Bioactive Compounds in Goat Milk and Cheese: The Role of Feeding System and Breed

Abstract

This chapter provides an introductory overview of some bioactive compounds in goat milk, presenting a selection of key results from literature. The aim of the chapter is to review the effects of the feeding system and of the breed on goat milk and cheese fine quality in order to identify management options aimed at improving the nutraceutical characteristics of milk and dairy products. We will discuss a series of case studies focused on the assessment of the effects of feeding system and breed and their interaction on specific health-promoting bioactive compounds: (i) fatty acid (FA) profile, (ii) antioxidant compounds and (iii) oligosaccharides (OS). Experimental data will be discussed high-lighting the potential role of local Mediterranean breeds for the production of functional dairy products. centrifuged × g, min). After the the was a Buchner rinsed with CHCl 3 (30 ml) and then again filtered. The chloroform-lipid was dried over anhydrous Na 2 SO 4 , rinsed with CHCl 3 (30 ml) and concentrated using a rotary evaporator at 30°C. The residue was stored at −80°C for lipid determination. Lipid extract was methylated adding hexane (1 ml) and 2 N methanolic KOH (0.05 ml). Gas chromatograph analysis was performed on a Varian model 3800 GC instrument fitted with an automatic sampler (CP 8410) for a multiple injection. Fatty acid methyl esters (FAME) were separated through a cyanopropyl polysiloxane (DB 23, J & W) fused silica capillary column (60 m × 0.25 mm i.d.). Operating conditions were a helium flow rate of 1.2 ml/min, a FID detec-tor at 250°C and a split-splitless injector at 230°C with a split ratio 1:100. The column tempera-ture was held at 60°C for 5 min after sample injection (1 μl), increased at 14°C/min to 165°C and at 2°C/min to 225°C and held at 225°C for 20 min. The individual fatty acid peaks were identified with reference to the retention times of standard of CLA isomers trans-11 97% and trans-10, cis-12 3%; Larodan, and a known mixture of standards (FAME, Sigma). Fatty acids were expressed as percentage of total FAME. These results show that cholesterol was highly protected against oxidative reactions when herbage was the only feed or was dominant in the goat diet. A strong positive correlation between herbage intake and DPA values allows to identify a linear regression: y = 0.12 x + 5.52, where y = DPA (×10 −3 ) and x = contribution of grazed herbage intake to the animal diet calculated as a percentage of the maximum intake of mature Maltese goats (1100 g/d = 100% grazing). The DAP index equal to 7.0 × 10 −3 was able to distinguish dairy products when the grazed herbage in the goats’ diet exceeded 15%. The reliability of DAP to measure the antioxidant protection of cholesterol appeared more effective when the feeding system was based on grazing than when cut herbage or zero grazing was utilised indoors by animals.