RESUMO
The kinetics of lipid oxidation includes a lag phase followed by an exponential increase in oxidation products, which cause rancidity. Current models focus on the slope of this exponential curve for shelf-life estimation, which still requires the measurement of full oxidation kinetics. In this paper, we analyzed the formation of lipid oxidation products in stripped soybean oil containing different levels of α-tocopherol. The lag phases of lipid hydroperoxides and headspace hexanal formation were found to have a strong positive correlation with the α-tocopherol depletion time. We propose that the kinetics of antioxidant (α-tocopherol) depletion occur during the lag phase and could serve as an early shelf-life indicator. Our results showed that α-tocopherol degradation can be described by Weibull kinetics over a wide range of initial concentrations. Furthermore, we conducted in silico investigations using Monte Carlo simulations to critically evaluate the feasibility and sensitivity of the shelf-life prediction using early antioxidant degradation kinetics. Our results revealed that the shelf life of soybean oil may be accurately predicted as early as 20% of the overall shelf life. This innovative approach provides a more efficient and faster assessment of shelf life, ultimately reducing waste and enhancing product quality.
Assuntos
Antioxidantes , alfa-Tocoferol , Óleo de Soja , Oxirredução , Óleos , CinéticaRESUMO
Antecedentes: La etapa de clarificación de hidrolizados de almidón para la producción de jarabes de glucosa es la principal causa de su producción por lotes, además de acarrear altos costos al utilizar filtros rotatorios al vacío, carbón activado y tierras diatomeas que aseguren la calidad del producto. Objetivos: Evaluar la etapa de clarificación de hidrolizados de almidón de yuca obtenidos por vía enzimática utilizando tecnología con membranas, a diferentes temperaturas, diámetros de poro de membrana y presiones transmembrana. Métodos: La clarificación se realizó utilizando un piloto compuesto por un tanque enchaquetado, donde se llevó a cabo la reacción de hidrólisis. La filtración se realizaba conectando el tanque a una bomba que permitía enviar el fluido al módulo membranario; la presión transmembrana fue fijada con una válvula a la salida del módulo. Los experimentos se llevaron a cabo usando membranas con diferentes tamaños de poro en un diseño factorial 22, evaluando dos niveles de temperatura (50 y 70ºC) y dos niveles de presión transmembrana (0,15 y 0,30 MPa). Se midieron los caudales obtenidos para el retenido y el permeado. Las muestras obtenidas fueron analizadas para evaluar la calidad del permeado (turbidez, cantidad de proteína retenida, contenido de materia seca y ºBrix). El análisis estadístico se llevó a cabo con el software Statgraphic Centurion XVI.I®. Resultados: Los resultados obtenidos mostraron que las presiones transmembrana (0,15 y 0,30 MPa) y temperaturas (50 y 70ºC) evaluadas no influyen significativamente sobre la permeabilidad ni calidad del permeado (p-valores > 0,05) permitiendo trabajar con la menor presión tranmembrana (menor desgaste de equipos y menor gasto energético), y a la temperatura de hidrólisis, lo cual permitiría trabajar bajo condiciones de producción en continuo. Además, se observó que es posible utilizar membranas con diámetro de poro de hasta 0,8 µm; aumentado hasta en 5 veces la productividad y disminuyendo la turbidez en un 99%. Conclusiones: Es posible utilizar membranas cerámicas de microfiltración de hasta 0,8 µm, en condiciones moderadas de presión transmembrana y a la temperatura de hidrólisis para la clarificación de hidrolizados de almidón de yuca sin disminuir la calidad del permeado.
Background: Clarification step of starch hydrolysates for the production of glucose syrups is the main responsible for batch production; in addition, it causes high costs when using rotary vacuum filters, activated carbon and diatomaceous earth to ensure product quality. Objective: To evaluate the clarification step of hydrolyzed cassava starch obtained enzymatically, using membrane technology at different temperatures, membrane cut-off and transmembrane pressures. Methods: Clarification was conducted using a pilot composed by a jacketed tank, where the hydrolysis reaction was carried out. The filtration was performed by connecting the tank to a pump to send the fluid to the membrane carter; transmembrane pressure was fixed with a valve placed at the end of the module. The experiments were carried out using membranes with different cut-off sizes in a factorial design 22, two temperatures (50 and 70°C) and two transmembrane pressure levels (0.15 and 0.30 MPa) were evaluated. The flows obtained for the retentate and permeate were measured. The obtained samples were analyzed to assess the permeate quality (turbidity, amount of retained protein, dry matter content and °Brix). Statistical analysis was performed with software Statgraphic Centurion XVI.I®. Results: The results showed that the pressures (0.15 to 0.30 MPa) and temperatures (50 and 70°C) evaluated did not influence significantly the permeability, or the quality of the permeate (p-values > 0.05), it can allow to work with lower pressure (less wear on equipment and less energy), at hydrolysis temperature, it would allow to work under conditions of continuous production. Moreover, the possibility to use membranes with pore diameters up to 0.8 µm was observed; it allow to increase up to 5 times the productivity and decrease the turbidity by 99%. Conclusions: It is possible to use ceramic microfiltration membranes up to 0.8 µm in moderate transmembrane pressure, at hydrolysis temperature for clarification of cassava starch hydrolysates without decreasing the quality of the permeate flow.
