PHYSICAL, CHEMICAL AND MICROBIOLOGICAL CHARACTERIZATION OF SUSTAINABLE SOAP PRODUCED WITH RESIDUAL VEGETABLE OIL

Abstract

Few collection and correct disposal actions are adopted for the recycling and environmentally appropriate destination of Residual Vegetable Oil (RVO). Sustainable soap produced from used cooking oil is an alternative for minimizing this type of waste. However, assessing its quality and proposing a correct standardization for the final product produced is a process that is rarely used, with artisanal techniques being adopted, with indefinite quantities, which can harm the health of recyclers and end consumers. For preliminary analysis, oil from the restaurant at IFRN campus São Paulo do Potengi will be collected, followed by use for artisanal production of sustainable soap. In the search for standardization of the soap produced, the chemistry laboratory at IFRN campus São Paulo do Potengi will be used, where the waste will be previously characterized, for definitions, proposals, comparisons and the Center for Water, Food and Effluent Analysis | NAAE for alignment of the probable contaminants identified. The physical-chemical parameters to be analyzed from the oil collected at (15 and 30 days) were: pH, determination of acidity, relative density, determination of moisture and volatile matter, determination of ether-insoluble impurities and microbiological control. To analyze the quality of the sustainable soap, the following parameters were analyzed at (7, 14, 21 and 28 days): pH, organoleptic aspects and average weight, loss of mass (during storage), formation of cracks, light resistance test and water resistance test, foam formation (Ross-Miles test). The results of the residual vegetable oil collected initially for the two storage periods showed a pH of 5.0 considered acidic and after the saponification reaction and the addition of sodium hydroxide it went to a basic pH of 12.0. The oil collected after 15 days had an acidity content of 1.02 mg KOH/g and 0.51% oleic acid, and after 30 days, an acidity content of 0.68 mg KOH/g and oleic acid of 0.34%, density was 0.9224 and 0.9262, respectively, moisture content of 0.28% and 0.23%, impurity content of 2.26% (15 days) and 0.69% (30 days). The collected oil did not show microbiological contamination. It was observed that the soap initially had a very basic pH and after 21 days of rest a pH of 10.0. Mass loss during storage was 1.47% and 1.50%, and mass loss after the water resistance test ranged from 3.42% to 23.43%. In the light resistance test, plaque formation was observed (15 days - 1 sample and 30 days - 3 samples), Ross-Miles test (30 cm of foam formation for both soaps). The soap produced with 15-day-old oil showed cracks in its structure.