Interesterification of fat blends using a fermented solid with lipolytic activity

Enzymatic processes to produce interesterified fats and oils with desirable properties to incorporate in margarines and shortenings are currently quite expensive. In the current work, fermented solids, produced by growing Rhizopus oryzae and Rhizopus microsporus on a mixture of sugarcane bagasse and sunflower seed meal, were able to catalyze the interesterification of a mixture of palm stearin, palm kernel oil and a concentrate of triacylglycerols enriched with ω-3 polyunsaturated fatty acids (“EPAX 4510TG”). The best conditions for the interesterification reaction with the fermented solid produced by R. oryzae, found by response surface methodology, were a temperature of 65 °C, a palm stearin content of 38% and an EPAX content of 15%. Under these conditions, after 24 h, the product had a solid fat content at 35 °C (SFC35 °C) of 2.3%, making it suitable for the production of margarines and shortenings. If the reaction time can be decreased, this process has good potential to lower the costs of the enzymatic interesterification process, since the fermented solids are reasonably cheap to produce and their use avoids the recovery and immobilization steps that are required for lipases produced by submerged fermentation.