Dados do Trabalho

Título

MATHEMATICAL MODELING AND EVALUATION OF THE STABILITY OF STORED SOYBEAN OIL AFTER OPENING THE PACKAGE IN DIFFERENT CONDITIONS

Introdução

The consumption of vegetable oils has increased worldwide, due to the lower price and high availability on the domestic market, soybean oil is the most consumed in Brazil. The oxidative stability of vegetable oils is dependent on physical factors and the influence of chemical mechanisms during storage. There are well-documented methods to define this stability, however the use of mathematical modeling to simulate quality parameters is useful to carry out projections and better understand the behavior of the product. Therefore, this work aimed to evaluate the stability of soybean oil after opening the packaging during storage under 5 home-simulated conditions and propose mathematical models capable of simulating the evaluated quality parameters.

Material e Métodos

Storage conditions were: (a) packaging at room temperature, exposed to light and oxygen (lid open); (b) room temperature, exposed to light, lid closed; (c) room temperature, in the dark, lid open; (d) room temperature, in the dark and lid closed; (e) refrigerated temperature (1-3°C), in the dark, lid closed. Free fatty acid content (Ca 5a-40) and peroxide index (Cd 8-53) from AOCS methods was carry out weekly for 19 weeks (until the expiration date indicated by the manufacturer). The data were analyzed using statistical tests and the partial least squares method was used for modelling.

Resultados e Discussão

All samples did not exceed the amount of free fatty acids permitted by Brazilian legislation (< 0.3%). However, the peroxide index was exceeded in condition (a), reaching 11.24 mEq.Kg-1 in 11 weeks, and (c), presenting 10.53 mEq.Kg-1 in 16 weeks, even within the expiration date. The models proposed for simulating the peroxide index were promising, demonstrating a small variation between the value predicted by the model and that observed experimentally. The most impactful factors for oxidative stability for soybean oil were the presence of oxygen (a; c) and light exposure (a; b). Samples that were not exposed to these factors (d; e) did not exceed the maximum values allowed. The oil stored in the refrigerator (e) did not present significant changes (p>0,05) over time. Thus, storage conditions at home directly influence the quality of oil after the packaging has been opened by the consumer.

Conclusão

The models proposed for simulating the peroxide index were promising, demonstrating a small variation between the value predicted by the model and that observed experimentally. Among the storage conditions studied, the most impactful factor for oxidative stability was the presence of oxygen and light exposure. Samples that were not exposed to these factors did not exceed the maximum values stated by legislation during storage within the expiration date. Therefore, keeping the soybean oil packaging closed, protected from light and in a cool place directly influences the quality of the oil stored after opening at home by the consumer.