Evaluation of Some Chemical Constituents of Some Selected Energy Drinks
CHAPTER ONE
Aim and Objectives
The aim of this work is to carry out comparative study on the physicochemical properties and some chemical constituents of selected energy drinks. This will be achieved through:
- determination of the caffeine and aspartame concentrations of the energy drinks;
- determination of the carbohydrate (sugar)contents;
- determine the physicochemical properties of energy drinks;
- determination of the level of heavy metals (Cu, Zn, Pb, Cd, Mn, Fe) in them;
- determination of micronutrients (K, Ca,) present in them;
- using Statistical Analysis to analyse and compare between the powdered and liquid forms of energy drinks;
- comparing the obtained results with set standards by regulatory
CHAPTER TWO
LITERATURE REVIEW
Review Work on Caffeine
The term ―energy drinks‖ refers to beverages that contain caffeine in combination with other ingredients such as taurine, guarana, and B vitamins, and that claims to provide its consumers with extra energy. There is limited evidence that consumption of energy drinks can significantly improve physical and mental performance (Scholey and Kennedy, 2004), driving ability when tired (Reyner and Horne, 2002), and decrease mental fatigue during long periods of concentration (Kennedy and Scholey, 2004). Unfortunately, the body of literature is limited and it is not known whether these improvements are due to the caffeine, other herbal ingredients, or as a result of the combination of the ingredients found in a beverage (Scholey and Kennedy, 2004).
The caffeine content of a single serving of energy drink (8 to 12 fl oz) can range from 72 to 150 mg; however, many bottles contain 2-3 servings, raising the caffeine content to as high as 294 mg per bottle. In comparison, the caffeine content, per serving (8 fl oz.), of brewed coffee, tea, and cola beverages ranges between 134-240 mg, 48-175 mg, and 22-46 mg respectively (Nawrot et al., 2003). A recent literature review determined that consumption of up to 400 mg caffeine daily by healthy adults is not associated with adverse effects (Nawrot et al., 2003). However, groups that are at risk, such as women of reproductive age and children, should limit their daily consumption of caffeine to a maximum of 300 mg for the former and 2.5 mg/kg body weight for the latter; (Nawrot et al., 2003) thus they may need to avoid consuming energy beverages with a higher caffeine content. A recent survey of 78 youth (11-18 years) found that 42.3 percent of participants consumed energy drinks (O’Dea, 2003). However, the effects of ingredients found in energy drinks on children and an adolescent has raised concern. In adolescents, caffeine consumption has been associated with an increase in blood pressure (Savoca et al., 2004). Based on the limited data regarding safety, it is not recommended that children or adolescents consume energy drinks.
CHAPTER THREE
MATERIALS AND METHODS
Materials
Chemicals and reagents Methanol (HPLC grade) Acetonitrile (HPLCgrade)
Buffer tablets (pH 4.00) – (Reagent grade) (pH Range 3.98 – 4.02) Buffer tablets (pH 7.00) – (Reagent grade) (pH Range 6.95 – 7.04) Caffeine (Reagent grade) – HPLC/STD/012
Aspartame (Reagent grade) – HPLC/STD/009 6 M HCl (50 ml in 100 ml of water)
2.5 M NaOH (100 g in 1000 ml of water) Aqua regia
0.050 M 3, 5-dinitrosalicylic acid Sucrose stock solution solution
Preparation of stock solution
Preparation of standard solution for AAS
A stock solution of each of the element was prepared by dissolving an appropriate amount (1.000 g/ 1000 ml) for Cu, Zn, Pb, Mn, P, and Fe, and (2.542 g/ 1000 ml), (2.497 g/ 1000 ml), (1.907 g/ 1000 ml) for NaCl, KCl, CaCl respectively to get a concentration of 1000 ppm. Five standard solutions covering the range 0-10 µg/ml in 100 ml volumetric flasks were prepared for each of the element. This was used to prepare standard calibration curve for each element.
Preparation of standard solution for HPLC
Caffeine and aspartame stock solutions were prepared by dissolving 10.0 mg of caffeine and 18.0 mg of aspartame standard into a 25 ml volumetric flask each of distilled water to give a concentration of 0.4 g/dm3 and 0.72 g/dm3 of caffeine and aspartame respectively. From each individual stock standard, 4 ml was pipetted into 25 ml volumetric flask and make up to mark with distilled water. Intermediate standard (1 ml, 2 ml, 3 ml, 4 ml, 5 ml) respectively was pipetted into 10 ml volumetric flask and made up to mark with distilled water and named (1st , 2nd , 3rd , 4th , 5th levels respectively). All levels were filtered with whatman filter paper into a beaker or centrifuge bottle. The filtrate were transferred into the auto sampler vials and cork and injected into HPLC in triplicate. The absorbance for the standard solutions were recorded and used to plot a standard calibration curve.
CHAPTER FIVE
DISCUSSION
Physicochemical Parameters of the Samples
pH
Table 4.1 shows the mean ± SD of the pH of the sampled energy drinks. The pH ranged from 4.47 ± 0.012 – 5.96 ± 0.012. Sample HC (liquid) had the least pH while sample PA (powdered) had the highest. The results were higher than pH values of 2.75 – 3.66 reported by Mohammed et al., (2012) for soft and energy drinks in Basrah, Iraq. They were within the pH ranged of 4.2 – 6.3 reported by Adeleke and Abiodun (2010) for local beverages in Nigeria, and had similarities with pH values of 4.2 – 6.3 reported by Obuzor and Ajaezi (2010) for malt beverages. All samples pH are acidic (i.e. their pH values are less than 7). The reason behind the low pH values of these beverages may be attributed to the CO2 gas used in the preservation of these beverages or the presence of other acids such as citric acid, phosphoric acid, ascorbic acid, malic acid, tartaric acid used as preservatives (Bassiouny and Yang, 2005; Ashurst, 2005). These acids inhibit the growth of microorganisms such as bacteria, mould and fungi which may contaminate the beverages. Drinking acidic beverages over a long period can erode tooth enamel and predispose the consumer to dental disease (Marshall et al., 2003; Bassiouny and Yang, 2005). A correct balance pH in the body is crucial to good health. Monitoring pH levels in beverages is important because unbalanced drinks can lead to tooth decay, an exposure to metallic chemicals and a weakening of the immune system. The pH of the analyzed energy drinks is in the range recommended by FDA for caffeinated drinks and coffee of 4.7 and 6.0 (FDA, 2003).
CHAPTER FOUR
RESULTS
Physicochemical Parameters of Samples
The mean concentration ± SD of the physicochemical parameters (pH, turbidity, total dissolved solids (TDS), and conductivity) of the sampled energy drinks (liquid and powdered) are shown in Table 4.1.
CHAPTER SIX
Conclusion
Debate regarding the overall risks and benefits of energy drinks has gained momentum in recent times. Health researchers agree that caffeine consumption can have adverse health consequences, particularly at high doses. Among the most common negative effects are increased anxiety, panic attacks, increased blood pressure, increased gastric acid, bowel irritability, and insomnia.
Recommendations
Energy drinks have been associated with adverse health effects and the claims made by manufacturers about the benefits of energy drinks do not highlight risks associated with excessive consumption of a combination of the ingredients contained in energy drinks. Long term effects of energy drinks consumption of children and young people have not been adequately studied. Therefore, it is recommended that further research be carried out on the adverse effects of energy drinks on children. Research is also needed to be done on the effects of the combination of ingredients on health and excessive consumption of those ingredients to children and adolescents. People need to be educated and given proper awareness on the health risks associated with energy drinks.
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