Protective Effect of Alginate Microcapsules with Different Rheological Behavior on Lactiplantibacillus plantarum 299v.

Alginate encapsulation is a well-known technique used to protect microorganisms from adverse conditions. However, it is also known that the viscosity of the alginate is dependent on its composition and degree of polymerization and that thermal treatments, such as pasteurization and sterilization, can affect the structure of the polymer and decrease its protection efficiency. The goal of this study was to evaluate the protective effect of encapsulation, using alginates of different viscosities treated at different temperatures, on Lactiplantibacillus plantarum 299v under in vitro gastrointestinal conditions and cold storage at 4 °C and -15 °C, respectively. Steady- and dynamic-shear rheological tests were used to characterize the polymers. Thermal treatments profoundly affected the rheological characteristics of alginates with high and low viscosity. However, the solutions and gels of the low-viscosity alginate were more affected at a temperature of 117 °C. The capsules elaborated with high-viscosity alginate solution and pasteurized at 63 °C for 30 min provided better protection to the cells of L. plantarum 299v under simulated gastrointestinal and cold storage conditions.

Effect of chia mucilage addition on oxidation and release kinetics of lemon essential oil microencapsulated using mesquite gum - Chia mucilage mixtures.

Lemon essential oil (LEO) emulsions were prepared using mesquite gum (MG) - chia mucilage (CM) mixtures (90-10 and 80-20 MG-CM weight ratios) and MG as control sample, LEO emulsions were thenspray dried for obtaining the respective microcapsules.LEO emulsions were analyzed by mean droplet size and apparent viscosity, while microcapsules were characterized through mean particle size, morphology, volatile oil retention (≤51.5%), encapsulation efficiency (≥96.9%), as well asoxidation and release kinetics of LEO. TheLEO oxidation kinetics showed that 90-10 and 80-20MG-CM microcapsules displayed maximum peroxide values of 91.6 and 90.5 meq hydroperoxides kg-1 of oil, respectively, without significant differences between them (p > .05).MG-CM microcapsules provided better protection to LEO against oxidation than those formed with MG; where the oxidation kinetics were well adjusted to zero-order (r2 ≥ 0.94).The LEO release kinetics from microcapsules were carried out at differentpH (2.5 and 6.5) and temperature (37 °C and 65 °C) and four mathematical models (zero-order, first-order, Higuchi and Peppas) were used to evaluate the experimental data; the release kinetics indicated that the 80-20 MG-CM microcapsules had a longer delay in LEO release rate, followed by 90-10 MG-CM and MG microcapsules, hence, CM addition in MG-CM microcapsules contributed to delay the LEO release rate. This work clearly demonstrates that use of a relatively small amount of CM mixed with MGimproves oxidative stability and delays the release rate of encapsulated LEO regarding MG microcapsules, therefore, MG-CM mixtures are interesting additives systems suitable for being applied in food industry.

Sorption isotherms, thermodynamic properties and glass transition temperature of mucilage extracted from chia seeds (Salvia hispanica L.).

Freeze-dried chia mucilage adsorption isotherms were determined at 25, 35 and 40°C and fitted with the Guggenheim-Anderson-de Boer model. The integral thermodynamic properties (enthalpy and entropy) were estimated with the Clausius-Clapeyron equation. Pore radius of the mucilage, calculated with the Kelvin equation, varied from 0.87 to 6.44 nm in the temperature range studied. The point of maximum stability (minimum integral entropy) ranged between 7.56 and 7.63kg H2O per 100 kg of dry solids (d.s.) (water activity of 0.34-0.53). Enthalpy-entropy compensation for the mucilage showed two isokinetic temperatures: (i) one occurring at low moisture contents (0-7.56 kg H2O per 100 kg d.s.), controlled by changes in water entropy; and (ii) another happening in the moisture interval of 7.56-24 kg H2O per 100 kg d.s. and was enthalpy driven. The glass transition temperature Tg of the mucilage fluctuated between 42.93 and 57.93°C.