Project Materials

Evaluation of Some Heavy Metals Concentrations in Chocolate, Candies, and Tomato Puree

ABSTRACT

This study was initiated as follow-up information on some impounded products tomato puree (Samples A and B) chocolates and candies (Samples C, D, E, and F) imported from China, and sold in Nigerian markets. This result as their failure to meet National Agency for food drug administration and control (NAFDAC) regulatory standard. Samples A, B, C, D, E and F were collected in five markets from each six states of the six geographical zones: North-West (Kano), North-East (Bauchi), North-Central (Kogi), South-West (Lagos), South-East (Abia), and South-South (Rivers) of the country.

In order to evaluate the quality of the products, the levels of some heavy metals (Cu, Mn, Fe, Ni, Zn, Ti and Cr) were evaluated in the samples using X-ray fluorescence (XRF). Concentrations of metals in both tomato puree ranged 4.0 – 4.5 mg/g for Cu, 18.0 – 42.5mg/g for Mn, 26.0 – 62.5mg/g for Fe, 4.0 – 56.0mg/g for Ni, 27.0 – 35.2mg/g for Zn, ND – 25.0mg/g for Ti, and ND – 20.0mg/g for Cr while concentrations of metals in both chocolates and candies ranged 3.0 – 4.2 mg/g for Cu, 40.0 – 55.7mg/g for Mn, ND – 102.5mg/g for Fe, ND – 305.0mg/g for Ni, ND – 42.5mg/g for Zn, ND – 23.8mg/g for Ti, and ND – 10.8mg/g for Cr.

The concentrations of all the metals studied were generally higher in samples A and B compared to recommended levels of these metals in vegetable crops. Also, the data showed that these metals are at higher levels in samples C, D, E and F compared to other studies in candies and chocolates in Nigeria.

Correlation analysis among metals revealed positive correlations, which indicates similar sources of these metals. Also, evaluation of dietary intake of these products daily revealed that sample A (except for Cu and Fe), B, C (except for Cu), D and E are above the daily dietary recommended limit for all the metals studied in food. Thus, frequent intake of these contaminated products is likely to induce health effects arising largely from Cu, Mn, Fe, Ni and Zn.

CHAPTER ONE

INTRODUCTION

1.1 BACKGROUND OF THE STUDY

Recently, there is an increasing concern about the quality of imported foods and food related products in several parts of the world (Maxwell and Neumann, 2009) particularly from China. This, as observed by the United States Congress, was due to the large size of shipments, the many different routes of entry, the variety of foods imported, and the large numbers of potential contaminants make effective interdiction of contaminated foods difficult (Congress Research Service (CRS) Report, 2008).

Additionally, the US Congress observed that many products were brought into the United States by travelers especially residents travelling back and forth regularly to China. Among the common products imported were canned tomatoes, chocolates, candies, biscuits, bean paste, bean curd, teas and various nuts and spices (CRS Report, 2008).

According to the United States Congress Research Service Report (2008), in early 2007, evidence emerged that adulterated pet food ingredients from China had caused the deaths of many dogs and cats. However, toxicological and environmental studies have interest in the determinations of toxic elements in food.

“Food safety” implies absence or acceptable and safe levels of contaminants, adulterants, naturally occurring toxins or any other substance that may make food injurious to health on an acute or chronic basis. Food quality can be considered as a complex characteristic of food that determines its value or acceptability to consumers.

Besides safety, quality attributes includes nutritional value, organoleptic properties such as appearance, color, texture, taste and functional properties (World Health Organization (WHO), 1998).