First, the variety and maturity of grape raw materials
There are many varieties of grapes used in the production of red wine, which have a deep color, such as Cabernet Sauvignon, Pinot Noir; there are light-colored, such as Cabernet Franc, Rosé, etc. Sometimes the grape growers mix Cabernet Sauvignon into the wine, and even send it to the winery for sale. Sometimes winegrowers to Cabernet Franc, or even Rosemary mixed into Cabernet Sauvignon together to the winery sales, some wineries were confused, some wineries test out, but can only be purchased at a reduced price, with this raw material brewed out of the original color of the grapes is undoubtedly shallow wine. The other side of the coin is the ripeness of the raw grapes. Grape berries from the seat of the beginning to full maturity, need to go through the history of young fruit period, color change period, ripening period, ripening period and other four stages. During the ripening period, the grapes reach the intrinsic size and color of the variety, the acid content decreases rapidly and the sugar content rises, this period lasts for about 35-50 days, and it is only at the end of this period that the grapes can fully ripen. For red winemaking grapes should be harvested when the grapes are fully ripe, i.e., when the pigment content is the highest but the acidity is not too low.
Second, the influence of yeast on the color of red wine
Alcoholic fermentation is the process by which yeast converts the sugar in the grape berries into alcohol and CO2 gas. Winemaking can be done with natural yeast fermentation, strain expanded culture fermentation, and active dry yeast fermentation. Active dry yeast has gradually replaced the first two types due to the advantages of ease of use, fast start-up of fermentation, low by-products, and thorough fermentation, and has been favored by more and more manufacturers in China. At present, there are many kinds of active dry yeasts used by domestic wineries, including domestic Angie's yeast, Spanish Agrovin yeast and active dry yeast of LALLEMAND, and the classification is very fine, with special yeasts for red wine, dry white wine, sparkling wine, and so on. Taking the active dry yeast of Lallmand as an example, there are D254, RA17, BM45, RC212 and so on for dry red wine. Each different type of yeast brewed grape wine color varies greatly.
Third, the influence of winemaking equipment on the color of red wine
Wine fermentation containers include cement pools, carbon steel tanks, oak barrels, vertical fermentation tanks and rotating tanks. The rotating tank has a heating and cooling system that can control the maceration temperature, and has a certain pressure retention capacity, when the pressure in the fermentation tank reaches a certain level before starting to exhaust, the carbon dioxide produced when the fermentation is just starting to cover the upper surface of the grape berries in the tank, which plays a role in preventing oxidization, but also carbon dioxide impregnation effect. Rotating tank can be set tank rotation interval time and forward and reverse rotation laps, grape berries in the rotating tank rotating at regular intervals, so that the skin residue, sweat fully uniform, conducive to pigment maceration.
Fourth, the impact of the number of times of pouring on the color of red wine.
Vertical stainless steel tank fermentation of red wine, during the alcoholic fermentation, pouring method, pouring time and pouring number of tanks is crucial, is a reflection of the level of winemaker one of the key process points. Pouring is commonly known as playing the cycle, that is, the bottom of the fermentation tank of grape juice pumped to the upper part of the fermentation tank, divided into open pouring tank and closed pouring tank. Open pouring tank will be from the bottom of the tank outlet into the middle container, and then pumped to the top of the tank; closed pouring tank is directly to the pump inlet to the bottom of the tank outlet, pumped directly into the top of the tank to rinse the skin residue. The main functions of pouring tank are: (1) to make the fermentation base, including the addition of raw and auxiliary materials fully mixed; (2) pressure cap to prevent the drying of the dregs, and to promote the exchange of substances between the liquid phase and the solid phase; (3) to make the fermentation substrate ventilated to provide oxygen conducive to the activities of yeast, and to avoid the reduction of SO2 to H2S. Sulfite, yeast, sugar, it is believed that the main role of the pouring tank is only to mix the fermentation substrate. But this is far from enough, because with the alcoholic fermentation, grape pomace due to the specific gravity of light, on the other hand, due to the fermentation of rising CO2 gas, so that pomace rise, in the tank on the surface of the grape juice to form a thick layer, commonly known as the "cap", which results in the drying of the pomace on top of the juice and isolation, and pomace in the connection with the juice at the Juice in contact with the pomace to form a saturated layer, is not conducive to the leaching effect, then it is necessary to use the inverted tank to wash the entire surface of the pomace to destroy the formation of the saturated layer, so that it is conducive to the extraction of flower pigments, tannins and other leaching.
Generally, in dry red wine throughout the alcoholic fermentation process, need to carry out three open pouring, the first time in the addition of pectinase, active dry yeast, pouring tank volume of about 1/20 of the tank volume; the second open fermentation has just started, pouring tank volume of about 1/5 of the tank volume; the third time can be carried out in the addition of sugar, pouring tank volume of about 1/10 of the tank volume. Closed decanting, the first closed decanting can be carried out after the grapes are fed into the full tank, and its main purpose is to fully mix the SO2 added at the time of feeding. The rest of the time, can be carried out once a day closed-type pouring, each time to pour the tank volume of 1/5 or 2 times a day closed-type pouring, each time to pour the tank volume of 1/10, the main purpose is to mix the base of the fermentation and drenching skin residue, destruction of the saturated layer, to enhance the pigment leaching.
Fifth, the effect of separation time on the color of the original red wine.
During the fermentation of red wine, there is no accurate time and number of days for the separation of pomace, which is closely related to the quality of grape raw materials, the time of the start of alcoholic fermentation, the speed of fermentation, the temperature of the fermentation, and the type of wine required to be produced. Some wineries use the number of days of maceration and fermentation to determine the time of separation, others use the specific gravity of the wine to determine whether it should be separated or not, and some wineries directly separate the grape skins at the end of fermentation. At the beginning of alcoholic fermentation, the anthocyanins, tannins and aromatic substances in the grape skins are continuously extracted, but when the color of the wine reaches a certain level, the anthocyanin content of the wine no longer rises and the color of the wine no longer deepens. If the pomace of the grape skins is not separated and continues to be macerated at this time, the pomace of the grape skins will adsorb a part of the pigment in the wine, making the wine lighter in color, and the content of the tannins in the wine will rise with the prolongation of the maceration. The tannin content of the wine rises as the maceration time increases. Therefore, if you want to produce wines with deep color, strong fruity aroma, soft body and high tannin content for 2-3 years, you should shorten the maceration time, generally 5-6 days after the start of alcoholic fermentation, and separate the pomace in 10-15 days, the best way is to observe and compare with the naked eye, and determine the absorbance value at 520mm with a spectrophotometer, and then separate the pomace when the pigment in the wine reaches the highest value, the fermentation temperature should be controlled at 25-27%, and the pomace should be separated at 520mm. The fermentation temperature is controlled at 25-27℃. On the contrary, in order to obtain the wine to be aged for a long time, the maceration time should be extended, if the maturity and quality of the raw materials of the grapes are good, the skins can be separated directly in the suspension of alcoholic fermentation, so that the wine is rich in tannin, with a strong sense of structure, and the fermentation temperature can be controlled in the range of 27-30 ℃.
Wanting a darker colored dry red wine, it is recommended to start from the following aspects:
1, select the darker colored grape varieties, control the maturity of the grapes, let the grapes fully ripe, in the highest pigmentation in the berries and acid content is not too low, and in addition to the stalks and crushing of the pre-exhaustion of a process of sorting, eliminating the lack of ripening of the raw green fruits, rotting fruit, and so on.
2, the selection of appropriate yeast strains, preferably dry red special and conducive to the extraction of pigment tannins, aromatic substances and other yeast strains.
3, reasonable and appropriate use of enzyme preparations, so that is conducive to maceration.
4, the rapid start of alcoholic fermentation, and the reasonable use of SO2, to prevent the oxidation of grape berry pigments.
5, more beating cycle during fermentation, in general, can be 1-2 times a day closed beating cycle to wash the skin pomace, the amount of treatment depending on the specific circumstances.
6, the fermentation temperature can be controlled in the range of 25-28 ℃, too low is not conducive to maceration, the temperature is too high will make the wine body rough, more by-products.
7, accurately grasp the time of separation of the skin and residue, when the highest pigment content of the body of the wine is the darkest color when the rapid transfer of tank separation, pure juice fermentation.
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