ABSTRACT
This study evaluated the effectiveness of phenolic compound incorporation from blueberry juice into pear slices (PS) using a combination of ohmic heating (OH) and vacuum impregnation (VI), followed by air-drying (AD) or freeze-drying (FD). Our results showed that OH increased the content of bioactive compounds and antioxidant capacity of blueberry juice, with the optimal OH condition set at 50 °C for 20 min under an electric field of 13 V·cm-1. Furthermore, the combination of VI and OH was efficient in enriching PS with bioactive compounds from blueberry juice (such as cyanidin and epigallocatechin), with the optimal VI/OH condition set at 50 °C for 90 min under an electric field of 7.8 V·cm-1. Moreover, anthocyanin pigments from blueberry juice affected the color parameters of PS by increasing the a* parameter and decreasing the b* and L* parameters. However, both FD and AD (at 40, 50, and 60 °C) negatively affected (p ≤ 0.05) the phenolic content and antioxidant capacity. Notably, AD at 60 °C showed the highest levels of phenolic compounds and antioxidant potential for both impregnated and non-impregnated PS.
ABSTRACT
Fruits are sources of bioactive compounds (BACs), such as polyphenols. This research aimed to study the in vitro bioaccessibility of polyphenols from enriched apple snacks with grape juice and determine their antioxidant capacity. Impregnation (I) treatments were carried out at atmospheric pressure and in a vacuum (IV) at 30, 40, and 50 °C and their combinations with ohmic heating (OH), I/OH, and IV/OH. Later, samples were dehydrated by forced convection at 40, 50, and 60 °C. Enriched samples were subjected to in vitro digestion. The total polyphenols, monomeric polyphenols, and antioxidant activities were determined from recovered extracts. Results showed that total polyphenols present in higher concentrations in the gastric phase, 271.85 ± 7.64 mg GAE/100 g d.m. Monomeric polyphenols' behavior during in vitro digestion for the VI/OH 50 °C and dried treatment (60 °C) was descending, mainly in quercetin, which decreased by 49.38% concerning the initial concentration, before digestion. The cyanin, catechin, epicatechin, and epigallocatechin decreased by 26.66%, 20.71%, 23.38%, and 21.73%, respectively. Therefore, based on obtained results, the IV/OH 50 °C treatment (dried 60 °C) is the best combination to incorporate polyphenols from grape juice.
