Effect of Flaxseed Supplementation in Diet of Dairy Cow on the Volatile Organic Compounds of Raw Milk by HS-GC–IMS

Abstract

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.

E-nose, E-tongue Combined with GC-IMS to Analyze the Influence of Key Additives during Processing on the Flavor of Infant Formula

“…The background is shown in white after subtracting the same components. However, red represents the higher concentration of the volatile component, and lower values are indicated by blue [ 27 , 28 ].…”

“…There were altogether 41 flavor compounds that were identified, including the monomer and its polymer, 12 aldehydes, 2 alcohols, 11 ketones, 9 esters, 4 olefins, 1 acid, and 2 furans. It was detected that one analyte might produce multiple signals, which included protonated monomers and proton-bound dimers or trimers [ 28 ]. IMS provided the second separation of compounds that was closely related to the high proton affinity or concentration of the compounds in the analytes [ 27 , 28 ].…”

“…It was detected that one analyte might produce multiple signals, which included protonated monomers and proton-bound dimers or trimers [ 28 ]. IMS provided the second separation of compounds that was closely related to the high proton affinity or concentration of the compounds in the analytes [ 27 , 28 ]. Some high concentration components were performed by both monomer and dimer forms, such as 2-heptanone, ethyl hexanoate, heptane, and beta-Pinene.…”

The composition of Tibetan kefir grain TKG-Y and the antibacterial potential and milk fermentation ability of S. warneri KYS-164 screened from TKG-Y

“…Esters are known to impart floral and fruity aromas to milk. 42 The formation of alcohol compounds in yogurt is related to reactions such as amino acid and lactose metabolism, methyl ketone reduction and fatty acid degradation, and all of these processes endow yogurt with floral, fruity and light wine aromas. 43 In yogurts, ketones are also produced by the conversion of carbon substrates through metabolic pathways of microorganisms; these give yogurt its unique aroma of caramel and cream.…”

Heterofermentative lactic acid bacteria such as Limosilactobacillus as a strong inhibitor of aldehyde compounds in plant-based milk alternatives

“…While saturated fatty acids are dominant in cow's milk, unsaturated fatty acids such as oleic acid (C18:1) and linoleic acid (C18:2, ω-6) are dominant in plant-based milk alternatives (Martínez-Padilla et al, 2020). It is known that unsaturated fatty acids can lead to the formation of aldehydes as secondary oxidation products, and some of these aldehydes are known to be compounds that cause off-flavors in cow's milk (Huang et al, 2022). Therefore, plant-based milk alternatives rich in unsaturated fatty acids need to require even more attention to off-flavor formation than the cow's milk.…”