Utilization of by-products Derived from the Virgin Coconut Oil Manufacturing Process for Soap Preparation

Abstract

The virgin coconut oil manufacturing process produces two major wastes, coconut whey protein and wastewater, which are generally discarded, causing environmental problems. To add value to such wastes, the present study aimed to develop a soap product using coconut whey protein and wastewater instead of virgin coconut oil (VCO) and water, respectively. The objective of the study was to investigate the influence of the VCO to the coconut whey protein ratio on the quality of the soap. The ratio of virgin coconut oil to coconut whey protein (w/w) was varied at 5 levels: 100:0 (treatment 1 control, S1(100:0)), 75:25 (treatment 2, S2(75:25)), 50:50 (treatment 3, S3(50:50)), 25:75 (treatment 4, S4(25:75)) and 0:100 (treatment 5, S5(0:100)). Results revealed that an increase in the proportion of coconut whey protein affected the physical properties of the soap, i.e., a decrease in the soap’s hardness, an increase in rancidity, volume of flash foam and foam stability. However, increasing the proportion of coconut whey protein did not significantly affect the solubility, as expressed in terms of the erosion (p≥0.05). It was found that as the percentage of coconut whey protein increased, namely ≥50%, the quality of the soap produced declined: the ethanol-insoluble matters of S4(25:75) and S5(0:100) were 1.53 and 1.95%, respectively, while the total fatty matters of S4(25:75) and S5(0:100) were 59.8 and 52.1%, respectively, which do not conform with the soap standards specified by the Thai Industrial Standards Institute (2000) and Kasetsart University-Bank for Agriculture and Agricultural Cooperatives (2007). The pHs of all treatments were in the range of 9.4–9.8, which is considered suitable for use. Both the physical and chemical properties of soap prepared using the ratio of virgin coconut oil to coconut whey protein of 75:25 (S2(75:25)) were comparable to those of virgin coconut oil soap (control) and conformed well with the soap standards.