Active biopolymer coating based on sodium caseinate: Physical characterization and antioxidant activity

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

Proteolytic and lipolytic starter cultures and their effect on traditional fermented sausages ripening and sensory traits

In this study, three starter formulations including Lactobacillus curvatus and Staphylococcus xylosus strains selected in vitro on the basis of their lipolytic and proteolytic activities were employed for the manufacture of traditional fermented sausages of southern Italy. Microbial population, proteolysis, lipolysis, changes in free amino acids (FAA) and free fatty acids (FFA) and development of characteristic taste and flavor of the final product were investigated. Proteolysis and lipolysis were observed in sausages inoculated with proteolytic and lipolytic S. xylosus coupled with L. curvatus, while the sausage started with only S. xylosus without lactobacilli was identical to the non-inoculated control, indicating that the proteolysis could be due to both microbial activity and endogenous proteases activated by the decrease in pH. The statistical analysis applied to the instrumental and sensory data showed that there was an effect of the starter used on the characteristics of the sausage obtained. In particular, the control samples showed very close features different from the sausages obtained by adding starter cultures. Finally, analyzing the sensory parameters the sausages ripened without starter addition and those started without the L. curvatus AVL3 showed similar features indicating an influence of the presence of the lactobacilli on the final organoleptic quality of the sausages. An appropriate choice of a combination of strains in a starter formulation is fundamental to obtain products of the expected quality

Active casein coatings and films for perishable foods: Structural properties and shelf-life extension

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

Correlation between sensory and instrumental properties of Canestrato Pugliese slices packed in biodegradable films

This paper compares the performance of three novel biodegradable films having different gas and water vapour permeabilities to the performance of a multilayer film made of polyethylene and EVOH and having high barrier properties. As model food C. Pugliese cheese was chosen. The samples were stored for 28 days and, once a week, they were analysed using sensory and instrumental tests. Sensory data showed samples packed in high permeable biodegradable film were different from fresh cut samples after only 7 days of storage, whereas the other biodegradable films having intermediate water vapour permeability allowed the cheese to keep its sensory properties unchanged for 21 days. The only film which maintained the sensory properties of cheese, with except for texture, during all the investigated time, was the high barrier film. The sensory data are confirmed by acceptability scores

Effect of biopolymer active coating on alteration kinetics of minimally processed fennel stored at different temperatures

The effect of an active coating based on sodium caseinate and propyl gallate on the physical and nutritional quality indices changes of minimally processed fennel stored at different temperatures was investigated. Pseudo-zero and pseudo-first-order models well described the quality changes of the product over time, whereas the Arrhenius-type model was used to estimate the activation energy of the alteration processes in the range of temperatures tested. The kinetic constants of the total antioxidant capacity (TAC) and vitamin C loss were reduced by 30% and 20% thanks to the presence of the coating. Whereas for the physical properties, the kinetic constants were not affected. Additionally, the TAC loss of coated samples was less sensitive to temperature change (Ea TAC 113) than the control sample (Ea TAC 130). In conclusion, sodium caseinate coating enriched with propyl gallate can be a technological solution to preserve the nutritional quality of minimally processed fennels

Novel pumpkin seed oil-based oleogels: development and physical characterization

The objective of this research was to develop novel oleogels based on pumpkin seed oil and natural waxes. Crystallization and gelation of 4, 5, 6 and 8 % of beeswax and carnauba wax in pumpkin seed oil were investigated, and their physical properties were evaluated using an oleogel prepared with sunflower oil and beeswax as reference. In order to obtain a complete three-dimensional network, after a cooling stage a setting stage was necessary at 25 °C for no longer than 60 min. Oleogels produced with pumpkin seed oil and beeswax were weaker than those made with sunflower seeds; pumpkin seed oil-based oleogels structured by carnauba wax presented higher viscoelastic properties, retained more oil and were firmer than oleogels based on beeswax. Based on scaling theory, all the oleogels followed a strong-link regime and the fractal dimension of the network (D) was comparable to fats widely used in food production. Therefore, pumpkin seed oil can be used to create novel oleogels

Use of chitosan and chitosan-caseinate coating to prolong shelf life of minimally processed apples

The effect of biopolymer coatings (1% chitosan, 2% chitosan, caseinate/chitosan blend at ratio 2/1) in combination with anti-browning agent (1% citric acid, 1% l-ascorbic acid agents, 1% CaCl2) on the shelf life of minimally processed apples was studied. The experimental works were divided in two phases: in the first phase, the coating composition has been selected on the bases of microstructural analysis of the coatings on the fruit surface (SEM), respiration rate, water resistance, and color. In the second phase of the study, the shelf life of packed minimally processed apples coated with the selected coating was studied during storage at 5 degrees C. The uncoated sample dipped in anti-browning solution was used as control. The following quality attributes were monitored after 1, 3, 7, 11 and 14 days: pH, hardness, relative humidity (RH %) and color. All coatings effectively reduced respiration rate of minimally processed apples but only caseinate/chitosan one was not significantly different from the control sample in terms of color attributes (p<0.05). Shelf life study showed that the chitosan-caseinate coating was able to extend the product shelf life from 7 days to 11 days at 5 degrees C