Search

Layer by layer self-assembly techniqueis one of the newest methods to produce multilayer films relying on the placement of the liquid layers on solid substance. The purpose of this studies is to manufacture multilayer kraftbased on protein biopolymers (zein and whey isolate protein) containing of green tea extract phenolic compounds by utilizing layer by layer self- assembly technique and evaluation antibacterial, physical-mechanical properties and release of phenolic compounds from coated kraft at refrigerator temperature inpH of4.5 and 7. The minimum inhibitory concentrationof green tea powder demonstrates thatEscherichia coli (5mg/ml) compared to Listeria monocytogenes (10mg/ml) is more sensitive. The results of physical properties ofkrafts coated paper showed that thickness, grammage and bulk density increased by coating process. Also, the presence of zein in outer layer caused a significant reduction in WVP and increased air resistance. Evaluation of phenolic compounds release from coated krafts demonstrated that release rate in acidic food stimulant was more than the neutral one. Also, release content of kraft paper with zein as outer layers respect to whey isolated protein was higher in the first days and continued in a longer time. Log reduction value of coated kraft with active bilayer zein against Escherichia coli and Listeria monocytogeneswas 0.25 and 0.06 respectively. According to the results of this study, active zein bilayer kraft is recommended as a carrier of phenolic compounds for the packaging of food products. [ABSTRACT FROM AUTHOR]

Complex coacervation isgenerated through electrostatic interactionbetween oppositelycharged biopolymers(proteinsand polysaccharides). Complexation viaelectrostatic interactions can lead to formation of soluble or insoluble complexes. In the current research, the production and characteristics of the complexes formed from whey protein concentrate (WPC) and gum tragacanth (GT)wereevaluated. In order to find the optimum pH for complexation, absorbance of proteinpolysaccharide mixtures weremeasuredat a wide range of pH (2–8),Furthermore, particle size, zeta potential, microstructure and rheological properties of the complexeswere investigated. Based on the results, the best conditionto form complex betweenWPC and GT was found to be at pH=4.5. WithIncreasing the amount of GTup to 0.75%w/w in a constant protein concentration (0.5% w/w),the lowest and highest particle size for WPC-GTcomplex was foundat protein: polysaccharide ratio of 1: 1 (3018 nm) and 10:1 (4070 nm),respectively. Zeta potential changed from +3.11 mV (0% gum tragacanth) to -6.82 mV due to addition of GT(0.75% w/w). Microscopic images showed the presence of separate spherical particles, except at the concentration of0.05% w/w. The appropriate rheological model to predict flow behavior of complexes was depended on protein-polysaccharide ratio and the dominate flow behavior index was found to be shear thinning. Increasing ofTGconcentration lead tolower flow behavior index as well as higherapparent viscosity, consistency coefficientand the yield stress. [ABSTRACT FROM AUTHOR]

Today one of the most important concerns of the world is the significant volume of waste accumulation associated with the synthetic polymers used in food packaging. Therefore, biodegradable edible films are the best alternative for synthetic polymers and plastics. In this study, biodegradable films of corn zein containing two levels of olive leaf extract (10 and 15% w/w) are produced and their physical, mechanical, colorimetric and micro straucture properties were investigated. The results showed that the effect of treatment on physical, mechanical and colorimetric properties was significant (p <0.05). The results showed that by adding 15% extract, the thickness and moisture absorption increased compared to the control sample. Also, by increasing the percentage of olive leaf extract, there was a significant decrease in solubility and vapor permeability in all three relative humidity (33, 50 and 75%) compared to the control sample. In conclusion, it can be concluded from the results of this study that the combination of olive leaf extract with polymeric zein improves some physical and mechanical properties of edible film [ABSTRACT FROM AUTHOR]