Physical and chemical properties of commercial medium‐ and long‐carbon‐chain triglyceride products: triglyceride composition, volatile substances, thermodynamic properties

Abstract BACKGROUND Medium‐ and long‐chain triglycerides (MLCTs) are structured lipids composed of medium‐chain fatty acids (MCFAs) and long‐chain fatty acids (LCFAs), which have been increasingly applied in the food, medical, and nutritional industries because of their unique metabolic and physiological properties. However, most existing studies have focused on the synthesis and nutritional evaluation of MLCTs under laboratory conditions. In contrast, limited research has systematically compared the compositional characteristics, oxidative stability, volatile profiles, and thermal behavior of commercially produced MLCT products. Therefore, this study aimed to comprehensively analyze the physicochemical and structural properties of five representative commercial MLCT products to provide data supporting their functional and technological utilization. RESULTS The structured fat emulsion of LW (Li Wen) contained high proportions of MLCTs and MCFAs (68.17% and 31.39%, respectively) and exhibited the highest oxidative stability index of 7.2 h. A total of 82 glyceride species were identified across five commercial MLCT products. Principal component analysis indicated that LLCy (linoleic acid–linoleic acid–caprylic acid) contributed significantly to the compositions of LW, KRD (Kang Rui Da), and QY (Qing Yi); OOCa (oleic acid–oleic acid–capric acid) was predominant in RQ (Ri Qing); and CyCyLn (caprylic acid–caprylic acid–linolenic acid) was characteristic of FH (Fu Hui). Differential scanning calorimetry revealed major exothermal peaks between −27.35 and −50.64 °C during cooling, while two endothermal peaks, except in LW, appeared between −21.25 and −29.88 °C during melting. Attenuated total reflectance–Fourier transform infrared spectroscopy confirmed the MLCT foodprints of 1056 cm −1 , and the absence of peroxides and of trans fatty acids (TFAs) in all MLCTs products. Microstructural observations showed that LW, QY, and FH exhibited uniform, fine, and densely packed crystal morphologies. CONCLUSION To the best of our knowledge, this study provides the first comprehensive characterization of commercially available MLCT products, offering fundamental insights that may facilitate their broader application in functional foods and nutraceuticals. © 2026 Society of Chemical Industry.