| Alicyclobacillus acidoterrestris,also named TAB, is one kind of New polluted bacteria in syrup.It was reported repeatedly on foreign journal. Many kind of syrup such as cider, orange juice, grape juice and ade can be polluted by TAB.TAB has strong heat-resistant characteristic. It can survive in acid syrup used pasteurisation treatment.It can also lead the good sense quality of syrup to badness even its concentration bally low. But at present there is no mature and reliable technology to control TAB in syrup. Therefore it is urgent to solve the problem that how to effectively control TAB in syrup.Nisin is a kind of savageness biology antiseptic and has the special characteristic of safe, high effect and savageness. A majority of bacteria of gram-positive,especially thermotolerant bacillus coagulans such as burgeoning Clostridium botulinum can be inhibited by Nisin .It establish theory foundation by there characters for applying nisin to antisepsis and sterilization of syrup. The study and application of nisin focus on recently a few years. Komitopoulou and Yamazaki et al study the inhibition of nisin on TAB spore in cider, orange juice and grape juice and get delightful result. The study of TAB in our country was relatively late and mainly focused on concentrated apple juice. It is very few reports about the separateness of TAB from orange juice, the inhibition of nisin to TAB and applications of nisin in syrup. In the article, based on separateness of TAB from orange juice, the study is entire and systemic on the physiological and growing character of separated bacteria, the inhibition of nisin on TAB in orange juice. Some effective measures and approaches were obtained from the study and offer theory foundation and technology parameter, the study result are as following:1 Study on the growth character of TAB in orange juice1.1 It was successful to separated one bacteria strain similar with standard TAB bacteria from reechy orange juice.1.2 The best growth conditions for separated TAB strains is:402 culture medium, growth pH is 3.7,cultured temperature is 45 °C.1.3 It was proved by identifying the character of bacteria strains and thalli ,the biochemistry character of bacteria strains that the separated bacteria strains is TAB bacteria strains1.4 TAB bacteria strains on 45±1°C grow faster than normal temperature. TAB bacteria strains grow slow on low temperature in orange juice.1.5 On 80±l°C,the D value of TAB was 38.31 min when pH value of orange juice is 3.8 and the D value of TAB was 4.25min on 95±1'C. It had great effect on heat-resistant character of TAB spore by temperature, heat-resistant character of TAB spore was obviously drop with temperature increasing. TAB bacterial strains spore had strong heat-resistant character under different temperature and can survive after UHT.1.6 Heat-resistant character of TAB spore was effected by pH value, on 8O±l°C,the D value of TAB was 42.37 min when pH value of orange juice is 4.3 and the D value was 35.84 min upon pH value 3.0.Compared with pH 3.0, heat-resistant character of TAB spore was stronger upon pH 4.3.It was proved that the lower ph value and the higher temperature orange juice was, the better effect it was got on heat-resistant character of TAB spore.2 Study on inhibition of Nisin to growth of TAB in orange juice2.1 On acid condition, the antibacterial effect of Nisin liquor gradually worse, nisin still is active after treatment of 115*C and 121 °C. the antibacterial effect of Nisin strengthen with pH value decrease, when pH value was more than 4, the antibacterial effect of Nisin with pH value increasing, the combination of pH value and temperature strengthen the antibacterial effect of Nisin. the higher the concentration of nisin is, the better result it can get. 500mg/kg nisin liquor can completely control 6.1xl04cfu/ml TAB bacteria strains.2.2 When put nisin into orange juice, heat-resistant character of TAB bacteria strains obviously dropped. The higher the temperature was, the more sensitivity and antibacterial TAB bacteria strains were when they were appeared upon heat after be treated with nisin. It reduced sterilized temperature and cut the heat treatment time if nisin was put into orange juice.2.3 There was great effect by temperature on minimum inhibiting concentration of nisin on TAB in orange juice, on 25 "C, minimum inhibiting concentration of nisin on TAB bacterial strains in orange juice was 25mg/kg. And it was 80mg/kg when on 45*C.Compared with nutritional body of TAB, TAB spore was more sensitivity when treated with nisin. 80mg/kg nisin liquor can completely control 2.4xl02cfu/ml TAB bacteria strains. |
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