Practical 3 Carbohydrates qualitative 2016 (original) (raw)
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Abstract
AI
This practical focuses on the qualitative determination of carbohydrates, including the structure, classification, and chemical properties of various carbohydrate types such as monomers and polymers. Key tests like the Benedict's test for reducing sugars and the iodine test for starch are outlined, along with necessary reagents and protocols for their execution. The aim is to enable observation and inference regarding the presence and behavior of carbohydrates in biochemical reactions.
Related papers
2020
For complex carbohydrates, such as glycogen and starch, various analytical methods and techniques exist allowing the detailed characterization of these storage carbohydrates. In this article, we give a brief overview of the most frequently used methods, techniques, and results. Furthermore, we give insights in the isolation, purification, and fragmentation of both starch and glycogen. An overview of the different structural levels of the glucans is given and the corresponding analytical techniques are discussed. Moreover, future perspectives of the analytical needs and the challenges of the currently developing scientific questions are included
Activity No. 2 Qualitative Analysis of Carbohydrates
This experiment aims to introduce you with the identification of unknown carbohydrates. The test samples were 1% Dextrin, 1% Galactose, 1% Glucose, 1% Lactose, 1% Sucrose, 1% Maltose and 1% Starch. The test solutions in the Molisch test were treated with Molisch reagent and concentrated sulfuric acid. In the Orcinol test, test solutions were added with Bial’s reagent and was heated in a flame. For the Seliwanoff’s test, the test solutions were added with Seliwanoff’s reagent and was heated in a water bath. And for the Barfoed’s and Benedict’s tests, the test solutions were added with the reagent. Heated in water bath. In Barfoed’s test, the time was recorded when precipitate forms. Thus, the postive result for Molisch test is purple liquid layer. In the Orcinol’s test the positive result for pentoses is blue or green color and hexoses is yellow or brown color. For Seliwanoff’s test, the postive result is red product. Lastly, for Barfoed’s and Benedicts test were the presence of brick red precipitate.
STARCH IN FOOD. STRUCTURE, FUNCTION and APPLICATIONS
Journal of Texture Studies, 2005
This comprehensive review on starch chemistry and technology applied to food is divided into four parts and 21 chapters. The first part of the book covers starch analysis and modification. In Chapter 1, J. Preiss reviews starch synthesis in plants. The author describes a pathway of starch synthesis suggesting specific functions for starch synthesis and branching enzymes. The paper points to the possibility of producing modified starches through molecular biology techniques. Chapter 2 deals with the analysis of starch structure. E. Bertoft reviews analyses of starch structure focusing on amylopectin as the main substrate, and using enzymic methods. The author stresses the need for improved technology for routine starch component characterization. In Chapter 3, A. Blennow reviews progress in starch bioengineering, emphasizing cross disciplinary approach for starch modification. Bleenow points to the huge potential that biotechnology offers in producing starch with customized functionalities, at low cost and in an environment-friendly way. In Chapter 4, D.P. Butler et al. deal with starch-acting enzymes. The chapter reviews starch-hydrolyzing enzymes and their use for functional changes in starch and starch-based foods. The paper also describes molecular biological strategies used to obtain enzymes with new applications in starch modification. A.M. Donald in Chapter 5 reviews starch structure and functionality, highlighting the role current technology can play in understanding and modifying the structure of starch granule. The chapter by M. Peris-Totajarda in Chapter 6 is about measuring starch in food. Perris-Totajarda reviews regulations pertaining to starch analyses and describes classical and modern methods of analyzing starch in food. The second part of the book deals with the various sources of starch. H. Cornell in Chapter 7, provides a comprehensive review on the functionality of wheat starch. Wheat starch manufacturing, structure and functionality are described. Rheological properties of wheat starch paste and gels are covered, as well as wheat starch modification for application in food industry. In Chapter 8, W. Bergthaller offers a succinct review of developments in potato starch, stressing its unique functional properties. The paper covers rheological properties of potato starch, production techniques and ways to improve potato starch for food applications. The reviews ends with a brief look at future trends, especially in breeding, genetic engineering, organic potato starch and the potential offered by small potato starch granules.
Review on the Analysis Methods of Starch, Amylose, Amylopectinin Food and Agricultural Products
International Journal of Advanced Trends in Computer Science and Engineering, 2020
Starch is one of the biggest components of carbohydrates in food and other biological materials. The main components of starch consist of amylose and amylopectin. The comparison between amylose and amylopectin greatly influences the functional, physicochemical, and pasting properties of starch. Various methods of analyzing starch, amylose, and amylopectin content have been widely studied for various purposes. This review describes several types of quantitative analysis methods for starch, amylose and amylopectin. Quantitative methods to determine starch content include the polarimetry, anthrone, Fourier-transform infrared spectroscopy (FTIR), spectrophotometry, penetrometry, and Luff schoorl. The methods for determining amylose content are spectrophotometry and gravimetry, while the method for determining amylopectin content using X-Ray Diffraction (XRD) and gravimetry. Each method has several advantages and disadvantages so that it can be used to determine the method suitable for materials with certain characteristics.
BIOCHEMISTRY OF FOOD CARBOHYDRATES AND IT'S APPLICATION IN FOOD INDUSTRY
ESSENTIALS OF FOOD TECHNOLOGY AND NUTRITIONAL SCIENCE, VOLUME 4, 2023
Since Carbohydrates constitute the main biomolecule in the human body and are widely distributed in nature, carbohydrates are taken far more frequently than other nutrients. There are many distinct types of carbohydrates that serve a wide range of purposes in a variety of industries, such as food, fashion, pharmaceuticals, etc. A significant amount of non-digestible starch passes through the small intestine without being digested and it produces short chain fatty acids which helps to maintain our gut health. Postprandial glucose rise occurs during the carbohydrate digestion phase when RDS content is high and low postprandial glucose rise occurs when SDS content is high. One such non-digestible carbohydrate is resistant starch (RS), which serves as food for the microorganisms in the large intestine and has a significant prebiotic function. Meals containing RS are hypoglycaemic and have been associated to lowering blood pressure, diabetes, and cardiovascular disease. Alginates, Cellulose, Polysaccharides, and Modified Starch is a crucial component of many large enterprises and is useful in changing food functionality in numerous ways. Owing to consumers who care about the environment, plastic is being replaced by environmentally safe biodegradable plastics and bioplastics, whose production heavily relies on starch.
Experiment 4: Carbohydrates Group 8 Members
Post Experiment Questions: 1) Enumerate at least five (5) qualitative tests used for detection of a carbohydrate in an unknown sample a. Molisch Test b. Benedict's Test c. Barfoed's Test d. Osazone Test e. Seliwanoff's Test 2) What are the reagents used and what are the components of each of these reagents enumerated in number 1 a. Molisch Reagent and Sulfuric Acid o Components: Molisch Reagent-A solution of ∝-naphthol in ethanol. b. Benedict's Reagent o Components: A mixture of Sodium carbonate, Sodium citrate and Copper (II) sulfate pentahydrate. c. Barfoed's Reagent o Components: 0.33 molar solution of neutral Copper acetate in 1% Acetic acid solution. d. Phenylhydrazine Mixture o Components: 0.5 g of Phenylhydrazine hydrochloride, 0.1 gram of Sodium acetate and 10 drops of Glacial Acetic acid. e. Seliwanoff Reagent o Components: Resorcinol and Concentrated Hydrochloric acid 3) Discuss the principle underlying each of the qualitative test enumerated in No. 1. What will positive results show? a. Molisch's Test o Carbohydrates undergo dehydration when heated with concentrated H2SO4 to form furfural derivatives. Furfural derivatives obtained are condensed with alpha-naphthol to give colored compounds hence the presence of carbohydrate is confirmed. The positive result yielded will be a purple ring. b. Benedict's Test o Reduction-reaction is carried out in a weak alkaline medium through the presence of sodium carbonate. CuSO4.7H2O in an alkaline citrate solution is the reagent that would participate in the reduction process. The copper in the Benedict's reagent is reduced to Copper (II) Oxide, which then precipitates. The reducing sugar would be the reducing agent, giving out electrons in the copper-containing reagent and allowing precipitation to occur. c. Barfoed's Test o The reaction is based on the reduction of cupric acetate by reducing monosaccharides and reducing disaccharides. The reaction with disaccharides is slower because disaccharides have to get hydrolyzed first and then react with the reagent cupric acetate to produce cuprous oxide. The positive result will be a brick-red precipitate. d. Osazone Test o Osazone formation is an indication of the presence of reducing sugars. The reaction between phenylhydrazine and the carbonyl group of the sugar form phenylhydrazone,
Form and functionality of starch
Food Hydrocolloids, 2009
Starch is a macro-constituent of many foods and its properties and interactions with other constituents, particularly water and lipids, are of interest to the food industry and for human nutrition. Starch varies greatly in form and functionality between and within botanical species, which provides starches of diverse properties but can also cause problems in processing due to inconsistency of raw materials. Being able to predict functionality from knowledge of the structure, and explain how starch interacts with other major food constituents remain significant challenges in food science, nutrition, and for the starch industry generally. This paper describes our current understanding of starch structure that is relevant to its functionality in foods and nutrition. Amylose influences the packing of amylopectin into crystallites and the organization of the crystalline lamellae within granules, which is important for properties related to water uptake. Thermal properties and gel formation appear to be influenced by both amylose content and amylopectin architecture. While amylose content is likely to have an important bearing on the functional properties of starch, subtle structural variations in the molecular architecture of amylopectin introduces uncertainty into the prediction of functional properties from amylose content alone. Our ability to relate starch granule structure to suitability for a particular food manufacturing process or its nutritional qualities depends not only on knowledge of the genetic and environmental factors that control starch biosynthesis, and in turn granule morphology, but also on how the material is processed.
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Isolation and Characterization of Carbohydrates
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International Journal of Current Microbiology and Applied Sciences, 2021
Starch is one of the important carbohydrates that is available in many food materials. It is a great source of energy for man. Starch in its pure form is odorless, tasteless, soft, and looks white. It is highly soluble in hot water but insoluble in alcohol and cold water. Starch can be simplified into two forms: one is the linear and helical polymer amylose and the other is the branched polymer amylopectin. Food having higher amylopectin content shows great swelling and gelatinization properties (Tao et al., 2019). While food containing higher amylose content shows properties of amorphous materials. Also, food having higher amylopectin, or food having lower amylose, shows a higher rate of digestion (Martens et al., 2018). Due to the presence of amylose and amylopectin, starch has unique functional and physicochemical properties, and these International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 10 Number 01 (2021) Journal homepage: http://www.ijcmas.com
A quantitative starch–iodine method for measuring alpha-amylase and glucoamylase activities
Alpha-amylase (EC 3.2.1.1), which cleaves internal -1,4glycosidic linkages in starch to produce glucose, maltose, or dextrins, and glucoamylase (EC 3.2.1.3), which cuts -1,4and -1,6-glycosidic linkages to release glucose from the nonreducing ends of starch, are widely used in the industrial conversion of starch into sugars. The characterization of -amylases and glucoamylases generally needs to use diVerent chromatography techniques such as paper chromatography [1,2], high-performance liquid chromatography , and thin-layer chromatography . There are mainly two types of assays that are used to determine the activity of -amylase and glucoamylase. One is based on measuring the amount of reducing sugars by the dinitrosalicylic acid (DNS) 2 assay or the Nelson-Somogyi method, whereas the other is based on the decreased staining value of blue starch-iodine complexes . The second method, which was developed by Fuwa and is widely used , is based on color development that results from iodine binding to starch polymers. However, the starch-iodine assays reported by diVerent researchers are quite diverse with iodine concentrations ranging from 3 M [12] to 0.25 mM and with the wavelength used to measure color development varying from 550 nm [15] to 700 nm . Moreover, -amylase activity is calculated as relative activity according to the following equation. Dextrinizing activity D (D 0 -D) ¥ D 0 £ 100 ¥ 10, where D is the absorbance of the enzyme sample and D 0 is the absorbance of the amylose control without the addition of enzyme . Dextrinizing activity calculated using this formula is therefore not expressed in units that are related to the amount of substrate consumed. In addition, since the assay has a Wnal volume of 20-200 ml, it is not suitable for screening a large number of samples. In this paper, we describe a microplate-based starch-iodine assay that measures the amount of starch degraded to determine the activity of -amylase and glucoamylase. We also propose a new strategy to distinguish between -amylase and glucoamylase enzymes by comparing the results obtained from the DNS and starch-iodine assays.
Foods
In vitro digestibility of starch is a common analysis in human nutrition research, and generally consists of performing the hydrolysis of starch by α-amylase in specific conditions. Similar in vitro assays are also used in other research fields, where different methods can be used. Overall, the in vitro hydrolysis of native starch is a bridge between all of these methods. In this literature review, we examine the use of amylolysis assays in recent publications investigating the complex starch structure-amylolysis relation. This review is divided in two parts: (1) a brief review of the factors influencing the hydrolysis of starch and (2) a systematic review of the experimental designs and methods used in publications for the period 2016–2020. The latter reports on starch materials, factors investigated, characterization of the starch hydrolysis kinetics and data analysis techniques. This review shows that the dominant research strategy favors the comparison between a few starch sampl...
Molecular weight characterization of starch and modified starches as tricarbanilate derivatives
Carbohydrate Polymers, 1986
Industrial corn starches modified with an oxidant, acid or enzyme have been analyzed by a high-performance size-exclusion chromatography (HPSEC) technique. The procedure involves derivatization of the starch to the corresponding tricarbanilate with separation afforded by commercially available polystyrene-divinylbenzene (PS-DVB) gel columns. Separation time was under 30 rain and UV detection at 235 nm allows the analysis of microgram quantities. The elution behavior of amylose and amylopectin tricarbanilates appears to depend on allowed conformational states. Amylopectin tricarbanilate (APTC) is hindered by branching and elutes much earlier than the exclusion limit of the column system according to linear polystyrene standards. Observation of an apparent hydrolysis resistant region of starch and the effects of the various hydrolytic treatments are discussed. Relative molecular weight data are presented utilizing the carbanilate of monodisperse pullulan polysaccharides as primary standards.