Rambutan seed as a new promising unconventional source of specialty fat for cosmetics

• Maceration in n-hexane for 1 h was feasible for rambutan seed fat extraction.
• Re-using of the solvent gave insignificant differed extractive yields.
• Oleic and arachidic acids were the major fatty acids.
• Physicochemical properties of the fat for an industrial practice were reported.
• The stable bar and liquid soaps containing the rambutan seed fat were developed.

Rambutan is commercialized for fresh consumption and industrially processed leaving seed as a major residue. Rambutan seed from the industry is worthy of attention for certain industrial applications and feasibility. Extractive yields and fatty acid compositions of rambutan seed fat obtained under different extraction conditions were studied to assess possible applications on an industrial scale. Maceration in n-hexane for 1 h was shown to be feasible for rambutan seed fat extraction (30.12 ± 0.04%). Re-use of the solvent gave non-significantly different extractive yields (p > 0.05). Oleic and arachidic acids were exhibited as the major fatty acids (31.08 ± 0.75% and 28.65 ± 0.72%) followed by gondoic, palmitic, stearic, isooleic, behenic, linoleic and palmitoleic acids. The physicochemical properties of the fat feasible for an industrial practice were determined, including acid (4.35 ± 0.00 mg KOH/g), iodine (44.17 ± 0.30 g I2/100 g), peroxide (1.00 ± 0.00 g/g), saponification (246.73 ± 0.10 mg KOH/g) and unsaponified (0.10 ± 0.00%) values. This bio-fat with a moisture content of 1.77 ± 0.12% was melted at 46.05 ± 0.05 °C. Stable bar and liquid soaps containing rambutan seed fat were developed. Such application demonstrates the potential of rambutan seed fat as a raw material for the cosmetic and personal care industries. The extraction method was modified to meet requirements for industrial feasibility. This unconventional bio-fat with a specification in terms of fatty acid profiles and physicochemical properties is proposed. Furthermore, the fat is comparable with other vegetable oils and cosmetic ingredients, and is compatible with other cosmetic ingredients.

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