Ampliação de escala do processo de fermentação semissólida utilizando pedúnculo de caju seco para produção de pectinases.

Abstract

Objective of this work is to study the pectinases production, using cashew apple dry bagasse (Anarcadium occidentale L.) as substrate and Aspergillus niger CCT0916 as microorganism, aiming to increase the scale of fermentation process and enzyme extract application in production process of tropical fruit juices. Therefore, it was necessary to verify the synergistic influence of various factors on fermentation process laboratory scale. Thus, it was found to influence the amount of spore inoculated, initial moisture content of the medium, nitrogen source concentration and temperature, in response to maximal enzyme activity. The highest polygalacturonase activity (33.27 U/g) was found with 50 %(w.b.) initial moisture, 106 spores per gram of wet medium, 1.5 %(m/m) of ammonium sulfate and 35°C at 29 hours of fermentation. The models for 21, 29 and 54 hours of fermentation were considered statistically significant at 95% confidence. It was noted that humidity has a greater influence on process, having a positive influence on all fermentation times. It was also analyzed the influence of solid medium thickness and fermentation temperature, through solid state fermentation process using a tray bioreactor. The higher polygalacturonase activity observed (15.72 U/g) was obtained with 40 mm thick layer of medium and temperature of 23°C at 69 hours of fermentation. Models for 45 and 69 hours of incubation were statistically significant to 95% confidence level. Temperature is the variable that most influences the process. It was studied the stability of the enzyme polygalacturonase in relation to temperature and pH in order to further application of enzymatic complex in viscosity reduction and increase the clarity of tropical fruit juices. Optimum temperature stability of polygalacturonase enzyme was 40°C. Optimum pH is between 2.5 and 3.5. With up to 30 minutes of exposure to the optimum temperature and pH, enzyme remained at 90% of its activity. After fermentation by the solid state process, it is necessary to extract the enzyme from fermented cake. Thus, a study was conducted of polygalacturonase enzyme extraction, using water as solvent. The highest activity poligalacturonase 6.89 U/g was obtained under conditions of time equal to 45 minutes, rotating shaker equal to 150 rpm and ratio of solvent/mass of fermented medium equal to 5 mL/g, characterizing 35% more recovery. Factors that most influenced the process were contact time and shaker rotation. It was applied the enzyme extract obtained by solid state fermentation in tropical passion fruit juice, observing the variation of some important parameters to keep the quality. Characteristics of fresh juice vary with respect to that reported in literature, it depends on the time of harvest fruit, phenomena and agricultural practices, etc. As for checking the factors influence on process, the best results to reduction of pectin amount, about 95%, were under conditions of temperature 50°C, contact time 20 min and amount of enzyme equal to 0.05 %(v/v). There was no change in the total acidity and pH of juice after enzymatic hydrolysis. Only the empirical model for the clarity was significant with 95% confidence, taking hydrolysis temperature as a factor that influenced the process. The lowest absorbance for clarity 0.04 was achieved under the conditions: 30°C, contact time 20 min and amount of enzyme equals 0.15 %(v/v), corresponding to a reduction 98% of fresh juice clarity.