Optimization of heat treatment and curcumin level for the preparation of anti-oxidant rich ghee from fermented buffalo cream by Central Composite Rotatable Design.

Adverse health effects of synthetic anti-oxidants have necessitated the use of natural anti-oxidants in food products. However, their incorporation may result into undesirable changes in physico-chemical and sensory attributes of the product. Hence, the present investigation was undertaken to prepare anti-oxidant rich ghee using curcumin (yellow pigment found in turmeric) as the natural anti-oxidant. Effects of varying curcumin levels (160-350 ppm), heating temperature (110-120 °C) and duration (16-22 min) on anti-oxidant, chemical and sensory attributes of ghee were studied. Increasing level of curcumin significantly increased the DPPH free radical scavenging activity and decreased the amount of conjugated dienes formation. Increasing heating time and temperature significantly decreased the anti-oxidant activity in ghee, but their combination significantly increased the activity. Increase in curcumin level and heating temperature improved the sensory attributes of ghee, but longer duration of heating decreased the same. Optimization using Central Composite Rotatable Design yielded 350 ppm of curcumin and heat treatment of 115 °C for 17.89 min for most acceptable, anti-oxidant rich ghee with a desirability value of 0.966. The model developed was found to predict the product characteristics adequately.