USE OF LACTASE TO PROVIDE HIGH GOS FIBER LEVEL AND LOW LACTOSE LEVEL
A method for providing a low lactose milk-based product having GOS fiber is provided in which a milk substrate having lactose is treated with a transgalactosylating enzyme to provide GOS fiber and remaining lactose; deactivating the transgalactosylating enzyme; contacting the milk-based substrate having GOS fiber with a lactase to degrade the remaining lactose to provide the low lactose milk-based product having GOS fiber and deactivating the lactase. Also provided are enzymes and GOS fiber and lactose amounts and stability.
1 . A method for preparing a low lactose milk-based product having GOS fiber, the method comprising the steps of providing a milk-based substrate comprising lactose;
treating said milk-based substrate with a transgalactosylating enzyme to provide GOS fiber and remaining lactose;
deactivating the transgalactosylating enzyme;
contacting the milk-based substrate having GOS fiber with a lactase to degrade the remaining lactose to provide the low lactose milk-based product having GOS fiber; and
deactivating the lactase.
2 . The method of claim 1 wherein the milk-based substrate has a lactose concentration of between 1-60% (w/w); or 2-50% (w/w), or 3-40% (w/w); or 4-30% (w/w).
3 . The method of claim 1 wherein the transgalactosylating enzyme is a truncated β-galactosidase from Bifidobacterium bifidum.
4 . The method of claim 3 wherein the truncated β-galactosidase from Bifidobacterium bifidum is truncated on the C-terminus.
5 . The method of claim 4 wherein the truncated β-galactosidase from Bifidobacterium bifidum comprises a polypeptide having at least 70% sequence identity to SEQ ID. NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4 or SEQ ID NO:5 or to a transgalactosylase active fragment thereof.
6 . The method of claim 5 wherein the polypeptide has at least 80% sequence identity to SEQ ID. NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4 or SEQ ID NO:5 or to a transgalactosylase active fragment thereof.
7 . The method of claim 6 wherein the polypeptide has at least 90% sequence identity to SEQ ID. NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4 or SEQ ID NO:5 or to a transgalactosylase active fragment thereof.
8 . The method of claim 7 wherein the polypeptide has at least 95% sequence identity to SEQ ID. NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4 or SEQ ID NO:5 or to a transgalactosylase active fragment thereof.
9 . The method of claim 8 wherein the polypeptide has at least 99% sequence identity to SEQ ID. NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4 or SEQ ID NO:5 or to a transgalactosylase active fragment thereof.
10 . The method of claim 9 wherein the polypeptide comprises a sequence according to SEQ ID. NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4 or SEQ ID NO:5 or to a transgalactosylase active fragment thereof.
11 . The method of claim 10 wherein the polypeptide comprises a sequence according to SEQ ID. NO:1 or to a transgalactosylase active fragment thereof.
12 . The method of claim 11 wherein the polypeptide comprises a sequence according to SEQ ID. NO:1.
13 . The method of claim 1 wherein the deactivation of the transgalactosylating enzyme comprises heat treatment.
14 . The method of claim 13 wherein heat treatmentis from about 70° C. to 95° C. and for between about 5 minutes to 30 minutes.
15 . The method of claim 14 wherein the heat treatment is at about 95° C. for 5 to 30 minutes.
16 . The method of claim 13 wherein the heat treatment is from about 135° C. to about 150° C. for about 2 seconds to about 15 seconds.
17 . The method of claim 1 wherein the lactase is a K. lactis lactase.
18 . The method according to claim 17 wherein the K. lactis lactase comprises a polypeptide having at least 80% sequence identity to SEQ ID. NO. 6 or to a lactase active fragment thereof.
19 . The method according to claim 18 wherein the K. lactis lactase comprises a polypeptide having at least 90% sequence identity to SEQ ID. NO. 6 or to a lactase active fragment thereof.
20 . The method according to claim 19 wherein the K. lactis lactase comprises a polypeptide having at least 95% sequence identity to SEQ ID. NO. 6 or to a lactase active fragment thereof.
21 . The method according to claim 20 wherein the K. lactis lactase comprises a polypeptide having at least 99% sequence identity to SEQ ID. NO. 6 or to a lactase active fragment thereof.
22 . The method according to claim 21 wherein the K. lactis lactase comprises a polypeptide according to SEQ ID. NO. 6 or to a lactase active fragment thereof.
23 . The method according to claim 22 wherein the K. lactis lactase comprises a polypeptide according to SEQ ID. NO. 6.
24 . The method of of claim 1 wherein less than 20% of the GOS fiber is hydrolyzed by the lactase during the step of contacting the milk-based substrate having GOS fiber with said lactase.
25 . The method of claim 24 wherein less than about 15% of the GOS fiber is hydrolyzed.
26 . The method of claim 25 wherein less than about 10% of the GOS fiber is hydrolyzed.
27 . The method of claim 26 wherein less than about 5% of the GOS fiber is hydrolyzed.
28 . The method of claim 1 wherein the deactivation of the lactase enzyme comprises heat treatment.
29 . The method according to 28 wherein the heat treatment is at about 135° C. to about 150° C. for about 2 to about 15 seconds, about 85° C. to about 115° C. for about 0.5 to about 9 seconds or at about 70° C. to about 85° C. for about 15 seconds to about 30 seconds.
30 . The method claim 1 wherein the deactivating step of the lactase comprises reduction of the pH of the milk-based substrate having GOS fiber and the lactase.
31 . The method according to claim 30 wherein reduction of the pH is accomplished by adding yogurt or cheese cultures to the milk-based substrate.
32 . The method of claim 1 wherein the low lactose milk-based product having GOS fiber is yoghurt, ice cream, UHT milk, flavored milk product, concentrated/condensed milk product, milk-based powder, or cheese.
34 . The method of claim 1 wherein the GOS fiber in the low lactose milk-based product is stable having a variance of less than about 10% within 28 days.
35 . The method of claim 1 wherein the low lactose milk-based product having GOS fiber contains more than about 1.5% (w/w) GOS fiber.
36 . The method according to claim 35 wherein the low lactose milk-based product having GOS fiber contains more than about 3.2% (w/w) GOS fiber.
37 . The method according to claim 36 wherein the low lactose milk-based product having GOS fiber contains more than about 4% (w/w) GOS fiber.
38 . The method according to claim 37 wherein the low lactose milk-based product having GOS fiber contains more than about 7% (w/w) GOS fiber.
39 . The method according to claim 38 wherein the low lactose milk-based product having GOS fiber contains more than about 14% (w/w) GOS fiber.
40 . The method according to claim 39 wherein the low lactose milk-based product having GOS fiber contains more than about 30% (w/w) GOS fiber.
42 . The method of claim 1 wherein the low lactose milk-based product having GOS fiber contains more than 1.5 g GOS fiber per 100 kcal and below 0.1% lactose or below 0.01% lactose.
43 . The method of claim 1 wherein the lactose in the milk-based substrate has been reduced more than about 50%, more than about 97%, more than about 98%, more than about 99% or more than about 99.7%.
44 . The method of claim 1 further comprising the steps of dehydrating the low lactose milk-based product to provide a powder and dissolving the powder in water.