Cinética de secagem do camarão-da-amazônia (macrobrachium amazonicum) por refractance window

Abstract

In the Amazon region, freshwater prawns are distributed throughout the hydrographic subbasins. Macrobrachium amazonicum, popularly known as the Amazon Prawn, is the species with the highest production in the region and has the greatest potential for fishing and aquaculture. Its capture and commercialization are one of the main and sometimes the only source of income for several families, especially those living along the riversides, due to the final destination of this production, with distribution in ports in Pará and Amapá. Although prawns are known for their high nutritional value, this characteristic can be affected when this food does not undergo a suitable preservation method to extend its shelf life. Given the importance of this food, it is necessary to explore new technologies, such as the use of ethanol in food pretreatment - which has the ability to dissolve cell membranes, alter the sample structure to be dehydrated, improve moisture transfer, and reduce drying time when combined with Refractance Window (RW) drying, a method that is known in literature as a technological innovation, in view of its advantages, which are: it retains bioactive compounds; it preserves quality and increases the product's shelf life; it has energy efficiency; it involves lower operating costs; and it is environmentally viable. The objective of this dissertation was to evaluate the performance of the RW drying method associated with ethanol pretreatment assisted by mechanical agitation and ultrasound in the dehydration process of an animal-based matrix (Amazon Prawn – Macrobrachium amazonicum). Simultaneously, mass transfer parameters and thermodynamic properties controlling the drying process were determined. The samples (peeled abdomen) were pretreated with 100% ethanol (1:18) under mechanical agitation (PTAG) and ultrasound (PTUS) for 10 minutes, in addition to the sample without pre-treatment (SPT). Then, the samples subjected to the drying process in RW at temperatures of 50, 70, and 90ºC. The parameters of the mathematical models by Dincer & Dost, Crank, and Motta Lima and Massarani were estimated using Origin Software 2023. The analyses were done in duplicate using analysis of variance (ANOVA) and the Tukey test at 5% probability. Additionally, the quality of fit for the experimental drying kinetics (CS) data was estimated by the coefficient of variation (R²) and the chi-squared (X²). After obtaining the data, the moisture determination indicated that at a temperature of 90ºC, the PTAG (12.93 ± 0.16%) and PTUS (11.86 ± 1.59%) samples had the lowest final moisture content. Through ANOVA, the results show that the ASPT and PTUS samples presented a significant difference, while the PTAG sample did not present a significant difference (p<0.05) between the temperatures. Regarding the mathematical modeling of CS, the Motta Lima and Massarani model showed the best fit to the experimental data, with R² ≥ 0.98 and reduced X² values for all temperatures. Thermodynamic properties were calculated based on data obtained by the Dincer & Dost model, such as activation energy (Ea) with a range between 42.97 - 30.37 kJ/mol; positive enthalpy (ΔH) values, indicating the need for heat energy for the drying process to occur; and negative entropy (ΔS) values, indicating that the process occurred without a significant increase in disorder in the system. Based on the results, it was evident that the combination of pretreatment with ethanol assisted by AG and US, coupled with RW drying, significantly reduced the time required for drying the Amazon Prawn.