1. Selection and processing of apple raw materials: Apples with high maturity should be selected
cider
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Crisp apples must be free of diseases, insect pests, mildew, and green growth, and then be washed with drinking water and drained.
2. Crush and extract juice: First soak the apples in 2% potassium permanganate solution for 2 minutes, then take them out, clean them and peel them. When crushing, add 6% to 8% sodium sulfite, paying attention to the uniformity of the addition.
3. Clarification and separation: The freshly squeezed juice is very turbid. It is necessary to add pectinase and SO2 in time, mix thoroughly and then let it stand for 24 to 48 hours to separate before fermentation occurs. Since there is a lot of sediment produced and the structure is loose, it is advisable to use the siphon method with the straw gradually moving down to get the clear juice.
4. Add pectinase: Add 40 to 60 mg/L pectinase to freshly squeezed apple juice, treat it at 30°C for 8 hours, and then press to extract the juice. The resulting turbid juice is again treated with 50 mg/L pectinase. Clear juice can be obtained after treatment at 30℃ for 4 hours.
5. Adjust sugar content and acidity: The higher the sugar content of the fruit, the better. Generally, the sugar content is 5% to 23%. The juice must be adjusted before fermentation. Add sugar to make up for the insufficient sugar content, based on 1.7g sugar producing 1% alcohol. Organic acids can promote yeast reproduction and inhibit the growth of spoilage bacteria, increase the aroma of fruit wine, and give fruit wine a bright color. But excess not only affects the normal progress of fermentation, but also deteriorates the quality of the wine. The acidity should be adjusted appropriately before fermentation, generally about 0.8 to 0.0g per 100ml.
(2) Expanded culture of yeast
First-level culture: Take fresh apple juice and divide it into two sterilized test tubes. The volume of each tube is 10~20 ml, and add a cotton stopper. Sterilize at a pressure of 0.06 to 0.10 MPa for 30 minutes, cool to normal temperature, add 1 to 2 needles of pure yeast, shake to disperse, and culture at 25 to 28°C for 24 to 48 hours to make fermentation vigorous.
Secondary culture: Use a sterilized Erlenmeyer flask (1000 ml), fill 500 ml of fresh juice, sterilize as above, add two tubes of vigorously cultured test tube yeast liquid, and culture at 25-28°C for 24-28 hours , use after the vigorous fermentation period.
Third-level culture: Use sterilized Kastenberg jars or large glass bottles of 11,000 to 20,000 ml. Fresh juice should account for 70% of the capacity. The sterilization method is the same as before. Or add 150 ml of sulfur dioxide to one liter of juice for sterilization, leave it for a day and then inoculate yeast, that is, insert the secondary culture strain. The inoculation amount is 2% to 5% of the culture solution, and culture at 25-28°C. After 24 to 48 hours, the fermentation is vigorous and can be expanded again, or moved into a fermentation tank or fermentation tank for fermentation.
(3) Fermentation management
Initial fermentation period: It is the alcoholic fermentation stage, lasting 24 to 48 hours. During this period, the temperature should be controlled at 25-30°C, and ventilation should be paid attention to to promote the reproduction of yeast.
Main fermentation period: It is the alcoholic fermentation stage, lasting 4 to 7 days. When the alcohol accumulation approaches the maximum, the product temperature gradually approaches room temperature, the carbon dioxide bubbles decrease, and the juice becomes clear, that is, the main fermentation is completed.
Pressing out of the tank: After the main fermentation is completed, the fruit wine is in a clear state. First, open the wine outlet pipe of the fermentation tank and let the wine flow out on its own, which is called pouring wine. The remaining dregs can be pressed with a press and are called pressed wine.
Post-fermentation: The suitable temperature is about 20℃ and the time is about one month. After the main fermentation is completed, the original wine still contains a small amount of sugar. When changing the container, it should be ventilated and the yeast will be reactivated to continue fermentation and convert the remaining sugar into alcohol.
(4) Post-processing
1, clarification
Cider is a colloidal solution, a complex dispersion system with water as the dispersant. Its main components are water and alcohol molecules in the molecular state, while the remaining small parts are tannins, pigments, organic acids, proteins, and metal salts. Classes, polysaccharides, pectins, etc., which exist in the form of colloids (particle radius 1~100nm), are unstable colloidal solutions, in which physical, chemical and biochemical changes will occur, affecting its clarity and transparency. The purpose of the gluing and clarification operations during cider processing is to remove some factors in the wine that cause cider quality changes to ensure the stable quality of the cider during the subsequent shelf life, especially the physical and chemical stability.
2. Sterilization
Among cider quality indicators, sedimentation is an important issue affecting shelf life. Among them, biological precipitation is the main form of precipitation. In view of biological precipitation, the production process control should be strengthened to kill (suppress) bacteria in the juice making, fermentation, aging, filtration, and packaging processes. Strict aseptic filling conditions should be implemented to achieve aseptic filling and ensure the quality of the final product. Ensure safety during shelf life. Pasteurization is the most effective and safe sterilization method. During pasteurization, it can easily cause damage to the color, taste, and nutrients of fruit wine. It is generally not used in the production of mid-to-high-end fruit wine.
(5) Filling
The filtered cider must be filled in time, and a certain S02 concentration should be maintained during filling. Ascorbic acid and potassium sorbate must be added to the cider to prevent secondary fermentation.
Wang Yuantai (1997) believes that the pasteurization process (68~72°C, 35min or 85°C, 35min) can also be used before filling to reduce the possibility of secondary fermentation. The high-temperature and short-term treatment process has a negative impact on the wine. Flavor impact is minor. Qiu Dongmei et al. (2001, Jiangsu Suqian City Winery) believe that first sterilizing and filtering the wine, and then aseptic filling will have the least impact on the flavor of the cider. If necessary, after filling, the cider can be stored in bottles at 0°C to 2C for 6 to 7 months depending on the variety of cider. [2]
Other processing
1 The use of CaCl2 treatment can significantly improve the clarity of the juice, speed up the clarification of the juice, increase the acidity of the fermentation broth, and reduce the pH value of the fermentation broth. It has no significant effect on yeast alcohol fermentation and fermentation process. The cider brewed by CaCl2 treatment has high titration acidity, low residual sugar and low solids; it has pure, refreshing taste, light color and outstanding fruity aroma. When the juice processing time is less than 12h, it is appropriate to add 0.4g/L CaCl2; when the juice processing time is 18 22h, it is enough to add 0.3g/L CaCl2.
2. Add vitamin C to increase the acidity of the cider and lower the pH value of the cider. When the added amount of chromatic vitamin C is above 1.0g/L, it can inhibit the growth and reproduction of yeast. When 0.75g/L vitamin C is added to the delayed fermentation, the sensory quality of the cider is the best, with obvious apple aroma, pure and refreshing taste.
3. Adding sulfur dioxide can inhibit the reproduction of wild yeast and other microorganisms in the early stage of fermentation, delay fermentation, and facilitate the early clarification of juice. The color of apple cider decreases. As the amount of added wine increases, the color of cider decreases slightly. When 80mg/L sulfur dioxide is added, the sensory quality of cider is the best, with a slight apple aroma, a pure and refreshing taste.