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Fermented products are:. Fermented products are those whose production involves the action of microorganisms or enzymes which cause desirable biochemical changes and significant modification to the food. Origins of Some Fermented Products. Fermentation processes:. Lactic acid Alcoholic
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Fermented products are: Fermented products are those whose production involves the action of microorganisms or enzymes which cause desirable biochemical changes and significant modification to the food.
Fermentation processes: • Lactic acid • Alcoholic • Acetic acid • Propionic acid
Fermented foods • Beverages • Dairy products • Cereals • Meat and fish • Fruits and vegetables
Beverages Beer Wine Sake Cider spirits
Dairy products Cheese Yoghurt Kefir Kurut -dry yoghurt ball Kumis – alcoholic beverage from mari’s milk
Cereals Breads Rolls Dosa (fermented crepemade from fermented rice and black lentils), idli (cakes 2-3 inches in diameter made by steaming a batter consisting of fermented rice and black lentils), adai (dosa); lao-chao (rice) , kenkey (sourdough dumpling made or corn such as sadza or ugali), ogi (fermented cereal porridge) Injera (flat pancakes made of iron rich teff (grass specie) flour)
Meat and Fish Jerky, country ham, salami, pepperoni pickled meat Fish sauce, bagoong (mixture fish and brine, traditionally left to ferment for 10 to 12 months until it produces bubbles and acquires its characteristic pungent odor.
Fruits & vegetables Pickled fruits & vegetables Olives Sauerkraut
Contribution of the fermented foods: • Enrichment of the human diet • Preservation of substantial amounts of food • Enrichment of nutritional value of food (vitamins, proteins, essential amino acids etc] • Detoxification of food (flatulence-causing sugars, lectins, phytates etc] • Decrease the cooking time and fuel requirements
Preservation principle: To hinder (delay) the growth of food spoilage microorganisms
Alcoholic fermentation: Simple sugars yeasts > ethanol Saccharomyces cerevisiae
Major Reaction: Glucose to Carbon Dioxide and Ethanol Special flavors and aromas of beers arise from minor biochemical reactions
Yeast Saccharomyces sp.
Yeasts involve in fermentation should possess: • Rapid and relevant carbohydrate fermentation ability; • Appropriate flocculation and sedimentation characteristics; • Genetic stability; • Osmotolerance
Yeasts involve in fermentation should possess: • Ethanol tolerance • Ability to produce elevated concentration of ethanol; • High cell viability for recycling; • Temperature tolerance.
Alcoholic fermentation is affected by: • Oxygen supply • Sugar content • Alcohol content • Temperature
Alcoholic fermentation: • Unlimited oxygen supply - cell growth • Limited oxygen supply - alcohol production
Beer A diluted solution of ethanol with a characteristic flavour arising from the use of malt as predominant source of carbohydrates and other yeast nutrients and hops as a source of bitter components.
Kinds of beer • Lager - produced by bottom fermen- ting yeasts ( Saccharomyces uvarum) . • Ale - produced by top fermenting yeasts ( Saccharomyces cerevisiae)
Production of beer: • Malting • Mashing • Boiling of wort with hops • Fermentation • Storage
Malt • Made from barley that has been allowed to germinate. • Germination produces enzymes that during mashing converts starch into simpler sugars and proteins into peptides. • This malt is then used by the yeast in the fermentation process. • Before mashing the malt may be roasted to darken the color and harden a beer. barley
Malting (preparation of malt): • Soaking barley grains in water at 10-15 0C • Germination of barley grains at 16-21 0C for 5-7 days • Separation germs and sprouts • Crushing the malt
Mashing (preparation of wort) • Mixing malt with water at 38-50 0C (protein hydrolysis) • Saccharafication of malt at 65-70 0C (hydrolysis of starches to simple sugars) • Inactivation of enzymes at 75 0C • Separation of insoluble materials.
Wort • Brewers' wort commonly has 8-14% total solids. • 90-92% are carbohydrates: glucose, fructose, maltose, sucrose, maltotriose. • Nitrogenous compounds, such as, amino acids. • Vitamins: biotin, inositol, pantothenic acid, pyridoxine, and thiamine are present in wort and utilized by Brewers' yeast. • Phosphates, chlorides, sulfates and other anions are present with the cations Na, K, Ca, Mg, Fe, Cu, and Zn.
HOPS Hops are the flowering portion of the hop vine. These flowers not only fight off bacterial infections in the beer, they aid in clarification of the beer, stabilize the flavor, help retain head, and aid in ones ability to drink the beer. Hop oils are produced in the Lupulin glands of the flower. These oils are non-polar, and can only be extracted through a short boiling and contribute to the bitterness of a beer.
Boiling of wort with hops is done to: • concentrate it • sterilize it • inactivate enzymes • extract soluble substances from hops • coagulate and precipitate proteins • contribute antiseptic resins: humulone, cohumulone, adhumulone.
Fermentation of beer • Pitching (inoculation)- 1lbs of yeasts per barrel of wort • Lager beer is fermented at 7-15 0C • Ale beer is fermented at 18-22 0C • Fermentation - 9 days • At the end of fermentation yeasts are skimmed (top-fermenting) or are cropped (bottom-fermenting).
Fermentation of Ales • Top fermenting-rise to the surface. • Warmer temps- 60-70F • More rapid growth • Create more esters • Complex and Fruity • Ales, porters, stouts, and wheat beers.
Fermentation of Lager • Bottom fermenting-yeast settle to the bottom of the fermenter as fermentation reaches completion. • Colder tempeatures: 47-58F • Slower growth • Crisp and hoppy like a pilsner or sweet and malty like a Dopplebock. • Examples: Pilsners, Bocks, and American malt liquors.
Storage and packaging • after fermentation beer is stored (lagered) at 0 C (several weeks to several months) to remove the “green” flavors caused by diacetyl and acetaldehyde which can impact the taste adversely as humans can taste them at very low concentrations • clarified or filtered • pasteurized at 60 C shortly • carbonated to CO2 content 0.45-0.52% • packaged to cans or bottles.
Beer defects (off flavour) may be due to: • butyric (Clostridium sp.) or lactic acid fermentation during mashing process. • Inoculum contaminated with wild yeasts or lactic acid bacteria. - Yeasts may produce off flavor. -Bacteria may produce sour taste and/or silky turbitidy.
WINES Products obtained by alcoholic fermentation of grapes, grape juices, fruit juices, berries, rhubarb, honey etc by yeasts.
Wine –definition of terms • Vintage – year grapes are grown and harvested. • Dry – wine with no sugar after fermentation • Sweet – wine with small amount of sugar left over • Body – the weight of wine • Style – overall impression of wine • Bouquet – a wine scent that comes from wine making process • Aromatic – components of wine scent that comes from grape itself
Wine – Basic types Five basic types of wine are: • Red Wine • White Wine • Rose Wine • Sparkling Wine - carbonated • Fortified Wine - high alcohol content • Sherry - Spanish style wine (amber to brown) can be made sweet or not sweet. • Port - Sweet red wine originally from Portugal • Madeira - from Madeira Islands made from cooked grapes & aged • Marsala - Italian wine made from concentrated grape juice.
Kinds of wines • still wines • sparkling wines • artificially carbonated wines
Kinds of wines • Dry vs. sweet wines • Unfortified vs. fortified wines • Red vs. white wines • Grape vs. fruit wines • Table vs. dessert wines
How wine is made • Harvesting --- Sugar/Acid Ratio • Pressing Techniques -- Red, White or Rose? • Fermentation • Maturing • To bottle
Grape used for production of wine • Varies in grape species and cultivars • Vitisvinifera, V. labrusca • Cabernet Sauvignon, Chardonnay, Gamay, Mission, etc. refer to different varieties or cultivars of the Vitisvinifera Cabernet SauvignonChardonnayGamay Mission • Different in compositions (sugar contents, pigmentation, etc.) • Different climates and soil preference • Wine quality varies greatly • Climate factors have important effect on grape quality and maturity
Grape Composition • Water 70-85% of the juice volume • About 20% sugar • Simple sugars largest constituent of grapes or must • Important for S. cerevisiae to produce ethanol • Glucose (~50%), Fructose (~50%, increase in over-ripened grapes), sucrose (<1%, in V. labrusca up to 10%) • Other sugars very low conc. • Sugar content in final product • “dry”: 0.1%-0.2% • “sweet” >10g/L • “very sweet” as much as 100g/L-200g/L
Organic Acids • Second in content constituent in must • Very important in wine quality • Provide low and well buffered pH (3.0-3.5) • Antimicrobial activities • Stabilizes anthocyanins (color, antioxidant, desirable flavor) • Volatile acids (acetic acid and others) very low • Fixed acids (malic acid and tartaric acid ~5:1) important to maintain the right acidity of wine and anti-spoilage, affected by environmental factors
Nitrogenous Compounds • Total N content in must range from 0.2g/L to 0.4g/L • Generally adequate for rapid growth of yeast • Biogenic amines (histamine and tyramine) in wine (by wine bacteria) can cause adverse reactions • Ethyl carbamate potential carcinogen, concentration increased by heat treatment and high urea concentration.
Polyphenols • Polyphenolic compounds naturally occurring in grapes, some are introduced later • Contribute to color, flavor, aroma, mouth feel to the wine
Production of wine After harvesting: • The grapes are transported to the winery where they undergo destemming and crushing. • There are a variety of presses that are used to produce the juice, which is called “must”. • The sugar in the wine is used by the yeast to produce ethyl alcohol and carbon dioxide gas, thus making wine. • The type of yeast can affect the qualities of the wine as will other compounds in the wine - some naturally occurring and some that are byproducts of the winemaking process. Small Bladder Press Crusher Large Rotary Press
Steps involve in fermentation of wine: • Preparation of must (grape juice, crushed grapes, fruit juice]. • inoculation of must with wine yeasts (2-5% ]. • aeration of must to encourage the growth of yeasts and to facilitate the extraction of pigments from a skin (mixing must twice a day ].
Steps involve in fermentation of wine: • Active fermentation: - red wines 24 -27 0C; 3-5 days; - white wines 10-21 0C; 7-14 days; • separation of fermented juice from residue (pomace); • placing fermented juice under light CO2 pressure • secondary fermentation: 21-29 0C, 7-11 days. • aging of wines.
Differences in making red and white wine • White Wine: • Grapes for white wine are harvested and pressed. • The must is fermented in stainless steel tanks. • Some white wines, such as Chardonnay, is aged in oak barrels. • The wine is bottled • Most white wines are not bottle aged but consumed with in 3 years of bottling. • However, an exception is particularly fine wines made from Chardonnay and Champagne. • Red Wine: • Grapes for red wine are harvested, crushed. • The must is left with the skins during fermentation to produce the red color. • Red wine is commonly aged in oak barrels for 6 to 24 months. • The wine is bottled. • Many red wines are ready to drink after bottling. • However, some red wines, such as Cabernet Sauvignon, will benefit with some bottle age.