Preparation and Evaluation of Physical and Mechanical Properties of Nano Coating of Carboxymethyl Cellulose and Guar Gum and Nanoparticles of Zinc Oxide

The use of edible films and coatings derived from natural biopolymers in the food industry has gained great deals of attraction due to environmental reasons.These films and food coatings, by reducing the exchange of moisture and gases between the environment and food, can reduce the oil absorption during frying and improve the quality and durability of the food. In the present research, an edible, biodegradable film containing carboxymethyl cellulose (CMC) and guar gum containing zinc oxide nanoparticles was synthesized through casting method and the effect of the presence of zinc oxide nanoparticles on the coated product was investigated to investigate the physical and mechanical properties of the films. CMC and guar gum were mixed at different ratios, namely 0:100, 30:70, 50:50, 70:30, and 100:0. In the synthesis of the coatings, glycerol was used as a plasticizer. The effect of each of these percentages on mechanical properties, roughness, gas transmissibility, moisture content, the amount of oil absorption andantibacterial characteristics were studied. The mechanical properties test showed that, by adding the nanoparticles, the elongation percentage, increase of modulus value and tensile strength decreased. In atomic force microscopy (AFM) images captured from the film containing zinc oxide nanoparticles, roughness and bumps were observed to increase, and the accumulation of nanoparticles in the biopolymer film has increased. The results of the study of the antimicrobial characteristics of the edible film indicate that the absence of the nanoparticles in the edible coating positively contributes to bacterial growth. Considering the disadvantages of high oil content in fried products and the effect of edible coating on reducing oil absorption, results of applying the edible coating on potato and eggplant showed that there is a direct correlation between oil absorption and moisture loss in potatoes and eggplants. There is a marked decrease in oil absorption during frying.The highest moisture content and the lowest amount of oil absorption were observed in the sample coated with 70% CMC and 30% guar. Furthermore, trying to apply the coating on strawberry, the film containing CMC and guar at 70:30 ratio had the best durability up to day 5. As a result, the coating developed a suitable barrier to passage of gases and moisture.