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A novel active food packaging film was developed by casting a corn starch/tea polyphenol (TP)-loaded porous starch (PS, obtained by enzymatic hydrolysis) film forming solution, with the latter helping to regulate the slow release of TP. Results showed that PS had a favorable TP adsorption capacity, and the casted films had a homogeneous distribution of the formulation components. Likewise, the active films had good mechanical properties, UV barrier properties, thermal stability, and excellent antioxidant properties. The slow release of TP from the films was sustained, which is a desired characteristic for extending the protection afforded by the active film to the food under consideration. • Porous starch (PS) was prepared by enzymatic hydrolysis. • Slow-release active packaging films were developed by solution casting technique. • PS had outstanding tea polyphenol (TP) adsorption capacity. • Corn starch (CS)-PS films showed slower TP release than films made from CS alone. • All the measured properties were improved in CS-PS films compared to CS films. [ABSTRACT FROM AUTHOR]

The anthocyanin-rich litchi shell extract (LE) was mixed with the matrix to prepare active/intelligent food packaging composite films. The microstructure and properties of composite films were characterized. The results showed that the composite films incorporated with LE had texture-oriented layered, compact, uniform cross-sections. The composite films with LE showed different degrees of red. The composite films had similar water vapor transmission rates (1.62–1.65 × 10−12 g·cm/cm2·Pa·s). However, gelatin/chitosan/polyvinyl alcohol/litchi shell extract (Gel/Csa/PVA/LE) film had better UV blocking rates (0–20 %), the best tensile strength (18.6 MPa) and elongation at break (116%). When the composite films monitored for fish freshness at 4 °C (10 d) and 25 °C (3 d), the Gel/Csa/PVA/LE film had the pH sensitivity to show an obvious color change at 25 °C, 1th day. The results suggested that the Gel/Csa/PVA/LE film could be applied to intelligent food packaging film to indicate the freshness of fish. [Display omitted] • A novel active and intelligent food packaging composite film incorporated with litchi shell extract was prepared. • Litchi shell extract had excellent antibacterial properties. • Litchi shell extract had extremely high UV shielding properties. • The composite film with litchi shell extract had outstanding mechanical properties. • The intelligent packaging film with litchi shell extract could be used as pH indicator of fish freshness. [ABSTRACT FROM AUTHOR]

• The bio-based polymer film was prepared using starch-based polyol and castor oil. • The starch-based polyol generated micropores in the film, regulated early N release. • Mutual modification regulated nutrient release more accurately. • The bio-based coating material was degradable and has no toxic effect to seeds. Due to the poor controlled release ability, bio-based materials are difficult for large scale application on controlled release fertilizers (CRFs). Starch-based polyol (SP) and castor oil (CO) were mutually modified, and a cross-linked polymer film was formed on the surface of urea by in-situ reaction, which improved the slow release ability of the bio-based material. The results showed that increasing the CO ratio reduced porosity of coating and prolonged the nitrogen (N) release period, while the SP changed the high-temperature wrinkle characteristics and regulated the early N release rate. The mutual modification achieved an ultra-long release period of bio-based CRUs for 7 months. The degradation rate during nine months of bio-based coatings (5.05 %) was significantly higher than that of petroleum-based (3.74 %), and the coating was non-toxic to rice seeds. Mutual modification provided a safe and effective solution for the preparation of bio-based CRFs with long-term controlled release capability. [ABSTRACT FROM AUTHOR]

Alkali-hydrolyzed lignocellulose was liquefied into polyols by acid-catalyzed dissolution, and then cross-linked with castor oil to prepare bio-based cross-linked polyurethane. Then, bis (2-hydroxyethyl) disulfide (SS) with self-healing function was used to reduce foaming in the curing process of polyurethane coating. Afterwards, disulfide bond modified cross-linked bio-based polyurethane coating (BCSPU) was applied to controlled-release urea (CRU). The results of excitation-emission matrices indicated that SS made the coating smoother and denser and preventing the release of non-film-forming substances. Cross-linking modification technology significantly extended the controlled release longevity of CRU by 77.3%, and the self-healing modification further prolonged the nitrogen release longevity by 61.5%. In addition, modified coating materials were non-toxic to wheat seeds and easily biodegradable in the soil. Cross-linking, self-healing modified controlled-release urea has enormous application potential in sustainable agriculture. [Display omitted] • Bio-based polymer made from corn stover-derived lignocellulose and castor oil. • Two bio-based polyols regulate the precise nitrogen release of CRFs. • Thiol modification densifies the coating and reduces the impurity dissolution. • Bio-based coating materials are easily degradable and harmless to wheat seeds. [ABSTRACT FROM AUTHOR]