The effect of housing system of Simmental cows on processing suitability of milk and quality of dairy products

The aim of the study was to determine the effect of two feeding systems (TMR - group I, pasture - group II) on physicochemical properties of milk, its suitability for making rennet cheese and butter, and sensory properties of these products. The study was conducted with second and third lactation Simmental cows between 30 and 200 days of lactation. Total milk yield for the lactation period was 6000 litres. Somatic cell count during the study was considerably higher in group I (350 thous.ml(-1) on average) than in group II (250 thous.ml(-1) on average). During the study milk samples for chemical analyses were collected once a month. Milk of group II cows was characterised by lower active and potential acidity, higher ethanol stability, and greater tolerance to heat treatment. Rennet-induced clotting time was significantly (p<0.05) shorter for milk of group II cows (202 sec) compared to that of group I cows (248 sec). Sensory evaluation showed that group II milk was characterised by better taste, more intense (p<0.05) aroma, better consistency and significantly (p<0.05) more intense yellow colour, which received a higher score. Rennet cheese yield per 101 of milk was similar in both groups; however, cheese made from the pasture group milk had a more compact clot. The organoleptic evaluation showed that cheese from group II had a significantly (p<0.05) more intense colour (4.73 vs. 4.07 pts), better consistency (4.87 vs. 4.00 pts) as well as better taste (4.87 vs. 4.20) and aroma (4.73 vs. 4.47) when compared to group I. Immediately after production, butter made from milk of pasture-fed cows had considerably better fat parameters. Butter fat from group II was characterised by a higher iodine number, which measures fat unsaturation level. The higher unsaturated fatty acid content contributed to a decrease in solidification and melting points of fat and to more intense lipolytic and oxidative processes, as evidenced by the higher acid number, peroxide value and TBA value. At the beginning of storage, butter produced from milk of group II cows received significantly (p<0.05) higher scores for colour and consistency as well as higher (p<0.05) scores for aroma and taste. At 30 days of storage no differences were observed between the groups. The results of the present experiment show that pasture feeding has a positive effect on the processing suitability, of milk and the sensory properties of rennet cheese and butter, but the produced butter is more susceptible to undesirable changes during storage.