Effect of Chemical Pretreatments on the Physical Properties of Kiwi

In this work the effect of pre-treatments on the physical properties of fresh kiwi was studied. For that, a set of tests using chemical pretreatments was used, in which the samples were subjected to aqueous solutions of ascorbic acid and potassium metabisulfite at concentrations of 0.25% and 1% (w/v) for periods of 30 and 60 minutes, in order to understand the implications of the treatments in the color and texture of the kiwi as compared to its original properties. The results showed that the kiwi treated with ascorbic acid changed its color very intensively when compared to the fresh product, and this trend was intensified after storage. Contrarily, when potassium metabisulfite was used, the changes in color were quite negligible right after the treatment and even lower after the storage period of 6 days under refrigeration. After the treatments with both solutions, the kiwi texture was drastically changed, diminishing hardness considerably and increasing elasticity for all treatments. The same could be observed after six days of refrigeration.

EVALUATION OF COLOUR AND TEXTURE OF A PORTUGUESE TRADITIONAL SWEET: “EGG CHESTNUT”

This work aimed to evaluate the colour and texture of a Portuguese traditional sweet “egg chestnuts” along a storage period of 12 days under refrigeration. For this, the colour coordinates were measured through a colorimeter and the textural parameters were evaluated by compression and puncture tests using a textutrometer. The results showed that the colour coordinates do not vary along time, corresponding to very low values of total colour difference. Hardness, chewiness and springiness decreased in the first 3 days but after that the values were maintained approximately constant. In contrast, resilience and cohesiveness did not change along time. While crust firmness increased along storage, both the flesh firmness and stickiness did not change. The adhesiveness measured through the penetration test decreased considerably from the first to the last day. Hence, it was concluded that colour is better preserved than texture along a 12 day storage period under refrigeration.