阅读说明：本技术 一种液态乳的杀菌方法 (Liquid milk sterilization method ) 是由 王婧宇 龄南 王猛 胡长利 崇志文 杨若茜 杨姚远 于 2020-06-05 设计创作，主要内容包括：本发明提供了一种液态乳的杀菌方法,属于食品加工技术领域。本发明采用抑菌剂乳酸链球菌素对液态乳进行抑菌后再进行超高压水射流杀菌处理,解决了单独使用乳酸链球菌素保质期短的问题,且超高压水射流技术不仅有杀菌作用又有均质的作用,可以进一步促进乳酸链球菌素的溶解,达到均匀化分布的目的,使其抑菌作用得到最大发挥。本发明的方法不仅避免了使用超高温瞬时灭菌对液态乳品质造成较大破坏,又解决了温和杀菌方式(例如巴氏杀菌)对应的保质期短的问题,能够延长牛奶的低温保质期至143d,同时牛奶的风味、色泽和味道较好。(The invention provides a sterilization method of liquid milk, and belongs to the technical field of food processing. The invention adopts the bacteriostatic agent nisin to carry out the ultra-high pressure water jet sterilization treatment after the liquid milk is bacteriostatic, solves the problem of short shelf life of the nisin which is used independently, and the ultra-high pressure water jet technology has the sterilization effect and the homogenization effect, can further promote the dissolution of the nisin, achieves the aim of uniform distribution and exerts the bacteriostatic effect to the maximum. The method of the invention not only avoids great damage to the quality of the liquid milk caused by using ultrahigh temperature instantaneous sterilization, but also solves the problem of short shelf life corresponding to a mild sterilization mode (such as pasteurization), can prolong the low-temperature shelf life of the milk to 143 days, and simultaneously has good flavor, color and taste of the milk.)

1. A method for sterilizing liquid milk, comprising the steps of:

1) adding nisin into liquid milk to obtain mixed milk, and homogenizing the mixed milk to obtain homogenized milk; the addition amount of nisin in the mixed milk is 0.1-0.5 g/L;

2) carrying out ultrahigh pressure water jet sterilization on the homogeneous milk to obtain sterilized milk; the pressure of the ultrahigh-pressure water jet sterilization is 50-350 MPa.

2. The sterilization method according to claim 1, wherein the liquid milk comprises cow's milk.

3. The sterilization method according to claim 1, wherein the nisin is added in step 1) in a manner comprising: firstly, dissolving nisin in partial liquid milk to obtain a solution containing nisin, and then adding the solution into the residual liquid milk.

4. The sterilization method according to claim 1, wherein the pressure for the homogenization in step 1) is 150 to 220bar and the temperature is 25 to 30 ℃.

5. The sterilization method according to claim 1, wherein the sample injection temperature of the ultra-high pressure water jet sterilization sample in the step 2) is 4 ± 2 ℃.

6. The sterilization method as claimed in claim 1, wherein the nozzles used in the ultra-high pressure water jet sterilization in step 2) are coaxial and equal-quantity colliding nozzles.

7. The sterilization method according to claim 1, wherein the sterilized milk in step 2) is collected in a container resistant to ultra-high pressure and subjected to sterilization treatment, and is cooled to 2-6 ℃ for storage.

Technical Field

The invention relates to the technical field of food processing, in particular to a sterilization method of liquid milk.

Background

Commercially available liquid milk products (except yoghurt) mainly comprise pasteurized fresh milk and UHT sterilized normal-temperature milk, and the products are mainly classified according to different milk production processes, wherein the pasteurized fresh milk sterilization process is pasteurization (72 ℃ for 15s), and the normal-temperature milk sterilization process is ultrahigh-temperature instant sterilization (135 ℃ to 150 ℃ for 4s to 15 s).

Wherein, pasteurization is a mild heat treatment mode, which can kill yeast, mould and most bacteria (including pathogenic bacteria) in the milk, but can not kill thermophilic bacteria and spores thereof. Therefore, the pasteurized milk needs to be stored at the temperature of about 4 ℃, the shelf life is about 3-10 days, and the shelf life is very short.

The ultrahigh-temperature instantaneous sterilization method is characterized in that milk is subjected to instantaneous sterilization treatment of ultrahigh-temperature instantaneous sterilization to completely destroy microorganisms and spores capable of growing in the milk, and then the milk is subjected to aseptic packaging and filling to obtain a finished product. Because the process completely kills the risk microorganisms, the shelf life of the product can be greatly prolonged under the condition of normal-temperature storage, but the decomposition of heat-sensitive components and the loss of volatile components are easily caused by high temperature, so that the loss of nutrient substances is large, and the sensory quality of the product is influenced.

Therefore, a method which can effectively prolong the shelf life and ensure the sensory quality of the liquid milk is lacked at present.

Disclosure of Invention

The invention aims to provide a liquid milk sterilization method, which can prolong the shelf life of liquid milk and ensure the sensory quality of the liquid milk.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a sterilization method of liquid milk, which comprises the following steps:

1) adding nisin into liquid milk to obtain mixed milk, and homogenizing the mixed milk to obtain homogenized milk; the addition amount of nisin in the mixed milk is 0.1-0.5 g/L;

2) carrying out ultrahigh pressure water jet sterilization on the homogeneous milk to obtain sterilized milk; the pressure of the ultrahigh-pressure water jet sterilization is 50-350 MPa.

Preferably, the liquid milk comprises cow's milk.

Preferably, the addition manner of nisin in step 1) comprises: firstly, dissolving nisin in partial liquid milk to obtain a solution containing nisin, and then adding the solution into the residual liquid milk.

Preferably, the homogenizing pressure in the step 1) is 150-220 bar, and the temperature is 25-30 ℃.

Preferably, in the step 2), the sample injection temperature of the ultrahigh-pressure water jet sterilization sample is 4 +/-2 ℃.

Preferably, the nozzles used for the ultrahigh-pressure water jet sterilization in the step 2) are coaxial and equivalent impinging nozzles.

Preferably, the sterilized milk in the step 2) is collected by using a container which is resistant to ultrahigh pressure and subjected to sterilization treatment, and is cooled to 2-6 ℃ for storage.

The invention has the beneficial effects that: the invention adopts the bacteriostatic agent nisin to carry out the ultra-high pressure water jet sterilization treatment after the liquid milk is bacteriostatic, solves the problem of short shelf life of the nisin which is used independently, and the ultra-high pressure water jet technology has the sterilization effect and the homogenization effect, can further promote the dissolution of the nisin, achieves the aim of uniform distribution and exerts the bacteriostatic effect to the maximum. The method of the invention not only avoids great damage to the quality of the liquid milk caused by using ultrahigh temperature instantaneous sterilization, but also solves the problem of short shelf life corresponding to a mild sterilization mode (such as pasteurization), can prolong the low-temperature shelf life of the milk to 143 days, and simultaneously has good flavor, color and taste of the milk.

Detailed Description

The invention provides a sterilization method of liquid milk, which comprises the following steps:

1) adding nisin into liquid milk to obtain mixed milk, and homogenizing the mixed milk to obtain homogenized milk; the addition amount of nisin in the mixed milk is 0.1-0.5 g/L;

2) carrying out ultrahigh pressure water jet sterilization on the homogeneous milk to obtain sterilized milk; the pressure of the ultrahigh-pressure water jet sterilization is 50-350 MPa.

Firstly, adding nisin into liquid milk to obtain mixed milk, and homogenizing the mixed milk to obtain homogenized milk; the addition amount of nisin in the mixed milk is 0.1-0.5 g/L, preferably 0.2-0.3 g/L, and the antibacterial effect is best within the addition amount range of 0.1-0.5 g/L.

In the present invention, the liquid milk preferably includes cow's milk; the cow milk is preferably from a guard house self-nutrition ecological ranch and meets the requirements of GB 19301-.

In the present invention, the addition mode of nisin preferably comprises: firstly, dissolving nisin in partial liquid milk to obtain a solution containing nisin, and then adding the solution into the residual liquid milk; the ratio of nisin to part of liquid milk is not particularly limited in the present invention, based on the fact that nisin can be sufficiently dissolved.

In the invention, the nisin belongs to food-grade bacteriostatic substances; the nisin has the functions of better antisepsis and bacteriostasis, weakening the heat treatment intensity, reducing the processing cost and improving the flavor, appearance and nutritive value of milk; the nisin is commercially available from conventional sources, and in the practice of the present invention is commercially available from Asahi Biotech, Inc. in Anhui.

In the invention, the homogenizing pressure is preferably 150-220 bar, and more preferably 180-200 bar; the temperature is preferably 25-30 ℃, more preferably 28 ℃, and the adopted equipment is preferably a high-pressure homogenizer which is purchased from Shanghai Shenlu homogenizer Co., Ltd; the homogenization serves to stabilize the fat emulsion against gravity separation.

After the homogenized milk is obtained, carrying out ultrahigh pressure water jet sterilization on the homogenized milk to obtain sterilized milk; the pressure of the ultrahigh-pressure water jet sterilization is preferably 100-300 MPa, more preferably 150-250 MPa, and most preferably 200 MPa; the sample injection temperature of the sample is 4 +/-2 ℃; the equipment used is preferably ultra-high pressure water jet equipment available from Nanjing Dada Water jet Co. In the invention, the sterilization effect is good within the pressure range of 50-350 MPa.

In the invention, the nozzle used for ultrahigh pressure water jet sterilization is preferably a coaxial and equivalent colliding nozzle; the coaxial and equal-quantity colliding nozzles are adopted because the sterilizing effect of the colliding nozzles in the two kinds of nozzles of the ultrahigh-pressure water jet equipment is better than that of the colliding nozzles under the same conditions.

The invention combines homogenization and ultrahigh pressure water jet sterilization, and can stabilize the quality of milk.

The nisin is used for homogenization treatment and then subjected to ultrahigh pressure water jet sterilization, so that on one hand, the ultrahigh pressure water jet sterilization solves the problem that the nisin has weak sterilization effect under the independent action, and on the other hand, the ultrahigh pressure water jet sterilization has a homogenization effect, the nisin is further promoted to be dissolved, and the effect is exerted to the maximum extent.

Collecting sterilized milk by using a container which is resistant to ultrahigh pressure and subjected to sterilization treatment. After the sterilized milk is obtained, cooling the sterilized milk to 2-6 ℃, preferably 4 ℃, and refrigerating; the collection container is preferably a high pressure resistant container, which is selected because the sterilized milk is sprayed at a speed of 1000m/s through a nozzle, resulting in a high pressure.

The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.