The team of Academician Shan Yang of Hunan Academy of Agricultural Sciences has made progress in a new method for grafting chitosan-ferulic acid copolymer in the stratum corneum of fruit mimicry

At present, the food packaging industry is highly dependent on non-degradable plastic products, but the overproduction and consumption of plastic packaging leads to serious ecological and environmental problems and endangers human health
.
Therefore, the development of bio-based materials that are degradable and environmentally friendly has become a current trend
.
Chitosan, as a cationic polysaccharide, has potential application prospects in the food industry because of its wide origin, non-toxic, biodegradable, antibacterial properties and good film-forming ability
.
However, the poor water solubility and antioxidant capacity of chitosan greatly limit its application, and chitosan conjugates with excellent performance and corresponding bio-based membranes
can be obtained by grafting copolymerization.
Compared with other grafting methods, the Fenton system-mediated grafting method is widely used because it is simple, effective, environmentally friendly and non-toxic, but the reaction time of this method is too long and the degree of substitution is low
.
Therefore, there is an urgent need to explore a suitable method to improve the efficiency
of Fenton system-mediated grafting.

 

Recently, Associate Researcher Shenghua Ding of Shan Yang's team has made progress in the preparation of chitosan-ferulic acid copolymer and corresponding active film in ultrasound synergistic Fenton system, and the relevant results are based on "Ultrasonication significantly enhances grafting efficiency of chitosan-ferulic acid co.
" njugate and improves its film properties under the Fenton system" was published in Food Research, a top journal in the field of agricultural and forestry sciences International (IF:7.
425), Xu Haishan, a 2020 master's student of our institute, is the first author, Associate Researcher Ding Shenghua is the corresponding author, Longping Branch of the College of Biology of Hunan University is the first, and the Institute of Agricultural Products Processing of Hunan Academy of Agricultural Sciences is the second
.
The research was supported
by the National Natural Science Foundation of China (32272257), the Natural Science Foundation of Hunan Province (2022JJ30330), Changsha Outstanding Innovative Youth Training Program (KQ1905025) and other projects.

 

In this study, chitosan-ferulic acid copolymers were prepared by ultrasound-Fenton system (FUS) at different times, and the corresponding films were obtained by FUS at the appropriate time, and the structure, function, rheology and physical properties were studied
.
Compared with the traditional Fenton system, FUS improves the grafting rate of the copolymer, and with the extension of ultrasound time, the grafting first increases and then decreases
.
The copolymer (FUS1) prepared by FUS with an ultrasonic time of 1 min had the highest grafting rate (121.
28 mg/g), and its grafting time was shortened from 12 h to 1 min
compared with Fenton grafting.
FT-IR and XRD results showed that ferulic acid was covalently linked to chitosan by ester and amide bonds, and the crystallinity of the copolymer was significantly lower
than that of chitosan.
SEM and Mw analysis showed that the degree of degradation of the copolymer increased
with increasing ultrasound time.
In addition, the DPPH and ABTS radical scavenging activities of FUS1 are the closest to Vc and have the best antibacterial effect
.
Therefore, FUS1 is selected to prepare the active film
.
The viscosity of FUS1 film liquid is significantly lower
than that of chitosan film solution.
Compared with chitosan-based membranes, the ultraviolet transmittance of FUS1 membrane is close to 0, the permeability of water vapor, oxygen and carbon dioxide is significantly reduced, and the water solubility and tensile strength are increased by 58.
09% and 25.
72%.

Therefore, the ultrasound-Fenton system is an efficient method for the preparation of food active packaging materials, and FUS1 film has broad application prospects
.

 

In this study, the grafting efficiency of chitosan-ferulic acid copolymer prepared by ultrasound-Fenton system and the traditional Fenton system was compared for the first time, and the effects of different ultrasonic times on the grafting efficiency, structural properties, thermal stability, oxidation resistance and antibacterial properties of the copolymer were explored, and a green, environmentally friendly and efficient method for the preparation of chitosan-ferulic acid copolymer with excellent performance was developed, and an active packaging film
suitable for fruits, vegetables and fresh prepared foods was developed.