Development, characterization and food applications of active and intelligent nanocomposite films loaded with bioactive compounds

Objective: This thesis was carried out in order to develop active and intelligent bionanocomposite films enriched with zein nanoparticles in which the functional properties of chestnut, cedar and sweetgum shell wastes are evaluated and to evaluate innovative food packaging in food applications. Material and Methods: In this study, it was carried out in five stages including determination of the most suitable method and conditions for the production of zein nanoparticles in which the shell extracts are encapsulated (I), determination of the most suitable carbohydrate and protein materials to be used in the development of nanocomposite films (II), the characterization and optimization of active nanocomposite films containing zein nanoparticles (III), giving smart properties to the developed optimum active nanocomposite films (IV) and examining the model food applications with film formulations having the best properties by two different methods as packaging and surface coating (V). Zein nanoparticles encapsulated chestnut, cedar and sweetgum shell extracts, which are obtained under optimum conditions based on their bioactive properties, were produced under different mixtures and process conditions by using high-speed homogenization, ultrasonic homogenization and nanoprecipitation methods. Particle size, transmittance, polydispersity index, zeta potential values and encapsulation efficiency of zein nanoparticles were analyzed and optimum nanoparticle production conditions were determined. Active nanocomposite films were produced by incorporating zein nanoparticles obtained in the most suitable methods and conditions into carbohydrate and protein-based film materials. In order to determine the composite film formulation, the properties of the films obtained with carbohydrate-based biopolymers as sodium alginate, pectin, carboxymethyl cellulose, and proteins as gelatin, egg albumin and sodium caseinate were defined and the most suitable carbohydrate and protein type was selected. Based on the mechanical properties, water vapor permeability and opacity values of the active nanocomposite films, the nanocomposite film formulation with the optimum carbohydrate/protein ratio, zein nanoparticle ratio and glycerol concentration was determined. In addition, thermal properties, color values, moisture content, water solubility, antioxidant activity, total phenolic content, antimicrobial properties of bionanocomposite films and volatile compounds and oxygen permeability in optimum film samples were analyzed. Intelligent properties were tested by adding indicators suitable for food contact (anthocyanin and curcumin) into optimum active nanocomposite films. Packaging and coating applications of the developed active and smart nanocomposite films were carried out in fresh foods selected from meat, milk and fruit-vegetable groups. During storage, the pH values, color values, texture properties, total phenolic content and microbiological quality changes of the foods and the compatibility of the indicator with the quality properties were examined. Results: The encapsulation efficiency of zein nanoparticles loaded with chestnut, cedar and sweetgum shell extracts obtained by using nanoprecipitation, high speed homogenization and ultrasonic homogenization methods varied between 34,03%and 96,83%. The lowest particle size was determined as 132,81 nm for zein nanoparticles loaded with sweetgum shell extract obtained by nanoprecipitation method. While nanoprecipitation method was more suitable for the production of chestnut and cedar shell extract loaded nanoparticles, high speed homogenization method was found suitable for the production of sweetgum shell extract loaded nanoparticles. For the active nanocomposite films obtained by adding active nanoparticles to the selected composite films, the carbohydrate:protein ratio in the films was 25:75 under optimum production conditions for all three extracts, based on minimum water vapor permeability, target elongation percentage and maximum opacity, and the ratio of glycerol and zein nanoparticles differentiated. The total phenolic content values of the chestnut, cedar and sweetgum extract-based nanocomposite films were found in the range of 7,56-37,55, 3,56-24,27 and 2,82-24,08 mg gallic acid/100 g dry weight, respectively. Active nanocomposite films developed for all three extracts showed antimicrobial activity against Escherichia coli, Listeria monocytogenes and Staphylococcus aureus microorganisms. It was determined that the glass transition temperature (Tg) of the nanocomposite films decreased as the zein nanoparticle ratio increased. Among the films, active and smart nanocomposite film containing chestnut shell extract loaded zein nanoparticles (5,78%) has the best film properties with low water vapor permeability, low moisture content, low water solubility value, high total phenolic content, high antioxidant capacity value, appropriate opacity and color values. For active and smart nanocomposite packaging and coating applied Kasar cheeses, while control and coating groups could be preserved for 21 days without spoiling (Total aerobic mesophilic bacteria >6 log cfu/g), the packaged samples lost their quality at the same extent at the end of 35 days. In nanocomposite packaging and coating applications made in mandarin fruit, pH, textural properties and total phenolic substance content were preserved in both applications, while the coating application especially contributed to the limitation of microbiological deterioration. In nanocomposite packaging and coating applications carried out with cucumber, no significant differences were observed compared to the control group, and it was determined that the shelf life of cucumbers was 12-14 days. The application of packaging with nanocomposite film in chicken meat provided a slower increase in microbial load of the samples. Conclusion: In this thesis study, it was ensured that chestnut, cedar and sweetgum shell wastes were evaluated by using their functional properties and converted into value-added products in food packaging. Optimal conditions were obtained to maintain the properties of shell extracts which are rich in phenolic compounds and loaded into zein nanoparticles and to provide active properties in nanocomposite films. In addition, active nanocomposite films have been given smart properties by means of natural color indicators. With this simple and low-cost method, a measurable color difference was determined in the films at specific pH values during the storage of foods. It has been concluded that packaging application of Kasar cheeses and chicken meat with active and smart nanocomposite film and coating application in mandarin fruits with active and smart nanocomposite solution are effective applications for preserving the quality of food and slowing down microbial growth. It was observed that the applications were not effective at the desired level in foods with a high respiratory rate such as cucumber. It has been evaluated that the developed active and smart nanocomposite packaging or coating application will be effective as a package in hard cheeses and as a coating in fresh fruits and vegetables with low respiratory rate. Keywords: Shell extracts, Nanoparticles, Bionanocomposite packaging, Active packaging, Intelligent packaging