Study On The Processing Technology Of Auricularia Auricula Apple Vinegar

At present, the study on auricularia auricula Apple Vinegar in China has been less documented. The function of auricularia auricula Apple Vinegar is a combination of the health function of auricularia auricula and the fruit vinegar, which is of great nutrition and taste. Besides, it also has many functions, such as nourishing, improving constitute, enhancing immunity and so on.In this study, we chose the auricularia auricula spawn and concentrated apple juice as the main raw materials. The technology of the submerged fermentation, the alcohol fermentation and the acetic acid fermentation of auricularia auricula Apple Vinegar was studied and optimized by orthogonal test and response surface experiments. The sensory evaluation was also carried out. Our main study includes:1.The orthogonal test of the factors, including carbon source, nitrogen source and inorganic salt, was carried out to find out the effects of the factors on mycelial dry weight and crude extracellular polysaccharide content. Eventually, the optimal fermentation medium consisted of the following: glucose 3.5g/100mL, bean cake powder 0.9g/100mL, KH₂PO₄ 0.5g/100mL, MgSO₄·7H2O 0.25g/100mL.2.The effects of different fermentation conditions on the submerged fermentation by single factor experiment were studied. The results showed that the most mycelial dry weight and crude extracellular polysaccharide content were obtained when the conditions were as follows: culture time 7 days, temperature 28℃, inoculation amount about 10%, initially natural pH value (about 5.4), 100mL liquid in 250ml volumetric flask, the rotation speed 150rpm.3.The optimum conditions of the synergistic effect of ultrasonic combined with repeated freeze-thaw, were obtained according to orthogonal test as follows: freezing time 30min, wall-breaking time 25 min and twice.4.The dynamic curve of the submerged fermentation of auricularia auricula Apple Vinegar was also studied. The result showed that, the amount of residual sugar in fermentation broth decreased with the progress of the fermentation time. The mycelial dry weight increased and reached the maximum value as 1.95g/100mL at 84h. The amount of crude extracellular polysaccharide was also continuously increasing further to 0.51g/100mL at 96h.5.We obtained the regression equation through Box-Behnken four factors and three levels experiment by taking initial sugar content (X₁), fermentation temperature (X₂), pH value (X₃) and inoculation amount (X₄) as the factors, and taking the alcohol degree as the index.The equation was Y=6.66667+0.1275X₁+0.148333X₂ +0.154167X₃+0.126667X₄-0.00875X₁²-0.26X₂²-0.15125X₃²-0.1X₄2-0.0425X₁X₂+0.125X₁X₃+0.08X₁X₄-0.0325X₂X₃+0.135X₂X₄-0.135X₃X₄. The alcohol degree reached the maximum (Y=6.95mL/100mL) at X₁=0.231, X₂=0.315, X₃=0.935, X₄=0.148, and it has been proved by the experiments.6.The continuous culture was performed by inoculating 5% yeast at 28℃to obtain the dynamic curve of ethanol fermentation. The result showed that the sugar degree decreased and the alcohol degree showed an increasing tendency in the whole alcoholic fermentation process. At the first 2 days of the fermentation, the sugar degree continuously decreased while the alcohol degree slowly changed. After 2 days, the fermentation became obviously, with the development of abundant gas bubbles and heavy vinosity and rapid decreased of the sugar degree. After 6 days, the sugar and alcohol degrees remained steady, the mycelium and partial metabolin precipitated, the content of alcohol reached the maximum and glucose consumption reduced to minimum, the reaction slowed down. After 7 days, the alcohol degree remained steady, the sugar transition finished basically, the reaction was over.7.We obtained the regression equation through Box-Behnken three factors and three levels experiment by taking initial alcohol degree (X₁), fermentation temperature (X₂) and inoculation amount (X₃) as the factors, and taking the acid content as the index. The equation was Y=4.50667+0.125X₁+0.6875X₂+0.0625X₃- 0.04833X₁2-0.05583X₂2-0.04583X₃2-0.0025X₁X₃+0.0375X₁X₂+0.015X₂X₃. The acid content reached the maximum (Y=4.6676mL/100mL) at X₁=0.872, X₂=0.183,X₃=0.432, and it has been proved by the experiments.8.The acetic acid fermentation was performed by inoculating 5% acetic acid bacteria at 28℃to obtain the dynamic curve of the fermentation. The result showed that the alcohol degree decreased gradually and the acid degree continuously increased in the whole fermentation process. At the first 2 days of the fermentation, the alcohol and acid degree slowly changed as the acetic acid bacteria was in adaptation period and had slow growth. After 3 days, the fermentation became obviously, with rapid decreased of the alcohol degree and increased of acid degree, which was the main stage of the process. After 7 days, the alcohol and sugar degrees remained steady, the content of acid reached the maximum. After 8 days, the alcohol degree remained steady, and the content of acid had little decline, the reaction was over.9.The optimum blending proportioning was obtained through L9(34) orthogonal test as follows:10% auricularia auricula Apple Vinegar (v/v), 40% concentrated apple juice (v/v) and 10g/100mL sucrose. The product is favorable with natural gold yellow, good flavor and great taste.