Research hotspots and visualization analysis of fruit and vegetable chitosan preservation based on CiteSpace

【Objective】Fruits and vegetables contain various nutrients and are essential for people’s diets. However, post-harvest fruits and vegetables are prone to decay and spoilage, so extending the shelf life of fruits and vegetables has always been a research direction. Chitosan is widely used in fruit and vegetable preservation due to its good biocompatibility, biodegradability, safety, film- forming properties and antibacterial properties, which can extend the storage period of fruits and vegetables. In recent years, research has reported the successful application of chitosan biofilm in fruit and vegetable preservation. CiteSpace has been used to create a scientific knowledge map of chitosan’s application in fruit and vegetable preservation research, and quantitative comparation has been conducted on domestic literature on chitosan’s application in fruit and vegetable preservation research. The aim is to grasp the current research status of chitosan’s application and provide reference value for future research on chitosan’s application in fruit and vegetable preservation.【Methods】This work employed the bibliometric approach to visualize and analyze 930 Chinese and 803 English works of literature from 1991 to 2023. Citespace was used to create graphs, and statistics from various dimensions, including authors, institutions, countries, research hotspots and evolutionary trends, were summarized.【Results】The general pattern of publications from 1991 to 2023 indicated an upward trend in terms of quantity, by the end of2022, there were 47 publications in Chinese and 100 publications in foreign languages. The number of publications increased to more than 30 per year in Chinese and more than 80 per year in foreign languages. Science and Technology of Food Industry, Food Science, and Food Research and Development were the top three journals in the CNKI database for publications, while Food Chemistry (42 articles), Scientia Horticulturae (41 articles), and Postharvest Biology and Technology (39 articles) were the top three journals in the WOS database for publications. The writers’distribution indicated that the main authors interacted and collaborated closely in the groups they had already formed, exchanging messages regularly. However, generally speaking, there was less cross-institutional cooperation—mostly between individuals. Universities and institutes made up the majority of research institutions. Brazil, India and China were the top 3 nations in terms of publications. The freshness preservation impact, shelf life, edible coating film and other factors were both domestic and foreign hotspot areas, according to an analysis of the clustering of research hotspots. The foreign literature on chitosan- related research was more extensive, covering topics like microencapsulation and chitosan quaternary ammonium salt. The primary focus of Chinese research hotspots was the impact of chitosan on the freshness preservation and storage quality of fruits and vegetables. Here is a summary of the research hotspots in this area, which fall into the following categories: composite chitosan film, chitosan preservation mechanism, the combination with emerging technological means, chitosan composite treatment and other fields. Due to its shortcomings—poor moisture barrier, limited air permeability, weak mechanical qualities, etc.—a single chitosan membrane finds it challenging to meet all of the requirements for preserving fresh fruits and vegetables after harvest. The research demonstrates the advantages of several composite antimicrobial membrane types over single chitosan membranes, as well as the notable enhancement of their antibacterial characteristics. In fruit and vegetable preservation, combining chitosan with other treatments is also one of the hotspots for preservation research. Examples of these treatments include the use of chitosan in combination with ethanol and a magnetic field treatment, chitosan and ultrasonic treatment, chitosan and salicylic acid, and chitosan in combination with other treatments, which increase the efficacy, compared to a single treatment. In vitro experiments and complex food matrices have revealed the broadspectrum antibacterial characteristics of chitosan. Its antimicrobial activity is dependent on its molecular weight, degree of deacetylation, concentration, microorganism and environmental variables (pH, temperature). Chitosan’s antioxidant qualities as a preservative have been proven in vitro, and to some extent, these qualities are favorably connected with the level of deacetylation. Food quality decline is mostly caused by enzymatic reactions, and chitosan can have an impact on enzyme activity. It lessens the amount of fruit and vegetable enzymatic browning that occurs during storage. Lastly, chitosan’s barrier quality is critical to the preservation of fruits and vegetables. The chitosan layer not only blocks exogenous microorganisms but also has selective permeability to oxygen and water vapor to a certain extent, which directly affects the shelf life of food. As a result of the increasing use of composite active ingredients and technological integration, the field has grown quickly from 2020 to the present. New developments include the development of layers of self-assembled edible coated films and the polycrystalline phase transition cold burst phenomenon. Research has also focused more on the preservation mechanism and effective targeted inhibition. Researchers concentrate on the impact of chitosan on the freshness and quality of fruits and vegetables. Other new research hotspots include disease resistance mechanisms, fresh fruits and veggies insurance effect, biopolymer nanoparticles, polysaccharide-based composite film and others.【Conclusion】Because of its special qualities, chitosan has gained a lot of attention in the fruit and vegetable preservation business. Chitosan has a lot of potential for preserving fruitsand vegetables, as seen by the good response to its widespread application. The study on chitosan has advanced recently thanks to advancements in science and technology, and current research topics include polysaccharide-based composite membranes, disease resistance mechanisms, preservation mechanisms, layer self- assembled edible coatings and biopolymer nanoparticles. This paper concluded by summarizing the findings of recent studies on chitosan in the field of fruit and vegetable preservation, laying the groundwork and offering support for further research.