Aims: To study the population dynamics of indigenous malolactic bacteria in a Greek winery and to examine their potential to produce detrimental levels of biogenic amines (BA) under winemaking conditions.
Methods and Results: Although the wines studied were of different vintage, grape variety and enological characteristics, molecular typing of malolactic bacteria revealed only a low number of strains within the single‐species populations of Oenococcus oeni that developed during spontaneous fermentations. Strain MF1, originating primarily from the vineyards surrounding the winery invariably predominated in almost all samples. HPLC analysis showed a slight increase in the BA, putrescine, tyramine and phenylethylamine after malolactic conversion, while histamine, methylamine and ethylamine remained unaffected. No correlation could be established between the BA profiles and the bacterial compositions or the amino acid concentrations in wine samples studied.
Conclusions: A certain regional bacterial flora is established in the winery that prevails in spontaneous malolactic fermentations (MLF) irrespective of the wine characteristics. In all cases, the BA content of the wines after malolactic conversion was within enologically acceptable levels.
Significance and Impact of the Study: This is the first report on the malolactic bacteria occurring naturally in spontaneous MLF in Greek red wines and a preliminary assessment of their impact on wine safety in relation to BA.
β-Glucan, isolated from the mushroom Pleurotus ostreatus, at a concentration of 0.4%, was used in the manufacture of reduced-fat white-brined cheese from sheep milk. Control reduced-fat cheese was also produced from the same milk without the addition of β-glucan. The resultant cheeses were examined for their physicochemical characteristics, color and textural properties, and level of proteolysis and lipolysis. Furthermore, cheeses were evaluated organoleptically. In general, there were no statistical differences in the physicochemical characteristics and proteolysis levels found between both cheeses. The addition of β-glucan improved textural properties, and the cheeses received favorable grades for all the organoleptic characteristics. There were no flavor defects (such as a bitter taste) described by the panellists in this study. Generally, the addition of β-glucan did not significantly affect total free fatty acid content; however, at 180 days of ripening and storage, cheeses with the addition of β-glucan had a higher (p < 0.05) content than cheeses without β-glucan. The major fatty acids were acetic acid and capric acid.
In the present work, a fresh spreadable cheese from ovine milk with or without (control) fortification with β-glucan was manufactured. β-Glucan was extracted from the mushroom Pleurotus ostreatus and its concentration in the cheese was 0.4% (w/w). The composition, biochemical, and sensory properties of the cheeses during 21 days of storage were determined. At the end of storage, cheese fortified with beta-glucan had 75.26% moisture content, 10.30% fat, 1.71% salt, and 8.50% protein. Generally, the addition of β-glucan at this concentration did not significantly affect the composition, color, and viscosity measurements or the level of proteolysis and lipolysis and the antioxidant activity of the cheeses. However, cheese fortified with β-glucan showed a higher moisture content than control cheese on the 1st and 21st day of storage while the levels of proteolysis and the sensory properties of the cheeses were unaffected. During the sensory evaluation, panelists evaluated cheese with β-glucan with higher scores regarding the flavor characteristic compared to control cheese. The major free fatty acid was acetic acid in both cheeses and its concentration was higher in cheese with β-glucan. The results of the present study could be used by the dairy industry for manufacturing new products with improved health benefits.
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