1. Introduction
Crooked Spider is a small-scaled beer brewery having issues with the waste stream of Brewery Spend Grain (BSG). The BSG is now given away for free to the farmers as cow food. In this way Crooked Spider does not have to pay for their waste. Since BSG contains valuable nutrients BSG can be used in a more sustainable way and give it a value upgrade. Therefore, the key question for this report is: “How can BSG be processed in a more circular, affordable way?”
1.1 Objectives
First more information about the brewery Crooked Spider and more detailed information of BSG will be given. Then potential applications for the BSG will be researched and discussed. These applications will be compared on the aspects price, most circular, and ease of process. A simple cost estimation of the most suitable application for the BSG is made to know if it is feasible or not.
2. Background information
Background information for the report is given in this chapter.
2.1 Crooked Spider
This research is done for the beer brewery crooked spider. Crooked spider was started as an amateur brewer but, after winning prices they started producing commercially.
It is a small scaled company located in Wassenaar. The capacity on is maximum is 65.000 liters per month. To know how much BSG comes from the brewery an estimation is done. It can be estimated that 20 liters of beer give 7,5kg of BSG So, 24,375kg wet weight of BSG is produced per month. The BSG has a dry weight percentage of 30%. Because Crooked Spider is a small company the investment cost for this research would be around 8.000,00 euros. The available surface to build a small plant for the project is 12,5 to 25m2.
2.2 BSG
In the beer brewing process the main waste stream exists of brewers’ spent grain (BSG). This is about 85% of the total waste stream of the process. Barley grains are soaked in water to create wort, a solution of water and the soluble components in the barley grains, which is fermented to create the desired product: beer. The insoluble parts are filtered out and must be disposed of.
The barley grain exists of the gem, endosperm, and grain covering. In the beer brewing process the endosperm, which is rich in starch, is enzymatically depredated into both fermentable and non-fermentable carbohydrates, polypeptides, soluble proteins, and amino acids. The composition of the remaining BSG depends on the efficiency of the mashing, the hops residues, and the composition of the barley grains. In this report the average composition of the BSG stream given by The Institute of Brewing & Distilling will be considered.
Tabel 1. Average composition of BSG
Component % w/w
Hemicellulose 20-25
Cellulose 12-25
Protein 19-30
Lignin 12-28
Lipid 10
Ash 2-5
Hemicellulose and cellulose
BSG consists mainly of insoluble fibers, taking up about 50% of the dry weight of the material. Fibers are non-starch polysaccharides which are slowly digested and absorb water, which eases defecation.
Cellulose is mainly found as structural component of cell walls of green plants and is an un branched polysaccharide. It is taste- and oderless, and very crystalline. Unlike starch which requires only 60-70 °C to undergo a transition to amorphous, cellulose requires 320 °C and a pressure of 25 MPa before it becomes amorphous. Its chemical formula is (C6H10O5)n and many of its properties depend on its degree of polymerization, often between 7.000 and 15.000.
In comparison with cellulose, hemicellulose is amorphous, has little strength and is easily hydrolysed. It contains many sugar monomers which can include: mannose, galactose, arabinose, rhamnose, pentose, but mostly xylose. It is a branched polymer containing between 500-3.000 sugar units.
Protein
Protein take in average up 20% of the dry weight of BSG. From this protein content 30% consist of essential amino acids, which cannot be synthesized by the human body, with lysine being most abundant(14.3 % of the total protein content). Most abundant proteins are hordeins, glutelins, globulins and albumins.
Adults need 30mg of lysine per kilogram of bodyweight on a daily basis. A food component is considered to have a sufficient amount of lysine with at least 5.1% of the total protein content. Most food components meeting this requirement are meats, fish, eggs, and beans. Since BSG has a considerably different ratio in composition from the barley grains, BSG also belongs to this list.
Hordeins and glutelins are proteins mainly found in barley and some cereal. Globullins and albumins are blood proteins. Globullins are soluble in salt solutions. Albunins are water soluble and only moderately soluble in salt solutions.
Lignin
Lignin are complex organic polymers and are important in the formation of cell walls, functioning as filling material between cellulose, hemicellulose, and pectin components. They are rigid and do not rot easily. It is hydrophobic, which enables the cell vascular tissue to conduct water efficiently since the other materials are highly hydrophilic. As by product in the paper industry it is mostly burned as fuel and is wildly research as feedstock for biofuel production.
Lipid
The lipid composition in BSG predominantly consists of triglycerides (67%) and free fatty acids (18%). The triglycerides mostly present are trilinolein, dilinoleoyl palmitin, and dilinoleoyl olein. The fatty acid mostly found as triglyceride is linoleic acid. The lipids found in BSG can be used as functional food component, reducing blood cholesterol levels, and in the pharmaceutical and cosmetic industry.
Ash
From the mineral composition in BSG silicon, calcium, phosphorus, and magnesium are mostly present, which makes it an attractive source for animal feed.
3. Applications
To make from BSG a more valueble product than cow food, five possible applications are discussed. All applications are focused on human use and will be discussed on price, fhow circular the application is and, the ease of process.
3.1 Extraxtion of nutrients and protiens.
Recovery of constituents
BSG is a product containing a lot of individually valuable constituents, as already mentioned in chapter x. Recovering these individual constituents gives the opportunity to use them for a different purpose, which potentially could give them a value. Both chemical and enzymatic extraction can be applied for such recovery. The latter provides best control over the processes, allows to obtain bioactivity, and is more environmental friendly since it does not generate toxic side streams. In this chapter several recovering processes of various components in the BSG will be discussed.
Enzymatic hydrolysis to recover monosaccharides
Enzymes of various activities can be used for specific hydrolysis of carbohydrates. For full degradation of the BSG material a wide range of enzyme activities is required. Specific enzymes can be selected depending on the desired product and the extent of hydrolysis required. To make the polysaccharides more accessible through the rigid lignin structure in BSG, pre-treatment is found very useful. As can be seen in table x, using the same enzyme can give different yields depending on the pre-treatment used. Research has proven that the lower the lignin and hemicellulose content in BSG, the higher the efficiency of the hydrolysis.
Product Enzyme Conditions Yield Pre-treatment Reference
Glucose Celluclast 45 °C
96 h 30-90% (depending on pre-treatment) 1) Untreated,
2) Dilute sulphuric acid
3) dilute acid and dilute sodium hydroxide
Glucose Celluclast 50 °C
20 h 100% High-pressure treatment
Glucose, cellobiose Celluclast 45 °C
96 h 99% Dilute acid and dilute alkaki
Monosaccharides Neurospora crassa crude perparation 30 °C
24 h 50 % of total pentose
60% of total glucose Alkali
Monossacharides Fusarium oxysporum crude preparation 30 °C
24 h 40 % of total pentose
70 % of total glucose Alkali
Monossacharides and oligosaccharides Depol 740, Depol 686, Promod 24L, Alcalase 50 °C
4 h 36 % of BSG None
Table 1. Various studies showing the yield of hydrolysis of BSG with different types of enzymes and pre-treatment
The hydrolysis of cellulose consists of two stages: primary hydrolysis, where soluble intermediates are released from the surface of the cellulose molecule, and secondary hydrolysis, where the intermediates are further hydrolysed into ultimately glucose.
Strenght Weakness
Very specific
Can have very high yields Pre-treatment with chemicals could make the product unusable in the food industry / could give toxic waste streams
Opportunities Threats
Lipid recovery
The lipids present in BSG could be widely used in the pharmaceutical, cosmetic, food, personal care products, polishes and coatings, and the biofuel sector. Especially the biofuel sector has potential as lipids were used as fuel before petroleum came on the market, with the need in renewable energy sources lipids came to the front again.
To be able to extract lipids in an efficient way, cell disruption and a solvent able to reach the intracellular inclusions are required. There are several pre-treatment techniques which can achieve this, but they do either require high capital investment, high operational costs or both. A solvent would be required to dissolve the lipids to be able to extract them.
Research on how to extract lipids from algae proofed that the best method to extract lipids from biomass is by surfactant treatment. This is a method is more sustainable, efficient, and economical than extraction without surfactant treatment. Surfactants are able to isolate components by binding to a cell. To extract the lipids, the mixture is first vortexed after which it is filtered through a membrane. The crude lipids in the filtrate are dried in a nitrogen evaporator. To be able to use this method to full efficiency research needs to be done to find out which surfactant would be suitable for lipid extraction from BSG.
Protein recovery
BSG is a good source of valuable proteins, which gives it good commercial opportunities. These proteins are insoluble in water which makes them difficult to extract. The recovery can be increased by enzymatically pre-treating. The material breakies down the proteins into water soluble peptides.
There are several methods useful for protein recovery involving using protein precipitant, adjustment of pH, or ultrafiltration. Proteins can be inexpensively extracted with sodium dodecyl sulphate as extractant after which they are precipitated by adding ethanol following chilling in the refrigerator.
3.2 Making products
Production of construction bricks
Green building is one of the recent technologies for the world to reduce brick weight and increase its thermal insulation ability. They factories usually use the waste from the other agro-industrial wastes such as sawdust, tobacco residues, grass and process tea waste.
BSG is the waste from the beer brewery and it cost money for the brewers to dispose them, however base on the research (Demir, 2008), BSG is suitable to make the bricks with other materials together. BSG is made of low amount of ash and high amount of fibrous materials which are lignin, hemicellulose and cellulose, so the BSG have higher strength, higher porosity (higher water absorption capacity) and a lower density. Due to its characters, which give the bricks better properties of thermal insulation than those produces from a similar production clay.
The procedure to make this ideal happen is simple as the normal bricks production. Clay is the normal main materials for making bricks, the use of the clay is to contribute to green buildings and also ensure that there is zero wastage of the raw materials at all. The overall process for making bricks consists grinding, extrusion, chamfering the brick, coating, drying, firing and packaging. The process flow is followed:[1] The world of brick production. (2018). Retrieved from https://clay-wienerberger.com/expertise/the-world-of-brick-production-
Figure 1: Bricks production flow chart
Back to our topic, how to make bricks is not what we need to worry about because building a bricks factory is beyond the brewery’s ability， so trading the BSG to the bricks factory maybe suitable for us.
The advantage of using BSG into the bricks production has the following facts:
1. Improve the high-water absorption rate and erodibility of plant fiber in cement substrate: Natural plant fiber is composed of a single fiber cells through intermediate sandwich cementation united, the intermediate sandwich is mainly hemicellulose and lignin and oligosaccharides. It which are in the alkaline environment of cement slurry are degraded leaching put forward a lot of simple sugars, oligosaccharides, lignin, etc., which can lead good retarding for the bricks.
The water absorption of natural plant fiber is very strong. The experimental test shows that the water absorption of 5 m in of BSG fiber is 58%~84%, and the saturated water absorption will reach 10%~l53% mockery, which will seriously reduce the strength of concrete. Because of the depolymerization of plant fibers in the submerged environment, the tensile strength of the fibers decreases. When the complete solution of the fiber is formed in the concrete, a large number of connected pores are formed, which seriously affects the durability and mechanical properties of the material. [2] wang, L. (2018). Study on cement based foam insulation wall material produced by plant fiber [Ebook] (p. 3). Dalian: Dalian University of Technology. Retrieved from http://www.zgxpj.com.cn/file/pdf/wenxian/4997695.pdf
2. Better Air Quality
In buildings, plant fiber bricks provide better air quality because they do not use any kind of volatile organic compounds, which affect the air in any way. As almost all VOCs are affecting indoor air quality. Plant fiber bricks are made in this way, they do not depend on molds, which makes air quality seriously drop. Clay bricks do not encourage any form of mold, no matter whether it is dry or wet, so it is a good substitute for green building. On the other hand, any other kind of wall material will grow mold, especially in wet climate, which not only affects air quality, but also causes huge maintenance costs.
3. Superior Acoustics
Except reducing air pollution, clay with plant fiber bricks can also greatly reduce noise pollution. They have good resistance to various types of voice penetration and have more than 40 STC (sound transmission level). Therefore, compared with other building materials, the indoor environment of green building made of clay with plant fiber brick has good acoustic comfort.
4. Zero wastage of raw materials
Clay bricks are made of clay and shale, they also exist naturally near the manufacturing units. This also reduces the transportation cost of raw materials, thereby affecting the overall cost and environment. Moreover, almost all raw materials used for clay brick mining are eventually used in some form. No matter how the percentage of processed materials, clay and shale will eventually run out of production units. All low-quality bricks that do not meet the strict standards are reused and reused during manufacturing or in landscaping. Generally speaking, the absolute zero loss of raw materials in clay brick production has a positive and tremendous impact on the environment and green buildings.
BSG is the waste from beer brewery, without any further use, they can only be treated as rubbish and burned, it will cost money and seriously bad for the environment. The hemicelluloses and cellulose inside the BSG is higher enough to meet the quality of the bricks. The BSG will be grinded and then mixed with other materials, so the waste of BSG will also be zero.
5. Durability
Clay bricks are very durable and can last for decades with little maintenance. More importantly, they are made of organic materials in modern manufacturing plants, which optimizes the resources and energy used in the manufacturing process. In addition, thermal efficiency is one of the factors involved in green building, which leads to a reduction in the cost of air-conditioning and heating. [3] Clay: A Sustainable Green Building Material Choice for Architects – Go Smart Bricks. (2018). Retrieved from http://gosmartbricks.com/clay-a-sustainable-green-building-material-choice-for-architects/
After stating the advantage of using BSG to make bricks, it is still not possible for a brewery company to make bricks by themselves, so selling BSG to the bricks factories is one of the possibilities for the brewery. However, using BSG as a part of the raw materials for the bricks production still has barriers, the pre-treatment for extract nutrition from the BSG will cost effort and money, it is not a must because in the firing process of the bricks production, the high temperature (over 1100 degree) will sterilize all the input materials, but it is waste of the nutrition inside the BSG. The second difficulty is the Using BSG as the side raw materials for the bricks productions is not common for now, it is hard to find a company wants to pay for the cost, that are what the company need to concern.
Production of BSG paper
The application potential of brewery’s spent grain (BSG) in pulp and paper industry was evaluated. Chemical analysis shows that the by-products of the brewing process have 35.9% of hemicellulose, 22.7% of protein, 17.7% of cellulose, 10.1% lignin, 9.1% of extract and 4.5% ash in ethanol / toluene. Raw materials were pulping by Kraft method, soda process and neutral sulfite semi chemical method. The corresponding pulping yield is close to 17%, and kraft and soda methods are 64.6% respectively. Pulp fibers are short (about 0.4 mm) and pulp has fairly high fine content (close to 20%). The chemical compositions of kraft pulp and soda pulp were 4.3% and 4% ash, 1.6% and 1.1% protein, 55.9% and 60.2% cellulose, 35.7% and 32.4% hemicellulose respectively. The structural strength of the laboratory paper is relatively poor, but the corrugated paper test and the concora medium test are similar to the reference material, which reveals the potential of BSG paper production. [4] Pulping and papermaking potential of brewery spent grain. (2018). Retrieved from https://www.researchgate.net/publication/282717292_Pulping_and_papermaking_potential_of_brewery_spent_grain
Table 1: Component of kraft and soda pulp
Table 2: Component of BSG
Using BSG to make paper is just on the experiment level, the University of Washington has made the first paper at 2017. The procedure of making BSG paper is same as the normal paper making. It is possible to figure out the paper production and use the same technology to make the BSG paper.
Preparation of raw materials
There are different forms of wood that the pulp mill receives. It depends on the pulping process and the source of the raw material. When the BSG are used as raw materials, they are usually rolled in large steel tanks that can be washed with water. If the pulping process needs chemical digestion, the dropped shells will be minced. The raw materials are then sized, cleaned and temporarily stored for further processing.
Fiber separation
During the fiber separation stage, several pulping technologies will be dispersed. These chips are put into a large pressure cooker (the digester), adding appropriate chemicals in kraft paper chemical pulping.
Then steam digestion chips were used to separate fibers and partially dissolve lignin and other extracts at specific temperatures. Some tanks operate continuously at a constant feed rate, and charge the liquid intermittently and deal with a batch at one time.
After digestion, the treated pulp is discharged into the pressure vessel. The steam and volatile substances are closed here. After that, the treated pulp is returned to the chemical recycling cycle.
In the process of wood grinding, the spalling wood is forced to rotate the grinding wheel. The grinding and thermal mechanical pulp are produced by slicing. These chips are ground by making them rotate rapidly through two processes.
In the second stage of refining, pulp is screened and cleaned, and most of the process water is removed for paper making.
bleaching
Raw pulp contains a considerable amount of lignin and other discolouration and must be bleached to produce light or white paper for many products. Further lignin removal is achieved by dissolving extra lignin from cellulose by chlorination and oxidation. These include chlorine dioxide, chlorine, sodium hypochlorite, hydrogen peroxide and oxygen.
Sodium hydroxide and strong alkali are used to extract lignin from fibrous surface. Bleach and the sequence of its use depend on many factors, such as the relative cost of bleaching chemicals, types and conditions of pulp.
Mechanical pulp bleaching is different from chemical pulp bleaching. Mechanical pulp bleaching is to reduce fiber yield by reducing lignin removal.
Chemical substances used to bleach mechanical pulp selectively destroy colored impurities, but make lignin and cellulose materials intact, including sodium bisulfite, sodium or zinc hydrosulfite, calcium or sodium hypochlorite, hydrogen or sodium peroxide, and the sulfur dioxide-borol process.
Papermaking process
Bleached or unbleached pulp can be further refined to cut fibers and make the fibers rough, so as to enhance the formation and adhesion of fibers into the paper machine.
The water is added to pulp to make a fine mixture containing less than 1% fibers. The diluted slurry is cleaned in the cyclone cleaner and then screened into the wet end of the paper machine in the centrifugal screen. The diluent is distributed through a header box evenly distributed on the width of the paper to be formed. [5] Pulp and Paper Manufacturing Process in the Paper Industry. (2018). Retrieved from https://www.pulpandpaper-technology.com/articles/pulp-and-paper-manufacturing-process-in-the-paper-industry
Figure 2: BSG paper form the University of Washington [6] French. (2018). University of Washington makes paper from brewing waste. Retrieved from https://www.thedrinksbusiness.com/2017/10/university-of-washington-makes-paper-from-brewing-waste/
3.3 Energy
NICK
burn it
biogas
3.4 Compost
Grow medium
An alternative use for BSG could be compost or as grow medium for microorganisms and enzyme production. For this case the BSG has a high moisture content, polysaccharide and protein content which makes it suitable for this application.
Micro organisms
To use the BSG as a grow medium the BSG has to be dried for 24 hours on 60degrees Celsius. Than the dried BSG has to be grinded until it is a powder of 0.06mm and as last filtered. The BSG powder is mixed with agar which is a gel like substance to contain microorganisms with a ratio agar: spent grain, 01:04. The following microorganisms are able to grow in this way: Staphylococcus aureus, Escherichia coli and Streptococcus pyogenes.
The BSG growing medium can be sold to labs so they can make test. The application for BSG to be used as a grow medium could be done in the factory.
Strenght Weakness
Specific use
You have to find a buyer for the medium
Opportunities Threats
costs
Enzymatic hydrolysis to recover monosaccharides
Enzymes of various activities can be used for specific hydrolysis of carbohydrates. For full degradation of the BSG material a wide range of enzyme activities is required. Specific enzymes can be selected depending on the desired product and the extent of hydrolysis required. To make the polysaccharides more accessible through the rigid lignin structure in BSG, pre-treatment is found very useful. As can be seen in table x, using the same enzyme can give different yields depending on the pre-treatment used. Research has proven that the lower the lignin and hemicellulose content in BSG, the higher the efficiency of the hydrolysis.
Product Enzyme Conditions Yield Pre-treatment Reference
Glucose Celluclast 45 °C
96 h 30-90% (depending on pre-treatment) 1) Untreated,
2) Dilute sulphuric acid
3) dilute acid and dilute sodium hydroxide
Glucose Celluclast 50 °C
20 h 100% High-pressure treatment
Glucose, cellobiose Celluclast 45 °C
96 h 99% Dilute acid and dilute alkaki
Monosaccharides Neurospora crassa crude perparation 30 °C
24 h 50 % of total pentose
60% of total glucose Alkali
Monossacharides Fusarium oxysporum crude preparation 30 °C
24 h 40 % of total pentose
70 % of total glucose Alkali
Monossacharides and oligosaccharides Depol 740, Depol 686, Promod 24L, Alcalase 50 °C
4 h 36 % of BSG None
Table 1. Various studies showing the yield of hydrolysis of BSG with different types of enzymes and pre-treatment
The hydrolysis of cellulose consists of two stages: primary hydrolysis, where soluble intermediates are releases from the surface of the cellulose molecule, and secondary hydrolysis, where the intermediates are further hydrolysed into ultimately glucose. The suger produced from the enzymes can be used in the beer brewing process.
The pretreatment increases the yield with 10%. The total product consists 22% of sugars which can be extracted with water. The researchers found are only preformed on small scale in terms of miligrams. It is not proven that it will work on a larger scale which makes it suitable for using the sugar in the beer brewery process.
Strenght Weakness
Very specific
Can have very high Pre-treatment with chemicals could make the product unusable in the food industry / could give toxic waste streams
Opportunities Threats
yields can be used for beer production costs
Compost
The BSG is a high carbon source but need to be mixed with other carbon sources, organic waste, to make it good quality compost.
The compost has to lay 90 days and turned frequently to make sure it stays aerobic. If there is not enough air available in the composting process the process will become anaerobic and produces ammonia which gives bad odors.
Another easier way to do it is sell the dried BSG as organic fertilizer. The dried BSG can be applied directly on agricultural land. The BSG will increase the water capacity of the soil and increase the soil nutrients.
Strenght Weakness
Very specific
Can have very high Dirty and havey work
Bad odors if not turned frequently
Large space is needed
Opportunities Threats
Helps against soil degradation Microorganisms which grow in the compost can make the workers ill.
https://www.ajol.info/index.php/ajb/article/view/92219/81673
3.5 Human food
Replacing conventional flour with a single piece of bread will increase fiber content by 50%, protein content by 10%, essential amino acid content by 10%, and calories by approximately 7%. This huge change in bread nutrition is very significant and can be sold to specific market segments. These incredible nutritional values will attract many people. In addition, waste grain is reused as a beer brewing company’s sustainable food waste solution.
The brewing spent grain opens up many creative ways to recreate recipes.
Use a batch of chocolate dark chocolate, or bread. You can use waste food in as
many recipes as you can, when you add flour in it. after dehydrating and
grinding, waste grains can be used for more food applications.
BSG making brownies.
Ingredients: ½ cup butter 1 cup sugar ¼ Tsp. salt 1 cup
cocoa powder 1 Tsp. vanilla extract 2 eggs ½ cup white flour ½ cup wet spent
grains ⅔ cup chocolate chips
Melt butter and stir with sugar and salt. Stirring In cocoa, then
eggs and herbs. Stir white flour and mix well. Wet flowers cereals. If batter
is too thick to spread, add water make a flowing batter. Bake in 35 to 40
minutes at 350 degrees.
Advantages:
1. The process is simple, it can save time and money for company.
2. Crooked Spider is a beer brewing company so you don’t need to spend a lot of money on buying new equipment.
3. Compare with regular white flour brownies, BSG brownies doubled the fiber content. Deceased 7% of calorie content, increased 50% protein content and increased 10% of essential amino acid content.
Disadvantages:
1. The taste of BSG brownies might not as good as regular white flour brownies, most people choose to eat brownies is because its tastes, they don’t care a lot on its nutrient. BSG brownies can not have a very big market nowadays.
Regrained energy bars
As long as sugar are already out of BSG after beer brewing, so it gives an optimal access to get protein, fiber and other micronutrients in BSG.
By using a grinder to grind BSG into BSG powder, add other ingredients into the powder such as honey, chocolate. Lastly incorporate this mixed powder to BSG energy bar.
Advantages:
1. Simple process, it means BSG energy bar is easy to make, it doesn’t need many human power and money to do it.
2. It doesn’t require many equipment, beer brewing company has most of equipment.
3. BSG energy bar have richer nutrition.
4. The taste of BSG energy bar is flexible, by adding different ingredient can have different tastes.
5. Have a large number of selling target.
Disadvantages:
1. Because of the BSG, the taste of BSG energy bar might not as smooth as other kind of energy bar. Some people might not accept it.
http://www.gibbs-lab.com/wp-content/uploads/2016/05/Spent-Grain-Creative-Waste-Solutions.pdf
https://www.regrained.com
4. (Name of best) Applications
Compaire with other applications
Most suitable application is choosen and explained in more detail.
5. Cost estimation
?
6. Conclusion
7. Discussion
8. References
Appendix
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