MADUREIRA, I. A.; http://lattes.cnpq.br/2346134759982522; MADUREIRA, Iremar Alves.
Resumo:
This study aimed to produce cactus pear in powder form by thin-layer drying in an
oven. Whole cactus pear pulp was manufactured from ripe fruit and characterized as to
total solid content, water content, total soluble solids, titratable acidity, pH, ascorbic acid,
total sugars, reducing sugars, ashes, water activity, density and color. Formulations
composed of cactus pear pulp added with modified starch at concentrations of 20, 25 and
30% were prepared. Next, thin,layers (0.5 cm thick) were placed in trays and dried in an
air-circulation oven at temperatures of 50, 60 and 70 °C. Kinetic drying curves were
determined and models proposed by Lewis, Page, Henderson & Pabis, Logarithmic and
Midilli et al. were fit to these curves. The dry samples were removed from the trays and
ground to obtain powder samples. The latter were characterized as to pH, titratable acidity,
total sugars, reducing sugars, ascorbic acid, water activity, total soluble solids, luminosity
(L*), redness (+a*) and yellowness (+b*). Powder samples were also assessed for
hygroscopic behavior, determining moisture adsorption isotherms at 20 °C and fitted the
Oswin, GAB and Peleg models to experimental data. Whole cactus pear pulp exhibited
high moisture content and water activity, low ascorbic acid content, low acidity and
elevated total soluble solid content. The different formulations were satisfactorily
dehydrated, resulting in finely-granulated powders. The Lewis, Page, Henderson & Pabis,
Logaritmico and Midilli et al. models fit well the experimental data, and can be used to
predict drying kinetics. The model that best fit experimental data with respect to moisture
adsorption isotherms of the powder samples was that proposed by Peleg. Depending on
formulation and drying temperature, moisture adsorption isotherms were classified as type
I or I I . Total soluble solids, as well as total and reducing sugars of the powder samples
were not influenced by drying temperature or starch concentration. Furthermore, they
exhibited low ascorbic acid content and were considered low-moisture foods (aw < 0.60).