A Study On Brewing Techniques And Flavor Substances Of High Quality Apple Vinegar

The crux of maintaining the apple industry developing steadily and healthily is to enhance its benefit in pace with the increasing of apple quantity and the development of apple industry. New apple products development is an important way to raise the benefit. Now that the products of acetic acid fermentation have good market vista, the base to stable and develop the market is the application of advanced techniques and the enhancement of its quality. On the base of home and foreign resources of apples and Acetobacteria strains, beginning with the application of apples to the production of apple acetic acid fermentation products, in the ways of basic microbial techniques, advanced fermentation and analysis techniques and microbial aroma-enhancing techniques, the research works of apple vinegar brewing techniques and measures of enhancing acidification ability and flavor quality have been conducted. Conclusions have been drawn as the following:1. High quality apple vinegar which have good acid tastes, aroma and color characteristics of apple can be produced by utilizing deep acetic acid fermentation and immobilized cell fermentation process.2. Three new good Acetobacteria strains of AM2 AM4 and CPi are separated and determined in the experiment, of which AM2 and AM belong to A.mesoxydans with pole flagellum, and CPi belongs to A.rancenns with periphery flagellum; AM2 is the most suitable one to apple vinegar brewing.3. "Rails" is suited to form good acid taste and color quality, "Mstsu" and "Gooden. Delicious" are most suited to form good aromas, then "Fu Ji" and concentrated juice produce bad color of vinegar.4. There are more than 50 kinds favor compounds in apple vinegar. Acetic acid, malic acid, oxalic acid, citric acid, lactic acid and succinic acid are major organic acids in fermented apple vinegar. Ethyl acetate, ethyl lactate, ethyl octanoate and ethyl hexanoate are the major esters in it.5. The fermentation circle time of immobilized cell in shaking flash culture are in 42 hours with acid producing speed 0.8g/L h and the ration of ethanol to acid 75% which are more higher than immovable liquid fermentation of entrapped cell and batch liquid fermentation.6. The main factor affecting the acid growing speed in shaking culture is the relative volume content of fermented liquor in shaking flask, and the main factor affecting the ration of ethanol to acid is the fermentation temperature. The ADH enzyme activity of Acetobacterias has linear relation to the acid content, which has positive relation before 60 hours.7. The main factors that affected the immobilized cell fermentation are the aerating state and the even moving degree of fermented liquor. All the temperature, ethanol contents shaking speed and cell relative volumes affect the proliferation of immobilized Acetobacteria and the fermentation result.8. Apple varieties and fermentation technical processing are the main factors influencing the kinds and content of flavor substances in apple vinegar. The content of malic acid, succinic and lactic acid is cut down during the metabolism of Acetobacteria and the kind of volatile esters increase and its whole content goes down in the fermentation process. Ester contents especially ethyl acetate can be increased by utilizing technical ways as ester-producing yeast, ester synzme.