Sensory and Composition Analyses of the Aqueous Phases from the Concentration of Guava (Psidium Guava L.) and Mango (Mangifera Indica L.) Juices and the Process-Induced Losses of Vitamin C

One of the major problems in the juice industry is the loss of the fruit aroma during the thermal concentration techniques. During this process, the water evaporation, which carries the volatiles, compromises the juice’s flavor. In the fruit juice concentration by vacuum evaporation, the aqueous fraction with the volatiles is composed of only one phase.This study analyses the volatiles of the aqueous fractions from the concentration of mango and guava juices in a vacuum evaporator under different temperatures. The volatiles from the aqueous fractions were analyzed using mass spectrometry and the sensorial analysis evaluated the fruit aroma intensity.Eighteen volatiles were identified in mango juice, among them, monoterpenes, sesquiterpenes and ketones were the major ones. The major compounds found in both mango juice and its aqueous fractions were 3-carene, β-pinene, β-terpinene and limonene. In the volatile profile of the aqueous fraction from the guava juice, the predominant compounds were aldehydes, such asn-hexanal and, the alcohol eucalyptol. 24 compounds were identified, including alcohols, sesquiterpenes, esters and ketones, and all characteristic volatiles were present in the guava fruit. Under the different temperature and vacuum conditions, the loss of vitamin C ranged from 35 to 77% for mango and from 15 to 55% for guava juices.Aqueous fractions collected early in the concentration under different temperatures were richer in the distinctive fruit odor when compared with the fractions collected at the end of the process. The loss of vitamin C was higher at higher temperatures and vacuum applied.