SPRING 2018: Biochemistry for Health Majors Lab #3: Carbohydrates 1. Introduction Carbohydrates in foods are important for their structural, functional, and nutritional properties, and for their participation in many types of chemical reactions. Polysaccharides exist in foods as a diverse array of naturally occurring polymers and a wide variety of chemically modified forms. The physical state and chemical nature of polysaccharides influence the texture, appearance, and mouth feel of foods. The products of starch hydrolysis (corn syrup solids) vary in viscosity, taste, and chemical reactivity as a function of the degree of polymerization of the sugars/oligosaccharides present. Sugars exist as either reducing or non-reducing forms, which differ markedly in reactivity. Sucrose, commonly known as table sugar, is a non-reducing disaccharide composed of an alpha-D-glucose molecule and a beta-D-fructose molecule linked by an alpha-1,4-glycosidic bond. When this bond is cleaved in a hydrolysis reaction, an equimolar mixture of glucose and fructose is generated. Although sucrose is a nonreducing sugar, processing or storage of sucrose-containing foods under acidic conditions can yield sufficient hydrolysis of sucrose that carbonyl-amine and other reactions involving reducing sugars can take place. Even storage of low- or intermediate-moisture foods containing acidic compounds (e.g. citric or phosphoric acid) can induce browning due to sucrose hydrolysis. The fructofuranosidic linkage of sucrose is more susceptible to hydrolysis than many other glycosidic bonds. This exercise is designed to illustrate the acid catalyzed hydrolysis of sucrose. The hydrolysis ('inversion') of sucrose, completely or partially, to glucose and fructose provides sweet syrups that are more stable (i.e. less likely to crystallize) than pure sucrose syrups. This hydrolysis reaction has historically been performed using acid hydrolysis (e.g. golden syrups). However, with the growth in the market for colorless invert syrups, which are costly to produce using acid due to the downstream purification needed, the use of enzymes has become more popular. Sucrose can be hydrolyzed in the presence of an enzyme called invertase. The official name for invertase is beta-fructofuranosidase, which implies that the reaction catalyzed by this enzyme is the hydrolysis of the terminal nonreducing beta- fructofuranoside residues in beta-fructofuranosides. Invertase is mainly used in the food industry where fructose is preferred over sucrose because it is sweeter and does not crystallize as easily. A wide range of microorganisms produce invertase and can, thus, utilize sucrose as a nutrient. Commercially, invertase is biosynthesized chiefly by yeast strains of Saccharomyces cerevisiae or Saccharomyces carlsbergensi. For health and taste reasons, its use in food industry requires that invertase be highly purified. 2. Objective The objectives of this experiment are: a. To compare the quality of sugar hydrolysates obtained by acid hydrolysis methods and illustrate their influence on reactivity, sweetness, and viscosity. 3. Materials Acid Hydrolysis of Sugars • 1 M HCl. • 1 M NaOH • 0.3 M solution of sucrose freshly prepared. • Reducing sugar color reagent: DNS • 40°C, 50°C, 70°C water baths 4. Methods Acid Hydrolysis of Sugars 1. Place the sugar solution into each tube. 2. Retain one tube as a control, and then place the rest of the tubes (including the blank) in one of each water bath at the different temperatures (40, 90°C). With accurate timing, remove tubes after 5, and 20 minutes. Cool immediately on ice. 3. Color reaction: when all tubes have been removed, add 0.5 mL of 3,5dinitrosalicylic acid (DNS) reagent to each (including the blanks and 0-time controls). Cap tightly, mix, and place in a boiling water bath for 10 minutes. 4. Cool on ice or in cold water, and then add 4.0 ml of distilled water to each Read the absorbance at 540 nm after zeroing the spectrophotometer with the blank. 5. Results a. Describe in detail how would you prepare the solutions used in this lab (show your calculations): b. Plot absorbance as a function of time at each temperature for each procedure (acid hydrolysis). Calculate the slope and use it to discuss the influence of temperature and concentration on each reaction. Run A0 A1 A2 A3 A4 A5 0.3M Sucrose, mL 1 0.5 0.5 1 1 0 Run B0 B1 B2 B3 B4 B5 0.3M Sucrose, mL 1 0.5 0.5 1 1 0 Water, mL 1 1 0.5 0.5 0 1 1M HCl, mL 0.0 0.5 1 0.5 1 1 Water, mL 1 1 0.5 0.5 0 1 1M NaOH, mL 0.0 0.5 1 0.5 1 1 What differences did you see with sucrose and acid/Base-hydrolyzed sucrose? Why? 9/18/2014 Rubric Rubric Name Copy of Lab Report Grading Rubric Description This is the rubric which describes how lab reports will be graded Rubric Detail Levels of Achievement Criteria Poor Beginning Developing Accomplished Exemplary Abstract 0 Points 2 Points 3 Points 4 Points 5 Points Missing Several major aspects of the experiment are missing, student displays lack of understanding on how to write an abstract. Abstract misses one or more major aspects of carrying out the experiment or results. Abstract references most of the major aspects of the experiment, some minor details are missing Abstract contains references to all major aspects of carrying out the experiment and the results, well‑ written. 0 Points 2 Points 3 Points 4 Points 5 Points Missing Very little background information provided or information is incorrect. Key concepts, key question, and experiment importance is missing. Some introductory information, but still missing some major points. Introduction is nearly complete, missing some minor points. Introduction complete and well‑written; provides all important background concepts, experimental importance, and key question of the experiment. 0 Points 2 Points 3 Points 4 Points 5 Points Missing Missing several important experimental details or not written in paragraph format. Most steps are missing or are confusing. Written in paragraph format, still missing some important experimental details; most are confusing and lack detail. Written in paragraph format, important experimental details are covered. Some lack detail or confusing. Well‑written in paragraph format, all experimental details are covered. 0 Points 2 Points 3 Points 4 Points 5 Points Missing Hand drawn structures. Drawn with Chemsketch but structure is missing most components, sloppy. Drawn with Chemsketch but structure is missing some components, less sloppy. Structure is drawn and labeled properly. Introduction Experimental Chemical structures https://morgan.blackboard.com/webapps/rubric/do/course/manageRubrics?dispatch=view&context=course&rubricId=_5875_1&course_id=_72409_1 1/2 9/18/2014 Rubric Results: data, figures, graphs, tables, etc. 0 Points 2 Points 3 Points 4 Points 5 Points Missing Figures, graphs, tables contain errors or are poorly constructed, have missing titles, captions, or numbers, units missing or incorrect, etc. Most figures, graphs, tables OK, some still missing some important or required features. All figures, graphs, tables are correctly drawn, but some have minor problems or could still be improved. All figures, graphs, tables are correctly drawn, are numbered and contain titles/captions. Discussion 0 Points 2 Points 3 Points 4 Points 5 Points Missing Presents an illogical explanation for findings and does not address any of the questions suggested. Presents an illogical explanation for findings and addresses few questions. Presents a logical explanation for findings and addresses some of the questions. Presents a logical explanation for findings and addresses most of the questions. 5 Points 4 Points 3 Points 2 Points 0 Points All important conclusions have been clearly made, student shows good understanding. All important conclusions have been drawn could be better stated. Conclusions regarding major points are drawn, but many are misstated, indicating a lack of understanding. Conclusions missing or missing the important points. Missing 5 Points 4 Points 3 Points 2 Points 0 Points All grammar and spelling are correct and very well‑ written. Only one or two errors, mature, readable style More than two errors, generally readable with some rough spots in writing style. Very frequent grammar and/or spelling errors. Writing style is rough and immature. Missing Conclusion Grammar/Spelling View Associated Items Print Close Window https://morgan.blackboard.com/webapps/rubric/do/course/manageRubrics?dispatch=view&context=course&rubricId=_5875_1&course_id=_72409_1 2/2 NAME sugar lab DATE 55 LAB PARTNER LOCKER/DESK NO. COURSE & SECTION NO. * Calaulabion : sugar melder massa aut 342.3 g/mol E group #1 ho -0.024 A A1 0.029 ( Bo - 2000 0.009 B1 o.oul A2 - 0.002 B2 o.197 B3 -> 2 라 0.187 ج # A3 0034 By -0.096 Au ) 0.002 A50,000 B5-7000 Egroup # #2 Bo->-0.002 A A o - 0.028 B 1 0.047 A1 -> 0.003 Az - Fot3 0.020 Az - 0.001 Au -> Groot 0.007 B2-70.056 B3 0.048 By-> 0.142 Bb -> 0.000 SIGNATURE DATE WITNESS/TA DATE A5 -> 0.000 THE HAYDEN-MCNEIL STUDENT LAB NOTEBOOK NOTE: INSERT DIVIDER UNDER COPY SHEET BEFOR
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