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Wine fermentation technology
Wine fermentation technology July 23, 2009? 10:32 I. Process design

1. raw materials: the requirements for raw materials in self-brewing are relatively broad. Generally speaking, grapes with thick skin and tight flesh are better. If the requirements for self-brewing are not high, you can also use longan, Jufeng, rose and other varieties to make wine;

2. Process: picking ripe grapes ① → removing stalks and crushing ② → soaking in jars ③ → inoculating and fermenting ④ → stopping fermentation ⑤ → separating and pouring jars ⑤ → clarifying ⑧ → storing ⑧ → optimizing and adjusting ⑨ → filling and drinking ⑩.

3. See the schematic diagram of fermentation process below.

Second, the key points of the process

1、? Pay attention to choose grapes with neat fruit, bright color and no damage and mildew as raw materials for self-brewing. After selecting raw materials, pay attention to removing rotten branches and olives, and try to avoid contact with water and long-term storage. Nowadays, many self-brewing methods circulating on the Internet advocate washing and drying fruits, which is unscientific. On the one hand, washing away fruit powder, yeast and aroma substances, on the other hand, drying will reduce the freshness of fruit and affect the aroma quality of wine.

2、? If you brew it yourself, you can remove the stems and residual branches by hand. As long as the broken skin can make the juice flow out, it must be crushed, not necessarily crushed. Generally speaking, friends who make very little wine can crush it by hand. Common methods are: squeezing by hand, or putting into a container and tamping with a stick tool. In the case of a large amount of homemade wine, you can also consider manual crushing equipment, which has a simple structure and is mostly operated manually.

3、? The crushed raw materials are respectively put into fermentation containers, and the general filling amount is 80% of the container capacity, so as to reserve enough space to facilitate the discharge of carbon dioxide gas and heat during fermentation, and to prevent overflow or bottle explosion caused by gas accumulation; This needs to be explained: many small batches of self-brewed grapes can also be put into the jar first, then crushed and directly enter the inoculation and fermentation stage;

4、? At present, most self-brewed wines are naturally fermented, which often lasts for a long time and the aroma and color cannot be well controlled. Self-brewed winemakers or small wine cellars with high quality requirements have also begun to try to guide fermentation through artificial inoculation. Generally speaking, the fermentation temperature of dry red wine is controlled at 25? -28℃ is better, and it is best to keep the temperature constant to avoid big changes; At this stage, it is important to emphasize artificial sugar addition. At present, there are few scientific views circulating on the internet about adding sugar in self-brewing technology. In fact, the amount of sugar added is calculated according to the expected alcohol content, the target wine type and the original sugar content of grapes, not blindly added. At present, home-brewed families are mainly dry red. Generally speaking, 17.5 grams of sugar can be converted into one degree of alcohol. Before adding sugar, you should be careful about your raw materials and brewing goals. Then, according to this conversion rate, the amount of sugar added is calculated, and it is suggested that the sugar addition should be completed at the initial stage of fermentation to avoid the problem of incomplete fermentation in the middle and late stage of fermentation. (If you can scientifically add fermentation auxiliary materials according to the requirements of the process instructor, the effect will be better. )

5、? The judgment of the end of fermentation mainly depends on whether the alcohol content and sugar content are close to the expected index. A few homemade people usually taste the sugar content and observe the bubbles. Generally speaking, the end of fermentation can be regarded as very weak sweetness, and almost no bubbles float. At this time, the skin residue should be separated in time, and the separation and pressing process should be completed by filtering and pressing with fine gauze when the amount is small. When the quantity is large, you can consider squeezing the cage manually to help complete this step. On the one hand, if conditions permit, it is best to add 30PPM sulfurous acid to the separated juice.

6、? It is suggested to choose natural clarification or egg white-assisted clarification, that is, to stand for a period of time after separation without stirring, and then separate the clear night to remove the precipitated substrate, which takes a long time and the clarification effect is relatively poor. You can also add raw egg white and stir evenly to improve the clarification speed.

7、? The clarified wine will then enter the storage period, or be stored in cans or aged in oak barrels, all of which need to be sealed and emptied regularly for observation;

8、? Bottled drinking time can last 6- 12 months according to the preference of friends who brew it, but if it is brewed with fresh grapes, it can be drunk after three months, so it is not suitable for long-term storage. It is best to consume it within 1 year.

Third, matters needing attention

1, it is relatively difficult to start fermentation in a small container, so it is not appropriate to add too much sulfur dioxide in the early stage.

2. It is very important to control the temperature in the fermentation process, which should not exceed the dangerous temperature zone to prevent the fermentation from ending.

3. Stir once a day in the early stage of fermentation to provide an aerobic environment for yeast reproduction; Closed fermentation is needed in the later stage, because alcohol fermentation is carried out under anaerobic conditions.

4. After the fermentation, sulfur dioxide is added in time to prevent the yeast from metabolizing other substances and inhibit the activities of other microorganisms.