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Bread-Making Bread making depends on the activities of micro-organisms. The dry ingredients used in bread-making include flour, usually from wheat, salt, sugar, ascorbic acid and the yeast Saccharomyces cerevisiae. Water or milk is added to produce a thick, sticky dough which is folded repeatedly or kneaded. This dough is rested, folded again then shaped. The dough is left to "prove" in a humid atmosphere at approximately 35� Celsius. It is then reshaped and left to "prove" some more.During the "proving" process, fermentation of sugars in the dough, catalysed by enzymes from the yeast cells, produces carbon dioxide. The series of reactions that occur with the help of enzymes from yeast are: maltese from yeast a) Maltose in flour produces glucose invertase from yeast b) Sucrose from added sugar produces glucose + fructose zymase from yeast c) Glucose + fructose from previous reactions produce alcohol + carbon dioxide The production of carbon dioxide is needed to make the dough rise, or increase in volume. This process is called leavening. The overall effects of leavening are to make the dough lighter, more easily digested and with better flavour, enhanced by the production of organic acids, alcohols and esters by yeast cells. Baking evaporates off any alcohol and inactivates the yeast. ...read more.


As the pH of the milk changes, the structural nature of the proteins changes, leading to curd formation. Essentially, the proteins in the milk form a curd that entraps fat and water. Although acid alone is capable of causing coagulation, the most common method is enzyme coagulation. The physical properties of enzyme-coagulated milk are better than that coagulated purely with acid. The traditional source of enzyme is rennet. . After the coagulation sets the curd, the curd is cut. This step is usually accompanied with heating the curd. Cutting the curd allows whey to escape, while heating increases the rate at which the curd contracts and squeezes out the whey. The purpose of this stage of the process is to make a hard curd. Many surface ripened cheeses have their surfaces smeared with a bacterial broth. With others the bacteria is in the atmosphere of the curing chambers. These cheeses are called washed rind varieties as they must be washed regularly during their ripening period (longer than for Camembert or Brie) to prevent their interiors drying out. The washings also help promote an even bacterial growth across the surfaces of the cheeses. ...read more.


Wine-Making Grapes are firstly crushed. The crushed grapes and juice are called must. What happens next depends on the type of grape. Red-grape must is sent directly to the fermentation tanks. White-grape must is sent first to a wine press, where the juice is separated from the skins, because white wines are fermented from skinless grapes.The must, whether from red grapes or pressed white grapes, is ultimately sent to the fermentation tanks. These tanks are airtight. The tanks are cooled with glycol to maintain a temperature. The winemaker adds sugar and yeast to start the process of fermentation. The type of yeast and the amount of sugar added depends on the type of grape. Once the fermentation process is completed, red wines are sent to the press to separate the skins from the wine.. Once the yeasts are removed, the wines are stored in either stainless steel storage tanks or oak barrels. In some red wines, a second type of fermentation, called malolactic fermentation, is undertaken while in storage. In malolactic fermentation, the winemaker adds a bacteria to the wine that breaks down malic acid, a byproduct of aerobic (oxygen-requiring) metabolism, into lactic acid, a byproduct of anaerobic (no oxygen) metabolism. Lactic acid is a milder acid than malic acid. The aging process can be anywhere from three months to three years. . ...read more.

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