Efeito da liofilização sobre a qualidade da polpa de abacate (Persea americana Mill) e elaboração de guacamole liofilizado

Abstract

The tropical climate, with high humidity and temperature, provides unfavorable conditions for the preservation of food, mainly of fruits such as avocado which is highly susceptible to natural degradation reactions. The freeze-drying has great potential to ensure the stability of the pulp of the avocado. However, it is necessary to study the parameters that influence the process, such as freezing and pressure that directly affect aspects of enzymatic browning, loss of bioactive compounds and changes in sensory characteristics of dried fruit. Thus, this study aims to evaluate the influence of variables used in the process of freeze drying on the quality of the pulp of avocado and preparation of freeze-dried guacamole. For this purpose, freezing conditions and pressure lyophilization established. The quality evaluation was done by performing physical and chemical analysis of pH, titratable acidity and total soluble solids, as well as texture analysis, microscopy, color (L *, a *, b *, C h), antioxidant activity, composition of fatty acids, phenolic acids, total phenols. Semi-empirical models and empirical were used to describe the kinetics of lyophilization and rehydration of the pulp. Analyses were performed sensory tests guacamole rehydrated by difference from the control and acceptance. The pulp of the avocado had approximate average values of 6.25 °Brix, 4.57% titratable acidity, pH 6.36, ratio of 3.7 and 17.68 gallic μgácido/mLextrato. The samples prepared guacamole with avocado pulp lyophilized (PF and PU), regardless of the type of freezing, had the best answers to all the sensory attributes studied. The type of freezing exerted great influence on the kinetics of lyophilization and rehydration of the pulp of the avocado, while the samples frozen in the freezer had a higher rate of drying and a greater flow of moisture absorption. However, the rapid freezing promoted the quality of the product, minimizing losses and damage to the nutritional compounds appeared and the product structure. All samples guacamole differ from the standard sample, but showed good sensory acceptance for all attributes studied.