Instrumental and Sensory Analysis for the Design of Complex Tropical Fruit Beverage Flavorings: the Case of Soursop

Abstract

This study aimed at designing nature-identical flavorings for dairy drinks based on soursop (Anona muricata) VOCs profile, at different ripening stages, and after its processing into a fruit beverage, by combining conventional sensory analysis, and instrumental techniques: gas chromatography (GC/FID/MS) and a metal oxide (MOS)-based electronic nose. For this purpose, unripe fruits were harvested and ripened in controlled conditions while monitoring soluble solids, pH and acidity. Furthermore, ripe fruits were processed into a soursop sugary drink. Dichloromethane extracts of semi-ripe, ripe and overripe pulps, and ripe soursop drink, were analyzed by GC-FID/MS for assessing their VOCs profiles. In parallel, pulps at the same three ripeness degrees, and the soursop drink were analyzed by e-nose, in order to study changes in their aromatic profile. Fifty-two aroma compounds were identified. Terpenes were the most representative group of the semi-ripe stage, whereas esters were more predominant in the ripe and overripe pulps. A greater incidence of lactones and small-chain acids and alcohols in the latter, indicated the start of degradation. In the sugary drink, there was higher predominance of esters, whereas the relative concentration of terpenes and alcohols decreased, probably due volatilization during heat processing. E-nose showed a higher aromatic intensity in the ripe pulp, and principal component analysis (PCA) clearly differentiated the three ripening stages and the sugary soursop drink. Four nature-identical flavorings were developed according to the determined profiles. A descriptive-comparative sensory analysis of flavorings vs. their natural targets, using 13 flavor descriptors, allowed to adjust the formulations. The adjusted flavorings were added (0.08%) to a sweetened whole yogurt, and subjected to descriptive and consumer acceptance sensory tests. The perceived flavor of yogurts was successfully associated with the sensory profile of the fruits at their respective ripening/processing stage. Finally, the consumer test showed a better performance of overripe soursop-flavoring in terms of acceptance and approximation to a naturally-flavored drink, suggesting that consumers favor more complex creamy and cider notes of the overripe soursop.