Encapsulation of Aroma and Off-Flavor Compounds into Preformed "Empty" V-Type Starch

Abstract

Starch consists of two homopolymers of glucose, including amylose and amylopectin. The amylose component has been found to be able to form inclusion complexes with a wide variety of small molecules that could control the release and retention profiles of guest compounds. Inclusion complex between starch and aroma/flavor has attracted more attention in recent years due to its ability to reduce evaporation, to prevent volatile loss, and to enhance stability during storage and application. The main objective of this research was to determine the potential of preformed "empty" V-type starch to encapsulate aroma and off-flavor compounds and structure-complexation ability relationship in starch inclusion complexes prepared with aroma and/or off-flavor compounds. In addition, this study also aimed to investigate consumers' purchase intention of food products deodorized by "empty" V-type starch. First, novel "empty" V-type method was employed to prepare the inclusion complex between three types of "empty" V-type starches and six aroma compounds. All three types of starches presented ability to form inclusion complex with selected aroma compounds. Both starch type and aroma compounds' chemical structures were shown to significantly affect the complexation process and physicochemical properties of the formed inclusion complexes, including crystalline characteristics and thermal properties. In addition, the same approach was utilized to prepare inclusion complex between three types of "empty" V-type starches and a cyclic aroma compound, thymol, at two different concentrations. Besides starch type, aroma's concentration was also found to significantly influence inclusion complexes' properties. Among all, V6h inclusion complex prepared at a starch/thymol ratio of 5:1 and 2:1 showed the highest encapsulation efficiency and loading efficiency, respectively. All inclusion complexes displayed potent aroma retention ability, which preserved more than 70% of thymol after 8-hour of heat treatment. In addition, the "empty" V-type starch had also been examined for its ability to mask the off-flavors found in soy milk. Among all, gas phase approach was more effective approach to scavenge beany off-flavors compared to direct contact approach, and V6h-type starch was the most effective type of starch to mask all the tested beany off-flavor compounds. Lastly, consumers' willingness-to-purchase of "empty" V-type starch deodorized soy milk was further examined to determine the factors that could affect consumers' food choice. The survey results showed that sensory quality, environmental concern, and gender were significantly associated with consumers' purchase intention of "empty" V-type starch processed soy milk. Moreover, more than 80% of the participants' attitudes toward "empty" V-type starch was positive and they thought it is an interesting approach and looking forward to the launching of the real products. In combination of the potent encapsulation efficiency, aroma preservation capability, and moderate consumers' purchase intention, the V6h-type starch could be a potential aroma delivery and/or off-flavor masking material, that could be further applied into food formulations. Future research is warranted to explore the inclusion complexes' release behavior under various parameters, such as different temperature, storage, and pH conditions, that could encounter during food processing. In addition, factors that could further improve the encapsulation efficiency of inclusion complexes should be examined, and sensory profiles of the "empty" V-type starch processed food products could also be evaluated.