Mljekarstvo (Jan 2016)
The content of free fatty acids in relation to electronic nose sensors responses and sensory evaluation of cheese in a lamb skin sack (Sir iz mišine) throughout ripening
Abstract
The leading biochemical process during ripening of cheese in a lamb skin sack is lipolysis. In order to evaluate the influence of free fatty acids (FFA) liberated during lipolysis, on the cheese in a sack flavour and aroma, the relationship between sensory properties (odour, taste and total sensory score) and FFA content throughout ripening was determined. Additionally, differentiation of cheeses in various ripening stages was performed by analysis of specific profile of cheese volatile compounds using electronic nose. The obtained results demonstrated that the content of certain FFA is responsible for specific flavour and aroma in various ripening stages, which directly influence the consumers’ sensory scores of the cheese. The concentration of fatty acids C 14:0, C 14:1, C 17:0, C 18:0, C 18:2n-6 and C 23:0 (P<0.05), as well as C 16:0, C 18:3n-3, C 23:0 (P<0.01) in 45 days matured cheese resulted in significantly positive correlation with cheese odour. Concentrations of fatty acids C 8:0, C 17:0, C 18:0 C 18:1n-9t, C 18:1n-9c (P<0.05), C 14:0, C 16:0, C 16:1, C 18:3n-3, C 21:0, C 23:0 (P<0.01), C 12:0, and C 22:0 (P<0.001) correlated significantly with the cheese taste. As a consequence of the ripening time and the ripening conditions, C 4:0, C 6:0 and C 8:0 fatty acids were accumulated and contributed to the lower sensory scores of the 60 days matured cheese. Long-chain unsaturated FFAs ttC 18:2, C 20:2 and C 22:6n-3, also negatively correlated with the sensory properties of cheese in a sack, probably as precursors for synthesis of shorter acids and alcohols. Electronic nose analysis showed very well differentiation of cheeses in various ripening stages and these results are mostly in accordance with the results of consumers’ sensory assessment and physicochemical analyses. Well matured cheese was not well accepted by consumers due to the extensive lipolysis reactions in cheese during ripening. In terms of sensory quality electronic nose could be of a great help to cheesemakers in satisfying consumers requirements for optimal flavour and aroma properties of cheese by estimating ending of ripening time and lipolysis reactions.
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