Effect of dried liquorice root supplementation on chemical-nutritional quality of dairy products obtained from goats

Enriching the goat’s diet with plant extracts, rich in bioactive compounds, allow to improve the chemical-nutritional properties of dairy products. Liquorice has anti-inflammatory, antimicrobial, antioxidative effects associated with the presence of compounds, as triterpene saponins, flavonoids and coumarins The aim of the present work was to evaluate the effect of dietary integration with 8% of dried liquorice root on chemical-nutri- tional quality of goat milk and cheeses. The study was conducted for 60 days on Saanen goats divided into two groups: a control group (CG) and an experimental group (LG+) whose diet was supplemented with liquorice. Milk samples were collected to determinate chemical-nutritional composition and fatty acids profile (FA) at 30 and 60 days from the beginning of the study. At the end of the experiment, cheeses produced with CG and LG + bulk milk were analysed for chemical–physical parameters at 3 (T3) and 60 (T60) days of ripening. A different FA profile and a significant increase in proteins (p<.01) and casein (p<.01) percentage but no variation in lipids, lactose, urea and in FA were observed in LG+milk samples respect to CG milk. Regarding cheeses, no variation in lipid and protein but a lower water content (p<.05) were found in LG + T3 and T60 cheeses, this reflected in a different texture. Indeed, the LG+cheeses were harder, more elastic and more gummy than the CG cheeses and these differences were observed both in fresh and aged cheeses. Moreover, the LG + cheeses showed a yellowish colour probably correlated to the presence in LG + milk of specific compounds of liquorice roots, such as tannins, carotenoids and ascorbic acid which have antioxidant activity and are also respon- sible for the yellow colour. A greater presence of antioxidant compounds deriving from liquorice roots can be also correlated with greater oxidative stability found in both LG + T3 (p<.05) and T30 (p<.05) cheeses. Different families of volatile compounds were detected in T30 cheeses obtained from the two groups. A significant reduction of octanoic acid (p<.05) and a significant increase in nonanal (p<.01) were found in LG+T3 cheeses, instead in LG + T60 cheeses, significant increases of 3-methyl, 1-butanol (p<.01) and acetoin (p<.05) have been found. In conclusion, it is possible to assert that the integration with liquorice has modified chemical and technological properties of goat cheeses, improving the oxidative stability and inducing changes in texture and colour.