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The aim of the present study was the isolation of high exopolysaccharide (EPS) producers, Lactic Acid Bacteria (LAB) strains, from three types of milk: goat, sheep, and camel milk. Among 112 LAB isolates tested for their ability to produce EPS on MRS-sucrose agar, only 11 strains were able to produce EPS and only three higher producers' strains were identified by 16S rRNA gene sequencing as two strains of Lactococcus lactis subsp. lactis (SP255, SP257) isolated from camel milk and one strain of Weissella cibaria (SP213) isolated from goat milk. The physicochemical characterization of the purified EPSs revealed a significant sugar yield, with concentrations ranging from 2.17 to 2.77 g/L, while the protein content remained relatively low (0.03 g/L). The UV-visible spectrum showed high Ultra Violet (UV) absorption at 240–280 nm and the Fourier-Transform Infrared (FTIR) spectra showed the presence of a large number of functional groups, including hydroxyl (-OH), carbonyl (-C=O), and methyl groups (-CH3). The EPS solubility indicated their hydrophilic properties and the investigation of interfacial properties indicated that these EPSs could be used as natural emulsifiers and stabilizers in both acidic and neutral emulsions. Moreover, a new type of emulsion system was developed by the utilization of EPSs in the formation of multilayer interfaces in oil-in-water (O/W) emulsions stabilized by sodium caseinate (CAS). Thus, the impact of an EPS addition on the particle size distribution and electrical charge has been studied. At pH 3, the studied EPSs adhered to the surfaces of caseinate-coated droplets and the stability of O/W emulsions was improved by adding certain concentrations of EPSs. The minimum concentration required to stabilize multilayer emulsions for EPSs SP255, EPS SP257, and EPS SP213 was 1.5, 1.5, and 1.7 g/L, respectively. These findings reveal a new EPS with significant potential for industrial use, particularly as an emulsion stabilizer. [ABSTRACT FROM AUTHOR]

Multi-layer biodegradable active packaging is a new class of innovative food packaging containing bioactive compounds that are able to maintain food quality and extend shelf life preservation by releasing an active agent during storage. In this context, this study aims to develop and characterize three-layer biodegradable active films: 2 outer layers of ethylcellulose (EC) and a layer internal pectin containing nanoemulsions (NE) of trans-cinnamaldehyde (TC) as an antimicrobial agent. Trans-cinnamaldehyde (NE) nanoemulsions were prepared with soy lecithin as an agent. emulsifier to stabilize the TC and protect it for the duration of the film manufacturing. The average size and the zeta potential of the nanoemulsion droplets were 103.93 nm and -46 mV, respectively. The opacity of samples of monolayer and multilayer films decreased by 15.19 (A*mm-1) for the monolayer film of pectin incorporated by nanocapsules at 2.02 for multilayer films. In addition, the multilayer technique has made it possible to improve the mechanical properties of the films compared to monolayers with greater resistance breakage and greater extensibility. Inhibition tests on four bacteria representatives of bacteria pathogens and spoilage found in food industries have confirmed the antimicrobial activity, both, mono and multilayers. The work presented in this study offers perspectives for the fabrication packaging based on antimicrobial and biodegradable multilayer films.

In this study, an antimicrobial plant-based film was developed using pectin which is incorporated by different percentages of nanoemulsified trans-cinnamaldehyde (TC). The nanoemulsion of TC was incorporated into pectin to form films containing TC at concentrations of 5.00%, 3.33%, 2.50% and 2.00% (w/w). The nanoemulsion of TC was formed by using soybean lecithin as an emulsifier and had a zeta potential of −57 mV and an average size of 106 nm. The analysis showed that the addition of emulsified TC enhanced the light barrier properties, but the opacity of films increased due to the increase in light absorption, coalescence, and light-scattering phenomena. Films containing the nanoemulsion of TC exhibited reduced tensile strength and elasticity due to structural discontinuities in the film network caused by the presence of the nanoemulsion of TC, while elongation at break increased for TC concentrations of 2.50% and 2.00%. The films retained their infrared spectra, but their thermal stability decreased slightly. The incorporation of TC nanoemulsion significantly reduced the glass transition temperature, as shown by the differential scanning calorimetry analysis. The active films showed antimicrobial activity against Listeria innocua and Escherichia coli, indicating their potential for various food applications. [ABSTRACT FROM AUTHOR]