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100 g -1 of calyces. The total monomeric anthocyanin content (209±21 mg . 100 g -1 ) was similar to that obtained using the HPLC technique (215±31 mg . 100 g -1 ) when extracting the calyces with the 50:50% (v/v) ethanol:water solution. The deepest red-purple (Hue = 62.50±0.34) colored solution was observed when extracting the calyces with ethanol. The antioxidant and color properties of Roselle calyces make the extracts ideal for use in foods as a natural extract, concentrate, or powder.

Chicken slabs (10.061.060.5 cm) were deep-fat fried with sunflower oil at several temperatures 130, 140, and 150 C. Moisture content and oil absorption was determined during the whole experiment, and the following properties were evaluated: sample dimensions, temperature of the geometric center of the slab, mass transfer diffusivity, thermal diffusion coefficient and heat transfer coefficient. Fourier, Newton and Fick equations were applied to obtain the correspondent physical properties; whereas, empirical relationships were generated to describe the evolution of central temperature, moisture and oil content, as well as the product dimensions: length, width and thickness, as a function of frying time at three process temperatures.

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Microwave technology for the pasteurization of fruit juices offers advantages over conventional processing methods due to volumetric heating and fast rates that result in shorter processing times. In this study, guava nectar was pasteurized by microwave heating (2450 MHz) to 90°C using 500 or 950 W. For comparison, nectar pasteurization at 90oC was performed using a plate heat exchanger (PHE) at 400 or 200 mL/min for holding times 3.1 and 12.5 s respectively. After thermal treatments, nectars were stored at 4°C and analyzed over a storage period of 12 days. Results showed a significant pectinmethylesterase inactivation. 94% of vitamin C was retained in microwave pasteurized nectar at 12th day storage for samples treated at 500 W. Rheological properties for nectar remained without significant variations during storage. Color was better preserved after microwave treatments (ΔE*= 0.69-0.75) as compared to samples processed by PHE (ΔE*= 1.84-2.75). Microbial counts remained below detectable levels throughout storage.