Glucose
In 1747, the German chemist Andreas Marggraf isolated a specific sugar from raisins. He moistened dried grapes with water to soften them before pressing out the juice. This process yielded a substance he described as a sort of sugar. The work appeared in the Histoire de l'académie royale des sciences et belles-lettres de Berlin on page 90. Another German chemist named Johann Tobias Lowitz discovered glucose in grapes in 1792. He distinguished this substance from cane sugar known as sucrose. Jean-Baptiste Dumas coined the term glucose in 1838. The name derived from the Ancient Greek word for sweet wine or must. Friedrich August Kekulé later proposed the term dextrose because aqueous solutions turn polarized light to the right. Hermann Emil Fischer received the Nobel Prize in Chemistry in 1902 for establishing the stereochemical configuration of sugars.
Glucose contains six carbon atoms and an aldehyde group making it an aldohexose. The molecule exists in both open-chain and cyclic forms within aqueous solutions. More than 99% of molecules form pyranose rings containing a six-membered heterocyclic system. A small proportion remains in the open-chain configuration at equilibrium. The ring closure creates two distinct products denoted alpha and beta. These isomers interconvert over hours through a process called mutarotation. Pure alpha-D-glucopyranose has a specific rotation angle of plus one hundred twelve point two degrees. Pure beta-D-glucopyranose measures plus seventeen point five degrees. The stable ratio reaches thirty-six percent alpha to sixty-four percent beta. The open-chain form acts as an essential component despite being barely detectable in solution.
Plants produce glucose through photosynthesis using sunlight water and carbon dioxide. All living organisms generate energy from the breakdown of monosaccharides via glycolysis. In humans about seventy grams of glucose circulate in the blood daily. Approximately four kilograms of glucose are produced in the liver every twenty-four hours. Neurons renal medulla cells and erythrocytes depend on glucose for their energy production. Glycolysis produces a net gain of two ATP molecules during anaerobic respiration. Aerobic respiration generates a maximum net production of thirty or thirty-two ATP molecules. Tumor cells consume above-average amounts of glucose leading to lactate formation even with oxygen present. This phenomenon known as the Warburg effect allows rapid tumor growth. Glucose concentrations in the brain usually range between four and six millimolar.
Glucose intravenous sugar solutions appear on the World Health Organization List of Essential Medicines. Blood sugar levels below forty milligrams per deciliter indicate hypoglycemia. Values over one hundred eighty milligrams per deciliter signify hyperglycemia. The 2-hour glucose tolerance test involves drinking a seventy-five gram glucose drink after fasting. Individuals with diabetes often carry small amounts of sugar in tablet form or hard candy. Fasting glucose tests measure levels after eight hours without food. The glycemic index measures speed of conversion to blood glucose relative to pure glucose. Artificial sweeteners do not lower blood sugar levels like natural sugars do. Confusion occurs when brain glucose drops below one millimolar while coma follows at lower levels.
Commercial glucose syrup has an annual worldwide production volume of twenty million tonnes. Enzymatic hydrolysis largely displaced acid-catalyzed reactions starting around 1982. Pullulanases from Aspergillus niger convert amylopectin to starch increasing yield significantly. Corn starch serves as the primary source in the United States almost exclusively. The reaction proceeds at pH values between four point six and five point two. Temperatures range from fifty-five to sixty degrees Celsius during processing. Mizuame represents the Japanese form made from sweet potato or rice starch. High-fructose corn syrup contains forty-two percent fructose in dry mass for most foods. Soft drinks in Mexico use cane sugar instead of high-fructose corn syrup mixtures. The process converts starch into glucose syrup containing more than ninety percent glucose.
Unbound glucose is a main ingredient found within honey. Selected plant foods contain varying amounts of free glucose per hundred grams. Apples hold about five point nine grams while dried figs contain nearly twenty-three grams. Grapes provide seven point two grams of free glucose per serving. Sweet potatoes offer one gram and red peppers contain only zero point one gram. Glucose acts as a sweetener humectant and creates softer mouthfeels in confectionery. Most soft drinks in the US utilize HFCS-55 with fifty-five percent fructose content. Caramelization occurs when heated under water-free conditions alongside amino acids. The Maillard reaction produces distinct flavors during cooking processes involving proteins. Various organic acids can be biotechnologically produced from glucose through fermentation methods.
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Common questions
Who discovered glucose and when was it first isolated?
Andreas Marggraf isolated a specific sugar from raisins in 1747. Johann Tobias Lowitz later discovered glucose in grapes in 1792.
What is the chemical structure of glucose molecules?
Glucose contains six carbon atoms and an aldehyde group making it an aldohexose. More than 99% of molecules form pyranose rings containing a six-membered heterocyclic system.
How much glucose circulates in human blood daily?
In humans about seventy grams of glucose circulate in the blood daily. Approximately four kilograms of glucose are produced in the liver every twenty-four hours.
When did Jean-Baptiste Dumas coin the term glucose?
Jean-Baptiste Dumas coined the term glucose in 1838. The name derived from the Ancient Greek word for sweet wine or must.
Which foods contain free glucose per hundred grams?
Apples hold about five point nine grams while dried figs contain nearly twenty-three grams. Grapes provide seven point two grams of free glucose per serving.