Abstract:Response Surface Methodology (RSM) is a collection of statistical and mathematical techniques useful for developing, improving, and optimizing processes. RSM was used to model and optimize the electrospinning parameters for the spinning of blend CS/PVA nanofibers. In this study, chitosan (CS)/polyvinyl alcohol (PVA) blend solutions (CS (M w =1 X 10 6 ) in 2% acetic acid and PVA (M w =12 X 10 3 ) in deionized water) with different blend ratio ranging from 10/90 to 50/50 were electrospun. CS/PVA (25/75) blend ratio was chosen as base and optimum ratio due to its suitable morphological properties and diameter. In a constant ratio of blend SEM analysis shows that the diameter of nanofibers changed by varying the voltage and extrusion rate in the electrospinning process. Voltage (10-25 KV) and polymer solutions extrusion rate of (0.2-1 ml/hr) from the nozzle were chosen as variables to control the fiber diameter at similar spinning distances (10 cm). Fiber diameter was correlated to production variables by using a second order polynomial function. The predicted fiber diameters were in good agreement with the experimental results.
Introduction. Dairy products are an important part of the diet. Kashk is a traditional Iranian dairy product rich in protein. However, kashk has a high water content and is a good medium for the growth of microorganisms. The aim of this study was to investigate the effect of the ethanolic extract of caper fruit (Capparis spinosa L.) on reducing the microbial burden of kashk.
Study objects and methods. The study objects were three kashk samples. The control sample was kashk without caper extract. Two experimental samples included kashk with 0.211 and kashk with 0.350 mg/mL of ethanolic caper extract. All the samples were tested for pH, sensory and antioxidant properties, colorimetric parameters, and microbial population. The experiments were performed on days 0, 7, 14, 21 and 28 of storage.
Results and discussion. The results showed all the samples had pH within the standard values during the entire shelf life (3.96 to 4.53). The samples with 0.350 mg/mL of the caper extract had the lowest EC50 (12.05 μg/mL), i.e. the highest antioxidant activity. The increased concentration of the extract and storage time resulted in a decrease in L* and increase in b*, while did not impact a*. Staphylococcus aureus population increased more rapidly than Clostridium botulinum during the storage time, and the overall sensory acceptability of the kashk samples on days 0 and 7 received the highest score.
Conclusion. The kashk samples containing 0.350 mg/mL of caper extract had an improved antimicrobial, antioxidant and antifungal properties and can be produced and consumed as a new functional product.
Eggs are one of the most nutritious products on a daily basis. The objective of present research is to investigate the impact of coatings on improving storage time and internal quality of eggs. Coating treatments included control (C), coated with chickpea protein isolate (CPI), coated with PI containing Satureja hortensis (CPISH), coated with PI containing Satureja mutica (CPISM). Internal quality was assessed by air cell depth, shell strength, weight loss, haugh unit, yolk and albumen pH, yolk index, microbial evaluation and scanning electron microscope. The weight loss increased during storage and its highest value was 6.12%. Edible coatings (CPI, CPISH, CPISM) preserved internal quality according to the haugh unit, yolk index and pH over 4 weeks (20 °C) compared with C. Haugh unit (5.04), yolk index (0.31), albumen (9.51) and yolk pH (7.04) were detected in C after 7 weeks. CPISH and CPISM protected shell is observed by scanning electron microscope and these coatings affected the internal quality and were appropriate alternatives to extend storage.
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