Effect of γ-rays on carboxymethyl chitosan for use as antioxidant and preservative coating for peach fruit
Ahmed M. Elbarbarya* and Tahia B. Mostafab a Polymer Chemistry department, National Center for Radiation Research and Technology, Nasr City, Cairo, Egypt b College of Women, Ain Shams University, Cairo, Egypt
Abstract
Carboxymethyl chitosan (CMCS) was synthesized by alkylation of chitosan using monochloroacetic acid and characterized by FTIR and 1H-NMR spectroscopy. Different molecular weights (Mw) of CMCS were prepared by radiation degradation of CMCS in the solution form at different irradiation doses. The structural changes and Mw of degraded CMCS were confirmed by UV-Vis, FTIR and GPC. The antioxidant activity of CMCS were evaluated
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Briefly, 1.5 ml of DPPH solution (0.1 mM, in 95 % ethanol) was incubated with different concentrations of unirradiated and irradiated CMCS solutions. The reaction mixture was shaken well and incubated for 15 min at room temperature and the absorbance of the resulting solution was read at 517 nm against a blank (control). Ascorbic acid was used for comparison as antioxidant materials. The radical scavenging effect was measured as a decrease in the absorbance of DPPH and can be calculated using the following …show more content…
unirradiated CMCS and irradiated CMCS were screened in vitro for their antibactericidal activity (against Gram positive bacteria S. aureus and Gram negative bacteria E. coli) and antifungal activity (against Aspergillas flavus and Candida albicans). In this method, a standard 5 mm diameter sterilized filter paper disc impregnated with samples (1 mg/ml of DMF) was placed on an agar plate seeded with the test organism. The agar plates were then incubated for 24 h at 37 °C for bacteria and 28 °C for fungi. After incubation, the interrupted growth zone (zone of inhibition) around the test material was measured (mm/mg) and used as quantitative indicator of antibacterial and antifungal effectiveness of CMCS. The values obtained were the average of 5 measurements on the same plate at different zones.
2.8. Data analysis
All statistical analysis was performed with SPSS (SPSS Inc., Chicago, IL, USA). Differences at ρ Society, 70, 383-386.
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After lawn inoculating a Meuller Hinton plate and placing the samples of medication, the plate was then incubated for one week at 37 degrees Celsius. The first medication choice was Trimethoprim, this produced a zone of inhibition of 16mm, therefore being sensitive to the bacteria. Antibiotic number two was nalidixic acid, this too, has a zone of inhibition of 16mm but is considered intermediate. The next antibiotic was erythromycin which produced a zone of inhibition of zero and was therefore resistant. The last antibiotic that was chosen to be used in the experiment was ciprofloxacin.
In this lab, the oxidation of a secondary alcohol was performed and analyzed. An environmentally friendly reagent, sodium hypochlorite, was used to oxidize the alcohol, and an IR spectrum was obtained in order to identify the starting compound and final product. The starting compound could have been one of four alcohols, cyclopentanol, cyclohexanol, 3-heptanol, or 2-heptanol. Since these were the only four initial compounds, the ketone obtained at the end of the experiment could only be one of four products, cyclopentanone, cyclohexanone, 3-heptanone, or 2-heptanone. In order to retrieve one of these ketones, first 1.75g of unknown D was obtained.
Paired Differences t df Sig. (2-tailed) Mean Std. Deviation Std. Error Mean 95% Confidence Interval of the Difference Lower Upper Pair 1 CES-D Score - CESD Score, Wave 1 .71718
doi:10.1177/1090198115598983 b. Provide a web address where the article can be accessed electronically by your professor. If not available, then please provide a PDF copy (by uploading via Moodle) or a printed copy (handed in during class) of the article. (1 point) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4752929/pdf/nihms733111.pdf 2. Abstract:
Data for this article was gathered from published journal articles from 2009
The goal of this exploratory study is to determine which variables have the strongest relationships
69, No. 7, pp. 653-660. doi: 10.2105/AJPH.69.7.653. Retrieved from: http://ajph.aphapublications.org/
Purpose The purpose of this experiment was to evaluate the stoichiometric relationship between the testing agents and to identify the products formed. The relationship was found by completing three acid and base neutralization reactions using phosphoric acid, which is a triprotic acid, with different volumes of sodium hydroxide. Introduction Procedure Phosphoric acid solution with a volume of 1.00 mL and a molarity of 6.00 M was transferred into a 125-mL Erlenmeyer flask using a volumetric pipette.
In addition to this, this number of studies is further reduced because many of the studies were not available in full. It is noticed that of 20 studies only abstract were available due to which they were not used for providing literature in this study. Therefore, only 10 studies were considered as relevant and were selected in order to conduct this study effectively. Moreover, these studies were searched by making use of some appropriate keywords, which are highlighted in the next
To better understand the data found, I have organized the literature review into
The data were processed and analyzed using SPSS version 18. Frequencies, cross tabulation, Pearson’s, chi-square test, ANOVA were used to analyze the data. A p-value of <0.05 was considered statistically
CHAPTER 2 REVIEW OF RELATED LITERATURE AND STUDIES This chapter discusses some relevant literature and studies that provide an overview with sufficient knowledge and insight about the present study. This includes articles, journals, published and unpublished studies, and books, which contributes to the study. Related Literature In this section, the researchers provided discussions about the relevant facts, issues and principles in support to the present study.
Aseptic technique was initiated at the beginning of this experiment by cleaning the work surface with disinfected wipes. Personal protectives equipment was also worn. The material utilized in this experiment was: S. epidermidis culture broth, sterile cotton swab, streak plate, forceps in 70% alcohol, a lit tea light, and the three antibiotic disks (novobiocin, gentamicin, penicillin). The first step, I divided a plate into three quadrants and labelled them with the different antibiotic names. Using the lit tea light, like a bursen burner, I flamed the mouth of the S. epidermidis culture.
Results demonstrated that all substances showed bactericidal effect on all studied microorganisms at all concentrations and after a short contact period.90 Sen B H et al (1999) assessed the antifungal properties of 1% NaOCl, 5% NaOCl, and 0.12% chlorhexidine against Candida albicans using cylindrical dentine tubes and found C. albicans to be more resistant in the presence of smear layer than in the absence of smear layer. When smear layer was absent, NaOCl started to display antifungal activity after 30 minutes
CONCEPT OF SHELF-LIFE EXTENSION: Chitosan is a polymer which is extracted from chitin. It is natural, and thusly biodegradable and biocompatible. As a novel food preservative, chitosan offers the possibility to form edible film coatings on fresh or processed perishable foods in order to extend their shelf life. The chitosan film has antimicrobiological properties which allow it to protect the food it is coating.