D

The aflatoxin biosynthetic pathway in toxigenic Aspergillus. The 82 kb aflatoxin gene cluster from A. parasiticus and A. flavus is shown in panel A (new names on the left and old names on the right). The gene cluster coding for sugar utilization is also shown. The direction of gene transcription is shown along the vertical line. The encoded aflatoxin biosynthetic enzymes are shown in panel B, along with the aflatoxin (middle column) and sterigmatocystin (far right) pathways....

History

The history of wine is nearly as old as the history of human civilization.The earliest writings discovered on the walls of ancient caves and in buried artifacts contain images of wine and wine-making instruments. Wine is mentioned more than 100 times in both the Hebrew and Christian bibles and many of the most well-know passages involve wine. The very first vines, for example, were planted by Noah, who presumably was the first wine maker later Jesus performed the miracle of turning water into...

Info

Phylogeny of Bifidobacterium based on 16S rRNA sequence analysis. tirely different phylum (Actinobacteria). Bifi-dobacteria are Gram positive, non-motile, non-sporing rods with a high G+C content (55 to 67 mol ). Cells often occur in pairs with a Vor Ylike appearance. They are strictly anaerobic and catalase negative, with a temperature optima between 37 C and 41 C and a pH optima (for growth initiation) between 6.5 and 7.0. Bifidobacteria are nutritionally fastidious and require...

Wine Basics

Although wine making, like beer manufacture, involves an alcoholic fermentation, the similarities, for the most part, end there. The wine fermentation requires different yeasts and substrates and yields distinctly different products. And whereas beer is best consumed fresh, most wines improve markedly during an aging period that can last for many years. Finally, although most wines, like most beers, start with relatively inexpensive raw materials, the quality of premium wines depends, more so...

Pickle fermentation

As noted above, the high salt concentrations used in pickle manufacturing cause the fermentation to proceed quite differently from Box 7 3. Starter Cultures and Fermented Vegetables The modern manufacture of most fermented vegetables, in contrast to cheese, sausage, and other fermented food products, still relies on a natural fermentation. In large part, this is because vegetable fermentations occur as a succession, and duplicating this process with controlled fermentations using starter...

G7

States.Yogurt accounts for more than half of all cultured dairy products consumed in the United States (Figure 4-1), with nonfat and low-fat versions being the most popular (about 90 of total yogurt sales). Per capita consumption of buttermilk in the United States has decreased nearly 50 in the past twenty years, but consumption of sour cream (including sour cream-based dips) has doubled and yogurt has tripled during that same time. Nonetheless, total per capita consumption for all cultured...

Fut C D B A Rshjemn Gl Io P Q K Vwxy

Linear arrangement of the afl gene cluster from Aspergillus parasiticus. Individual gene names are abbreviated by a single letter (where aflR R), and are named according to the scheme proposed by Yu et al., 2004B. Genes described in the text include pksA (aflC), aflJ (aflS), norA (aflE), avfA (afl ), and omtB (aflO). Four genes at the 3' end of the afl cluster encode for a sugar utilization pathway, followed by a fifth gene whose function is unknown. Adapted from Yu et al., 2004A and...

Sugars

Other than water, which is 70 to 85 of the total juice volume, simple sugars represent the largest constituent of grapes or must. Depending on the maturation of the grape at harvest, must usually contains equal concentrations of glucose and fructose, with the latter increasing somewhat in over-ripened grapes. Sucrose is usually present at very low concentrations (less than 1 ), except for musts from V labrusca grapes, which can contain as much as 10 sucrose. In general, most grape cultivars...

Cheese Ripening

Freshly made cheese has essentially none of the flavor, aroma, rheological, or appearance properties of aged or ripened cheese. Rather, the metamorphosis from a bland, pale, rubbery mass of protein and fat into a flavorful, textured fusion of complex substances takes time and requires patience. Although efforts to reduce aging time and accelerate the ripening process have been somewhat successful (see below), for the most part, cheese ripening is a sequential process, with each step relying on...

Meat Composition

Fresh meat is a nutrient-rich medium and is, in fact, one of the best for supporting growth of microorganisms. Skeletal bovine muscle contains nearly 20 of high quality protein, about 2 to 3 lipid, and a small amount of carbohydrate, non-protein nitrogen, and inorganic mate-rial.The balance, about 75 , is water, so the water activity (aw), not surprisingly, is nearly 0.99. The pH of the fresh tissue, before rigor, is 6.8 to 7.0, but decreases to about 5.6 to 5.8 following rigor, due to...

Oenococcus

This genus was established as recently as 1995, and contains only one species, O. oeni. Not surprisingly, O. oeni is located, phylogenetically, within the Leuconostocaceae branch however, it is somewhat distant from Leuconostoc and Weissella (Figure 2-2). Although O. oeni shares many phenotypic properties with Leu-conostoc sp. (e.g., heterofermentative metabolism, mesophilic growth range), several important physiological differences exist. In particular, O. oeni is much more acid-tolerant than...

Fermentation

The wine fermentation begins as soon as the grapes are crushed. However, when a starter culture is used and SO2 is added to control the indigenous organisms, limited ethanol fermentation will occur prior to addition of the culture. In the case of white wine production, the culture is added to the must after pressing and clarification, whereas for red wine, culture addition is done prior to seed and skin removal.Thus, for red wines, fermentation occurs during maceration, just as it would for a...

Metabolism and Fermentation

The acetic acid pathway used by Acetobacter, Gluconobacter and other acetic acid bacteria is an example of what is referred to as an incomplete oxidation.Whereas in most oxidative pathways (e.g., the Krebs or citric acid cycle), organic substrates are ordinarily oxidized all the way to CO2 and H2O, in the vinegar fermentation, acetic acid bacteria usually oxidize the substrate, ethanol, only to acetic acid. However, as described below, exceptions exist where complete oxidation to CO2 can occur....

Ethanol

Would be the last sugar fermented in this mixture. Depending on how the cells had previously been grown, however, it is possible that invertase had already been induced, resulting in rapid formation of sucrose hydrolysis products. Finally, there exist strains of S. cerevisiae whose expression of cata-bolic genes is constitutive, meaning that they are not subject to catabolite repression. Such strains may be particularly useful, since constitutive expression of genes coding for maltose permease...

Culture metabolism

S. thermophilus and L. delbrueckii subsp. bul-garicus both make lactic acid during the yogurt fermentation.They are homofermentative, meaning lactic acid is the primary end-product from sugar metabolism, and both ferment lactose in a similar manner. Moreover, the specific means by which lactose metabolism occurs in these bacteria not only dictate product formation, but also have an important impact on the health-promoting activity these bacteria provide (discussed later). The first step...

History and Evolution of the Fermented Meats Industry

Like other fermented foods, recorded references to fermented meats date back thousands of years. The manufacture of these products likely originated in southern Europe and areas surrounding the Mediterranean Sea during the Roman era, although there were probably Asian counterparts that appeared around the same time. Even though it is not absolutely clear from the historical records whether these early sausage products were actually fermented, it is difficult to imagine, given the circumstances,...

Kettle Boil

After the hops are added to the wort, the mixture is boiled for one to one-and-a-half hours. Boiling accomplishes at least seven functions. First, it kills nearly all of the microorganisms remaining after mashing, making the wort, for all practical purposes, sterile. Second, boiling inactivates most of the enzymes still active after mashing or reduces their activity to barely detectable levels.Third, the boiling step enhances extraction of oils and resins from the hops and accelerates...

Factors affecting growth

Temperature and relative humidity have an important effect on yeast growth and fermentative capacity. Most strains of S. cerevisiae used for baking have an optimum temperature of about 36 C to 39 C, although seldom are such high temperatures used during the dough fermentation. Rather, doughs are ordinarily held at temperatures of about 25 C to 28 C (and sponges slightly lower). Although higher temperatures can accelerate fermentation and gassing rates (defined as the amount of CO2 produced per...

Microbial Ecology and Spontaneous Wine Fermentations

In the absence of SO2 addition, the indigenous microflora is relied upon to initiate and then carry out a spontaneous or natural fermenta-tion.This is one of the most well studied of all fermentations, and much is now known about the ecology of wine and the yeasts that participate in the wine fermentation. In reality, however, the yeast fermentation is but one of two distinct fermentations that occur in wine making. Yeasts, of course, ferment sugars to ethanol, CO2, and small amounts of other...

Brevibacterium

The genus Brevibacterium (phylum, Actinobac-teria) are described as non-motile, non-sporing, non-acid-fast, irregular-shaped organisms that belong to the coryneform group. Like other coryneform bacteria, Brevibacterium sp. are Gram positive rods, but both their staining pattern and shape can vary, depending on the age and condition of the cells. They also are high G+C organisms (60 to 67 mol ). Brevibac-terium are strictly aerobic, catalase-positive mesophiles, with an optimum growth...

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Representative phenolic compounds in wine. Examples include a. cinnamic acid, a phenolic acid b. resveratrol, a derivative of cinnamic acid c. catechin, a flavan-3-ol d. gallic acid, a tannin e. quercetin, a flavonol and f. malvidin, an anthocyanin. means that the concentrations of sugars and acids (and the sugar acid ratio), pH, the total soluble solids, and even the phenolic constituents must be at just the right level for the particular cultivar and the type of wine being made....

Whitemold Ripened Cheese

The white mold-ripened cheeses, of which Camembert and Brie are the most well-known, are primarily made in France, where they are also among the most popular. These cheeses vary only slightly Camembert is made principally in the Normandy region of France, whereas most Brie is produced in Melun and Meaux, just outside of Paris. Brie wheels are usually a bit larger, with bacteria on the surface contributing to flavor development. Although similar versions of both Brie and Camembert are made in...

Grape Composition

Given that the two major constituents of wine, water and ethanol, have no flavor, color, or aroma, it is not surprising that the other grape components contribute so much to the organ-oleptic properties of wine. Some of these substances can be problematic, causing a variety of defects. In addition, the composition of grapes changes during growth and maturation on the vine, such that the time of harvest influences the chemical constituents of the grape as well as the wine.For example, the sugar...

Sparkling wines

Sparkling wines are those which contain carbon dioxide, providing bubbles and effervescence. For some sparkling wines, CO2 pressures as high as 600 kPa atmospheres can be reached (by comparison, the pressure inside a can of soda pop is less than 200 kPa).Although sparkling wines are made throughout the world, there are several manufacturing methods that are used to produce the CO2, and these methods define, to a certain extent, the type of sparkling wine being produced. Clearly, the most well...

Sulfur Dioxide Treatment

This is now a convenient point at which to discuss the use of sulfur dioxide and pure culture technique for wine making. As soon as the in tegrity of the grapes has been compromised by the crushing step, the sugars in the juice are liberated and made available for whatever microorganisms happen to be present. Ordinarily, the must is populated by epiphytic yeasts (that is, yeasts that reside on the surface of the grapes) and by yeasts that have contaminated the crushers, presses, and other...

Vinegar Technology

The first step in the manufacture of vinegar, as noted earlier, is the production of an ethanolic substrate. For the most part, the relevant fermentations (i.e., wine and beer) are discussed separately (Chapters 9 and 10). However, it is worth noting that ethanol from musts, ciders, or malt mashes are usually prepared with the eventual end product (i.e., vinegar) in mind. Thus, the starting materials do not necessarily have to be of the highest quality. However, this does not mean that poor...

Manufacture of sake

Sake is different from other wine fermentations in at least two main respects. First, as noted above, fermentable sugars are absent in rice, the sake substrate. Thus, it is necessary to provide exogenous enzymes, in the form of a koji, that can hydrolyze starch to simple sugars that the yeasts can ferment. This part of the sake manufacturing process, therefore, shares similarity with the beer-brewing process, in which malt is used to convert the starch (in barley) to simple sugars. The other...

Microorganisms

Aside from those bacteria that produce acetic acid as an overflow or side reaction from sugar metabolism (e.g., lactic acid bacteria), there are several genera of bacteria that produce acetic acid as the primary metabolic end product. It is important, however, to distinguish between those that produce acetic acid from one-carbon precursors and those that produce acetic acid via oxidation of ethanol. The former group are referred to as acetogens and include species of Clostridium, Eubac- terium,...

Sugar metabolism by bakers yeast

Because several sugars are ordinarily present in the dough (mainly glucose and maltose), and others may be added (sucrose, high fructose corn syrup), the yeast has a variety of metabolic substrates from which to choose. In addition, more maltose may be formed in the dough during the fermentation step via the successive action of endogenous a- and p-amylases present or added to the flour and that act on damaged starch granules.The order in which these different carbohydrates are fermented by S....

Tempeh Microbiology

The surface of raw soy beans contains an assortment of Gram positive and Gram negative bacteria, including Lactobacillus casei and other lactic acid bacteria enterococci, staphy-lococci streptococci bacilli Enterobacter, Klebsiella, and other coliforms.Yeasts, such as Pichia, Saccharomyces, and Candida, may also be present. During the soaking step, sucrose, stachyose, and raffinose diffuse out of the beans and into the water.Their subsequent hydrolysis by invertases and glucosidases releases...

Wine Spoilage and Defects

It can reasonably be said that as many things that can go right during wine manufacture, just as many can go wrong. The risk is exacerbated by the considerable investment that must be made to produce the wine (thus the old joke How does one make a million dollars in the wine business Start with 2 million). Grapes must be cultivated over several seasons before a reasonable crop can be harvested. Disease, climate, insects, and other factors can cause serious...

Open vat process

The open vat process relies on surface growth of acetic acid bacteria in vats, barrels, jars, or Box 11 2. The Special Appeal of Specialty Vinegars (or, You Paid How Much for That Vinegar ) By far, most of the vinegar produced in the United States is used by the food industry in the manufacture of salad dressings, pickles, catsup, mustard, and a variety of other processed foods. In general, the vinegar used for these products should be inexpensive and plain-tasting. Even the more flavorful...

Manufacture of Soy Sauce and Related Products

Soy sauce is one of the most widely consumed products in Asia. In Japan, per capita consumption is more than 10 liters per person per year, or more than 30 g per day. Dozens of different types of soy sauces are manufactured in Asia. In fact, even within the same country, there may be several distinct products, each having their own particular qualities and each made according to specific manufacturing procedures (Table 12-1). Moreover, quality standards further distinguish one product type from...

Acetate

Metabolism of pyruvate to acetate in Clostridia. The phosphoroclastic conversion of pyruvate to acetate is mediated by several iron-containing proteins. Pyruvate-ferridoxin oxidoreductase oxidizes pyruvate, using ferridoxin (Fd) as the electron acceptor. Reduced ferridoxin is then re-oxidized by a third iron-containing protein, hydrogenase. Protons serve as the electron acceptor, and hydrogen gas is formed. Phospho-transacetylase and acetate kinase catalyze the final two steps, with...

Bacteria Used in the Manufacture of Fermented Foods

Despite the diversity of bacteria involved directly or indirectly in the manufacture of fermented foods, all are currently classified in one of three phyla, the Proteobacteria, Firmicutes, and the Actinobacteria. Within the Firmicutes are the lactic acid bacteria, a cluster of Grampositive bacteria that are the main organisms used in the manufacture of fermented foods. This phylum also includes the genera Bacillus and Brevibacterium that contain species used in the manufacture of just a few...

Sulfur and Nitrogen Metabolism

Although metabolism of carbohydrates is obviously critical to the outcome of the wine fermentation, metabolism of other must components is also important. How wine yeasts metabolize sulfur-containing compounds that are present in the must as normal grape constituents is particularly important. Most of the sulphur in grapes is in the form of elemental sulfur, sulfates, or as sulfur-containing amino acids. Since the range of sulfur-containing metabolic end products includes various sulfides,...

Spoilage bacteriophages and other problems

Spoilage of vinegar by microorganisms is rare, although aceto-tolerant fungi, such as Monil-iella acetoabutens, have occasionally been known to grow in raw vinegar. The more common problem, at least for open vat or trickling type processes, is the occasional contamination with mites and flies. The vinegar eel, in particular, was once quite common, especially in traditional open vat or trickling fermentation systems, but is now infrequently present.The eel is actually a small worm (i.e., a...

Manufacture of Sake and Rice Wines

As noted in Chapter 10, most wines produced throughout the world rely on grapes as the starting raw material. Grapes used for wine making ordinarily contain an ample amount of glucose and fructose, which are readily fermented by the endogenous yeasts or added pure yeast cultures. In contrast, when starchy substrates, such as rice, are used as the raw material, the complex polysaccharides (mainly amylose and amy-lopectin) must first be hydrolyzed to produce fermentable sugars.When rice wines...

Tempeh cultures

As noted above, the primary fermentation is mediated by growth of R. oligosporus, which can be added to the soy beans in one of several different forms. First, it can be added as a pure spore culture. Recommended strains include NRRL 2710 and DSM 1964, both isolated from Indonesian tempeh and both available from public culture collections. Like the commercial strains used for other fungal-fermented products, tempeh starter cultures should be selected based on specific phenotypic traits (Table...

Spoilage and defects

In Indonesia, where tempeh is consumed on a near-daily basis, spoilage is not much of an issue, provided the product is eaten within a day or two of manufacture. However, the shelf-life of tempeh held at room temperature is very short, owing to the continued growth of the mold and bacteria. Once R. oligosporus begins to sporulate and produce colored sporangia, the product's shelf-life is essentially finished. Even when stored at refrigeration temperatures, mold growth is slowed but not stopped....

Tempeh biochemistry

In addition to producing the mycelia mass that literally holds the soy beans together, R. oligosporus is also responsible for causing major biochemical changes in the composition of the soy bean substrate (Table 12-8). In particular, lipids and proteins serve as substrates for fungi-excreted lipases and proteinases, respectively. During the incubation period, about a third of the lipid and a fourth of the protein fractions are degraded. Lipid hydrolysis results mainly in mono- and diglycerides,...

Yeast Metabolism

It should be evident by now that the main job of the yeasts during wine manufacture is to produce ethanol from the sugars present in the juice. However, if ethanol was the only product formed and if sugars were the only substrates metabolized by the yeast, then wine flavor and aroma would be sorely lacking. In fact, yeast growth and fermentation results in a myriad of metabolic end products that contribute, for better or worse, to the organoleptic properties of the finished wine. The main wine...

Tempeh

Tempeh is a mold-fermented soy bean product that originated many centuries ago in Indonesia, where it remains a major food staple and an inexpensive source of dietary protein. Unlike other fermented soy products, tempeh produc tion has spread to only a few other countries, including Malaysia, the Netherlands (Indonesia was once under Dutch rule), Canada, and the United States. However, Indonesia is by far the main producer and consumer of tempeh. Current per capita consumption in Indonesia is...

Trickling generator processes

In the vinegar fermentation, the rate at which ethanol is oxidized to acetic acid depends on the presence and availability of oxygen and the surface area represented by the air-liquid interface. In other words, the ability of acetic acid bacteria to perform the acetic acid fermentation is limited primarily by the diffusion or transport of oxygen from the atmosphere to the cell surface. It is possible to significantly accelerate the oxidation of ethanol by increasing the surface area to which...

Spoilage by bacteria

Probably the most common and most disastrous types of microbial spoilage of wine are those caused by bacteria.Two distinct groups are of importance the acetic acid bacteria and the lactic acid bacteria, both of which contain species able to tolerate the low pH, high ethanol conditions found in wine.These bacteria are responsible acidic and other end products that seriously affect wine quality. The acetic acid bacteria that are most important in wine spoilage belong to one of three genera...

Nutritional Benefits of Yogurt

One of great all-time television commercials aired in the late 1970s and featured an interview with a Russian centagenerian who claimed that his longevity was due to his daily consumption of yogurt. When asked who got him started on his yogurt regimen, he proudly stated it was his mother, who's smiling face then moves into the television frame. Indeed, the popularity of yogurt, as implied by this advertisement and as mentioned previously in this chapter (Box 4-1), has long been due, in large...

Fermentation Principles

In contrast to the lactic acid fermentation that occurs in milk, the meat fermentation has been, until recently, considerably less well studied and understood. In fact, the use of pure, defined starter cultures in the fermented meats industry is a relatively recent development (begun only in the 1950s and '60s). Before the use of meat starter cultures, the most common way to start the fermentation practice was, as noted above, backslopping. Backslopping works for several reasons. First,...

Manufacture of fish sauces and pastes

Extensive Flow Chart

The general procedure for the production of fish sauces is not complicated.The starting material can be small (< 15 cm in diameter) fish, Table 12.9. Types of fish sauces and pastes. Table 12.9. Types of fish sauces and pastes. such as sardines (that otherwise have minimal commercial value), small shrimp, squid, or oysters (Figure 12-7). Fish is usually used whole and uneviscerated, although de-headed, eviscerated, ground, or cut-up pieces can also be used. The only other ingredient necessary...

Manufacture of tempeh

The industrial manufacture of tempeh is quite simple, although numerous variations exist, depending largely on the scale of production, geographical and climatic considerations, and manufacturer preferences. The only raw material is soy beans, the fermentation time is short, and there is no aging or ripening period involved. In fact, the entire start-to-finish process is less than forty-eight hours.Tempeh can be considered as solid-state fermentation in that it consists of soy beans that are...

Cultured Dairy Products

. . . during recent years, attention has been directed to soured milk to such an extent that it has become necessary for all who are interested in the handling of milk and milk products to have a knowledge of the subject, as it seems clearly demonstrated that, under proper direction, there is every possibility of its forming an important element in the prolongation of life. From The Bacillus of Long Life by Loudon Douglas, 1911 Milk fermentations must undoubtedly be among the oldest of all...

Pump

Trickling generator system. passed, with aeration, into Tank 2, and back and forth until all of the ethanol is converted to vinegar.About three days are required to convert a 12 (v v) ethanol solution to a vinegar containing 10 to 12 acetic acid. Many modern trickling generator-type systems have been developed over the past seventy years based on the same principle as described above, but with more control and operational features. The Frings generator, introduced in the 1930s, and...

Curing agents

Finally, with few exceptions, fermented meat products include nitrite or nitrate as curing agents.These are added as either the sodium or potassium salt. Although nitrite salts are now used far more frequently, until the 1970s, nitrate salts were more common. For reasons discussed previously, some sausage manufacturers, still prefer nitrate. In any case, nitrite is added at a maximum of 156 ppm for dry and semi-dry sausages. Since a single ppm translates to 1 gram per 1,000 kg, only 156 grams...

Sulfur Compounds

Several sulfur-containing substances are found or are formed in grape juice that have a pronounced affect on the wine fermentation and wine quality. Hydrogen sulfide (H2S) and various organic forms of sulfur, especially the mer-captans which are formed from H2S, impart highly offensive odors in the wine. They are produced in trace amounts by grape yeasts during fermentation. The other major group of sulfur compounds found in wine are sulfur dioxide (SO2) and related aqueous forms that exist as...

Packaging and pasteurization

Following carbonation, the beer is ready to be packaged. Perhaps the simplest form of packaging is to fill the beer directly into kegs. Kegs are constructed of aluminum or stainless steel and vary in size between 50 L and 100 L. Kegs not only mimic the traditional cask-style beers (in terms of perceived quality), but provide a convenient means of delivering non-bottled or canned product to the consumer.Thus,kegs are widely used by bars and restaurants for serving draught (otherwise known as...

Chorleywood process

In the United Kingdom, the Chorleywood process is also a rapid, high throughput method and is probably the main commercial system for bread manufacture (Figure 8-9). It is little used, however, in the United States. This is a no-time process in which rapid mixing is a critical feature. Whatever fermentation there is, prior to the final proof, occurs during the brief floor time (at temperatures near 40 C).Thus,the start-to-finish process takes only two hours. Most yeast breads have a slightly...

Safety of Fungal Fermented Foods

There are two main reasons why the safety of Asian, fungal-fermented foods has been questioned. First, the Aspergillus sp. used in the production of soy sauce, miso, sake, and related products are taxonomically similar to the my-cotoxigenic aspergilli that produce aflatoxins, ochratoxin, and other toxins. Despite these similarities, however, surveys in which these foods have been analyzed for the presence of myco-toxins indicate that mycotoxins are not present. Recent studies have shown that...

Brandy

Brandy is produced by distilling wine.The wine can be made from other fruits, but when made from grapes, white wines are used as the base. The most well known brandy is Cognac, made from the Cognac district of France. In the United States, brandy must conform to a standard of identity that describes the starting fruit or juice, the ethanol concentration, the duration of aging, and other compositional and manufacturing details. Most American beverage-type brandies contain less than 50 ethanol...

Fish sauce microbiology

While it is evident that microorganisms are present during the production of fermented fish sauces, it is not clear to what extent these organisms contribute to the finished product. The microbial population in raw, unsalted fish and shellfish is high in number and rich in diversity. Considering the fact that whole unevis-cerated fish (guts and all) are usually used to make fish sauces, the initial load of organisms is significant. In addition, the manufacturing environment is not aseptic, and...

Biotechnology and the Brewing Industry

For the first 5,000 years that humans made and consumed beer, little was known about the actual scientific principles involved in its manufacture. Beer making was an art, practiced by craftsmen. Only in the last 150 years have biochemists and microbiologists identified the relevant organisms and metabolic pathways involved in the beer fermentation. In the past ten years alone, the entire genome of Saccharomyces cerevisiae (albeit, a lab strain, not an actual brewing strain) has been sequenced,...

Beer Manufacturing Principles

Only four ingredients are necessary to make beer water, malt, hops, and yeast. Despite its ancient origins and long history, and this seemingly short list of ingredients, the manufacture of a quality beer remains a rather challenging task. In part, this is because beer making consists of several different and distinct processes that are not always easy to control. In addition, some steps taken to improve one aspect of the process for example, filtering the finished beer to enhance clarity may...

Beer Spoilage and the Origins of Modern Science

Most fermentation microbiology students are aware that cheese, sausage, and other fermented foods evolved, in part, because these products had unique and desirable sensory characteristics. Likewise, they might also appreciate the many pleasant attributes of malted and hopped beverages. However, it is important to recognize that, while our ancestors undoubtedly enjoyed beer for many of the same reasons as today's consumers,they also understood that beer, like other fermented foods, was somehow...

Viticulture and Grape Science

The starting material for most wines, as noted above, is grapes.The main wine grape grown in temperate zones throughout the world is Vitis vinifera. Another grape, Vitis labrusca, grows well in northern regions in the United States and is frequently used for Concord varieties. It is important to note that, despite the existence of only a few major grape species, there are many different grape cultivars grown throughout the world. For example, Cabernet Sauvi-gnon, Chardonnay, Gamay, Mission,...

Nitrogenous Compounds

Grapes contain both inorganic and organic sources of nitrogen.Total nitrogen concentrations in grapes (or musts) range from about 0.2 g L to 0.4 g L.The ammonium nitrogen is less than 0.1 g L. Despite their relatively low concentration in juice, the nitrogen content of most musts is generally adequate for rapid growth of yeasts. In fact, the primary role of nitrogen in wine appears to be as a nutrient source for the yeasts, rather than affecting any of the organoleptic or other properties of...

Saccharomyces

It can reasonably be argued that the yeasts belonging to the genus Saccharomyces are among the most important of all organisms used in fermented foods, perhaps more so than even the lactic acid bacteria.These yeasts are required, after all, for the production of beer, wine, and spirits (not to mention bread), products that have a combined, world-wide economic impact in the trillions of dollars. In addition, the main species, Saccharomyces cerevisiae, is widely used as a model organism in...

Koji and Tane Koji Manufacture

First, it is necessary to recognize there are many types of koji used in the Far East, and that each fermented food requires a specific type of koji.Thus, Japanese soy sauces generally use a koji that is different from the one used to make Chinese-style soy sauces, and both are different from the koji used for sake manufacture. Generally, koji can be referred to by its intended product (e.g., sake koji or shoyu koji) or by the substrate from which the koji is prepared (e.g., rice koji, barley...

Micrococcaceae Cultures

Most meat starter cultures available in the United States contain species belonging to two genera of lactic acid bacteria, Lactobacillus and Pediococcus. In Europe, a quite different type of starter culture has been used. Most of the cultures used for European or European-style fermented sausages contain not only lactic acid bacteria, but also totally unrelated organisms belonging to the family Micrococcaceae.These include species of coagulase-negative Staphylo-coccus, Micrococcus, and Kocuria....

Tetragenococcus

Like the pediococci, Tetragenococcus are ho-mofermentative, tetrad-forming, facultative anaerobes. They are mesophilic and neu-traphilic, with temperature optima generally between 25 C and 30 C and pH optima between 6.5 and 8.0. The genus contains only three species, Tetragenococcus halophilus, Tetragenococcus muriaticus, and Tetrageno-coccus solitarius. Based on 16S rRNA sequences, these bacteria are phylogenetically more closely related to Lactobacillus and Ente-rococcus, than to Pediococcus....

Kimchi

As noted previously, the Korean version of sauerkraut is called kimchi. Although the manufacture of kimchi and sauerkraut are very similar, the characteristics of the finished products are quite different. The main difference between sauerkraut and kimchi is that the latter product contains ingredients other than simply cabbage and salt. Kimchi, for example, is usually made from cabbage, but other vegeta Table 7.4. Microbial defects in fermented vegetables. Table 7.4. Microbial defects in...

Natto

Natto is another soybean-fermented product consumed mainly in Japan, but similar products are also produced in China, Thailand, and the Philippines. Per capita consumption in Japan is about 1.2 Kg per person per year or 3 g per day. Natto is used as a condiment or flavoring agent, usually for rice and vegetables or as an ingredient in sushi. Nutritionally, natto is comparable to other fermented soybean products. It contains 16 to 18 protein 45 on a dry basis , with good digestibility and...

Whey Utilization

As shown earlier in this chapter Figure 5-4 , water, in the form of whey, is released when milk is converted into cheese. In fact, the whey accounts for 90 of the original milk volume. The dilute nature of the whey about 92 to 94 water and low protein concentration lt 1 have historically contributed to the perception at least in the United States that whey has little economic value. However, in other parts of the world, whey is more widely used, especially in the manufacture of whey-derived...

Phenols Tannins and Pigments

Among the most important naturally occurring substances in grapes and musts are the phenolic and polyphenolic compounds. Some phenols can also be introduced into the wine following aging in wooden casks or via yeast and bacterial metabolism.These chemically diverse compounds contribute color, flavor, aroma, and mouth feel to the wine. They can also react with other grape components and can either improve or diminish wine quality. Finally, many of the phenolic compounds found in wine are thought...

Introduction

Perhaps no other fermented food starts with such a simple raw material and ends up with products having such an incredible diversity of color, flavor, texture, and appearance as does cheese. It is even more remarkable that milk, pale in color and bland in flavor, can be transformed into literally hundreds of different types of flavorful, colorful cheeses by manipulating just a few critical steps. How so many cheeses evolved from this simple process undoubtedly involved part trial and error,...

Trichinella In Fermented Meats

Antimicrobial barriers in fermented meats. Property Level, range, or function Box 6-3. Pathogens, Toxins, and the Safety of Fermented Sausage Continued The problem, however, is now more complicated, because it has been recognized recently that some pathogens appear to be tolerant even to multiple barriers. Some strains of E. coli O157 H7, for example, are much more tolerant to low pH and organic acids than are normal E. coli strains. Furthermore, L. monocytogenes is resistant to low...

The Flavor of Soy Sauce

Considering that most soy sauces contain up to 18 NaCl, the most immediate and obvious flavor one detects is saltiness. However, the flavor of soy sauce is far more complex than simply saltiness. In fact, the shoyu products listed in Table 12-2 all contain between 16 and 19 salt, yet their flavor profiles, and the concentrations of volatile flavor compounds, can vary considerably. Nearly 200 volatile flavor components have been identified in shoyu, using GC or GC MS analysis. Several of these,...

Types of Asian Fermented Foods

There are hundreds of different types of fermented foods produced in China, Japan, the Philippines, and throughout Asia Beuchat, 2001 . However, there are two general types of fermented foods that are associated with or are indigenous to Eastern or Asian cuisines those that are plant-based and those that are fish-based.The former are made using primarily soy and rice as substrates, but other grains and legumes are also used. For the most part, these soy-based fermentations have been...

Bibliography

Kunkee, C.S.Ough,V.L. Singleton, A.D. Webb. 1980. The Technology of Wine Making, 4th Ed.,Avi Publishing Company, Inc.,Westport, Connecticut. Bartowsky, E.J., and P.A. Henschke. 2004.The buttery' attribute of wine-diacetyl-desirability, spoilage and beyond. Int.J. Food Microbiol. 96 235-252. Boulton, R.B.,VL. Singleton, L.F. Bisson, and R.E. Kunkee. 1996. Principles and Practices of Winemak-ing. Chapman and Hall, New York, New York. Coates, C. 2000. An Encyclopedia...

Tempeh nutrition and safety

Among the most important changes that occur during the tempeh fermentation are those that affect the nutritional quality of tempeh. As noted above, the concentration of the major macronutrients i.e., protein, fat, and carbohydrates decreases as the soybeans are converted to tempeh, due to enzymatic hydrolysis. These changes may account, in part, for an improvement in nutritional quality. For example, it has been suggested that protein hydrolysis makes tempeh more digestible, compared to...

Manufacture of fermented olives

There are three main styles or types of table olives, based on their method of production Figure 7-7 . Spanish-style or green Spanish-style olives are treated with sodium hydroxide lye and fermented. Greek-style or naturally-black, ripe-style olives are not treated with lye, but are fermented. The fermentation for both types is mediated by the natural microflora, much like that for other fermented vegetables discussed below .The third type of olive is the ripe black- or green-style. They are...

Defects

Among the microbial defects that occur in pickles, the most common are bloaters and floaters Table 7-4 .The defect is caused by excessive gas pressure that subsequently results in internal cavity formation within the pickles. The CO2 gas is mainly produced by heterofermentative lactic acid bacteria some of which may produce CO2 via the malolactic fermentation , although coliforms and yeasts may also be responsible. Floaters and bloaters can still be used for some processed products i.e., relish...

Lactose-6-phosphate

The phosphotransferase system PTS in Gram positive bacteria. As shown in panel A, the PTS cascade is initiated by the cytoplasmic proteins Enzyme I EI and HPr. Phosphorylated HPr HPr P then transfers the phosphoryl group obtained originally from PEP to the substrate-specific Enzyme II complex. The latter consists of several proteins or domains, shown here as EIIA, EIIB, and EIIC. However, depending on the organism and the substrate, EII complexes may be organized differently, for...

Wine Manufacture Principles

Making wine, as far as the actual steps are concerned, looks to be a rather simple and straightforward process Figure 10-3 . Grapes are harvested and crushed, the crushed material or juice is fermented by yeasts and bacteria, the organisms and insoluble materials are removed, and the wine is aged and bottled. In reality, the process is far from easy, and each of these pre-fermentation, fermentation, and post-fermentation steps must be carefully executed if high-quality wine is to be...

Nonalcoholic beer

Low- or non-alcoholic beers were first produced in the United States more than eighty years ago during Prohibition , and have been available ever since. However, the relatively low demand for these products did not drive the industry to devote very much research effort into new technologies. Due to a marked increase in the consumer demand for low- or non-alcohol products, the technology for making these beers has improved dramatically in the last decade.The quality of these beers, not...

Factors Affecting Yeast Metabolism

S. cerevisiae has the genetic capacity to metabolize sugars via either the glycolytic or respiratory i.e., TCA pathways. Although oxygen availability affects expression of genes encoding enzymes of these two pathways and is, therefore, an important determinant of which way metabolism will occur, gene expression is also regulated by substrate availability. Although one might expect that in the presence of oxygen, metabolism would always be via the respiratory pathway, this is not the case. If...

Lactococcus

The genus Lactococcus consists of five phylo-genetically-distinct species Lactococcus lactis, Lactococcus garviae, Lactococcus piscium, Lactococcus plantarum, and Lactococcus raf-finolactis Figure 2-3 .They are all non-motile, obligately homofermentative, facultative anaerobes, with an optimum growth temperature near 30 C. They have a distinctive microscopic morphology, usually appearing as cocci in pairs or short chains. One species in particular L. lactis, is among the most important of all...

Direct Lyophilized Milks Cultures

18,979,200 - 3.13 X 108 less than 1 xGiven the following assumptions Initial phage level 1 phage ml of milk Initial cell level 1,000,000 cells ml Phage latent period 40 minutes Cell generation time 40 minutes Average burst size 50 xGiven the following assumptions Initial phage level 1 phage ml of milk Initial cell level 1,000,000 cells ml Phage latent period 40 minutes Cell generation time 40 minutes Average burst size 50 In the past twenty years, however, the incidence of phage infections...

The Lactic Acid Bacteria

From the outset, it is important to recognize that the very term lactic acid bacteria has no official status in taxonomy and that it is really just a general term of convenience used to describe a group of functionally and genetically related bacteria. Still, the term carries rather significant meaning among microbiologists and others who study food fermentations, and, therefore, will be used freely in this text. Accordingly, the lactic acid bacteria are generally defined as a cluster of lactic...

Nh

Proteolysis during cheese ripening. The proteolytic system in lactococci starts with the hydrolysis of casein by a cell envelope-associated proteinase PrtP . The main products are oligopeptides, which are then transported across the cell membrane by the oligopeptide transport system Opp . Any free amino acids and di- and tripeptides in the milk are similarly transported by amino acid AA and di- and tripeptide transporters DtpT, DtpP , respectively. Once inside the cell, the...

Curd handling

Perhaps the most influential step during the cheese making process involves the means by which the curd is handled during and after the cooking and stirring steps. For many cheeses, the whey is removed when the desired acidity is reached, when the curd has been cooked for a sufficient length of time, or when it is sufficiently firm or dry. There are several means by which the curd is separated and the whey is removed. In traditional Cheddar cheese manufacture, the curds are simply pushed to the...

V

Formation of glycerol from glucose by Sac-charomyces cerevisiae. The glycolytic reactions from glucose to pyruvate are not shown. Once acetaldehyde is formed, end-products other than ethanol can be formed acetoin, acetate, and 2,3-butanediol . Over-expression of glycerol-3-phosphate dehydrogenase GPD results in glycerol production from dihydroxyacetone phosphate. Navratil, M., Z. Domeny, E. sturdik, D. smogrovicova, and P. Gemeiner. 2002. Production of non-alcoholic beer using free...

The Modern Beer Industry

Patent Pasteur 1873 Beer

Today, beer has one of the largest dollar values of all fermented food products, with U.S. retail sales in 2002 of more than 65 billion dollars. Box 9 1. Pasteur, the Origins of Microbiology, and Beer It is hard to imagine, given the current age of scientific specialization, that one person could have been as accomplished in so many fields as was Louis Pasteur in the latter half of the nineteenth century. He was trained as a chemist and, at the age of only 26, made important discoveries in...

Principles of Fermented Sausage Manufacture

There are actually only a few general steps involved in fermented sausage manufacture. First, the ingredients are selected, weighed, mixed, and stuffed into casings. Second, the stuffed sausages are held under conditions necessary to promote a fermentation. Third, the sausage is subjected to one or more postfermentation steps whose purpose is to affect flavor, texture, and preservation properties. These latter steps can range in duration from as little as one week in the case of moist or...

Strain improvement strategies

Since the beginning of beer making, all the way to the present, brewing strains have been used continuously, being passed down from batch to batch. These strains are highly adapted to wort and beer and are not very amenable to classical strain improvement strategies.That is, trying to select strains, either spontaneously or following mutagenesis, with improved fermentative, flavor-producing, or other relevant properties, is not an easy proposition. In addition, whereas laboratory strains are...

Recent Developments in the Beer Industry

The beer industry is one of the most competitive segments of the food and beverage indus-try.This competition has led to new technologies, new innovations, and new products. At the same time, there has been remarkable growth in the microbrewing industry, and a return to traditional or craft brewing practices. It is now possible to find nearly every type of beer at the local pub or retail outlet Box 9-8 . Thus, the beer industry, from the smallest to the largest brewer, continues to There are...

General Steps in Cheese Making

On a worldwide basis, there are probably thousands of different types of cheeses produced and consumed. As Charles De Gaulle, the former French president, famously lamented, there are hundreds of different cheeses made in France alone1. Anyone who has visited a fro-mageri in Paris or a formaggio in Milan or perhaps the National Cheese Emporium in England Box 5-3 , can certainly appreciate the incredible variety of cheeses that are available. How could there be so many Are the procedures for...

Proteolysis in cheese

It was long argued that milkfat was the primary constituent responsible for cheese flavor.While it is certainly true that many cheese flavors are either evolved from the lipid fraction or are soluble in the lipid phase, it is now generally accepted that, for most cheeses the main exception being the blue mold-type cheeses , it is the protein fraction that makes the more important overall contribution Table 5-2 . Cheeses made under controlled conditions in which proteoly-sis does not occur...

Flocculation

Flocculation Cells

Flocculation is the ability of yeast cells to agglomerate or adhere to one another in the form of clumps. When lager yeasts flocculate, the clumps have a density greater than that of the beer and settle to the bottom. Ale yeasts, in contrast, form clumps or flocs that entrap CO2 bubbles and have a lower density, and, therefore, rise to the surface. The ability of yeast cells to clump or flocculate, and the time at which flocculation occurs, are very important properties in beer manufacture. In...

Fermentors

The fermentation of the wort occurs in fer-mentor vessels of varying composition, size and configuration, and in either batch or continuous modes.Although most modern fermen-tors are now constructed of stainless steel, the traditional materials were wood, concrete, or copper. Size and shape depend on a number of considerations, but especially on whether the fermentation is top fermenting, as for ales, or bottom fermenting, as for lagers see below . For example, lager fermentation vessels are...

Propionic Acid In Hops

Proton Translocating Atpase

In the final step prior to fermentation, the wort is pumped into a special heating tank called the brew kettle. It is here that the wort is boiled and other important reactions occur.Be-fore the wort is heated, however, one more essential beer ingredient, hops, is added to the wort. Hops are derived from the plant Homu-lus lupulus in the family, Cannabinaceae , and although they were not part of the original beer formula, they have been added to beer since the Middle Ages. Why hops came to be...

Waste Management in the Brewing Industry

Although waste management affects all segments of the fermented foods industry, the issue is particularly important in the brewing in-dustry.This is because beer manufacturing uses nearly a half-billion tons of grains each year and, although some components of that grain are fermented, much of the grain is left behind. These spent grains represent a considerable disposal problem. Currently, this material is used in one of several ways. It can be further processed and used as a specialty food...

Measure pH

Lawrence. 1976.The selection of starter strains for cheesemaking. N.Z.J. Dairy Sci. Tech. 11 16-20. Hynd,J. 1976.The use of concentrated single strain cheese starters in Scotland.J. Soc. Dairy Technol. 29 3945. O'Toole, D.K. 2004.The origin of single strain starter culture usage for commercial Cheddar cheesemaking. Int. J. Dairy Technol. 57 53-55. Richardson, G.H., G.L. Hong, and C.A. Ernstrom. 1980. Defined single strains of lactic streptococci in bulk culture for Cheddar...