JPH029780B2 - - Google Patents

Description

[Detailed description of the invention]

A. Field of Industrial Application The present invention relates to the production of foods that are fermented using lactic acid bacteria and lactic acid bacteria and yeast. In the manufacturing process of foods that are fermented with lactic acid bacteria and yeast, by continuously measuring the electrical conductivity in the fermentation substrate,
The aim is to obtain fermented foods with constant acidity, pH, or texture. B. Prior art and its problems There are many foods that are fermented using lactic acid bacteria and/or yeast. Examples include fermented milk (yoghurt), lactic acid bacteria drinks, and sterilized concentrated lactic acid bacteria drinks such as Calpis.
There are milk liquors such as Kumis. The manufacturing methods for these products vary depending on the type and region, and cannot be discussed uniformly, but the following manufacturing processes are generally known. Dairy products such as skim milk powder and concentrated milk are added to milk and skim milk for reinforcement, or dairy products such as milk powder, concentrated milk, cream, etc. are reduced as the main raw material, and as necessary, Fruit juice, sugar, gelling agent, etc. are used as auxiliary raw materials and mixed together. This material is homogenized and sterilized according to conventional methods, and heated to 40 to 45℃.
After cooling, Lactobacillus bulgaricus, Streptococcus, Streptococcus
mixed starter of Lactobacillus thermophilus or Lactobacillus jugurti
It is produced by inoculating 2 to 3% of a single starter and carrying out lactic acid fermentation. In the case of kefir, kefyr, etc., which use yeast, they are produced by simultaneously inoculating lactic acid bacteria with Candida kefyr, etc., and carrying out lactic acid fermentation and alcohol fermentation using yeast bacteria. Fermentation is usually stopped by cooling the substrate being cultured for fermentation or by heating and sterilizing it, but the determination of when to stop fermentation is made by measuring the acidity of lactic acid or the pH. However, there are many drawbacks to determining when fermentation has stopped using these measurements. To determine lactic acid acidity and determine when fermentation has stopped, a portion of the fermented substrate is sampled and the lactic acid acidity is measured. However, if sampling is done at the wrong time, fermentation may proceed too much and the acidity may drop. This can lead to a higher level of alcohol content, resulting in a product that is too vinegary and has a strong alcohol odor, which can impair its quality. Furthermore, measuring lactic acid acidity by titration is time-consuming. When measuring PH and determining when fermentation has stopped, attaching the electrode of the PH meter to the fermented substrate and continuously monitoring the PH changes will prevent errors in determining when fermentation has stopped. Due to its structure, PH electrodes are unsuitable as food manufacturing equipment because the internal liquid of the electrode (containing silver chloride or mercury) leaks into the substrate, albeit in a small amount. C. Means for solving the problems In order to solve these problems, the inventor focused on the phenomenon that during the metabolic growth process of microorganisms, the amount of electrolyte in the culture medium increases and the conductance increases. . Conductivity measurement allows continuous control of the fermentation of the substrate in the same way as PH measurement, and there is no phenomenon such as leakage of the internal liquid of the electrode into the fermentation substrate as in PH measurement. It's a method. When measuring electrical conductivity, there are roughly two methods. One method uses a metal as the detection end, and the metal itself directly contacts the fermentation substrate to measure the conductivity. This method uses electromagnetic induction to measure the conductivity of the fermentation substrate from the induced current flowing between the transformers when the substrate is brought into contact with the transformer. Generally, when the conductivity in the substrate is small, the former method is used, and when the conductivity is large, the latter method is used, but in either case, the conductivity in the fermentation substrate is still measured. . D. Effect When milk or other raw materials are used as the main raw material, sterilized according to conventional methods, inoculated with lactic acid bacteria and/or yeast, and fermented, the sugars in the substrate are decomposed by the lactic acid bacteria, resulting in organic acids, carbon dioxide, alcohol, etc. Changes to. This change results in an increase in the amount of electrolyte, leading to an increase in electrical conductivity. If you calculate the correlation between the lactic acid acidity, PH, sugar consumption, flavor, and conductivity in advance, you will not make a mistake in determining when to stop fermentation. A description will be given below based on specific examples. Example: Raw milk was homogenized at 150Kg/ ^cm2 in the usual manner, and heated to 120℃.
The mixture was heat sterilized for 2 seconds, cooled, and kept at 43°C to serve as a fermentation substrate (base). To this, add a 3.0% (V/
V) After inoculating and stirring uniformly, the mixture was kept at 43°C and fermented. At this time, a conductivity meter was installed inside the fermentation tank, and changes in conductivity during the fermentation process as well as changes in lactic acid acidity, PH, and temperature were measured. The results are shown in Table 1, which is illustrated in FIG.

[Table] During fermentation, the fermentation was stopped by rapid cooling when the conductivity reached 10,500 μS/cm. At this time, lactic acid acidity is 0.8
%, and the flavor was also good. Effects By measuring the electrical conductivity continuously in this way, there was no error in the measurement when the fermentation was stopped, and it was more hygienic and simpler than the conventional method.

[Brief explanation of drawings]

Figure 1 shows the electrical conductivity, lactic acid acidity, and
This shows changes in pH and temperature. −〇−……Conductivity −●−……Lactic acid acidity −△−……PH −▲−……Temperature

Claims (1)

[Claims] 1. In the process of fermentation using lactic acid bacteria and/or yeast on a substrate prepared by adding fruit juice, sucrose, gelling agent, etc. to a dairy raw material such as milk or skim milk, the electrical conductivity (conductance) in the substrate is determined. A food fermentation management method that allows you to know when fermentation has stopped by continuously measuring changes in .