Tannin astringency, increasing

According to Lea (1992) the reaction between tannins and proteins depends on the degree of polymerization of the procyanidins. Astringency increases up to heptamer level and then decreases, as the molecules are too bulky. Maximum bitterness occurs with tetrameric procyanidins. These findings were confirmed by Mirabel (2000), showing that the difference between bitterness and astringency varied widely from one taster to another and that the distinction was not clear. 

Mannoproteins are complex hydrocolloids released from yeast cell walls during autolysis (Goncalves et al., 2002 Charpentier et al., 2004). According to Feuillat (2003), mannoproteins are important to wine quality as these contribute to protein and tartrate stability, interact with aroma compounds, decrease the astringency and bitterness of tannins, and increase the body of wine. For instance, Dupin et al. (2000) reported that mannoproteins prevent protein haze formation. Using a model wine. Lubbers et al. (1994) noted that yeast cell walls bound volatile aroma compounds, especially those more hydrophobic, and could potentially change the sensory characteristics of wines through losses of these aromas. 

Cinnamon is an ancient herbal medicine, long used to treat gastrointestinal disorders. It increases intestinal movement, heart rate, and perspiration by stimulating the vasomotor center. It improves circulation. The astringent tannins in cinnamon treat diarrhea the catechins treat nausea. Its essential oils are considered analgesic, antifungal, and germicidal. 

The lactic acid bacteria may cause polysaccharides to be released in a wine (Dols-Lafalgue et al. 2007). These compounds can increase the sensation of volume or body of wines, and can also be polymerized with the grape or wood tannins, reducing sensations of roughness or astringency, and producing more complex flavours. 

According to Noble and coworkers, seed tannins are perceived as rather bitter at low concentrations, but astringency takes over as the concentration increases (7,8). Otherwise, in apple ciders, hard tannin perception has been ascribed to bitterness (6). Nevertheless, in the Cabernet franc wines studied, low proanthocyanidin content appeared associated with soft tannins. Such discrepancy may be due to the particular composition of wine tannins, including prodelphinidins and various tannin-like structures e.g. oxidation products, ethyl-linked tannin polymers, anthocyanin-tannin adducts...), in addition to seed tannins. 

Tannins - Tannins promote inhibition of pathogenic miCTobial growth and reduce reproduction of viruses and bacteria. They also have astringent, tanning and hemostatic actions, and increase stability of capillary walls. 

Figures 8 and 9 show the results for Hiratanenashi and Jiro fruits, respectively. The growth curves of the fruits were double-sigmoidal in shape. The fruits of Hiratanenashi and Jiro reached harvest maturity in late October or the middle of November, respectively. In Hiratanenashi, the soluble tannin concentration in the flesh gradually declined during fruit development, and was about 1.0% when the fruit reached full maturity. In Jiro, the soluble tannin concentration decreased rapidly, starting in the middle of June, and the fruit became non-astringent in September. The amount of soluble tannins per fruit increased as the fruit developed and reached a maximum at the end of the second growth stage (slow enlargement phase) in both cultivars. The amount of soluble tannins that accumulated in Jiro fruit was much less than that in Hiratanenashi fruit.

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