Fruit Browning Lab Report

And finally into test tube 3, I pipetted 1.0 ml turnip extract and 4.0 ml of water. The contents of test tube 1 was poured into a spectrometer tube and labeled it “B” for blank. “B” tube was now inserted it into the spectrometer. An adjustment to the control knob was made to zero the absorbance reading on the spectrometer since one cannot continue the experiment if the spectrometer is not zeroed. A combination of two people and a stop watch was now needed to not only record the time of the reaction, but to mix the reagents in a precise and accurate manner. As my partner recorded the time, I quickly poured tube 3 into tube 2. I then poured tube 2 into the experiment spectrometer tube labeled “E” and inserted it into the spectrometer. A partner then recorded the absorbance reading for every 20 seconds for a total of 120 seconds. After the experiment, a brown color in the tube should be observed to indicate the reaction was carried out. Using sterile techniques, any excess liquid left was disposed

In this experiment, 4 grams of peeled turnip was used to prepare the enzyme extract opposed to the 1 gram of turnip suggested by Fundamentals of Life Science. Along with the change to the amount of turnip used, the amount of 0.1M phosphate buffer used to prepare the enzyme extract was changed from 50mL to 30mL. The affect of temperature on enzyme activity was not

We used a spectrophotometer to measure how much blue light energy is absorbed by benzoquinone. As the product solution gets browner that means the more benzoquinone was produced. We used the change in absorbance over a period of time was used to calculate the average reaction rate of catechol oxidase when exposed to different temperatures and pHs. We hypothesized that the benzoquinone absorbance rate would be faster when the pH added to the cuvettes were greater than the pH of the potato tissue. Our second hypothesis states that we believe that enzymatic reaction rates would have the slowest reaction at 80 degrees Celsius, slightly faster at 4 degrees Celsius, moderate at 37 degrees Celsius, and the fastest at 25 degrees Celsius. We based our hypothesis on the fact that potatoes grow in temperatures around 25 degrees Celsius better than any other temperatures. Therefore, we think that catechol oxidase activity would be higher when the temperature is around 25

Catechol, in the presence of oxygen is oxidized by catechol oxidase to form benzoquinone (Harel et al., 1964). Bananas and potatoes contain catechol oxidase that acts on catechol which is initially colorless and converts it to brown (Harel et al., 1964). In this experiment, the effect of pH on the activity of catechol oxidase was conducted using buffers ranging from pH2 to pH10. Two trials were conducted due to the first trial results being altered by an external factor. The results were acquired by taking readings every 2 minutes for 20 minutes from a spectrophotometer and then recorded on to the table. The data collected in the table were then made into graphs to illustrate the influence of pH on the catechol oxidase catalyzed reaction. After analysis, the data revealed that pH did have a significant influence on the enzyme as recorded by absorbance per minute. However, the data was collected was not accurate due to external factors, thus the results are debatable and should be experimented again for validation.

The purpose of this experiment is to learn the effects of a certain enzyme (Peroxidase) concentration, to figure out the temperature and pH effects on Peroxidase activity and the effect of an inhibitor. The procedure includes using pH5, H202, Enzyme Extract, and Guaiacol and calibrating a spectrophotometer to determine the effect of enzyme concentration. As the experiment continues, the same reagents are used with the spectrophotometer to determine the temperature and pH effects on Peroxidase activity. Lastly, to determine the effect of an inhibitor on Peroxidase, an inhibitor is added to the extract. It was found that an increase in enzyme concentration also caused an increase in the reaction rate. The reaction rate of peroxidase increases at 40oC. Peroxidase performed the best under pH5 and declined as it became more basic. The inhibitor (Hydroxy-lamine) caused a decline in the reaction rate. The significance of this experiment is to find the optimal living conditions for Peroxidase. This enzyme is vital because it gets rid of hydrogen peroxide, which is toxic to living environments.

Before the start of the experiment, the theoretical yield was to be calculated. First, the limiting reagent was determined from the reagents by comparing the amount of moles. Among the three reagents involved in this experiment - camphor, sodium borohydride, and methanol, camphor was found to be the limiting reagent. The moles of camphor was less than the combined moles of the other two reagents. The theoretical yield, which is the amount of product that could be possibly produced after the completion of a reaction (“Calculating Theoretical and Percent Yield”), was found to be 0.25 g. Once the product was achieved, a percent yield of 97% was determined. As a result, the reduction of camphor to isoborneol was successful.

This is because each kind of apple has a different concentration of catechol oxidase (Daniela Finkel, 2013). Therefore, each apple has a unique speed at which it will produce benzoquinone, and turn brown.

The aim of this study was to test the rate of reactivity of the enzyme catalase on hydrogen peroxide while subject to different concentrations of an inhibitor. The hypothesis was that hydrogen peroxide will be broken down by catalase into hydrogen and oxygen, where a higher concentration of inhibitor will yield less oxygen, resultant of a lower rate of reaction. Crushed potato samples of equal weight were placed in hydrogen peroxide solutions of various temperatures. The results showed that less gas was produced as the concentration of the inhibitor rose. This Is because more enzymes were inhibited, and so less active sites were available for reaction.

In the exercise # 2 we observed the effect of substrate concentration, enzyme concentration, pH and temperature on enzyme activity. All the data showed that once potato extract was added to catechol and water the reaction varied dependent on the level of catechol. As in

The use of multiple test tubes and Parafilm was used for each experiment. Catechol, potato juice, pH 7 phosphate buffer, and stock potato extract 1:1 will be used to conduct the following experiments: temperature effect on enzyme activity, the effect of pH on enzyme action, the effect of enzyme concentration, and the effect of substrate concentration on enzyme activity. For the temperature effect on enzyme activity, three test tube were filled with three ml of pH 7 phosphate buffer and each test tube was labels 1.5 degrees Celsius, 20 °C, and 60 °C. The first test tube was placed in an ice-water bath, the second test tube was left at room temperature, and the third test tube was placed in approximately 60°C of warm water. After filling the test tubes with three ml of the

The inhibitors were prepared by conducting them on a hot plate at a temperature of about 90℃. Instead using the oven, using hot plate can help to save time and space for the experiment to be conducted as limitation of lab equipment in preparing the chemicals. The individual chemicals, EVA, MCH and Toluene are measured separately of its respective volume and weightage in accordance to the manipulated percentage composition. The unit for the EVA is grams of mass while MCH is in mL and toluene and butanol in mL. The total volume of inhibitor used is 0.4g. Thus, for example, if the percentage composition of sample prepared is 50% EVA, 10% MCH and 40% Toluene, then 0.2 g EVA is measured using a mass balance, 0.04 mL of MCH is measured using a micropipette and 0.16 mL of Toluene is measured using a micropipette.

a) Inhibition: occurs as a result of oxidants competing with the FC reagent or air oxidation after the sample is made alkaline. To avoid this, we add FC reagent before the alkali. b) Additive effect: occurs from unanticipated phenols, aromatic amines, high sugar levels or ascorbic acid in the extract. The following protocol is a modified version of that described by Gillespie and Ainsworth and is a rapid, small scale, high throughput

With the desire of wanting to know how to increase the enzyme’s activity rate, the experimenters formulate a question that is which temperature will cause the potato enzyme to decompose the most hydrogen peroxide? In order to find the answer to this inquiry, experimenters started the procedure by preparing four different potato samples, where there were, hot, cold, room temperature, and baked potato samples. Each sample was half of two Idaho potato, which was cut into fourths. Then, each group of potatoes were examined when each section was submerged in 150 mL of hydrogen peroxide in individual beakers. The results were recorded based on the physical appearances of each reaction.

Tyrosinase and DOPA are key elements in making melanin. In order to model this reaction, we obtained the enzyme from a 15 g peeled potato and placed the chilled enzyme into five pairs of tests tubes with different pHs to measure the amount of melanin produced. The blank test tubes consisted of 4.9 ml of pH 6.0 phosphate buffer in the blanks, 0.1 ml tyrosinase extract, and a pH of 3,5,7,9 or 11. Each reacting test tube consisted of 3.9 ml of pH 6.0 phosphate buffer, 0.1 ml tyrosinase extract, pH of 3,5,7,9 or 11 and 1.0 ml of DOPA. Each test tube was measured with a spectrophotometer at a wavelength at 450 nm at time 0 and every two minutes for fourteen minutes. A blank was put in before measuring each test tube with the DOPA. After

Enzymes have a substrate: the substrate for the catecholase enzyme is catechol and oxygen. When the substrate combines with the catecholase enzyme of a potato, the product is a reddish brown color called benzoquinone. This product is what turns fruits and vegetables brown (Briggs and others 2010). Therefore, slowing or stopping the process of would increase shelf life of some food, or at least make the foods appearance appetizing much longer. The equation for this chemical reaction is: