Biotechnological Innovations and Alternative Uses for the Sugar Waste-Stream, Molasses

Biotechnological Innovations and Alternative Uses for the Sugar waste-stream, Molasses.

Report Prepared by:Kevin Byrne

Caitríona Daly

Yvonne Anders

Subject:Waste Management.

Lecturer:Dr. Michael Broaders.

Date of submission:16/12/’05

Contents.

ChapterPage Number

Introduction………………………………………………………………….3

Production of Molasses

Types of Molasses

Boston Molasses Flood (History)

Primary Uses of Molasses……………………………………………….12

Silage Preservation

Biotechnological Uses of Molasses…………………………………….17

Bioethanol……………………………………………………………..17

Production Process

Suitable Microorganisms

Uses of Bioethanol

SCP……………………………………………………………………26

Production Process

Case Study – Indonesia Repetila III

Citric Acid……………………………………………………………..34

Bioremediation Using Molasses………………………………………..39

Conclusion………………………………………………………………….42

References………………………………………………………………….43

Introduction.

Molasses is a liquid sugar extracted from the juice of the sugar cane or sugar beets. In making refined table sugar, the sugar cane is harvested, mashed and the raw juices are boiled to extract the sugar grains for further processing. The syrup is placed into a very large pan for boiling, the last stage. In the pan even more water is boiled off until conditions are right for sugar crystals to grow. You may have done something like this at school but probably not with sugar because it is difficult to get the crystals to grow well. In the factory the workers usually have to throw in some sugar dust to initiate crystal formation. Once the crystals have grown the resulting mixture of crystals and mother liquor is spun in centrifuges to separate the two, rather like washing is spin dried. The crystals are then given a final dry with hot air before being stored ready for despatch.(1)The remaining syrup is called first molasses. First molasses is then thinned with water and re-boiled so that more raw sugar can be extracted. The leftover syrup from the second boiling is second molasses, and so on. After three or more boilings, molasses is called blackstrap, which has a bitter taste, and is used primarily for cattle feed and industrial purposes.

Molasses is sold in a variety of grades. The highest grade is made from clarified and reduced pure sugarcane juice, before the sugar extraction process begins. The Grandma Molasses Company sells this as their “gold label molasses.” Their “green label” is the first molasses described above. Either high grade or first molasses is appropriate for cooking. Molasses from sugar beets has a bitter taste, and is not sold for consumption.

Some manufacturers will make sugar and molasses from sugar cane which is picked unripe and then ripened through exposure to sulphur. In that case, molasses will be labelled “sulphured.” Although cheaper, try not to buy sulphured molasses – the sulphur taste is especially retained in the syrup.

Sugar Beet (Beta Vulgaris) is a member of the order Chaenopodeacae. It has been developed by genetic selection from the commonly found wild plant sea beet, strains of the species with large root size and high sugar content being developed over time.

Fig1.1. World Map of Sugar cane and Beet Production

Sugar Beet Molasses

Molasses from the sugar beet is different from cane molasses. Only the syrup left from the final crystallisation stage is called molasses; intermediate syrups are referred to as high green and low green. It is about 50% sugar by dry weight, predominantly sucrose but also containing significant amounts of glucose and fructose. The non-sugar content includes many salts such as calcium, potassium, oxalate and chloride. As such, it is unpalatable and is mainly used as an additive to animal feed or as a fermentation feedstock. It is possible to extract additional sugar from beet molasses through a process known as molasses desugarisation. The processing starts by slicing the beets into thin chips. This process increases the surface area of the beet to make it easier to extract the sugar. The extraction takes place in a diffuser where the beet is kept in contact with hot water for about an hour.The diffuser is a large horizontal or vertical agitated tank in which the beets slices slowly work their way from one end to the other and the water is moved in the opposite direction.This technique exploits industrial scale chromatography to separate sucrose from non sugar components. The technique is only economically viable in areas where the price of sugar is supported above the world market. The non-sucrose elements in the beet sugar production process are called molassegenic because they take equal amounts of sucrose with them to the molasses stage where it cannot normally be economically extracted.

Fig.1.2 The Sugar Beet Plant

There are three major types of molasses: unsulphured, sulphured and blackstrap. There are also three major grades of molasses: first molasses, second molasses, and blackstrap molasses. The Unsulphured molasses is the finest quality. It is made from the juice of sun-ripened cane and the juice is clarified and concentrated. Sulphured molasses is made from green (not yellow) sugar cane and is treated with sulphurfumes during the sugar extraction process. Each season, the sugar cane plant is harvested and stripped of its leaves. Its juice is then extracted from the canes (usually by crushing or mashing), boiled until it has reached the appropriate consistency, and processed to extract the sugar. The results of this first boiling and processing is first molasses, which has the highest sugar content because comparatively little sugar has been extracted from the juice. Second molasses is created from a second boiling and sugar extraction, and has a slight bitter tinge to its taste. Further rounds of processing and boiling yield the dark blackstrap molasses, which is the most nutritionally valuable, and thus often sold as a health supplement, as well as being used in the manufacture of cattle feed, and for other industrial uses.

Fig. 1.3 The Sugar Cane Plant

Harvesting

Harvesting is carried out using special sugar Beet harvesters. These machines lift the plants from the ground, remove the tops and clean and convey the roots to a storage hopper or directly to a trailer being driven alongside. Sugar Beet yields on average, 40 tonnes of roots and 25-30 tonnes of tops per ha.

Fig. 1.4 Section through a Beet Chopper Harvestor

Typical yields of Sugar Cane are generally around 40-50 tonnes of Cane per hectare. Harvesting the Sugar Cane crop is different to the harvest of Sugar Beet crops. The crop is harvested straight off the surface whereas Sugar Beet is plucked straight out of the ground. The biggest challenge for the industry has been to become internationally competitive against low-cost countries like Brazil, rationalisation has seen changes to sugar marketing and hundreds of farmers have left the industry. But at least cane growers have a positive outlook to undertake further reform.(3)

Fig 1.5. A crop of Sugar Cane being Harvested

Payment

Farmers are payed by Sugar factories on the basis of (a) weight of washed roots and (b) sugar content. The price per tonne is based on a sugar content of 16%. Bonuses and reductions are made for sugar contents above or below this value.

History

Molasses has been imported into the United States from the CaribbeanIslands since the time of the early colonists. It was the most popular sweetener used until the late 19th century since it was much more affordable than refined sugar, which was very expensive at that time.

Blackstrap molasses gained in popularity in the mid-20th century with the advent of the health food movement. Today, the largest producers of molasses are India, Brazil, Taiwan, Thailand, the Philippines and the United States.

Recently the E.U commissioner for agriculture Peter Mandelson has been trying to force reforms of Sugar Beet production in Europe. At present our minister for Agriculture, Minister Coughlan has been negotiating with the 11 States which are currently opposed to the reforms. It was the same principle that applied to the Milk Quota across countries like Canada but now in the sugar case, Europe has taken a much tougher line with its sugar producers than Canada has with its dairy farmers. Canada simply reduced the quota but maintained the price. Europe is effectively forcing whole regions out of sugar production and bringing its price down much nearer to that of sugar cane. For the rest of the tillage sector, Europe is already at or below world prices according to an article in the December 3rd edition of the Farmers Journal.

The EU are now looking for more efficient and cost effective ways of producing sugar which in time will wipe out the whole Beet industry in Ireland and Europe, and may eventually lead to global wipeout of the whole Sugar Beet industry.

Boston Molasses Flood.

Other catastrophes destroyed more houses and killed more people. 21 dead people (choked or crushed) and one million dollar damage to property- that is peanuts in the registration of world- shaking adversities. But, in so far asaesthetics are concerned, it can hardly be outdone: Bostons big molasses flood.

It happened on the 15th of January 1919. A big steel tank (15 m high and 27m diameter) standing in the harbor of Boston.

Almost 9 million litre raw molasses were waiting to be decanted.

Around lunchtime a deep flicking bang was hear- the bottom plate of the molasses tank burst.

Steel anchors left their anchorages, more plates got blown off and a huge plethora of brown, tenacious molasses poured out from the tank.

The molasses made its way into town. It ran through the streets at an estimated 35 MPH (60 km/h) A six meter high molasses wave wallowed through the harbor of Boston towards a residential area.

Things that were in the way of the wave, people, railwaywagons, horse carts got cleared away.

The stream rooted out foundations of wood houses and pushed them away. Doors and windows of more stable built houses got pushed in, basements and floors got filled up metres high with the sticky pulp. Who was not able to run away fast enough got sucked into the pulp.

Passersby, who helped the unlucky stuck people, got sucked to the “molasses covered victims” themselves and got roped in the stream. Who wanted to wipe off the molasses on the body by hands made everything worst.

Also, the local fire brigade did not have any miracle cure against the molasses ready, they got stuck like everybody else.

After three hours the stream stopped moving.

Those who could be rescued from the waist-high molasses, had to be cut out of the solidified clothes outright.

Any hopelessly covered horses got shoot dead.

The clean up took months. The whole harbor smelled after molasses and fouling cadavers for months.

Molasses had to be pumped out from houses. Walls and streets got hosed down from molasses.

After recovering from the fright people asked themselves how it came that the accident occurred? First of all people thought the molasses could have exploded due to natural reasons.

After six years of in depth analysis experts had an answer- highly unpleasant for the company that was producing the tank. For the building of the tank too thin steel plates were apparently used, that was less expensive. Nobody ever verified the plans or even the tank itself, and nobody ever heard from double walled security tanks since then. REF 29

Figure 2.The Boston Molasses Disaster

Silage Preservation - (Biochemical Processes Involved)

When freshly cut green vegetation is made into a heap, it continues to respire until all the oxygen available is used up. Respiration involves oxidation of carbohydrates to carbon dioxide which means a loss of food value in the vegetation. Thus, as much of the air as possible should be squeezed out of the vegetation. This is done by rolling the silage heap with a tractor. A polythene sheet of appropriate size is pulled tightly over the heap of silage to complete the sealing. When the oxygen is used up and the environment anaerobic, bacteria present on the vegetation begin to cause fermentation, which is the conversion of carbohydrate to organic acids (Lactic Acid). This continues until the pH falls to a certain level at which all microbial activity is inhibited and the material is “Pickled” or preserved. This is known as controlled fermentation through anaerobic respiration.(2)

When the concentration of carbohydrates in the vegetation is high, the bacteria which control the fermentation process are Lacto-bacillus and Streptococcus species. The acid produced is Lactic Acid. Lactic Acid Silage is palatable to stock, highly nutritious and can be kept safely for years provided air is excluded from it. Packing forage quickly and tightly helps to eliminate residual oxygen. The low pH stops plant enzymatic activity and further microbial metabolism which preserves the forage as silage assuming that oxygen is not allowed to penetrate the mass as Breen and Mullen state in their 1992 edition of Agricultural Science.(2)

If, on the other hand, the concentration of carbohydrates is low, fermentation is controlled by clostridium which leads to the formation of Butyric Acid. Butyric Acid silage is unpalatable to stock, less nutritious than lactic acid silage and far less stable, lasting only a few months.

Advantages of Including Molasses In Animal Feeds:

It is frequently claimed that small amounts of molasses in a roughage-based diet stimulate rumen fermentation. The most appropriate role for small amounts of molasses in ruminant diets is as a vehicle for other nutrients (e.g. urea and minerals). A drought feeding strategy based on the use of liquid molasses supplements containing from 8 to 10 percent urea is now an established practice in Australia (Nicol et al., 1984) and has been introduced sucessfully in Africa (Preston and Leng, 1986).(11)

The incorporation of urea and other nutrients in molasses-based (multi-nutritional) blocks promises to be an even more attractive technology, especially for smallholder-village farmers, for supplementation of locally available crop residues which are of low digestibility and also deficient in fermentable nitrogen (Leng and Preston, 1984; Sansoucy et al., 1986).(11)

Molasses can improve the taste of a food simply by having traces in the solution. It reduces the dust element in the food as well because of its stickiness. Dust may also result in feed wastage. Literature reports have shown that molasses practically eliminated 10% all dust and eliminated 30% fine particles. It is used for pelleting feeds for poultry and farm animals. The cost of molasses is outweighed in the long run when you look at the returns and profits.

Nutritional Uses of Molasses In The Diet

Molasses may be fed to livestock in several ways such as molassed meal, molasses blocks, and liquid form to provide energy directly or be used as a carrier for non-protein nitrogen, vitamins and minerals as well as medicinal compounds.

Molasses Blocks- While the formulations were being tested for setting and hardness, they were also fed to animals. When placed in feed troughs, animals had a tendency to move the blocks about and at times to bite off big chunks.

Treacle Cakes- Treacle is a British term, a generic word for any syrup made in the process of refining sugar cane and it can range from very light to very dark. However, when used in cooking, treacle has come to mean the equivalent of dark molasses.

Molasses- A renewable Fuel Feedstock

With the inevitable depletion of the world's petroleum supply, there has been an increasing worldwide interest in alternative, non-petroleum-based sources of energy. A growing source of transportation fuel worldwide is fermentation derived bio-ethanol. As well as reducing green-house gases, bio-ethanol produces less harmful emissions during combustion than its fossil fuel equivalents. Bio-ethanol is produced from a wide variety of raw materials – including cornstarch, sugar cane and lingo-cellulosic waste materials. The main cost element in bio-ethanol production is the feedstock. The use of alternative types of biomass as a source of carbohydrates for fermentation to ethanol has been studied by many investigators worldwide. Potential cheap feedstocks include lingo-cellulosic biomass from urban and industrial waste and from wood/agricultural residues. Researchers at the Institute of Technology Carlow have investigated the conversion of a variety of waste materials to ethanol – including grasses, cereal straws, newspaper and waste office paper. This research has now been expanded to include sugar processing waste.
1.34 million tonnes of sugar beet are grown in Ireland each year by 3,700 growers based mainly in the southeast of the country. The sugar beet is processed at two plants, one in Carlow and one in Mallow, which yields 200,000 tonnes of sugar. The main by-products of sugar processing are molasses and sugar beet pulp. (8) The Carlow factory produces 25,000 tonnes of molasses and 80,000 tonnes of sugar beet pulp annually. Molasses and pulp are currently used as animal feed. However, as pulp and the molasses contain substantial amounts of carbohydrates, they have potential as a raw material for the production of fuel ethanol or bio-ethanol. Molasses contains 50% sucrose, with smaller amounts of fructose and glucose. Sugar beet pulp contains approximately 30% cellulose, 30% hemi-cellulose, and 30% pectin.
The research at Carlow is concentrating on the enzymatic hydrolysis of the sugar beet pulp to its constituent monomeric sugars – which include glucose, fructose, mannose, galactose, xylose and arabinose. While technology for fermentation of single sugars (particularly glucose) is very well developed, the fermentation of complex mixtures of sugars which include pentoses is not. The use of unconventional fermenting microorganisms to maximize ethanol production is being investigated. The ultimate aim is to work towards the development of new microbial strains with improved properties for the conversion of such waste-derived sugar hydrolysates to ethanol.