Seasonal evolution of volatile compounds content and aromatic profile in milk and cheese from grazing goat

The objective of this study was to characterise the sensory profile of goat milk and cheese evaluated in three different seasons on the basis of alcohols, ketones, esters and terpenes content and profile. For this purpose, a trained panel of eight people was used, which sniffed the pure compounds corresponding to those found in all the products. One group of 15 lactating goats grazed a local pasture from March to July. Daily grazing time was approximately 8 h/day. During winter, spring and summer, herbage intake and the contribution of each species to the grazing diet were estimated by difference of herbage mass weight. Volatile organic compounds (VOC) content in herbage diet, milk and cheeses was determined by a multiple dynamic headspace extraction and GC-MS. The fragrance profile was described using the single pure compounds found in milk and cheese. The results showed that from winter to spring especially ketones content increased in milk, while no variation was observed for the other compounds. Summer milk was characterised mostly by terpenes. Also, the fragrance profile changed with grazing season. Winter milk was characterised by wood pulp-hay, green-herbaceous and blue-cheese notes, while in the spring by wood pulp-hay, blue-cheese, hot milk and musty. In the summer, the profile totally changed. In this season resinous, citrus, mint and fruity were the dominant notes. In comparison to herbage and milk, cheeses were less rich in volatile compounds. Not significant variation was observed in cheeses from a season to another, but their sensory profile was dominated by sweet odour. (c) 2005 Elsevier B.V. All rights reserved.