Development of sodium chlorite and glucono delta-lactone incorporated PLA film for microbial inactivation on fresh tomato

Polylactic acid-based microcapsules for moisture-triggered release of chlorine dioxide and its application in cherry tomatoes preservation

Polylactic acid (PLA)-based microcapsules, capable of releasing chlorine dioxide (ClO2) upon exposure to moisture, have been developed for fruits and vegetables preservation. The microcapsules were prepared by emulsion solvent evaporation, utilizing PLA as the wall material, and NaClO2 as the core material. After optimization, NaClO2 microcapsules exhibited an encapsulation efficiency of 55.75% and an average particle size of 498.08 μm. Citric acid microcapsules were prepared using the same process, but with citric acid as the core material. When the two kinds of microcapsules were mixed, gaseous ClO2 was released in a highly humid environment. The release rate could be adjusted by temperature and the ratio between the two microcapsules, and the release period could be as long as 17 days at 20 °C. With a certain amount of microcapsules placed in the package of cherry tomatoes, the decay rate and weight loss rate of the fruits were reduced by 63 % and 34 %, respectively, compared to the control group. The microcapsules also helped to maintain the good appearance, hardness, and the content of total soluble solid content and titratable acid content of cherry tomatoes. Therefore, the PLA-based microcapsules have satisfied convenience and effectiveness for application in fruit and vegetables preservation.

Kinetic Role of Reactive Intermediates in Controlling the Formation of Chlorine Dioxide in the Hypochlorous Acid-Chlorite Ion Reaction

An advanced experimental protocol is reported for studying the kinetics and mechanism of the complex redox reaction between chlorite ion and hypochlorous acid under acidic condition. The formation of ClO₂ is followed directly by the classical two-component stopped-flow method. In sequential stopped-flow experiments, the target reaction is chemically quenched using NaI solution and the concentration of each reactant and product is monitored as a function of time by utilizing the principles of kinetic discrimination. Thus, in contrast to earlier studies, not only the formation of one of the products but the decay of the reactants was also directly followed. This approach provides a firm basis for postulating a detailed mechanism for the interpretation of the experimental results under a variety of conditions. The intimate details of the reaction are explored by simultaneously fitting 78 kinetic traces, i.e., the concentration vs. time profiles of ClO₂^-, HOCl, and ClO₂, to an 11-step kinetic model. The most important reaction steps were identified, and it was shown that two reactive intermediates have a pivotal role in the mechanism. While chlorate ion predominantly forms via the reaction of Cl₂O, chlorine dioxide is exclusively produced in reaction steps involving Cl₂O₂. This study leads to clear conclusions on how to control the stoichiometry of the reaction and achieve optimum conditions to produce chlorine dioxide and to reduce the formation of the toxic chlorate ion in practical applications.

Application of encapsulated and dry-plated food acidulants to control Salmonella enterica in raw meat-based diets for dogs

There is an increasing demand for raw meat-based diets (RMBDs) for dogs, but these foods cannot be heat-pasteurized. Thus, the objective of this study was to evaluate the antimicrobial efficacy of encapsulated and dry-plated glucono delta lactone (GDL), citric acid (CA), and lactic acid (LA) when challenged against Salmonella enterica inoculated in a model raw meat-based diet (RMBDs) for dogs. Nutritionally complete, raw diets were formulated with different levels (1.0, 2.0 and 3.0% (w/w)) of both encapsulated and dry-plated GDL, CA, and LA with both the positive (PC) and the negative controls (NC) without acidulants. The diets were formed into patties of ∼100 g and inoculated with 3-cocktail mixtures of Salmonella enterica serovars, excluding the NC to achieve a final concentration of ∼6.0 Log CFU/patty. Microbial analyses were performed on the inoculated diets and survivors of S. enterica enumerated. Both encapsulated and dry-plated CA and LA had higher log reductions compared to GDL (P < 0.05). However, encapsulated CA and LA at 1.0% (w/w) exhibited higher log reductions (P > 0.05) and preserved product quality compared to the dry-plated acidulants at 1.0%. We concluded that 1.0% (w/w) of encapsulated citric or lactic acids could be successfully applied as an antimicrobial intervention in raw diets for dogs.

Triggered and controlled release of active gaseous/volatile compounds for active packaging applications of agri-food products: A review

Gaseous and volatile active compounds are versatile to enhance safety and preserve quality of agri-food products during storage and distribution. However, the use of these compounds is limited by their high vapor pressure and/or chemical instability, especially in active packaging (AP) applications. Various approaches for stabilizing and controlling the release of active gaseous/volatile compounds have been developed, including encapsulation (e.g., into supramolecular matrices, polymer-based films, electrospun nonwovens) and triggered release systems involving precursor technology, thereby allowing their safe and effective use in AP applications. In this review, encapsulation technologies of gases (e.g., CO₂ , ClO₂ , SO₂ , ethylene, 1-methylcyclopropene) and volatiles (e.g., ethanol, ethyl formate, essential oils and their constituents) into different solid matrices, polymeric films, and electrospun nonwovens are reviewed, especially with regard to encapsulation mechanisms and controlled release properties. Recent developments on utilizing precursor compounds of bioactive gases/volatiles to enhance their storage stability and better control their release profiles are discussed. The potential applications of these controlled release systems in AP of agri-food products are presented as well.