30G-17 |
Color changes of prickle pear juice during concentration |
A. ALVARO, Laboratorio de Investigación de Alimentos, Universidad de las Américas, Puebla, Apdo. Postal 43, Sta. Catarina Martir, Cholula, Puebla, 72820, Mexico and P. Wesche-Ebeling. Fruit juices concentrates are very valuable semifinished products used in the production of fruit juices, beverages, jams, jellies, etc. One of the main problems during concentration is the color change of the product. Color change during thermal processing has been proposed thar follows a two step mechanism, first a zero order kinetics color formation followed by a firts order color degradation mechanism. The objectives of this work were to study the color changes in juice, pulp and juice serum during the concentration process of pectic enzymes treated and untreated prickle pear pulp, to asses if color changes can be modeled by a two step mechanism and to find a method for color change eveluation. Depectinization treatments did not cause a significant increase in the initial solid content of the pulp, however, it caused a significant change in DE and a values specially at higher temperatures (55 °C). L changes in the juice followed a firts order kinectics with k=0.0034 min -1. The changes in the prickle pear pulp were small compared to those showed by the juice serum. DE changes in the juice can be described by a two step mechanism [DE=19.02(1-exp(-0.0127t))]. The areas of the serum absoprtion spectra changed around 5.5 times during concentration. The changes in color seem to be due to multiple mechanisms and were small during concentration. The magnitude of the change of serum absorption spectra were higher than those found for the other parameters and sugest that it can be used to asses the thermal damage.
Session 30G, Fruit & Vegetable Product: Processed Fruits and Vegetables
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