Physical Chemical Properties of Fermented and Roasted Rambutan Seed Fat (RSF) as A Potential Source of Cocoa Butter Replacer

Abstract

Rambutan (Nephelium opossum L) is one of the most important tropical fruits that is originally found in Malaysia, Thailand, the Philippines, Vietnam, Borneo and other countries in this region. The industrial processing of this fruit produces seeds and peels as waste materials. The aim of this work was to determine the physical-chemical properties of fermented-roasted Rambutan seed fat (RSF) and its mixtures with Cocoa butter (CB) in term of viscosity, texture (hardness), thermal stability, and fatty acid composition, and free fatty acid, acid value. The mixtures M3, M4, and RSF which possess similar crystal formation showed almost similar hardness index in the range of 11.18 to 24.77. The mixtures M1 and CB exhibited higher hardness index than M2, M3, M4 and RSF in the range of 57.55 to 63.85. The results showed that a low viscosity was observed in the mixture CB and M1 with increasing the temperatures at 35, 40 and 50 o C whereas, a high viscosity was observed in the other mixture such as M3, M4, and RSF with increasing the temperature, respectively. The result found that the major fatty acid composition was present in CB (100%CB+0%RSF) and M1 (80%CB+20%RSF), such as palmitic, stearic and oleic acid, respectively. The results showed no significant differences (P > 0.05) in FFA among CB (2.72±0.65%), M1 (3.01±0.32%) and M2 (3.47±0.16%). At the same time, the results of A.V showed significant differences (P < 0.05) among CB (4.68±1.29), M1 (5.98±0.64) and M2 (6.92±0.33) mgKOH/g, respectively, but M1 value was very close to CB value. The results exhibited that CB and M1 had a lower viscosity than M2, M3, M4 and RSF with increasing temperature. From these results, it was found that it is possible to utilize rambutan seed fat as a cocoa butter replacer in a suitable ratio depending on the final products.