Assessment of Leaching of Pottery Processed Foods A thesis Submitted to the School of Graduate studies of Addis Ababa University in partial fulfillment of the requirement for the Degree of Master of Science in Food Selected Toxic Metals in Some
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Date
2015-06
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Addis Ababa University
Abstract
Raw materials from uninspected sources used for making of cooking utensils could be a potential
source for high toxic metal in food prepared in these utensils. Therefore, in the present work, the
level of selected metals (Pb, Cd, and Al) in clay pots was determined. The clay pots were
obtained from two sites kechene and legeberi the areas are selected because of the raw materials
used to make them were brought from suspected places for metal contamination. In addition,
leaching of those metals in some foods (bean stew, tomato sauce and coffee) prepared using
these materials were investigated. Furthermore, factors that can influence metal leaching like
frequent usage of the pots were also studied. Clay pots were crushed while the food and coffee
samples were lyophilized and digested in a closed microwave digestion system. The levels of
metals were determined using flame atomic absorption spectrophotometer (FAAS). The results
showed that level of metals in clay pot from legeberi were Pb (26.7±0.0 mg/kg), Cd (5.6±0.1
mg/kg) and Al (38.74±0.7 mg/kg) and clay pot from kechene had Pb content (0.6±0.3 mg/kg),
Cd (0.3±0.0 mg/kg) and Al (8.92±0.3 mg/kg). In addition, the level of metals leaching in food
samples prepared using clay pots from legeberi showed tomato sauce Pb in range (from 9.6±0.0
mg/kg to 13±0.0 mg/kg), Cd (from 0.5±0.0 mg/kg to 1.2±0.0 mg/kg) and Al (from 11.53±0.4
mg/kg to 15.4 ±0.3). The bean stew prepared using clay pots from legeberi had Pb in the range
(from1.2±0.0 mg/kg to 3.3±0.0 mg/kg), Cd (from 0.14 ±0.0 mg/kg to 0.38 ±0.0 mg/kg) and Al
(from10.8±0.2 mg/kg to 13.5 ±0.3 mg/kg), whereas the coffee samples brewed in coffee pot
from legeberi showed Pb in range (from1.6±0.0 mg/kg to 3.9±0.0 mg/kg), Cd (from 0.18 ±0.0
mg/kg to 0.34 ±0.0 mg/kg) and Al (from1.9±0.0 mg/kg to 3.8 ±0.1mg/kg). However, Pb and Cd
were not detected in any of the food prepared using clay pot from kechene. The level of Al in
food samples prepared in clay pot from kechene was tomato sauce in range (from10.5±0.5 mg/kg
to 11.3±0.6 mg/kg), bean stew (from10.1±0.3 mg/kg to 10.4±0.4 mg/kg) and coffee
(from1.1±0.0 mg/kg to 2.1 ±0.0 mg/kg). Results of the present investigation indicates that metal
(Pb, Cd and Al) content of clay pot from legeberi was significantly higher (p<0.05) than clay
pots from kechene. In this manner, food samples prepared using clay pot from legeberi had high
level of metals (Pb, Cd and Al) beyond the permissible limit allowed by WHO, for Pb (0.01
mg/kg), Cd (0.003 mg/kg), and Al (1mg/kg) in food. Similar trend was observed for Al content
of food prepared using clay pot from kechene. Therefore, metals (Pb, Cd, and Al) leaching due to cooking in legeberi clay pot and Al in clay pot from kechene could be a public health concern.
Keywords: leaching; toxic metals;clay pot;;cooking frequenc
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Keywords
leaching; toxic metals;clay pot;;cooking frequenc