7th IDF International Symposium on Sheep, Goat and other Non-Cow MilkInternational audienceThe aim of this work was to identify key odorant compounds associated with main off-flavours (acid, rancid and faecal) and one defect related to the internal appearance (big irregular eyes) in ewes' raw milk commercial cheeses. Cheese samples were submitted to solvent assisted flavour evaporation (SAFE) and odorant compounds were detected by gas chromatography-olfactometry (GC-O). Odour-active compounds detected by GC-O were identified and quantified by gas chromatography-mass spectrometry (GC-MS). Partial least square regression was performed to determine relationships between relative abundances of the odour-active compounds and sensory defects of commercial cheeses. An imbalance in the concentration of short-chain free fatty acids, predominant compounds in all cheese samples, was associated with acid and rancid off-flavour, whereas faecal off-flavour was related to minor compounds such as 4-methylphenol and 3-methyl-1-butanol. No volatile compound could be related to the defect of big irregular eyes. (C) 2016 Elsevier Ltd. All rights reserved

Sensory quality is one of the most important attributes of cheeses, as consumers demand homogeneous and unaltered products. The presence of sensory defects in the final product causes financial losses and consequently has a great economic impact on cheese makers. Therefore, a study was conducted to find out main defects that affect sensory quality: eyes, paste, rind, flavour, texture and shape of commercial semi-hard ewe's raw milk cheeses. The frequency of occurrence of relevant sensory defects in cheeses with different ripening times and those manufactured in different seasons was also investigated. Samples were collected along 5 years during the annual sensory quality control from different cheese makers. Although flavour is a major determinant of consumer acceptance, most common defects were those related to the internal appearance, especially cracks, which were more frequent in summer cheeses, and caverns, which were more frequent in spring and winter cheeses. White paste, soft texture and acid flavour defects were more frequent in cheeses with shortripening period. Medium-and long-ripened cheeses presented a higher percentage of an excess of rind halo with a darker paste colour, animal flavour and marks in the rind. Due to compositional milk changes throughout cheesemaking seasons, cheese makers should adapt their manufacturing practises to those changes and try to achieve uniform cheeses. The results found in this study may be useful for the quality improvement of semi-hard ewe's raw milk cheeses.

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