Food and Food and industrial industrial

microbiologymicrobiology

Khairul Farihan KasimKhairul Farihan Kasim

CO3: CO3:

Ability to define, describe and Ability to define, describe and utilize microbial growth in utilize microbial growth in fermentation and biological fermentation and biological process process

At the end of the chapter, the At the end of the chapter, the student should be able to:student should be able to:

discuss the interaction of intrinsic (food-related) and extrinsic (environmental) factors discuss the interaction of intrinsic (food-related) and extrinsic (environmental) factors related to food spoilagerelated to food spoilage

describe the various physical, chemical, and biological processes used to preserve describe the various physical, chemical, and biological processes used to preserve foodsfoods

discuss the various diseases that can be transmitted to humans by foodsdiscuss the various diseases that can be transmitted to humans by foods

differentiate between food infections and food intoxicationsdifferentiate between food infections and food intoxications

discuss the detection of disease-causing organisms in foodsdiscuss the detection of disease-causing organisms in foods

describe the fermentation of dairy products, grains, meats, fruits, and vegetablesdescribe the fermentation of dairy products, grains, meats, fruits, and vegetables

discuss the toxins produced by fungi growing in moist corn and grain productsdiscuss the toxins produced by fungi growing in moist corn and grain products

discuss the direct use of microbial cells as food by humans and animalsdiscuss the direct use of microbial cells as food by humans and animals

list foods that are made with the aid of microorganisms and indicate the types of list foods that are made with the aid of microorganisms and indicate the types of microorganisms used in their productionmicroorganisms used in their production

describe probioticsdescribe probiotics

discuss the sources of microorganisms for use in industrial discuss the sources of microorganisms for use in industrial microbiology and biotechnologymicrobiology and biotechnology

discuss the preservation of microorganismsdiscuss the preservation of microorganisms

describe the design or manipulation of environments in which describe the design or manipulation of environments in which desired processes will be carried outdesired processes will be carried out

discuss the management of growth characteristics to produce the discuss the management of growth characteristics to produce the desired productdesired product

list the major products or uses of industrial microbiology and list the major products or uses of industrial microbiology and biotechnologybiotechnology

discuss the use of microorganisms in manufacturing biosensors, discuss the use of microorganisms in manufacturing biosensors, microarrays, and biopesticides microarrays, and biopesticides

discuss the manipulation of microorganisms in the environment to discuss the manipulation of microorganisms in the environment to control biodegradation control biodegradation

Microorganism Growth in Microorganism Growth in Foods Foods

Intrinsic and Extrinsic FactorsIntrinsic and Extrinsic Factors

Intrinsic FactorsIntrinsic Factors

compositioncompositionpHpHpresence and availability of waterpresence and availability of wateroxidation-reduction potentialoxidation-reduction potential

altered by cookingaltered by cookingphysical structurephysical structurepresence of antimicrobial substancespresence of antimicrobial substances

Food compositionFood composition

Carbohydrates–do not result in major Carbohydrates–do not result in major odorodor

Proteins and/or fats result in a variety of Proteins and/or fats result in a variety of foul odors (e.g., putrefactions)foul odors (e.g., putrefactions)

pHpHlow pH allows yeasts and molds to low pH allows yeasts and molds to

become dominant; higher pH allows become dominant; higher pH allows bacteria to become dominant; higher pH bacteria to become dominant; higher pH favors putrefaction (the anaerobic favors putrefaction (the anaerobic breakdown of proteins that releases breakdown of proteins that releases foul-smelling amine compounds)foul-smelling amine compounds)

Physical structure affects the course Physical structure affects the course and extent of spoilageand extent of spoilage

Grinding and mixing (e.g., sausage and Grinding and mixing (e.g., sausage and hamburger) increases surface area, hamburger) increases surface area, alters cellular structure, and distributes alters cellular structure, and distributes microorganisms throughout the foodmicroorganisms throughout the food

Vegetables and fruits have outer skins Vegetables and fruits have outer skins that protect against spoilage; spoilage that protect against spoilage; spoilage microorganisms have enzymes that microorganisms have enzymes that weaken and penetrate such protective weaken and penetrate such protective coveringscoverings

Presence and availability of waterPresence and availability of water

Drying (removal of water) controls or Drying (removal of water) controls or eliminates food spoilageeliminates food spoilage

Addition of salt or sugar decreases water Addition of salt or sugar decreases water availability and reduces microbial spoilageavailability and reduces microbial spoilage

Even under these conditions spoilage can Even under these conditions spoilage can occur by certain kinds of microorganismsoccur by certain kinds of microorganisms

Osmophilic–prefer high osmotic pressureOsmophilic–prefer high osmotic pressureXerophilic–prefer low water availability Xerophilic–prefer low water availability

Oxidation-reduction potential can be affected Oxidation-reduction potential can be affected (lowered) by cooking, making foods more (lowered) by cooking, making foods more susceptible to anaerobic spoilagesusceptible to anaerobic spoilage

Many foods contain natural Many foods contain natural antimicrobial substances antimicrobial substances coumarins – fruits and vegetablescoumarins – fruits and vegetableslysozyme – cow’s milk and eggslysozyme – cow’s milk and eggsaldehydic and phenolic compounds – aldehydic and phenolic compounds –

herbs and spicesherbs and spicesallicin – garlicallicin – garlicpolyphenols – green and black teaspolyphenols – green and black teas

Extrinsic FactorsExtrinsic Factors

temperaturetemperaturelower temperatures retard microbial lower temperatures retard microbial

growthgrowthrelative humidityrelative humidity

higher levels promote microbial growthhigher levels promote microbial growthatmosphereatmosphere

oxygen promotes growthoxygen promotes growthmodified atmosphere packaging (MAP)modified atmosphere packaging (MAP)

use of shrink wrap and vacuum use of shrink wrap and vacuum technologies to package food in controlled technologies to package food in controlled atmospheresatmospheres

Temperature and relative humidity–at higher Temperature and relative humidity–at higher relative humidity, microbial growth is initiated relative humidity, microbial growth is initiated more rapidly, even at lower temperaturesmore rapidly, even at lower temperatures

Atmosphere–oxygen usually promotes growth and Atmosphere–oxygen usually promotes growth and spoilage even in shrink-wrapped foods since spoilage even in shrink-wrapped foods since oxygen can diffuse through the plastic; high CO2 oxygen can diffuse through the plastic; high CO2 tends to decrease pH and reduce spoilage; tends to decrease pH and reduce spoilage; modified atmosphere packaging (MAP) involves modified atmosphere packaging (MAP) involves the use of modern shrink wrap materials and the use of modern shrink wrap materials and vacuum technology to package foods in a desired vacuum technology to package foods in a desired atmosphere (e.g., high CO2 or high O2)atmosphere (e.g., high CO2 or high O2)

Microbial Growth and Microbial Growth and Food SpoilageFood Spoilage

Meats and dairy products are ideal Meats and dairy products are ideal environments for spoilage by environments for spoilage by microorganisms because of their high microorganisms because of their high nutritional value and the presence of nutritional value and the presence of easily utilizable carbohydrates, fats, easily utilizable carbohydrates, fats, and proteins; proteolysis (aerobic) and proteins; proteolysis (aerobic) and putrefaction (anaerobic) and putrefaction (anaerobic) decompose proteins; in spoilage of decompose proteins; in spoilage of unpasteurized milk, a four-step unpasteurized milk, a four-step succession of microorganisms occurs succession of microorganisms occurs

Fruits and vegetables have much lower Fruits and vegetables have much lower protein and fat content then meats and protein and fat content then meats and dairy products and undergo different dairy products and undergo different kind of spoilage; the presence of readily kind of spoilage; the presence of readily degradable carbohydrates in degradable carbohydrates in vegetables favors spoilage by bacteria; vegetables favors spoilage by bacteria; high oxidation–reduction potential high oxidation–reduction potential favors aerobic and facultative bacteria; favors aerobic and facultative bacteria; molds usually initiate spoilage in whole molds usually initiate spoilage in whole fruitsfruits

Frozen citrus products are Frozen citrus products are minimally processed and can be minimally processed and can be spoiled by lactobacilli and yeastsspoiled by lactobacilli and yeasts

Grains, corn, and nuts can spoil when held under Grains, corn, and nuts can spoil when held under moist conditions; this can lead to production of moist conditions; this can lead to production of toxic substancestoxic substances Ergotism is caused by hallucinogenic alkaloids produced Ergotism is caused by hallucinogenic alkaloids produced

by fungi in corn and grainsby fungi in corn and grains Aflatoxins—planar molecules that intercalate into DNA Aflatoxins—planar molecules that intercalate into DNA

and act as frameshift mutagens and carcinogens; if and act as frameshift mutagens and carcinogens; if consumed by dairy cows, aflatoxins can appear in milk; consumed by dairy cows, aflatoxins can appear in milk; have also been observed in beer, cocoa, raisins, and have also been observed in beer, cocoa, raisins, and soybean meal; aflatoxin sensitivity can be influenced by soybean meal; aflatoxin sensitivity can be influenced by prior disease exposure (e.g., hepatitis B infection prior disease exposure (e.g., hepatitis B infection increases sensitivity)increases sensitivity)

Fumonisins—contaminants of corn; cause disease in Fumonisins—contaminants of corn; cause disease in animals and esophageal cancer in humans; disrupt animals and esophageal cancer in humans; disrupt synthesis and metabolism of sphingolipidssynthesis and metabolism of sphingolipids

Shellfish and finfish can be Shellfish and finfish can be contaminated by algal toxins, which contaminated by algal toxins, which cause a variety of illnesses in cause a variety of illnesses in humanshumans

Controlling Food Controlling Food SpoilageSpoilage

Removal of microorganisms—Removal of microorganisms—filtration of water, wine, beer, filtration of water, wine, beer, juices, soft drinks and other liquids juices, soft drinks and other liquids can keep bacterial populations low can keep bacterial populations low or eliminate them entirelyor eliminate them entirely

Low temperature—refrigeration Low temperature—refrigeration and/or freezing retards microbial and/or freezing retards microbial growth but does not prevent growth but does not prevent spoilagespoilage

High temperatureHigh temperatureCanningCanning

Canned food is heated in special containers Canned food is heated in special containers called retorts to 115°C for 25-100 minutes to called retorts to 115°C for 25-100 minutes to kill spoilage microorganismskill spoilage microorganisms

Canned foods can undergo spoilage despite Canned foods can undergo spoilage despite safety precautions; spoilage can be due to safety precautions; spoilage can be due to spoilage prior to canning, underprocessing spoilage prior to canning, underprocessing during canning, or leakage of contaminated during canning, or leakage of contaminated water through can seams during coolingwater through can seams during cooling

PasteurizationCkills pathogens and PasteurizationCkills pathogens and substantially reduces the number of substantially reduces the number of spoilage organismsspoilage organisms Low-temperature holding (LTH)—62.8°C for 30 Low-temperature holding (LTH)—62.8°C for 30

minutesminutes High-temperature short-time (HTST)—71°C for High-temperature short-time (HTST)—71°C for

15 seconds15 seconds Ultra-high temperature (UHT)—141°C for 2 Ultra-high temperature (UHT)—141°C for 2

secondsseconds Shorter times result in improved flavor and Shorter times result in improved flavor and

extended shelf lifeextended shelf life

Heat treatments are based on a Heat treatments are based on a statistical process involving the statistical process involving the probability that the number of probability that the number of remaining viable microorganisms remaining viable microorganisms will be below a certain level after a will be below a certain level after a specified time at a specified specified time at a specified temperaturetemperature

Water availability—dehydration Water availability—dehydration procedures (e.g., freeze-drying) procedures (e.g., freeze-drying) remove water and increase solute remove water and increase solute concentrationconcentration

Chemical–based preservationChemical–based preservationRegulated by the U.S. Food and Drug Regulated by the U.S. Food and Drug

Administration (FDA); preservatives are listed Administration (FDA); preservatives are listed as “generally recognized as safe” (GRAS); as “generally recognized as safe” (GRAS); include simple organic acids, sulfite, ethylene include simple organic acids, sulfite, ethylene oxide as a gaseous sterilant, sodium nitrite, oxide as a gaseous sterilant, sodium nitrite, and ethyl formateand ethyl formate

Effectiveness depends on pH; nitrites protect Effectiveness depends on pH; nitrites protect against against Clostridium botulinumClostridium botulinum, but are of some , but are of some concern because of their potential to form concern because of their potential to form carcinogenic nitrosamines when meats carcinogenic nitrosamines when meats preserved with them are cookedpreserved with them are cooked

Radiation—nonionizing (ultraviolet or Radiation—nonionizing (ultraviolet or UV) radiation is used for surfaces of UV) radiation is used for surfaces of food-handling utensils, but does not food-handling utensils, but does not penetrate foods; ionizing (gamma penetrate foods; ionizing (gamma radiation) penetrates well but must be radiation) penetrates well but must be used with moist foods to produce used with moist foods to produce peroxides, which oxidize sensitive peroxides, which oxidize sensitive cellular constituents cellular constituents (radappertization); ionizing radiation is (radappertization); ionizing radiation is used for seafoods, fruits, vegetables, used for seafoods, fruits, vegetables, and meatsand meats

Microbial product-based inhibitionMicrobial product-based inhibitionBacteriocins—bactericidal proteins produced Bacteriocins—bactericidal proteins produced

by bacteria; active against only closely by bacteria; active against only closely related bacteria (e.g., nisin)related bacteria (e.g., nisin)

Bacteriocins function by several Bacteriocins function by several mechanisms, including dissipation of proton mechanisms, including dissipation of proton motive force, formation of hydrophobic motive force, formation of hydrophobic pores in membranes, or inhibition of protein pores in membranes, or inhibition of protein and RNA synthesisand RNA synthesis

Food-borne DiseasesFood-borne Diseases

Food-borne illnesses impact the Food-borne illnesses impact the entire world; entire world;

are either infections or intoxications; are either infections or intoxications; are associated with poor hygiene are associated with poor hygiene

practicespractices

Food-borne infectionsFood-borne infections

Due to ingestion of Due to ingestion of microorganisms, followed by microorganisms, followed by

growth, tissue invasion and/or growth, tissue invasion and/or release of toxinsrelease of toxins

SalmonellosisSalmonellosis caused by a variety of caused by a variety of Salmonella Salmonella serovars; serovars; commonly transmitted by meats, poultry, and commonly transmitted by meats, poultry, and

eggs; eggs; can arise from contamination of food by workers can arise from contamination of food by workers

in food-processing plants and restaurantsin food-processing plants and restaurants

Campylobacter jejuniCampylobacter jejuni transmitted by uncooked or poorly cooked transmitted by uncooked or poorly cooked

poultry products, poultry products, raw milk and red meats; raw milk and red meats; thorough cooking prevents transmissionthorough cooking prevents transmission

ListeriosisListeriosistransmitted by dairy productstransmitted by dairy products

Enteropathogenic, enteroinvasive, Enteropathogenic, enteroinvasive, and enterotoxigenic and enterotoxigenic Escherichia coliEscherichia coliSpread by fecal-oral route; found in Spread by fecal-oral route; found in

meat products, in unpasteurized fruit meat products, in unpasteurized fruit drinks, and on fruits and vegetablesdrinks, and on fruits and vegetables

Prevention requires prevention of food Prevention requires prevention of food contamination throughout all stages of contamination throughout all stages of production, handling, and cookingproduction, handling, and cooking

Viral pathogensViral pathogens usually transmitted by water or by direct usually transmitted by water or by direct

contamination by food processors and handlers; contamination by food processors and handlers; recently Norwalk-like viruses have been recently Norwalk-like viruses have been

involved in major outbreaks on several large involved in major outbreaks on several large cruise shipscruise ships

Variant Creutzfeld-Jakob diseaseVariant Creutzfeld-Jakob disease transmitted by ingestion of beef from infected transmitted by ingestion of beef from infected

cattle; cattle; transmission between animals is due to the use transmission between animals is due to the use

of mammalian tissue in ruminant animal feeds; of mammalian tissue in ruminant animal feeds; prevention and control is difficultprevention and control is difficult

Foods transported and consumed in Foods transported and consumed in uncooked state are increasingly uncooked state are increasingly important sources of food-borne important sources of food-borne infection, especially as there is infection, especially as there is increasingly rapid movement of people increasingly rapid movement of people and products around the worldand products around the worldSprouts can be a problem if germinated in Sprouts can be a problem if germinated in

contaminated watercontaminated waterShellfish and finfish can be contaminated by Shellfish and finfish can be contaminated by

pathogens (e.g., pathogens (e.g., VibrioVibrio and viruses) found in and viruses) found in raw sewageraw sewage

Raspberries are often transported by air to Raspberries are often transported by air to far-away markets; if contaminated, outbreak far-away markets; if contaminated, outbreak occurs far from source of pathogenoccurs far from source of pathogen

Food intoxicationsFood intoxications Ingestion of microbial toxins in foods Ingestion of microbial toxins in foods

Staphylococcal food poisoning is caused by Staphylococcal food poisoning is caused by exotoxins released by exotoxins released by Staphylococcus aureusStaphylococcus aureus, , which is frequently transmitted from its normal which is frequently transmitted from its normal habitat (nasal cavity) to food by person’s hands; habitat (nasal cavity) to food by person’s hands; improper refrigeration leads to growth of bacterium improper refrigeration leads to growth of bacterium and toxin productionand toxin production

Clostridium botulinum, C. perfringens, Clostridium botulinum, C. perfringens, and and B. B. subtilis subtilis also cause food intoxicationalso cause food intoxication Botulism, caused by Botulism, caused by C. botulinumC. botulinum C. C. perfringensperfringens is a common inhabitant of food, soil, water, is a common inhabitant of food, soil, water,

spices and intestinal tract; upon ingestion, endospores spices and intestinal tract; upon ingestion, endospores germinate and produce enterotoxins within the intestine; germinate and produce enterotoxins within the intestine; this causes food poisoning; often occurs when meats are this causes food poisoning; often occurs when meats are cooked slowlycooked slowly

Bacillus cereusBacillus cereus food poisoning is associated with starchy food poisoning is associated with starchy foodsfoods

Detection of Food-borne Detection of Food-borne PathogensPathogens

Methods need to be rapid; therefore, traditional Methods need to be rapid; therefore, traditional culture methods that might take days to weeks culture methods that might take days to weeks to complete are too slowto complete are too slow

identification is also complicated by low identification is also complicated by low numbers of pathogens compared to normal numbers of pathogens compared to normal microfloramicroflora

chemical and physical properties of food can chemical and physical properties of food can make isolation of food-borne pathogens make isolation of food-borne pathogens difficultdifficult

Molecular methods are valuable for Molecular methods are valuable for three reasonsthree reasonsThey can detect the presence of a They can detect the presence of a

single, specific pathogensingle, specific pathogenThey can detect viruses that cannot be They can detect viruses that cannot be

conveniently culturedconveniently culturedThey can identify slow-growing or They can identify slow-growing or

nonculturable pathogensnonculturable pathogens

Some examplesSome examplesDNA probes can be linked to enzymatic, DNA probes can be linked to enzymatic,

isotopic, chromogenic, or luminescent/ isotopic, chromogenic, or luminescent/ fluorescent markers; are very rapidfluorescent markers; are very rapid

PCR can detect small numbers of PCR can detect small numbers of pathogens (e.g., as few as 10 toxin-pathogens (e.g., as few as 10 toxin-producing producing E. coliE. coli cells in a population of cells in a population of 100,000 cells isolated from soft cheese 100,000 cells isolated from soft cheese samples; as few as two colony- forming samples; as few as two colony- forming units of units of SalmonellaSalmonella); PCR systems are ); PCR systems are being developed for being developed for Campylobacter Campylobacter jejuni jejuni andand Arcobacter butzleri Arcobacter butzleri

Food-borne pathogen fingerprinting is Food-borne pathogen fingerprinting is an integral part of an initiative by the an integral part of an initiative by the Centers for Disease Control (CDC) to Centers for Disease Control (CDC) to control food-borne pathogens; The control food-borne pathogens; The CDC has established a procedure CDC has established a procedure (PulseNet) in which pulse-field gel (PulseNet) in which pulse-field gel electrophoresis is used under electrophoresis is used under carefully controlled and standardized carefully controlled and standardized conditions to detect the distinctive conditions to detect the distinctive DNA patterns of nine major food DNA patterns of nine major food pathogens; these pathogens are pathogens; these pathogens are being followed in an surveillance being followed in an surveillance network (FoodNet)network (FoodNet)

Microbiology of Microbiology of Fermented FoodsFermented Foods

Fermented milksFermented milksat least 400 different fermented milks at least 400 different fermented milks

are produced throughout the world; are produced throughout the world; fermentations are carried out by fermentations are carried out by

mesophilic, thermophilic, and mesophilic, thermophilic, and therapeutic lactic acid bacteria, therapeutic lactic acid bacteria,

as well as by yeasts and moldsas well as by yeasts and molds

MesophilicMesophilicacid produced from microbial activity at acid produced from microbial activity at

temperatures lower than 45°C causes temperatures lower than 45°C causes protein denaturation (e.g., cultured protein denaturation (e.g., cultured buttermilk and sour cream)buttermilk and sour cream)

ThermophilicThermophilicfermentations carried out at about 45°C fermentations carried out at about 45°C

(e.g., yogurt)(e.g., yogurt)

TherapeuticTherapeuticfermented milks may have beneficial fermented milks may have beneficial

therapeutic effectstherapeutic effectsAcidophilus milk contains Acidophilus milk contains L. acidophilus;L. acidophilus; improves improves

general health by altering intestinal microflora; general health by altering intestinal microflora; may help control colon cancermay help control colon cancer

Bifid-amended fermented milk products Bifid-amended fermented milk products (containing (containing BifidobacteriumBifidobacterium spp.) improve lactose spp.) improve lactose tolerance, possess anticancer activity, help tolerance, possess anticancer activity, help reduce serum cholesterol levels, assist calcium reduce serum cholesterol levels, assist calcium absorption, and promote the synthesis of B-absorption, and promote the synthesis of B-complex vitamins; may also reduce or prevent the complex vitamins; may also reduce or prevent the excretion of rotaviruses, a cause of diarrhea excretion of rotaviruses, a cause of diarrhea among childrenamong children

Yeast lacticYeast lacticthese fermentations include kefir, which these fermentations include kefir, which

is made by the action of yeasts, lactic is made by the action of yeasts, lactic acid bacteria, and acetic acid bacteriaacid bacteria, and acetic acid bacteria

Mold lacticMold lacticthis fermentation is used to make viili, a this fermentation is used to make viili, a

Finnish beverage; Finnish beverage; carried out by the mold carried out by the mold Geotrichium Geotrichium

candidumcandidum and lactic acid bacteria and lactic acid bacteria

CheesesCproduced by coagulation of CheesesCproduced by coagulation of curd, expression of whey, and curd, expression of whey, and ripening by microbial fermentation; ripening by microbial fermentation; cheese can be internally inoculated or cheese can be internally inoculated or surface ripenedsurface ripened

Meat and FishMeat and FishMeat products include sausages, country-Meat products include sausages, country-

cured hams, bologna, and salami; these cured hams, bologna, and salami; these fermentations frequently involve fermentations frequently involve Pediococcus Pediococcus cerevisiaecerevisiae and and Lactobacillus plantarumLactobacillus plantarum

Fish products include izushi (fresh fish, rice, Fish products include izushi (fresh fish, rice, and vegetables incubated with and vegetables incubated with LactobacillusLactobacillus spp.) and katsuobushi (tuna incubated with spp.) and katsuobushi (tuna incubated with Aspergillus glaucusAspergillus glaucus))

Production of Alcoholic Production of Alcoholic BeveragesBeverages

Wines and champagnesWines and champagnes

Grapes are crushed and liquids that contain Grapes are crushed and liquids that contain fermentable substrates (musts) are fermentable substrates (musts) are separated; musts can be fermented separated; musts can be fermented immediately, but the results can be immediately, but the results can be unpredictable; usually must is sterilized by unpredictable; usually must is sterilized by pasteurization or with sulfur dioxide pasteurization or with sulfur dioxide fumigant; to make a red wine, the skins of a fumigant; to make a red wine, the skins of a red grape are left in contact with the must red grape are left in contact with the must before the fermentation process; if must before the fermentation process; if must was sterilized, the desired strain of was sterilized, the desired strain of Saccharomyces cerevisiaeSaccharomyces cerevisiae or or S. ellipsoideusS. ellipsoideus is added, and the mixture fermented (10 to is added, and the mixture fermented (10 to 18% alcohol)18% alcohol)

Another important fermentative process that Another important fermentative process that occurs is the malo-lactic fermentation carried occurs is the malo-lactic fermentation carried out by out by LeuoconostocLeuoconostoc spp.; this fermentation spp.; this fermentation reduces the amount of organic acids (e.g., reduces the amount of organic acids (e.g., malic acid) in the wine, improving its flavor, malic acid) in the wine, improving its flavor, stability, and “mouth feel”stability, and “mouth feel”

For dry wine (no free sugar), the amount of For dry wine (no free sugar), the amount of sugar is limited so that all sugar is fermented sugar is limited so that all sugar is fermented before fermentation stops; for sweet wine before fermentation stops; for sweet wine (free sugar present), the fermentation is (free sugar present), the fermentation is inhibited by alcohol accumulation before all inhibited by alcohol accumulation before all sugar is used up; in the aging process sugar is used up; in the aging process flavoring compounds accumulateflavoring compounds accumulate

RackingCremoval of sediments accumulated RackingCremoval of sediments accumulated during the fermentation processduring the fermentation process

Brandy (burned wine) is made by distilling Brandy (burned wine) is made by distilling wine to increase alcohol concentration; wine wine to increase alcohol concentration; wine vinegar is made by controlled microbial vinegar is made by controlled microbial oxidation (by oxidation (by AcetobacterAcetobacter or or GluconobacterGluconobacter) ) to produce acetic acid from ethanolto produce acetic acid from ethanol

For champagnes, fermentation is continued For champagnes, fermentation is continued in bottles to produce a naturally sparkling in bottles to produce a naturally sparkling winewine

Beers and alesBeers and alesMalt is produced by germination of the Malt is produced by germination of the

barley grains and the activation of their barley grains and the activation of their enzymes; enzymes;

mash is produced from malt by mash is produced from malt by enzymatic starch hydrolysis to enzymatic starch hydrolysis to accumulate utilizable carbohydrates; accumulate utilizable carbohydrates;

mash is heated with hops (dried flowers mash is heated with hops (dried flowers of the female vine of the female vine Humulus lupulisHumulus lupulis) to ) to provide flavor and clarify the wort; provide flavor and clarify the wort;

hops inactivate hydrolytic enzymes so hops inactivate hydrolytic enzymes so that wort can be pitched (inoculated that wort can be pitched (inoculated with yeast)with yeast)

Beer is produced with a bottom Beer is produced with a bottom yeast, such as yeast, such as Saccharomyces Saccharomyces carlsbergensiscarlsbergensis and ale is produced and ale is produced with a top yeast, such as with a top yeast, such as S. S. cerevisiaecerevisiae; freshly fermented (green) ; freshly fermented (green) beers are lagered (aged), beers are lagered (aged),

bottled, and carbonated; bottled, and carbonated; beer can be pasteurized or filtered to beer can be pasteurized or filtered to

remove microorganisms and remove microorganisms and minimize flavor changesminimize flavor changes

Distilled spiritsCbeerlike fermented Distilled spiritsCbeerlike fermented liquid is distilled to concentrate liquid is distilled to concentrate alcohol; alcohol;

type of liquor depends on type of liquor depends on composition of starting mash; composition of starting mash;

flavorings can also be added; flavorings can also be added; a sour mash involving a sour mash involving LactobacillusLactobacillus

delbrueckiidelbrueckii mediated fermentation mediated fermentation is often usedis often used

Production of breadsProduction of breads

Aerobic yeast fermentation is used to Aerobic yeast fermentation is used to increase carbon dioxide production increase carbon dioxide production and decrease alcohol production; and decrease alcohol production; other metabolic products add flavorsother metabolic products add flavors

Other microorganisms make special Other microorganisms make special breads, such as sourdoughbreads, such as sourdough

Bread products can be spoiled by Bread products can be spoiled by BacillusBacillus species that produce ropiness species that produce ropiness

Other fermented foodsOther fermented foods

Sufu, fermented tofu (a chemically Sufu, fermented tofu (a chemically coagulated soybean milk product) and coagulated soybean milk product) and tempeh, made from soybean mash, tempeh, made from soybean mash, are made by the action of moldsare made by the action of molds

SauerkrautCfermented cabbage; SauerkrautCfermented cabbage; involves a microbial succession involves a microbial succession mediated by mediated by Leuconostoc Leuconostoc mesenteroides,mesenteroides, Lactobacillus Lactobacillus plantarumplantarum, and , and Lactobacillus brevisLactobacillus brevis

Pickles are cucumbers fermented in Pickles are cucumbers fermented in brine by a variety of bacteria; brine by a variety of bacteria; fermentation process involves a fermentation process involves a complex microbial successioncomplex microbial succession

Silages–animal feeds produced by Silages–animal feeds produced by anaerobic, lactic-type mixed anaerobic, lactic-type mixed fermentation of grass, corn, and fermentation of grass, corn, and other fresh animal feedsother fresh animal feeds

Microorganisms as Microorganisms as Foods and Food Foods and Food Amendments Amendments

Microbes that are eaten include a Microbes that are eaten include a variety of bacteria, yeasts, and variety of bacteria, yeasts, and other fungi (e.g., mushrooms, other fungi (e.g., mushrooms, SpirulinaSpirulina))

ProbioticsProbioticsthe addition of microorganisms to the the addition of microorganisms to the

diet in order to provide health benefits diet in order to provide health benefits beyond basic nutritive valuebeyond basic nutritive value

also called microbial dietary also called microbial dietary adjuvantsadjuvants

PrebioticsPrebioticsoligosaccharide polymers that are not oligosaccharide polymers that are not

processed until reaching the large processed until reaching the large intestine;intestine;

often combined with probiotics to create a often combined with probiotics to create a synbiotic systemsynbiotic system

Probiotics Probiotics are being used with poultry to increase are being used with poultry to increase

body weight and feed conversion; body weight and feed conversion; also reduce coliforms and also reduce coliforms and CampylobacterCampylobacter; ;

may be useful in preventing may be useful in preventing SalmonellaSalmonella from colonizing gut due to competitive from colonizing gut due to competitive exclusionexclusion