Combined effect of starch/montmorillonite coating and passive MAP in antioxidant activity, total phenolics, organic acids and volatile of fresh-cut carrots

Selection of Microbial Targets for Treatments to Preserve Fresh Carrot Juice

Fresh carrot juice presents nutritional and organoleptic qualities which have to be preserved. However, it is a fast perishable beverage, and its low-acidic pH promotes the development of foodborne pathogens and spoilage microorganisms. This study aims to assess the modification and variability of physicochemical and microbial indicators during storage of carrot juice, and to isolate and select microorganisms to be used as promoters of spoilage to quantify the effect of preservation treatments. To achieve that, 10 batches of carrot Daucus carota cv. Maestro juice were prepared independently, stored up to 14 days at 4 °C and analyzed. Volatile compound composition differed mainly according to the analyzed batch. During storage, an increase of the content of ethanol, ethyl acetate or 2-methoxyphenol, which are produced by different microorganisms, was noticed. Isolation of bacteria revealed Pseudomonas, lactic acid bacteria, and enterobacteria, some of them provoking odor modification of carrot juice at 4 °C. Assays in carrot juice with isolated yeasts and molds showed the ability of Meyerozyma guillermondii to induce texture modification and some isolates, e.g., Pichia guillermondii, resulted in gas production. Selected isolates able to induce spoilage are useful to test preservative treatments of fresh carrot juice under controlled conditions.

Effect of chitosan coatings supplemented with chitosan-montmorillonite nanocomposites on postharvest quality of 'Hom Thong' banana fruit

The chitosan (CTS) solutions supplemented with chitosan-montmorillonite (CTS-MMT) nanocomposites at various concentrations were prepared for free-standing films by the casting technique. Incorporating 2% CTS-MMT nanocomposites into the free-standing CTS films could improve the water-resistance and oxygen barrier of the film. For the postharvest experiment, CTS and CTS supplemented with CTS-MMT nanocomposite solutions were applied as banana fruit coating by the dipping technique. The CTS supplemented with 2% CTS-MMT showed a significant retarding in peel color change, reduced electrolyte leakage, and MDA content, while CTS coating could maintain fruit firmness and reduce plasma membrane destruction for only the first few days. In addition, the CTS supplemented with 2% CTS-MMT coating could reduce ethylene production and respiration rate of the banana fruit. Overall results suggest that the CTS supplemented with 2% CTS-MMT nanocomposites is a novel coating material for maintaining the postharvest quality of 'Hom Thong' banana fruit.

Recent Developments in Food Packaging Based on Nanomaterials

The increasing demand for high food quality and safety, and concerns of environment sustainable development have been encouraging researchers in the food industry to exploit the robust and green biodegradable nanocomposites, which provide new opportunities and challenges for the development of nanomaterials in the food industry. This review paper aims at summarizing the recent three years of research findings on the new development of nanomaterials for food packaging. Two categories of nanomaterials (i.e., inorganic and organic) are included. The synthetic methods, physical and chemical properties, biological activity, and applications in food systems and safety assessments of each nanomaterial are presented. This review also highlights the possible mechanisms of antimicrobial activity against bacteria of certain active nanomaterials and their health concerns. It concludes with an outlook of the nanomaterials functionalized in food packaging.