Preservation of frozen pineapple pieces through the vacuum impregnation with pectin and calcium propionate

Abstract

In this work the effect of the vacuum impregnation of pineapples pieces with pectin and calcium propionate on the preservation of the original tissues characteristics after thawing was studied. Cylinders of pineapple (3.0 cm diameter) were submitted to the vacuum impregnation with controlled pressure and with solutions of sucrose 20% added of pectin (0; 0.61; 1.5; 2.39 and 3% weight/weight) and calcium propionate (0; 1.21; 3; 4.79 and 6% weight/weight). These cylinders were frozen in static air at temperature of -20 ± 2 ºC. The vacuum impregnation time was 4 hours and a rotational central composite design was used and associated to the response surface methodology to specify the experimental conditions. Measurements of the texture, total soluble solids contents, moisture contents, cellular fluid loss (exudation) and fluid viscosity, were made before and after freezing process.  These responses were evaluated in relation to the pectin and calcium propionate concentrations and processing pressure. Results showed that for pectin concentrations around 1.5 g/100 mL of solution and increasing the calcium propionate concentration (until 6 g/100 ml of solution) is possible to get more integer structures. These results were verified by the increase in total soluble solids, lower texture loss and reduced cellular fluid loss, preserving the characteristics of frozen pineapple pieces.