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Soybean oil is the most consumed oil worldwide due to its cheapness but presented a weak thermo-resistance due to its richness in poly-unsaturated fatty acids. This study aims to improve the thermo-stability of refined soybean oil by blending it with some cold-pressed oils. For this, cold-pressed and soybean oils were firstly characterized (K232, K270, acidity, peroxide value, iodine value, induction time, phenolic contents, and antioxidant activity). Then, binary blends of each cold-pressed oil (30%) with soybean oil (70%) were analyzed before and after heat treatment (170 °C for 10 h/day for 5 days) followed by the application of the simplex lattice mixture design in order to optimize the combination of the three best cold-pressed oils. The changes in fatty acid profiles were assessed by gas chromatography (GC-FID). The results revealed that soybean oil presented the best physicochemical traits, while cold-pressed oils expressed high levels of phenolic contents and antioxidant activities. From the six binary oil blends, soybean oil mixed with lentisk, sesame, or almond oils were selected for their best thermo-stability. The simplex lattice mixture design, applied for these three chosen oils, indicated that the combination of soybean oil (70%) with lentisk and sesame oils (17.7 and 12.3%, respectively) was considered the optimal blend that gives the maximal thermo-stability improvement to soybean oil. GC-FID analysis showed that fatty acids, particularly linoleic and linolenic acids, were more conserved after heat-treatment in optimal oils blend than soybean oil. This study clearly demonstrated that lentisk and sesame oils enhanced the thermo-resistance of soybean oil, and the findings of this study could be used as an integrated model in oil and fat industries.

This study was carried out to optimize Microwave-assisted extraction (MAE) process and assess the possibility of using Opuntia ficus-indica (OFI) seeds as natural antioxidant additives in food. Box-Behnken design was used to optimize total phenolic contents (TPC) and antioxidant activity DPPH• (AA) extraction conditions. The models were verified and validated and the interactions between the factors were studied. Under the optimal conditions, corresponding experimental values for TPC and AA were 5.22± 0.12 mg GAE/g DW and 2.30±0.27 mg GAE/g DW, respectively. Seven and eight compounds were identified in TPC and AA under optimal conditions, respectively, using High-Performance Liquid Chromatography (HPLC) coupled to Mass Spectrometry (MS) analysis. Ferulic acid glucoside was the most concentrated compounds in the OFI seed extract. Rancimat test showed that OFI seed extract gives the highest oxidative stability with 150 ppm. The presented data could be a reliable guideline for establishing full-scale, cost-effective and resource-effective food industry process. [ABSTRACT FROM AUTHOR]