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Preparation and Characterization of Antimicrobial Packaging Films from Cricket Chitosan Enriched with Schisandra Chinensis Extract

Super-packaging Made from Crickets and Korean Herbs

Author

  • Vita Jarolimkova

Summary, in English

Chitosan films for food packaging applications were prepared from shrimp and cricket chitosan, enriched with Schisandra chinensis extract. Physicochemical and antibacterial properties of the films were studied and compared with references studying similar chitosan films. Chitosan is a biodegradable polymer, mostly harvested from shells of crustaceans, which has been studied for packaging applications, as it can improve shelf life of food products, especially when enriched with antibacterial and antioxidant compounds. The addition of these substances, such as herbal extracts, influences the physicochemical properties of the film, which are important parameters for characterization of packaging material, as it is necessary to assess its ability to fulfill the necessary packaging requirements. It was shown that insect chitosan film has superior or equivalent physicochemical properties and superior antimicrobial properties to shrimp chitosan. Addition of S. chinensis extract improved antibacterial and water vapor permeability barrier properties, however resistance to water solubility decreased. The originality of the work lies in the use of extract from S. chinensis, which has not been used in films before and which demonstrated antibacterial effect on Gram-positive bacteria, and in harvesting chitosan from crickets (Gryllus bimaculatus) as an alternative chitosan source, as all previous experiments with chitosan films have been done with crustacean chitosan. Moreover, during the extraction of insect chitosan, novel and effective decolorization method was discovered.

Summary, in English

A substance which can be found in shrimp and crab shells as well as insect cuticle (called chitosan) is able to form films similar to thin plastic sheets (think much thicker shrink wrap). However, unlike plastics, these films can reduce bacterial growth and oxidation of the food that is packed in them. To make their effect even stronger, herbal extracts can be added, leading to a creation of 100% natural, renewable, and biodegradable super-packaging prolonging shelf life of food.
These films have been studied for quite a few years already, however they have always been made from chitosan found in the shells of crabs and shrimps. But as production of seafood is insecure and not exactly sustainable, it is important to try looking for other possible sources. It turns out that the same material can be harvested from insects. The main question therefore was: “Is it possible to make the same films from insects, such as crickets?” After half a year or sleepless nights, kilos of dried crickets, hectoliters of coffee and dozens of experiments, the answer was “YES!” Actually, not only were the films in many aspects the same as those made from shrimps. In some instances, they were even better. For example, they did not dissolve in water that easily (which could be useful in packaging of watery food), and they could even prevent one dangerous bacterium (Bacillus cereus) from growing!
It would be a pity to settle for good, when the films could be made even better. Therefore, a Korean herb called omija, with leaves and fruits containing high level of antibacterial and antioxidant substances, was turned into extract. Cricket films containing this extract became even more lethal to some bacteria involved in food poisoning. Also, the ability of water vapor to move across the films was reduced, which can prevent moist food from drying out and dry food from becoming mushy.
While still in the research phase, these films have the potential to become extremely sustainable packaging material in the future. Harvesting of insect chitosan could be connected to large-scale production of insect protein (one of the most sustainable and efficient protein sources in the world!), meaning that all parts of the bugs would be used. The leaves of omija plant are being thrown away during harvest, even though they have the ability to prevent food from spoiling. Therefore, the main ingredients of these films are almost free, completely renewable, totally biodegradable and definitely able to reduce some of the 40% food losses we suffer due to spoilage and loss of quality.

Publishing year

2015

Language

English

Document type

Student publication for Master's degree (two years)

Topic

  • Agriculture and Food Sciences

Supervisor

  • Weon-Sun Shin (Professor)
  • Jenny Schelin (Associate Professor)

ISBN/ISSN/Other

  • ISBN: 978-91-7623-390-0