Embalagem ativa de base biológica: filme com extrato de estigma de milho para conservação de carne bovina refrigerada

Abstract

This work aimed to investigate the best condition for extracting antioxidant and antimicrobial compounds from corn stigma and apply it as an active ingredient in bio-based films for the conservation of refrigerated beef. To obtain the bioactive extract, a 22 factorial design was proposed to investigate the influence of time and solid-solvent ratio on extraction. Ultrasound-assisted extraction of corn stigma reduced extraction time by 67% when compared to the conventional method. The ideal condition for the extraction of antioxidant compounds was with a time of 5 minutes and a solid-solvent ratio of 0.05 g mL-1. Using ESI-ToF-MS screening, it was possible to identify 27 phytochemical compounds. In addition, the results demonstrate that the extract has a remarkable antimicrobial capacity against the 23 microorganisms studied. The ideal condition was chosen to be incorporated as an active ingredient in films based on gelatin and corn starch for the conservation of refrigerated beef. The films incorporated with the corn stigma extract were successfully prepared by the casting method. The thickness and humidity of the films were not altered with the addition of the extract, but the formation of small pores on the surface was observed through scanning electron microscopy. The results also indicate that the film made with 25% extract showed a hydrophobic character, with low water solubility and strong mechanical and antioxidant properties. Corn stigma extract was found to be effective against lipid oxidation and microbiological growth in beef. The pH levels and TBARS values decreased with increasing amount of extract incorporated into the films, and the use of 25% extract allowed a 60% reduction in lipid oxidation. Likewise for the count of mesophilic and psychrotrophic microorganisms, the active film contributed to the reduction of these microorganisms after 3 days of storage. The use of extracts from plant residues as an active ingredient is an intelligent and sustainable way of valuing these agricultural by-products. Thus, corn stigma is considered a promising alternative to incorporate antioxidant and antimicrobial compounds into food packaging and improve the shelf life of beef.