Cutting and Mixing

Once the ingredients have been collected and weighed, the process is remarkably simple (Figure 6-1). The meat portions (lean and fat) are usually ground separately in a silent cutter a rotating, bowl-shaped device that chops and mixes the sausage batter or a similar grinding device to produce varying degrees of coarse ness. The meat, along with all of the remaining ingredients, are then combined in a silent cutter. Mixing should be done to minimize or exclude oxygen, which not only can...

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...

Stuffing

After the batter has been sufficiently mixed, it is moved to a stuffer, a device that pumps the mix into casings. The casings are essentially long tubes that give the product its characteristic shape. The diameter of the casings can vary from less than 1.5 cm to more than 9 cm.As the tubes are filled, they are tied off or cut to give desired section lengths, again depending on the product being made. Lengths can vary from 5 cm to 100 cm. Shape and diameter size are important, not only because...

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...

Fermentation

According to traditional Indonesian manufacturing practices, the inoculated beans are then shaped into cakes and wrapped in banana leaves.The use of banana leaves as the packing chamber is not merely for natural aesthetics they provide a moist, microaerophilic environment that supports rapid growth of R. oligo-sporus. However, for large-scale manufacture of tempeh (and as conducted in the United States), the inoculated beans are distributed on trays 1 cm to 3 cm deep and ranging in length and...

Inoculation

After cooking, the beans are drained and dried. Next, they are inoculated with either a portion from a previous batch of fully developed tem-peh, a wild, mixed strain culture called usar, or, as is more common in modern manufacture, with a spore culture of Rhizopus micro-sporus var. oligosporus (hereafter referred to as R. oligosporus). Typical culture inocula levels range from 107 to 108 spores (about 1 g) per kg of beans. Pure R. oligosporus cultures can be added directly to the beans, or the...

Store at 4C or freeze

The de-hulled beans are then soaked in water, a seemingly simple step, but one which has very important implications for tempeh quality. It is during this steeping period (sixteen to twenty-four hours at warm ambient tempera ture), that endogenous lactic acid bacteria grow and produce acids that lower the pH.The low pH generally restricts growth of undesirable spoilage bacteria, as well as potential pathogens. It should be noted, however, that some of these undesirable bacteria can survive...

Substrate preparation

The process starts by sorting the soy beans to remove damaged or moldy beans (Figure 12-5). The beans are usually given a quick heat treatment (about 70 C to 100 C for ten to thirty minutes), and the hulls are removed either manually or mechanically.The former method, practiced by very small traditional manufacturers, involves rubbing the beans with hands (or even feet ) and then separating the hulls by floatation. Manual de-hulling, however, has been largely replaced by the use of various...

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....

Info

Adapted from Hachmeisterand Fung, 1993 and Winarno and Reddy, 1986 2Whole raw soybeans (prior to soaking) 3Fresh (wet) weight basis Adapted from Hachmeisterand Fung, 1993 and Winarno and Reddy, 1986 2Whole raw soybeans (prior to soaking) 3Fresh (wet) weight basis Most of the free fatty acids are subsequently oxidized by R. oligosporus, resulting in a 10 decrease in the total dry matter in the finished tempeh. In fact, the relative inability R. oligosporus to metabolize the available soy...

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

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...

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...

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....

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,...

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...

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...

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...

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...

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...

Cheese with Eyes

Swiss cheese, the most famous of the eye-containing cheeses, is considered by experienced cheese makers to be the easiest cheese to make but the hardest cheese to make well. This is because the manufacture of high quality Swiss cheese, and proper eye development, in particular, depends on two rather independent processes. First, Swiss cheese requires excellent curd handling technique, such that conditions are correct for eyes to form. Second, there must be precise control over the...

Streptococcus

The genus Streptococcus contains many diverse species with a wide array of habitats. Included in this genus are human and animal pathogens, oral commensals, intestinal commensals, and one and only one species, Streptococcus thermophilus, that is used in the manufacture of fermented foods. In general, streptococci are non-motile, facultative anaerobes, with an obligate homofermentative metabolism. Since the mid-1980s,there have been several major taxonomical revisions within this genus. Some of...

Beer Defects

Despite the low pH, high ethanol content, and hop antimicrobials ordinarily present in beer, microorganisms are responsible for many but certainly not all of the defects that occur in beer. Chemical and physical defects are also common and can cause significant problems for brewers. However, preventing or minimizing entry and growth of microbial contaminants throughout the beer-making process is absolutely essential for consistent manufacture of high quality beer. This is no simple matter,...

Ascospore

Ascospore Saccharomyces

Most lab strains form ascospores containing spores of opposite mating types, a and a. These spores can mate, hybridize, and form diploidal cells capable of budding or sporulating. In contrast, brewing yeasts generally only reproduce by budding. Figure 1. Yeast life cycle. Most lab strains form ascospores containing spores of opposite mating types, a and a. These spores can mate, hybridize, and form diploidal cells capable of budding or sporulating. In contrast,...

Cooking drying and smoking

Several different treatments and combinations of treatments can be applied at end of the fermentation. These include cooking, drying, and smoking. In the United States, fermented sausages are often cooked after fermentation, whereas, in Europe and elsewhere, raw sausages are the norm, and post-fermentation heating steps are rarely applied. In general, properly made dry, fermented, uncooked sausages, like salami and pepperoni, are still considered to be shelf-stable and ready-to-eat. Cooking,...

Fermentation and Metabolism Basics

Parts Aspergillus Sporangiospore

If one looks up fermentation in a biochemistry textbook, the definition that appears is usually something like this energy-yielding reactions in which an organic molecule is the electron acceptor . . . . Thus, in the lactic acid fermentation, pyruvic acid that is generated by the glycolytic pathway serves as the electron acceptor, forming lactic acid. Likewise, in the ethanolic pathway, acetaldehyde, formed by decarboxylation of pyruvate, is the electron recipient forming ethanol . So although...

Lactobacillus Casei

Lactobacillus Garicus

Although some strains of propionibacteria can ferment lactose, none is available during the time at which these bacteria are given the opportunity to grow i.e., several weeks after the primary lactose fermentation is complete . Instead, lactate is the only energy source available. Lactate fermentation occurs via the propionate pathway, which yields two moles of propionate, and one each of acetate and CO2 per three moles of lactate fermented. The cell nets one mole of ATP per...

Glucose6P

Trehalose metabolism by Saccharomyces cerevisiae. Structure of trehalose a-D-glucosyl-1 1-a-D-glucose is shown in the upper panel. Transport is mediated by a symport system, but synthesis from glucose-6-phosphate P may be the major route for trehalose accumulation lower panel . Trehalose not only alleviates stress, but it can also serve as a carbon source following its hydrolysis to glucose by the enzyme trehalase. of arginine and an increase in freeze tolerance and gassing power...

Preservation

Spoilage Bread Bacillus

Spoilage organisms of bread. Aspergillus niger Aspergillus glaucus Aspergillus flavus Penicillium sp. Rhizopus nigricans Mucor sp. Bacillus subtilus Bacillus licheniformis Bacillus mesentericus Given that biological spoilage of bread is caused primarily by molds, it is not surprising that preservation strategies have focused on controlling fungi, both in the production environment and in the finished product.As noted previously, mold and mold spores are present in flour and other raw...

Enzymatic Reactions Malting and Mashing

The first part of beer manufacture, the enzymatic steps, actually begins far from the brewing facility, in the malting houses that convert barley into malt. It is the malt that serves as the source of the amylases, proteinases, and other enzymes necessary for hydrolysis of large macromolecules, such as starch and protein. For most beers, the malt also serves as the substrates for those enzymes i.e., malt contains the starch and protein hydrolyzed by malt enzymes . In addition, malt is the...

H H pH C C C Hho

Structure of calcium propionate. How then, does calcium propionate exerts its anti-fungal activity Recall that weak organic acids can exist in either the acid undissociated or salt dissociated form Figure 2, upper panel . When the pH is equal to the pKa the dissociation constant of the acid, the concentration of undissociated and dissociated forms at equilibrium will be the same. When the pH is above the pKa, the equilibrium shifts to the salt or dissociated form. Conversely, when the...

End products

Although lactic acid is the major compound produced during the fermentation, other metabolic end products are also formed. Importantly, many of these products contribute to the overall flavor of sauerkraut. In particular, end products produced by Leuconostoc sp. and other heterofermentative lactic acid bacteria are essential for good-tasting sauerkraut.As much as 0.3 acetic acid and 0.5 ethanol can be present in the finished sauerkraut. In addition, these bacteria may also synthesize small...

Bluemold Ripened Cheese

Although blue mold-ripened cheeses are made throughout the world, three specific types have achieved a significant measure of fame to warrant their own name and have DPO status . Roquefort, perhaps the most well-known of all blue cheeses, must be made according to a strict set of manufacturing requirements. For example, the milk must come from specially-bred sheep that have grazed in the Causses region of France. It is neither pasteurized, standardized, nor homogenized, and the cheese must...

Yogurt Flavor and Texture

The most dominant flavor of yogurt is sourness, due to lactic acid produced by the starter culture. Most yogurts contain between 0.8 and 1.0 lactic acid and have a pH below 4.6. In the absence of sweetener or added flavors, most consumers can detect sourness when the pH is below 5.0. Other organic acids, including formic and acetic, may also be produced by the culture, but at much lower concentrations, and they generally make only modest contributions to yogurt flavor. There are, however, other...

Current Issues in Cheese Technology

Given the important role of microorganisms in the manufacture of cheese, it should come as no surprise that among the most important issues faced by the cheese industry, most are microbiological in nature not withstanding yield, costs, and other economic issues . The key to making any high quality fermented food, including cheese, is to control the activities of the microbial starter culture and other organisms.This means ensuring that they grow when they are supposed to, that agents that would...

Bread Consumption

Bread Consumption Worldwide

Worldwide consumption of bread per person per year . Adapted from Association Internationale de la Boulangeri Industrielle www.aibi-online.org and Federation of Bakers www.bakersfederation. org , 2001-2002 statistics. Figure 8-2. Worldwide consumption of bread per person per year . Adapted from Association Internationale de la Boulangeri Industrielle www.aibi-online.org and Federation of Bakers www.bakersfederation. org , 2001-2002 statistics. several thousands of years earlier. The...

Liquid sponge process

The traditional methods of bread making, as described above for the straight dough and sponge and dough methods, require sufficient time for the initial or bulk fermentation to occur and for the dough to develop. In the past several decades, an emphasis on speed and economy of scale has led to newer methods of bread manufacture.These methods rely less on bulk fermentation and natural dough development, and more on mechanical dough development and a relatively short fermentation period. The...

Biological spoilage

Mucoid Ropy Texture Breads

Microbiological spoilage of bread is most often associated with fungi, and occurs when fungal mycelia are visible to the consumer. Some strains of Bacillus subtilis, Bacillus mesenteri-cus, and Bacillus licheniformis can spoil high-moisture breads via production of an extracellular capsule material that gives the infected bread a mucoid or ropy texture.There are also wild yeasts capable of causing flavor defects in bread after baking however, bacterial and yeast spoilage of bread is relatively...

Heterofermentation

Heterofermentative lactic acid bacteria metabolize hexoses via the phosphoketolase pathway Figure 2-11 . In obligate heterofer-mentative bacteria, aldolase is absent, and instead the enzyme phosphoketolase is present. Approximately equimolar amounts of lactate, acetate, ethanol and CO2 are produced, along with only one mole of ATP per hexose. Oxidation of NADH and maintenance of the NADH NAD balance occurs via the two reductive reactions catalyzed by acetaldehyde dehydrogenase and alcohol...

Starter Cultures

The connection between wine fermentation and the development of the sugar fungus is not to be underestimated it is very probable that, by means of the development of the sugar fungus, fermentation is started. From A Preliminary Communication Concerning Experiments on Fermentation of Wine and Putrefaction by Theodor Schwann, 1837 as recounted by Barnett, 2003. The successful manufacture of all fermented products relies on the presence, growth, and metabolism of specific microorganisms. In...

The Modern Fermented Foods Industry

The fermented foods industry, like all other segments of the food processing industry, has changed dramatically in the past fifty years. Certainly, the average size of a typical production facility has increased several-fold, as has the rate at which raw materials are converted to finished product i.e., throughput . Although small, traditional-style facilities still exist, as is evident by the many microbreweries, small wineries, and artisanal-style bakery and cheese manufacturing operations,...

Sponge and dough process

The most commonly used method in the bread industry is the sponge and dough process. It is used by small, medium, and most large bakeries in the United States. The basic principle of this process relies on the use of a sponge, a partially concentrated portion of a flour-water dough that is allowed to ferment and then is mixed with the remaining dough ingredients. The main advantage of this method is it that it is tolerant to time. In other words, once the sponge is developed, it does not have...

Straight dough process

Bread Manufacturing

The homemade, one-batch-at-a-time method described above is generally referred to as the straight method or straight dough process. Basically, the overall procedure outlined in Figure 8-9 involves mixing all of the ingredients and then allowing the dough to ferment for several hours with intermittent punching down . The developed dough is then divided, formed into round balls, given a brief intermediate proof, shaped into loaves, and placed in baking pans. Finally, after a final fermentation or...

Defects and spoilage

Olives are, generally, more susceptible to microbial spoilage than other fermented vegetables. Initially there is a diverse microflora present in raw olives and that flora is well maintained during the early stages of the fermentation. Reflective of this heterogenous mix, spoilage organisms include aerobic bacteria and fungi, facultative bacteria and yeasts, strict anaerobes, as well as sporeforming bacteria. If the lactic fermentation is delayed due to residual lye or limiting glucose, or if...

Mozzarella and Pasta Filata Cheese

As a recently as a generation ago, Mozzarella was still considered a mostly ethnic cheese, used primarily as an ingredient in Italian cui-sine.The popularity of this cheese it is now equal to that of Cheddar cheese among American consumers Figure 5-3 , is due to one product pizza. Of the more than 1.2 billion Kg 2.7 billion pounds of Mozzarella and related cheeses consumed each year, about 70 is used by the food service industry as an ingredient on pizza. And while Cheddar production has grown...

Heterofermentative pathway

Mig1 And Saccharomyces

The Leloir pathway in lactic acid bacteria. surface and has substrate-binding activity. The energy released from ATP hydrolysis drives transport. In general, ABC systems are used to transport amino acids, peptides, and osmopro-tectants. However, several ABC systems are involved in sugar transport, including the maltose ABC systems in L. plantarum and the oligosaccharide-multiple sugar transport system in L. acidophilus. As noted above, regulation of sugar metabolism in lactic acid...

Ferment

Adapted from Cheigh, 1999. Box 7-2. Health Properties of Kimchi Continued kimchi can certainly be ascribed to the combination of these desirable sensory characteristics, there are also nutritional reasons that contribute to the its widespread consumption. For example, kimchi contains appreciable amounts of ascorbic acid vitamin C , B vitamins, calcium, iron, potassium, dietary fiber, and naturally occurring antioxidants. It is also important to note that kimchi is...

Microbial taxonomy and methods of analysis

If microbiology began with Pasteur in the middle of the nineteenth century,then for the next 120 years, microbial classification was based primarily on phenotypic characteristics. Although many of these traits remain useful as diagnostic tools, by far, the most powerful means of classifying microorganisms is now via molecular techniques. Originally, routine tests were based on nucleic acid composition mol G C and DNA-DNA and DNA-RNA hybridization.The latter has long been considered the gold...

Microbial Defects Preservation and Food Safety

Given that cheese is made in a mostly open, non-sterile environment, using non-sterile raw materials, and is exposed to or held at non-lethal, non-inhibitory temperatures, it is not surprising that all sorts of microorganisms can gain entry in cheese. Although the combined effects of moderately low pH, moderately high salt concentrations, and low Eh provide a barrier against some microorganisms, there are others, including spoilage organisms, and in rare cases, pathogens, that can grow in the...

Defects and Spoilage of Fermented Meats

Defects of fermented meats can occur before, during, or after manufacturing. Like all fermented foods, the production of high quality products depends largely on the microbiological quality of the raw ingredients. Perhaps this is even more so for fermented sausage, since the starting material, meat, is raw and cannot be heat-processed to inactivate spoilage or other undesirable microorganisms. Thus, any organisms present in the raw meat will be present in the sausage batter and may even survive...

Other Cultured Dairy Products

The emphasis of this chapter has been on those products produced and consumed in the United States. However, there are hundreds of other products produced around the world that, although manufactured via similar processes, have unique and interesting features Table 4-4 .Villi, for example, is widely consumed in Finland is known for its high viscosity and musty flavor and aroma.The ropy texture is due to capsular EPS production by L. lactis subsp. lactis and L. lactis subsp. cremoris, and the...

Economic value

Fermented foods were the original members of the value-added category. Milk is milk, but add some culture and manipulate the mixture just right, age it for a time, and the result may be a fine cheese that fetches a price well above the combined costs of the raw materials, labor, and other expenses. Grapes are grapes, but if grown, harvested, and crushed in a particular environment and at under precise conditions, and the juice is allowed to ferment and mature in an optimized manner, some...

Cultured Buttermilk

Buttermilk is the fluid remaining after cream is churned into butter. It is a thin, watery liquid that is rarely consumed as a fluid drink. Because it is rich in phospholipids derived from the rupture of milk fat globules during churning , it has excellent functional properties and is an especially good source of natural emulsi-fiers. It is typically spray dried and used as an ingredient in processed food products. Cul tured buttermilk, in contrast, is made from skim or low-fat milk that is...

Acetobacter Gluconobacter and Gluconoacetobacter

The only Gram negative bacteria used in the manufacture of fermented foods are the acetic acid-producing rods belonging to the genera Acetobacter, Gluconobacter, and Gluconoace-tobacter in the Proteobacteria phylum, Family Acetobacteraceae . These bacteria are obligate aerobes, with a respiratory-only metabolism. They make acetic acid via oxidation of ethanol some species may also have the capacity to further oxidize acetic acid completely to CO2 and water. The acetic acid bacteria are...

Protective Properties of Cultures

It has long been suggested that lactic acid starter cultures were responsible for preservation effects beyond their acidification and pH-lowering effects. During growth in meat, they scavenge sugars and other nutrients faster than competitors, and they lower the oxidation-reduction potential Eh of the environment such that growth of aerobic organisms is inhibited. In the 1980s it was discovered that some of the strains used as meat starter cultures may provide additional preservation effects...