Carboxymethyl cellulose/poly (vinyl alcohol) based active film incorporated with tamarind seed coat waste extract for food packaging application.

Incorporating a bioactive food waste extract into biodegradable polymers is a promising green approach to producing active films with antioxidant and antibacterial activity for food packaging. Active packaging films from carboxymethyl cellulose (CMC) and polyvinyl alcohol (PVA) incorporated with tamarind seed coat waste extract (TS) were prepared by solvent casting method using citric acid as a crosslinking agent. The effect of TS content on the film properties was determined by measuring the optical, morphology, mechanical, water vapor transmission rate (WVTR), antioxidant, and antimicrobial attributes. The CMC/PVA-TS films were also tested on fresh pork. The addition of TS did not significantly affect the film structure and WVTR but it improved the mechanical and UV barrier properties. The films possessed antioxidant and antimicrobial ability against bacteria (S. aureus and E. coli). Thus, CMC/PVA packaging was successfully prepared, and the incorporation of TS enhanced the antioxidant and antimicrobial properties of the film, which extended the shelf-life of fresh pork.

Phytochemicals from twigs of Afzelia xylocarpa and their antioxidation kinetics of oxymyoglobin.

The phytochemical investigation of crude n-hexane and ethyl acetate extracts from twigs of Afzelia xylocarpa (Kurz) led to the isolation of 14 known compounds. Their structures were elucidated by spectroscopic techniques (IR, 1H NMR, 13C NMR, and 2D NMR) as well as mass spectrometry. These structures were characterized as ß-sitosterol (1), lupeol (2), vanilic acid (3), 5,7-dihydroxychromone (4), (+)-mellein (5), isoliquiritigenin (6), 7-hydroxyemodin (7), physion (8), aromadendrin (9), naringenin (10), apigenin (11), luteolin (12), chrysoeriol (13) and kaempferol (14). Compounds 4-7 and 12-13 were isolated from the genus Afzelia for the first time. The selected compounds 5, 8, 9 and 12 exhibited potent activity for antioxidation kinetics of oxymyoglobin.

Silver-doped CdS quantum dots incorporated into chitosan-coated cellulose as a colorimetric paper test stripe for mercury.

Silver-doped CdS quantum dots capped with mercaptoacetic acid were incorporated into a chitosan-coated filter paper to fabricate a colorimetric test stripe for mercury. Chitosan assisted in the stabilization of CdSAg QDs on cellulose and enhanced the analyte diffusion in the test stripe. Hg(II) ions were captured by mercaptoacetic acid on CdSAg, resulting in a visualized color change from yellow to deep brown. For enhanced sensitivity and quantitation with good reproducibility, the color intensity was recorded, transmitted to a smartphone camera and computed by the ImageJ software to provide a digital readout. The assay was rapid, simple, and selective for mercury as several potential interfering species provoked no signal response. The applicability of the sensing approach was demonstrated for the analysis of spiked Hg(II) ions in cosmetic cream with a detection limit of 124 µM. Graphical abstract Schematic of a colorimetric test stripe consisting of silver-doped CdS quantum dots coated withmercaptoacetic acid and embedded into a chitosan matrix on paper. It enables mercury(II) to be visuallyquantified even in complex matrices such as cosmetics.

Isolation of heat-tolerant myoglobin from Asian swamp eel Monopterus albus.

Myoglobin from Asian swamp eel Monopterus albus was purified from fish muscle using salt fractionation followed by column chromatography and molecular filtration. The purified Mb of 0.68 mg/g wet weight of muscle was determined for its molecular mass by MALDI-TOF-MS to be 15,525.18 Da. Using isoelectric focusing technique, the purified Mb showed two derivatives with pI of 6.40 and 7.12. Six peptide fragments of this protein identified by LC-MS/MS were homologous to Mbs of sea raven Hemitripterus americanus, yellowfin tuna Thunnus albacores, blue marlin Makaira nigicans, common carp Cyprinus carpio, and goldfish Carassius auratus. According to the Mb denaturation, the swamp eel Mb had thermal stability higher than walking catfish Clarias batrachus Mb and striped catfish Pangasius hypophthalmus Mb, between 30 and 60 (°)C. For the thermal stability of Mb, the swamp eel Mb showed a biphasic behavior due to the O(2) dissociation and the heme orientation disorder, with the lowest increase in both Kd(f) and Kd(s). The thermal sensitivity of swamp eel Mb was lower than those of the other Mbs for both of fast and slow reaction stages. These results suggest that the swamp eel Mb globin structure is thermally stable, which is consistent with heat-tolerant behavior of the swamp eel particularly in drought habitat.