Improving the shelf life of tofu using chitosan/gelatin-based films incorporated with Pulicaria jaubertii extract microcapsules

Abstract

This study aimed to improve the shelf life of fresh tofu (FT) by applying chitosan (CH) and/or gelatin (GEL) films loaded with two concentrations of microcapsules containing Pulicaria jaubertii extract (MPE). The effect of packaging on the shelf life of FT was evaluated based on physicochemical, microbiological, and textural properties and bioactive compounds during storage for 4 days at 25 °C. In comparison with the films without MPE, the films containing MPE were more effective at extending the shelf life of FT, and those with 2 % MPE concentration achieved optimum results. The FT packaged by CH:GEL film containing 2 % MPE had a positive effect on the studied properties of FT during the storage period, with optimum values in weight loss (47.96 %), moisture content (23.09 %), pH (5.2), acidity (0.049 g lactic acid/100 g FT), hardness (1.74 N), chewiness (1.14), and cohesiveness (0.87 N) after 4 days of storage, whereas the FT packaged by CH film containing 2 % MPE showed less change in free amino acid combinations and had the lowest count of coliform (2.69 log/g FT), E. coli (1.77 log/g FT), Staphylococcus spp. (1.98 log/g FT), and total fungi (4.95 log/g FT) after 4 days of storage. The FT packaged with GEL film containing 2 % MPE showed the highest total phenolic content (2.39 mg gallic acid equivalent/g FT) and the highest scavenging values of DPPH (139.52 ± 3.45 μg ascorbic acid/g FT) and ABTS+ (228.71 ± 1.11 μg Trolox equivalents/g FT) on day 4. However, CH and/or GEL films with MPE led to the formation of high-quality films that can effectively prolong the shelf life of FT.