PROXIMATE, MINERAL AND HEAVY METAL ANALYSIS ON ONION PEELS

ABSTRACT

This research study is centered around the proximate, mineral and heavy metal analysis on onion peels. Onion is one of the most common vegetable used in preparing most of our everyday dishes and the peels are of no importance to our daily use. The peels of red onions was analyzed for its nutritional, mineral composition, heavy metal concentration and its  calorific value was calculated to ascertain the balance between nutrients and anti-nutrient factors that determines food quality. The results from the proximate analysis showed moisture content 22.4%, ash content 14.92%, carbohydrate content 23.1%, fat content 1.42%, protein content 0.998% and fibre content by difference as 37.2%. The proximate analysis indicated that onion peels was a potential source of food nutrient and could meet the recommended daily intake and acceptable macronutrient range if augmented with other food. Essential minerals showed that K (293.34mg/l) > Fe (15.2 mg/l) > Ca (15.1 mg/l) >Na (10.57 mg/l) Magnesium (1.02 mg/l) > Mn (0.62 mg/l) >Zn (0.45 mg/l) hence good source of macro-minerals but must be consumed with other foods to meet the required daily intake. Heavy metals were also present with Ni (0.09μg/g) > Cr (0.02 μg/g) > Pb, Cu and Cd (0.01 μg/g). The results similarly showed that onion peels has great food value suggesting the incorporation of onion peels as a part of our diet rather than waste will not only promote green chemistry but will also maximize the nutritional value of our pots and provide optimum intake of nutrients.