1.1 Introduction
Heavy metals are natural elements with atomic number greater than 20, characterized by a relatively high density (at least 5 g cm−3), and are toxic even at low concentrations (Koller et al. 2018). They are characteristically existing components found in changing variation in the environments and are part of human daily activities, they are also found in important structures and in a range of other artificial mixes (Govind et al., 2014). The activities of human have greatly impacted on some heavy metal biochemical cycles and equalization of which a great number of heavy metals have found its use in various items such as cars and batteries (Oyeleke et al., 2016).
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Research hypothesis and questions, Limitations of the Study and Definition of technical terms.
1.2 Background of Study
Nigerian fruit drinks are non-alcoholic drinks produced and consumed within a locality. Usually, they contain sweetening, flavouring and other naturally occurring or locally obtained ingredients. In Nigeria, the common local drinks are “Zobo” (Zb), “Kunnu Zaki” (Kz). Zb is a brick red non-alcoholic drink prepared by boiling the dried calyx of Hibiscus sabdariffa in water. The extract is filtered and more water can be added. The extract can then be sweetened with sugar after adding the flavouring agent.H. sabdariffa (Roselle) is an annual herb native to tropical Africa reaching up to 2 m. The dried calyces contain the flavonoids gossypetine, hibiscetine and sab- daretine. Small amount of delphinidin 3-monoglucoside, cyanidin 3-monoglucoside (chrysanthenin), and delphinidin are also present (Bernd and Franz, 1990). Juice made by cooking a quantity of calyces with water is used as a cold drink in the West Indies, tropical America, Jamaica, Mexico, Egypt and Nigeria as “Zobo” (Kolawole and Maduenyi, 2004). Kz is prepared from cereals (millet or guinea corn). Other ingredients used in its preparation are ginger, black pepper and sweet potatoes or sugar. It can be prepared by soaking the cereal in water for about twelve hours to get soft. The ginger and the black pepper together with the sweet potatoes are ground together, while the soaked cereal is ground separately using a grinding machine. Hot boiling water would be used to make a thick paste with the ground cereals. The ground ginger, pepper and potatoes mixture would be diluted very well with cold water and mixed with the thick paste with vigorous stirring. The mixture would be allowed for about six hours in which the chaffs from the cereals and the ground ingredient would have settled down. The mixture is filtered with fine sieve. The resulting mixture is colloidal in nature, made up of fine starch granules suspended in a sugar solution that settles on standing. The sweet potatoes can serve as a sweetening agent, but granulated sugar can be added to the desired taste. The ginger and black pepper can be used as flavouring agents.
Metals are elements that cannot be decomposed to simpler units by chemical means. They are shinny, ductile, malleable and usually good conductor of heat, and electricity. Metals have high densities, high melting points, high molar heat of fusion and evaporation (Graham and John, 1978). Heavy metals are generated from both anthropogenic and natural sources and are eventually discharged into the environment (Masindi et al., 2018). The main natural discharge of heavy metals is during volcanic eruptions and weathering of metal-bearing rocks (Ali et al. 2019). The discharge of heavy metals through various man-made activities, for example excessive application of chemical fertilizers, wood burning, coal combustion, vehicle exhaust, mining, smelting and incineration (Ali et al. 2019), has caused a wide spread disruption of the normal biogeochemical cycles of metals causing a larger accumulation of heavy metals in the environment, especially the soil (Pugazhendhi et al., 2018). The major heavy metals of concern include lead, cadmium, arsenic, mercury, copper and chromium because of their toxic impact on human health; for instance, environmental exposure to high concentrations of heavy metals has been linked with various cancers and kidney issues (García et al., 2016). Heavy metals have also greatly affected soil microorganisms and plants growth and development (Sharma et al., 2018). The presence of heavy metals in the environment has been a source of concern over the past few decades due to their persistence, potential harm and toxicological hazards (Ali et al., 2019).
Therefore, in Nigeria where the research was carried out, the activities that was conducted is to know the Investigation of Heavy Metals Contamination of Nigerian Fruit Juice.
1.3 Statement of Problems
The concentration of heavy metals may very well be too low to be of significant concern, but it’s definitely a legitimate reason to avoid eating sizable portions of chocolate on a regular basis. Furthermore, because the cacao beans used to make chocolate come from all over the world, the amounts of heavy metals that they contain can vary widely. Although there’s no guarantee, certified organic chocolate is less likely to be produced from cacao beans that have been grown in a contaminated environment or exposed to contaminants during processing (Carter-Pokras et al., 2007).
The major heavy metals of concern include lead, cadmium, arsenic, mercury, copper and chromium because of their toxic impact on human health; for instance, environmental exposure to high concentrations of heavy metals has been linked with various cancers and kidney issues (García et al., 2016). Heavy metals have also greatly affected soil microorganisms and plants growth and development (Sharma et al., 2018). The presence of heavy metals in the environment has been a source of concern over the past few decades due to their persistence, potential harm and toxicological hazards (Ali et al., 2019). Besides the fact that they are non-biodegradable, they may also undergo microbial or chemical transformation (Nwidi et al., 2015). Recently, Hasani et al. (2019) and Nath et al. (2019) reported that heavy metal polluted environments activate co-selection process and cause a decrease in microbial tolerance to antibiotics due to their ability to co-regulate genes responsible for antibiotic resistance.
1.4 Aim and Objectives of Study
The aim of the study is to Investigate the Heavy Metals Contamination of Nigerian Fruit Juice. In achieving this aim, the following specific objectives were laid out as follows:
- To investigate the presence of metallic impurities and to determine the quantity in these Nigerian fruit drinks.
- To identify the Microorganism Isolated from Nigerian Fruit Juice
- To determine the rate of cadmium, nickel, chromium and copper by fungi and bacteria isolated from Nigerian Fruit Juice
1.5 Significance of Study
This study will be of immense benefit to researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study contributes to knowledge and could serve as a guide for other study.
1.6 Scope of Study
The study focuses on the Investigation of Heavy Metals Contamination of Nigerian Fruit Juice.
1.7 Limitations of the Study
During the course of this study, many things militated against its completion, some of which are:
- Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
- Research material: availability of research material is a major setback to the scope of the study.
- Frequent power failure: This made the researcher append more money on fuel to ensure sustainable power.
- Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet, questionnaire and interview).
1.8 Definition of Terms
E.coli: Is an acronym for Escherichia coli which is a bacterium commonly found in the intestines of humans and other animals, some strains of which can cause severe food poisoning.
Staphylococcal: Staphylococcus (staph) is a group of bacteria. There are more than 30 types. A type called Staphylococcus aureus causes most infections. Staph bacteria can cause many different types of infections, including; skin infections which are the most common types of staph infections.
Isolates: isolate simply means cause (a person or place) to be or remain alone or apart from others.
Phytochemical: This is a substance produced mainly by plants, and these substances have biological activity.
