Professor Xiaofeng Ren, School of Food and Biological Engineering, Jiangsu University published a research paper recently entitled "Insights into ultrasonic treatment on the properties of pullulan/oat protein/nisin composite film：mechanical, structural and physicochemical properties" in the journal “Food Chemistry (Q1, IF: 9.231).” A graduate student of the year 2020, “Lixin Kang,” , is the first author of the paper; Professor Xiaofeng Ren and Dr. Qiufang Liang are the co-corresponding authors of the paper.

Packaging plays a crucial role in protecting food since it improves shelf-life and drastically reduces food waste. Most food packaging materials are manufactured from petroleum resources, which are nondegradable films which can cause severe “white pollution” and may pose a serious risk to food safety by releasing toxic chemicals. Therefore, developing environmentally friendly and sustainable food packaging film is significant in the food packaging industry. Recently, packaging films based on low-cost, abundant, and renewable resources of natural biopolymers, such as proteins, polysaccharides, lipids, etc., have gained more attention.

Oat protein has good film-forming properties and biodegradability. The films developed from oat protein alone have weaker barrier and mechanical properties than other proteins films, limiting their application in food packaging. In this study, pullulan polysaccharide was added to oat protein to prepare a protein-polysaccharide composite film to improve protein film's mechanical and barrier properties. At the same time, Nisin, a natural antibacterial agent, was added to enhance antibacterial activity of (Nis@Op/Pul film) composite film . Ultrasound was introduced to improve its mechanical, structural, and physicochemical properties. The ultrasound treatment significantly increased the elongation at break and transparency of Nis@Op/Pul film by 18.37% and 8.03% and decreased its total soluble matter and oxygen permeability by 8.33% 2.78%, respectively, compared to the conventional method. The structure analysis shows ultrasound enhances intermolecular hydrogen bonding, reduces the crystallinity, and forms a more stable, uniform surface. Moreover, the Nis@Op/Pul film prepared by ultrasound treatment could effectively delay the decay and deterioration of fresh strawberries and prolong their shelf life.

The above research had been granted a Chinese national invention patent (ZL202110457753.5) and applied for an international PCT patent (PCT/CN2022/071248). This work was supported by the National Natural Science Foundation of China (32072355), Sponsored by Qing Lan Project (2020), and the Primary Research & Development Plan of Zhenjiang (NY2021006).

Figure 1. The technology roadmap

Figure 2. Effect of protein-polysaccharide composite films on strawberry preservation

Professor Xiaofeng Ren has long been engaged in the research on applying protein-polysaccharide-based biomaterials in embedding bioactive components and food preservation packaging, and the mechanism and application of ultrasound in the preparation of nanoemulsions. He has presided over 3 projects of the National Natural Science Foundation of China, 2 projects of Jiangsu Province's key R&D plan for modern agriculture, 1 project of Jiangsu Province Agricultural Science and Technology Independent Innovation Fund, and 2 special funding projects of China Postdoctoral Science Foundation and general projects, 1 key R&D project of Zhenjiang City, 3 technology development projects entrusted by enterprises, and participated in more than 10 scientific research projects at the national, provincial and ministerial levels. As the first/corresponding author he had published more than 30 SCI/EI papers in the Journal of Food Chemistry, Ultrasonics Sonochemistry, Journal of Food Engineering, LWT-Food Science and Technology, International Journal of Biological Macromolecules, and 6 books or textbooks. He has authorized 20 Chinese national invention patents (including 6 PCT international patents). Successively won the first prize in the Shennong Chinese Agricultural Science and Technology Award of the Ministry of Agriculture, the first prize in the China National Light Industry Federation Science and Technology Progress Award, the second prize in the Jiangsu Provincial Science and Technology Progress Award, the second prize of the Ministry of Education's scientific research outstanding achievements in colleges and universities, the first prize of the Technology Progress Award of the China Food Science and Technology Society and the Excellence Award of the China Patent Award, etc.