Chemistry of alcoholic beverages

LECTURE 4
CHEMISTRY OF ALCOHOLIC BEVERAGES.
Plan:

1. 
   Chemistry of alcohol. The composition of raw materials for the production of alcohol. Chemical changes in the production of alcohol.
   
2. 
   Fermentation process. The conversion of polysaccharides into soluble sugars. The formation of higher alcohols during fermentation.
   
3. 
   Increased volatile acidity. Chemical changes during storage of wine.
   
4. 
   Secondary fermentation. Composition of raw materials for beer and soft drinks. Hops and malt. Mash preparation processes.
   
5. 
   Protein-maltose pause. Preparation of beer wort. Substances that pass from hops to beer.
   

Keys and phrases: Liquor from Wine, Fruit, Cereals and Sugar Cane, alcoholic fermentation, Beer and wine, Cereal grains
Sources: https://www.youtube.com/watch?v=B1xNSJ1bHPk

Alcoholic beverages are produced from sugar containing liquids by alcoholic fermentation. Sugars, fermentable by yeasts, are either present as such or are generated from the raw material by processing, by hydrolytic cleavage of starches and dextrins, yielding simple sugars. The most important alcoholic beverages are beer, wine and brandy. Beer and wine were known to early civilizations and were produced by a well-developed industry. The distillation process for liquor production was introduced much later. The nutritional energy value of ethanol is high (29 kJ/g or 7 kcal/g).

Beer making or brewing involves the use of germinated barley (malt), hops, yeast and water. In addition to malt from barley, other starch- and/or sugar-containing raw materials have a role, e. g., other kinds of malt such as wheat, unmalted cereals called adjuncts (barley, wheat, corn, rice), starch flour, starch degradation products and fermentable sugars. The use of additional raw materials may necessitate in part the use of microbial enzyme preparations.
Cereal grains contain starch and protein as the major components and lipid, non-starch carbohydrates, phytic acid, vitamins, and minerals as the minor components. Physical interactions and chemical reactions occur between these constituents during the processing and storage of cereal products, which determine their quality, storage stability, and nutritional value. With an increasing population of people suffering from celiac disease, diabetes, obesity, and other metabolic syndrome, there are opportunities and challenges for the food industry to develop healthier cereal products through utilizing novel ingredients and improving processing technologies. This book chapter offers a good review of chemical compositions of different cereal grains, processing technologies applied to produce various cereal foods, and future trends of research and product development in this area.
Wheat protein content is an important consideration for all end products (uses of wheat) from bread baking to noodles, paste, cakes, and biscuits. Wheat protein content varies widely depending on wheat class, growing region, type and quality of soil, and of course fertilizers input (amount and timing), nitrogen in particular. All other factors being equal, flour from higher protein wheat has greater water absorbing capacity and thus greater bread volume potential, depending somewhat on the baking process used. Wheat protein content is strongly correlated to wet gluten content and both are used as quality indicators when wheat price is being negotiated between sellers and buyers. While protein content is an intrinsic genetic trait and therefore a selection criterion in breeding programs, environmental impact is by considerably greater than that controlled by the breeders. Wheat and flour quality, however, is further complicated with protein quality, processing, and the relationship of protein and starch specifically in various food systems. Some of these aspects will be discussed later.