Abstract: To investigate the correlation between the beany odor of raw cow’s milk and feed types, this study selected two samples of raw cow’s milk with beany odor and five common feeds: soybean meal, alfalfa, flaked corn, oat grass, and corn silage, and measured their volatile flavor compounds by headspace solid phase microextraction-gas chromatography-mass spectrometry (GC-MS). Key flavor compounds were identified using relative odor activity value (ROAV). The results indicated that acids and aldehydes contributed primarily to the beany odor of raw milk. A total of 49 volatile substances were identified in the two milk samples, among which hexanoic acid, octanoic acid, decanoic acid, decanal, nonanal, (E)-2-octenal, and (E)-2-decenal were the main beany odor substances. A total of 257 volatile substances were detected in all feed samples, including decanal, nonanal, and (E)-2-octenal. According to ROAV analysis, the beany odor compounds were more abundant in the feed samples than in the milk samples. The relative contents of beany odor compounds in the feed samples followed the following decreasing order of alfalfa > oat grass > soybean meal > flaked corn > corn silage, and flaked corn exclusively contained vanillin, with a strong milky aroma.

Key words: raw milk; beany flavor; feed type; headspace solid phase microextraction-gas chromatography-mass spectrometry; relative odor activity value

摘要： 为探究生牛乳产生豆腥味与饲料种类的相关性，选取2 个豆腥味生牛乳样本及5 种常见饲料（豆粕、苜蓿、压片玉米、燕麦草、玉米青贮），对其挥发性风味物质进行测定。基于顶空固相微萃取-气相色谱-质谱联用（gas chromatography-mass spectrometry，GC-MS）法测定挥发性物质组成，并结合相对气味活度值（relative odor activity value，ROAV）鉴定关键风味化合物。结果表明，酸醛类化合物是生牛乳产生豆腥味的主要原因。使用GC-MS从豆腥味生牛乳样本中共检出49 种挥发性物质，其中己酸、辛酸、癸酸、癸醛、壬醛、(E)-2-辛烯醛和(E)-2-癸烯醛是主要的豆腥味物质。对比所有饲料样本中检出的257 种挥发性物质，豆粕、苜蓿、燕麦草中的癸醛、壬醛、(E)-2-辛烯醛与牛乳豆腥味物质高度重合。经ROAV分析可知，饲料样本中的豆腥味化合物较豆腥味牛乳样本更为丰富，相对含量从高至低排序依次为苜蓿、燕麦草、豆粕、压片玉米、玉米青贮，而压片玉米中存在具有浓郁乳香味的香兰素。

关键词: 生牛乳；豆腥味；饲料种类；顶空固相微萃取-气相色谱-质谱；相对气味活度值