Dynamics of the recovery of aroma volatile compounds during the concentration of cashew apple juice (Anacardium occidentale L.)

Abstract

The objective of this study was to identify and quantify the recovery of aroma volatiles during the concentration of cashew apple juice and propose kinetic models. Fresh juice was concentrated in a thermal-siphon type evaporator, operating in a closed system at 700mmHg. The water and volatiles evaporated during concentration were recovered by condensation, generating five condensates: the first was obtained during the concentration of the juice from 10.6°Brix (fresh juice) to 12°Brix, the second from 10.6 to 14°Brix, the third from 10.6 to 19°Brix, the fourth from 10.6 to 28°Brix and the fifth from 10.6 to 40°Brix. The volatiles in the headspaces of the condensates were vacuum stripped (70mmHg) to a Porapak Q™ trap for 2h, eluted with 300μL of acetone, identified by GC–MS and quantified by external standardization. Trained judges rated the intensity of the cashew apple aroma perceived in the condensates using a 9cm scale. The major classes of volatiles present in the condensates were esters (~90% of the total mass of volatiles), followed by aldehydes (~6%) and alcohols (~3%). In the first condensate the ester (580.3μgL−1), aldehyde (39.3μgL−1) and alcohol (23.5μgL−1) concentrations were higher than in the remaining condensates, suggesting that a more efficient recovery of the volatiles important to the cashew apple aroma and flavor could be obtained when the beverage was concentrated from 10.6 to approximately 12°Brix, namely, by condensing the first 23% of the water evaporated off from the juice. The power function was the kinetic model that best fitted the recovery of the esters, aldehydes and alcohols.