The purpose of performing this experiment is to determine the glucose concentrations and absorbance of Coke and Gatorade by using a spectrophotometer, whilst being compared to glucose concentrations published by manufacturers. There are trends that show increasing consumption levels of glucose within the past several decades, contributing towards obesity and a decline in metabolic health. This experiment revealed that Coke had an observed glucose concentration of 4.125g/100mL whilst Gatorade had a glucose concentration of 1.18g/100mL. These results are evident that the sucrose within these drinks has been hydrolysed into glucose and fructose, as both drinks have higher glucose levels than claimed by the nutrition labels.
IntroductionConducting this experiment to analyse the concentration of glucose within Coke has helped gain an insight into the increasing levels glucose in commercial drinks. Glucose plays a vital role as it provides aerobic respiration and a source of energy within the body. Increased glucose consumption correlates towards the rise of metabolic health complications such as obesity and diabetes mellitus.
Furthermore, sucrose is known to be a disaccharide, consisting of a fructose and a glucose monomer, therefore when an enzyme invertase or acidic conditions are present, this sucrose can hydrolyse into its monomers. When glucose combines with glucose assay reagent, glucose will undertake a multi-step enzymatic reaction in which D-glucose converts into a 6-phosphogluonate and NADP+ and reduce to NADPH (McCleary, B.V. et.al, 2009). Enzymes are a catalyst known to speed up the rate of chemical reactions by lowering the activation energy of a reaction through binding on a substrate.
In order to catalyse reactions, enzymes require NDP+ and NADPH (specific co-enzymes) to develop the function of glucose-6-phosphate dehydrogenase (McCleary, B.V. et.al, 2009). This experiment utilised a liquid chromatography to analyse the sugar levels in each drink, comparing them to their nutritional information claimed by the manufacturers.
Furthermore this experiment mirrored a 2011 study conducted by Emily E. Ventura, Jaimie N. Davis, and Michael I. Goran, in the aspect that levels of sucrose, fructose and glucose were being measured by a liquid chromatography within a variety of frequently purchased drinks. The difference between the 2011 experiment and the experiment conducted was that it had examined 20 of the most purchased drinks by children and young adults within a larger population (Ventura, et al., 2011). Throughout conducting this experiment, it is evident that the nutritional labels have contradicted their claim. Due to the results from the chromatography, it is hypothesised that Coke will obtain a greater glucose concentration than Gatorade. Materials and MethodsIn order to prepare the glucose, 20 millimoles (mM) of glucose were used to prepare 1 millilitre (mL) of glucose standards in the microcentrifuge tubes of 1,2,3,4 and 6 mM dilutions. Cuvettes were then labelled as 1,2,3,4 and 6G and prepared by adding 35 microlitres (јL) of glucose standard along with 665 µl of distilled water.
Additionally, the same steps were taken when preparing for the Coke, Gatorade and Sucrose standards. Each cuvette had 300 µL glucose array reagents and was mixed well by pipetting. Its absorbance levels were recorded immediately as A1 values before the next cuvette would replace and repeat the previous steps within 2 minute intervals. At 18 minutes, the absorbance of each cuvette at 340nm was recorded at 2 minute intervals and was recorded as an A2 value (Pearson, 2018). 3.0 Results and CalculationsFigure 1: Experimental DataSample A1 (0 min) A2 (+18 min) Absorbance Difference (A2-A1)0mM (Blank) 0.023 0.022 -0.0011mM 0.029 0.203 0.1742mM 0.032 0.587 0.5553mM 0.035 0.717 0.6824mM 0.038 0.835 0.7976mM 0.043 1.144 1.101Coke 0.028 0.483 0.455Gatorade 0.027 0.156 0.129Sucrose 0.025 0.026 0.007As seen from the data the, it is evident that absorbance levels increase along with the glucose sample concentrations. The data also illustrates that Coke has a higher absorbance level than Gatorade. The sucrose sample was also treated at 70°C with a pH 2.5. Figure 2: Sucrose Absorbance levels (A2-A1)Figure 2 represents the absorbance levels within the sucrose levels at different pH levels. As seen from the results, it is evident that the sucrose treated at a higher temperature correlates towards greater absorption than samples treated at a lower temperature.
Furthermore, sucrose samples treated at a lower pH have greater absorption levels than samples treated with higher pH levels. Figure 3:This graph represents the concentration and absorbance levels of the glucose standards in grey. The blue and orange respectively represents the absorbance levels and calculated glucose concentrations of Coke and Gatorade. Furthermore, the linear trend line indicates the glucose’s line of best fit, whilst it was also used to calculate the glucose concentration within the Coke, Gatorade and Sucrose samples. Figure 4:Sample (A2-A1)Absorbance Difference Diluted Concentration(mM) UndilutedConcentration(mM) Glucose Concentration(mol/L) Glucose Concentration(g/100mL)Coke 0.455 2.29 229.00 0.229 4.13Gatorade 0.129 0.65 65.00 0.065 1.18Coke (Diluted)= 2.29mM Coke (Undiluted)= 2.29 X 100 = 229.00 mMmol/L= 229.001000=0.229 mol/LMolar mass of Glucose= 180.16g/L=molL X gmol= 0.229 X 180.16= 41.25gg/100mL= 41.25/10 = 4.125g/100mLGatorade (diluted)= 0.65mMGatorade (undiluted)= 0.65 X 100 = 65.00mMmol/L=65.001000=0.065mol/LMolar mass of Glucose= 180.16g/molg/L = molL X gmol= 0.065 X 180.16= 11.72g/100mL= 11.72/10 = 1.17g/100mL Due to these results, Coke contains 4.125 grams of glucose per 100mL, whilst Gatorade contains 1.17 grams of glucose per 100mL.
Evidence found from conducting this experiment illustrated that Coke had a greater glucose concentration than Gatorade, with Coke having an observed concentration of 4.125g/100mL whilst Gatorade has 1.17g/100mL concentration. These results fairly support the previous study conducted by Emily E.Ventura, Jaimie N. Davis, and Michael, however the results were slightly deviated, with Coke containing 3.9 grams of glucose per 100mL and Gatorade containing 2.4 grams of glucose per 100mL. According to nutritional labels, Coke contains 10.6 grams of sucrose per 100mL, which therefore opposes the observed data levels of sucrose within Coke (Coca-Cola, 2017). This is evident that the sucrose added to Coke has been hydrolysed into glucose and fructose. Furthermore, circumstances such as the location the products were produced from, the amount and type of sugar added into drinks must be considered as it varies between and can be the reason why the results between the two samples are different.
Due to the spectrophotometer measuring the absorbance levels and not the concentration of glucose directly, this meant that the glucose concentration levels were calculated subsequently. The glucose within the sample can be accredited to sucrose hydrolysis due to the acidic environment of Coke as it has a pH of 2.40. As seen from Figure 5, the observed Gatorade levels differs from the nutritional labelling of Gatorade, as manufacturers state that there is 0.5g/100mL within each can, however the observed levels state there is 1.17g/100mL. The difference between the two experiments is due to a likely incompletion of hydrolysis of sucrose within Gatorade’s acidic environment of pH 2.97. The acidity of Coke and Gatorade has been influenced by phosphoric acid and citric acid, which can lower pH and act as a catalyst for sucrose hydrolysis (Kitchens, et. al., 2007).In contradiction, without enzyme invertase present under neutral conditions, the sucrose would remain in its disaccharide form whilst the hydrolysis rate would significantly decrease ( Pan, Y., et al., 2007).
As seen in Figure 2, it is signifying that the observed sucrose added to Coke and Gatorade has been hydrolysed into glucose and fructose. Figure 3 represents the absorbance levels of sucrose samples measured within the spectrophotometre. It was observed that the samples treated at a lower pH and a higher temperature had greater absorbance levels rather than the samples containing a higher pH and a lower temperature. Both random and methodical errors have played a role towards slightly skewing the line of best fit recorded towards glucose concentrations between Coke and Gatorade. Random errors such as incorrect equipment use (readings of the spectrophotometer, measurements with the pipette and incorrect timing) may have played a role. Figure 3 suggests that at 2mM and 4 mM could have been due to random errors as it did not align with the line of best fit. With this error occurring, it means that there is a greater absorption value for the 2mM and 4mM sample, affecting the linear trend-line.
Due to this error, the line of best fit had to be slightly assumed in order for the line to pass through the 0 point on the graph. Due to the incorrect handling of equipment during the experiment, a methodical error could have risen, however repeating the experiment would have decreased the errors obtained within the data. The results found within this experiment are appropriate to future findings correlating glucose and sugar to obesity and other health concerns. In order to improve research, investigating glucose concentrations within a broader variety of drinks and brands could help observe the conditions and determine which drink performs sucrose hydrolysis the most efficiently. Further research may also decrease the possibility of customers being misled by nutritional labels and gain more control over their glucose intake, preventing arising metabolic health complications.