Abstract #434

# 434
Factors influencing the flavor of bovine milk and cheese from grass-based versus TMR-based milk production systems.
K. Kilcawley*1, 1Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland.

The impact of diet on the sensory properties of bovine milk and dairy products is complex due to the wide range of on farm and production factors that are potentially involved. It is well established that pasture affects the color of milk and dairy products due to β-carotene content, and that nutritional and potentially textural properties are altered due to dietary factors influencing fat synthesis. Very little research has been undertaken on aromatic volatile compounds derived from diet that may affect sensory perception. It is obvious that any potential effect depends upon their concentration and odor activity. We have found evidence of direct transfer (digestion/absorption or inhalation), and indirect transfer (rumen metabolism) of volatiles and via secondary mechanisms (lipid oxidation, Maillard reactions, de novo systhesis) for volatile incorporation into bovine milk. We found 3 volatile compounds present at higher levels in milk derived from pasture; toluene, dimethyl sulfone and p-cresol, that may be potential biomarkers for pasture feeding based on concentration. In our studies only p-cresol affected flavor, which has a ‘barnyard’ or ‘cowy’ attribute and is derived from the rumen metabolism of β-carotene and aromatic acids which are higher in pasture diets, but also from the rumen metabolism of isoflavones present in clover. We are also aware that US consumers have a lower threshold for this ‘barnyard’ ‘cowy’ attribute than Irish and Chinese consumers.