Written by Yang Qin
Smart packaging can provide people with information on the quality and safety status of food through sensing and communication functions. Meat products are highly perishable, and microbial spoilage in meat products can be observed by monitoring their pH changes.
Curcumin is a naturally non-toxic compound with good anti-inflammatory, anti-cancer, and antiviral properties. It changes from yellow to orange under alkaline conditions and can be used as a natural pH indicator.
Electrospinning technology can be used to prepare food packaging films, and has great advantages. Studies have reported the use of electrospinning technology to prepare pH sensors from polymer nanofibers and acid-added color compounds. However, most of these sensors are used in seafood products, and the research on smart packaging of chicken is still limited.
Chitosan (CS) is a non-toxic, biodegradable biopolymer. Nanofibers were prepared by mixing chitosan with thermally stable, biodegradable polyethylene oxide (PEO), loaded with curcumin, to prepare a biodegradable and non-toxic nanofiber pH sensor film for detecting the freshness of chicken.
Recently, the research group of Gülüm Šumnu at the Middle East Technical University in Turkey has developed a smart packaging film that can monitor the freshness of chicken. The study found that chitosan, polyethylene oxide, and curcumin have good compatibility and interaction, and a biodegradable and non-toxic nanofiber pH sensor film was prepared by electrospinning technology. This pH and total volatile basic nitrogen response film can be used to monitor the shelf life of chicken products. The relevant results are entitled Monitoring freshness of chicken breast by using natural halochromic curcumin loaded chitosan/PEO nanofibers as an intelligent package, published in the International Journal of Biological Macromolecules
The researchers used chitosan and polyethylene oxide as substrates for loading curcumin. The film-forming solution was first characterized by conductivity and viscosity experiments, and then the relationship between the content of volatile compounds and the color change of the smart packaging film was systematically analyzed. In addition, the nanofiber films were characterized by scanning electron microscopy and thermogravimetric analyzer, and the water vapor permeability and response to volatile ammonia of the films were also investigated.
The film-forming solution was characterized. The results showed that with the change of chitosan: polyethylene oxide (w/w) from 1.5:8.5 to 2.5:7.5, the electrical conductivity of the electrospinning solution increased; the viscosity of the mixed solution did not change significantly; the fiber diameter decreased from 338.66 ± 35.57 nm to 283.18 ± 27.83 nm. DSC results showed that chitosan reduced the melting temperature of the system and the polymer had better compatibility. The results of thermogravimetric analysis showed that compared with chitosan and curcumin, the curcumin-loaded chitosan/polyethylene oxide nanofibers had higher thermal stability. The water vapor penetration rate of curcumin-loaded chitosan/polyethylene oxide nanofiber films was in the range of 7.3 ± 0.06 to 14.27 ± 0.05 × 10 ^ -11 g m ^ -1 s ^ -1 Pa ^ -1. Chitosan: polyethylene oxide (w/w) was selected as a 2.5:7.5 ratio to prepare films with minimal fiber size and small water vapor penetration rate, which have a color response to volatile ammonia. It was used to detect the freshness of chicken breasts (4 ° C) during storage. On the 4th day, the color of the film began to change; at the end of the 5th day, the pH of chicken breasts was 6.53 ± 0.08, and the total volatile basic nitrogen concentration was 23.45 ± 3.35mg/100g, indicating that the food was at the critical value of consumer acceptability.
The surface pH value of the curcumin-loaded nanofiber films was closely related to the change of total volatile basic nitrogen concentration and time. During the deterioration of chicken breast, the film underwent a significant color change. Both surface pH analysis and total volatile basic nitrogen results showed that the chicken breast deteriorated after 5 days of storage at 4 ° C. Curcumin-loaded chitosan/polyethylene oxide pH and total volatile basic nitrogen responsive films can be used to monitor the quality change of chicken products.
