Tuesday, December 12, 2017

Food Science: Beer

I'm working on a MOOC for WUR about Beer. There are several portions, but I'd like to post the two sections I'm working on: Culture and History and Cultivation Methodology (Storage, Preservation, Transportation). These are rough drafts, but it might be interesting to someone.




Video 1:



The History of Beer 1

It’s 3000 BC. You’re sitting around the fire after a long day of farming. There’s a goat roasting over the flames and yams baking in the coals, but what do you have to drink?

Mostly it’s water and if you’re lucky it hasn’t been contaminated by human or animal waste. If you’re not…well, you’ll be dead in a few hours. So what do you do?

Well, archaeologist Patrick McGovern, from the University of Pennsylvania, may have a clue. He has identified the oldest known barley beer, which he says came out of Iran around 3400 B.C., and the earliest known alcohol of any kind, a Neolithic grog from China’s Yellow River Valley brewed almost 9,000 years ago. What we would consider ‘modern’ beer shows up around 5,000 years ago in Neolithic Europe.

The modern word for beer can be traced back to the Arabic and Persian words ‘boza’ or ‘bizr’. In the 11th century, Mahmud of Kashgar, on China’s far western border, writes of a number of grain-based foods and drinks including aghartghu, a ‘wheat beer’, and begni/bekni, a ‘drink of wheat, millet, and barley’. These terms were still in use through the 15th century in Mongolia, showing how popular the drink was.

Beer, which at its core is just a fermented cereal plus water, was typically made at home, by women as a by-product of the bread making process.

The malt used in modern beers was originally made from what’s commonly referred to as beer bread. This bread was actually barley, or possibly emmer, an ancient grain, that had been allowed to germinate, and then was dried out and eventually formed into small, lightly baked loaves. When beer needed to be made, these loaves were crumbled into water with other cereals and allowed to ferment.

Historically speaking, water wasn’t always the purest beverage, as many homes and cities put their waste right back into their source of drinking water. The process of fermenting and heating the beverage made the alcohol safer.

Eventually, brewers in the Middle East passed along their recipes to the Greeks and Romans, but their climate was better suited to wine production so beer was never created in masse. After the fall of the Roman Empire, brewing continued as a predominantly household task.

Brewing was so popular it was even encouraged by the Catholic Church, who promoted all monasteries and nunneries to brew their own beer for weary travelers who might stop by or for the village they served. The better the beer, the more tithing’s the Church could potentially receive. They also worked to advance cleanliness as a necessity for preparing good beer and to generally improve the brewing process.

A few hundred years later, in 1200 AD, Beer production became a major industry and could be found in countries such as Austria, Germany, and England. In Germany we can still find one of the oldest breweries that are still in operation. Its production started in 1040 AD and it’s the Bayerische Staatsbrauerei Weihenstephan in Freising.

While the German's preferred cold temperature lagers processed by bottom-fermentation, which they stored in caves in the Alps, the English preferred mild temperature ales processed by top-fermentation, which were stored in cellars.

The difference in production methods was due mainly to weather. You see, traditional beers of the time were ales. The ale’s warm and turbulent “top fermentation” carried the yeast to the foam on top of the beer where it often formed a thick mat and was harvested and used to start the next batch.

Brewers in Bavaria, however, found it advantageous to attempt fermentation and storage in cool caves at the foothills of the Alps, where it was possible to ferment beer even in summertime. The term “bottom fermentation” was first used here, in Bavaria in 1420.

Until this development, warm weather meant that brewing had to stop because dangerous spoilage bacteria would often kill the yeast and make the drink unsafe.

The yeast that developed in the caves fermented slower and less vigorously than ale yeast. It never formed much foam on the surface and, when finished, sunk quickly to the bottom of the vessel. From there it was collected and used in the next batch of beer. Over time, selection of yeast from the bottom of the vessel naturally favored yeast types that precipitated well, and these became known as “bottom-fermenting” yeasts.

This type of cold-fermenting yeast was finally isolated in a pure culture by Dr. Emil Christian Hansen, over 400 years later, in 1883 and was named Saccharomyces carlsbergensis, after the lab it was created in.

Join us next time as we take a look at how Beer cleaned up its act and how it’s grown in more modern times.

Video 2:


The History of Beer 2

Welcome back. Last time we learned about the earliest beer, why people felt the need to drink it over water, and the differences in brewing methods based on a culture’s geography. Today we’ll dive a bit deeper and look at the laws, cultural aspects, and future of beer.

While different cultures crafted beer in various ways, certain key features of beer production were underway, including ‘standards’ which needed to be met by most societies.

The Babylonian King Hammurabi, nearly 4000 years ago, forbade brewers from diluting their beer and also put a ceiling on the price they could charge for it.

Of course, the Egyptians and Babylonians actually drank their beer through a straw because it was so thick with pieces of grain, which might explain all their rules.

By the 16th Century, Germany’s “Reinheitsgebot” (Rein-Hets-Ga-Bot) or Beer Purity Law, had essentially removed everything but water, hops, and barley from acceptable brewing ingredients. Yeast was added to the list a few centuries later thanks to Microbiologist Louis Pasteur, who discovered the fermentation process in 1857.

By the 1700s, beer was considered the common-man’s drink in Europe, but it was gaining stiff competition from the New World.

In 1777, Frederick the Great, King of Prussia, annoyed with the great sums of money going to foreign coffee merchants in Sweden, Prussia, and Hanover, issued an edict against coffee that espoused the greatness of beer.

“My people must drink beer,” he says. “His Majesty was brought up on beer, and so were his officers. Many battles have been fought and won by soldiers nourished on beer”. Coffee persisted, but so did beer.

In the 1800s, farm owners in the United Kingdom were encouraged to pay their laborers in food and lodging, including beer. Pamela Sambrook, in her book, Country House Brewing in England, explains that in 1829, a farm laborer could expect between 5-12 pints of beer based upon their work load. The benefit was that beer was a ‘safe’ beverage and an easy way to get the sugars, calories, and vitamins needed for heavy labor. A generation later in 1851, Henry Stephens’ widely popular The Book of the Farm espouses using the same tactics to minimize payment in hard currency.

Hop across the pond, and we see an explosion in the commercial brewing industry in the late 1800s in the United States. The advent of commercial refrigeration in 1860, automatic bottling and pasteurization in 1876, and mass railroad distribution allowed for beer to become safe, affordable, and most importantly, accessible to most Americans.

Unfortunately, times change. The beginning of the 20th century saw a drastic reduction in breweries in the United States. Between 1920 and 1935, a combination of the Prohibition Act and company mergers, saw beer manufacturing houses drop to just 160 breweries.

To give an idea of the decline, in the mid-1870s, the U.S. population was roughly 45 million and the number of breweries per population was about one brewery for every 11,000 people. That gives us almost 4,000 breweries.

Since then beer has made a dramatic comeback, with more than 5,000 breweries in the U.S. alone; over 3,000 of which are considered craft or microbreweries.

Perhaps Shakespeare should have quipped, “To drink, or not to drink,” for it appears that for close to 9,000 years humans have found ingenious ways to ferment cereal crops into nutritious alcoholic beverages.

Once the domain of monks and women and the staple of many a laborers’ diet; the beer industry has definitely grown-up over the last few centuries. You can almost say, it seems to have matured and can now specialize in its craft.

I hope you’ve enjoyed this trip through time as we learned about the birth and growth of beer and the industry around it. Join us as we dig deeper into the Science of Beer over the next few modules.



Prost!

Sources

A brief history of beer. (2017). Retrieved from Vinepar: https://vinepair.com/beer-101/a-brief-history-of-beer/
Barnett, J. A. (2005, June 15). A history of research on yeasts 2: Louis Pasteur and his contemporaries, 1850–1880. Yeast, 16(8), 755–771. doi:10.1002/1097-0061(20000615)16:8<755::AID-YEA587>3.0.CO;2-4
Dictionary, O. C. (2017). Bottom Fermentation. Retrieved from The Craft Beer and Brewing Magazine: https://beerandbrewing.com/dictionary/2Kudv5620R/bottom-fermentation/
Kiefer, D. M. (2001, December). Brewing: A legacy of ancient times. (A. C. Society, Ed.) Today's Chemist at Work. Retrieved from http://pubs.acs.org/subscribe/archive/tcaw/10/i12/html/12chemchron.html
Perry, C. (1983). Grain Foods of the Early Turks. In Food in Motion, the Migration of Foodstuffs and Cookery Techniques (pp. 11-22). London: Oxford Symposium.
Roden, C. (1983). The Spread of Kebabs and Coffee: Two Islamic Movements? In Food in Moton, the Migration of Foodstuffs and Cookery Techniques (pp. 74-79). London: Oxford Symposium.
Sambrook, P. (1996). Country House Brewing in England, 1500-1900. London: Bloomsbury Academic.
Stephens, H. (1851). Book of the Farm (Second ed., Vol. Two). Edinburgh: William Blackwood and Sons.
Tucker, A. (2011, August). The Beer Archaeologist. Retrieved from Smithsonian Magazine: https://www.smithsonianmag.com/history/the-beer-archaeologist-17016372/
Tuttle, B. (2016, December 9). America Now Has a Record-High 5,000 Breweries and Counting. Retrieved from Time: http://time.com/money/4596638/america-record-high-craft-breweries/

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Storage, Preservation, and Transport of Beer and its Constituent Ingredients

Grains

The methods for storing, preserving and transporting cereal crops haven’t changed in the last few hundred years. The basics of having the grains as dry as possible and their storage containers as clean as possible are still the two primary tenets of proper storage; damp or dirty conditions leads to mold and pest infiltration, both of which can make the grains unsuitable for human consumption. It is recommended that wheat should have less than 14% moisture for 9 months storage and less than 13% moisture for more than 9 months storage. Barley should be about 13.5% or 12.5% respectively. Many extension services recommend spraying an insecticide if grain is to be stored for longer than 9 months. This has an obvious health concern, although no literature was found on the subject at the time of this module.

When loading the bins the grains are stored in, fine material will tend to form in pockets, the problem is that fine material restricts airflow and is more susceptible to attack by molds and insects. The use of a grain spreader to fill bins and distribute fines uniformly throughout the grain mass is the easiest way to fix this issue. Keeping grain cool reduces mold and insect activity. Activity slows at temperatures below 60° F and almost ceases below 40° F. Because daytime temperatures are usually greater than 60° F in late summer and early fall, operating fans at night may help the cooling process. There is some debate about freezing grain and then defrosting it, however, this has shown an increase in moisture trapped between the grain kernels and is generally not recommended.

Uncrushed grains are relatively stable and can be stored for a year or more if kept cool, free of moisture, away from light and free of bugs. Crushed grains do not store as well largely due to exposure of the interior of the grains to oxygen. In general, try to use crushed grains within a few weeks, but some sources say they can last as long as 2-3 months if properly stored.

Malt

In making malt, barley is steeped in water until it reaches high moisture content. The barley is then germinated. This sprouting results in activation of enzymes which break down starch in the grain releasing sugars which are the foundation of the malt. Skinned kernels or kernels with damaged husks germinate with exposed sprouts which are easily broken off when the barley is stirred during malting. If the unprotected sprout is broken off, germination is interrupted and the kernel is not completely malted. Skinned kernels are also more susceptible to mold growth than kernels which are protected by the husk and produce an inferior tasting product.

Dry malt extract should be stored in a dark, cool area, ideally in an oxygen barrier bag as heat and light are bad for malt extract - they both darken and break down the extract over time. A good place to store dry extract is in the refrigerator. Another option is liquid malt extract, which comes in cans and is primarily at risk from heat, so keep it in a cool location or refrigerate it. Properly stored it can be used for a year or more. Open syrup or syrup sold in plastic containers has a much shorter shelf life as it is at risk of both infection and oxygen.

Hops

Hops are even more susceptible than grains to heat, oxygen, light and moisture. They are best stored in a freezer in an oxygen barrier bag such as a foil bag or glass jar. As they age they will lose bittering power as well as aromatic oils, eventually imparting a distinctive stale flavor. The rate at which hops age depends on both the type of hops, their Hop Stability Index, and their storage conditions. Some varieties will last only a few months while others can be kept for nearly a year if properly stored.

Yeast

Dry yeast is easy to store and has a long shelf life. If kept sealed in its pouch at room temperature, it can easily last 1-2 years. You can also refrigerate it, but don’t freeze it, to extend its life even further. Liquid yeast, however, has a relatively short shelf life and lose about 20% of their viability each month, which gives you a max of 6 months to use it, and they must be refrigerated.

Beer

There are four rules for beer preservation: light, temperature, bottle position and picking the right beer.

Like the ingredients that go into beer, you want to store your beer in a dark, dry place. Dark or brown bottles protect beer, shielding it from damaging UV light. If you have a green or clear glass bottle, its meant to be drunk quickly and not stored. A temperature controlled fridge will help you make the most out of storing beer, but a basement or cellar somewhere between 15°C and 23°C (59°F and 74°F) will work just fine. Ironically, there is a bit of argument over if bottles should be left standing upright or turned on their side. Basically, if you have a metal cap, let it stand. This will keep rust on the cap at a minimum. If the beer is corked, lay it on the side. A moist cork is one with a good seal and will prevent air bubbles.

Of course, if you pick a beer that has been pasteurized, as many microbreweries do, this won’t help you. Pasteurization, by design, kills bacteria, which is what the yeast that gives beer its taste is. Therefore, it’s useless to store most macro-brewery beers as their fermentation will barely continue and the taste will mainly degrade.

When choosing appropriate beers, you can generally trust such styles as witbiers, doubles, triples, quadruples, abbey, trappists, weizens, bocks, doppelbocks, Belgian strong ales, gueuzes, lambics, bieres de garde, etc.

You will find that some beers stop evolving after a certain period of time. Witbiers and Weizens are generally best after 6 months (no longer). This is normal and a great excuse to pop open a bottle to enjoy.

Resources:

http://www.madehow.com/Volume-2/Beer.html
http://ambainc.org/media/AMBA_PDFs/Pubs/Harvesting_Drying_and_Storing_Barley.pdf
https://www.extension.umn.edu/agriculture/small-grains/harvest/wheat-and-barley-storage/
http://beersmith.com/blog/2016/06/16/storing-and-preserving-your-beer-ingredients/
http://www.beertutor.com/articles/storing.shtml
https://dspace.library.colostate.edu/bitstream/handle/10217/182929/AEXT_ucsu2062201171998.pdf?sequence=1

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