Press wines

For the home winemaker, the separation is facilitated if a cylindrical stainless steel screen closed at the bottom and long enough to extend from the top level of the cap to the bottom of the fermentation vessel is obtained. The screen is pushed down through the layer of skins until the screen bottom is in contact with the bottom of the fermenter. The wine is then siphoned from the inside of the screen into the containers in which the fermentation will finish. When no more free run wine can be obtained, the residual skins may be pressed to augment the yield considerably. Excessive pressure is to be avoided in this step lest the press wine be overly astringent and bitter. The free run wine should be kept separate from the press wine until the fermentations are finished. Tasting at this time will dictate whether the two can be blended without impairment of quality or whether the press wine is to be kept as a second quality wine. 

After the wine has been drained, the skins are pressed and usually the press wine is kept separate. The press wine is generally more tannic and of lower quality than the free-run. It often has higher flavor and frequently some or all of it may be blended into the free-run at a later date. 

After free draining, the pomace is removed and pressed. The press wine, which yields 30-45 gallons per ton, is dark red, high in tannin, and heavy bodied. This press wine generally is segregated from the free-run fraction and, after separate clarification to reduce the astringency caused by polyphenolic compounds, may be blended in with the main free-run volume. 

PRASIS or GREEN PRASIMUM - Flower of Copper PRESSORIUM — i.e., Press, Wine-press, etc,... 

Press wines are sometimes slightly brown due to higher levels of oxidized phenolics UF can remove these color bodies along with the slight bitterness from phenols. As a rule, UF appears to accentuate acidity and the lighter fruity elements while eliminating tannic-related "off notes". UF can also be used to increase the tannin content in red wines with poor body or mouth feel (tannin is retained by the membrane). 

Red press wine 100-150 Tannic red wine 75 Soft red wine 60 Rose wine 27-35... 

The total phenolics were higher in hot press compared to immediate press for wines from all varieties (Figure 2). Skin contact increased the phenolics relative to the hot press for Cabernet Sauvignon and Noble, but for Chambourcin there was slight decrease (p>0.05) in phenolics for skin contact compared to hot press wines. The total phenolics in 14 day wines were highest for Noble ( 1200 mg GAE/L compared to SOO mg GAE/L for the others). 

The results of the present studies showed that wines made from immediate press juices of the three varieties had the lowest total phenolics among all the treatments (Table 1). Heat treatment of the crushed grapes extracted phenols from the skins, but to a lesser extent than any of the hull treatments. In all varieties, hot press wines and juices were much higher in flavonoids and total phenolic content than immediate press wines and juices. The total phenolic concentrations of hot press wines and juices from Cabernet Sauvignon and Noble were shown to be lower than all the skin contact wines. However, for Chambourcin, hot press wine had the highest total phenol concentration among all treatments, and hot press juice had a similar phenol concentration to skin contact wines. 

For Cabernet Sauvignon, an interesting observation was that procyanidin B8 was present in immediate press wine at similar concentrations to those for skin contact wines, but low in immediate press juice. Procyanidin B3 and B4 were not detected in immediate press wine and juice. In hot press wine and juice, procyanidin B3 was present at lower amounts compared to all skin contact wines. However, hot press wine contained the highest amount of procyanidin B8 among all treatments. The amounts of catechin were low in both hot press wine and juice. 

In Chambourcin, immediate press wine and juice had low levels of catechin and procyanidin B3. Procyanidin B4 could not be quantified in both immediate and hot press wines and juices. The hot press wine had lower amounts of procyanidin B3 than skin contact wines, but the hot press juice had the highest amounts of B3 among all treatments. Catechin levels were the highest in hot press wine and juice compared to all other treatments. 

In Noble, immediate press wine and juice contained the lowest amounts of catechin, while both hot press wine and juice had the highest levels. A similar trend was observed for procyanidin B8, in which hot press wine also had the highest level. Procyanidin B3 was found in very low level in immediate and hot press wines and juices. 

The fermentation residue or pomace is processed into yeast-pressed wine or yeastbrandy, into wine oil (for brandy essence) and into tartaric acid. The left-over pomace is used as a feed or fertilizer. Pomace wine, obtained by fermenting a sugar solution containing the dispersed pressed-out pomace, is made only into a household drink and is not marketed. 

The role of pH has diverse practical consequences in the control of the malolactic fermentation. First of all, the malolactic fennentation is initiated more easily and rapidly in press wines than in the corresponding free run wine. A partial chemical deacidification of wine may be advisable in the most difficult cases. It is especially recommended in the preparation of a malolactic fermentation starter—used for the inoculation of recalcitrant wine tanks. Finally, particular attention must be paid to musts and wines with elevated pHs. They sustain a more or less anarchic bacterial growth of a large variety of bacteria and are thus subject to spoilage. A sensible sulfiting is the only tool for controlling these microorganisms. 

In white winemaking, excessive concentrations (>15 g/hl) followed by a significant sulfiting at the end of fermentation (>4 g/hl) can be a source of reduction odors and should be avoided. Press wines, however, should be more intensely sul-fited—especially in the case of continuous presses which cannot be disinfected regularly. 

In view of the fact that the high dose of SO2 required in any case to prevent oxidation also has antimicrobial effects, preventing malolactic fermentation in white wines is not usually a problem, except in wines with a high bacteria content and high pH, such as press wines. However, the use of lysozyme makes it possible to achieve the same protection with lower doses of SO2 (4-5 g/hl). It is necessary to add lysozyme either once (500 mg/1 in the must), or twice (250 mg/1 in the must and the same in the new wine), as one 250 mg/1 dose is not sufficiently effective. 

In red winemaking, these preparations are used in particular for press wines and heat-treated grapes and must. In the latter case, the must is very rich in pectic compounds and devoid of endogenous grape enzymes. These are destroyed by heat (Martiniere and Ribereau-Gayon, 1973). Pectolytic enzymes can also be used at the time of running off after a traditional maceration. 

All of the juice is fermented at the time of running-off, the press wine does not contain sugar. 

In conclusion, this feimentor design avoids alcohol loss by evaporation. Press wine quality is greatly increased, while the laborious work of cap punching is eliminated. This kind of tank has also been empirically observed to facilitate malolactic fermentation. 

The final stages of fermentation should be closely monitored. When the density drops below 1.000, this measurement is no longer sufficient to measure precisely the evolution of the fermentation. Moreover, the relationship between possible residual sugar and density is complex. When fermentation is complete, wine density can vary between 0.991 and 0.996, according to alcohol content. In addition, free-run wines always have a lower density than press wines, which are rich in extracted constituents. 

---