Distillieries - Environmental Clearance

Distilleriesa) MaltMalt is derived from a cereal grain, usually barley, after being germinated for a limitedperiod and then dried. Malting, even if it is not carried out on a brewery site, is anintegral part of the brewing industry. The barley undergoes malting process to convert itto a form suitable for brewing. During the malting process, enzymes are generated, thegrain cell walls are broken down and some proteins are hydrolyzed. The malting processof barley includes cleaning, sorting, steeping, germination, drying and polishing. Thebarley is cleaned of dust and foreign materials and then sorted according to size with thesmallest kernels (grade IV) being sold as animal feed.b) Milling and mashingMalted barley is ground (either dry or wet) in a malt grinder so that the husk is left intactwhile the rest becomes very coarse powder, rich in starch and enzymes. The enzymesquickly degrade the starch to sugar on contact with water. The product, called sweetwort, is a mixture of partially degraded starch, sugars, enzymes, proteins and water(BPCE, 1986). The wort is separated from the spent grains by straining through a porousfilter in the lauter tun where the grains are sprayed or sparged with water in order toextract the maximum amount of useful material. Spent grains, spent hops and trubrepresent a valuable source of protein for animal feed.The spent grain yields typically 125-130 kg wet for every 100 kg of malt and itscomposition is 28% protein, 8% fat and 41% nitrogen-free substances (BPCE, 1986).c) Wort cooling and fermentationIn order to prepare for fermentation, the hopped wort is cooled to about 10 o C. Furtherprecipitation of proteins and tannin (known as cool trub or fine break) occurs during thecooling and aeration in preparation for fermentation which may continue from 2–16 days.Yeast is added in the fermentation vessel to induce fermentation of sugar wort which isconverted to CO 2 , alcohol, heat and new yeast cells. When the fermentation process iscompleted, the yeast is drawn off and used for a new batch of wort with the excess beingdisposed of as a by-product. The surplus yeast can be resold as animal feed. On a drysolids basis, the yeast contains 50-60% proteins, 15-35% carbohydrates and 2- 12% fatmaking it another valuable source of protein for animal feed (BPCE, 1986).Following the primary fermentation, the produced beer (green beer) is transferred tostorage or maturation vessels for a certain period of time before filtration. Prior tofiltration, the beer may be centrifuged, cooled to -1 o C to -1.5 o C to precipitate anysuspended solids. The beer is then filtered in a Kieselguhr (diatomaceous earth) filterfollowed by a filter cloth.d) Packaging and pasteurizationBright beer is stored and then filled into bottles or cans. In the process of filling, a smallvolume of beer (drip beer) is spilt. Bottling is usually preceded with bottle washing toremove any residual beer mold, cigarette butts, labels and dust particles.TGM for Distillery Industry 3-30 August 2010