Liofilização de polpa de maracujá do mato (Passiflora cincinnata Mast.) para obtenção de produtos alimentícios.

Abstract

The aim of the present study was to obtain Crato passion fruit in powder form for food purposes, using the freeze-drying process. To obtain the Crato passion fruit (CPF) powder, seven formulations of Crato passion fruit and maltodextrin (MD) 20DE were freeze-dried at the following concentrations: FC= 100%CPF; F1= CPF + 5%MD; F2= CPF+ 10%MD; F3= CPF+ 15%MD; F4= CPF + 20%MD; F5= CPF+ 25%MD; and F6= CPF + 30%MD. The rheological behavior of the fresh fruit and its formulations at temperatures of 10ºc and 25°C were determined, as well as the kinetics of Crato passion fruit pulp freezing and its formulations at temperatures of -25ºC, -60ºC, -76ºC and – 170ºC and the freeze-drying kinetics to obtain the product in powder form in all the aforementioned formulations. In addition to the kinetic study, the fresh pulp and base formulations underwent chemical and physicochemical characterization, where, after freeze drying the powders with moisture content of less than 10%, they were submitted to physical, chemical and physicochemical characterization (pH, total soluble solids, total titratable acidity, ascorbic acid, total sugars, reducing sugars, non-reducing sugars, moisture content, Aw, solubility, wettability, hygroscopicity, optical microscopy and color), in addition to microbiological assessment. Finally, each of the powders was rehydrated producing a nectar ready to consume, at proportions of 1:0.04 (potable water: Crato passion fruit powder) with the addition of 10% sucrose, after which these formulated nectars underwent sensory analysis to determine the acceptance and intention to buy of 80 non-trained testers. The results obtained with respect to rheological behavior, Crato passion fruit and its formulations added with maltodextrin exhibited dilatant behavior, and Ostwald-de-Waelle (Power Law), Casson and Herschel-Bulkley models express the experimental data very well. In regard to freezing kinetics, the greater the concentration of maltodextrin in the formulations, the faster the freezing. All freezing kinetic curves of the samples submitted to slow and intermediate freezing, that is, at -25°C (slow) and -60ºC and -76ºC (intermediary), exhibited the three well defined freezing phases, cooling (PHASE 1), freezing or crystallization (PHASE II) and post-freezing (PHASE III) and the Fourier model using the 1st term of the series was a good representation of the freezing kinetics of fresh Crato passion fruit pulp and its formulations containing maltodextrin at temperatures of -25ºC, -60ºC, -76ºC and -170º C. The kinetics of freeze drying showed a decline in sublimation rate at lower freezing temperatures, due to porosity of the samples; the mathematical models used to describe xxi the relationship between the moisture content/freeze drying time ratio represent the experimental data well, with R2 above 98% and MSD below 1; the powders comply with legal standards for microbiological analyses; a number of physical, chemical and physicochemical traits (moisture content, total titratable acidity, water activity, wettability, apparent density, optical microscopy and color) underwent changes with an increase in the drying adjuvant maltodextrin, and the Crato passion fruit powders displayed good fluidity. Sensory analysis of Crato passion fruit nectar showed that the freeze-dried powder with 25% maltodextrin pre-frozen at -76 ºC before freeze-drying obtained the highest acceptance scores, with an average of 6.27; however all average scores were below 7.0. With respect to intention to buy, the highest average scores were for “I would definetely buy” and “I am not sure if I would buy or not”.