Production of active composite film containing oxygen scavenger and usage in packaging peanut

In this study, multilayer oxygen scavenging active composite films were produced from edible films containing antioxidant(s) with polypropylene/polyethylene terephthalate composite film. In the study, conductive hydro-drying technique was used for the first time to produce the edible/active films. The produced active films were used in peanut packaging and the effect of the film on the shelf life of peanuts was determined. The study was carried out in two stages. In the first step, the edible film types were select to be used in multilayer active composite film production. For this purpose, composite films were prepared using sodium caseinate, sodium alginate, hydroxypropyl methyl cellulose and gluten/soy proteins (3:1) based films with polypropylene/polyethylene terephthalate (P) film and their oxygen gas permeabilities were measured. Since the oxygen gas permeability values of composite films prepared using sodium caseinate and sodium alginate (PK and PA) were 4.89, 6.62 cm3 mm/m2 day atm, respectively, and these values were lower than the permeability value of the P film (11.26 cm3 mm/m2 day atm), it was decided to use these films in the active films production. Oxygen scavenging multi-layered active composite films were produced by adding sodium ascorbate, α-tocopherol, pomegranate peel and green tea extract, which have antioxidant properties to PA and PK composite films. The oxygen absorbing capacity, antioxidant activity, oxygen gas permeability, water vapor permeability and mechanical properties of the films were determined. Sodium ascorbate showed the best oxygen absorbing capacity among antioxidants used. Sodium caseinate/polypropylene/polyethylene terephthalate film containing 30% sodium ascorbate (PKAs) was found to have the highest oxygen absorbing capacity with 2.26 mL/g and the highest antioxidant activity with 250.51 µmol TEAA/g film. In addition, it was determined that the film with the lowest oxygen gas permeability was the PKAs film, and the oxygen gas permeability of the PKAs film (2.31 cm3.mm/m2.day.atm) was approximately 5 times lower than the P film. As a result of these analyzes, it was decided that the most ideal multilayer active composite film to be used in peanut packaging was PKAs. In addition, sodium alginate/polypropylene/polyethylene terephthalate composite film containing sodium ascorbate (PAAs) with an oxygen gas permeability of 4.73 cm3.mm/m2.day.atm and sodium caseinate/polypropylene/polyethylene terephthalate composite films containing sodium ascorbate, pomegranate peel extract and green tea extract (PK3) with a permeability of 5.32 cm3.mm/m2.day.atm were used in peanut packaging. In the second stage, peanuts were packaged active composite films of PAAs, PKAs, PK3 and P film with initial packaging gas content of 5% oxygen and 95% nitrogen. Peanuts packed with low-density polyethylene/aluminum composite film under nitrogen gas (T) and peanuts stored in polyethylene bags as the control group (C) were also used in the experiments. The peanuts were stored at room conditions for 8 months, the percent oxygen gas content in the package, water activity and color value (L*, a*, b*) in the peanut samples were measured every two months. The oxygen content of peanuts packaged with PAAs, PKAs and PK3 films decreased from 5.35% to 1.5%, 0.83, and 1.23 values in the 2nd month, respectively and at the end of the storage, their oxygen content was 4.63, 3.20 and 4.95%, respectively. However, the amount of oxygen in the P package increased continuously and reached 14.60% at the 8th month. While the water activity values in all peanut samples did not change much until the 6th month, they increased after the 6th month. The a and b color values of the control group and the packaged peanuts with P film decreased towards the end of the storage, but the color values of the other sample groups did not change. For lipid oxidation, acidity, peroxide, p-anisidine and conjugated diene values were determined in peanut oil every two months. In addition, change in quantity of volatile components (pentanal, hexanal and octanal) was monitored in the control group, T and PKAs-packaged samples. Sensory evaluation in peanut samples was performed on the samples at 6th and 8th months. Acidity, peroxide, ρ-anisidine values in the K group samples were 0.821 mg KOH/g oil, 38.20 meq/kg, 5.11 in the fourth month, respectively, and in the P-film packaged samples were 1.019 mg KOH/g oil, 37.96 meq/kg, 4.01 values in the 6th month, respectively. Even at the 8th month, the acidity, peroxide, ρ-anisidine values of the other samples (T, PKAs, PAAs and PK3) were lower than the values of the K group at the 4th month and the P group at the 6th month. These values show that the shelf life of the K group samples is over in the 4th month and the P group samples are in the 6th month, while the other sample groups have a shelf life of more than 8 months. Pentanal, hexanal and octanal amounts of T and PKAs samples at the 8th month were also lower than the amounts of the K group at the 4th month. In addition, sensory evaluation results show that T, PKAs, PAAs and PK3 samples at 8th months were more appreciated than 6 months old K and P samples. In sensory evaluations, peanuts packaged with T, PAAs, PKAs and PK3 films were equally acceptable. It has been found that PKAs is the most successful film in preventing lipid oxidation in peanuts, and PKAs active film can be a good alternative to the commercially widely used low density polyethylene/aluminum composite film in nuts packaging.