Resistance of industrial mango peel waste to pectin degradation prior to by‐product drying

Susceptibility of industrial mango peel waste to pectin degradation during storage at ambient conditions (25 °C, 63% relative humidity) for up to 5 h before by‐product stabilisation by drying was explored. Depending on the interim storage period in the wet state, pectins were recovered from the dried peels by hot‐acid extraction. Most important, pectin degradation during the temporary storage of the wet peels was insignificant, as revealed by yields, composition, average molecular properties, and techno‐functional quality. Hardly acetylated (DAc 2.5–4.5%), rapid‐set high‐methoxyl pectins were obtained at starch‐corrected net yields of 14.1–15.6 g hg^?1. Irrelevant de‐esterification during peel storage in the wet state was confirmed by overall uniform setting temperatures. Arabinogalactans, uniformly indicated by high molar galactose/rhamnose ratios of 13.8–16.9 mol/mol and an arabinose percentage of 9.5–14.4 mol hmol^?1 of galactose residues, affected the galacturonide contents, intrinsic viscosities, and gel strengths throughout. The wet peels, derived from widespread manual peeling in mango canning, tolerated intermediate storage for 5 h, thus facilitating by‐product stabilisation on smaller scales.     

Atmospheric CO2/CH4 permeability of EVA copolymer/SiO2 composite membrane for biogas purification

The CO₂ and CH₄ permeabilities of poly(ethylene-co-vinyl acetate) (EVA)/SiO₂ composite membrane were investigated at atmospheric pressure. The membranes were fabricated by compression molding and characterized by Fourier transformed infrared spectroscopy, differential scanning calorimetry, a universal testing machine, and a contact angle analyzer. The effect of vinyl acetate content (18–33 wt%) was evaluated for both single-gas and mixed-gas permeation systems. A non-pressurized homemade-permeation cell was used for the single-gas permeation of CO₂ and CH₄, while a tubular membrane was utilized for a continuous separation of CO₂/CH₄ mixture. CO₂ flux was readily increased (from 0.7 to 2.0 ml/m².s) with vinyl acetate content (18–33 wt%). The enhanced CO₂ permeability is attributed to the increase in polarity and also the decrease in crystallinity of the membrane. A satisfied gas separation selectivity (CO₂/CH₄) of 4.31 could be obtained from tubular membrane with 28 wt% VA content. The incorporation of SiO₂ as a filler (0.5–2.0 wt%) especially increased the membrane polarity and hence the CO₂ flux up to 6.0 ml/m².s. However, the CH₄ flux was not affected by VA and SiO₂ contents.