Emel Ünal

Use of Antimicrobial Edible Films and Coatings as Packaging Materials for Food Safety

In recent years, the packaging industry has also started to research new technologies due to increased consumer demand for the minimally processed foods. One of these new technologies is edible films and coatings produced from natural polymers such as protein, polysaccharide, and lipid derived which are biodegradable and could be used as active packaging material. Researches on the use of edible films as packaging materials continue because of the potential of these films to enhance food quality, food safety, and product shelf life. Edible films and coatings have many advantages such as biodegradability, edibility, bio-compatibility with aesthetic appearance and barrier properties against oxygen, ability to resist physical stress. Edible films and coatings are also can be used as a carrier of natural or chemical antimicrobial agents such as organic acids, chitosan, nisin, lactoperoxidase system, and some other plant extracts and essential oils. So they may reduce the risks of growth of spoilage or pathogenic microorganisms in foods by the addition of antimicrobial substances in edible films and coatings and so can prolong the shelf life of foods. Choosing the active antimicrobial is important to prolong shelf life. For effective antimicrobial selection, some possible interactions must be considered such as between the target microorganisms and antimicrobial, film-forming biopolymer, and other food components. In recent years, effective results have been achieved by using antimicrobial edible films and coatings and some model systems have established.

Microbial Metabolites as Biological Control Agents in Food Safety

Ensuring food safety and at the same time meeting such demands for retention of nutrition and quality attributes have resulted in increased interest in alternative preservation techniques for inactivating microorganisms and enzymes in foods. This increasing demand has opened new dimensions for the use of natural preservatives derived from plants, animals, or microflora. Extensive research has investigated the potential application of natural antimicrobial agents in food preservation. Especially the significance and use of microbes as producers of antimicrobial metabolites has increased significantly during the last decades. Reported studies have demonstrated that microbial metabolites from microorganisms exhibited a great numbers of diverse and versatile biological effects about antimicrobial activities. These microorganisms produce many compounds that are active against other microorganisms, which can be harnessed to inhibit the growth of potential spoilage or pathogenic microorganisms. These include fermentation end products (metabolites) such as organic acids, hydrogen peroxide, and diacetyl, biofilm, exopolysaccharides in addition to bacteriocins and other antagonistic compounds such as reuterin. Up to now, antimicrobial metabolites from lactic acid bacteria (such as nisin) have been mostly used in food preservation. In addition to lactic acid bacteria, some yeast, mold, and another bacteria species as well as some pathogenic bacteria can produce antimicrobial metabolites. Antimicrobial metabolites present in foods can extend the shelf life of unprocessed or processed foods by reducing the microbial growth rate or viability. This offers a new knowledge-based approach to the exploitation of bacteria for food production, from metabolic engineering of microorganisms to produce antimicrobials or nutritionals, to the molecular mining of activities as yet unknown but which could benefit food production. In addition, the availability of the genomes of many food pathogenic and spoilage bacteria may open up new possibilities for the design of novel antimicrobials which target essential functions of these problematic bacteria.