Study On Processing Technology For Litchi Vinegar

Litchi (Litchi chinensis Sonn.) is representative fruit of tropical and subtropical regions. It is rich in nutrition and it has very high value on food and medical care. Using litchi as raw material to develop litchi vinegar, not only is an important way to improve the efficiency of litchi industry, but also can increase the types of vinegar. In the present paper using litchi wine as raw material to make litchi vinegar in different fermentation ways. Optimized the fermentation conditions of Liquid Standing fermentation (Lst) and Liquid Flask (Lfl) fermentation, researched the effect of nutritional factors on acetic fermentation. Compared the total antioxidant capacity, amino acid content, volatile flavor components of litchi vinegar in different fermentation ways. Analyzed the changes of volatile flavor components of litchi fruit vinegar in the aging process. Clarified the litchi vinegar and made the litchi vinegar beverage for drinking directly. The results were as follows:1. The total acidity was used as index to optimize the fermentation conditions of Liquid Standing fermentation (Lst) and Liquid Flask fermentation (Lfl). The Lst parameters were:initial alcoholity,9.00%; inoculation amount,5.00%; temperature,27℃and the volume loading in500ml flask,100ml. Under the condition, litchi vinegar had73.66g/1acidity, the inversion rate was78.46%. The Lfl parameters were as follows: initial alcoholicity,7.00%; inoculation amount,5.00%; temperature,27℃and the volume loading in500ml flask,100ml. Under this condition, litchi vinegar had69.72g/1acidity the inversion rate was95.48%.2. The litchi wine containing7.00%alcohol was used as raw materials to make litchi vinegar with Machine-Stir fermentation (M-S), Self-Priming fermentation (M-P) and Solid-State fermentation (S-S). Finally, litchi vinegar had35.55g/1,65.63g/1and31.12g/1acidity, the inversion rate was48.68%,89.87%and44.19%, respectively.3. Added16kinds of different nutritional factors to litchi vinegar with9.00%initial alcoholicity to get the purpose of increasing total acidity and inversion rate, the result showed there were six kinds of factors(NaH2PO4, CaCl2, K2SO4, NaAc,(NH4)SO4, MgCl2) can increase total acidity significantly, four kinds of factors(NaNO3, MgSO4, KH2PO4, Na2HPO4) can make it while the effect was not apparent, two kinds of factors (CuSO4, CO(NH2)2) can inhibition the fermentation process. The residual four kinds of factors(MnSO4, NaSO4, NH4C1, FeSO4) can increase the total acidity, while they cannot increace the total acidity during fermentation process.4. Compared total antioxidant capacity, amino acid content, volatile flavor components comprehensively, it can be seen that Self-Priming fermentation was the better way to make litchi vinegar. 5. According to the effect of different clarifications on the litchi vinegar, chitosan was selected as the optimal clarifier, when the dosage was20mg/1, the light transmittance can reach to98.15%.6. Used the orthogonal experimental to optimize the recipe, it was confirmed that the litchi vinegar beverage which contain original vinegar30%, sucrose10%, honey7%, litchi juice10%. According to the proportion, litchi vinegar beverage can be drinked directly mixing with the sweetness of litchi and vinegar aroma.7. During the aging process of litchi vinegar for six month, the content of soluble solids and total acids were decreased, varieties and content of volatile flavor compositions can reach the peak in the litchi vinegar which stored for3months in the oak barrels.