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Objective: Liquid black garlic was prepared from fresh garlic and the effect of Streptococcus thermophilus on the quality of liquid black garlic was studied. Methods: Fresh garlic was inactivated with alliinase at 180 ℃, then broken and added with Streptococcus thermophilus. Using the inactivated garlic without Streptococcus thermophilus (blank) as reference, the effects of Streptococcus thermophilus ratio, different alliinase inactivation time and their coexistence time on the quality of liquid black garlic were studied. Results: The optimal time for inactivating allinase in garlic at high temperature was 9 min, the optimal proportion of Streptococcus thermophilus was 5%, the optimal coexistence time of Streptococcus thermophilus and inactivated crushed garlic was 32 h, and the fermentation time required in a constant temperature and humidity fermentation tank at 80 ℃ was 15 d. All quality indexes reached the fermentation standard of black garlic. Compared with blank black garlic, the total phenol content of liquid black garlic was 2 times, the total acid content was 1.9 times, the reducing sugar content was 1.3 times, the DPPH· clearance and ·OH clearance were 1.5 times and 1.46 times, respectively. Conclusion: Streptococcus thermophilus can promote the fermentation of black garlic, improve its quality indicators, shorten fermentation time and have great application prospects.

Using black garlic, lentinus edodes, and millet pepper as main raw materials, the formulation of black garlic lentinus edodes sauce was studied by single factor, fuzzy mathematical evaluation, orthogonal design, and response surface methodology, and its microbial and physicochemical indexes were determined. With the commercial Zhongjing lentinus edodes sauce and mengshanhong lentinus edodes sauce as the reference, the antioxidant properties were determined and analyzed, and the preservative potassium sorbate was added to investigate the storage time. The results showed that the optimum formula was 20 g black garlic, 21 g lentinus edodes, 3.6 g millet pepper, 6.6 g oil, 3.3 g sugar, 3.3 g onion, ginger and garlic respectively, 13.2 g bean paste, 4.4 g salt and 4.4 g starch. At this time, the sauce products taste sweet and soft waxy, spicy and delicious, bright color, moderate consistency. In the range of 0.05~1 mL/mL volume concentration, the scavenging rate of DPPH• and •OH free radicals was the strongest, which was higher than the commercial Zhongjing mushroom paste and Mengshanhong mushroom paste, with significant difference (P