Liquid oat base

Abstract

A process for preparing a liquid oat base or drink of improved soluble oat protein content from an oats material, in particular an oats material that has not been heat treated in a humid state, comprises solubilizing oat protein in an aqueous solvent by means of protein-deamidase. Also disclosed is a corresponding liquid oat base and uses thereof.

Claims

1. A process for preparing a liquid oat base or drink of improved soluble oat protein content from an oats material comprising starch and oat protein, optionally enriched with at least one member selected from the group consisting of vegetable oil, sodium chloride, dicalcium phosphate, tricalcium phosphate, calcium carbonate, and vitamin, comprising: providing the oats material, including the starch and the oat protein of the oats material, in an aqueous medium, degrading the starch of the oats material with at least one amylase, and solubilizing the oat protein of the oats material using protein-deamidase without use of protease, and wherein the protein-deamidase is glutaminase, wherein the amount of protein glutaminase used in the process is from 0.5 U/g of oat protein to 2 U/g of oat protein, wherein the amylase comprises β-amylase, and wherein the process is conducted to obtain a content of soluble protein from 10 per cent by weight and up to 20 per cent by weight, and wherein the oat protein solubilization and starch degradation is carried out at a temperature of from 50° C. to 60° C., and wherein the oats material is at least one member selected from the group consisting of non-steamed wet milled oats, non-steamed dry milled oats, non-steamed oat bran, and non-steamed dehulled or hulless/naked dry milled oat flour, and wherein the oat protein is solubilized by protein-deamidase concurrently with two steps of starch degradation, and wherein the beta amylase is added in an amount sufficient for the hydrolysis of at least 50% of the starch over a time period of from 0.5 hours to 4 hours.

2. The process for preparing a liquid oat base as a food, a food additive or a starting material for the production of food, for human consumption which comprises using the liquid oat base of claim 1 as said food, food additive or starting material.

3. The process of claim 1, further comprising UHT treating the resulting product.

4. The process of claim 1, wherein said two steps are separated by a period extending from 30 min to 90 minutes.

Description

DESCRIPTION OF PREFERRED EMBODIMENTS

(1) Material and Methods

(2) Oat kernels: Dehulled, steam treated, wet ground or dry ground.

(3) Oat bran (Frebaco Kvarn A B, LidköPing, Sweden): 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.

(4) Enzymes: Protein-glutaminase “Amano 50”, 50 U/g (Amano Inc., Japan). Commercial alpha-amylase and beta-amylase are available from various commercial sources.

(5) Alpha-amylase activity: 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

(6) Beta-amylase activity: One BNPβ-G3 (p-nitrophenyl-β-D-maltotrioside) unit is defined as the amount of enzyme required to release one micromole of p-nitrophenol from PNPβ-G3 in one minute under defined assay conditions: http://secure.megazyme.com/files/BOOKLET/K-BETA3_1010_DATA.pdf

(7) Protein-glutaminase activity: One activity unit (U) is defined as the quantity of enzyme producing one μmol of ammonia per min in the reaction with 10 mM aqueous benzylocarbonyl-L-glutaminylglycine (Cbz-Gln-Gly).

(8) Viscosity: Measured with a Brookfield Visco DV-II+ instrument (http://www.brookfieldengineering.com/products/viscosimeters/laboratory-dv-ii.asp.

EXAMPLE 1

Pilot Scale Process for Producing the Improved Oat Base of the Invention

(9) Dehulled, steam treated oat kernels (675 kg) were wet ground in a colloidal mill at a temperature of 54° C. and directly fed into a stainless steel enzyme treatment tank over a period of about 20 min. Stirring was started at a mash volume of about 100 L. About 7.5 L of an aqueous solution of alpha-and beta-amylase (1 Ceralpha unit per 180 Betamyl-3 units per g of starch) was used. Enzyme activity may vary depending on the commercial source of the enzymes; the total weight of amylases in this experiment was 432 g. The enzyme solution was fed into the tank in parallel with the mash over a period of about 12 min at the end of which about 3000 L of the mash had been fed into the tank. The rest of the mash was fed into the tank over a period of about 8 min to bring the total contents of the tank to about 5600 L. The temperature of the mash was kept constant at 56° C.

(10) Protein-glutaminase (PG) dosing. PG (687.5 g) was dissolved in 1.5 L water at room temperature. The PG solution was added to the mash at a viscosity of 160.5 (sp2/60 rpm/25±2° C.). Stirring was continued for about 120 min at a temperature of about 56° C. to reach a mash viscosity of 35 (sp2/60 rpm/25±2° C.) and a pH of 6.6. Any enzyme activity was then destroyed by heating the product to 95° C. The mash was cooled to room temperature and decanted. Decantation can be omitted if a whole grain product is to be produced.

(11) The thus produced oat base of the invention can be transferred into a formulation tank in which rapeseed oil, vitamins, sodium chloride, di- and tricalcium phosphate, and calcium carbonate is added. The thus obtained enriched oat drink has a viscosity (sp2/60 rpm/25±2° C.) of 17.5 cP and a pH of 6.8. The formulated oat drink or oat milk is transferred to a storage tank from which it is dispensed for UHT treatment and packaging.

(12) Product analysis. Deamidation of product: 7.3% of total releaseable ammonia (by treatment with 2 N sulphuric acid at 100° C. for 4 h). Deamidation of control (non-enzymatic deamidation): 1.6% of total releaseable ammonia (same process in absence of PG). Soluble protein: 78% of total protein (product of the invention) v. 64% of total protein (control).

(13) Instead of dehulled steam treated oat kernels also corresponding naked kernels may be used, for instance, as a starting material.

EXAMPLE 2

Modified and Down-scaled (1:105) Process of Example 1

(14) Wet-milled oat slurry is heated to 60° C. under stirring. Alpha-and beta-amylase as well as protein glutaminase (1 U/g of oat protein) are added and reacted with the slurry under stirring at 60° C. for two hours. The slurry is the heated to 95° C. for 5 min. Insoluble matter is removed by pulse centrifugation (pulses of 1100 g) and analyzed.

(15) Product analysis. Deamidation of product: 6.9% of total releaseable ammonia. Deamidation of control (non-enzymatic deamidation): 1.9% of total releaseable ammonia (same process in absence of PG). Soluble protein: 84% of total protein (product of the invention) v. 56% of total protein (control).

EXAMPLE 3

Modified and Down-scaled Process of Example 1

(16) The process of Example 2 was repeated but with heat treated dry milled and sieved oat kernels, fraction size <0.5 mm mixed with water to a dry weight of 11%.

(17) Product analysis. Deamidation of product: 6.1% of total releaseable ammonia. Deamidation of control (non-enzymatic deamidation): 1.5% of total releaseable ammonia (same process in absence of PG). Soluble protein: 59% of total protein (product of the invention) v. 48% of total protein (control).

EXAMPLE 4

Modified and Down-scaled Process of Example 1

(18) The process of Example 2 was repeated but with non-heat treated dry milled and sieved oat kernels, fraction size <0.5 mm mixed with water to a dry weight of 11%.

(19) Product analysis. Deamidation of product: 8.9% of total releaseable ammonia. Deamidation of control (non-enzymatic deamidation): 1.5% of total releaseable ammonia (same process in absence of PG). Soluble protein: 81% of total protein (product of the invention) v. 62% of total protein (control).

EXAMPLE 5

Deamidation of Oat Drink at Laboratory and Pilot Plant Scale by Protein-glutaminase

(20) The oat base or drink used in this example was prepared according to the method disclosed in European patent no. 731 646. This oat drink is a commercial product manufactured by Oatly AB, Landskrona, Sweden. In Table 1 important features of a number of products according to the invention are shown. Also shown are corresponding features of deamidation products obtained from dry-milled heat-treated oats. The products were obtained in absence of deamidase (0 U) and in presence of deamidase at two deamidase addition regimes (1 U; 2×0.5 U/g oat protein). It is evident from Table 1 that the content of total protein is substantially increased in the presence of deamidase. It is also evident that, at otherwise identical conditions, a non-heat treated starting material yields a product with higher protein content than a corresponding heat-treated starting material.

(21) It is furthermore evident that that, at otherwise identical conditions, sequential addition of deamidase (2×0.5 U) yields a product of higher protein content than obtained by a single addition of the same amount of amylase (1 U). A higher protein content of the product is paralleled by increased emulsion stability (reduced sedimentation rate) of the product.

(22) TABLE-US-00001 TABLE 1 Deamidation of oat drink at laboratory and pilot plant scale Protein-Glutaminase, Soluble protein, Total Droplet Oat raw U/g of Deamidation g/100 g (% of protein size (μm), material Oat Protein (%) total) g/100 g 1.5% fat Sedimentation Laboratory scale Wet-milled 0 U 1.9 0.71 (57%) 0.84 3.2 14% UPH** 1 U 6.7 0.90 (72%) 0.92 1.7 2 white PH* 2 × 0.5 U*** 6.9 1.06 (87%) 0.95 0.8 2 white PH Dry-milled, 0 U 1.5 0.59 (46%) 0.64 4.5 17% UPH heat treated 1 U 6.1 0.75 (59%) 0.81 3.6 No sediment 2 × 0.5 U*** 8.6 0.80 (63%) 0.80 4.0 No sediment Dry milled, 0 U 1.5 0.88 (64%) 0.80 2.6 38% UPH non-heat 1 U 8.9 1.16 (81%) 0.92 1.2 30% UPH treated 2 × 0.5 U*** 9.5 1.26 (93%) 0.94 1.2 28% UPH Oat bran 0 U 1.8 0.41 (17%) 1.25 7.1 13% UPH 1 U 5.9 1.05 (42%) 1.62 6.3 7% UPH 2 × 0.5 U*** 6.1 1.09 (44%) 1.60 5.6 4% UPH Small pilot scale Wet-milled 0 U 2.3 0.65 (56%) 0.82 15.8 10% UPH 1 U 7.9 0.70 (67%) 0.80 15.8 2 white PH 2 × 0.5 U*** 13.0 0.83 (72%) 1.01 17.8 No sediment Large pilot scale Wet-milled 0 U 1.6 0.70 (64%) 0.75 7.9 63% UPH 2 × 0.5 U*** 7.3 1.00 (78%) 0.91 10.0 2 white PH *PH = Phase; **UPH = Upper phase; ***0.5 U added to each of two amylase enzymation steps