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J Dairy Sci

Title:		The volatile organic compound profile of ripened cheese is influenced by crude protein shortage and conjugated linoleic acid supplementation in the cow's diet
Author(s):		Ni Q; Gasperi F; Aprea E; Betta E; Bergamaschi M; Tagliapietra F; Schiavon S; Bittante G;
Address:		"Department of Agronomy, Food, Natural Resources, Animals and the Environment (DAFNAE), University of Padua, Viale dell'Universita 16, 35020 Legnaro (PD), Italy. Department of Food Quality and Nutrition, Research and Innovation Centre, Fondazione Edmund Mach (FEM), Via E. Mach 1, 38010 San Michele all'Adige (TN), Italy. Department of Agronomy, Food, Natural Resources, Animals and the Environment (DAFNAE), University of Padua, Viale dell'Universita 16, 35020 Legnaro (PD), Italy. Electronic address: franco.tagliapietra@unipd.it"
Journal Title:		J Dairy Sci
Year:		2020
Volume:		20191127
Issue:		2
Page Number:		1377 - 1390
DOI:		10.3168/jds.2019-16495
ISSN/ISBN:		1525-3198 (Electronic) 0022-0302 (Linking)
Abstract:		"A shortage in crude protein (CP) and supplementation of conjugated linoleic acids (CLA) in the diets of dairy cows could improve the dairy industry's ecological footprint and the nutritional value of milk, but it is not known what effect such a strategy might have on the aroma profiles of dairy products. The aim of this work was to study the effects of reducing the dietary CP content (from 150 to 123 g/kg of dry matter), with or without a supply of rumen-protected CLA (7.9 g/d C18:2 cis-9,trans-11 and 7.7 g/d C18:2 trans-10,cis-12), on the volatile organic compound (VOC) profile of cheeses ripened for 3 mo. Twenty mid-lactation Holstein-Friesian cows were reared in 4 pens (5 to a pen), and fed 4 different experimental diets over 4 periods of 3 wk each, following a 4 x 4 Latin square design. Twice in each period, 10-L milk samples were taken from each group and used to produce 32 cheeses, which we then analyzed for VOC by solid-phase microextraction and gas chromatography-mass spectrometry. We detected 48 VOC belonging to 10 chemical classes (11 alcohols, 8 ketones, 8 esters, 7 acids, 4 aldehydes, 4 sulfurs, 2 lactones, 2 phenolic, 1 monoterpene, 1 hydrocarbon); these were expressed as concentrations in cheese (quantitative data) or as proportions of total VOC (qualitative data). The results of mixed model analysis showed that the majority of VOC families and individual VOC in ripened cheese were affected by the dietary treatments: CP shortage depressed the concentrations of volatile aldehydes and increased the proportions of some esters and limonene, whereas CLA increased the concentration of total VOC, particularly several acids and esters, and decreased the proportions of ketones and phenolic compounds. The interaction between dietary CP and CLA affected the proportions of alcohols and acids. We performed a factor analysis to extract 5 latent explanatory variables from the individual VOC, which represented 79% of total VOC variance for the quantitative data and 78% for the qualitative data. Addition of CLA decreased the first qualitative factor (the 'base aroma' of cheese, explaining 44% of total variance), whereas CP reduction increased the second quantitative factor ('ethyl esters,' 15% of total variance) and the third qualitative factor ('butan-,' 9% of total variance). In summary, the VOC profile of ripened cheese was heavily influenced by CP content and CLA supplementation in the diets of dairy cows, but the effect on sensorial properties of cheese is also worth considering"
Keywords:		"Animal Feed/analysis Animals Cattle/*physiology Cheese/*analysis Dairying Diet/veterinary Dietary Proteins/analysis Dietary Supplements/*analysis Female Gas Chromatography-Mass Spectrometry/veterinary Lactation Linoleic Acids, Conjugated/*analysis Milk/*c;Animals;"
Notes:		"MedlineNi, Qianlin Gasperi, Flavia Aprea, Eugenio Betta, Emanuela Bergamaschi, Matteo Tagliapietra, Franco Schiavon, Stefano Bittante, Giovanni eng 2019/12/02 J Dairy Sci. 2020 Feb; 103(2):1377-1390. doi: 10.3168/jds.2019-16495. Epub 2019 Nov 27"