Ph.D. Dissertation:

Optimization of extraction of cinnamon by pulsed electric process; evaluation of antioxidant and antimicrobial properties and the effect of extract coating on the quality and control of microbial contamination of apple fruit in cold store

This study was carried out in two phases. In the first phase, the effect of electric pulses field on extraction, antioxidant and phenolic properties of cinnamon extract was investigated. Independent variables included voltage (2 to 6 kV) and pulse number (40-60). Experimental design was performed using the central response surface procedure software and central composite design. The extracts were subjected to extraction efficiency, total phenolic compounds, free radical scavenging ability (DPPH) and EC50. After statistical analysis the optimum conditions of extraction of voltage of 5.12 kV was determined as 40 pulses. Under these conditions, extraction efficiency, total phenolic compounds, free radical scavenging ability and EC50 were 5.06%, 505.9 mg / kg, 91.7% and 1.04 mg / l, respectively. Statistically significant difference was observed with the control sample. Extraction and analysis of extract at optimum point confirmed the results. Finally, the optimum treatment was selected based on initial tests (highest extraction efficiency and phenolic, DPPH and EC50 free radicals) and evaluated with antifungal control in the model system with a control treatment (traditional method). In the second phase, the effect of edible coating of chitosan as well as the mixture of chitosan and optimum extract of cinnamon on microbial load and shelf life of apple fruit were investigated. The following tests were performed every month to evaluate apple quality during cold storage: total soluble solids (TSS), titrable acidity (TA), apple skin color (factors L*, a*, b*), apple firmness, Weight loss, pH, CO2 and vitamin C were measured. At the end of storage, a panel test was conducted to evaluate the overall acceptability of the fruit by expert testers at inter-cropping intervals compared to the control treatment. The results were then analyzed using SAS software and the effects of chitosan coating treatment and the combination of chitosan with cinnamon 5% and 10% on enhancing quality, shelf life and reduction of apple fruit storage wastes. The results showed that the effect of chitosan edible treatment as well as the mixture of chitosan and cinnamon extract on most of the traits were significant and the effects of treatments on apple cultivar showed different results.

Keywords: Cinnamon, Apple, Electric Pulse Field, Shelf Life