Secagem e liofilização de manga: características físico-químicas e sensoriais.

Abstract

Mangoes sliced up into sticks underwent two different drying methods: one of which (lyophilization), was under a freezing temperature of 24° C; the other one was the hot, conventional drying method, under 55° C, into a gas dryer Polidryer PD-25, disposed in trays. Their physical-chemical characteristics (reducing sugars, total sugars and not-reducing sugars, acidity, water text, pH, activiry of water (28° C), leached ashes, total solids and soluble solids) were analyzed in each one of these processings and also in the mango "in natura"; the microbíological (moulds, leavenings, staphylococci, and fecal coliforme); and the sensorial ones (appearance, color, aroma and taste) of the dry fried mangoes. The equations proposed by Cavalcanti Mata, Page and Thompson were used to adjust the data of the drying of dried mangoes by means of 7.0 computer Statistica, by using non-linear regression analyses wifh the Rosenbrock-Quase-Newton numeric method. The sensorial evaluation was carried out by means of the ASSISTAT 7.3 Beta computer program, applying a variance analysis, according to a factorial treatment. The experimental delineation used for the physical-chemical characterization of the mango in each of the processings was entirely performed with 03 treatments and with three repetitions (Tl - "in natura", T2 - after lyophilization, T3 - after drying under 55° C). The values that showed a signiftcant average difference were complemented with the Tukey test, at a 5"% levei (p = 0,05) or at 1% (p= 0,01) probability. Considering the results obtained we concluded that, considering the physical-chemical characteristics, that ali the analyses were signifícant at a 1% levei. The quantities of the reducing sugars, of total sugars and not-reducing sugars and the acidity were higher in the lyophilized mango; as regards the pH and the leached ashes there was no noticeable difference between the two products and the Brix was higher in the dried mango. The microbíological analyses certify that the mangoes are well within the pre-established standards for consume, presenting 1 x IO3 UFC/g of moulds and leavenings in the lyophilized mango and the absence of coliformes and staphylococci in the dried mango. As regards the sensorial characteristics, the lyophilized mango had a better appearance whereas the dried mango had a better color, taste and aroma, with a ste average corresponding to "I slightly liked it" in the hedonic scale, whereas the lyophilized mango reached a 6 average, which corresponds to "I liked it more or less". As to the drying curves the equation that best suited the experimental data of the drying of mangoes was that proposed by Cavalcanti Mata with a R2 - 99, 83% average.