First, grape juice

Grape juice is generally produced by continuous hot pressing.

Technical points

The raw materials for cleaning grapes should be mature and full, with good color. They should be harvested in time, then mixed and sorted, and sprayed vigorously.

Crush berries with a beater, and don't crush seeds when crushing.

Preheating in the preheater to 60 ~ 62.7℃ 15 minutes, so that a large number of pigments, pectin and some tannins in the peel and seeds are dissolved. In a certain range, the higher the heating temperature and the longer the heating time, the darker the color and the thicker the texture of grape juice. But over-heating, tannins are extracted from seeds and peels, which makes the taste of grape juice too astringent. In the usual heating time, the temperature should not exceed 65.5℃.

Adding enzyme and wood fiber 0.2% pectinase preparation and 0.5% refined wood fiber to grape pulp is beneficial to continuous pressing and can improve juice yield. The digestion of grape pulp is usually carried out in a large storage tank with a stirrer. The agitator evenly mixes the enzyme preparation, wood fiber and grape pulp, and stays in the tank for 30 minutes to complete the digestion process.

The methods of squeezing grapes include continuous squeezing method, hydraulic press squeezing method and so on.

Screening Some squeezing and screening are carried out at the same time, while others need to screen the squeezed juice separately. Suspended solids in fruit juice can be removed by sieving, and 1% ~ 2% diatomite filter aid can be added during filtration. You can also use a continuous automatic cleaning separator to remove suspended solids, and then use a plate or plate-frame filter to filter, and diatomite is used as a filter aid during filtration.

Clarification often adopts cold storage method, quick freezing method, salt adding method, enzyme adding method and freeze concentration method to clarify grape juice.

The clarified grape juice after canning and pasteurization first passes through a basket or plate heat exchanger (above 76.6℃), then enters a canning machine for canning, and then is pasteurized.

Technical points

Any grape can make wine, but high-quality wine has certain requirements on variety, maturity and sugar content. Excellent varieties used for red wine brewing are: gems, French orchids, Jiali wine, Merlot and so on. Excellent varieties of liquor include Riesling, Boya, White, Pepsi South, Baiwuni, Guirenxiang and so on. The sugar content of grapes should be above 16%, and the acid content should be below 1.0%.

Rotten and immature fruit particles should be removed before crushing and deodorizing. Grape grains should be fully broken, but seeds and fruit stalks should not be broken. Sulfuric acid is added during pressing to make the grape juice contain 100× 10↑(-6) sulfur dioxide. The raw materials of red wine need to remove the fruit stalks. De-stalking can be carried out before, after and at the same time of crushing and de-stalking, and a grape crushing and de-stalking combined machine can be used. Do not remove the raw materials of liquor, and press them immediately after crushing. The fruit stalk is used as a filter aid to improve the filtration speed.

Squeezing and clarifying to make red wine is to directly ferment the raw materials after crushing, and then squeeze and take out the new wine after the main fermentation is completed. To make white wine, the juice should be fermented. Before fermentation, crushed fruit particles need to be squeezed to obtain juice and clarify it.

The alcohol content in fruit wine comes from the sugar in fruit juice. Generally, the sugar content of grapes is about 14% ~ 20%, and the alcohol content can only be about 8.0 ~1.7. Generally, the alcohol content of wine is 12 ~ 18, so sugar is needed. According to the determination, 100 ml fruit juice contains 1.7 g sugar, which can produce 1 degree alcohol. The amount of sugar added is determined by measuring the sugar content in grape juice before fermentation, and it is gradually added to the fermentation broth in three times. The best way to increase the sugar content of fermentation broth is to concentrate part of the juice under reduced pressure to increase the concentration and add supplements. The acid content in fruit juice should be 0.6% ~ 1%. This amount is not only suitable for yeast, but also can inhibit miscellaneous bacteria, so that wine has the best flavor When the acidity in fruit juice is too high, syrup or fruit juice with low acidity can be added for adjustment, and neutral potassium tartrate can also be used for neutralization. If the acidity in the juice is too low, it can be adjusted with citric acid.

The fermentation containers needed for red wine fermentation are: fermentation barrel and fermentation pool. Fermentation barrels are generally made of oak wood or chestnut wood, and the existing stainless steel fermentation tongs are divided into open and closed types. Fermentation tanks are made of reinforced concrete, stones and bricks, and are divided into open and closed types.

The brewing of red wine requires high fermentation intensity and high temperature to facilitate the extraction of pigment and tannin. Because red wine has many tannins and strong bactericidal ability, open fermentation is generally used. The low fermentation temperature of liquor is beneficial to the production of aromatic substances. In addition, when liquor is fermented, there is less tannin and the ability to inhibit miscellaneous bacteria is weak, so closed fermentation is adopted.

Pour the treated fruit pulp into a sterilized fermentation container, and pay attention that the amount of fruit pulp should not exceed 4/5 of the container. Let it ferment naturally or add 3% ~ 5% or even 10% yeast, and the yeast is in a vigorous culture period. The temperature is controlled at 25 ~ 30℃. At this time, it is the stage of yeast reproduction, and a large number of bubbles appear on the liquid surface, so we should pay attention to providing a certain amount of air. This stage is the initial stage of fermentation, which generally lasts for 24 ~ 48 hours. Followed by the main fermentation period, lasting 4 ~ 7 days, mainly alcohol fermentation stage. At this time, a large amount of alcohol is produced, the sugar content of pulp is reduced, and a large amount of carbon dioxide is produced, forming a "wine cap". The "wine cap" should be pressed under the liquid surface with a perforated plate, which is conducive to the dissolution of pigments and aromatic substances in the skin in the wine. Because the activity of yeast will raise the temperature of fruit wine, measures should be taken to prevent the temperature from rising and keep the temperature below 30℃. When the sugar content is stable at 1% and the temperature drops to room temperature, the main fermentation is finished. After the main fermentation, it should be discharged from the barrel (pool) in time to avoid excessive leakage of bad substances in the dregs and affect the flavor of the wine. The wine that flows out without pressure is called gravity wine, which has the best quality. The pressed wine is called pressed wine, which is of poor quality, and the residue can be used as distilled wine. After the main fermentation is completed, there is a small amount of sugar in the original wine, and the yeast will revive when it meets the air after the wine is produced. It should be put into a container for post-fermentation. The post-fermentation period is about one month, and the suitable temperature is 20℃. At the end of post-fermentation, the sugar content decreased to about 0.65438 0%. The newly brewed wine is turbid and spicy, so it is not suitable for drinking and must be aged. The aging process needs adding barrels, changing barrels, gluing and cold and hot treatment. In the aging process, the volume of liquor should be reduced, and there will be a gap at the top of the container, so the gap should be filled with the same batch of liquor in time. During the aging period, the wine gradually clarified and precipitated, and it was necessary to change barrels. Generally, the barrel is changed once in the winter of that year, once in the spring and autumn of the following year and once in the third year 10- 12. Wine is generally stable and transparent after being stored for a long time and changing barrels for many times, but sometimes it is difficult to precipitate because the suspended matter in wine has the same charge, which repels each other and cannot be condensed, and is hindered by colloidal solution. In order to speed up the clarification of fruit wine, methods such as adding glue, cold and hot treatment and centrifugal filtration are often used.

Liquor fermentation Liquor fermentation is basically the same as red wine. The difference is that the clear juice is fermented in a closed fermentation container. White grape juice generally lacks tannin, and 4 ~ 5g tannin is often added to100L juice before fermentation. Fermentation temperature generally needs 65 08 ~ 20℃.

The composition of the blended wine is extremely complicated. In order to maintain the inherent characteristics of wine quality, alcohol content, sugar content and acid content should be blended according to the quality requirements of finished products before leaving the factory. The alcohol content should be mixed with distilled liquor or deodorized alcohol of the same variety. Acidity can be supplemented by citric acid or neutralized by neutral potassium tartrate, and sugar content can be supplemented by white sugar. The color of red wine is too light, so it can be blended with dark wine, and the natural essence similar to fruit must be used to enhance the fragrance.

Fine filtration is required before bottling, sterilization and bottling. The wine bottle is sterilized in advance, then bottled and sealed, and sterilized at 60 ~ 70℃ 10 ~ 15 minutes. If sterilization is carried out before bottling, the liquor is quickly heated to 90℃ for one minute, and then bottled and sealed.