阅读说明：本技术 一种牛奶中革兰氏阴性致病菌的杀菌方法 (Method for sterilizing gram-negative pathogenic bacteria in milk ) 是由 肖性龙 曹怡芳 余以刚 于 2019-11-15 设计创作，主要内容包括：本发明涉及食品杀菌技术,具体公开了一种牛奶中革兰氏阴性致病菌的杀菌方法,包括以下步骤：在牛奶中加入香芹酚和柠檬醛,再对牛奶辅以加热处理,加热温度为40-55℃,直至致病菌被全部杀灭,停止加热,得到无菌牛奶。本发明将植物源化合物与温和加热处理联合,协同杀菌,能对牛奶中常见的革兰氏阴性致病菌达到理想的杀菌效果；且比巴氏杀菌处理温度低,杀菌时间短。同时还能够最大程度保持牛奶中原有的营养价值和风味。(The invention relates to a food sterilization technology, and particularly discloses a method for sterilizing gram-negative pathogenic bacteria in milk, which comprises the following steps: adding carvacrol and citral into milk, heating the milk at 40-55 deg.C until pathogenic bacteria are completely killed, and stopping heating to obtain sterile milk. According to the invention, the plant source compound is combined with mild heating treatment, and sterilization is performed cooperatively, so that an ideal sterilization effect on common gram-negative pathogenic bacteria in milk can be achieved; and has lower temperature and shorter sterilization time than pasteurization treatment. Meanwhile, the original nutritional value and flavor of the milk can be maintained to the maximum extent.)

1. A method for sterilizing gram-negative pathogenic bacteria in milk is characterized by comprising the following steps:

adding carvacrol and citral into milk, heating the milk at 40-55 deg.C until pathogenic bacteria are completely killed, and stopping heating to obtain sterile milk; when the heating temperature is more than or equal to 40 and T is less than 45 ℃, the concentration of carvacrol in the milk is more than or equal to 200 mu g/mL, and the concentration of citral is more than or equal to 1600 mu g/mL; when the heating temperature is more than or equal to 45 ℃ and T is less than 50 ℃, the concentration of carvacrol in the milk is more than or equal to 100 mu g/mL, and the concentration of citral is more than or equal to 800 mu g/mL; when the heating temperature T is not less than 50 ℃ and not more than 55 ℃, the concentration of carvacrol in the milk is not less than 50 mug/mL, and the concentration of citral is not less than 400 mug/mL.

2. The sterilization method as claimed in claim 1, wherein when the heating temperature T is more than or equal to 45 ℃ and less than 50 ℃, the concentration of carvacrol in the milk is more than or equal to 200 μ g/mL, and the concentration of citral is more than or equal to 1600 μ g/mL; when the heating temperature T is not less than 50 ℃ and not more than 55 ℃, the concentration of carvacrol in the milk is not less than 100 mu g/mL, and the concentration of citral is not less than 800 mu g/mL.

3. The sterilization method according to claim 1 or 2, wherein the heating time is 5 to 90 min.

4. The sterilization method according to claim 3, wherein the heating time is 10 to 30 min.

5. The sterilization method according to claim 4, wherein the heating temperature T is 50 ℃ or more and 55 ℃ or less, and the heating time is 15 +/-5 min.

Technical Field

The invention relates to a sterilization technology in food, in particular to a sterilization method of gram-negative pathogenic bacteria in milk.

Background

Milk is one of the oldest natural beverages and is rich in proteins, fats, vitamins and minerals. The milk is rich in nutrition, easy to digest and absorb, high in quality, low in price and convenient to eat, and is a main food of human daily diet. However, milk is also susceptible to the growth of various microorganisms, particularly some gram-negative pathogenic bacteria: escherichia coli, Salmonella, Cronobacter sakazakii, and the like. Therefore, it is very important to control the pathogenic bacteria in milk. Is commonly used for sterilizing milkThe method is a traditional pasteurization method and mainly comprises three steps: low temperature long time sterilization (63 deg.C, 30min), high temperature short time sterilization (72 deg.C, 15s), and ultra high temperature instantaneous sterilization (138 deg.C, 2-4 s). The sterilization methods can kill most harmful pathogenic bacteria in the milk, but can cause adverse effects to different degrees on nutrient substances, texture and flavor in the milk; and the equipment required for pasteurization is expensive, and needs to be cleaned and monitored in time, so that the cost is high. In recent years, non-thermal sterilization techniques have been used for inactivation of food-borne pathogenic bacteria in milk, such as high-voltage pulsed electric field, ultra-high voltage, ultrasonic waves and SC-CO₂The technologies can achieve good antibacterial effect under the optimal conditions, but the sub-lethal damage to cells is caused after the treatment of the ultrahigh-voltage and high-voltage pulse electric field, and potential harm is caused in the subsequent storage process of the milk; the sterilization effect of the ultrasonic wave is influenced by more factors, and whether the ultrasonic wave can be applied to the dairy industry needs further verification; SC-CO₂The equipment is expensive and the operation is complex, so the popularization in the dairy industry is difficult.

Recently, there has been a trend towards the use of plant-derived compounds for bacteriostasis, which are considered to be non-toxic and harmless, and many of which have been approved for use as food additives. However, when the plant source compound is used alone, the ideal bacteriostatic effect can be achieved only at a high bacteriostatic concentration, so that the food flavor is also adversely affected.

Disclosure of Invention

The invention aims to provide a method for sterilizing gram-negative pathogenic bacteria in milk. The method of the invention applies the plant source compound with synergistic bactericidal effect, and then is assisted with medium-low temperature heating treatment for a period of time, so that all bacteria in the milk can be killed, and the original nutritional quality and flavor of the milk can be maintained. The invention can replace or partially replace pasteurization more effectively.

The object of the invention is achieved by the following steps:

a method for killing gram-negative pathogenic bacteria in milk comprises the following steps:

adding carvacrol and citral into milk, heating the milk at 40-55 deg.C until pathogenic bacteria are completely killed, and stopping heating to obtain sterile milk; when the heating temperature is more than or equal to 40 and T is less than 45 ℃, the concentration of carvacrol in the milk is more than or equal to 200 mu g/mL, and the concentration of citral is more than or equal to 1600 mu g/mL; when the heating temperature is more than or equal to 45 ℃ and T is less than 50 ℃, the concentration of carvacrol in the milk is more than or equal to 100 mu g/mL, and the concentration of citral is more than or equal to 800 mu g/mL; when the heating temperature T is not less than 50 ℃ and not more than 55 ℃, the concentration of carvacrol in the milk is not less than 50 mug/mL, and the concentration of citral is not less than 400 mug/mL.

Preferably, when the heating temperature T is more than or equal to 45 ℃ and less than 50 ℃, the concentration of carvacrol in the milk is more than or equal to 200 mu g/mL, and the concentration of citral is more than or equal to 1600 mu g/mL; when the heating temperature T is not less than 50 ℃ and not more than 55 ℃, the concentration of carvacrol in the milk is not less than 100 mu g/mL, and the concentration of citral is not less than 800 mu g/mL.

Preferably, the heating time is 5-90 min.

Preferably, the heating time is 10-30 min.

Preferably, the heating temperature is more than or equal to 50 and less than or equal to 55 ℃, and the heating time is 15 +/-5 min.

The concentration of the plant source compound is the final concentration of the plant source compound added into a milk system.

Compared with the existing pasteurization technology, the invention has the following advantages and technical effects:

(1) according to the invention, the plant source compound is combined with mild heating treatment, so that a synergistic sterilization effect can be achieved; and has lower temperature and shorter sterilization time than pasteurization treatment.

(2) Simple use, low cost and high cost-effectiveness ratio.

(3) The plant source compound is natural, nontoxic, and edible, and can be used as food additive.

(4) The ideal sterilization effect is achieved, and meanwhile, the original nutrition, texture and flavor of the milk can be kept to the maximum extent.

Drawings

FIG. 1 shows the bacteriostatic effect of carvacrol and citral at different concentrations in example 3 on E.coli in milk at different heating temperatures, A, B, C, D representing heating temperatures of 40, 45, 50 and 55 deg.C, respectively.

Fig. 2 is the bacteriostatic effect of carvacrol and citral at different concentrations in example 4 on salmonella in milk at different heating temperatures, A, B, C, D representing heating temperatures of 40, 45, 50 and 55 ℃ respectively.

Fig. 3 is the bacteriostatic effect of carvacrol and citral at different concentrations in example 5 on cronobacter sakazakii in milk at different heating temperatures, A, B, C, D representing heating temperatures of 40, 45, 50 and 55 ℃ respectively.

FIG. 4 shows the inactivation effect of the optimal sterilization conditions on the mixed bacteria liquid of different gram-negative pathogenic bacteria in milk in example 6 of the present invention.

Detailed Description

To further describe the present invention, the present invention will be described in further detail with reference to examples. The reagents and methods used in the present invention are, unless otherwise specified, those commonly used in the art and conventional methods.