Critical storage conditions of pequi pulp microparticles and kinetics of degradation of nutritional properties

The understanding of water sorption behavior and the determination of glass transition temperature (T-g) is essential in stability studies of dried foods, to determine their best storage or processing condition. Water sorption isotherm and glass transition temperature of spray-dried pequi pulp microparticles were evaluated to obtain storage critical condition of spray dried pequi pulp, which was 25 degrees C and 62% of relative humidity (RH). Water sorption isotherm at 25 degrees C was determined by static gravimetric method, using saturated salt solutions, while T-g by differential scanning calorimetry. Total carotenoids, antioxidant capacity, lipid oxidation, and color parameters were evaluated throughout 120 days at 25 and 35 degrees C and RH of 23 and 43% to determine the powder kinetic degradation. All quality parameters presented decay during storage. Total carotenoids and antioxidant capacity by ferric reduction antioxidant power method exhibited a second-order kinetic, while antioxidant capacity by DPPH assay and lipid oxidation a first and zero-order kinetics, respectively. Both temperature and RH negatively affected nutritional properties. The storage condition that better preserved the desirable characteristics of spray-dried pequi pulp microparticles was 25 degrees C and RH of 23%. Practical Applications One of the greatest challenges for the food industry is to extend food stability against environmental factors. Especially for those food components very unstable such as pigments, antioxidant components, flavor, and so forth. The sample we used for this study was pequi fruit which has high potential in the food industry because of its sensory and nutritional qualities due to the phytochemicals present in the fruit, such as carotenoids and vitamins A and C. However, pequi is highly perishable and generally susceptible to degradation reactions. We successfully applied microencapsulation for pequi pulp protection and showed the environmental conditions that will preserve its functional properties for longer periods. Our results are relevant to extending the bioactive properties of food components.