An Insight in Key Volatile Compounds in Goat Milk Based on their Odor Active Values
Author(s): Rita de Cássia R Egypto Queiroga, Maria Terezinha Santos Leite Neta, Rafael Donizete Dutra Sandes, Narendra Narain, Mércia de Sousa Galvão, Marta Suely Madruga, Roberto Germano
Goat milk is known to possess an off-flavor generally known as ‘goaty flavor’, which is not appreciated by consumers. Mostly the short-chain fatty acids are responsible for this undesirable sensory attribute. The objective of the present work was to identify the volatile compounds present in goat milk and to relate their impact on aroma characteristics. Volatile compounds from the milk were obtained by using a simultaneous distillation and extraction technique utilizing Likens and Nickerson’s apparatus. Two hundred milliliter of milk was used and extraction was carried out at 55°C for 120 min by using a mixture of pentane-ethyl ether (2:1) solvent. The extracts were concentrated and analyzed for the identification of volatile compounds using a system of high resolution gas chromatograph coupled with mass spectrometer. Better separation was achieved in a non-polar capillary column. A total of 91 volatile compounds were positively identified and these represented mostly the classes of compounds belonging to esters, aldehydes, alcohols, fatty acids, ketones and aromatics. The main compounds and their concentrations were hexanol (9481.92 µg/L), pentanoic acid (3040.08 µg/L), 2-pentanone (1651.03 µg/L), methyl 9-octadecenoate (1613.88 µg/L), methyl hexadecanoate (1060.61 µg/L) and 2-pentanol (1683.28 µg/L), while the compounds with their OAVs of 5 and higher that contribute in goat milk aroma were decanal (88), (E)-2-hexenal (72), hexanol (47), octanal (40), ethyl hexanoate (35), pentanal (34), nonanal (30), 2-pentanone (24), heptanal (23), methyl hexanoate (20), γ-dodecalactone (11), 2-heptanone (10), heptanol (9), ethyl octanoate (9), 2-pentadecanone (9), β-ionone (8), α-pinene (5), 2-methylthiophene (5), octadecanal (5).