Making+Sugars+with+Enzymes

//1. What are some of the advantages and disadvantages of this way (use of boiling acids) of making sugar from starch, compared to using cane sugar?// //Advantages:// During the Napoleonic Wars, imports of cane sugar (sucrose) from the West Indies were impossible, and not enough sucrose could be produced in Europe by growing sugar beet. Therefore, the re was a significant decrease in the accessibility to cane sugar. This problem could be solved by making sugar from starch because starch was easily accessible and available in abundance. Each molecule of starch is made up of hundreds of molecules of the sugar glucose all joined together in branching chains. Although starch is neither sweet nor soluble, glucose is sweet and soluble. This method of making sugar from starch fully utilizes the starch and puts it to good use.

//Disadvantages:// The reactor vessels in which the process takes place have to withstand concentrated acids at temperatures of 150 degree celsius. This temperature has to be maintained for several hours, and the final product is often discoloured by the heat and the acid. Hydrolysis is the decomposition of a chemical compound by reaction with water, such as the dissociation of a dissolved salt or the catalytic conversion of starch to glucose. Water is required for hydrolysis to take place. When boiling acids are used to make glucose from starch, the reactor vessels in which the process takes place have to withstand concentrated acids at temperatures of 150 degree celsius. This temperature has to be maintained for several hours, and the final product is often discoloured by the heat and the acid. This is not the case when enzymes are used to make glucose from starch. The advantages of using enzymes would be that enzyme action does not require high temperatures to take place and carry out the fastest at 39 degree celsius, which is the optimum temperature. Also enzymes being biological catalysts, they help to speed up the rate of reaction and it does not require as much time as using boiling acids.
 * 1) //What is hydrolysis?//
 * 1) //What are the advantages of using enzymes to make glucose from starch, compared to using boiling acid?//
 * 1) //Why would Aspergillus secrete amylase externally in nature?//

The Aspergillus feeds on nutrients that are found externally in nature, instead of ingesting it first like most organisms. It digests nutrients externally and secretes amylase externally so that starch can be digested outside its body before ingesting it. Sugars are rarely added to foods for their nutritional value (their energy content). Instead, they are added to give a ‘gooey’ texture, or a sweet taste. Therefore, should a sugar that was twice as sweet be used, then the total amount of sugar required to make the substance sweet would be lesser in amount (a lesser amount of sugar would be sufficient to make the substance equally sweet). This will help the food manufacturer have to manufacture less sugar for the same price and he will be able to earn a profit. An increase in the enzyme concentration increases the reaction rate.
 * 1) //If you were a food manufacturer, why would you want to replace glucose with a sugar that was twice as sweet?//
 * 1) //What factors affect how well an enzyme works?//

An increase in the substrate concentration increases reaction rate to a point. Reaction rate does not continue increasing but levels off as the amount of substrate continues to increase. The reaction rate changes because after a certain substrate level the enzymes are fully saturated by substrate and the rate cannot increase anymore.

An optimum temperature for an enzyme is the temperature at which enzyme activity is maximum. Most enzymes perform poorly at low temperatures because chemical reactions occur slowly or not at all at low temperatures (enzyme activity will reappear when the temperature increases; usually enzymes are not damaged by moderately low temperatures. As the temperature increases, so does enzyme activity, until the point is reached where the temperature is high enough to damage the enzyme’s structure. At this point, the enzyme ceases to function; a phenomenon called enzyme or protein denaturation. Therefore, enzyme action takes place the fastest at body temperatures of organisms, such as 37 degree celsius.

Like all proteins, enzymes are denatured by extremes of pH (very acidic or alkaline). Within these extremes, most enzymes are still influenced by pH. The optimum pH for pepsin is 1-2, for trypsin is approximately 7.5-8.2 and for urease is approximately 6.5-7.0. The temperature and pH levels of the environment inside the bioreactor will have to constantly measured and controlled to ensure that they are at the optimum levels for the enzyme activity to take place at the maximum. Enzyme and substrate concentration inside the bioreactor should also be monitored. The enzyme itself remains unchanged throughout the catalyzing process or chemical reaction; its presence merely allows the reaction to take place more rapidly. Therefore, they can be “reused as many times as possible”. The enzymes are “stuck” in the glycoproteins and glycolipids of the plasma membrane as these structures act as surface receptors for the cell. Starch --> Each molecule of starch is made up of hundreds of molecules of the sugar glucose all chemically bonded together in branching chains --> Boiling with concentrated acid breaks up the giant, insoluble and unsweet starch molecule into sweet, soluble glucose molecules --> Enzymes such as amylase work in bioreactors with controlled optimum conditions --> Enzyme molecules are trapped inside the bioreactors so that they can be reused and are stuck to the supporting material --> Enzyme immobilization --> Glucose produced --> Enzymes such as glucose isomerase bring about the rearrangement of atoms in the glucose molecule --> Enzyme reacts with the glucose molecules drifting past, converting them to fructose molecules --> Fructose formed Enzymes are used by the pulp and paper industry for the removal of “stickies”, the glues, adhesives and coatings that are introduced to pulp during recycling of paper. Stickies are tacky, hydrophobic, pliable organic materials that not only reduce the quality of the final paper product, but can clog the paper mill machinery and cost hours of downtime. Chemcial methods for removal of stickies have, historically, not been 100% satisfactory. Stickies are held together by ester bonds, and the use of esterase enzymes in pulp has vastly improved their removal. Esterases cut the stickies into smaller, more water soluble compounds, facilitating their removal from the pulp. Since the early half of this decade, esterases have become a common approach to stickies control. Their limitations are, being enzymes, they are typically only effective at moderate temperature and pH. Also, certain esterases might only be effective against certain types of esters and the presence of other chemicals in the pulp can inhibit their activity. The search is on for new enzymes, and genetic modifications of existing enzymes, to broaden their effective temperature and pH ranges, and substrate capabilities. Enzymes have been used in many kinds of detergents for over 30 years, since they were first introduced by Novozymes. Traditional use of enzymes in laundry detergents involved those that degrade proteins causing stains, such as those found in grass stains, red wine and soil. Lipases are another useful class of enzymes that can be used to dissolve fat stains and clean grease traps or other fat-based cleaning applications. Currently, a popular area of research is the investigation of enzymes that can tolerate, or even have higher activities, in hot and cold temperatures. The search for thermotolerant and cryotolerant enzymes has spanned the globe. These enzymes are especially desirable for improving laundry processes in hot water cycles and/or at low temperatures for washing colors and darks. They are also useful for industrial processes where high temperatures are required, or for bioremediation under harsh conditions (eg. in the arctic). Recombinant enzymes (engineered proteins) are being sought using different DNA technologies such as site-directed mutagenesis and DNA shuffling.
 * 1) //Which conditions inside the bioreactor will have to be constantly measured and controlled?//
 * 1) //Why is it possible that the enzymes can be “reused as many times as possible”?//
 * 1) //From your knowledge of plasma membrane, describe where would the enzymes be “stuck” in.//
 * 1) //Try to summarise the whole process of converting starch to glucose and fructose as a flow diagram.//
 * 1) //Name a few other uses that you can find in your home or in local industry.//