[biofuel] Fermentable grains

[DAVID REID]

Skaar,           As Geoff has pointed out they need to be broken down to simple sugars Yeast while they can even take in and absorb more complex sugars like dextrose (a dimer or two molecule sugar) in order to utilize sugars need these available in the form of glucose. With the process of photosynthesis plants produce glucose units which are then linked together to form more complex sugars like detrose, dextrins (many dextrose units linked together), sucrose, fructose, cellulose, etc etc. Fermentation is normally done by acid  or enzymatic hydrolysis action  where the molecule normally takes the hydrogen atom from water (H2O)to make ethanol, and oxygen is combined with  carbon atoms(CO2). Most grains are no longer simple mono sugars but lots of more complex sugars) starch in the form of amylose and amylopectin locked up in chains which need to be broken down first in order to be used. Only those plants that produce fruits where the sugars are generally left as simple sugars due to rapid ripening  and growth as an attractant to animals and insects are generally fermentable without treatment (fruit itself or its juice). Those plants that grow and form slowly generally have their sugars in more complex form generally locked in place by such things as pectins lignans and cellulose. To make it easier to understand please find enclosed a Simple Sugar Primer I wrote a few months ago.. Tony you have my permission to put this on the site if you want. I believe it is already on Tonys site somewhere. B.r.,  David     Sugar Primer as follows: Sugar molecules are formed from carbon, hydrogen, and oxygen by the process known as photosynthesis. Yeasts convert sugar molecules into alcohol and carbon dioxide (CO2) by means of a simple enzymatic action. There are many forms of sugar and the name the whole family is known under is saccharide. Under certain conditions sugar molecules have an attraction for one another and 2 small molecules combine and form a bigger molecule. Sometimes these molecules combine and then sometimes combine again etc creating complex saccharide molecules or chains. Small simple sugars are called monosaccharides, when 2 simple sugars combine they are called disaccharides, and when 3 or more combine they are called polysaccharides. Large polysaccharide molecules consist of thousands of small monosaccharide molecules and pectin, gums, and cellulose are examples of these. Monosaccharides are simple sugars and there are many different kinds with each sugar molecule containing 3, 4, 5, or 6 carbon atoms with each being named  after these number of carbon atoms eg. pentose = 5, hexose = 6. The two main sugars we are concerned with namely glucose and fructose are hexose monosaccharides. Glucose is the sugar that provides the sugar for the human body. Fructose as well as being a component of sucrose is found in many different kinds of fruit and is the principle one in honey. Fructose is also sometimes known as levulose. Glucose is the main common simple sugar  and is a part of many different disaccharides and polysaccharides eg. corn starch (most common source). Disaccharides are composed of 2 simple sugars combined together which can either be similar or dissimilar sugars eg. Maltose = 2 glucose molecules (dimer or double molecule of glucose), sugar or sucrose = 1 glucose + 1 fructose molecule. Normally disaccharide sugars must be hydrolyzed and split into their simple sugar components before they can be fermented. In the case of  sucrose (sugar) they are split into equal numbers of glucose and fructose molecules. Glucose has a Relative Sweetness level of 70 while fructose has double that level at 140. By switching a certain amount of  glucose for sucrose it can be seen that it is relatively easy to adjust the Relative Sweetness level before one starts fermentation.  Disaccharides are produced commercially by the incomplete hydrolysis of larger more complex polysaccharides ie. the hydrolysis process is halted prematurely rather than being taken to the final stage of being further split into glucose and the other components sugar/s. It can also be produced by combining 2 monosaccharide sugars by means of a condensation reaction to form disaccharide sugars. Microorganisms such as yeast produce enzymes that hydrolyze sucrose. Lactose is another disaccharide (milk sugar) and is only found in milk from mammals. It is made up of 1 glucose sugar and 1 galactose sugar molecule. In the case of NZ and Australia it is the major source of commercially available spirits. It is easily hydrolyzed and has practically no sweet taste having a Relative Sweetness of 40. It is therefore very easy to combine with most spirit bases without changing the profile. To hydrolyse lactose you need the enzyme lactase which allows the feedstock to then be fermented by the common Saccharomyces cerevisiae yeasts. A principal source of lactase is the yeast Kluyveromyces fragilis which is more commonly used to ferment lactose directly to ethanol. Polysaccharides are large complex molecules containing 3 or more monosaccharides (and in some cases number more than several thousand simple sugar molecules) which are used by living organisms to store energy. They also form part of cell structural fibres. Starch consists of many glucose monosaccharides hooked together in both linear  and branched forms. Pectin, gums, and cellulose  are some of the other main polysaccharide molecules. Unfortunately cellulose  is normally only fermented by xylose fermenting yeasts or bacteria so at least 30% of any plant materialis is generally always unfermentable. For polysaccharides to be fermentable they need to be split or broken down (hydrolyzed) again into simple sugars. This can be acheived by enzymes, acids, or heat. Quite often the process is a joint one combining two or all three of these. The main enzymes used or part of alcohol fermentation are Alpha amylase, Beta amylase, Glucamylase (Amylogglucosidase), all of which are used to break down amylose (major component of starch) and amylopectrin (other major component of starch which is less easily hydrolyzed due to its large branched chains nature of construction). In addition other enzymes that are used are Beta glucanase, Lactase (milk sugar enzyme), Maltase, and Protease. Zymase is the complex of enzymes produced by yeasts which are responsibler for the fermantation of sugars to ethanol. Acids that are involved or used in fermentation are Tartaric, Malic (wine), Succinic, Lactic, Citric, Proprionic, Sulpheric, and Hydrochloric.     At this stage this covers the basics. All in the meantime. B.r.,  David  eGroups Sponsor Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html To unsubscribe, send an email to: [EMAIL PROTECTED]