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Background To establish bioplastics as a real alternative to conventional plastics, high production costs must be constrained by using different kinds of wastewater streams as organic substrates and novel microbial strains as material-accumulating bacteria with high performance. Volatile fatty acids (VFAs) from the effluent of dairy wastewater biodigestion represent a new and inexpensive feedstock, which was used in this study for biopolymer production through microbial processes. Results Cupriavidus necator DSM 13513 was particularly able to accumulate PHAs when operating in fed-batch mode by limiting the oxygen level together with intermittent feeding of a carbon source; maximum poly-β-hydroxybutyrate (PHB) accumulation was achieved in 48 h without compromising microbial growth. The complex VFAs mixture from the digestate did not influence PHA homopolymer accumulation. In fact, structural characterization by NMR analysis revealed PHB synthesis by C. necator DSM 13513 grown with different VFAs mixtures. Moreover, the bioplastic disk obtained from C. necator DSM 13513 cells grown on VFAs from digested dairy wastewater effluent presented good thermic properties and low affinity to water. Conclusions Overall, the results make digested dairy wastewater effluent suitable for PHB production for specific biobased industrial applications.

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&ndash, 0.00107 mgH2O&middot, mgsolids&minus, 1&middot, min&minus, m&minus, 2 as a function of sodium caseinate concentration. The average liquid and dry coating thickness on fennels were in the range 20&ndash, 70 and 0.7&ndash, 6.4 &mu, m, respectively. The water vapor permeability slightly decreased as the solid concentration increased. Active coating showed good antioxidant properties.

Minimally processed F&V while being as fresh as the intact product, are characterized by an accelerated produce decay which affects its nutritional value during shelf-life. In this sense, food processing needs to further evolve in terms of better preservation of nutritional properties. Active packaging technology has shown positive and promising results to maintain safety and sensory properties of minimally processed F&V. This review aims to present the recent research results regarding biopolymeric antioxidant film and coating for preservation of nutritional quality of minimally processed F&V. The mechanism by which nutritional losses (around 5–30 % loss of ascorbic acid and phenolic compounds) occur from oxidation reactions in F&V and natural antioxidant have been discussed. Furthermore, regulatory aspects related to antioxidant packaging have been also reported. Biopolymers based antioxidant film and coating have been vastly used to pack F&V product. Chitosan, gelatin, casein and alginate were found to be more effective as packaging materials (both as coating and as film) to preserve the nutritional and sensory quality of F&V product. Furthermore, plant extracts (green tea and Aloe vera), essential oils (lemon grass), plant oil compounds (eugenol and citral) and phenolics (thymol) as a component of active film or coating systems have shown promising results in preserving the quality of fresh produce. The collected findings will be useful to accurately design an innovative active film or coating for nutritional quality preservation of minimally processed fresh fruits and vegetables.

New antioxidant polyamide was prepared by total immersion in active extract for 48 h. Its antioxidant performance was tested using DPPH (IC50 = 270 ± 21 μg/g) and ORAC (1.52 µmol Trolox/g). In vivo study was done using fresh minced meat stored at 4 °C and analysed after 0, 6, 13, 19, 23 days. After 23 days metmyoglobin (MetMbBK = 31.3 ± 2.9% and MetMbAOX = 25.9 ± 0.8%), CIE L*a*b* (a*BK = 15.0 ± 0.4 and a*AOX = 16.6 ± 0.3) and TBARS (MDABK = 0.0060 ± 0.0003 µg/g and MDAAOX = 0.0044 ± 0.0002 µg/g) showed an improvement of meat shelf life. The results showed that this active film protected meat during 23 days. Migration study to food simulants was done by UPLC®-QqQ-MS and UPLC®-ESI-Q-TOF-MSE. A decrease of oligomers migration (for caprolactam n = 3: BK = 0.050 ± 0.004 mg/Kg; AOX = 0.019 ± 0.001 mg/Kg) was found. Industrial relevance Nowadays, food industry is focused on improving shelf life of products by controlling its lipid oxidation using natural antioxidants. The obtained results let us design a new active packaging based on natural antioxidants for extending the shelf life of fresh minced meat at industrial scale.

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 &deg, C) and temperature (5 &deg, C, 10 &deg, 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 &deg, 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 &deg, C to 5 &deg, C. Shelf life study showed that the chitosan&mdash, 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 &deg, C.

The objective of the work was to study the viability and antimicrobial activity of bacteriocin-producing lactic acid bacteria (LAB) incorporated into whey protein/inulin/gelatine (WP) edible films in presence or absence of nutrient (modified MRS broth). Moreover, the role of the cell on the film structure and properties has been investigated. The results of the work showed that WP-based films were able to ensure a high viability of the bacteriocin-producing strain L. curvatus 54M16 during 28 days of storage at 4 °C. The addition of nutrient in the film matrix slightly affected the viability of the cells, but it was critical for the antimicrobial activity of the films. Films in presence of nutrient showed a good antimicrobial activity against L. innocua C6 as in vitro system as on cooked ham. The presence of LAB has a significant effect on the structure of the film: it reduced the viscosity of the film forming solution and improved the elasticity and the percentage of elongation. Whereas, no effect was observed for water vapour transmission rate and solubility. Thus, WP-based films in presence of modified MRS broth can be used as effective delivery and carrier systems for lactic acid bacteria to develop bioactive edible film or coating with antimicrobial properties.