Production of Beer

From barley to beer the production of beer is known as Brewing.

There are top-fermented beer and bottom-fermented beer.

Top fermented beer - also known as ale, are prepared with Saccharomyces cerevisiae, top-fermenting is the oldest method and the yeast used for it. The yeast is applied to the top of the wort, and at a higher temperature.

Bottom fermented beer - are known as lager beer is bottom-fermented, meaning the yeast works at the bottom of the wort, at a much lower temperature. And that’s because the yeast involved in bottom-fermenting is a hybrid of Saccharomyces cerevisiae and yeast called Saccharomyces eubayanus, wild yeast from Patagonia that likely hitched a ride to Europe on an exchange transport a couple of hundreds of years prior. In contrast to S. cerevisiae, S. eubayanus can flourish in a lot colder temperatures—and their infant yeast, S. pastorianus, acquired that capacity (thanks mother!).

RAW MATERIALS FOR BREWING-

CEREAL GRAINS ( usually barley, corn, or rice)
ADJUNCTS - Starchy material that is added to with the intention of cutting costs, but sometimes also to create an additional feature, such as better foam retention, flavors, or nutritional value or additives. Both solid and liquid adjuncts are commonly used.
YEAST CULTURE
HOPS - the cone-shaped flowers of the female hops plant, aka Humulus lupulus. The addition of hops has several effects like - it provides bitterness, it provides pleasantly aroma, provides colloidal stability & foam head retention of a beer, also contains tannins that help precipitate protein during the boiling of wort, and if the protein is not removed then it causes a haze in the beer at low temperature.
WATER - mineral, pH, ions - It affects the pH of the beer, which affects how the beer flavors are expressed to your palate; it provides “seasoning” from the sulfate-to-chloride ratio, and it can cause off-flavors from chlorine or contaminants.

Different steps of the brewing process -

Malting -

It is done to double up the amylase and proteases in barley grain, these enzymes reproduce in germinated barley that enables it to breakdown carbohydrates and proteins in the grain. In this process grain is cleaned, steeped, or soaked in cold water is done at 10-15 °C for 2-3 days. Then it is drained off and transfer to the malting floor then germination takes place. Sometimes moist warm air is blown through the bed of seedling and water is sprinkled. Gibberellic acid is added to the grain, it is a hormone and fasten up germination. This process is known as malting.

Cleaning and milling of malt -

Malt is clean and passed over the magnet to remove pieces of the metals, it is milled and this milling is done to expose particles of malt to the hydraulic malt enzyme in the further mashing process.

Mashing -

This is the central part of brewing done to extract a soluble portion of malt and to enzymatically hydrolyzed the insoluble portion of malt. The malt is crushed using iron rollers and transferred to the mash tank (or "tun"). This tank is a large copper or stainless steel vessel that mixes the malt with warm water until it is of porridge-like consistency. This mixture is called mash. After mixing with similarly prepared cereal grains, the temperature of the mash is raised incrementally from 100-170°F (38-77°C) so that the enzymes react. The enzymes break down the starch in the grain and convert it to simple sugars. Later, the yeast will convert the sugars into alcohol. Once complete, the mash is allowed to sit undisturbed so the solids can descend to the bottom of the tank.

The aqueous solution resulting from the mashing process is known as Wort (liquid part).

Mashing is affected by the combination of temperature, pH, and concentration of wort. If the temperature is between 60-65°C for a longer period then maltose occurs much because the β- amylase activity increase, if the temperature is 70°C for a longer period then dextrin increases which are not utilized by yeast. There are two enzymes involve α- amylase (70°C and ph 5.8) whereas β- amylase (65°C and pH 5.4), proteases (60°C and pH 5.2-5.5).

Mash Separation -

At the end of the mashing husk and insoluble material are removed from the wort in two steps-

Wort is separated from solid.
Solids are freed from extractable material while washing or sponging with hot water (80°C) and the leftover malt and adjuncts after the mash has extracted are known as spent grain.

Wort Boiling -

The wort is boiled for one and a half hours in a brew kettle made up of copper or stainless steel. Sometimes adjuncts are also added, corn syrup, sucrose is added initially in the boiling. Hops are also added before and some at the end of the boiling. The main purpose is to -

Concentrate the wort
To sterilize
to inactivate any enzyme
to precipitate complex with tannins
to develop color
to remove volatile compounds like fatty acids.

Pre fermentation of wort

In this process, derived hops are used is removed in hop strained and during the boiling protein and tannins are precipitate and more precipitating takes place when it is cooled about 50°C.

Precipitate removed by centrifugation. Separated wort is then cooled in a heat exchanger when the temperature is fallen below 50°C further sludge begins to settle called a cold break.

Wort is filtered with kieselgur (diatomaceous earth).

Further, cooled wort is ready for fermentation, during transferring wort, the wort is oxygenated to provide the yeast with oxygen for initial growth.

Fermentation

There are top and bottom fermentation

In top fermentation -

Saccharomyces cerevisiae, temperature 15-16°C at the time of pitching - inoculation pf yeast is done in the wort. the temperature is raised around 20°C in 3 days entire fermentation time is around 6 days. Yeast flows on top i.e. scooped off and can be used for further pitching.

In bottom fermentation -

S. uvarum or S. eubayanus used in this process for 12 days, in this process yeast begin to settle down at the bottom. During fermentation carbon dioxide is released, this carbon dioxide begins to collapse after 4-5 days.

Carbon dioxide and heat are removed by cooling and in this process, sugar is converted into alcohol. During fermentation wort, specific gravity decreases. The green beer we got at the end of fermentation.

Green beer is harsh and bitter, in the lagering process it is stored in closed VAT for 0°C for 6-9 months. During this period secondary fermentation occurs that saturate beer with carbon dioxide and also material affecting the flavor like diacetyl, hydrogen sulfide, mercaptans, acetaldehyde is decreased by evaporation.

Ester is increased - any tannins, protein still left are precipitated. Time can be reduced by carbonation. The beer is then stored at high temperature i.e. 40°C to remove the hydrogen sulfide or acetaldehyde, further chilled at 2°C to remove the chill haze then it is carbonated and kept for 20 days for two months.

Pasteurization -

After aging, the beer can be pasteurized to kill the remaining yeast and prevent further alcohol production. This is accomplished by heating the beer above 135°F (57°C). This process, named after Louis Pasteur, is widely known for preserving milk. Interestingly, Pasteur originally developed this process to preserve beer in the 1860s. Pasteurization, however, is not used in the production of genuine draft beers. These beers are also known as "ice" beers since they must be kept refrigerated to preserve their flavor and slow the remaining yeast activity. Many consider the draft beers best in the aroma as well as taste.

Packaging -

The beer is transferred to a pressure tank and distributed in cans or bottles. During the transfer, oxygen and carbon dioxide are not allowed to lose. Cans and bottles are washed in hot water sodium hydroxide for sterilizing and then it is filled and crowned or capped. Further passed through the pasteurized and kept for 60°C for 30 minutes.

Byproducts -

Beer brewing produces several byproducts that can be used by other industries.

During the malting of the barley, rootlets form on the grain and drip off. These can be collected and used for animal feed.
The hops that are filtered out from the finished wort can also be collected and used again as fertilizer.
The residual yeast from the brewing process is a rich source of B vitamins. It can be put to use by pharmaceutical companies to make vitamins or drugs, or used as a food additive.
Used beer cans and beer bottles are routinely recycled.

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