Inhibition of Listeria monocytogenes in Fresh Cheese Using Chitosan-Grafted Lactic Acid Packaging

Contribution of polysaccharides from crustacean in fermented food products

Fermented foods are of great importance for their role in preserving nutrients and enriching the human diet. Fermentation ensures longer shelf life and microbiological safety of food. Natural bioactive compounds have been paid attention as nutraceuticals or functional ingredients, which have health-promoting components since polysaccharides, especially chitosan, chitin and their derivatives, are biocompatible and biodegradable, biorenewable, without toxic properties and environmentally friendly. They have been applied in several fields such as medicine, agriculture, and food industry. This chapter provides information on polysaccharides obtained from crustacean as bioactive compounds as well as their effects in fermented foods.

Cross-Linking Chitosan into Hydroxypropylmethylcellulose for the Preparation of Neem Oil Coating for Postharvest Storage of Pitaya (Stenocereus pruinosus)

The market trend for pitaya is increasing, although the preservation of the quality of this fruit after the harvest is challenging due to microbial decay, dehydration, and oxidation. In this work, the application of antimicrobial chitosan-based coatings achieved successful postharvest preservation of pitaya (Stenocereus pruinosus) during storage at 10 ± 2 °C with a relative humidity of 80 ± 5%. The solution of cross-linked chitosan with hydroxypropylmethylcellulose with entrapped Neem oil (16 g·L^-1) displayed the best postharvest fruit characteristics. The reduction of physiological weight loss and fungal contamination, with an increased redness index and release of azadirachtin from the microencapsulated oil, resulted in up to a 15 day shelf life for this fruit. This postharvest procedure has the potential to increase commercial exploitation of fresh pitaya, owing to its good taste and high content of antioxidants.

The Influence of Accelerated UV-A and Q-SUN Irradiation on the Antibacterial Properties of Hydrophobic Coatings Containing Eucomis comosa Extract

The purpose of this research was to examine the antimicrobial properties against Gram-positive bacteria, as well as the water vapour characteristic of polylactic acid (PLA) films covered with a methyl⁻hydroxypropyl⁻cellulose (MHPC)/cocoa butter carrier containing Eucomis comosa extract as an active substance. The second purpose of the study was to evaluate the influence of accelerated UV-A and Q-SUN irradiation (UV-aging) on the antimicrobial properties and the barrier characteristic of the coatings. The results of the study revealed that MHPC/cocoa butter coatings had no influence on the growth of Staphylococcus aureus, Bacillus cereus, and Bacillus atrophaeus. MHPC/cocoa butter coatings containing E. comosa extract reduced the number of bacterial strains. MHPC/cocoa butter coatings also decreased the water vapour permeability of PLA. It was shown that accelerated UV-A and Q-SUN irradiations altered the chemical composition of the coatings containing cocoa butter. Despite the alteration of the chemical composition of the layers, the accelerated Q-SUN and UV-A irradiation had no influence on the antimicrobial properties of E. comosa extract coatings against S. aureus and B. cereus. It was found that only Q-SUN irradiation decreased the coating activity with an extract against B. atrophaeus, though this was to a small degree.