The stability of soybean germ phytosterols (SGPs) in different lipid matrixes, including soybean germ oil, olive oil, and lard, was studied at 120, 150, and 180 °C. Results on the loss rate demonstrated that SGPs were most stable in olive oil, followed by soybean germ oil, and lard in a decreasing order. It is most likely that unsaturated fatty acids could oxidize first, compete with consumption of oxygen, and then spare phytosterols from oxidation. The oxidation products of SGPS in non-oil and oil systems were also quantified. The results demonstrated that at relatively lower temperatures (120 and 150 °C), SGPs’ oxidation products were produced the most in the non-oil system, followed by lard, soybean germ oil, and olive oil. This was consistent with the loss rate pattern of SGPs. At a relatively higher temperature of 180 °C, the formation of SGPs’ oxidation products in soybean germ oil was quantitatively the same as that in lard, implying that the temperature became a dominative factor rather than the content of unsaturated fatty acids of lipid matrixes in the oxidation of SGPs.

BACKGROUND Caffeic acid (CA) has anti‐oxidation and anti‐inflammatory. However, the poor hydrophilicity of CA limits its biological activities. In this work, hydrophilic glyceryl monocaffeate (GMC) was synthesized by esterification using different caffeoyl donors (deep eutectic solvent and solid CA). Cation‐exchange resins were used as the catalysts. The effects of reaction conditions were also investigated. RESULTS The mass transfer limitation of esterification was eliminated using deep eutectic solvent. Compared with the previous catalysts (immobilized lipase Novozym 435), an economic cation‐exchange resin, Amberlyst‐35 (A‐35), showed good catalytic performance for GMC preparation. The activation energies of GMC synthesis and CA conversion were 43.71 kJ mol−1 and 43.07 kJ mol−1, respectively. The optimal reaction conditions were a temperature reaction of 90 °C, catalyst load of 7%, glycerol/CA molar ratio of 5:1 (mol mol−1), and reaction time of 24 h, which resulted in a maximum GMC yield and CA conversion of 69.75 ± 1.03% and 82.23 ± 2.02%, respectively. CONCLUSION The results of the work showed a promising alternative for the synthesis of GMC. © 2023 Society of Chemical Industry.