| Uses the pumpkin as raw material,and acetic acid bacteria AS 1.41 as fermentation bacteria.the pumpkin vinegar was made by the methods of the surface static fermentation, Shake flask fermentation and Circulation fermentation under the under laboratory conditions. The research included the selection of acetic acid bacteria, the optimum condition of acetic fermentation,the flavor components of pumpkin vinegar of three different processes and the clarification of pumpkin vinegar, The results were as follows:(1) The acid produce amount and sensory properties were used as two main parmeters to select the appropriate vinegar fermentation strains. The results showed that the acetic acid beverage which was fermentation strains by AS 1.41 was 4.2 g/100 mL, which was increased about 4.7% than luniang1.01.It have good sensory indicators. On the standing condition, the determination of total acid content under different alcohol content, quantity and the different fermentation temperature. Using the orthogonal method to optimize the fermentation conditions. The results show that the optimal conditions for the temperature 28 ℃,8% alcoho1,5% acetic acid bacteria inoculum and the fermentation period was 10 d. At this condition the acid amount was 4.61 g/100 mL, makes its taste soft, while the colour was brownish yellow. The pumpkin was light and not greasy and the vinegar taste was outstanding.(2) The experiment was carried out to test the affection of different alcohol concentration,fermentation temperature,rotation rate,inoculation condition through determining the acid production,used orthogonal experiment to optimize process conditions of acetic fermentation,and the condition was observed. Finally, the optimum conditions were found as follows:temperature was 28 ℃, ethanol content was 8%, inoculation was 3.5%, fermentation period was 6h, acid production run up to 3.64/100mL. Pumpkin vinegar drink taste stimuliate, color yellow, alcohol taste, vinegar is not prominent.(3) Acetic acid bacteria was fermentation strain, fermentation process of circulating bed spray vinegar bacteria was studied by a carrier of bacteria bed (the corn cob, wood shavings, rice husk, reeds respectively)and Further investigated time trend for amount of acid produced, determining the optimum process parameters of vinegar making.The results showed that the corn cob was an excellent bed carrier.Best fermentation process of circulating spray vinegar:T=32 ℃,pumping capacity was 2.7L/min, inoculum concentration was 5.5%, ethanol content was 8%,production of acid1.93g/100mL.And it provides a certain theoretical basis for the late production of vinegar.(4) The aroma compounds of pumpkin vinegar drink by the methods of Circulation fermentation, submerged fermentation and the surface fermentation were analyzed by GC-MS, Aroma compounds were identified in pumpkin vinegar, static fermentation, submerged fermentation and and Circulation fermentation vinegar were28,18,17, respectively.The common components were pelargonic acid ethyl ester, D-limonene, benzaldehyde and keep the pumpkin aroma components of benzaldehyde.(5) Five clarifiers of pumpkin vinegar drinks including diatomite, gelation, chitosan and sodium carboxymethyl cellulose were used to obtain a scheme of clarifiers and process parameters. The results showed that the gelatin and chitosan were selected as the optimal clarify in single clarifying agent, meanwhile, light transmission rate of pumpkin vinegar drinks steady at about 90% after gelatin was compound with chitosan. The optimum condition:combined ratio of gelatin-chitosan was 3.2:8, quantity of addition was 2.0%, T=21℃,t= 3.6h.the light transmittance 97.9%. Accelerated test showed that the transmittance was not significant change, and was good for storage. |
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