutaminase ACTIVA TG-WM (100 U/g), Ajinomoto (Japan); pea protein, Nutralys S85F and F85F containing about 80% by weight of protein (Roquette, France); YoMix 511 yogurt culture, Danisco DuPont (Denmark); rapeseed oil (AAK, Sweden); granulated sugar. Aqueous solutions were prepared for addition during fermentation: a) 15 U/g transglutaminase solution b) 1.8% by weight Yomix 511 solution.

[0062] Pea protein (3.8 g) was added to 94 g oat base in a glass flask and the mixture shaken to disperse the protein. The flask was immersed in a boiling water bath of 95 C. and kept at this temperature for 10 min, then cooled to room temperature by immersing it in cold water. The mixture was used as starting material.

[0063] First Variety of the Process of the Invention: Simultaneous Cross-Linking and Fermentation.

[0064] The following components were admixed with the starting material: 265 l transglutaminase solution (1 U/g protein); 340 l YoMix solution (0.0006%); 1.15 g rapeseed oil (to make total fat content about 4% by weight); 0.69 g of granulated sugar. The mixture was shaken to mix and dissolve the components, then kept in a water bath of 43 C. overnight. The reaction was quenched by bringing the reaction mixture to boiling in a microwave oven, followed by shaking and renewed heating so as to bring it to the boiling point. The mixture was cooled and stored in a refrigerator for analysis.

[0065] Second Variety of the Process of the Invention: Consecutive Cross-Linking and Fermentation.

[0066] Transglutaminase solution (265 l, 1 U/g protein) was added to the starting material (about 100 g). The mixture was stored for 3 h in a water bath of 50 C. and agitated once hourly. The reaction was quenched by bringing the reaction mixture to boiling in a microwave oven followed by shaking and renewed heating so as to bring it to the boiling point in the oven. The cooled product is a viscosity enhanced oat base or oat drink of the invention. It can be used as such as a food product or in the manufacture of food products or be fermented. If used for fermentation, the following agents were added to the cooled viscosity enhanced oat base or oat drink: 340 l YoMix solution (0.006%), 1.15 g rapeseed oil to make total fat content about 4% by weight); 0.69 g of granulated sugar (0.69% by weight); it is however within the ambit of the invention to add rapeseed oil and/or granulated sugar at an earlier stage of the process. The mixture was incubated overnight in a water bath of 43 C. The so produced non-dairy yogurt was cooled and kept in a refrigerator for analysis.

Example 2. Crosslinking Efficacy of Different Protein Isolates

[0067] A number of vegetable protein isolates were included to demonstrate their crosslinking properties at a total protein content of 4% by weight in deamidated oat base. The results were confirmed by rheology measurements, illustrated in Table 1 (consecutive crosslinking and fermentation) and Table 2 (simultaneous crosslinking and fermentation). Oat base without added protein isolate resulted in zero shear viscosity of about 50 Pa.Math.s, elastic modulus (G) of about 5 Pa and a yield point of about 1.

TABLE-US-00001 TABLE 1 Crosslinking effect of transglutaminase on fermented products of combinations of protein isolates and deamidated oat base, consecutive crosslinking and fermentation Protein isolate added to a Viscosity, Elastic modulus Yield content of 4% total protein Pa .Math. s Pa point Pea (Nutralys S85F) 2 000 300 0.9 Chickpea (FCPP40) 3 000 200 1.1 Pea (Pisane C9) in combination 8 000 800 1 with deamidated oat drink

TABLE-US-00002 TABLE 2 Crosslinking effect of transglutaminase on fermented products of combinations of protein isolates and deamidated oat base, simultaneous crosslinking and fermentation Protein isolate added to a Viscosity, Elastic modulus Yield content of 4% total protein Pa .Math. s Pa point Pea (Nutralys S85F) 6 000 800 1.9 Potato Solanic 200) 3 000 300 0.9 Faba bean (Vitessence 3600) 18 000 1 200 2.2 Lentil (Vitessence 2550) 2 000 300 1.4 Chickpea (FCPP40) 4 000 300 1.6 Pea (Pisane C9) in combination 40 000 5 000 2 with deamidated oat drink

Example 3. Crosslinking Efficacy of Different Starting Materials

[0068] An important factor for crosslinking properties is the nature of the protein isolate, as demonstrated in Example 2. Another important factor is whether a protein isolate had undergone a heat treatment prior to crosslinking, as illustrated in Table 3. The effect of heat treatment seems however not to be of a general nature but limited to certain protein isolates, for example pea protein isolate. According to the invention properties of the resulting gel or curd can be adjusted by varying time and/or temperature of heat treatment. Higher temperatures and/or longer periods of treatment result in increased viscosity and gel strength.

[0069] The inclusion of deamidated oat base or oat drink and addition of a viscosity promoting agent are additional factors affecting crosslinking properties and viscosity. The combination of oat base and pea protein that had not been heat-treated prior to transglutaminase incubation did not thicken, while heat treatment resulted in slightly increased viscosity.

TABLE-US-00003 TABLE 3 Crosslinking effect of transglutaminase on fermented products of heat-treated (10 min, 95 C.) and non-heat-treated combinations of protein isolates and deamidated oat drink, consecutive/simultaneous crosslinking and fermentation Elastic Viscosity, modulus, Yield Protein isolate Pa .Math. s Pa point Consecutive Pea (Nutralys S85F) Heated 2 000 200 1 Pea (Nutralys S85F) Non-heated 300 10 1 Potato (Solanic 200) Heated 5 000 1 800 1.5 Potato (Solanic 200) Non-heated 7 000 600 0.6 Simultaneous Pea (Nutralys S85F) Heated 17 000 800 1.6 Pea (Nutralys S85F) Non-heated 4 500 550 1.6 Potato (Solanic 200) Heated 1 000 1 700 1.1 Potato (Solanic 200) Non-heated 2 000 1 700 0.9

[0070] Application of the same treatment to the combination of deamidated oat drink and pea protein in absence of heat-treatment resulted in a somewhat thick gel while heat-treatment provided a strong gel or curd. The effects of deamidated oat drink were confirmed by rheology measurements, illustrated in Table 4. The inclusion of calcium carbonate (corresponding to a calcium content of about 120 mg/100 ml) as viscosity promoting agent to the oat base increased viscosity and provided an even stronger gel or curd.

TABLE-US-00004 TABLE 4 Crosslinking effect of transglutaminase on fermented products of combinations of pea protein isolate and oat drinks, consecutive/simultaneous crosslinking and fermentation Elastic Viscosity, modulus, Oat drink Pa .Math. s Pa Yield Consecutive Deamidated Heated 2 000 200 1 Non-heated 300 10 1 Non-deamidated Heated 600 90 1 Non-heated 40 1 0.9 Simultaneous Deamidated Heated 17 000 800 1.6 Non-heated 4 500 550 1.6 Non-deamidated Heated 5 500 500 1.4 Non-heated 150 10 1

Example 4

[0071] Adjusting/holding the pH to/at a pH substantially different from that of the isoelectric point during incubation with transglutaminase increased viscosity and provided a stronger gel or curd.

[0072] The isoelectric point of vegetable protein isolates is at about pH 4.5; for pea protein isolates is at about pH 4.4. Table 5 illustrates the increase in viscosity upon adjusting the pH of oat drink comprising pea protein isolate to pH 6.5 and 7.5 prior to incubation with transglutaminase and fermentation. Aqueous sodium hydroxide and hydrochloric acid were used for pH adjustment.

TABLE-US-00005 TABLE 5 Crosslinking effect of transglutaminase on fermented products with pH adjusted different from isoelectric point, consecutive crosslinking and fermentation. Elastic Viscosity, modulus, Yield Oat drink pH Pa .Math. s Pa point Deamidated 6.5 2 000 50 0.9 Deamidated 7.5 3 000 200 1 Non-deamidated 6.5 200 1 0.5 Non-deamidated 7.5 1 500 200 1