Evaluation of Yeast Strains for Pomegranate Alcoholic Beverage Production: Effect on Physicochemical Characteristics, Antioxidant Activity, and Aroma Compounds

Abstract

In the present study, three commercial yeasts (for wine, beer, and cider) were evaluated for the production of pomegranate alcoholic beverage (PAB) from a juice of Wonderful variety. The physicochemical characteristics, antioxidant activity, and aromatic profiles of PABs were investigated before and after fermentation, while the effect of yeast strain and fermentation temperature (15 and 25 °C) was also evaluated. The PABs contained ethanol in the ranges of 5.6–7.0% v/v, in combination with glycerol (2.65–6.05 g L-1), and low volatile acidity. Total flavonoid content, total phenolic content, free radical-scavenging activity, and total monomeric anthocyanin content appeared to decrease after fermentation, possibly due to hydrolysis, oxidation, and other reactions. In general, PABs retained 81–91% of free radical-scavenging activity, 29–41% of phenolics, 24–55% of flavonoids, and 66–75% of anthocyanins. The use of different yeast affected mainly flavonoids and anthocyanins, and yeast strain M02 resulted in the highest values after fermentation. In PABs, 30 different volatile compounds were identified, specifically 15 esters, 4 organic acids, 8 alcohols, and 3 terpenes. The principal component analysis showed that the fermentation temperature affected significantly volatile composition, whereas, among the yeasts, WB06 is the one that seems to differentiate. The findings of this study show that the selection of the appropriate yeast and fermentation temperature is very crucial and affects the characteristics of the final product.

Impact of Sugar Type Addition and Fermentation Temperature on Pomegranate Alcoholic Beverage Production and Characteristics

“…Statistically, no significant effect was found in the case of final ethanol content. According to Kokkinomagoulos et al [10], the final ethanol content of PABs with no added sugars ranged between 6.8-7.0% v/v (using the same yeast and fermentation temperature), values evidently lower in comparison with those presented in Table 1. Similar levels for glycerol (a non-volatile alcohol that solely impacts taste and texture, elevating the levels of sweetness and fullness of the fermented beverage [20]) content (4.8-6.1 g L −1 ) were noted, and only in the case of CGJ addition the effect of temperature was significant (p < 0.05).…”

“…Reducing sugars (RS) were determined using the DNS (3,5-dinitrosalicylic acid) method [16] with some modifications, as described by Kokkinomagoulos et al [10]. Ethanol and glycerol contents were determined by means of HPLC, following the method described by Nikolaou et al [17].…”

“…Total flavonoids content (TFC), total phenolics content (TPC), free radical-scavenging activity (FRSA), and total monomeric anthocyanin content (TMAC) were determined as described in a previous study [10]. More specifically, TFC was determined by the flavonoidaluminum chloride (AlCl 3 ) complexation method and the results were expressed as mg of quercetin equivalents (QE) per liter.…”

“…Regarding fresh pomegranate fruit, literature data suggest that hexanal, limonene, 2-hexanal, and α-terpineol are the major aromatic compounds [8], while regarding pomegranate juice, studies suggest that 3-methyl butanal, ethyl butyrate, isopentyl acetate, hexanol, diethyl allyl malonate, and α-ionone are the respective major volatiles [9]. Studies about PABs and their aromatic profile are limited, with current reports indicating ethyl esters such as ethyl hexanoate, ethyl octanoate and ethyl decanoate, ethanol, 3-methyl-1-butanol, phenylethyl alcohol, and 3-methyl-1-butanol acetate, as the major aromatic compounds [10,11].…”

“…As far as PABs are concerned, relevant literature on the fermentation of pomegranate juice fortified with sugars is limited to sucrose [11]. Whereas, typically, the ethanol content of PABs using natural pomegranate juice ranges between 5.6-7.0 v/v, an increased ethanol content, up to 10%, is rather desired [10,15].…”