Soft goats’ cheese enriched with polyunsaturated fatty acids by dietary supplementation: manufacture, physicochemical and sensory characterisation

Abstract

Modifying the lipid composition of milk and dairy products, to improve their nutritional properties, without negatively altering their technological, sensorial and functional qualities, constitutes a challenge for the dairy sector. This study was performed to increase the polyunsaturated fatty acids (PUFA) and decrease the saturated fatty acids (SFA) content of goats’ milk, under real field conditions and production, by means of altering the animals diet. The effect of these changes were characterised during the manufacture of soft ripened cheese and assessing the impact on physicochemical and sensorial characteristics. Two groups of 30 crossbreed Alpine dairy goats were fed either a control diet or a diet supplemented with oilseeds providing 50.4 g UFA.goat⁻¹.day⁻¹ or 69.6 g UFA.goat⁻¹.day⁻¹ which supplied respectively 1.4 and 2.4 % of alpha-linolenic acid (ALA). Supplementing the feed of dairy goats with PUFA was shown to have beneficial effects on the FA composition of goat’s milks and cheeses: (1) an increase in the content of ALA (18:3n-3; from 0.78 to 1.78 g.100 g⁻¹ of total FA) and rumenic acid (main CLA; from 0.75 to 1.27 g.100 g⁻¹ of total FA); (2) a decrease in the n-6/n-3 PUFA ratio (from 4.6 to 2) and the overall SFA content (from 66 to 60.4 g.100 g⁻¹ of total FA). The corrected cheese yield was higher for the supplemented milks (16.3 %) in comparison to the control milks (15.4 %). Both cheeses showed a similar evolution in the levels of proteolysis and lipolysis with no flavour defects being detected. Cheese sensory scores for the two types of cheeses were similar. Hence, healthier goats’ milk and cheese FA profiles were obtained with good sensorial characteristics.

摘要 :

调整乳和乳制品中脂质组成,提高其营养特性,并保持乳制品的加工、感官和功能特性是当今的研究热点。本研究是在保持生产工艺不变的前提下,通过改变动物饲料的组成,以增加山羊奶中多不饱和脂肪酸含量和减少饱和脂肪酸的含量,并评价饲料组成变化对软质成熟干酪的物化和感官特性的影响。将30只杂交的阿尔卑斯奶山羊分成两组:一组为对照组,另一组每天每只山羊提供含50.4g不饱和脂肪酸的油菜籽和1.4%的α-亚麻酸(ALA),或者提供含69.6g不饱和脂肪酸的油菜籽和2.4%的α-亚麻酸。饲料中多不饱和脂肪酸含量显著地影响羊奶和羊奶干酪的脂肪酸组成:(1)ALA(18:3n-3)的含量从0.78 g.100 g⁻¹(总脂肪酸)增加到1.78 g.100 g⁻¹(总脂肪酸);亚油酸(主要成分CLA)的含量从0.75 g.100 g⁻¹增加到1.27 g.100 g⁻¹;(2) 多不饱和脂肪酸n-6/n-3比值从4.6下降到2,以及总饱和脂肪酸从66 g.100 g⁻¹下降到60.4 g.100 g⁻¹。补充过饲料的山羊奶加工成干酪的产量为16.3 %,高于对照组的15.4 %。两种干酪的蛋白酶解和脂肪酶解的变化相似,并且没有检测出干酪风味缺陷。两种类型干酪的感官风味分数相似。因此,通过补充含有多不饱和脂肪酸的饲料,能够获得有益于人体健康的山羊奶和更合理脂肪酸组成的干酪,同时干酪还具有良好的感官特性。