春草莓表面霉菌鉴定及其致腐能力研究

目的调查春草莓表面霉菌的总体状况,对主要致腐真菌进行致腐能力和产毒素研究,为草莓的保鲜及食用安全评价提供理论依据。方法对60份春草莓样品进行霉菌检测,分离霉菌采用ITS序列测序方法进行鉴定;利用高效液相色谱法及酶联免疫法对腐烂草莓及真菌发酵液中赭曲霉毒素A(ochratoxin A,OTA)和展青霉素(patulin,PAT)进行检测,对出现率较高的霉菌进行草莓复接试验,判断其致腐能力。结果健康草莓表面的霉菌计数对数值3.5~5.5的占样品总数的83%;毛霉菌属、枝孢菌属和青霉菌属在草莓中出现率较高;由这3类霉菌致草莓腐烂样品和其发酵液均检测不出真菌毒素OTA和PAT,复接试验中毛霉属真菌在36 h在草莓表面形成明显菌斑,72 h可形成明显菌斑而更大面积软腐。结论草莓表面存在大量且多种霉菌,霉菌侵染草莓是导致其腐烂主要诱因,毛霉属霉菌占主要生态位但青霉菌属、枝孢菌属霉菌更易导致其软腐,草莓表面霉菌不会产生真菌毒素而对草莓进行二次污染。

Identification and capability of causing-spoilage of moulds on strawberry

Objective To investigate the general condition of the molds on the surface of spring strawberry and their capabilities of causing-spoilage and producing toxins, so as to provide the theoretical basis for the preservation and safety evaluation of strawberry. Methods The moulds of 60 spring strawberry samples were tested and the isolated moulds were identified by ITS sequencing. The ochratoxin A (OTA) and patulin (PAT) in spoilage strawberries and mould fermentation broth were detected by high performance liquid chromatography (HCLP) and enzyme-linked immune sorbent assay (ELISA). Multi-joint tests of strawberry were conducted to moulds with high incidence to assess their capabilities of causing-spoilage. Results For the fresh strawberry, the samples on which there were moulds with the logarithm values of 3.5~5.5 accounted for 83% of the total samples. The occurrence rates of Mucor sp., Mycobacterium sp. and Penicillium sp. in strawberry were relatively high and OTA and PAT could not be detected in the fermentation broth and spoilage strawberry samples caused by the three moulds. In the multiplex tests, the Mucor sp. formed obvious plaque on the surface of strawberry after 36 h and caused strawberry soft and putridity after 72 h. Conclusion There are various moulds with large numbers on the surface of strawberry and their infection to strawberry is the main cause for its spoilage. Mucor sp. account for the main ecological niche but Penicillium sp. and Cladosporium sp. are more likely to lead to the softness and rot of strawberry, however, the moulds on the surface of strawberry will not bring a secondary pollution by producing mycotoxins.