In order to reduce the effect of factors other than the maceration treatments, grapes from the same vineyard were used. The overall ripeness of “Solaris” grapes in 2011 were at a good level with 21.1 ˝Brix in the direct pressed must. This density means that the wine has the potential to obtain an alcohol level considered optimal for a white wine style from a cool region as Denmark, being not too alcohol dominant while grapes were still ripe enough to have a good flavor potential. Details of pre-fermentation treatments are shown in Table 1. The pre-fermentative treatments WC and DP resulted in low levels of potassium, yeast assimilable nitrogen in the juice and low pH in the wine , in accordance with general oenology literature . CM treatment increased YAN from moderate in DP sample to high level in 6H_CM and 24H_CM samples. Additionally, CM increased pH but addition of SF during early fermentation did not result in any further pH increase . However, when measured in the young wine titratable acidity and especially tartaric acid levels were significantly influenced by thetime of skin contact. The lower tartaric acid levels and higher pH observed after 24H_CM + SF could be due to the higher potassium or other cations extracted from the grape skins during skin fermentation, which made further deacidification unnecessary in this wine. As deacidification has been shown to have no or very limited effect on the volatile profile of wine , grow bag for blueberry plants the acidity effects of the treatments were balanced by deacidification up to 2.50 g/L on the rest of experimental wines.
Table 3 shows that the later cold stabilization further reduced and stabilized acidity in the final wines. The levels of ethanol values ranged from 12.2% to 12.9% with a tendency of increasing levels after CM and SF. Additionally, the total polyphenol index was higher in the final wines with longer skin contact . The present result was in line with previous studies. Volatile acidity was generally low indicating a reductive and successful wine making process. In addition, the concentration of glycerol was around 6 g/L in all wines matching the level of alcohol produced by the yeast. The concentration is above the taste threshold level for glycerol and may, thus, positively contribute to the smoothness of the final wines. In total, 71 volatile compounds, comprising 35 esters, 16 alcohols, seven aldehydes, eight terpenes, two ketones, two sulfur compounds, and one C13-norisoprenoid, were quantified in the wines. Table 4 shows concentrations of volatile compounds and their sensory descriptions. Thresholds and odor activity values are also listed in the table. OAV allows estimation of the contribution of each volatile compound to wine aroma. It was determined by dividing the concentration by the odor threshold value of the compound reported in wine or matrix similar to wine, otherwise in water if not available in wine. To take the uncertainty of the calculated OAVs and the synergetic or additive impact of several volatile compounds into account, it was assumed that aroma compounds having an OAV of 0.1 or higher might be important in wine aroma. Esters are both synthesized by the grapes and arise from the alcoholic fermentation. Esters are important in wine flavor due to their pleasant fruity odor. In this work, esters represent the most abundant group of volatiles detected and quantified in the wines, and nine might contribute to wine aroma directly due to their relatively high OAVs .
CM and SF treatments had various impacts on the individual esters. Among nineteen identified ethyl esters, eight had OAV > 0.1 in all samples and among these, four were significantly influenced by the applied treatments. For example, the concentration of ethyl decanoate was significantly higher in 24H_CM wine than the rest of wines. Ethyl decanoate has been previously reported to provide fruity aroma to white wines. CM and SF pre-treatments did not enhance the formation of ethyl esters of branched acids, for instance, ethyl 2-methylpropanoate, ethyl 2-methylbutanoate, and ethyl 3-methylbutanoate. This could be due to the high concentrations of amino nitrogen in CM wines. Ethyl 3-methylbutanoate exhibited the highest OAV in WC wine. Ethyl 3-methylbutanoate has also been reported as an important odorant in Croatian “Rhine Riesling” wine. The acetate esters, generated by the reaction of acetyl-CoA with higher alcohols from degradation of amino acids or fatty acids, were generally not significantly affected by CM and SF treatments. Only three acetates had OAV > 0.1 and all of them were not affected by the treatments. However, a slightly higher concentration of acetates was observed in 24H_CM wine. Dennis et al.found that the content of an acetate ester increased with the pre-fermentation concentration of the corresponding precursor in a model must. Our results suggest a similar relationship between benzyl acetate and its precursor benzyl alcohol, as both increased in parallel in CM and SF wines . With respect to other esters , the amount of methyl hexanoate, methyl octanoate, methyl decanoate, and methyl salicylate increased by CM and SF treatments. However, these esters are most probably not important to the wine aroma as all of them were present at levels far below their individual odor thresholds. The influence of the maceration process on the concentration of esters depends on many factors, for instance, temperature, and grape cultivar and it is difficult to draw any general conclusions.
The amount of methyl octanoate was increased by CM treatment in this study, whereas the opposite effect was revealed in “Cabernet Sauvignon” wines. Alcohols are the second major group of volatile components in “Solaris” wines. Higher alcohols generally have characteristic pungent odor and give complexity to wine flavor, which in turn influences the character of wines. They are the main fermentation derived products by the yeast via sugar catabolism or decarboxylation and deamination of amino acids. As can be seen in Table 4, 3-methyl-1-butanol and 2-phenylethanol were by far the most predominant by amount among the 11 identified higher alcohols. Despite their very high concentrations, the sensory impact was minor due to high sensory thresholds. It should be noted that the quantification of 3-methyl-1-butanol is imprecise due to overloaded peaks. A high initial nitrogen concentration generally results in decreased production of higher alcohols related to amino acid production. In the present work, the amount of 2-methylpropanol, 1-propanol, and 2-phenylethanol decreased with increasing skin contact could be correlated the increased amount of YAN in the must with longer maceration . However, a significant increase of the amount of 2-phenylethanol was observed in 24H_CM + SF wines. One possible reason could be that extensive skin contact increased the availability of some amino acids contributing to the biosynthesis of 2-phenylethanol which occurs preferentially in berry skin as suggested by Slegers et al.. Nevertheless, its concentration was above threshold in all wines which might not relate to the sensory variations among studies wines. The concentration of benzyl alcohol increased significantly with the CM and SF treatments, this is likely to be due to an increased extraction of glycosylated precursors. C-6 compounds are originally present in crushed grape must, resulting from the enzymatic oxidation of grape polyunsaturated fatty acids through the lipoxygenase pathway. In this sense, unsurprisingly, WC wine contained the lowest content of C-6 alcohols . The 24 h CM generally favored the yield of C-6 alcohols in our study and this was in agreement with studies in “Albillo” and “Narince” wines, as well as “Chardonnay”, “Muscat” and “Cabernet Sauvignon” wines. In this study, however, these C-6 alcohols exhibited concentrations lower than their odor threshold, and therefore may not be sensed in the aroma of the macerated wines. Eight aldehydes and two ketones were detected in all wines, blueberry grow bag but most of them were not significantly affected by the treatments and the OAVs of these compounds were relatively low, except for 3-methylbutanal . Only hexanal and benzaldehyde showed significant changes as they increased in 24H_CM + SF wine, indicating skin fermentation enhanced the formation of these compounds. Hexanal can be produced from oxidation of 1-hexanol as discussed by Campo et al. or by enzymatic oxidation of C18 unsaturated fatty acids. Benzaldehyde, which has a bitter almond character, is considered a sensory important benzene compound in wine. In this study it was, however, found in a concentration much lower than the threshold . According to Paloma et al., shorter maceration had no significant effect on benzaldehyde in “Albillo” wine which is in agreement with our present study in 6H_CM wine. However, Vazquez et al. observed that maceration and enzyme treatment largely increased benzaldehyde. The higher level of benzaldehyde in the 6H_CM + SF and 24H_CM + SF wines probably related to the levels of benzyl alcohol in the wines . However, it can also originate from oxidation reactions by yeast on amino acids , glycoside precursors, phenol compounds of the grape, or from some secondary compounds like phenyl acetic acid and p-hydroxybenzoic acid. Terpenes are varietal compounds derived from the grapes where they often are found to be glycosidically-bound. They are usually associated with floral notes in wine aroma. In this study, eight terpenes, including terpene alcohols and some of their oxides, were identified in the wines.
Among them, linalool was dominating with the highest concentration and OAV in all wine samples. WC and DP wines had relatively low amount of linalool and hotrienol and their concentrations were below their thresholds. However, applied maceration caused an increase of these terpenes and this effect was more pronounced in skin fermented wines . A good example would be the level of linalool which was significantly increased by SF treatment and reached the highest odor activity levels in the 24H_CM + SF wine. Moreover, -β-ocimene and α-terpineol were significantly increased by SF but they had concentrations far below their thresholds. The presence of terpenes in wine is typically due to direct extraction of these compounds and the breakdown of glycoconjugates in the skin and in the solid parts of berry cells during the process of CM. In addition, some of these predominant monoterpenes, such as linalool, hotrienol, and α-terpineol can also be formed from geraniol during vinification. With regard to other compounds, two sulfur compounds -thiophenone and one C13-norisoprenoid were detected in all samples. Like some of the terpenes, the amount of β-damascenone was significantly increased by CM and SF treatments. This effect was in agreement with other studies. β-Damascenone can be formed by oxidative degradation of carotenoids during grape crushing, while a more probable source for damascenone in wine is acid-catalyzed rearrangement of C13 intermediates, with oxidation occurring in the grape during ripening.These precursors are, presumably, extracted to a greater extent during wine making. β-Damascenone is an important trace compound with very low perception threshold in wine and gives wines fruity and honey odor.Social animals constantly face conflicts of interest with other group members. In primates, decisions about different travel routes, group defense, or access to limited resources may result in divergent preferences for individuals and hence potential conflicts between group members. To resolve these conflicts, primates may engage in different sets of strategies including dominance, mutual cooperation or majority rules depending on factors such as group size and social organization. For instance, Lar gibbon females lead travel routes and access high value rewards before males despite the lack of a clear dominance of one sex over the other. In olive baboons instead, travel routes seem to be driven by majority rule despite their highly hierarchical social system. However, while these observations allow us to understand different aspects of primate behavior, it is often difficult to dissect the factors contributing to specific behavioral patterns in nature. Accordingly, experimentally controlled studies with primates can shed crucial light on the decision-making strategies underlying the observed behavior. To that end, over the last years numerous studies have adapted game theory models to explore the strategies that different primates use to overcome social dilemmas in which their interests come into conflict. For instance, computerized tasks have been used to present primate species including chimpanzees, capuchin monkeys and rhesus macaques with economic games borrowed from the game theory literature. These studies have found that, in general, primates can converge to a Nash Equilibrium during coordination and conflict games between days. Using a different approach, other researchers have presented great apes, mostly chimpanzees , with non-computerized social dilemmas in which apes had to decide between different physical actions to obtain rewards from an apparaThus.