Abstract: Different compounds were tested to see their ability to inhibit polyphenol oxidase and prevent the browning from ortho quinones of fruits and vegetables. Five compounds were tested to see which compound produced more brown product and which compound showed higher inhibition. The production of benzoquinone was tested through a 420 nm spectrophotometer. Compounds A and D showed the most inhibition for the production of benzoquinone. Introduction: Many consumers today prefer to purchase prepackaged fruits and vegetables, but are often surprised by the drastic price of these pre-sliced products (Chen et al., 2015). Polyphenol oxidases is a naturally occurring enzyme that causes browning because of its enzymatic activity. Due to the …show more content…
First we gathered and labeled 6 test tubes, five for the compounds and one for the control, which was water. We used 5 compounds with 3 replicates per compound to accurately measure the responses to the different inhibitor concentrations. We added 2 drops of inhibitor in tubes 1-5. Then we added 5mL of distilled water in tubes 1-6 and 8 drops of potato extract. We used potato extract because of its ability to produce benzoquinone. Next we added 8 drops of substrate, which was the catechol. This was replicated 2 more times to get a total of 3 replicates per compound. For each experiment per compound we increased the amount of inhibitor in intervals of 2, from 2 to 10. We made sure to keep the volume constant in all 6 tubes. So as we added more drops of inhibitor, we added less drops of water to maintain the same volume. Once everything was added to the test tubes, we waited for 5 minutes for the reaction to occur. After the 5 minutes were complete, we transferred 2mL of the samples to a cuvette and measured the absorbance at 420 nm in a spectrophotometer. The spectrophotometer measures the production of benzoquinone for each
Data from Table 1. confirms the theory that as the concentration of glucose increases so will the absorbance of the solution when examined with the glucose oxidase/horseradish peroxidase assay. Glucose within the context of this assay is determined by the amount of ferricyanide, determined by absornace, which is produced in a one to one ratio.1 Furthermore when examining the glucose standards, a linear calibration curve was able to be produced (shown as Figure 1). Noted the R2 value of the y = 1.808x - 0.0125 trend line is 0.9958, which is statistically considered linear. From this calibration curve the absorbance values of unknowns samples can be compared, and the correlated glucose concentration can then be approximated.
In the lab, Inhibiting the Action of Catechol Oxidase we had to investigate what type of enzyme inhibition occurs when an inhibitor is added. Catechol oxidase is an enzyme in plants that creates benzoquinone.Benzoquinone is a substance that is toxic to bacteria. It is brown and is the reason fruit turns brown. Now, there are two types of inhibitors, the competitive inhibitor and non-competitive inhibitor. For an enzyme reaction to occur a substrate has to bind or fit into the active site of the enzyme. In competitive inhibition there is a substrate and an inhibitor present, both compete to bind to the active site. If the competitive inhibitor binds to the active site it stops the reaction. A noncompetitive inhibitor binds to another region
Table 6 shows the results of the biochemical tests. The isolate can obtain its energy by means of aerobic respiration but not fermentation. In the Oxidation-Fermentation test, a yellow color change was produced only under both aerobic conditions, indicating that the EI can oxidize glucose to produce acidic products. In addition to glucose, the EI can also utilize lactose and sucrose, and this deduction is based on the fact that the color of the test medium broth changed to yellow in all three Phenol Red Broth tests. These results are further supported by the results of the Triple Sugar Iron Agar test. Although the EI does perform fermentation of these three carbohydrates, it appears that this bacterium cannot perform mixed acid fermentation nor 2,3-butanediol fermentation due to the lack of color change in Methyl Red and Vogues-Proskauer
In this experiment the enzyme peroxidase and the substrate hydrogen peroxide were not mixed initially, instead they were both placed in separate tubes and were incubated at a specific temperature, to prevent hydrogen peroxide from undergoing any reaction with peroxidase until they both acquire the required temperature.
Materials used in the experiment included 5-7 g of the potato tissue, 50ml of 2.0M phosphate buffer coffee filter and guaiacol dye.
PGLO Write Up Purpose The full on purpose and meaning of the PGLO lab was to see and watch transformation happen and to understand it. Transformation is when there’s a genetic alteration in a bacterial cell, or a alternation in a cell.
Analyze each fraction by spotting 10 times with capillary tubes on a TLC plate, which is exposed to iodine vapor for 15 minutes.
The cultivation of the Portobello mushroom displays a unique homothallic method of reproduction, which is advantageous in that it can breed any spore that lands on a suitable substrate. The mushroom is cultivated in 6 phases: composting (phase I), composting (phase II), spawning (phase III), casing (phase IV), pinning (phase V) and cropping (phase VI). The cultivation requires little land and can grow on substrates of industrial and agricultural waste. During cultivation, the farmer must take precautions in order to avoid conditions (such as soft rot) that affect the quality of the mushroom in storage and delivery. Furthermore, different supplementation during the cultivation process can prevent issues with yield, shelf life, quality and flavor of the mushroom. Postharvest browning is one of the main issues beyond cultivation. In order to properly preserve and distribute the mushrooms, measures such as modified atmosphere packaging, coating, washing, refrigeration, and ozone treatments have been researched to improve the process.studied.
Enzymes are catalysts which lower the activation energy of chemical reactions, thus making them occur more rapidly. Enzymes are in constant use because of their ability to increase the rate of the reaction without permanent alteration. Each enzyme has a different rate of reaction as well as a maximum speed; you can find this number by adding substrate into the concentration until the speed remains constant. The maximum velocity divided by two gives you the Km. In this experiment the efficacy of the enzyme peroxidase was tested.
It changes from blue to red with acids but loses its colour in the presence of certain chemicals, one of which is vitamin C. DCPIP solution can be used to test for the presence of vitamin C in foods. Hypothesis Orange juice has the highest content of vitamin C. Citrus fruits have a higher content of vitamin C. The orange and lemon juice contain more vitamin C than the pineapple juice. Furthermore, as lemons are more acidic than oranges, I predict that the orange juice will contain more vitamin C than the lemon juice. Vitamin C affects, the ph the more vitamin C the higher the ph. Variables Independent Variables Different fruit juices (Pineapple, orange and lemon).
Lipids are a major source of energy and provide essential lipid nutrients. In many food products the lipid component plays a major role in determining the overall characteristics, such, as flavour, texture, mouthfeel and appearance (Ross & Smith, 2006). However, fats, oils and lipid-based products deteriorate during heat processing, distribution and long term storage. The chemical deterioration is as a result of lipid oxidation. In some chesses, a limited amount of lipid oxidation is desirable for the generation of a characteristic taste or smell (Sun et al., 2011). On the other hand it is undesirable in high lipid or fat containing food products. Lipid oxidation is a major concern to the food industry due to the increasing emphasis on the use of polyunsaturated vegetable and fish oils, and discontinuing the use of synthetic antioxidants. Unsaturated fats are used extensively in the formulation of many food products and these are the most susceptible to oxidation. Lipid oxidation can lead to several changes to food products which affects shelf-life and consumer acceptance. These include development of rancid flavours and aromas, changes in colour and texture, and a decline in the nutritional value of food products (Hidalgo & Zamora, 2000; Morales & Jaménez-pérez, 2001). Lipid oxidation products decompose lipid soluble vitamins such as vitamin A, D, E and K, and its pro-vitamins carotenes resulting in nutritional losses in food products (Rahman, 2007). In addition, the oxidation of fats in foods can lead to the accumulation of toxic compounds such as peroxides and aldehydes. These are potentially detrimental to human health when consumed in high concentrations and have been implicated in the development of several diseases includi...
Nature teaches us from the beginning to judge and make choices about our environment based to a large extent on color. It influences sweetness perception, food preference, pleasantness and acceptability. Color has been shown to replace sugar in foods and take on the role of sweetness. It interferes with judgments of flavor and intensity of foods (Clydesdale). In the earliest records of man as a food gatherer, the colors in roots, berries and fruits were understood as healthy nutrition. Even today, in organic and natural fruits and vegetables, colors are natural and indicative of many nutrients contained in them. However, food that is processed now with artificial color is intended to fool people into thinking that those colors are nutritious. And the companies that process that food are successful in changing that thinking. A recent discovery of an...
This clearly shows that the fruits and vegetables play a vital role in maintaining our good health. Fruits and vegetables are seasonal and grown in different parts of our country. They need to be stored for longer period and transported to different places. It makes necessary for us to find out whether there is any damage to the useful contents of the fruits and vegetable during the storage and transportation or due to some preservatives or other factors and what kind of nutrients, minerals, etc. are present in their juices. With this idea in mind, the project has been undertaken.
The colour is the first impression consumers have of any meat product and often is their basis for product selection or rejection (Deda et al., 2007). As shown in figure, the pleasing pink shade is the result of the chemical reaction between compounds derived from added nitrite/nitrate and the naturally occurring red myoglobin (MbFeII) leading to the simultaneous formation of the bright red nitrosylmyoglobin (MbFeII NO), in which an axial ligand nitric oxide (NO) is coordinated to the central FeII in heme (Møller and Skibsted, 2002). Nitrate is necessary in a long curing process to act as a source of nitrite by the action of the nitrate reductase enzymes present in by bacteria (Marco et al., 2006). Nitrite requires one less step in stabilization of colour. Nitrous acid is generated when nitrite comes in contact with water. The NO derived from nitrous acid can bind to myoglobin (Fe2+), forming NO-Mb and oxidizes it to MetMb. NO-MetMb is brown and under anaerobic conditions, it can be slowly reduced to red NO-Mb, then converted to pink NO-hemochrome during cooking (Bryan, 2009), which is a pink pigment (Honikel 2008). When cured meat is spoiled or exposed to light and oxygen, the heat stable pink colour changes to brown, due to
Artificial food pigments could be classified according to their color to four main groups, blue, red - orange, yellow and green – white group. Table 1 shows the most used food pigments in each group and their relative ADI values and applications. The lowest ADI values were reported to the red to orange group of pigments with ADI values between 0.1 and 0.8 mg/kg b.w. making this group the most dangerous pigments, followed by the green-white group (with ADI values between 0.1 and 0.8 mg/kg b.w), then the yellow group and finally the blue group is the less dangerous