OLA - De La Salle University Manila College of Science...

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De La Salle University – Manila College of Science Environmental Chemistry – Lecture Partial Requirement for the Course Environmental Chemistry and a Term Paper about The Chemistry of Winemaking Submitted by: Aristotle John A. Yabut S25 Submitted to: Dr. Martin Ilao August 23, 2011 I.Introduction
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II. Winemaking, or vinification, is the production of wine, starting with selection of the grapes or other produce and ending with bottling the finished wine. Although most wine is made from grapes, it may also be made from other fruit or non-toxic plant material. Mead is a wine that is made with honey being the primary ingredient after water. Winemaking can be divided into two general categories: still wine production (without carbonation) and sparkling wine production (with carbonation). The science of wine and winemaking is known as oenology and the oldest known winemaking operation, estimated to be 8,000 years old, was discovered in Georgia. II. II. The Process of Winemaking 1 After the harvest, the grapes are taken into a winery and prepared for primary ferment. At this stage red wine making diverges from white wine making. Red wine is made from the must (pulp) of red or black grapes that undergo fermentation together with the grape skins. White wine is made by fermenting juice which is made by pressing crushed grapes to extract a juice; the skins are removed and play no further role. Occasionally white wine is made from red grapes, this is done by extracting their juice with minimal contact with the grapes' skins. Rosé wines are either made from red grapes where the juice is allowed to stay in contact with the dark skins long enough to pick up a pinkish color (blanc de noir) or by blending red wine and white wine. White and rosé wines extract little of the tannins contained in the skins. To start primary fermentation yeast is added to the must for red wine or juice for white wine. During this fermentation, which often takes between one and two weeks, the yeast 1 Jancis Robinson (2003). Jancis Robinson's WINE COURSE, A guide to the world of wine . BBC worldwide Ltd. . pp. 39.
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converts most of the sugars in the grape juice into ethanol (alcohol) and carbon dioxide. The carbon dioxide is lost to the atmosphere. After the primary fermentation of red grapes the free run wine is pumped off into tanks and the skins are pressed to extract the remaining juice and wine, the press wine blended with the free run wine at the wine maker's discretion. The wine is kept warm and the remaining sugars are converted into alcohol and carbon dioxide. The next process in the making of red wine is secondary fermentation. This is a bacterial fermentation which converts malic acid to lactic acid. This process decreases the acid in the wine and softens the taste of the wine. Red wine is sometimes transferred to oak barrels to mature for a period of weeks or months, this practice imparts oak aromas to the wine. The wine must be settled or clarified and adjustments made prior to filtration and bottling. The time from harvest to drinking can vary from a few months for Beaujolais nouveau
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OLA - De La Salle University Manila College of Science...

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