Red wine, fermentation

The native grapes and their hybrids were generally easy to harvest and crush—at first by feet and later with roller crushers. Open wood tanks were used for red wine fermentations and closed tanks for whites. Eastern grapes are difficult to press because the skins slip from the pulp when pressed. Therefore, with the traditional hydraulic presses, it was difficult to secure a high juice yield. Various expedients were used rack-and-cloth presses, heating the skins and pulp before pressing, etc. See Figure 2. 

He reported red wine fermentations in the skins of five to eight days until fermentation is completed. He noted that the price of grapes depended on sugar content and that growers of ordinary varieties of high yield (10 tons) got almost as much per ton as growers of quality varieties growing on hillsides with low yield (2-A tons) 10.00 versus 12.00 per ton. 

Acetaldehyde plays an important role during red wine fermentation in which it can react directly with anthocyanins pigments to form vinyl adducts (pyroan-thocyanins) (Fulcrand et al. 1998), and can participate in the condensation of proanthocyanidins (tannins) and anthocyanins to form ethyl-bridge linked dimers... 

Asenstorfer, R. E., Markides, A. J., Hand, P. G., Jones, G. P. (2003) Formation of vitisin A during red wine fermentation and maturation. Australian Journal of Grape and Wine Research, 9, 40-46. 

Medina, K., Boido, E., Dellacassa, E., Carrau, F. (2005) Yeast interactions with anthocyanins during red wine fermentation. American Journal ofEnology and Viticulture, 56, 104-109. 

Morata, A., Gomez-Cordoves, M. C., Calderon, F, Suarez, J. A. (2006) Effects of pH, temperature and SO2 on the formation of pyranoanthocyanins during red wine fermentation with two species of Saccharomyces. International Journal of Food Microbiology, 106, 123-129. 

Wenzel, K. (1989) The selection of a yeast mutant to reduce color losses during red wine fermentation. Vitis, 28, 111-120. 

Du Toit, W J. and Lambrechts, M.G. 2002. The enumeration and identification of acetic acid bacteria from South African red wine fermentations. Int. J. Food Microbiol. 74, 57-64. 

Hilgard, E. W. The extraction of color and tannin during red-wine fermentation. Calif. Agric. Exper. Stat. Bull. 1887,77,1-3. 

The direct reaction between anthocyanins and hydroxycinnamic acids readily explains the formation of anthocyanin-vinylphenol-type adducts in red wines. At the time of writing, this is the only experimentally verified mechanism leading to the development of 4-vinylcatechol and 4-vinylsyringol pigments, as the free vinylphenols have neither been detected in wines nor was it possible to generate these compounds via enzymatic decarboxylation using yeasts commonly applied to red wine fermentation... 

Lactic Acid Bacteria. In the last several years, California winemakers have reported increased instances of stuck red wine fermentations attributed to prefermentation or early fermentative-phase growth of native lac-tobacilli (generally believed to be L. brevis). In these cases, acetic acid levels were extraordinarily high generally ranging from 0.8 to 1.5 g/L and, on occassion, 2 to 3 g/L (van der Water, 1996 personal communication). 

Although sulfite may not be as inhibitory to native yeasts as once believed, prefermentation additions are, nevertheless, crucial in the control of native lactic acid bacteria (LAB) and acetic acid bacteria (AAB). Failure to utilize the agent, at least in the recent history of some California red wine fermentations, has been one step implicated in rapid proliferation of spoilage LAB, the metabolites of which are strongly inhibitory toward both indigeneous and inoculated strains of Saccharomyces sp. (see Sec 1.4.1). 

Fermentation temperature plays an important role in establishing numerical superiority between Saccharomyces and non-Saccharomyces species. In red wine fermentations (68-86°F/20-30°C), Saccharomyces represents... 

As expected, fermentation rates by Saccharomyces 3xy viiih temperature. Ough (1964) reported that fermentations are relatively slow at 10 G/50 F compared with those conducted at 15°G/60°F or 27°G/80 F. Temperature also affects the population balance between Saccharomyces and non-Saccharomyces yeasts. In red wine fermentations (20°G/68°F to 30°G/86 F), Saccharomyces cerevisiae represents the dominant species (Sharf and Margalith, 1983), partially due to the warmer temperature of fermentation. At lower fermentation temperatures such as those used in white wine production, non-Saccharomyces yeasts can proliferate to yield much higher populations (Section 6.2.2). 

Baleiras Couto, M.M., R.G. Reizinho, and EL. Duarte. 2005. Partial 26S rDNA restriction analysis as a tool to characterize non-Saccharomyces yeasts present during red wine fermentations. Int.J. Food Microbiol. 102 49—56. 

Fig. 3.1. Example of daily fermentation monitoring in two tanks (initial must density = 1.085). (I) Normal fermentation curve after a latency period, fermentation initiates, accelerates and then slows before stopping on the 10th day at a density below 0.995, when all sugar is fermented. (II) Fermentation curve leading to a stuck fermentation fermentation stops on the 11th day at a density of 1.005 unfermented sugar remains. Fermentation slows early enough to take preventive action. (Ill) Evolution of the temperature (red wine fermentation) arrows indicate cooling...

Table 3.8. Stimulation of red wine fermentation by the addition of yeast hulls (maximum fermentation temperature of 34°C attained on day 7) (Lafon-Lafourcade et al., 1984)...

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