Research on manufacturing food preservation film using green technology

Biopolymer packaging materialsPackaging materials play an essential role in food preservation and distribution. Currently, synthetic polymers are widely used due to their high mechanical properties, low gas permeability and reasonable price, but they cause many problems in environmental treatment. In recent years, natural materials that are biodegradable and environmentally friendly have attracted much attention in food preservation research. Materials such as cellulose, starch, chitosan, and alginate are becoming more and more popular and gradually replacing artificial polymers. Among them, cellulose stands out with its high durability and diverse applications.

Preservative films are mainly made from chitosan or alginate, while research on cellulose films is still limited. Research has not yet combined the advantages of natural polymers with antibacterial polyphenols, resulting in product preservation times that do not meet transportation needs, especially for export purposes. Furthermore, the current production process is complicated and costly, making market access difficult.

Manufacturing of preservative film from longan seeds

Longan, a popular fruit in Vietnam and many other countries, is often only used for its flesh, while the skin and seeds (accounting for about 30% of the weight) are often discarded. Recent studies have shown that longan seeds contain many valuable biologically active substances such as some polyphenols (gallic acid, ellagic acid, corilagin...). Therefore, the research and manufacture of longan fruit preservation films from cellulose acetate combined with polyphenols extracted from longan seeds is a research direction that is meaningful both scientifically and practically.

In Vietnam, a group of scientists from the Institute for Tropical Technology led by Dr. Le Thi My Hanh conducted a study on the production of biodegradable membranes and quick-dissolving films for application in tea packaging and fruit preservation (code: QTBY01.05/22-23). During the research, the scientists collaborated with Prof. Dr. Savitskaya Tachiana Aleksandrovna and the research group at the Faculty of Chemistry, Belarusian State University in the technology of manufacturing polymer membranes based on natural polysaccharides and determining the characteristics, properties, and structural morphology of the membranes using modern physicochemical analysis methods. The results were positive and the two research groups had a joint international publication in the journal Waste and Biomass Valorization under the SCIE category.

Dr. Le Thi My Hanh and her research team working at the Faculty of Chemistry, Belarusian State University (June 2023)

Results and applications

Scientists have extracted polyphenols from longan seed powder and successfully fabricated a cellulose acetate/longan extract (CA/DC) membrane. The resulting longan extract has the highest total polyphenol content of 179 mg GAE•g-1, demonstrating good DPPH (2,2-diphenyl-1-picrylhydrazy) free radical scavenging ability with IC50 = 65.3 μg.mL-1 and antibacterial activity against E.coli and S.aureus.

Dr. Le Thi My Hanh said: The CA/DC material film at the ratio of CA/DC-10/1.5 (v/v) (CAD1.5) gave the best physical and thermal properties and demonstrated antibacterial activity against E.coli and DPPH free radicals. The test of preserving longan fruit with CAD1.5 film showed good results in preserving longan for 8 days at ambient temperature.

Summary process of CA/DC material membrane sample fabrication

CA is a material with potential for use as a food preservation film to replace synthetic plastic materials. Especially when adding polyphenols or some inorganic nano such as nano Ag... to enhance the antibacterial and antioxidant properties of the material. Longan seeds, an agricultural by-product, are reused as raw materials for polyphenol extraction, contributing to increasing the value and application of this material. With low cost, non-toxicity and high regeneration capacity, cellulose promises to become the main material in the food packaging and preservation industry using environmentally friendly green technology.

Translated by Quoc Khanh
Link to Vietnamese version