RESUMEN
Chicken fillet is a suitable medium for growth and activity of different types of microorganisms. The pH and nutrients content of fillets are the most important factors in their microbial spoilage and degradation during cold storage at the retail level. In this regard, the uses of edible coatings containing antimicrobial and antioxidant compounds are effective approaches to maintain the quality of fillets. In this study the inhibitory effect of edible coating materials based on chia seed mucilage containing 0.00%, 0.25% and 0.50% zinc oxide nanoparticles (ZnO-NPs) on microbial growth and chemical spoilage as well as enhancing shelf life of chicken fillets during refrigerated storage for 20 days was investigated. The results of X-Ray diffraction confirmed the dispersion of ZnO-NPs on the chia seed mucilage matrix. Also, the number of total aerobic mesophilic and psychrophilic bacteria, coliforms and lactic acid bacteria, and the pH, total volatile nitrogen, peroxide and free fatty acids indexes in the control fillets were significantly increased compared to the fillets coated with chia seed mucilage during storage. While, in the samples coated with chia mucilage containing ZnO-NPs the number of the above-mentioned bacteria decreased in the first stage and then significantly increased during storing. Based on our findings, the shelf life of fillets could be increased at least 20 days by coating them with the chia seed mucilage containing ZnO-NPs.
RESUMEN
This study was aimed at optimizing the astaxanthin extraction efficiency from shrimp shell (green tiger, Penaeus semisulcatus). Astaxanthin was extracted using selected nonpolar/polar solvents (petroleum ether, n-hexane, ethanol, acetone) individually and in ternary mixtures of petroleum ether, acetone, and water in ratios of 15:50:35, 50:45:5, and 15:75:10 for different times (2,4 and 6 h). The results showed that solvents with higher polarity were more suitable for the extraction of astaxanthin, and increasing the extraction time from 2 to 6 h improved the extraction yield. The conditions of extraction of astaxanthin with the desirable solvent were then optimized with the ultrasonic method using the Box-Behnken design [variables included: extraction temperature (25 to 45 °C), extraction time (5 to 15 min), and ultrasound amplitude (20 to 100%)]. Optimal extraction conditions were determined as the ultrasonic amplitude of 23.6%, extraction time of 13.9 min, and extraction temperature of 26.3 °C. Under this optimum condition, the amount of astaxanthin, ferric reducing antioxidant power, and free radical scavenging capacity of the extract were obtained as 51.5%, 1705 µmol of Fe2+/g, and 73.9%, respectively. Extraction and analysis of the extract at the optimum point were used to validate the results.