Assessment of industrial lipases for flavour development in commercial Idiazabal(ewe's raw milk)cheese

摘要

Three commercial lipases(lipases A1 and A2 were pregastric lipases and lipase A3 was a fungal lipase)from three different manufacturers were studied to develop the characteristic pungent flavour of Idiazabal(sheep's raw milk)cheese in experimental productions(50 L vats),both in summer and in winter.In the experimental productions,all lipases significantly increased the concentration of total free fatty acids(FFA),both after 90 and 180 days of ripening.Lipases Al and A2 increased primarily the concentration of short-chain FFA(C4,C6 and C10),whereas C16:0 and C18:l were the main FFA obtained with lipase A3.Cheeses made with no lipase had the lowest concentrations of total FFA,with C16:0 and C16:1 as the major FFA.The percent of short-chain FFA was 70-80% of the total for lipases Al and A2,but 30-40% in cheeses made with lipase A3 or with no lipase.Sensory analysis was performed after 90 and 180 days of ripening.Cheeses made with lipases Al or A2 or with lamb rennet paste(which contains pregastric lipase and was used as control for sensory analysis)had significantly higher scores in 6 of the 22 attributes analyzed(odour and flavour intensity,sharp odour,pungent flavour and rennet odour and flavour)than cheeses made with lipase A3 or with no lipase added.Lipase Al was selected to conduct commercial cheese productions(200 L vats)made by artisan cheese makers adding 94 lipase units(LU)/50 L(high amount)or 8 LU/50 L(low amount).Control cheeses were made with lamb rennet paste having comparable amounts of lipolytic activity.After 90 and 180 days of ripening,cheeses made with the same amount of lipase(either as lipase Al or present in lamb rennet paste)were indistinguishable from each other,both from the sensory and analytical points of view(comparable amounts of total FFA,and percent FFA composition).Those with low amount of lipase were rated as 'mild',whereas those with high amount of lipase were rated as 'strong'.An industrial production(5000 L vat)with 100 LU/50 L yielded cheeses of 'intermediate strength' and intermediate levels of lipolysis.A linear correlation was observed between percent of short-chain FFA and the score for pungent flavour,for all amounts of lipase used in this study.We conclude that lipase A1 is an adequate commercial lipase to develop the characteristic flavour of Idiazabal cheese,both in artisan and industrial fabrications.