The Influence of Pasture and Non-pasture-Based Feeding Systems on the Aroma of Raw Bovine Milk

Abstract

Aroma-active compounds in raw bovine milk produced from cows fed perennial ryegrass (GRS) or total mixed ration (TMR) consisting of grass silage, maize silage, and concentrates were identified by direct immersion sorptive extraction (DI Hi-Sorb), coupled with gas-chromatography-mass spectrometry and olfactometry using odour intensity (OI) and aroma extraction dilution analysis (AEDA). Ninety-nine volatile organic compounds (VOC) were identified in these raw GRS and TMR milk samples; 33 of which were also present in the feed and rumen samples from these diets. Only the abundance of 13 VOC varied significantly based on diet. However, the odours of both raw milks were quite distinct as aroma perception is not influenced by abundance alone but also by the odour activity of each VOC. Approximately, 30% of the VOC influenced the aroma perception of these raw milks. This study clearly highlighted the significant impact of VOC transferring from the diet that influenced the aroma perception of both raw GRS and TMR milk. The aroma of the raw TMR milk was more complex than that of the raw GRS milk, and many of the key dietary-derived-odour-active VOC likely arose during the production of the TMR feed as most were either derived from Maillard reactions or impacted by heat. Seventeen of the 44 odour activities detected differed between both sample types. This study has clearly demonstrated the impact of diet on the aroma perception of raw bovine milk.

Quality and Functional Parameters of Fermented Milk Obtained from Goat Milk Fed with Broccoli and Artichoke Plant By-Products

“…Although diets are expected to greatly affect the aroma of milk, the fact that so little significant differences in volatiles could be linked to the different diets may be related to the previously reported observation that flavor complexity is highest when animals are fed a mixed ration including concentrates [ 56 ] as all diets included concentrates, besides, lactic acid culture is considered the main factor affecting the volatile profile of fermented milks [ 54 ].…”

Sensorial, cultural and volatile properties of milk, dairy powders, yoghurt and butter: A review

“…2018; Clarke et al. 2022). The impact of oxidation on VOC generation in milk and in many dairy products is significant, as the fatty acid profile of milk, especially PUFA is greatly impacted by diet (O'Callaghan et al.…”

“…Clarke et al. (2022) also used DI‐HiSorb (PDMS) at 40°C for 1 h to extract volatiles in raw milk and managed to successfully identify 99 VOCs consisting of acids (20), alcohols (17), aldehydes (16), esters & ethers (9), furans (3), hydrocarbons & benzenes (7), ketones (10), lactones (5), pyrazines & pyridines (4), sulphur VOC (3) and others (5).…”

“…Clarke et al. (2022) found that γ‐butyrolactone was an important odour active volatile in raw cow's milk, and that γ‐hexalactone influenced the aroma of cow's milk produced from a concentrate diet.…”

“…Key volatiles associated with the aroma of milk and dairy powders VOC including aldehydes, ketones, alcohols, lactones, phenols and esters in milk products originate from the degradation of the major milk constituents (lactose, citrate, milk lipids and milk proteins) (Cadwallader and Singh 2009), but many are also created through rumen metabolism can also be directly transferred from diet (Kilcawley et al 2018;Clarke et al 2022).…”