Fermentation Technique For The Production Of Wax Gourd With Strong Odour(a Traditional Chinese Food)

Fermented wax gourd with strong odor is popular in eastern of Zhejiang province as a traditional food.In this paper,we worked to obtain valuable information about it.The results and findings were summarized as follows:Fifteen bacterial strains were identified from naturally fermented wax gourd with strong odor,among these,six were deemed to valuable for the ferment.They are Corynebacterium minutissimum,Bacillus pumilus,ShewaneIla putrefaciens,Hansenula anomala,Saccharomyces cerevisiae and Lactobacillus plantarum.Their optimum temperature were all 30℃.The optimum growth pH of Hansenula anomala, Saccharomyces cerevisiae,Lactobacillus plantarum,Shewanella putrefaciens,Bacillus pumiIus,Corynebacterium minutissimum was 8,7,6,6,7.5 and 4.5;respectively.Each strain grew well as salt-tolerant between 0%to 5%.Among 20 combination of isolated strains,two of them were good in flavor formation: (1) 2%Bacillus pumilus,2%Shewanella putrefaciens,2%Hansenula anomala were inoculated;(2) 2%Bacillus pumilus,2%Shewanella putrefaciens,2%Corynebacterium minutissimum inoculated,and 2%Hansenula anomala and 2%Saccharomyces cerevisiae were inoculated after three days.Through orthogonal tests,the panel organoleptic evaluation indicated that optimum mode of inoculated strains was 2%Bacillus pumilus,2% Shewanella putrefaciens,2%Hansenula anomala were inoculated in wax gourd juice which including 1%salt.The inoculated liquids were fermented for 10 days at 30℃,then wax gourd was put in to continue the fermentation for another 10 days at 30℃.The pH value decreased,and the total acid content increased both in naturally and inoculated fermentation.At the end of fermentation,their total acid content were 2.4%and 2.3%,much higher than normal fermented vegetables such as Kraut(about 1%).Although there were large quantities of organic acids such as butyric acid,hexanoic acid,pentanoic acid present in the product,wax gourd with strong odor tasted not so sour.Very little nitrite was monitored in two processes,manually inoculated or natually fermented.The flavors of the product of natural and inoculated fermentation were studied by HPLC and GC-MS.Results indicated that their flavor substances were analogously,but a little compounds with possibly nocuous was found in inoculated fermentation production, so,further investigation on the safety of the inoculated ferment product was need to carry out.