What are Trace Metals?
“Trace Metals” refers to the metals that can be present in food at less than 50 mg / kg and with some toxic or nutritional value While other inorganic nutrients such as sodium, potassium calcium, phosphorus are present important to man, nutrients such as lead, cadmium, mercury, arsenic are found to be the cause harmful effects even at low doses of 10 - 50 mg / Kg. Although iron, copper, zinc, etc., it is found that it is necessary for a certain amount in the diet, the same nutrients can it causes side effects if eaten at high levels.
Importance of food testing of metals
1. To identify and understand Food Contaminants- food items can be contaminated with several substances and among these, heavy metals such as ferrous, nonferrous, and stainless steel shavings or broken pieces from certain materials can be a cause for concern. That is why, businesses should identify which of these external factors are likely to contaminate food production and ensure quality control of ferrous metal implants to reduce the risk of contamination.
2. The Challenge of Acquiring Metal- Iron detection has been used for a long time now as a tool and a common part of the food safety practice to obtain foreign metal objects from food. However, metal discovery has also had its limitations in recent times. Mineral foods such as fresh salad dressings or salty foods, including meat, cheese, and freshly baked bread are very helpful and can mimic iron signals. Stainless steel can be very difficult to detect because its signal is very similar to wet / high humidity, high-salt, or mineral-rich foods, including poultry, seafood, fresh fruits and vegetables, and ready-to-eat foods, which may also mix some meat with cheese.
Steps to determine content of metal in food items
There are four major steps involved in the analysis of foods for the metal contents:
1. Obtaining a sample representing the sample at the value obtained for testing. - The homogenization process is similar to macerating in a blender while the dry products are usually machine milled and mixed and filtered before being powdered. Contamination during this step can be avoided by using stainless steel machines. Solid foods, such as chocolate, are sampled by hand cutting / cutting. Meat and meat products are finely ground and then ground in a mortar and in this case, very small amounts should not be taken for analysis.
The fat melts before refining. Liquid foods such as cucumbers, etc. should be blended with a high speed blender. The liquid is usually taken as a sample after it has been thoroughly mixed with a slow, steady rotation of the container. After the sample has been properly homogenized and reduced to a useful condition, it should be stored in an airtight container
2. Destruction of organic matter- Common methods of biological destruction can be broadly categorized into Wet Oxidation, Dry Ashing and Microwave Digestion.
3. Separation and concentration- of the element of interest- It is necessary to use reagents and water with low iron content appropriately considering that concentrated mineral acids are usually used in quantities several times larger than the sample. Even if these reagents are used, a complete reagent removal will be required.
4. Determination- Determination of lead, cadmium, copper, iron and zinc in the diet with an atomic absorption spectrophotometer