Huang Guoxin, Li Ning, Liu Kaizhen, Yang Jiyong, Zhao Shengguo, Zheng Nan, Zhou Jinhui, Zhang Yangdong, Wang Jiaqi
Key Laboratory of Quality and Safety Control for Milk and Dairy Products of Ministry of Agriculture and Rural Affairs, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China.
State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China.
Front Nutr. 2022 Feb 14;9:831178. doi: 10.3389/fnut.2022.831178. eCollection 2022.
Flaxseed supplementation in diet of dairy cow can effectively enhance the production of ω-3 polyunsaturated fatty acids (n-3 PUFA) in raw milk, which further give rise to the changes of volatile organic compounds (VOCs). In this study, we used headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) to investigate the VOCs in milk from cows fed three different diets (CK: supplemented with 0 g/d flaxseed; WF: 1,500 g/d whole flaxseed and GF: 1,500 g/d ground flaxseed). A total of 40 VOCs including three acids, six esters, 11 aldehydes, seven alcohols, 13 ketones were identified in all the raw milk samples. Compared with GF supplementation, suppling with WF could influence more compounds in raw milk (GF: five compounds; WF: 22 compounds). Supplementation with WF could increase the concentration of nonanal, heptanal, hexanal, which could cause the occurrence of off-flavors, and reduce the concentration of hexanoic acid (monomer; M), 2-hexanol, ethanol (M), 2-heptanone (dimer; D), 2-pentanone (M), 2-pentanone (D), acetoin (M) in raw milk. GF supplementation in diet could reduce the 2-pentanone (M), 2-pentanone (D). In addition, principal component analysis (PCA) based on the signal intensity of identified VOCs indicated that it is possible to distinguish between the CK and WF milk. However, GF milk could not be distinguished from CK milk. The results demonstrate that compared with GF milk, WF supplementation in diet of dairy cows could increase fishy (heptanal) cardboard-like (pentanal) flavor in milk and decrease sweet (hexanoic acid, 2-heptanone), fruity (ethyl butanoate, ethyl hexanoate, 2-heptanone) flavor which may lead the milk less acceptable. In conclusion, compared with WF, GF supplementation in diet of dairy cow showed higher increase in n-3 PUFA in raw milk, and less influence in VOCs of raw milk and this study might provide theoretical supports for the production of milk rich in n-3 PUFA.
在奶牛日粮中添加亚麻籽可有效提高原料乳中ω-3多不饱和脂肪酸（n-3 PUFA）的含量，进而引起挥发性有机化合物（VOCs）的变化。在本研究中，我们采用顶空气相色谱-离子迁移谱（HS-GC-IMS）对饲喂三种不同日粮（CK：添加0 g/d亚麻籽；WF：1500 g/d全亚麻籽；GF：1500 g/d磨碎亚麻籽）的奶牛所产牛奶中的VOCs进行了研究。在所有原料乳样品中总共鉴定出40种VOCs，包括三种酸、六种酯、11种醛、七种醇、13种酮。与添加GF相比，添加WF对原料乳中更多的化合物有影响（GF：5种化合物；WF：22种化合物）。添加WF会增加壬醛、庚醛、己醛的浓度，这些醛会导致异味的出现，并降低原料乳中己酸（单体；M）、2-己醇、乙醇（M）、2-庚酮（二聚体；D）、2-戊酮（M）、2-戊酮（D）、乙偶姻（M）的浓度。日粮中添加GF可降低2-戊酮（M）、2-戊酮（D）的浓度。此外，基于鉴定出的VOCs信号强度的主成分分析（PCA）表明，有可能区分CK牛奶和WF牛奶。然而，GF牛奶与CK牛奶无法区分。结果表明，与GF牛奶相比，奶牛日粮中添加WF会增加牛奶中的鱼腥味（庚醛）、纸板样气味（戊醛），并降低甜味（己酸、2-庚酮）、果香味（丁酸乙酯、己酸乙酯、2-庚酮），这可能会使牛奶的可接受性降低。总之，与WF相比，奶牛日粮中添加GF使原料乳中n-3 PUFA的增加幅度更大，对原料乳中VOCs的影响更小，本研究可能为生产富含n-3 PUFA的牛奶提供理论支持。
