ABSTRACT

Recent advances in biotechnology ensure that brewer’s spent grain (BSG) is no longer regarded as a waste but rather a feedstock for producing several products. Based on this, it is an undeniable fact that BSG has its own potential for sustainable reuse through biotechnological processes. Thus, efficient recycling of BSG requires extensive work towards exploring newer applications and maximizing use of existing technologies for a sustainable and environmentally sound management, more insight is required for large scale utilization, which involves both laboratory and field experiments with proper control processes.Lignocellulosic substrates, being cheap and readily available, have recently gained considerable interest because of their possible use in other processes. However, the utilization of BSG is limited especially in developing countries and new ways of making use of this residue would be beneficial for the process economy. Brewers’spent grain (BSG) is the major by-product of the brewing industry, representing around 85% of the total by- products generated. BSG is a lignocellulosic material containing about 17% cellulose, 28% non -cellulosic polysaccharide, chiefly arabinoxylans, and 28% lignin. BSG is available in large quantities throughout the year, but its main application has been limited to animal feeding, it can also serve as an attractive adjunct in human nutrition.Recently,attempts have been made to use BSG in biotechnological processes, such as in the production of laboratory medium for the cultivation of microorganisms.This research emphasized on the use of brewers spent grain in the production of microbial laboratory medium use for the cultivation of microorganisms.The spent grain was collected from Intafact brewery Onitsha,Nigeria.The spent grain  was mixed with crude cassava starch as a gelling agent to formulate a medium that will favor the growth of microorganisms especially fungal organisms, several analysis were ran on the spent grain which include proximate analysis(ash, fiber, protein, moisture, carbohydrate ,fat) , after several trials to formulate a replica of a microbial laboratory medium but this time with waste products of other industrials for cost effectiveness , at a certain concentration of crude cassava starch and specific quantity of spent grain the formulated medium gelled after been sterilized in an autoclave and left to cool, after doing both spread , pour , and point inoculation method ,the formulate medium favored fungal growth faster than bacterial growth ,finally the formulated medium was compared with a standard medium for the cultivation of fungal organisms which is sabouraud dextrose agar (SDA) the fungal organisms grew faster and better on the formulated cost effective medium.

CHAPTER ONE

Beer is the fifth most consumed beverage in the world apart from tea, carbonates, milk and coffee with an estimated annual world production exceeding 1.34 billion hectoliters in 2002 (Fillaudeau et al., 2006). In the manufacture of beer, various residues and by-products are generated. The most common ones are spent grains, spent hops and surplus yeast, which are generated from the main raw materials (Mussatto, 2009). Spent grains are the by-products of mashing process; which is one of the initial operations in brewery in order to solubilize the malt and cereal grains to ensure adequate extraction of the wort (water with extracted matter) (Fillaudeau et al., 2006). Following different separation strategies, the amount of brewers’ spent grain (BSG) generated could be about 85% of the total by-products (Tang et al., 2009), which accounts for 30 to 60% of the biochemical oxygen demand (BOD) and suspended solids generated by a typical brewery (Hang et al., 1975). It was reported that about 3.4 million tons of BSG from the brewing industry are produced in the EU every year (Stojceska et al., 2008), out of which UK alone contributes over 0.5 million tones of this waste annually. However, Brazil, the world’s fourth largest beer producer (8.5 billion liters/year) in 2002, generated 1.7 million tons of BSG (Mussatto et al., 2006). Thus, BSG is a readily available, high volume low cost by-product of brewing and is a potentially valuable resource for industrial exploitation (Robertson et al., 2010). Thus, increased endogenous metabolism as well as high proteolytic activity in BSG affects its composition within a very short time (Ikurior, 1995). Several attempts have been made in utilizing BSG in animal feeds, production of value-added compounds (xylitol, lactic acid, among others), microorganisms cultivation, or simply as raw material for extraction of compounds such as sugars, proteins, acids and antioxidants. It was also found to be applicable in enzymes production, as adsorbent for removing organic materials from effluents and immobilization of various substances (Mussatto, 2009). This review describes the feasibility of transforming the BSG into suitable laboratory medium for the growth of microorganisms, with environmental pollution assuming an alarming rate in Nigeria, the disposal or further utilization of industrial waste has become an important factor in the efficient operation of any plant. Waste utilization or disposal in food industries is a major problem in maintaining sanitation and avoiding pollution of land , air , water (Gregory et al., 2008). The most abundant renewable resource produced all around the world is represented by lignocellulosic biomasses (Prasad et al.,2007) , which include agricultural residues ,food farming wastes , tree pruning residues and the organic and paper fraction of urban solid waste.

Spent grains have characteristics that make it a prime candidate for many other important and valuable uses. As a human food additive or a nutriceutical product, spent grain would command a premium over its current usage. As an energy source for a fermentation process.it could produce not only a valuable fuel , but also nutrient-rich effluents and solid organic matter for composting .

A global interest in using the lignocellulosic residues and waste as sources of added value bi-product is rising due to their renewability , low cost , abundance , and non- competitiveness with food (Liguori et al ., 2013) , boosting the development of the bio- refinery concept and advancing sustainable waste management  (Dusselier et al ., 2014) .

Food waste contains such high concentration of nutrients carbohydrates, proteins, fats and minerals. such that if the waste are not immediately disposed off or utilized , due to high concentration of nutrients  , it may attract insects , rodents , spoilage organism or even pathogenic organism (Gregory et al ., 2008)

Raw materials in form of food industrial waste have been channelled towards the production of industrial, commercial and pharmaceutical products that include energy and fine biochemical products (Miller, 1998). The waste of a company is seemingly the raw material of another. in actual sense , no waste is a waste , the waste generated by the beer industry is becoming complex , difficult to treat and expensive . since it is economically feasible and possible to develop many economic and sellable products from brewing by-products , not only is disposal cost saved , it helps in prevention of environmental pollution , helps in agricultural and also in human and animal nutrition .

Brewers spent grain(BSG) are the major by-product  of the beer industry , representing around 85% of the total by product generated , BSG contains 17% cellulose , 28% non cellulosic polysaccharide and 38% lignin (Mussato and Robert, 2005) . BSG can serve as an adjunct in human nutrition due to high protein content. They have also been used in feeding both ruminant and monogastric animal. it has also been shown to be an excellent media for microbial growth of yeasts and moulds (Mussato , 2006) .

Recently , attempts have been made to use BSG in biochemical processes such as in the cultivation of mushroom and actinobacteria (Mussato , 2006) . BSG is also used as supplement in baking and confectionaries up to 30% substitute (Nascimento et al., 2002).

Brewers grains are the solid residue left after the processing of germinated and dried cereal grains (malt) for the production of beer and other malt products (malt extracts and malt vinegar). Though barley is the main grain used for brewing, beers are also made from wheat, maize, rice, sorghum and millet. In the brewing process, grains are soaked in water until they germinate and then dried to produce the malt (malting). The malted grains are milled and steeped in hot water so that enzymes transform the starch into sugars (mashing/saccharification). The resulting sugar-rich liquid (wort) is then boiled, filtered and fermented to produce beer. Brewer’s grains are collected at the end of the mashing process, once all sugars have been removed from the grain. The remaining product is a concentrate of proteins and fibre that is suitable for animal feeding, particularly for ruminants (Crawshaw, 2004). Brewer’s grains are a highly variable by-product whose composition and nutritional value depend on the grain used, on the industrial process (temperature, fermentation, etc.) and on the method of preservation. Brewers grains are sold wet or dried, and can be ensiled (Blezinger, 2003).

Wet brewer’s grains are a highly perishable and bulky product that is costly to transport. Their distribution is, therefore, limited to a radius of 150-350 km around the brewery. Dehydration, despite its high energy cost, facilitates the distribution of brewers grains beyond their area of production, as dried brewers grains are less bulky and less expensive to transport (Crawshaw, 2004).

Wet brewer’s spent grains contain 75-80% water and deteriorate rapidly due to the growth of bacteria, yeasts and fungi. It is advisable to use them as soon as possible after reception and to make sure that they are in good condition before utilization (Wyss, 1997; Wadhwa et al., 1995; Aning et al., 1994). The palatability of brewers grains decreases with storage time. Maximum recommended storage duration depends on temperature and climate: 2-5 days in warm temperature and 5-7 days in cold weather (Thomas et al., 2010; Amaral-Philips et al., 2002; Aning et al., 1994), though some authors claim that 30-day storage is feasible in winter (Kim et al., 1996). Feed mixtures containing brewers grains spoil quite rapidly, so any excess feed that animals have not consumed should be discarded (Göhl, 1982).

This work was carried out to look into the possibility of preparing medium from BSG for the cultivation of microorganism.

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