Screening And Identification Of Antifungal Lactic Acid Bacteria And Its Application In Yogurt Antiseptic

With the progress of science and technology people’s living standards improvement,people pay more and more attention to food safety,especially on food additives.Consumers are more inclined to buy"pure natural food" without additives,this trend promote the development of new biological preservative.Lactic acid bacteria and some of their metabolites have a strong inhibitory effect,which indicates their potential to become natural preservative,especially for inhibiting mold and yeast.In this paper,lactic acid bacteria and fungi were isolated from corrupt dairy products,fruits,vegetables and silage.The lactic acid bacteria and fungi were screened and the dominant resistant lactic acid bacteria and fungi were identified.The dominant strains were used as auxiliary fermentation agents as yogurt preservative.The results are as follows:1.64 strains of lactic acid bacteria and 14 strains of fungi were isolated from the experimental materials.2.The results showed that 14 strains of lactic acid bacteria could inhibit the three fungi by double plate method and Oxford cup method.The dominant lactic acid bacteria and fungus were identified by biological means.Lactic acid bacteria are Lactobacillus plantarum,Lactobacillus paracasei,Lactobacillus rhamnosus and Enterococus faecium;3 strains of fungi are Aspergillus niger,Geotrichum candidum and Pichia pastoris.B9 on the Aspergillus niger’s largest inhibition zone of 21.11 mm,B9 against the Geotrichum candidum to 17.35 mm,B10 Pichia pasta reached 17.68 mm.3.After selection,the preponderant lactic acid bacteria were added to the yogurt fermentation as an auxiliary fermentation agent,it was found that yogurt fermented by nine kinds of lactic acid bacteria has good physical and chemical characteristics,which indicated these nine kinds of bacteria could be good fermentation agents;at 4 ℃,suppression time of M1,B10 to experimental group sprayed with Geotrichum candidum can be 28 days,The inhibition time of B9 to Aspergillus niger group was 28 days,and the inhibition time of B10 to Pichia pastoris was 27 days.At room temperature,the Aspergillus niger group was mildew at the 168th hour,and Pichia pastoris appeared mildew at the 144th hour.Lactobacillus plantarum B9,B10,M1,P10 have the potential for long shelf life yogurt starter.