# US 10,368,558 B2 · Lactase solution and dairy product using same

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- Number: US 10,368,558 B2
- Document ID: US10368558B2
- Status: Granted
- Kind: B2
- Application number: 15/532,633
- Filed: 2015-11-20
- Published: 2017-12-28
- Granted: 2019-08-06
- Earliest claimed: 2014-12-05
- Assignees: Godo Shusei Co., Ltd.
- Applicants: Godo Shusei Co., Ltd.
- Inventors: Tomoko Sato; Jun Yoshikawa; Hirofumi Horiguchi
- Web page: https://patentgrep.com/patent/US10368558B2

## CPC

- A23C 7/04: Removing unwanted substances {other than lactose or milk proteins} from milk
- A23C 9/12: Fermented milk preparations; Treatment using microorganisms or enzymes
- A23C 9/1206: {Lactose hydrolysing enzymes, e.g. lactase, beta-galactosidase}
- C12N 1/02: Separating microorganisms from their culture media
- C12N 9/2468: {acting on beta-galactose-glycoside bonds, e.g. carrageenases (3.2.1.83; 3.2.1.157); beta-agarase (3.2.1.81)}
- C12Y 302/01108: Lactase (3.2.1.108)
- G01N 27/44747: {Composition of gel or of carrier mixture}
- A23C: DAIRY PRODUCTS, e.g. MILK, BUTTER OR CHEESE; MILK OR CHEESE SUBSTITUTES; PREPARATION THEREOF (preservation thereof A23B11/00)
- C12N: MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA (microbiological testing media C12Q1/00)
- C12Y: ENZYMES
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

[Problem] To provide a lactase solution having excellent thermal stability. [Solution] A lactase solution in which the ratio of a lactase fraction having a molecular weight of about 120 kDa measured by SDS polyacrylamide gel electrophoresis is 20% or more.

## Claims

### Claim 1

A lactase solution comprising a lactase derived from a yeast of the genus Kluyveromyces, the lactase solution comprising a lactase fraction having a molecular weight of about 120 kDa measured by SDS polyacrylamide gel electrophoresis in a ratio of 20% or more,
wherein the sum of the ratio of the about 120 kDa lactase fraction and a ratio of a lactase fraction having a molecular weight of about 80 kDa measured by SDS polyacrylamide gel electrophoresis is 100%.

### Claim 2 (depends on 1)

The lactase solution according to claim 1, wherein a ratio of a lactase fraction having a molecular weight of about 50 kDa measured by SDS polyacrylamide gel electrophoresis is 70% or less.

### Claim 3 (depends on 2)

A dairy product comprising the lactase solution according to claim 2.

### Claim 4 (depends on 2)

A method for treating a raw material milk, comprising adding to a raw material milk the lactase solution according to claim 2, and decomposing lactose contained in the raw material milk at 1 to 49° C.

### Claim 5 (depends on 1)

The lactase solution according to claim 1, wherein a value obtained by dividing the sum of the ratio of the about 120-kDa lactase fraction and the ratio of the about 80-kDa lactase fraction by the ratio of the lactase fraction having the molecular weight of about 50 kDa measured by SDS polyacrylamide gel electrophoresis is 0.5 or more.

### Claim 6 (depends on 5)

A dairy product comprising the lactase solution according to claim 5.

### Claim 7 (depends on 5)

A method for treating a raw material milk, comprising adding to a raw material milk the lactase solution according to claim 5, and decomposing lactose contained in the raw material milk at 1 to 49° C.

### Claim 8 (depends on 1)

A dairy product comprising the lactase solution according to claim 1.

### Claim 9 (depends on 1)

A method for treating a raw material milk, comprising adding to a raw material milk the lactase solution according to claim 1, and decomposing lactose contained in the raw material milk at 1 to 60° C.

### Claim 10 (depends on 1)

The lactase solution according to claim 1, further comprising a stabilizer.

### Claim 11 (depends on 10)

The lactase solution according to claim 10, wherein the stabilizer is glycerin.

### Claim 12 (depends on 1)

A method for producing the lactase solution claim 1, comprising
culturing a microorganism producing a lactase as an intracellular enzyme,
collecting the lactase from the culture product obtained in the culturing, wherein the collecting comprises extracting the lactase from the microorganism, and
purifying the collected lactase, wherein the purifying includes performing one or more cycles of a step-comprising a salting-out treatment and a desalting treatment.

### Claim 13 (depends on 12)

The method for producing the lactase solution according to claim 12, wherein the salting-out treatment comprises:
adding, to the collected lactase, a salting-out agent to a degree of saturation of 10 to 90%; and
allowing, after the adding, the lactase to stand at a temperature of 4 to 40° C. for a period of 1 to 80 hours.

### Claim 14 (depends on 13)

The method for producing the lactase solution according to claim 13, wherein the salting-out treatment is carried out at pH 4 to 9.

### Claim 15 (depends on 12)

The method for producing the lactase solution according to claim 12, wherein the salting-out treatment is carried out at pH 4 to 9.

### Claim 16 (depends on 12)

The method according to claim 12, wherein the lactase is a lactase derived from a yeast of the genus Kluyveromyces.

### Claim 17 (depends on 12)

The method according to claim 12, wherein the lactase has an optimum pH ranging from 6 to 8.