During the Industrial Revolution, the development of hydrometers and thermometers allowed the brewer more control over the process and greater theoretical understanding of it. This marks the beginning of brewing science. One of the questions faced by natural scientists was the Aristotelian doctrine of “spontaneous generation,” or abiogenesis, which propounded that “life” was continually being created out of inanimate matter. The Italian physician Franceso Redi (1626-1679) around 1665, in a fine example of the proper use of the experimental method, placed clean linen cloths over jars containing fresh samples of meat. Flies, attracted to the meat, laid eggs on the cloth. Maggots could later be seen on the cloth, but not on the meat, which proved that maggots grow from eggs and do not develop spontaneously. Unfortunately, Redi failed to convince all of his contemporaries.

Since ancient times, observers had been fascinated with fermentation, which could transform grape juice into wine, but they failed to explain the process. It was the great Frenchman Antoine-Laurent Lavoisier in the 1780s who established the fact that organic compounds consist basically of carbon, hydrogen and oxygen. He did not fully understand the process of fermentation, but his work was a milestone in reaching a scientific understanding of the principles behind it. Another pioneering French chemist, Joseph Louis Gay-Lussac, proposed that fermentation was instigated by the action of oxygen on fermentable material. Huge advances were made during the nineteenth century, aided by improved microscopes.

Some of the best work to disprove spontaneous generation was carried out by the German scholar Theodor Schwann, a pioneer in cell theory in biology and medicine. He allowed air to pass freely over previously heated organic substrates (meat and hay infusions), but only after it had passed through very hot glass tubes. Such infusions failed to yield “life.” In 1837 Schwann demonstrated that alcoholic fermentation was the result of a living organism, not an inanimate chemical mass. He described the morphology of yeast, which he named “sugar fungus,” from which the generic name Saccharomyces emanates. There was nevertheless opposition to the idea of yeast as a living organism from many leading chemists such as the Swede Jöns Jacob Berzelius and the Germans Justus Liebig and Friedrich Wöhler.

In spite of this, by the mid-nineteenth century an increasing number of scholars believed that yeast was a living organism; even Berzelius had admitted as much by 1848. In the 1850s, H.G.F. Schröder (1810-1885) and T. von Dusch (1824-1890) conducted experiments in which they studied the role of air in decomposition. It was known (the principle was by then used for the preservation of food) that decomposition could in many cases be prevented by heating the material and excluding air from it.

The highly influential French scholar Louis Pasteur published work supporting the idea that yeast consists of living cells responsible for fermentation. By the 1870s most authorities had accepted his tenet that “there is no fermentation without life.” This applied not only to alcoholic fermentation, but to the myriad of other fermentations carried out by bacteria. Pasteur did more than any other person to establish acceptance for the germ theory of disease, which makes him a towering figure in the world history of medicine. In addition to pioneering medical advances such as discovering the first effective vaccine for rabies he worked with problems related to the wine industry, which in France is a matter of national pride. He studied bacteria in the microscope and identified which ones caused a particular wine disease. He demonstrated that these bacteria needed access to oxygen to live and reproduce. The most common is the vinegar bacterium, which is present in all wine and will eventually make it turn to vinegar (Old French for vin aigre, “sour wine”). Vinegar has been used since ancient times in Asian and European cuisines, but it was Pasteur who showed in 1864 that it results from a natural fermentation process.

For thousands of years, one of the challenges faced by all human cultures has been how to preserve food and prevent spoilage. A number of methods such as drying, salting and smoking have been employed. The canning of food was invented in the early 1800s by the French confectioner and brewer Nicolas Appert (1749-1841), prompted by Napoleon Bonaparte’s offer of 12,000 francs to the man who could invent a useful way of preserving food for his army. For years Appert experimented with various packaging techniques. He eventually found that food wouldn’t go “bad” if you placed it in champagne bottles, corked them loosely, immersed them in boiling water and hammered the corks tight. This practice preserved the food for extended periods, but the reason for this was still unknown. Later in the nineteenth century, tin cans made canned food available to urban populations throughout the Western world, especially when easy-to-use can openers had been developed by the early twentieth century. Cans are cheap and more resilient than fragile glass jars. Hornsey explains:

“Coincidentally, Appert was the son of an innkeeper, and also gained experience in brewing and pickling before becoming a chef and a confectioner. Gay-Lussac found that food treated by Appert’s method was quite stable, but as soon as it was exposed to air, fermentation and/or putrefaction set in. Further experiments enabled Gay-Lussac to prove that air was the causative agent, and that if liquid foods were actually boiled, and then exposed to air, then the onset of the two processes was delayed. He also found that if brewer’s yeast was heated, it was incapable of initiating fermentations. The proposition that yeast was a living organism, not a chemical compound, was not made until the mid- to late-1830s, when the results from three totally independent pieces of work appeared. It should be emphasised that these treatises coincided with the development of much-improved microscopes and, in order of publication date, the first to appear was the French mechanical engineer, Charles Cagniard-Latour, who, in 1835 (with additions in 1837), microscopically monitored the changes that yeast underwent over a period of fermentation.”

Louis Pasteur knew of Appert’s work, but his careful scientific methods succeeded in convincing the skeptics. Pasteur had developed an interest for chemistry and biology and focused on the souring of milk and the fermentation of sugar to alcohol. In the 1860s he developed a method, now known as pasteurization, which uses the application of heat to destroy human pathogens in foods. Appert’s method of cooking the food to a temperature far in excess of what is used in pasteurization (typically around 60-70 °C, but this varies according to the product) can destroy some of the flavor. Pasteurization does not intend to kill all microorganisms, only to reduce their number to prevent them from causing diseases.

Complete sterilization has negative effects on the taste of the food. The optimal temperatures for the preservation of various foods with minimal damage to flavor were worked out by two scientists at the Massachusetts Institute of Technology (MIT) in the USA, Samuel Prescott (1872-1962) and William Lyman Underwood (1864-1929) in 1895-96. Their work represented a milestone in the development of food technology and food science.

Several sources I have seen, including Ian Hornsey in his A History of Beer and Brewing, claim that something that could be compared to pasteurization was employed in China and Japan before Pasteur, but even if this should be true the process was not fully developed or understood there. It could not be so until the invention of high-quality microscopes in nineteenth century Europe. Pasteur explained why the process worked, which is why it should properly be named after him. The distinction is not trivial; the establishment of microbiology created modern medicine as we know it, and this development did not take place in East Asia.

Emil Christian Hansen (1842-1909), a mycologist and fermentation physiologist from Denmark, was the first brewery scientist to culture and describe brewery yeasts. His work commenced in 1879 after he was appointed to the Carlsberg Laboratories in Copenhagen. A lot of his early work involved the study of diseases affecting beer production, just as Pasteur and others had done for the wine industry. Hansen worked out a method of isolating a single cell from a culture of yeast. In 1883 he had achieved the isolation of the world’s first single-cell culture and introduced pure-culture methods into the Carlsberg brewery. It became known as Saccharomyces carlsbergensis and is used industrially in the production of lager beers.

Lager-brewing seems to have originated in southern Germany, where beer has been made since late medieval times by a bottom-fermentation process where the yeast sinks to the bottom of the brewing vessel; before that, the type of yeast used tended to rise to the top of the fermenting product. Such beers came to be called lager (from German lagern, “to store”). The first lagers in Bavaria were dark brown in color, and the dark version is known as a Munich-style lager. “Lager” refers to yeast that requires a slow fermentation and has nothing to do with color.

The archetypal pale, bottom-fermented lager which most consumers will be familiar with today was first brewed in 1842 in a city called Pilsen, or Plzen, in western Bohemia in what is now the Czech Republic. Local brewers there suffered from stiff competition from imported Bavarian beer but enjoyed some natural advantages; the water in the vicinity was extremely soft with minimal amounts of dissolved solids, which permitted the brewing of very pale, delicately-flavored beers. Bohemia has ancient brewing traditions and grows wonderful hops, whereas neighboring Moravia has plenty of great barley. Bohemians were also fairly well abreast of technological developments. Carl Balling, a professor of chemistry at the Polytechnic Institute in Prague, lectured about the living nature of yeast as early as the 1840s.

Josef Groll (1813-1887), a Bavarian brewer, created the world’s first clear, golden lager beer in Pilsen in 1842. He ended up with an extremely pale drink compared to the dark Munich lagers he knew. As the innovation grew in popularity, the people of Pilsen in 1898 renamed their beloved beer Pilsner Urquell (Plzeňský Prazdroj in Czech), which means “The pilsner from the original source” in German. This is the original pilsner beer, copied by breweries around the world. Its golden color was a novelty at a time when glass vessels were gradually replacing earthenware vessels. The Romans had sometimes used drinking vessels (but not bottles) made of glass which displayed the color of their beloved wines. The Roman glassmaking traditions continued in medieval Italy as well as in other parts of Europe. Authors Alan Macfarlane and Gerry Martin tell the tale in their cultural history of glass:

“Glass making was well developed in Germany and France at the end of the Roman Empire and this tradition continued, finding its highest development in Bohemia. Recent developments in medieval archaeology have now allowed us to see that fine glass was not an Italian preserve. There were, in fact, two different glass-making traditions in Europe. That in the north, in Germany, France, Flanders, Britain and Bohemia, was, certainly until the early fifteenth century, just as sophisticated as that in Italy, even if it used different techniques and produced other styles of glassware. In Bohemia, the wealth created by the silver mines brought the prosperity that enabled people to buy the exceptionally fine, colourless and thin glass, which was being made there by the fourteenth century. This was the continuation of an earlier tradition and in due course the Bohemians would even outdo the Italians.”

The new beer quickly established a fervent following for itself, and thanks to a well-developed transport system which included railways and canals, supplies could be made available to all major towns within the Austro-Hungarian Empire and beyond. At one stage a train laden with this new beer left Pilsen every morning with supplies for the imperial capital of Vienna. Nevertheless, it took years for the new, pale lager style to be copied by Bavarian brewers following rising popular demand.

Spaten Brewery in Munich launched a pale lager in 1894. Their brewer at that time was Carl Sedlmayr, son of the renowned brewmaster Gabriel Sedlmayr Jr. who was an advocate of the use of the steam engine in the brewery. Along with the Austrian brewer Anton Dreher he had toured dynamic England and Scotland in 1833 and managed to gain access to a few breweries. The visitors were fascinated by the industrial methods they observed and the fact that British brewers could produce beers of consistent strength, achieved with the aid of the saccharometer. Dreher’s Schwechater Brewery in Vienna became the first to brew bottom-fermented Vienna-style lager in 1841, which soon proved very popular.

The innovation spread until pilsner became the most common form of beer consumed in the world. It reached the USA and Canada as well as Australia in the late nineteenth century via German-speaking immigrants, at a time when ice-making machines were beginning to be a part of general brewing equipment. Pale-colored bottom-fermented lagers made by pure yeast cultures soon predominated in New World brewing, including American Budweiser which by 2009 is the world's highest volume selling beer.

In southern Bohemia lies the city of Budweis, which competes with Pilsen for being the center of Czech brewing. Beers from this town come under the generic name of “Budweisers.” Such was the fame of these beers that American brewers used the name Budweiser for one of their beers when they opened a brewery in Missouri in 1875. This clash of names has resulted in endless legal battles between the American company and its Czech rivals.

In the history of wine, the late seventeenth century was a great turning point due to the introduction of corked glass bottles for transporting and selling wines. This made it possible to store wines for many years and let them mature, which for some though not all wines can improve their taste. This revolution affected the world of beer, too. Ian Hornsey explains:

“It was during the 17^th century, we believe, that the first glass beer bottles were used. Before that, leather, earthenware and stoneware were the favoured materials. For almost two hundred years, beer in a glass bottle was a ‘boutique’ drink, and it was not until the 1860s, with the invention of the chilled iron mould, that glass bottles could be relatively cheaply mass-produced. Prior to this, bottles were hand-blown, and thus expensive. A major development in glass bottle manufacture was the American Owens bottle-making machine, of 1898, which was the first source of cheap, mass-produced glass bottles. In the early years of the 18^th century, Bristol was an important centre for glass manufacture, and large quantities of bottles were exported to America and Ireland. Instead of going out empty, they went full of beer, and the longevity of the bottled product, as opposed to cask beer, was quite noticeable, especially on the journeys across the Atlantic.”

Needless to say, this industrial mass production of glass bottles affected numerous other products in addition to wine and beer, for instance jam or milk. Aluminum beverage cans for beer or soft drinks had their breakthrough in the second half of the twentieth century. Being lighter and non-breakable, cans had many advantages over glass bottles, and containers protect their contents from light. Modern breweries today use stainless-steel equipment, automated operations controlled by electronic computers and package beer in aluminum cans and plastic containers. Brewing has become a huge global industry. In any decent bar you can buy bottles of export-beers from many different countries. As a response to brewing on the very large scale, smaller breweries and “microbreweries” have become more abundant from the 1980s onward. These smaller breweries can often make beers with more distinct flavors.

In his Great Beer Guide, beer writer Michael Jackson lists some of his favorite beers. One of them is the Guinness Extra Stout from Ireland: “The world’s most famous dry stout. Arthur Guinness was a county brewer in Ireland before setting up in Dublin in 1759. It was originally an ale brewery, but began to make porter in the 1770s. During World War I, fuel restrictions made it difficult for British maltsters to roast their grains, but this was still permitted in Ireland. ‘Plain Porter’ was dropped in the 1970s and, despite a brief revival of that style in the 1990s, Guinness is best known in both Ireland and Britain for its Extra Stout.”

In the Netherlands, Heineken is the most internationally famous brand. It traces its history to a brewery in Amsterdam from 1592, but the first Heineken became involved with the brewery in 1864, at which time white beer and porter were being produced there. Lager brewing of dark brown beers began in 1869 and today’s yeast culture was introduced in 1886. Among other Dutch brands, Grolsch is easily recognizable with its distinctive swing-top bottle.

Wine usually has a higher alcohol concentration than beer. Whereas the average beer normally contains 4-5 percent alcohol, the so-called barley wines contain 8 percent or more. Some very fine strong beers are made in Belgium. The Trappist beers, produced by a strict order of monks in several Belgian monasteries, are highly regarded by connoisseurs. Chimay is perhaps the best-known of the Trappist abbey breweries. Another brand is Orval. As Jackson says, “The abbey’s name derives from Vallée d’Or (Valley of Gold). Legend has it that a countess lost a gold ring in a lake there, and vowed that she would establish a monastery it if were ever returned. A trout appeared from the waters with her gold ring in its mouth, and she was as good as her word. Monks have occupied the site, in the Ardennes, since 1070. Today’s 1930’s abbey is an architectural gem, and the beer a classic.”

Rodenbach Grand Cru is a Flemish Red Ale that is extremely tasty, but as many highly distinct beers it enjoys small sales compared to mainstream beers like Carlsberg or Heineken. Jackson is a fan of Belgian beers. According to Michael Jackson's Great Beer Guide:

“Light-tasting lagers will quench the thirst, but wheat beers do the job much better, whether the Belgian style like Hoegaarden or the German Weisse/Weizen types. The most refreshing beers of all, after the first shock of their sour tinge, are Belgian ‘red’ ales such as Rodenbach. In the same mood, a fruit beer can be an attractive drink with which to greet guests at a barbecue or party. If people went to the pub simply to quench their thirsts, they would probably have one pint, then leave refreshed. Most beer-lovers prefer to stay longer than that. One pint of cold, fizzy lager might be quenching, but more can become bloating. The colder the beer, the more its carbonation is released in the warmth of the stomach, with uncomfortable effects. An hour or two in a good pub offers sociability. The most social beers are less cold and gassy, softer, and appetizing, like English bitter, an ale from Belgium, or a German Altbier or Kölsch. It has been argued that all beers are sociable, but [they] must be modest in alcohol. It is excessively modest to fall asleep, or worse, in the pub, and immodest to be roused by alcohol to aggression.”

The dominant ingredient used for brewing in East Asia throughout most of recorded history has been rice. Whether such fermented beverages should be classified as “rice beers” or “rice wines” (the latter being the most common designation) is debatable. Japanese sake is closely related to Chinese rice wine. A number of Asian countries produce a few beverages similar to Western beers, usually as a result of direct exposure to German, Dutch, British or other European brewing traditions. These include brands such as Singha in Thailand or Tsingtao in China, a pilsner-style beer and the only Chinese beer widely known outside its home country. In the early 1900s, Tsingtao was a German port the way Hong Kong was British and Macao Portuguese. Germans initially founded the brewery, but it is currently Chinese-owned.

In Japan, locally made European-style brews joined sake and related Asian beverages after the Meiji Restoration in the late nineteenth century. The brewery in Sapporo opened in 1876 and claims to be “Japan’s oldest brand.” It can now boast of having brewed the world’s first “space beer.” This happened in 2008 after a five-month mission during which barley was grown for the first time in a Russian laboratory on board the International Space Station (ISS). Sapporo Breweries used the crop of this barley grown in space to create 100 liters of Space Barley. The beer was brewed as part of joint research conducted with Okayama University.