The late nineties of last century, as China Juice Industrial development, especially in the growing export fruit juice concentrates, fruit juice international market for China’s increasingly stringent quality requirements, continue to set the technical barriers, the juice is one of thermo-acidophilic bacteria. Initially, the juice business, research Detector Structure of such a lack of understanding of microbial contamination is difficult to control in production on its. The next few years, we have adopted to strengthen and foreign, foreign research institutions to communicate, bonding juice production process, these microorganisms in the juice of the fruit quality will be the source of what impact, how to detect, control of such microorganisms and other issues in-depth study and exploration to help enterprises improve production of many fruit juice processing conditions, to products that thermo-acidophilic bacteria has been well controlled. Currently, most concentrated fruit juice products company has been able to meet the requirements of foreign investors on this indicator, in order to enable us to better understand and solve the thermo-acidophilic bacteria in juice of technical problems, we consider it necessary to acidophilic the characteristics of heat-resistant bacteria, measurement and process control and other work to sum up, in order to further common understanding, improve product quality.
1, thermo-acidophilic bacteria of the types and characteristics
Concentrated fruit juice generally have a lower pH, water activity is low, the characteristics of higher sugar content in fruit juice processing and concentration process to go through heating, so the vast majority of micro-organisms can not survive, and only a few bacteria, mold and yeast can survive in the fruit juice concentrate. Thermo-acidophilic bacteria is that a small number of bacteria in a class. PH value in the lower, the thermo-acidophilic bacteria can form spores with heat resistance, juice pasteurization commonly used in hard to kill. Its spores survive in dormant form: in the concentrated fruit juice, when the fruit juice after rewatering, suitable conditions will Bacillus germination, growth, resulting in loss of juice products aroma, taste variation, turbidity increased, the formation of precipitation. It is noteworthy that there is thermo-acidophilic bacteria does not necessarily make the product bad, not spoiled fruit juice can be detected in bacteria, deterioration occurs only under appropriate conditions, will generally lead to loss of fruit flavor and a slight haze.
1984, there were researchers from the pasteurized apple juice after the corruption identified as an acidophilus bacteria, the strain can be 26 ~ 55 temperature range pH2.6 ~ 6.0 under the conditions of growth, and its spores with strong resistance to heat, at lower pH value, the industry after pasteurization can still survive. 1992, the researchers classified the type of thermo-acidophilic bacteria in a new genus: genus.AlicydobacJllus. Currently, the genus is known mainly three kinds: Bacillusacidocaldarius, Bacillusacidoterrestris and Bacilluscycloheptanicus.
Alicyclobacillus species of bacteria are strict acidophilic bacteria, their growth pH range of 2.0 to 6.0, growth temperature range of 40 ~ 70 , which are aerobic or facultative anaerobic bacteria, when the adverse environmental and nutritional conditions to the formation of endogenous spores.
Alicyclobacillusacedocaldarius as aerobic gram-positive bacteria, can form spores in dust, long 2 ~ 3m, width 0.7 ~ 0.8rrm, 5 ~ 6 cells formed short chains. The kinds of bacteria sporangia not expanding, less heat tolerance. The kinds of bacteria growth pH range of 2.0 to 6.0, optimum growth temperature was 45 ~ 70 , without growth factor. The species of bacteria colony flat, irregular margin, does not produce pigment. The main sources of bacteria to the thermal environment.
Alicyclobacitlusacidoterrestfis as aerobic gram-positive bacteria, can form spores in dust, long 2.9 ~ 4.3pm, width 0.6 ~ 0.8rrm, endogenous spore is oval. The kinds of bacteria do not need growth factors, growth temperature range of 35 ~ 55 , optimum temperature of 42 ~ 53 , the growth pH can range from 2.2 to 5.8, 5% sodium chloride can not grow under the conditions. The kind of vaccine off the round, yellow-white, opaque or translucent.