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The use of genetically engineered probiotics to express specific enzymes has been the subject of considerable attention in poultry industry because of increased nutrient availability and reduced cost of enzyme supplementation. Phytase enzyme is commonly added to poultry feed to improve digestibility and availability of phosphorus from plant sources. To construct a probiotic with potential of phytate degradation, phytase gene (appA) from E. coli was cloned and transformed into two probiotic bacteria Lactobacillus salivarius and Lactococcus lactis. The results showed plasmid instability, unable to express the gene. The expression of appA gene in L. lactis was analyzed by detecting specific RNA and zymography assay. Phytase enzyme was isolated from cellular extracts of recombinant L. lactis, showing a 46 kDa band upon the SDS-PAGE analysis. Zymogram also confirmed the phytase activity of the 46 kDa band corresponding to the enzyme. An enzyme activity of 4.9 U mL^-1 was obtained in cell extracts of L. lactis. The growth of native and recombinant L. lactis was similar in the presence of two concentrations of ox bile.

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Application of edible coatings to enhance storage life of fresh fruit has recently been under considerable attention. This experiment was conducted in order to explore the effect of chitosan coating and storage temperature on the postharvest life of pomegranate (Punica granatum L.) fruit. Therefore, pomegranate fruits ‘Rabbab-e-Neyriz’ were dipped in 0, 1 and 2% aqueous chitosan solutions, air dried and then stored at 2 and 5˚C with 90% relative humidity for up to 135 days. The application of chitosan coating retarded the respiration rate and weight loss of the fruit regardless of temperature during storage period; however, the retention was higher at 2 than 5˚C. After 135 days of storage, the highest (18.19%) and lowest (9.33%) weight losses were recorded in the control fruit stored at 5˚C and 2% chitosan-treated fruit stored at 2˚C, respectively. The results revealed that postharvest weight losses in pomegranate fruit mainly related to weight losses in the fruit peel and 4-8% reduction in peel weight percentage (of whole fruit) was recorded in the treated fruit. A slight decline in Soluble Solids Content (SSC) and Titratable Acidity (TA) was found during storage in all treatments, while pH and maturity index increased slowly. Scanning electron microscopy of the treated fruit demonstrated that chitosan covered whole pericarp surface and pores of the coated fruit, and revealed more shrivelling symptoms on the peel of the non-coated fruit during storage.

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Broccoli (Brassica oleracea L. var. italica) as an important vegetable has a high postharvest respiration rate, so, it loses its quality rapidly. The use of edible films and coatings as protective layers to create a covering on the surface of fruits and vegetables plays a key role in maintaining the quality of this product. The present research investigated the qualitative and biochemical traits of broccoli coated with tragacanth gum (0, 0.1, 0.2, and 0.4%) and cellophane and uncoated ones (as control) weekly during three-weeks cold storage. Based on the results, coating influenced all measured traits (except flavonoid content, vitamin C and antioxidant activity) and storage time influenced all recorded traits significantly (P< 0.01). The results revealed that over the storage period, the physicochemical and biochemical parameters and visual quality of the broccoli decreased. Tragacanth gum 0.2% led to less weight loss, however, appropriate soluble solids content, and higher titratable acidity and organoleptic properties were recorded for 0.4% coated florets. Cellophane was effective in retaining some physicochemical characteristics, weight, and marketability, but it reduced phenolics. Tragacanth gum coating can be used as a biomaterial, as a substitute for synthetic cellophane film to preserve broccoli.