Trace Metals

Abstract

Trace metals, as the name suggests, are available in most food items though in small amount but are extremely essential in our diet. Such trace metals includes Iron, Zinc and Magnesium. It is known that food preparation especially cooking would cause the reduction of the level of these metal ions in the food items. The 3 cooking methods that would be investigated are steaming, boiling and microwaving and thereby determining which cooking method would cause the least reduction of the concentration of metal ions. Research Question: To investigate the effect of three different cooking methods, steaming, boiling and microwaving, on the leaching of Fe3+ ions in Spinach (Spinacia oleracea).

The concentration of iron(III) ions in spinach was determined by ashing a fixed mass of spinach leaves, adding Hydrochloric acid to leach out the Fe3+ ions, and subsequently using the UV visible spectrometry to determine the concentration of ions present. The percentage loss of ions was then recorded at regulated time intervals for the different cooking methods. The spinach was cooked for a total of 5 mins and experiments would be carried out every 1 min. Spinach was chosen to be the vegetable of choice as it contains a high level of iron compared to other trace metals.

The results of this experiment showed that increase cooking time reduces the amount of iron(III) ions in vegetables and that the boiling leaches the most ions followed by steaming then boiling. The results can directly impact our lives as cooking is essential in daily lives. It is known that eating vegetables raw is the healthiest as there would be the highest level of minerals and vitamins in it. Therefore, cooking food items for the shortest time possible would allow greater retention of trace metals, making it more beneficial for consumption.

Chapter 1: Introduction

1.1 Rationale behind Research Question

I am interested in the trace metal iron in our diet due to its wide range of benefits when consumed. Iron is an essential mineral few know much about. The importance of iron cannot be over emphasies in our daily lives. It is a part of the blood cells in the body. The main function of iron is the formations of haemoglobin which carries oxygen from the lungs to the muscles and other organs. If the body is low in iron, fatigue, irritability and headaches may occur. If the deficiency becomes significant, this can lead to anaemia. If left untreated, anemia can be serious, with potentially life-threatening complications . Children and pre-menopausal women are the groups most prone to the disease.

Mild iron deficiency can be prevented or corrected by eating iron-rich foods and by cooking in an iron skillet. Because iron is a requirement for most plants and animals, a wide range of foods provide iron. Good sources of dietary iron have haem-iron as this is most easily absorbed and is not inhibited by medication or other dietary components. Three examples are red meat, poultry and insects. However in this essay I would be investigating using non-haeme leafy vegetable such as spinach.

Although there are so many different sources of iron in the food items around but yet there is still about 48% of children under 5years old suffering from anaemia in less developed countries. This aroused my curiosity about the factors that cause the reduction of iron ions in food items when cooking which results in anaemia in the affected places.

I researched that iron ions would be leached due to the time of cooking resulting in lesser concentration iron ion in the food item itself. In this investigation, I chose the 3 cooking method of boiling, steaming and microwaving as they are the more common ways of spinach. The vegetable used in this investigation would be Spinach (Spinacia oleracea) as it has a high level of iron 3mg in 85g of spinach according to the USDA recommended dietart allowance.

Vegetables/fruits Iron content(mg/serving)

Spinach 6.43

parsley 4.00

beet 3.09

brocolli 1.12

pumpkin 3.1

From this table, it could be seen that spinach has a higher level of Iron content compared to the rest of the fruits and vegetables. Besides, Spinach is easily available at local supermarkets at cheap prices so I could use them in bulk for my experiement. With the higher Iron content, it would be easier to quantify it during the course of the experiment. Another reason why I chose spinach as the choice of vegetable for experiment was because it is my favourite vegetable in my diet.

1.2 Hypothesis

Amongst the 3 cooking methods, microwaving would retain the most amount of Iron ions , followed by steaming and lastly boiling.

Microwaving is a cooking method using electromagnetic waves for resonance of water molecules in the food item to cook it. It would retain the highest amount of iron ions as there is no direct contact with water hence leaching of ions would be minimal. Since water is not used as a direct heating medium, it would retain more ions compared