There is an urgent need to increase the food supplies to fulfil the demands of future generations as the population of the world is expected to grow beyond 10 billion by 2050. An essential component for ensuring global food security is to reduce food losses during the post-harvest stage. Active edible coatings and films are a promising sustainable preservation technology for shelf-life extension of food products by hindering decay kinetics of minimally processed fruits and vegetables (F&V), by restricting the mass transfer of moisture, aroma, or gases and carrying an active compound, such as an antioxidant or antimicrobial. Active protein-based coatings and films have the potential to extend the shelf-life of food products by decreasing their respiration rates, as they exhibit an excellent gas barrier and good mechanical properties as compared to other biopolymeric packaging. Among protein-based biopolymers, casein and its derivatives as packaging films have been extensively studied due to their low cost, complete biodegradability, and availability. Currently, there is no review study focusing on caseinate-based active coating and film, thus, this review aims to give insights on the composition, rheology, structure, and properties of caseinate-based formulations by critically discussing the results presented in the literature. A methodological approach was followed to obtain relevant literature to discuss the influence of additives on the shelf-life of F&V. Furthermore, changes in secondary structure of casein were observed after incorporation of bioactive compounds (i.e., phenolic acids). Likewise, there is a need to explore chemical interactions among bioactive compounds and biopolymer material by using in silico and laboratory trials as food additives have shown to influence the physicochemical properties of film and shelf-life of food products.
The objective of this work was to investigate the effect of sodium caseinate concentration on physical-chemical properties of coating solutions and films obtained by casting as a starting point for the development of an active coating for minimally processed fruits or vegetables. Sodium caseinate solutions at different concentrations (4%, 8%, 10%, 12%, 14%) were used as a coating system. The coating viscosity and desorption kinetic were characterized. Minimally processed fennels were coated by dipping and the liquid and dry coating thickness were estimated by assessing the amount of coating on fennel during draining as a function of solution properties (concentration and viscosity). Film obtained by casting were also characterized in terms of equilibrium moisture content, color, and water vapor permeability. The potential of using the sodium caseinate solution to obtain active coating was investigated by adding gallic acid or rosemary oil to sodium caseinate solution at 4%. The antioxidant capacity of the coating was evaluated by DPPH test. Results show that sodium caseinate solutions follow a Newtonian behavior in the range of concentration investigated and the viscosity increased as solids concentration increased, following a power law. The drying rate was in the range 0.0063–0.00107 mgH2O·mgsolids−1·min−1·m−2 as a function of sodium caseinate concentration. The average liquid and dry coating thickness on fennels were in the range 20–70 and 0.7–6.4 μm, respectively. The water vapor permeability slightly decreased as the solid concentration increased. Active coating showed good antioxidant properties.
The effect of caseinate/chitosan blend on the shelf life of minimally processed apples was studied. In the first phase of the work, the effect of the biopolymer coating on the respiration rate of the minimally processed apples was studied as function of gas composition (5%, 10%, 21% of O2 with N2 as balance at 5 °C) and temperature (5 °C, 10 °C at 5% of O2 with N2 as balance). In the second phase, the shelf life of the packed product was studied during storage at 5 °C. The gas composition (O2%-CO2%) in the package headspace, relative humidity, pH, hardness, color and antioxidant capacity of the product were monitored after 0, 1, 4, 7, 11, and 14 days. The coating effectively reduced respiration rate of the product when oxygen was over 10%. In the presence of the coating, the reduction of oxygen did not affect the respiration rate. At 5% of O2, the respiration rate decreased by 50% by changing the temperature from 10 °C to 5 °C. Shelf life study showed that the chitosan—caseinate coating was able to preserve the mechanical properties and the antioxidant capacity of the product during storage by increasing the shelf life by 7 days to 11 days at 5 °C.
Cherry tomatoes are highly appreciated for their nutritional value but remain highly perishable due to rapid respiration and senescence. This study evaluated a multi-hurdle strategy combining plasma-activated water (PAW), sodium caseinate-based edible coating, and antioxidant active packaging to preserve minimally processed (MP) cherry tomatoes stored at 1 °C, 4 °C, and 8 °C for 15 days. Quality evolution was monitored through physical, chemical, nutritional, and microbiological parameters and described using pseudo-zero- and first-order kinetic models, with temperature dependence expressed by the Arrhenius equation. The combined treatment (prototype) slowed the degradation rates of pH, titratable acidity, total polyphenols, and antioxidant capacity, as reflected by consistently lower kinetic rate constants across all temperatures. Prototype samples showed better retention of polyphenols and antioxidant capacity, particularly at 1 °C and 4 °C, without detrimental effects on visual appearance. Metagenomic analysis revealed that the multi-hurdle treatment reshaped the microbial community, reducing the relative abundance of potentially problematic taxa such as Acinetobacter johnsonii and limiting the occurrence of antimicrobial resistance (AMR) genes at the end of storage. This study provides the first integrated assessment of PAW, edible coating, and antioxidant active packaging as a synergistic multi-hurdle strategy, demonstrating their combined ability to extend shelf life while modulating the microbiome and resistome of minimally processed cherry tomatoes.
Cherry tomatoes are highly appreciated for their nutritional value, but remain highly perishable due to rapid respiration and senescence. This study evaluated the combined effect of plasma-activated water (PAW), a sodium caseinate-based edible coating, and antioxidant active packaging on the quality evolution of minimally processed (MP) cherry tomatoes stored at 1 °C, 4 °C, and 8 °C for 15 days. Samples subjected to the full treatment (PAW wash + coating + active packaging) are hereafter referred to as prototype samples, while untreated fruits served as controls. Physical, chemical, nutritional, and microbiological parameters were monitored and modelled using pseudo-zero- and first-order kinetics, with temperature dependence described through the Arrhenius equation. The combined treatment significantly reduced the degradation rates of pH, titratable acidity, total polyphenols, and antioxidant capacity, with kinetic constants up to 45% lower than those of the controls. Prototype samples better preserved polyphenol content and antioxidant capacity across all temperatures, particularly at 1 °C and 4 °C. Microbial loads were generally comparable between groups. However, prototype samples exhibited lower Enterobacteriaceae at 8 °C and higher yeast/mould counts at 4 °C and 8 °C. Overall, the multi-hurdle approach effectively slowed quality deterioration without affecting visual appearance. The kinetic modelling framework enabled reliable shelf-life prediction, highlighting the potential of combining mild, sustainable technologies to enhance the quality and safety of MP cherry tomatoes.