Texture, microstructure and volatile profile of structured guava using agar and gellan gum

Structured fruits are food products obtained by mixing fruit pulps and hydrocolloids. The objective of the work here described was the evaluation of the impact of agar and gellan gum on morphology, texture, volatile organic compounds (VOCs) release and sensory acceptance of structured guava (Psidium guajava L.) bars. The bars were made with guava pulp and agar (100%) or low acyl gellan (LA) and high acyl (HA) gum, in the proportions of LA/HA (w/w): 100/0, 75/25 and 50/50, in the total concentration of 0.75% w/v relatively to the pulp. The microstructure of the agar bars showed interconnected and loose cavities and fibers, generating by GC-MS analysis a higher number and more intense VOCs peaks. The use of LA gellan gum results in interconnected networks, with a dense and compact structure. The guava bar formulated with agar showed adhesiveness of 141.80 N/s, lower than that obtained by LA100/HA0 (214.05 N/s) and higher than LA75/HA25 (59.39 N/s) and LA50/HA50 (54.38 N/s). Consumers preferred the appearance and texture of the formulations containing agar, LA100/HA0 and LA75/HA25, with a progressive decrease in these parameters as the proportions of HA gel gum increased. It was associated with a greater release of volatile compounds to gels that presented a less compact and rigid network, allowing better diffusion of volatiles. Thus, they were perceived by consumers. Thus, the agar proved to be the most promising hydrocolloid for the formulation of structured guava fruit, since although the formed network is strong enough to guarantee good acceptance in the texture attribute, it still allows the release of compounds that are associated with the flavor of the product.