Date : 2011/04/28<br />Determination of Alcohol strength and Titrable acidity of an alcoholic beverage<br />Introduction:<br />Beer, alcoholic beverage made from cereal grains, usually barley, but also corn, rice, wheat, and oats. Beer is made using a process called fermentation, in which microscopic fungi called yeast consume sugars in the grain, converting them to alcohol and carbon dioxide gas. This chemical process typically produces beer with an alcohol content of 2 to 6 percent. Over 70 styles of beer are available today. Each style derives its unique characteristics from its ingredients and subtle differences in its brewing process.<br />Throughout history, wherever cereal grains were grown, humans made a beerlike beverage from them: they used wheat in Mesopotamia, barley in Egypt, millet and sorghum in other parts of Africa, rice in Asia, and corn in the Americas. Today, beer making is a major industry worldwide. <br />Acidity of alcohol beverage is expressed either in term of miliequivalents per litre or as acetic acid.<br /> <br /> NaOH + CH3COOH CH3COONa + H2O<br />Experiment 1: Determination of titrable acidity of an alcohol beverage<br />Materials: Chemicals:<br /><ul><li>Alcohol sampleDistilled water
Burettestand</li></ul>Procedure:<br /><ul><li>25 ml of the sample was pepetted.
Sample was titrated with 0.1 M NaOH using phenolphthalein as an indicator.</li></ul>Results <br />ReplicatesVolume oh NaOH (ml)112211.8<br />Calculations:<br />Mean value of NaOH volume =12+11.8 / 2=11.9 ml<br />NaOH moles=0.1 × 11.9 × 10 -3 =11.9 × 10 -4 mol<br />Acetic moles in 25 ml of the sample = 11.9 × 10 -4 mol<br />Acetic mass in 25 ml of the sample=11.9 × 10 -4 × 40<br /> = 476 × 10 -4 g<br />Percentage of acid = 476 × 10 -4 × 4<br />= 0.1904 g /100 ml<br />Experiment 2: Determination of alcohol strength using Ebulliometer<br />Materials:<br /><ul><li>Sample
Ebulliometer</li></ul>Procedure:<br />1) 15 ml of water was pour into the tank until the level of the interior ring fixed in fund to the inside boiler.<br />2) The arm was fixed with thermometer.<br />3) The water was filled to condenser to it’s maximum.<br />4) The spirit lamp was placed under the ring and wait until the water boils.<br />5) The mercury path was observed moving.<br />6) The zero mark of the scale was placed coincides to the mercury level and fix it.<br />7) The water was removed in the boiler and fill it with the sample.<br />8) Again the sample was boiled as earlier.<br />9) Mercury path moving was observed.<br />10) When it is stabilized the mark was slided along the scale and place where it coincides with the mercury level.<br />11)The value shown on the scale is the alcohol contenet of the sample.<br />Results <br />ReplicatesAlcohol strength %13.523.8<br /> Mean Alcohol strength % = 3.5 + 3.8 / 2 = 3.65 %<br />Discussion<br />A very important thing is, from experiment 1 we can measure titrable acidity only.Not the totale acidity of tha sample.alcohols are also acids.But result’s not including alcohol acidity.because alcohols don’t react with NaOH.<br />NaOH + Alcohols <br />The name ebulliometer has its roots in the latin word "ebullio" : meaning to boil or bubble up.<br />An ebulliometer is designed to accurately measure the boiling point (temperature) of water or a water solution, by measuring the temperature of the vapour generated away from the heat source .<br />An ebulliometer was first used to determine the molecular weights of substances, by measuring the changes in the boiling point of water cause by the presence of the unknown substance<br />An ebulliometer apparatus consists of -<br />1. - A chamber to hold the liquid whose boiling point is to be determined, designed to allow for a semi-remote heat source.<br />2. - A condenser (reflux), to continually condense the vapour generated, to maintain the initial concentration of the liquid being tested.<br />3. - A special, precision thermometer (Churchward), calibrated in 0.02oC with a range of 95 - 115oC<br />A special bent thermometer can also be used. The bend thermometer is able to accommodate a horizontal sliding scale with a zero pointer, allowing an approximate (+/- 0.1% v/v) alcohol concentration level to be read directly of the scale.<br />4. - A heat source such as a spirit (alcohol) burner.<br />5. A heat chimney/shield to promote efficient burning by drawing in oxygen via the convection currents created and to isolate the heat source from the vapour produced.<br />6. - An outlet tap to allow removal of rinsing or tested liquid.<br />Reeference <br /> wikipedia<br />17716502819400<br /> <br /> B.R.MADUSHAN<br />AS 65568<br />1ST YEAR<br />FOOD SCIENCE & TECHNOLOGY<br />