Submitted to: Journal of Dairy Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/4/2007
Publication Date: 11/10/2007
Citation: Crossant, A.E., Washburn, S.P., Dean, L.L., Drake, M.A. 2007. Chemical properties and consumer perception of fluid milk from conventional and pasture-based production system. Journal of Dairy Science. 90:7456. DOI: 10.3168/jds.2007-0456. Interpretive Summary: Interpretive summary: Milk from pasture fed cows and cows fed with normal commercial feed were compared by sensory and chemical analysis. Consumers did not find any differences between the samples. The pasture fed cows produced milk that was lower in saturated fatty acids and higher in polyunsaturated fatty acids including isomers of conjugated linoleic acid, a fatty acid thought to have anticarcinogenic properties. This information says that milk from pasture fed cows is better nutritionally and that consumers will find it tastes the same as cows raised by feeding commercial feed.
Technical Abstract: Technical abstract: The continued popularity of organic and natural foods has generated interest in organic milk, and use of pasture for dairy cattle is a requirement for organic production. This process may improve the health benefits of fluid milk via increases in the unsaturated fatty acid content, including conjugated linoleic acid. Because pasture-based (PB) systems vary in types of forage, it is important to understand the impact of feed on the composition and flavor of fluid milk. The objectives of this study were to compare the chemical and sensory properties of PB milk with conventional fluid milk from Jersey and Holstein cows and to evaluate consumer acceptance of those milks. Fluid milk was collected throughout the 2006 growing season from Holstein and Jersey cows located in 2 herds: one fed a PB diet and one fed a conventional total mixed ration (TMR) diet. Milk was batch-pasteurized and homogenized. Sensory analyses, descriptive profiling, difference testing, and consumer testing were conducted on pasteurized products in separate sessions. Instrumental volatile analysis and fatty acid composition profiling were also conducted. The instrumental and sensory analyses differentiated the PB and TMR milks. Higher percentages of unsaturated fatty acids, including the 2 common isomers of conjugated linoleic acids, were measured in PB milks. Trained panelists documented higher intensities of grassy and cowy/barny flavors in PB milks compared with TMR milks when evaluated at 15ºC. Volatile compound analysis by solid-phase microextraction and gas chromatography-mass spectrometry separated PB and TMR milk samples. However, analyses showed no compounds unique to either sample. All identified compounds were common to both samples. Consumers were unable to consistently differentiate between PB and TMR milks when evaluated at 7ºC, and cow diet had no effect on overall consumer acceptance. These results indicate distinct flavor and compositional differences between TMR and PB milks, but the differences were such that they did not affect consumer acceptance. The current findings are useful to consider as interest in PB dairy production systems grows.