| Pickled radish is a kind of vegetable which is popular among Chinese residents.But the water content of Pickled radish is high,and the Pickled radish often contains rich nutrients.Therefore,the Pickled radish is easy to be contaminated by microorganisms.Most of the Pickled radishs on the market are added with chemical preservatives,and the phenomenon of excessive addition is more serious,there is a greater risk of food safety.Biological preservatives are a kind of preservatives developed rapidly in recent years.Their advantages are higher food safety and better preservative effect than chemical preservatives.However,the cost of biological preservatives is relatively high,so the use of biological preservatives in practical application is restricted.Several safe and efficient biological preservatives were used in this study,and their application in Pickled radish was studied.Firstly,five bacteria includinmg Bacillus subtilis,Bacillus thuringiensis,Bacillus megaterium,Bacillus aerophilus and Bacillus pumilus,and 3 fungi including Fusarium oxysporum,Penicillium crustosum and Penicillium commune were isolated identified from Pickled radish by colony counting method.Then,The antibacterial effects ofε-polylysine(P-Lys),nisin,tea polyphenols,natamycin and chitosan on these fungi were further studied.The results showed that P-Lys 60 ug/mL,nisin 60 ug/mL,tea polyphenols 75 ug/mL,natamycin 40 ug/mL and chitosan 400 ug/mL could completely inhibit the growth of spoilage bacteria.The combination of P-Lys to namycin and tea polyphenols showed a good synergistic effect.Finaaly,The composition of the compound preservative was determined by response surface methodology as follows:P-Lys 60 mg/kg,natamycin 35 mg/kg and tea polyphenols 400 mg/kg.The total number of colony was 4.4 x10~3 CFU/g after 3 weeks storage at 37 ~oC,which meet the food stardand for Pickled radish.The results of this study can provide a scientific basis for the application of composite preservatives. |
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