Regina Kitagawa Grizotto

Estudo da vida-de-prateleira de fruta estruturada e desidratada obtida de polpa concentrada de mamão

The restructured fruit made with concentrated papaya pulp (700 g/kg), sugar (340 g/kg), sodium alginate (7 g/kg), low methoxy pectin (7 g/kg) and glycerol (50 g/kg), cut in a solid cylindrical form (volume approx. 2 cm3), dehydrated (12% humidity) and covered with icing sugar, was chosen for the shelf life studies. The physical, chemical, sensory and microbiological analyses were made on the product packaged in a multi layer film and stored at 0, 25 and 35 °C, for 120 days to check for quality loss. The results showed that the firmness (TA.XT2 Texturometer) and the subjective evaluations of texture and overall quality were the evaluation that best explained the quality loss of the restructured fruit during storage. Under accelerated conditions (35 °C) the product was considered adequate for consumption for up to 56 days, when it reached 4.5 (neither liked nor disliked) from the overall quality scale of the sensorial test. The kinetic values, Ea= 19,89 kcal/mol and Q10= 3, established using accelerated shelf life testing, allowed for the estimation of a shelf life of 168 days for the product at 25 °C. Under normal storage conditions, the shelf life of the product being estimated as 154 days based on the overall quality using the sensory results.

Otimização via metodologia de superfície de respostas dos parâmetros tecnológicos para produção de fruta estruturada e desidratada a partir de polpa concentrada de mamão

The objective of this study was to investigate the relevant technological parameters of the manufacturing process of restructured fruit made from concentrated papaya pulp (16oBrix) using an experimental delineation method associated with the Surface Response Methodology. The results of the Central Composed Design utilized show that the effect of the variables pectin (x1) and alginate (x2) on the increase in firmness of the papaya fruit restructured is statistically significant. A series of experiments was conducted to confirm the values predicted by the mathematical model proposed for firmness. The restructured fruits produced with the lowest addition levels of pectin (7g/kg) and alginate (7g/kg) exhibited high firmness values of about 3.2kg. These values were approximately 2.4 times greater than the values for firmness predicted by the model, probably due to variations in the pH of the papaya pulps used in the experiments. The results showed that it is possible to manufacture restructured fruit using high levels of concentrated papaya pulp (672g/kg) and minimum amounts of sucrose (364g/kg). Glycerol (x3) used at the concentration of 100g/kg reduced the level of water activity of the concentrated papaya pulp gels to 0.922. Vacuum drying (60oC/6h; 0.8kgf/kg) of the restructured fruits minimized the problem of surface adhesion and, at the same time, lowered water activity to intermediate levels of about 0.860.

Efeito da fermentação na qualidade de "chips" de mandioca (Manihot esculenta Crantz)

It was investigated the effect of natural fermentation of cassava, alone or combined with cooking in boiling water on the crispness of cassava chips. The thin slices of cassava, originally from previously peeled and cleaned roots were submerged in drinkable water at 30oC during periods of 8h and 24h. The whole cassava roots, also peeled and cleaned were submitted on the same conditions, but for longer periods: 24h, 30h and 48h, after those roots were sliced and fried. The natural fermentation was conducted without any fermentative agent, only submerging one part of thin slices or whole roots into four parts of drinkable water at 30oC in a controlled temperature incubator. The other variables studied were: cassava variety and slice format. The effect of the treatments was evaluated, based on the friability of the chips as measured by the Texture Analyzer TA.XT2. The format of the slices appeared to be an important factor, because it affected texture characteristics of the chips, as well as the actual treatments. The rectangular format, although attractive, was considered inadequate for the manufacture of chips, the round format being suggested as more suitable. It was shown that the natural fermentation of the whole roots or cut into thin slices, alone or combined with boiling was considered an inadequate technique to obtain crispness cassava chips, since in general, such treatments increased the hardness of the chips, as compared to the untreated samples. This observations were valuable from all the studied varieties: IAC Mantiqueira, IAC 576.70, IAC 13 and IAC 14.

Efeito de enzimas de maceração na textura do palmito (Euterpe edulis Mart)

With the aim of amplifying the utilization of the palm tree the influence of poligalacturonase and macerating enzymes on the texture of the hard tips of hearts of palm was studied, incubating commercial preparations of cellulase , hemicellulase and poligalacturonase with the hearts of palm, prepared as small stalks of 1-3 cm length and with 2 cm portions of the rachis of the plant. Although the treatments containing hemicellulase and a mixture of hemicellulase and poligalacturonase promoted a slight softening of the hearts of palm, the results generally showed a hardening of the texture of the hearts of palm prepared as stalks of 1 to 3 cm indicating great solubilization of the parts susceptible to hydrolysis, the hard lignin rich parts remaining intact. As in the other tissue of the plant, in the rachis of the fibrous hearts of palm, the action of the enzymes was not statiscally proven.