MIDDLE EAST TECHNICAL UNIVERSITY FOOD ENGINEERING DEPARTMENT FDE 310 FOOD MATERIALS LABORATORY Experiment 5 Protein Determination Submitted to : Oya Nihan Uncu Section 2/Group 2 Merve Aylin Aydoğdu Büşra Karahan Özge Önder Elif Gökçen Sakar Burcu Başak INTRODUCTION Kjeldahl method was used in laboratory to determine the amount of protein in Feta Cheese. Determination of protein content in feta cheese, there are three steps which are digestion, neutralization and titration. More than 90 % of protein containing samples and over 60 % of all other nitrogen containing samples can be analyzed using this basic procedure. (Persson,2008) In the digestion step, the decomposition of nitrogen in organic samples utilizes a concentrated acid …show more content…
H2SO4 • Catalyst: potassium sulphate (K2SO4), copper (II) sulphate pentahydrate (CuSO4.5H2O) • NaOH (40%) • 0.1 N HCl solution • Boric acid (4%) • Indicator: methyl red (200 mg make up to 100 ml with %95 ethanol ) 1 gram Feta Cheese was used as a sample in this experiment. First of all, the experiment was started with the digestion phase which was performed by mixing 10g potassium sulphate and 0.5 g CuSO4 solution that acts as catalyst, and added 20ml conc. H2SO4. The digestion unit temperature was set to 420±10°C and preheated for 15 minutes. Then, it was heated continuously at least 2 hours till a clear colorless solution was obtained. After finishing the heating process, the tubes which contained the mixture were left to cool and removed from the digestion unit. 50ml of distilled water was added to the digestion tube and 70ml of NaOH was added by the NAOH pump of the system. When the distillation was done, 50ml boric acid (4%) was added into the 250 ml flask. Steam distillation was applied and boric acid & ammonia were obtained. In order to determine the nitrogen content , titration was done with 0.1 N HCl, using a suitable indicator, two or three drops of methyl red, to determine the end-point of the reaction. The end point was indicated by the changing color to lilac or purple. Finally, the amount of HCl was recorded to calculate the percentage of …show more content…
However according to label of La vache qui rit cheese, it should contain 19 % protein content. We could not find the same result as in the literature however protein content of different feta cheeses taken from different regions varies. Besides, error may occur as a result of problems in laboratory or problems due to human error. These difference may be caused by sample size and type incompatibility with amounts and types of acid, salt or catalyst used; contaminated samples, leaks in apparatus connections, inadequate sodium hydroxide addition or sodium hydroxide carry over, and calculation errors.
There was a strong odor similar to the smell of vinegar given off. After the solution was heated and the solid dissolved, 0.2 mL of hydrobromic acid was added to the test tube. The solution turned a bright yellow color after the hydrobromic acid was added. The solution was heated in a hot water bath for 5-10 minutes and then let cool. After heating, the
A milk-based, litmus broth tube is incubated and observed after 48 hours. Observations include lactose fermentation without gas as well as with gas, the reduction of litmus, casein protein coagulation and casein and protein hydrolysis. These characteristics were all determined based on the color of the solution and the production of a curd, the curds density and the production of a gas. To determine the density of the curd, the tube was slightly turned to see rather or not it was mobile or concentrated towards the bottom. 2.3 Carbohydrate Fermentation of Lactose, Sucrose and
There are few vegetables and fruits that turns to the color brown if their surface is exposed to oxygen. Once the veggies or fruits been exposed to oxygen, then the browning begins to appear, and electrons and hydrogen will be removed. This happens because of an enzyme called catechol oxidase. The enzyme will act on its substrate catechol to form a yellow compound which then reacts with the oxygen in the air and change into benzoquinone. The more concentration of the enzyme, the more browning appears.
Testing for the Presence of Macromolecules in McDonald’s Happy Meals Clayton Wagoner MST Biology White 4 duPont Manual High School Introduction Carbohydrates, lipids, proteins, and nucleic acids are organic molecules found in every living organism. These macromolecules are large carbon based structures. The macromolecules are assembled by joining several smaller units, called monomers, together through a chemical reaction called dehydration synthesis. The resulting polymer can be disassembled through the complementary process called hydrolysis.
Glacial acetic acid and acetic anhydride were added to the mixture while refluxing, which converted the lime colored solution into a clear mixture. The flask was cooled in an ice bath and the solution
Weighed 1 gram of NaC2H3O2 and mixed it with ionized water. Boiled 12 mL of 1.0M Acetic Acid added into a beaker containing the sodium carbonate on a hot plate until all the liquid is evaporated
Leah Romero 10/30/2017 Conclusion Lab 3 Chem 102L In lab 3, fundamentals of chromatography, the purpose was to examine how components of mixtures can be separated by taking advantage of different in physical properties. A huge process in this lab was paper chromatography, which was used to isolate food dyes that are found in different drink mixes. The different chromatograms of FD&C dyes were compared to identify which dyes are present in each of the mixes.
LABORATORY REPORT Activity: Enzyme Activity Name: Natalie Banc Instructor: Elizabeth Kraske Date: 09.26.2016 Predictions 1. Sucrase will have the greatest activity at pH 6 2. Sucrase will have the greatest activity at 50 °C (122 °F) 3.
As a result, beer attained a positive result. Starch and glycogen produced a negative result because they are polysaccharides and don’t have the aldehyde functional group. Distilled water contains no monosaccharides and has to ability to reduce the copper ions (Cu+) and
LABORATORY REPORT Activity: Enzyme Activity Name: Natalie Banc Instructor: Elizabeth Kraske Date: 09.22.2016 Predictions 1. Sucrase will have the greatest activity at pH 6 2. Sucrase will have the greatest activity at 50 °C (122 °F) 3. Sucrase activity increases with increasing sucrose concentration Materials and Methods Effect of pH on Enzyme Activity 1. Dependent Variable amount of product (glucose and fructose) produced 2.
1.1 Abstract The purpose of quantitative analysis of protein using a spectrophotometer is to measure the concentration of proteins in a given sample. The experiment is conducted by laboratory method (Biuret Test) and using spectrophotometer to analyze the absorbance of reactants at 540 nm, hence determining the concentration of the proteins in a given sample. The purpose of stopped enzyme assay to study B-galactosidase is to determine the effect of temperature and concentrations of substrate on enzyme activity.
This verified the formation of the major products. Overall, one can say that the experiment was
The equation of the reaction between sodium hydroxide and ethanoic acid is as follows: CH3COOH + NaOH → CH3COONa + H2O We can measure the end point of titration process and we can also measure the amount of reactants. The concentration of ethanoic acid in the vinegar can be determined through stoichiometric calculations, Using the values obtained from the titration, and also the chemical equation as a reference. Phenolphthalein indicator is used in this acid-base titration Equipment and materials:
Its pH is greater than 7 and turns red litmus paper into blue. Acid- base neutralization is done by adding an acid to a base or a base to an acid until the substance has equal hydrogen and hydroxide ions. This is used to determine unknown concentration of a
The ammonia: 1-butanol (1:1) solvent was the appropriate solvent to use for the column chromatography of food dye because it exhibited the properties of a good solvent system. A total 8 colored eluents were collected. The eluents had colors of pink, dark red, dark blue, dark green, light green, yellow, orange and light yellow respectively and