Abstract

For the present study, two species of lactating animals, that is, Bubalusbubalis (Buffalo) and Bosindicus (Cow) was selected. In both types of milk, highest curd yield at 34°C was obtained at 60 min of cutting time after the addition of rennet followed by 39°C at 60 min of cutting time while at 28°C and  60 min of cutting time the yield was low and cutting times. This may be due to the improper rearrangements of casein network and the minimum curd fat retention level. The % total solids of curd were maximum at 28°C and at 60 min of cutting time may be due to the lower fat losses in whey and %TS were lower at 34°C when the cutting time was 90 min after the rennet addition because of the higher moisture content retention in the casein network due to the elongation in the protein network rearrangement time. The whey fat losses and curd fat retention values were minimized and maximized, respectively, between 28 and 39°C. The whey fat losses (WFL) and curd fat retention (CFR) were minimum at 28°C and maximum at 39°C. Increasing cutting time at 28°C results in firm gel with a good capability of fat retention and will decrease fat losses in whey. However, at temperature more than 30°C, coarsening of the milk gel occurs more rapidly, permeability of the gel is greater and the microsyneresis can occur at longer aging times. All these factors decreased the ability of the curd to retain fat. These results showed that the retention of fat is dependent on relative rigidity and structure of network at cutting. Below 28°C, there will be less gel firmness before cutting, therefore, increase in temperature will increase the rate of curd firming at best gel will be formed at 35°C. Above 35°C, the network becomes more rigid, rapid coarsening occur and the gel is more porous and all these assists the release of fat in whey and also the fat has high mobility at higher temperature which results in increase fat losses.

Key word: Gelation temperature, optimum cutting time, curd yield and quality.