Cleaning In Breweries

INTRODUCTION Cleaning and sanitation are an integral part of a brewery and should be taken into consideration at every phase of the beer brewing process. Cleaning proceeds sanitation and prepares the way for sanitation treatment by removing organic/inorganic residues and microorganisms from the brewery equipment. Sanitation reduces the surface population of viable microorganisms after cleaning and prevents microbial growth on the brewery equipment. It is important to note that the power of sanitizing agents (disinfectants) is reduced by the presence of dirt. This is why cleaning always precedes sanitation. Generally cleaning should be done before and after the use of all equipment. It is important to rinse all equipment with clean water after the use of sanitizing agents to avoid traces of detergents in the wort which can reduce foaming of the final beer not to talk of the bad taste which may result. Beer is a fermented beverage made from barley, hops, water and yeast and sometimes other ingredients. There are three major beer types which are ales, lagers and specialty beers.

1.2 THE BREWING PROCESS Brewing is aimed at obtaining quality liquid extraction (wort) in order to produce beer. It aims at dissolving components preformed during malting, using enzymes produced in this process to transform starch of malt and adjuncts into fermentable sugars and unfermentable components. The brewing process involves the following steps; -

Milling

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Mashing

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Wort separation

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Wort boiling

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Wort cooling

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Fermentation

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Maturation

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Filtration and

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Conditioning

Reception malt

Weighing

Storage

Sorting and Screening

Foreign particles and dust

Weighing

Storage Reception of Gritz

Milling Transfer of mash Correction

Mashing Mash Tun

Filtration of mash

Mashing-in Adjunct Cooker Spent Grains

Buffering in Tank Additives Boiling in kettle (Hops)

Additives (Hops)

Boiling in Kettle

Clarification of cast wort

Hot break or Trubs

Cooling of Wort

Aeration of Clear Wort

Yeast

Fermentation

Maturation

Filtration of Green Beer

Diagram 1: Block Diagram of the Brewing Process Conditionning

CO2

Yeast

RECEPTION At reception the malt is sorted from foreign substances like stones, metallic objects or even different cereals with the help of a destoner and a magnet. It is then screened according to size and weight in order to eliminate sizes and weights that may hinder milling. There is removal of dust particles with the use of an aspiratory system. This is to avoid blockage of the filter during separation of wort and also explosion at certain quantities in the silos. MILLING In order to obtain maximum extract, the malt must be reduced to smaller particle that will permit maximum enzyme action during the mashing process. Thus the objectives of grinding the malt are -

to split the husk (remain whole) in order to expose the inner portion of the grains known as the endosperm.

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To control particle size to ease wort recovery.

MASHING This is the of converting the starch of milled malt and solid or liquid adjuncts into fermentable sugars to produce wort of desired composition. The composition of wort will vary according to the mashing method. Mashing involves mixing milled malt and solid adjunct, with water at a set temperature and volume to continue the biochemical changes initiated during malting. The principal enzymes responsible the conversion are α and β– amylases. The objective of mashing is to obtain the best solid/ liquid extraction. The extract here represents the quantity of dissolved matter measured in saccharose equivalents. There exist different methods of mashing, which will determine the composition of the wort obtained. Some of these method are listed below;

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Infusion mashing

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Decoction mashing

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Temperature controlled mashing

WORT SEPARATION After mashing, when all the starch has been broken down, it is necessary to separate the liquid extract from the solids (spent grain particles and adjuncts). Wort separation important because the solids contain large amounts of protein, poorly modified starch, fatty matter, silicates and polyphenols (tannin). The objective of wort separation (lautering) include the following -

To produce clear wort

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To obtain good extract recovery

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To operate within the acceptable cycle time.

It should be emphasised that the quality of the grist from the mill can greatly affect wort clarity, extraction recovery and overall lauter time. This separation can be carried out using a -

Lauter tun

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Filter press

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Strain master

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The 2001 MEURA filter

WORT BOILING The principal objectives of wort boiling are -

To stabilize the wort

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Arrest of enzyme action

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To cause coagulation of proteins and tannins (Hot-break)

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To precipitate calcium phosphate which leads to a consequent fall in pH

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Distilled volatile materials (H2S) and Dimethyl Sulphite etc.

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Evaporation of water and therefore concentration of wort

Since hops are present in the wort, boiling will also lead to the wort being filtered by hop resins and essential oils and some tannins also being added to it. Coagulation of proteins usually known as trub or hot break is actually a biochemical reaction between proteins and polyphenols. This reaction tends to reduce the amount of α-acid in the wort.

WORT CLARIFICATION This clarification is carried out using a decanter or whirlpool tank. A whirlpool is more efficient. In the whirlpool, a batch of wort is pumped at high speed (2-10m/s) through a pipe tangential to the tank. As the suspended parties move along the sides of the tank, frictional force will reduce momentum to almost zero. The inclined nature of the base of the tank helps these particles to be collected at the base. Clear wort can then be withdrawn. WORT COOLING Plate heat exchangers, are the most common devices used for wort cooling. They comprise many stainless steel plates, with a shallow cavity between each plate. The wort comes in at a higher temperature of ≈ 80-85°C and goes off the last plate at 15°C, water enters at about 10°C and come out at first plate at 75-80°C. If the brewer requires wort at temperature s<10°C, then they either use water at a much lower temperature, or the heat exchanger may have a second section, chilled with refrigerated water, alcohol or brine. FERMENTATION BEER CONDITIONING Following primary fermentation, the "green" or immature beer is far from finished because it contains suspended particles, lacks sufficient carbonation, lacks taste and aroma, and it is physically and microbiologically unstable. Conditioning reduces the levels of these undesirable compounds to produce a more finished product. The component processes of conditioning are: • maturation, • clarification, and • stabilization