Abstract

Consumer demand for ready-to-eat ‘fresh’ and safe food products with less synthetic preservatives together with well documented food-borne microbial outbreaks drive both research and food industry toward new innovative methods for microbial growth inhibition while keeping food freshness, quality, and safety. Incorporation of natural bioactive agents in the packaging material to increase the shelf life of meat products is a promising technology. Grapes are of special interest because of their high content of phenolic compounds that showed antimicrobial and antioxidant effects. The aim of the present work was to investigate grape seed (GSE) and skin (GSKE) extracts’ antibacterial activity and developing bioactive LDPE/PET films that could be used as food packaging for poultry and meat products. Commercial corona treated LDPE and PET were coated with either grape seed or grape skin extract. Agar plate diffusion method was used for the investigation of the microbial properties of both extracts’ coated films against E.coli as a Gram-negative bacterium and Staphylococcus aureus as a Gram-negative one. LDPE and PET films coated with GSE showed inhibition zones of E.coli growth in the range of 16-25mm, while Staph.aureus growth inhibition zones were in the range of 15-20mm. For LDPE corona films coated with grape seed extract, the minimum inhibitory concentration (MIC) was 0.002g/1cm2 for E.coli and 0.003g/1cm2 for Staph.aureus. While for corona treated PET films/GSE, the MIC for both E.coli and Staph.aureus was 0.002g/1cm2. Corona treated LDPE and PET coated with GSKE showed inhibition zone range of 13-16.3mm with E.coli and 12-20mm with Staph.aureus. For LDPE corona films/GSKE, the minimum inhibitory concentration (MIC) was 0.0009g/1cm2for E.coli and 0.003g/1cm2for Staph.aureus. While for corona treated PET films/GSKE, the MIC was 0.002g/1cm2 for E.coli and 0.003g/1cm2 for Staph. aureus. The Total Phenolic Content of both GSE and GSKE was determined using the Folin- Ciocalteu methodology to be 315.32g (GAE)/kg, and 265.326g (GAE)/kg for GSE and GSKE respectively. The coated films; LDPE/GSE or GSKE, were used to wrap fresh chicken fillets, TVC, Pesudmonads, Brochothrix thermosphacta, Lactic acid bacteria and Enterobacteriaceae counts were determined during the storage period; 10 days for test samples and 8 days for controls. Microbiological analysis for tested samples was done on day 0, 2,4, 6, 8, and10, while for control till day 8. There was a reduction in the populations of the examined bacteria in the range of 0.2-1.4 log cfu/g in case of GSE, while with GSKE the reduction of bacterial populations range was 0.3-1.95 log cfu/g.

Department

Chemistry Department

Degree Name

MS in Chemistry

Graduation Date

2-1-2018

Submission Date

September 2017

First Advisor

Dr. Shoeib, Tamer

Committee Member 1

Dr. Shoeib(Advisor), Tamer

Committee Member 2

Dr.Kontominas (Advisor), Michael

Extent

142 p.

Document Type

Master's Thesis

Rights

The author retains all rights with regard to copyright. The author certifies that written permission from the owner(s) of third-party copyrighted matter included in the thesis, dissertation, paper, or record of study has been obtained. The author further certifies that IRB approval has been obtained for this thesis, or that IRB approval is not necessary for this thesis. Insofar as this thesis, dissertation, paper, or record of study is an educational record as defined in the Family Educational Rights and Privacy Act (FERPA) (20 USC 1232g), the author has granted consent to disclosure of it to anyone who requests a copy.

Institutional Review Board (IRB) Approval

Not necessary for this item

Comments

Acknowledgments I would like to thank God the Almighty for giving me life and the opportunity to gain knowledge during the pursuit of my Master degree at AUC. I wish to express my sincere gratitude to Dr. Michael Kontominas for his guidance and support throughout the duration of my project. I also thank Dr. Kontominas and his kind wife “Vaso” for treating me as family during my stay in Greece. I would also like to thank all the Food Chemistry research team at the University of Ioannina for supporting and helping me with the guidance and knowledge I needed. Dr. Tamer Shoeib words are not enough to express my gratitude to you, without your wise help and support I would not have completed my thesis. I am grateful for Dr. Adham Ramadan for his agreement to top up my research grant and to AUC for the financial support supplied by the Chemistry Department. I’m also grateful for Dr. Noha Youssef for her kind help with the statistical treatment of experimental data.

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