Beef tallow/high oleic sunflower oil shortenings produced by chemical interesterification optimized by response surface methodology (RSM): Effect of processing conditions on physical properties

Response surface methodology (RSM) was used to obtain two shortenings (IEA and IEB) by chemical interesterification (CI) of beef tallow (BT) and high oleic sunflower oil (HOSFO) with melting points of 35.5°C and 38.5°C, higher OOO and SOO contents, and lower PPP, SOS, POS, and POP percentages than BT. The maximum percentage of HOSFO in the formulations and the optimum time, temperature, and catalyst concentrations to achieve the desired physicochemical properties for the shortenings were determined from the model. The shortenings were characterized, and the effects of processing and storage conditions were explored. HPLC/MS analysis showed that the mono and di-unsaturated triacylglycerols (TAGs) had unsaturated fatty acids at the sn-2 position. The changes in chemical composition due to the interesterification process were mostly differences in percentages more than in the type of TAGs present. IEA and IEB showed profiles of solid fat content versus temperature and G' values similar to those reported for soft and firm margarine, respectively. Under static cooling conditions, for BT, BA, BB, and IEB, the α-form was the main polymorph, whereas the β′-tendency increased with increasing temperature and slow cooling rate. IEA crystallized in the β′-form between 20 and 32°C. Under dynamic cooling conditions, nucleation was impeded at fast cooling rate and promoted at slow rate as evidenced by induction times of crystallization. Interesterification decreased the MP, increased the β′ tendency that lasted at least 8 months at 25°C, and improved the nutritional value of shortening making them suitable as trans-fat alternatives.