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An intelligent indicator film was prepared with chitosan (CS) and sodium alginate (SA) as film-forming material with added black apple peel anthocyanin (BAA). The effects of different concentrations of BAA on the microstructure, thickness, color, mechanical properties, moisture content, and ultraviolet (UV) transmittance of the composite film were analyzed and compared. In addition, the feasibility of applying the composite film for monitoring shrimp freshness was studied. The results showed that addition of BAA made the components of the composite film interact with each other. BAA was well dispersed in the composite film, which significantly improved the mechanical properties of the composite film, and reduced its water content and UV transmittance. Furthermore, the color of BAA changed from red to yellow in the pH range of 1–14, which showed an obvious respond to pH. The composite film containing 15% BAA was sensitive to pH and thus could be used for monitoring shrimp freshness. On the 5th day of storage at 4 ℃, the total volatile basic nitrogen (TVB-N) content and pH of shrimp exceeded the spoilage threshold, indicating shrimp spoilage, and the color of the film changed from red to dark gray. Therefore, CS-SA composite films can be used as a good carrier for BAA to prepare an intelligent indicator film for shrimp freshness monitoring.

Summary: A high‐glycaemic index diet can lead to elevated blood glucose levels and chronic diseases. In this study, Dictyophora indusiata powder, oats powder and Polygonatum kingianum powder were substituted for some wheat flour to make pizza crust. The aim was to investigate the effects of the three powders on the chemical composition, physical quality, antioxidant properties, in vitro digestibility of starch and sensory characteristics of pizza crust. The addition of the three powders enhanced the nutritional value of the pizza crust, especially the dried Dictyophora indusiata flour and oats powder were rich in dietary fibre and protein, the three powders also increased the total phenolic content (214%) and antioxidant activity (ABTS+185%, DPPH30.5%) of the pizza crust and improved the shelf‐life of the pizza crust. In addition, the three powders increased the slowly digestible starch (25.9%) and decreased the reducing sugar levels and hydrogenation index, and expected glycaemic index of the pizza crust compared to the control group. The results suggest that the three powders could be used as functional ingredients to enhance the nutritional value and lower the glycaemic index of pizza crusts. This study provides new ideas for the development of nutritious and hypoglycaemic functional bakery products. [ABSTRACT FROM AUTHOR]

The aim of this study was to prepare a novel pH-sensitive smart film based on the addition of purple garlic peel extract (PGE) and TiO2 nanoparticles in a sodium alginate (SA)/polyvinyl alcohol (PVA) matrix to monitor the freshness of beef. FT-IR spectroscopy revealed the formation of stronger interaction forces between PVA/SA, PGE, and TiO2 nanoparticles, which showed good compatibility. In addition, the addition of PGE improved the tensile strength and elongation at break of the composite film, especially in different pH environments, and the color response was obvious. The addition of 1% TiO2 nanoparticles significantly improved the mechanical properties of the film, as well as the light barrier properties of the film. PGE could effectively be uniformly dispersed into the composite film, but it also had a certain slow-release effect on the release of PGE. PGE had high sensitivity under different pH conditions with rich color changes, and the color showed a clear color change from red to yellow-green when the pH increased from 1 to 14. The same change was observed when it was added to the film. In particular, by applying this film to the process of beef preservation, we judged the freshness of beef by monitoring the changes in the TVB-N value and pH value during the storage process of beef and found that the film showed obvious color changes during the storage process of beef, from blue (indicating freshness) to red (indicating non-freshness), and finally to yellow-green (indicating deterioration), which indicated that the color change of the film and the freshness of the beef maintained a highly consistent. [ABSTRACT FROM AUTHOR]

Smart film is widely used in the field of food packaging. The smart film was prepared by adding anthocyanin-rich Robusta coffee peel (RCP) extract into a chitosan (CS)–glycerol (GL) matrix by a solution-casting method. By changing the content of RCP (0, 10%, 15% and 20%) in the CS–GL film, the related performance indicators of CS–GL–RCP films were studied. The results showed that the CS–GL–RCP films had excellent mechanical properties, and CS–GL–RCP15 film maintained the tensile strength (TS) of 16.69 MPa and an elongation-at-break (EAB) of 18.68% with RCP extract. CS–GL–RCP films had the best UV-vis light barrier property at 200–350 nm and the UV transmittance was close to 0. The microstructure observation results showed that CS–GL–RCP films had a dense and uniform cross section, which proved that the RCP extract had good compatibility with the polymer. In addition, the CS–GL–RCP15 film was pH-sensitive and could exhibit different color changes with different pH solutions. So, the CS–GL–RCP15 film was used to detect the fermentation process of pickles at 20 ± 1 °C for 15 days. The pickles were stored in a round pickle container after the boiling water had cooled. The color of the CS–GL–RCP15 film changed significantly, which was consistent with the change of pickles from fresh to mature. The color of the smart film changed significantly with the maturity of pickles, and the difference of ΔE of film increased to 8.89 (15 Days), which can be seen by the naked eye. Therefore, CS–GL–RCP films prepared in this study provided a new strategy for the development of smart packaging materials. [ABSTRACT FROM AUTHOR]