Abstract #435

# 435
Influence of herd diet (pasture-based vs. TMR) on the composition, ripening and metabolome of continental-type cheeses.
J. J. Sheehan*1, 1Teagasc Food Research Centre Moorepark, Fermoy, Co. Cork, Ireland.

In response to growing consumer interest in pasture fed dairy products, research was conducted on the characteristics of Continental type-cheese derived from milks produced from cows fed indoors on total mixed ration (TMR), or pasture fed cows on grass only (GRA) or grass mixed with clover (CLO). A preliminary study showed that the curd moisture loss rate constant (k/min) was similar for curds from protein-standardised TMR, CLO and GRA milks, showing minimal feed-induced variations in syneresis. Maasdam cheeses manufactured from standardized milks derived from the feeding systems showed that pasture-derived cheeses had significantly lower L* (whiteness) and higher b* values (yellowness) compared to TMR-derived cheeses. Acetate levels were significantly lower in CLO and butyrate levels significantly higher in TMR compared to the other cheeses. Grass-fed cheese had significantly higher scores for smooth texture, ivory color and shiny appearance compared to TMR. The influence of feed type was minimal on cheese yield, composition and on indices of glycolysis, lipolysis and proteolysis during ripening. The untargeted metabolic profiles of the ripened Maasdam cheese samples were profiled using high-resolution nuclear magnetic resonance (1H NMR), high-resolution magic angle spinning NMR (1H HRMAS NMR) and headspace (HS) gas chromatography mass spectrometry (GC-MS). On comparing the 1H NMR metabolic profiles, TMR-derived cheese had higher levels of citrate compared to GRA-derived cheese. The major differences between outdoor or indoor feeding system on cheese metabolites were detected in the lipid phase, as indicated by 1H HRMAS NMR. The toluene content of cheese was significantly higher in GRA or CLO compared with TMR cheeses and dimethyl sulfide was identified only in CLO-derived cheese samples as detected using HS GC-MS. Overall, this study shows that once milk is standardized, cheese manufacture, composition and yield properties are not influenced by herd diet while certain sensory characteristics and a small number of compounds and lipid derived metabolites differ.