Analysis on the production principle of fruit wine
Fruit wine is produced by using fresh fruits as raw materials, using wild or artificially added yeast to break down sugar and produce alcohol and other by-products. Along with the production of alcohol and by-products, a series of complex biochemical reactions occur inside the wine, which ultimately gives the wine a unique flavor and color. In order to achieve the production of high-quality fruit wine in production, the following main components need to be analyzed as the basis for testing the quality.
1 alcohol: wine
Fine energy can prevent the destruction of wine by microorganisms (mixed bacteria) and has a certain effect on ensuring the quality of wine. Therefore, the alcohol content of fruit wine is mostly at 12-24 degrees.
2 Acid: The acid in the wine is brought by raw materials, such as tartaric acid in grapes, malic acid in apples, citric acid in bayberry, etc.; also produced during fermentation, such as acetic acid, butyric acid, lactic acid, succinic acid, etc. . If the acid content of the wine is appropriate, the taste of the wine will be mellow, harmonious and palatable. The opposite is worse. At the same time, acid also has a certain effect on preventing the proliferation of bacteria. The indicators used in production to indicate the acid content of fruit wine are total acid and volatile acid. The total acid, that is, the total content of the acidic reaction substance, has a great relationship with the flavor of the wine (the total acid amount of the wine is generally 0.5-0.8 g / 100 ml). Volatile acid refers to some acids that evaporate with water vapor. In practice, acetic acid is calculated (the volatile acid in wine should not be higher than 0.15 g/100 ml).
3 Sugar: Due to the variety of fruit wines and the hobbies of people everywhere, the demand for sugar in wine is extremely different. China generally requires between 9-18% sugar.
4 Tannin: If there is a lack of tannin in the wine, the taste of the wine will be dull; if the content is too high, the wine will be bun. The general requirement is that the tannin content in light-colored wine is 0.1-0.4 g/L, and in dark wine it is 1-3 g/L.
5 Pigments: Fruit wines have different colors because they contain different pigments. The pigment in the wine darkens or precipitates due to oxidation as the storage time increases. This is because the wine is not as fresh as the new wine.
6 Leachate: The residue obtained after the fruit wine was heated and evaporated at 100 ° C. There are mainly glycerin, non-volatile acids, proteins, pigments, esters, minerals and the like. The leachate of our country's general red wine is between 2.7-3 g / 100 ml, and the white wine is 1.5-2 g / 100 ml. If the extract is too low, the wine will be dull.
7 total sulfur dioxide and free sulfur dioxide: is the fruit wine left over from the production process. It is generally stipulated that the total sulphur dioxide content in the liquor should not exceed 250 ml/l; the free sulphur dioxide should not exceed 20 ml/l.
8 heavy metals: The general rule is: iron should not be higher than 8 ml / liter; copper should not be higher than 1 ml / liter; aluminum should not be higher than 0.4 ml / liter.
Among the wines, wine is a worldwide product, and its production, consumption and trade volume rank first. Followed by cider, it is more common in the United Kingdom, France, Switzerland and other countries, the United States and China also brew. There are citrus wine, jujube wine, pear wine, arbutus wine, persimmon wine, thorn pear wine, etc. They are not strict in the selection of raw materials, and there is no special brewing variety, as long as the sugar content is high, the flesh is dense, the aroma Rich and fruity fruits can be used for wine making.
(1) Process of fruit wine brewing
Fresh fruit→Sorting→Crushing, de-stalking→fruit pulp→separating juice→clarification→clear juice→fermentation→pouring barrel→storage→filtration→cold treatment→dispatching→filtering→finished product
(2) Process brief
Pre-fermentation treatment: Pre-treatment includes fruit sorting, crushing, pressing, clarification of juice, and improvement of juice.
Broken, de-stalking: Breaking requires each seed to rupture, but the seeds and fruit stalks cannot be broken, otherwise the oil esters, glycosides and some substances in the stalks in the seeds will increase the bitterness of the wine. The crushed pulp immediately separates the pulp from the fruit stems, preventing the grassy taste and bitter substances in the fruit stems from being dissolved. The crusher has a double roll crusher, a drum scraper, a centrifugal crusher, a hammer crusher and the like.
Separation of slag juice: The juice that flows out without pressure after being crushed is called self-flowing juice, and the juice that flows out after pressurization is called squeezed juice. The quality of the self-flowing juice is good, and the high-quality wine should be prepared separately. The pressing is carried out twice, and the first time the pressure is gradually applied, and the juice in the pulp is pressed out as much as possible. The quality is slightly poor, and it should be brewed separately or combined with the self-flowing juice. Loosen the residue, add water or not, for the second press, the pressed juice is heavy, low quality, suitable for distilled liquor or other purposes. The equipment is typically a continuous screw press.
Clarification of fruit juice: Some insoluble substances in the pressed juice will produce adverse effects in the fermentation, which will bring odor to the wine. Moreover, the fruit wine obtained by using the clarified juice has high stability, is not sensitive to the action of oxygen, and has a light color. Low iron content, stable aroma, and refreshing wine. For clarification, please refer to the clarification of the juice.
Sulfur dioxide treatment: The role of sulfur dioxide in fruit wine is sterilization, clarification, anti-oxidation, acidification, dissolution and reduction of pigments and tannins, and the flavor of wine is improved. The use of sulfur dioxide is gaseous sulfur dioxide and sulfite, the former can be directly passed through the pipeline, while the latter is dissolved in water and added. The concentration of sulfur dioxide in the fermentation substrate is 60-100 mg/L. In addition, the following factors need to be considered: when the raw material contains high sugar, the chance of sulfur dioxide binding increases, and the dosage is slightly increased; when the acid content of the raw material is high, the active sulfur dioxide content is high, the dosage is slightly reduced; the temperature is high, easy to be combined and volatile, The dosage is slightly reduced; the higher the microbial content and activity, the more complicated, the higher the dosage; the mildew is severe and the dosage is increased.
Juice adjustment:
1 Sugar adjustment: brewing alcohol with 10%-12% alcohol content, the sugar content of the juice needs 17-20 °Bx. If the sugar content does not meet the requirements, sugar is needed. In actual processing, sucrose or concentrated juice is commonly used.
2 Acid adjustment: acid can inhibit the growth of bacteria, make the fermentation go smoothly; make the red wine bright color; make the wine taste fresh and soft, and produce ester with alcohol to increase the aroma of the wine; increase the storage and stability of the wine . Dry wine is easy to be 0.6%-0.8%, sweet wine 0.8%-1%, general pH is greater than 3.6 or titratable acid is less than 0.65%. Acid should be added to the juice.
Alcohol fermentation:
1 Preparation of wine master: The wine mother is added to the fermented yeast after the expansion, and the production needs to be expanded three times before it can be added. It is called first-stage culture (test tube or flask culture), secondary culture, tertiary culture, and finally Cultivate in a jug. Methods as below:
Primary culture: About 10 days before the production, the fruit is ripe and not deteriorated, and the juice is pressed. Load into clean, dry heat sterilized tubes or flasks. The amount of the test tube is 1/4, and the volume of the triangular flask is 1/2. After being filled, it was sterilized by boiling water at normal pressure for 1 hour or 58 kPa for 30 minutes. After cooling, the culture strain is connected, and the juice is shaken to disperse. The culture is carried out, and when the fermentation is vigorous, it can be cultured in the lower stage.
Secondary culture: 1/2 juice is placed in a clean, dry heat-sterilized triangular flask, and the above culture solution is added for cultivation.
Three-stage culture: Select a clean and disinfected large glass bottle of about 10L, and add the juice to the fermented plug to add about 70% of the volume. Heat sterilization or sterilization with sulfurous acid, the latter should contain 150mg of SO2 per liter of juice, but it needs to be placed for one day. The bottle mouth is disinfected with 70% alcohol, and the second strain is connected to the second strain. The dosage is 2%, and it is cultured in the incubator. After vigorous breeding, it is expanded.
Jellyfish barrel culture: After disinfecting the wine jug with SO2, it is filled with 12-14oBx juice and cultured at 28-30 °C for 1-2 days to produce the wine. The cultured wine master can be directly added to the fermentation broth in an amount of 2% to 10%.
2 Fermentation equipment: The fermentation equipment should be able to control temperature, easy to wash, drain, and ventilate well. It should be cleaned before use and fumigation with SO2 or formaldehyde. The fermentation vessel can also be used for both fermentation and storage, requiring no leakage, can be sealed, and does not chemically interact with the liquor. There are fermenters, fermentation tanks, and special fermentation equipment, such as rotary fermenters, automatic continuous cycle fermenters.
Fruit juice fermentation: fermentation is divided into main (pre) fermentation and post-fermentation. During the main fermentation, the juice is put into the container, the amount is 4/5 of the volume of the container, then 3%-5% of the yeast is added, and the mixture is evenly stirred. Controlled at 20-28 ° C, the fermentation time varies with the activity of the yeast and the fermentation temperature, generally about 3 to 12 days. When the residual sugar is reduced to 0.4% or less, the main fermentation ends. Then, post-fermentation should be carried out, that is, the wine container is sealed and transferred to the wine kiln, and left at 12-28 ° C for about 1 month. Clarification is carried out after the end of the fermentation, and the clarification method is the same as the juice.
Finished product blending: The blending of fruit wine is mainly blended and adjusted. The blending is the blending of the choice of the original wine with the appropriate ratio; the adjustment is to adjust certain components of the blended wine according to the product quality standards. For blending, generally choose a raw wine with a quality close to the standard as the base raw wine. According to its shortcomings, one or several other wines are selected as the blending wine, and a certain proportion is added for sensory and chemical analysis to determine the proportion. Adjustments, mainly indicators of alcohol content, sugar, acid and so on. The adjustment of alcohol content is best to use the same type of alcohol with high alcohol content, or add distilled liquor or alcohol; if the sweet wine contains insufficient sugar, the best effect is to use the same type of concentrated juice, and sugar can also be used, depending on the quality of the product. Depending on the acid;
Filtration, sterilization, bottling: filtration with diatomaceous earth filtration, thin plate filtration, microporous membrane filtration, and the like. Fruit wine is usually packed in glass bottles. When bottling, empty bottles are immersed in 2-4% lye at a temperature above 50 °C, cleaned, drained and sterilized. Fruit wine can be pasteurized and then bottled or cold-packed. Alcohol with low alcohol content should be sterilized after bottling.