Cassava bagasse is generally disposed in the surrounding environment of the processing units. Starch is a polymer of glucose and contains amylose and amylopectin as building blocks. The hydrolysis of the starch present in cassava bagasse produces a broth with available reducing sugars, chiefly glucose, which could be directly fermented by microrganisms Bobbio and Bobbio, Due to richness in organic matter, basically starch, cassava bagasse could be in ideal substrate for biotechnological processes where the objective could be to produce metabolites with commercial value.
Cassava bagasse can be used directly in solid-state fermentation, or in submerged fermentation after hydrolysis. Table 1 shows the range of variation of its physico-chemical contents. Another approach to utilize cassava bagasse involves its hydrolyze to convert starch present in it into reducing sugars mainly glucose , and then uses it in submerged fermentation to produce metabolites. To obtain reducing sugars from cassava bagasse, it must have a thermal hydrolytic treatment with acid or enzyme.
The acid or enzymatic hydrolysis of cassava bagasse produces two fractions: one liquid composed of soluble sugars from the starch hydrolysis basically glucose , and one solid fraction composed of insoluble cellulose and fibers. The objective of this work was to compare the recovery of reducing sugars from cassava bagasse using two different hydrolysis methods, and also to compare the cost economics of both the methods of hydrolysis. The physical conditions for acid and enzymatic hydrolysis were optimized using an experimental factorial design, where the response variable was the reducing sugars concentration.
The response data were analyzed using the statistical program " Statistica " based on the response surface. Acid Hydrolysis: Acid hydrolysis was performed using hydrochloric acid at 0.
The tests were made in mL flasks, using 5 g of cassava bagasse and 50 mL of the acid solution. The enzymatic hydrolysis was performed in two steps. The optimal pH, reaction time, temperature and the enzyme concentration of both the steps were determined using the experimental factorial design. The tests were made in mL flasks, using 6 g of cassava bagasse, and 50 mL of water with the appropriate enzyme Carta, Reducing Sugar Analysis: The reducing sugars recovered from the cassava bagasse was analyzed by Somogyi-Nelson method Nelson, ; Somogyi, ; Somogyi, Energy Costs: The energy costs of both the processes, viz.
The hydrolysis costs were calculated considering the energy and the chemicals necessary for both the processes. Reactor: A cylindrical stainless steel reactor L with thermal insulation and jacket heated was used.
Its diameter was 1. Heat Needed for the Processes: In order to compare the heat necessary by both the methods of hydrolysis, the heat necessary to increase the temperature and the heat necessary to maintain it during each step of the both processes was calculated as described by Holman Heat to increase the temperature of the aqueous medium with cassava bagasse :.
The global coefficient of thermal exchange for the cylindrical wall was calculated using the following expression:. The first term was related to the convection inside the reactor.
To determine the medium parameters, water was considered. The global coefficient of thermal exchange for top and bottom flat walls was calculated using the following expression:. Total heat to maintain the temperature during the processes: The total heat necessary for the processes was calculated considering the time of each step of the process:. Table 2 shows the physico-chemical characteristics of the cassava bagasse used in this work, which has in general matching with those reported by Pandey et al.
Acid Hydrolysis: Figures 1 and 2 show the data obtained with cassava bagasse hydrolysis using acid. Highest reducing sugars value obtained was This value represented Considering the costs in energy, the most advantageous process to use for the hydrolysis of the residual starch present at the cassava bagasse was the acid one. The energy consumption for the enzymatic hydrolysis was While doing these comparisons, the equipment cost was not considered, as it was the same for both the processes.
Costs of the chemical components for the Acid and Enzyme Hydrolysis of cassava bagasse kg :. Considering the chemicals necessary for a batch, acid hydrolysis was much less expensive than the enzymatic one.
Cost of chemicals was considered as an important factor because the price difference was very high, which would largely affect any cost analysis. The only limitation with acid hydrolysis could be the issue of toxicity, because the acid process increases the medium salinity, and it could be a limiting factor.
Analysing the process yields of the recovered reducing sugars from the starch present in cassava bagasse, both processes were quite efficient and similar with Looking at the time required for each process, acid hydrolysis was more advantageous than the enzymatic process. For a batch, the acid hydrolysis was completed in only 10 minutes plus the time to heat and cool the material.
Quiz yourself on whether the following sugars are reducing sugars or non-reducing sugars. But if you want to go further down the rabbit hole, I invite you to read further to learn about…. One thing about all three tests is that the active reagent is not particularly bench stable and has to be freshly prepared.
The purpose behind using the tartrate is that it coordinates to the copper II and helps prevent it from crashing out of solution.
Once prepared, the substance to be analyzed is added, and the mixture is heated for a brief period. The ingredients are copper II sulphate, sodium carbonate note: hydroxide is also needed! Note: in the quantitative test, potassium thiocyanate is added, which results in a colourless white precipitate.
The first three lines below describe the procedure. Silver nitrate is converted to silver hydroxide, which forms silver I oxide, Ag 2 O. Then, addition of aqueous ammonia NH 3 results in formation of the silver-ammonia complex which is the active oxidant. The sample to be tested is then added to the freshly prepared active oxidant in a basic solution. A positive test results in a beautiful mirror of silver metal being precipitated out on the reaction vessel.
A variant of this procedure is used for the preparation of mirrors. Bottom line here is that adding base has the effect of increasing the concentration of the starting aldehyde. If I am wrong, please tell me leave a comment. One of the access points for the initiation of a single-electron transfer reaction is a carbon-metal bond, which can be achieved through base-promoted formation of an enolate.
That requires that the aldehyde have a proton on the alpha carbon i. Thus it would appear that the reaction needs to proceed through an enol. Hover here for a pop-up image or [ click for image of a hypothetical mechanism ].
Image sources: Benedicts solution. Tollens test. Note 1. The standard way to do it is the Pinnick oxidation. Note 2. The quantitative test apparently employs potassium isocyanate, which results in a colourless precipitate. See the mechanism section. Note 4. A very enjoyable post! In the 4th reaction, the charge is on the oxygen; this is preferable. What if a product contains high percentage of reducing sugar? What does it denotes?
I have prepared a product which contains Thank you very much for your posts they are very helpful. Blessings and thanks again! And thanks again for your very clear explanations. I have a question regarding reducing sugars as excipients with drugs. Some carbohydrates reducing sugars form covalent bonds with drugs that contain primary and secondary amines. So I have been looking at the Maillard reaction which breaks down the hydroxyl group of a reducing sugar and then forms Amadori products.
I have been searching for a reaction mechanism for the Amadori adduct formed from dexamphetamine and lactose. I was wondering if you could perhaps give a generic mechanism or a similar example. I note you give two examples of lactose and maltose as disaccharides that are reducing sugars as they contain the hemiacetal. I was wondering if you could give a general mechanism reacting with a primary amine such as R-NH2?. This website is phenomenal. Ashenhurst teaches these topics so much better than they do at school!
Keep up the great work! Your email address will not be published. Save my name, email, and website in this browser for the next time I comment.
Notify me via e-mail if anyone answers my comment. This site uses Akismet to reduce spam. Learn how your comment data is processed. Previous What is Mutarotation? A test for blood sugar suitable for diabetics should have a similar ease of use. So what does this have to do with sugars? A simple color change tells you if glucose is present! Hold on for a second. Et tu, fructose? Two main cases: mono and di-saccharides which lack a hemiacetal polysaccharides where the ratio of hemiacetals to acetal linkages is very low e.
Starch Sugars are able to form long chains with each other in arrangements known as polysaccharides. Test yourself. But if you want to go further down the rabbit hole, I invite you to read further to learn about… 8. This results in a carboxylic acid and red Cu I which precipitates out as copper I oxide.
The test is performed by adding the substance to be analyzed and heating briefly.
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