| The moon cake is a kind of Chinese traditional baking food,which is popular with people for its variety,unique favour and rich nutrition,and the consumption of moon cakes is very great although they were only prepared for Mid-autium Day.Because moon cakes have high content of fats and sugars,so they are oxidated and decayed easily,and microbial contaminations are usually happen in procedures of production and storage.The number of moon cake manufacturing enterprises is large in our country.Furthermore,many of them are small and medium enterprises. Therefore,the quality of moon cakes has always been the focus of attention.Most of current studies on moon cakes' microbial flora are focused on investigation of food hygiene and identification of mold strains that can arose spoilage.And that there are little studies on bacteria and yeasts in moon cakes.So the objective of this study is to understand the dominant microorganisms in Guangdong moon cake on bases of mensurating the number of microorganisms and identifying strains that were isolated from them.This may provide us with theoretical foundations to control the quality of moon cakes in producing.In this paper,Guangdong moon cake which is one of types with large consumption in market was choosed as objective to analyse its main physicochemical indexes,aerobic plate count,and enumeration of molds and yeasts Then the dominant microbial flora including bacteria,yeast and molds were isolated and then identified using classical microbial identification methods.The results are useful for us to know the strains that may be found in moon cakes and to understand their quality and hygiene.The conclusions of this study as follows:(1) It was found that the dominant microorganisms in Guangdong moon cakes were bacteria. Most of total plate counts in samples were under 100 cfu g-1.The second dominant microorganisms were mold strains,most of enumeration of molds in samples were below 50 cfu g-1 except in these samples in which molds had been grown.And enumeration of molds in samples that were produced in the year of 2008 was larger than it in samples that were produced in the year of 2007.The yeasts were only detected in three samples that were produced in the year of 2007.(2)The moisture content,total sugar content,fat content and protein content of Guangdong moon cakes were in the range of 11.3%～21.2%,16.0%～42.5%,11.5%～19.7%and 6.6%～17.5%.The scopes of these indexes were stable.The total sugar content and fat content were higher than another two indexes.Even there was great difference between the same physical and chemical factors of two moon cakes with the same style because of their different processing parameters.(3) Gram-positive bacteria,including Bacillus and Streptococcus,were dorminant strains in Guangdong moon cakes.There were 10 Bacillus strains and 5 Gram-positive cocci strains were isolated and identified,namely B.subtilis,B.cereus,B.licheniformis,B.pumilus,B.macerans,B. megaterium,B.brevis,B.coagulans,B.polymyxa and B.circulans.The detection rate of B.subtilis in these samples that were produced in the year of 2007 and 2008 were 26.3%and 20%respectively and B.subtilis was the species with highest detection rate.The 5 Gram-positive cocci strains,i.e. Micrococcus luteus,M.varians,Staphylococcus xylosus,S.epidermidis and S.saprophyticus.The detection rates of Gram-positive cocci in samples that were produced in the year of 2007 and 2008 were 20%and 35%respectively.(4) Only five yeast strains were detected in three samples that were produced in the year of 2007,and none was found in the next year's samples.The five yeast strains were Rhodotorula glutinis,Cryptococcus albidus,Trichosporon pullulans,Sporobolomyces albo-rubescens and C. terreus.(5) There were nine Aspergillus spp.were isolated and identificated,i.e.A,fumigatus,A. fisherianus,A.wentii,A.versicolor,A.costiformis,A.flavus,A.sydowii,A.aureolatus and A. heyangensis;Geotrichum candidum and G.ludwigii.Furthermore,there were two Geotrichum spp were also found,namely G.candidum and G.ludwigii.Penicillium variabile,Paecilomyces spp., Cladosporium spp.,Phacodium spp.and Fusarium spp.were also isolated and identified in these samples.(6) There are more species of molds were found in samples that were produced in the year of 2008 compared with species of them were isolated from samples that were produced in the year of 2007.Aspergillus versicolor was the dominant.mold with highest detection rates.The detection rate of Aspergillus versicolor in samples that were produced in the year of 2007 and 2008 were 40%and 20%respectively.
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