Document Type

Thesis

Date of Award

5-2015

School/College

College of Science, Engineering, and Technology (COSET)

Degree Name

MS in Chemistry

First Advisor

Mahmoud A. Saleh,

Abstract

The presence of Polycyclic Aromatic Hydrocarbons (PAH) in environmental samples such as water, sediments, and particulate air has been extensively studied, but food samples have received less attention. The objective of this research was to identify and determine the concentration of PAHs in light, medium, and dark roasted coffee including instant and decaffeinated brands. PAHs are toxic compounds that are suspected to be carcinogenic or procarcinogenic. Roasting is a crucial step for the manufacture of coffee, as it enables the development of color, aroma, and flavor, which are essential for the characterization of the coffee quality. Toxic compounds may be formed during the roasting process. Roasting time and temperature conditions of the roasting step must be optimized and controlled to achieve maximum aroma and flavor development. Chemical reactions are known to be responsible for the development of aroma and flavor during the roasting step.. The presence of PAHs in coffee samples has been reported and may be attributed to either contamination of the initial green beans or formation of these compounds during the roasting process. 1 2 Total PAHs concentration was related to the degree of roasting with light roasted coffee showing the least and dark roasted coffee showing the highest level Both instant and decaffeinated coffee brands showed lower levels of PAHs. Naphthalene, acenaphthylene, pyrene and chrysene were the most abundant individual isomers. The concentrations ranged from 0 to 561 ng/g for naphthalene, 0 to 512 ng/g for acenaphthylene, 60 to 459 ng/g for pyrene and 56 to 371 ng/g for chrysene. Intensive food and beverage studies can help determine the amount of PAHs present in the food or beverage intake per item. Thus for coffee beverages, the roasting conditions should be controlled to avoid the formation of PAHs due to their suspected carcinogenic and mutagenic properties

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