Diversity Of Filamentous Fungi And The Toxin-Producing Characteristics Of Typical Strains And The Toxin-Reducing Of Yeast In Dried Aquatic Products

Dried aquatic products are an important traditional aquatic processed food in China,which has also played a certain role in promoting the economic development of certain areas.At present,domestic research on it is mainly in the processing technology,but due to improper processing and storage conditions,the shelf life of dried fish is not very long,easy to mold and deteriorate,and thus contaminated by mycotoxins,causing harm to people's health..In order to understand the fungal pollution characteristics of dried aquatic products,this paper aims to reveal the diversity of fungi and its toxin-producing characteristics in the dry products of mildew and aquatic products,and to use the detoxifying enzymes of microorganisms to find out the parameters of mycotoxin reduction,in order to further construct the fish.The green reduction technology of mycotoxin in the dry provides theoretical guidance.The detailed research results and contents are as follows:1.Diversity of filamentous fungi in mildewed dried aquatic products.The investigation of filamentous fungi in 39 batches of dried aquatic products of mildewed in Zhanjiang,it was found that 137 strains of filamentous fungi were isolated from dried aquatic products,and 22 strains were isolated and purified.A total of 5 genera were identified,7 strains of Neurosporocrassa spp.,the fungus concentration was 2170CFU/g,accounting for 37.79%of the concentration of filamentous fungi,respectively:Alternaria alternata,Nigrospora sphaerica,Curvularia hawaiiensis,Curvularia lunata,Curvularia eragrostidis,Setosphaeria rostrata,Cladosporium tenuissimum;5 strain Aspergillus spp.,the fungus concentration of 1630 CFU/g,accounting for 28.38%of the concentration of filamentous fungi,respectively:Aspergillus europaeus,Aspergillus flavus,Aspergillus versicolor,Aspergillus fumigatus,Aspergillus aculeatus,3 strain Penicillium spp.,the fungus concentration of 1310 CFU/g,accounting for 22.81%of the concentration of filamentous fungi,respectively:Penicillium commune,Penicillium oxalicum,Penicillium commune;6 strains Fusarium spp.,the fungus concentration of was 433CFU/g,accounting for 7.54%of the concentration of filamentous fungi,respectively:Fusarium equiseti,Fusarium avenaceum,Fusarium Nelsonii,Fusarium sacchari,Fusarium oxysporum,Fusarium acuminatum,1 strain Trichoderma spp.,the fungus concentration 200 CFU/g,accounting for 3.48%of the concentration of filamentous fungi is Trichoderma harzianum.Therefore,the Alternaria spp.,Aspergillus spp.and Penicillium spp.and Fusarium spp.are the dominant filamentous fungi in the dried aquatic products.2.Toxicity characteristics of typical isolates and contamination of T-2 and AFB₁toxins in dried aquatic products of mildewed.There are a variety of fungi coexisting dried aquatic products of mildewed,which not only causes sensory deterioration of aquatic products,deterioration of quality,and reduction of nutritional value,but also these filamentous fungi produce mycotoxins under specific conditions.When the Fusarium is cultured alone,the toxigenic ability is extremely weak or basically not produced.The same is true when the Aspergillus is cultured alone,but if both the Fusarium and the Aspergillus are cultured together,the yield of both toxins is high.Foods contaminated with mycotoxins are a serious food safety issue once they are ingested by humans and animals.However,39 batches of dried aquatic products of mildewed in Zhanjiang market were analyzed for moldy early stages and moldy late stages,it was found that T-2 and AFB₁ toxins has disappeared were biotransformed and biosorbed due to the presence of yeast.3.Screening and characteristics of yeast in Salted fish.Yeast can reduce mycotoxins,control the fungal toxin contamination,obtain strains with excellent production performance,the PDA solid medium plate coating method of sampling was to quantitatively separate and purify yeast from kippers,and to study the growth temperature,the acid resistance and nitrite tolerance ability of dominance salt-tolerant yeast strains.The results showed that 436 strains of yeast were isolated from15 kinds of salted marine fish and 9 strains of yeast were obtained after purification.Finally,7^#Meyerozyma guilliermondii and 9^#Kodamaaea ohmen with the better salt tolerance ability were selected by cultivated with YPD liquid medium of different NaCl content from 9 strains of yeast,salt tolerances reach 9%and 12%respectively.And they were found that the optimum growth temperature were between 28³2?,the optimum pH was between 5⁶,the optimum content of nitrite was less than 100 mg/kg.The dominant strains obtained have good growth performance in Salted fish.In the future,the yeast strains with excellent performances such as 7^#and 9^#can be applied to the high-salt food matrix to exert their superior effects.4.The depletion effect of yeast enzyme preparation on T-2 and AFB₁ toxin in Dried Lutianus Erythropterus.By using the yeast phase II detoxification enzyme activity to reduce the mycotoxin,it can be seen that the yeast contains phase II detoxification enzyme,and the enzyme activity is best in the stable phase?16³2 h?of the yeast,and the enzyme activity in turn is GSTs>SULT>AANAT>MT>UDPGT;after of both type A and type B preparation,it was found that the phase II detoxification enzyme activity of type A preparation was at a higher level in the stable period of the bacteria,and the phase II detoxification enzyme did not change significantly throughout the whole process of type B preparation;in the Dried Lutianus Erythropterus matrix,the phase II detoxification enzymes of the A and B preparations showed the same tendency as the enzyme activity:the five enzymes were inhibited in 4 h,with time Prolonged,the enzyme activity is gradually stimulated,and the activity of the enzyme begins to decrease with the prolongation of time,which is the first to decrease,and then to the increase after the to decrease"inverted S-type"trend;the degradation rate of the T-2 toxin of the type A preparation is 50%.The degradation rate of AFB₁ toxin was 55%,which had obvious degradation effect;the degradation effect of B-type on T-2 toxin was not obvious,and the degradation rate of AFB₁ toxin was 42%.