EFFECT OF TEMPERATURE ON REHYDRATION KINETICS, FUNCTIONAL PROPERTIES, TEXTURE AND ANTIOXIDANT ACTIVITY OF RED PEPPER VAR. HUNGARIAN (CAPSICUM ANNUUM L.)

Abstract

ABSTRACT Dehydrated peppers at 60C were rehydrated at three temperatures (20, 40 and 60C) to analyze the effect of processing temperature on rehydration kinetics and quality attributes of final products. Several empirical and diffusive models were applied to simulate rehydration kinetics. Based on statistical results (sum of square error, root mean square error and chi-square), Weibull and exponential models obtained the best fit quality for the experimental data. Water holding capacity and rehydration ratio presented a maximum and minimum value at 40C, respectively, indicating structural modifications of pepper due to thermal processing. Based on the glass transition temperature of the dried samples, it could be inferred that peppers are susceptible to structural disruption during rehydration at the three working temperatures. Increasing rehydration temperatures lead to a reduction in the pepper firmness. The radical scavenging activity showed higher antioxidant activity at high temperatures (e.g., 60C) rather than at low temperatures (e.g., 20 and 40C). PRACTICAL APPLICATIONS The main utility of this study is the appliance of diffusional, statistical and empirical models in food rehydration, which can be considered a basis for a very accurate estimation of rehydration time and the optimization of the rehydration process. The physicochemical analyses on food products can confirm that thermal processes modify the cell structure of food, reducing the rehydration ability due to cellular and structural disruption that takes place during dehydration. Also, families of most peppers are rich in antioxidants due to the presence of bioactive compounds, which are associated to reduction of biological complications such as aging, cardiovascular disease and carcinogenesis. In addition, dried red pepper var. Hungarian and other dried pepper exports from Chile have become especially important, because these products are consumed both dry and rehydrated. Major markets for these products include the U.S.A., the European community and Japan.