Characterization of three varieties of Malaysian rambutan seed oil

Introduction: Rambutan seed is considered a waste by-product of fruit processing. The seed waste is usually discarded or disposed in a large amount without an economic value which has become an issue that needs to be solved. However, the seed contains a considerable amount of crude fat. Aim: the purpose of this study was to characterize the physicochemical properties of oil of the seeds of three varieties of Malaysian rambutan fruit (R4, R7 and Serjan) for potential application. Materials and methods: In this study, colour, refractive index, viscosity, free fatty acid content, peroxide value, p-anisidine value, iodine value, saponification value, unsaponifiable matter, fatty acid composition, thermal behaviour, melting point, and solid fat content of rambutan seed oil from three varieties were used to characterise physicochemical properties of rambutan seed oil. Results: No significant differences (p > 0.05) were observed for free fatty acid content, peroxide value, p-anisidine value, saponification value, unsaponifiable matter, colour, viscosity and refractive index among three varieties. There are significant differences (p < 0.05) in the iodine value and melting point among the rambutan seed oil of three varieties. Varieties R7 and R4 seed had the highest (37.62 ± 0.10 %) and lowest (34.25 ± 0.07 %) crude fat content, respectively. Oleic (37.75-40.58 %) and arachidic (35.24-36.89 %) acids were the major fatty acids in the oil. Both melting and crystallization curves showed that the oil exhibited three distinct peaks. The complete melting and crystallization onset temperatures of the oil were 24.76–26.57°C and 21.19–22.79°C, respectively.Conclusions: This study reveals that the rambutan seed oil has potential to be used in various sectors of food industry. Therefore, rambutan seed can be fully utilized and, subsequently, the amount of waste can be minimized.