THE UNSEEN TRAP IN THE DEVELOPMENT OF BIOPOLYMERIC MATERIALS WITH NATURAL ADDITIONS: THE IMPORTANCE OF USING HIGH QUALITY ESSENTIAL OILS
Authors: Puscaselu Roxana Gheorghita , Gutt Gheorghe 
Published: February 2023

The benefits of using biopolymers in the food industry have motivated the scientists to develop products with better characteristics than the regular ones. Biocompatibility with the human body, edibility and ease of use have paved the way for biopolymers such as agar, sodium alginate, carrageenan, chitosan, etc. for using it in the biomedical and pharmaceutical industries. In addition to their well-known characteristics, biopolymers have the ability to incorporate various natural substances, representing an almost perfect matrix for them. Studies have shown the effectiveness of incorporating natural compounds with antioxidant, antimicrobial and controlled release. Thus, natural powders or essential oils have been developed. The purpose of this study was to highlight the importance of using good quality essential oils, allowed for consumption, extracted by natural methods, with real benefits for the health. The films were obtained from a mixture of agar, sodium alginate, glycerol and water, after a composition developed in the laboratory and optimized using specific software. Then, 10, respectively 20% essential oils such as lemon, cloves, orange, cinnamon, ginger and grapefruit were added in the cooled film-forming solution. The essential oils were purchased from specialized companies, with quality certificates and considered optimal for consumption, according to the manufacturer. After development, the films with essential oil added presented improved sensory attributes: homogeneity, uniformity, regular edges, better appearance, pleasant color, specific smell and taste, which did not lose its intensity after storage, high gloss and flexibility. The solubility in water has been improved with the addition of essential oil, which is normal if we take into account their hydrophobic nature. However, the microbiological analysis revealed that the essential oils were contaminated. Thus, tested for the incidence of microorganisms, such as coliforms, Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, Enterococcus, yeasts and molds, the films with the addition of essential oil presented bacterial contamination (no yeasts or molds developed on the samples). Unlike the control film, without essential oil into composition, those with a content of 20% clove and grapefruit essential oil facilitated the development of over 100 cfu/g film, and those with lemon and cloves revealed contamination with Escherichia coli with 28, respectively 43 cfu/g film. Listeria monocytogenes was developed only on the sample with orange essential oil, but the microbial load was significant one (22 cfu/g). Enterococcus and coliforms did not develop on the samples tested. Unlike the other films, the control sample, without the addition of essential oil, did not show the microbial contamination. The results obtained are of interest and indicate the importance of early testing of oils embedded in such materials. Although the sensory characteristics and physical or optical properties of essential oil films are far superior to the control sample, the safety of ingestion prevails, especially when these materials are used as a coating for food supplements or, more importantly, as wound dressings.