Biogas Production: Family Economic Empowerment Opportunities

Vincent N. ~gbogo'* and Ifeoma E. ~ b a e ~ i ~ ' ~ e ~ a r t m e n t of Microbiology, 2~epartment of Food Science and Technology,

University of Nigeria, Nsukka, Nigeria.

Abstract

The ever-continuing increase in the prizes of petroleum products, especially kerosene, the

socio-economic implications and their impact on the environment makes imperative the 0

search for efficient alternatives. Methane can be produced by anaerobic digestion of

biomaterials. This paper proposes biogas production as a biotechnological and sustainable

means of ensuring soil renewal, environmental protection, hygienic cooking, and economic

enlpowernlent of fhrmers and their families. We detail how to build a biogas unit and make

biogas from waste materials -animal manure or plant material, and explore opportunities and

prospects for biogas-driven family economic empowerment in Nigeria.

*Corresponding author; e-mail: nnamdiva@yahoo.co.uk, phone: 4-2348036922 106

Paper prescntcd at tltc 7'' Annual National Conference of the Home Economics Rescarch Association of Nilyria (HEKAN), at thc Universily of Nigcria, Nsukka; Scp. 6-9, 2006.

Poverty-related problems are not in any way new in Nigeria. Worse still they have become

increasingly complex and intractable in the last decades, and according to World Banks

reports, in 1999, Nigeria's Human Development Index (HDI) was only 0.146 with nearly

70% of the country's population of about 150 million living below the poverty line

(Omaliko, 2006), and the burden has over the years been borne by family units. Farmers and

their families always look for ways to make their lives better. In this paper, we propose

biogas production as a biotechnological and sustainable means of ensuring soil renewal,

environmental protection, hygienic cooking, and economic empowerment of farmers and

their families. The process is based on a waste to wealth concept that sees rubbish differently:

not as a tiresome waste of space, but as where there are economic opportunities.

One of the salutary results of increased oil prices during the last three decades was a greater

interest in non-conventional sources of energy. India and China, both pioneers in production

of biomass energy, have accelerated diffusion of biogas digesters in their rural areas to

relieve the crisis in cooking energy (Rao, 1987). This is not so with Nigeria. And with the

continued rise in the prices of petroleum products, especially kerosene it is imperative to

search for efficient alternatives. One way farmers' families can make their lives better is to

make their own fi~el gas, which they can use for cooking (NAS, 1979; Doelle, 1996; Brown,

2006).

The nature and mechanism of biogas production

The term biogas refers to he1 gas, made from animal manure or from plant materials or from

a mixture of boih. Biogas is a mixture of lots of methane (CHd), the active gas (SO-70%))

carbon dioxide (COz), 30-40%, hydrogen (Hz), 5-1O?/o, and nitrogen (N2), 1-2%, with traces

of hydrogen sulphide (H2S), ammonia (NH~), among others (Table 1). Biogas burns very

well (with a clear blue flame without giving out smoke) and is generated when bacteria

degrade biological material in the absence of oxygen, in a process known as anaerobic

digestion (Anon., 2003; Harris, 2006). Its flame temperature is up to 800 'C and it has a

calorific value of 5650 Kcal per cubic meter of gas (Anon., 2003).

Papcr prcscnted at tllc 7"' Annual National Conference of the Hornc Economics Research Association of Nigeria (HERAN), at Ll~c University of Nigeria, Nsukka; Sep. 6-9,2006.

Anaerobic digestion (generally perceived as a waste treatment technology) is basically a

simple process carried out in a number of steps that can use almost any organic material as a

substrate - it occurs in digestive systems, marshes, rubbish dumps, septic tanks and the Arctic

Tundra. It can produce biogasfrom mainly manure (Table 2) and crop

residues (Hills and Roberts 1980). The process of anaerobic digestion consists of three steps:

1 .The first step is the hydrolytic decomposition (Table 1) of plant or animal matter. 'This

step breaks dawn the organic material to usable-sized molecules such as sugar

2.The second step is the conversion of decomposed matter to organic acids.

3.And finally, the acids are converted to methane gas.

Digestion temperature affects the rate of digestion and should be maintained in the range (35

to 40 degrees Celsius) with an optimum of 37 degrees Celsius.

Paper prcsented at the 7'' Annual National Conference of the Home Economics Rcscarcll Association of Nigeria (HERAN), at the University oTNigcria, Nsukka; Sep. 6-9,2006.

Biogas is typically 50 to 70 percent pure methane. As methane is very hard to compress, it is

best used as stationary fhel, rather than mobile fuel. It takes a lot of energy to compress the

gas (this energy is usually just wasted), and as well, you have the hazard of high pressure. A

variable-volume storage (flexible bag or floating drum are the two main variants) is much

easier and cheaper to arrange than high-pressure cylinders, regulators and compressors

(I-Iarris, 2006). With small biogas units as discussed in this paper, the gas is channelled

directly from the production plant to burners by the aid of gas lines equipped with airtight

valves. The by-products are also usefbl as fertilizers and soil improvers or composts if the

feedstock is not contaminated (Anon., 2003). #

Global production & utilization of biogas

Biogas has provided an economically viable and sustainable means of meeting the thermal

energy needs in China (7.5 million), India (3 million) and Nepal, where over 37 000 biogas

digesters were installed from 1992 to 1998 (Doelle, 1998). Their use is not limited to these

countries, but extends throughout the developing world. More recently, developed countries

have been making increasing use of gas generated from both wastewater and landfill sites.

The he1 produced may be used for direct firing of boilers or to fie1 a CHP (combined heat

and power) plant. Alternatively, the gas can be upgraded by extracting the trace gases and

C02 to produce a vehicle-grade fie1 (Harris, 2006).

The most recent Mons anaerobic digestion plant in Belgium can handle 58,000 tonnes of

waste per year. A plant in Freiburg in Germany processes 36,000 tonnes of waste per year

producing 3 million cubic meters of gas and 15,000 tonnes of compost (Harris, 2006). In both

India and China, biogas is regarded as a means of ensuring soil renewal, environmental

protection, and hygienic cooking. Today, over 85 per cent of the Indian biogas plants set up

under the National Programme for Biogas Development (NPBD) launched in 1980 are in use.

Both the Indian and Chinese biogas plants seem to be moving towards the same goal - large-

scale popularization of bio-energy through ,decentralized, egalitarian strategy and

introduction of inexpensive but technologically efficient digesters (Rao, 1987).

For six years La Compagnie Malienne de Developpement des Textiles (the textile

development company of Mali) popularised the use of biogas in southern Mali. The

Paper prcsentcd at lhe 7"' Annual Natior~ll Conicrcncc of thc Homc Economics R c s ~ ~ r c h Associaliotl of Nigeria (HERAN), at the Uilivcrsily of Nigcria, Nsukka; Sep. 6-9, 2006.

installations were designed along the lines of a Chinese model and more than 60 are still

functioning today. The success of the community level biogas enterprises depends on local

organizing ability but fbrther research is needed .before domestic systems are introduced

(Anon., 1995).

The Nigerian Situation: prospects and problems

With a warm, stable climate and easy availability of plant materials and animal wastes (cow

dung, poultry droppings, pig excreta among others) occasioned by the curreit positive shift

in agricultural policies of government, Nigeria is in an advantageous position for adopting

and popularizing biogas. At present, much of the dung produced by about millions of herds

of cattle in Nigeria is either wastin2 or burnt away as wastehl cooking hel. Assuming an

average production of 10 kg of dung per animal per day and a collection rate of 60 per cent,

the amount of dung available in the country in a year may work out to about 300 million

tons, which could generate a staggering millions of tons of humus-rich manure. As it is, 30

million m b f biogas equals 20 million tons of kerosene oil, nearly three times the annual

consumption of the commodity in the country (Anon., 2003).

Diogas is not popular in Nigeria. Much of the materials available on biogas in Nigeria are

rcports of scientific researches into the technical aspects and basic factors of biogas

production, especia.lly on raw materials (Garba and Ojukwu, 1998; Zuru ef al., 1998;

Adelekan, 2002; Ezeonu el a/., 2002). However, the federal government has in 2001

established the National Biotechnological Development Agency (NABDA) that is mandated

among others to develop conservation strategies to promote sustainable utilization of

Nigeria's hugc biological resources and to facilitate the speedy evaluation and utilization of

the processes and products of biotechnology while ensuring environment stewardship

(Omaliko, 2006). Recently biogas production is beginning to catch attention, here in Nigeria.

At Ibadan, a local NGO and a community-based organization has joined with technology

innovators from 'Thailand and the Sustainable Ibadan Project, Nigeria (UN-HABITAT

Programme) to install a biogas plant that will run on abattoir effluents to create a source of

Paper prescnlcd at the 7Ih Atuu~al National Confcrcncc of Ulc Home Ecorlonlics Research Association of Nigeria (HERAN), at the University of Nigeria, Nsukka; Sep. 6-9, 2006.

domestic energy, abate pollution and mitigate greenhouse gas emissions. The biogas plant is

expected to return a profit on the initial investment within three years and will have a productive

life of fifteen years (GNEEDR, 2006). The proposed biogas plant, the initiators claim has

tremendous potential to be replicated in other urban'areas of Nigeria, across Africa, and beyond.

According to the Ministry of Environment, the federal government is to construct two pilot

biogas plants for the conversion of abattoir wastes to biogas and organic fertilizer in

Oyo and Kano states. This project to implemented through public1 private partnership, in

addition to the production of a cheap source of domestic cooking gas and organic fertilizer, is

expected to generate employment *

It is known that health is wealth and the link between poverty and ill health has long been

established. Biogas production and utilization will turn environmental and human health

hazards into valuabie energy resource and revenue source. A supply of piped gas for cooking

will reduce deforestation and end, for women, the daily drudgery of collecting firewood.

Nigeria's women will have more leisure time than ever before. The introduction of biogas

stoves will reduce or eliminate health hazards (like respiratory disorders affecting women

and their children) associated with wood fires. The hygienic state of settlements will also be

improved when sewage. Channelling slaughterhouse wastes, a major sources of local water

pollution and greenhouse gas emission into biogas production will improve lives by

providing cheap, clean burning domestic gas for urban poor families and cheap organic

fertilizers to low-income farmers. Biogas production and utilization will destroy methane, the

highly destructive greenhouse gas, so it does not go into the environment and contribute to

global warming. Besides supply problems, the environmental impact of sources of energy

based on fossil he1 is rapidly generating great concern as the impact of increasing levels of

"greenhouse gases" like carbon dioxide (COz) on the global weather patterns is becoming

more apparent. Environmentally, biomass has some advantages over fossil fuels such as coal

and petroleum. Growing plants for use as biomass hels may also help keep global warming

in check. That's because plants remove carbon dioxide--one of the greenhouse gases-from the

atmosphere when I hey grow.

Paper presented at thc 7tt' Annuid Nalional Conference of thc HOIW Economics Rescarch AssociaLion of Nigcria (HERAN), at the University of Nigeria, Nsukb; Sep. 6-9,2006,

On a large scale, power from biomass gasifiers, will make irrigation possible and contribute

to the expansion of agricultural activities with the result that young men, many of whom used

to be obliged to leave the village to seek work elsewhere, will now be able to find worthwhile

jobs in their own village. The adoption of biogas production in Nigeria and its inclusion in

the household's activities more than doubles household income; the increased benefits from

the added activity, and the system interactions will enhance earnings from livestock-raising.

Biogas production and utilization will also boost livestock keeping in Nigeria and help to

meet the ever-growing demand for meat in urban Africa. The result would be more income

for families. 0

However, there are problems. There is always a strong inertia against change in every human

society. The current policy of Government, which prioritizes petroleum products, does not

favour the adoption of alternative and renewable energy sources.

How to build a sm.all biogas unit and make your own biogas

Biogas plants are an element of a waste-recycling concept in which a part of the organic

matter is converted into energy during a process of fermentation. They are structures in

which raw materials are fed and digested and biogas is produced, stored and conveyed to the

end-use points, and at the present, there are five types of biogas plants by constructional

features: floating drum, fixed dome or drum-less, tunnel, bag and split design (Anon., 2003).

Biomass fuels include urban refuse, industrial waste, agricultural and animal residues,

sewage sludge, and energy crops. When animal manure or plant materials rot they give off

gas. You collect this gas as it is made when you make biogas. Anaerobic fermentation

(fermentation that occurs without the presence of oxygen) is widely used and is a reliable

method for producing biogas. It is not easy to build a biogas unit. When you begin you will

have to spend a lot of time and work very hard. It may also cost you money. You must be

sure that building a biogas unit will be a good way to use your time and money. You' will

need a good place to put your biogas unit. Biogas is produced best at a temperature between

32 and 37°C. If you live in a very hot place, put your unit out of the sun, in the shade or

under trees to keep it getting too hot. In not warm places, put the unit in the sun.

Paper presented at Ihc 7* Annual National Conference of the Home Economics Research Association of Nigcria (HERAN), at the University of Nigeria, Nsukka; Sep. 6-9, 2006.

Here, we describe how to build a floating drum biogas plant (Anon., 2000). You will need oil

drums, pipe, valves, a gas line and sealing materials to build a biogas unit. You will also need

a good supply of animal manure or plant material, and advice from your extension officer. A

biogas unit should be: at least 10 metres from your home so that when you put waste into your

unit it will not be too close to where you and your family live and cook your meals. Begin by

building a small unit. This will cost less to build and it will be easier to run. You can build a

small biogas unit fiom two oil drums. You will need

an oil drum of about 200 litres, to hold the waste

an oil drum of abollt 120 litres, to collect the gas

a piece of pipe about 10 centimetres long and about 2 centimetres in diametir, for the

gas outlet

a valve to fit the gas outlet

at least 10 metres of rubber or plastic tube about 2 centimetres in diameter, for the gas

line

Figure 1 : Floating drum biogas plant

Paper prcsented at Ilic 7Ih Annual National Conference of lhc Homc Econonlics Rcsearch Association of Nigeria (HERAN), at the University of Nigcria, Nsukka; Sep. 6-9,2006.

The bottom part of the unit, which holds the waste mixture, is made from the bigger drum.

The top part of the unit, which holds the gas, is made from the smaller drum, which you put

inside the bigger drum. You will need a threaded hole in the top of the smaller drum for the

gas outlet. Screw in outlet and attach an airtight valve to its top

Straw that is mixed with manure, which you may have where'you keep your pigs or chickens,

is usually a good mixture of animal manure and plant material for making biogas. When you

first begin, it is best to use only animal manure or a mixture of animal manure and very little #

plant material. Later when you have learned more about how your biogas unit works, you can

use more plant mxterials. Mix the materials with water (a bucket of water per bucket of

animal manure or plant material).

About two months before you are ready to use your biogas unit for the first time, put 2 litres

of animal manure and 2 litres of water in a bucket and mix well. We call this mixture a

starter. A starter helps the biogas unit to make gas sooner. Now you are ready to put the

waste into your biogas unit. Put the large drum open end up where you want the unit to be.

Put the small drurn next to it with the gas outlet up. Now put the waste and water (equal

volumes) you are going to use into the large drum and stir it well. Stir the starter you have

made into the waste mixture in the large drum.'Then, open the valve to let out the air and

push the small dnrm down into the waste mixture until it touches the bottom of the large

drum.

You can tell that the waste mixture in your simple biogas unit has begun to rot and make gas

when the small drum begins to rise. This means that gas is being collected. It may take up to

three weeks or even a month for the waste in your biogas unit to start making gas. ARer. that,

gas will be made for about eight weeks. Do not burn the first gas that is made. It may have air

in it and could explode. After all the gas has been made, take the unit apart and empty out the

fertilizer. Keep about 4 litres of the fertilizer to be used as a starter for the next time.

Paper prcscnled a1 1 1 ~ : 7h Annual National Conference of Ll~c Home Economics Research Association of Nigeria (HERAN), at the University of Nigeria, NsuMta; Sep. 6-9,2006.

The best way to use the biogas that you make with your small biogas unit is for cooking.

When your unit is working well, it will make enough gas every day to cook your evening

meal. You can use biogas with almost any ordinary gas- burner, if you adjust the burner so

that the right amount of air is mixed with the biogas. You can spread this new fertilizer an

your fields to help !{our plants grow well or sell to make money. There are still other ways to

make more biogas. You can build an improved small unit or you can build a different kind of

unit that is bigger and better and will give more biogas.

Conclusions and Recommendations 0

The presented strategy for economic empowerment of families has as its core unit the

biogas production through anaerobic digestion that will also remove the ever-increasing

health and environmental hazards in developing countries. It is against a background of the

prospects and problems of biogas production in Nigeria already discussed that we

recommend as follows:

- An immediate shift in governmental policies to favour the adoption and

popularization of biogas and other renewable energies in Nigeria.

- Introduction of a biogas programme, which must not be imposed from above without

active and meaningful participation of the users. The strategy will lead to the

evolution of inexpensive and locally adaptable technology.

- Provision of subsidies for to families and communities wanting to build and run

biogas production plants.

- Training and deployment of extension officers that will provide farmers and their

families with technical know-how on building and managing biogas plants

- A complete re-structuring of the agricultural systems would be necessary: indoor

stabling of dairy cows and a regular production of fodder grass would have to be

introduced.

Papcr presented at thc 7" Annual National Conference of thc Home Economics Rescarch Association of Nigeria (HERAN), a1 Ihc University of Nigeria, Nsukka; Scp. 6-9,2006.

References

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Anonymous (2000). Better Farming Series 3 1. Biogas: what it is; how it is made; how to use it.Available in Humanity Development Library 2.2 November, 2000 : http://localhost/cgi- bin/gw?e=q 1 clOhome-hdl-2l-B.112.3.3-11-100-20-0&q=biogas%20unit&a=t&d=B. 1 12.3.3

Anonymous (2003). Biogas plants. Available at: file://A:\bioaas. htm

Brown, V.J. (2006). Biogas: a bright idea for Africa. Envirorimenfal Health I'ers/xxfives 114 (5): A3OO-AgO3. Doelle H W (1989) Socio-ecological biotechnology concepts for developing countries. MIRCEN .Jorrr~zal A p e d M i c r o i o l o Hiofechnology, 5:391-4 10

Doelle H W (1996) Joint venture capital investment for clean technologies and their problems in developing countries. World Jmrrral Microbiology Riofechnology 12:445-450

Doelle, H.W. (1991%) Socio-economic microbial process strategies for a sustainable development using environmentally clean technologies: Sagopalm a renewable resource. Livesfock Research. for Rtrral L)eveloprnenf 10 ( 1 ).

Ezeonu F.C., Udedi, F.C., Okaka, A.N.C. and Okonkwo, C.J. (2002). Studies on brewers spent grains (BSG:) biomethanation: I- optimal conditions for digestion. Nigerian Jo~rrnal of I~erre~vable Energy 10 (1&2):53-57.

Fontenot, J.P. and Ross, I.J. (1980). Animal waste utilization In Livestock Waste: A Renewable Resource. Proceedings ofthe 4th International ,Yymposizrm on Liveslock Wades - 1980. pp. 4-10.

Garba, B. and Ojukwu, U.P. (1 998). Biodegradation of water hyacinth (Eichhorriia crassilxs) as an alternative source of firel: a review. Nigerian Journal ofRenewnble Energy 6 (1&2): 12-15.

?2pcr presented at t l~c 7'' Annual National Conference of the Home Economics Research Association of Nigcria (HERAN), d thc University of Nigeria, Nsukka; Scp. 6-9,2006.

GNEEDR (2006). Cows to Kilowatts. Global Network for Environment and Economic Development Research, Nigeria

Harris, P. (2006). An Introduction to BIOGAS. Available at: file:///Dl/Documents and SettingdBeginners Guide to BIOGAS-Paul Harris,The University of Ade1aide.htm

Hills, D.J. and Roberts, D.W. (1980). Methane gas production from dairy-manure and field- crop residues. 111 Livestock Waste: A Renewable Resource. Proceedings qf /he 4th Iitte~~rtafioiml Sympcair~n? ot1 /,ivesfock Wakvfes -- / 980. pp. 92-95.

NAS (National Academy of Sciences) (1979). Microbial processes: prontisirg technologies .for developiiig collm/r-ies. Washington, D,C: National Academy of Sciences-National Research Council. pp. 107-138.

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Rao, R. (1987). India, China seek improved efficiency in biogas schemes CERES No. 119 20 ( 5 ) - September-October 1987.

Zuru, A.A., Saidu H., Odum, E.A. and Onuorah, O.A. (1998). Compartive study of biogas production from hores, goat and sheep dungs. Nigerian Jormtal of Renewable E ~ ~ e r g y 6 (1&2): 43-47.

Paper presented at tllc 7"' Annual National Conference of tlle Home Economics Research Association of Nigeria (HERAN), at the University of Nigeria, Nsukka; Scp. 6-9, 2006.

Biotcchnological Approaches to Cassava Wnsk Managenlent

Vincent N. ~ ~ b o ~ u * ' , Ifcoma I. h'lbaeyi2, Cllrisli~n U. lrocgbu' and ,J. C. ~ ~ u r n v a m b n ~ '

l~>cpartmc~lt o f Microbiology, Z~cpa~-trncnt of Food Scirlicc m d TCCII I IOI I )~~ , 31)cl~nrt~l~~nt of Civil Engiuccri~~g, University of Nigcl-in. Nsukk:i. Nigcrin.

111 Nigcrin, cassava has conic to bc seen as a crop c~~lowct l wit11 special capacity to contribute

to thc dcvcloplncllt of food scc~lrity n~ld pove~ ty alleviation i l l tlic cor~titry. Co~lseq~~cnlly, i t has

~cccn[ly sllilicct liori~ just a s t q ~ l c crop to a cash crop. I j i ~ l I r ~ ~ o ~ l c l 111c aplwrcrlt cco~lo~~t ic gain

lics waste gcticrat~on. 'I'his p a p - proposes biotccIlrlologic:~l ;~ppruacl~cs as thc mcnlls to a

sustainnble and eCfcc1ii.e r~lrtnagernent or cassava wastc. Wc discuss the ~ialure 2nd ctrccts of

cassava wastcs and :~iotechnologicat processes (li kc nnncrobic oxidatio~l anti solid-state

ferrncntnlio~l) that can scrve a dual jmposc ol' \\laste\vnter/~.clirsc tlisposd ant1 production of

ilscfi~l prodlrcts. I'roposctl solutio~is for. ~ i~n~ing i~ lg c:lssnva n l i l l \v:lstcnrnter inclutle building

community stabili~ation ponds and usc thc cf'llucnts as illig2tion \vatcr 011 various crop liclds.

Proposals to be irwestigated lor managing the solid waste include PI-oduction of ani~nal feeds,

biofilels, luannrc and otllcr. iltnovations, sr~cll us usillg cassava solid ivastc to raise wolnls for

pig fccd.

Kcy worcls: cassava wastcs, allrlcrubic oxitiatio~i, solitl-state l ' c ~ ~ l ~ c ~ ~ l n t i o ~ i , I)ioli~cls.

'Co~,~.cxl)o~ltli~~g nutlior: pllonc, 1 2138036022 1 06: 1 ;-!llai I : I ~ I ~ ; I I I I ( ~ ~ I ~ ; I ( ( $ ~ : I ~ I ~ ~ . c ~ . ~ I ~

1.0 Introduction

In the trdpics, cassava (ilatriltot esctrlertr~~) is a unique renewable resource. Africa produced

101.6 million lnetric tonnes of cassava in' 2003 innltir~g i l Lllc 111ost important root crop

(FAQSI'AI' cl:~ta. 2'004) ard a n~ i~ jo r souscc of' tlictar-j. calorics. ' I Ilc ir~iportarice of cassava to

t l~c livclil~oods of many millions of poor pcoplc has tiinclc tlie c t r i~ r r~ :oc i~~~ CI u ~ g c t for

interventions. NEI'AD lias adoptcd thc slogail 01' "Cassava: A l'owcrf'ul l'overty Fighter in

Africa" for its I'm Africa11 Cassava I~iitiative (NIlI'AD, 2004). 111 Nigeria, cassava is viewctl as

a crop grcatly entlowcd will1 special capacity to contribute to the dcvclolm~er~t of rood sccurity

and povcrty alleviation in the cor111try (Orndiko, 2000)

l'lie potential of'tlic crop is largc bccnusc i t offers tlic clmpcst svtrrce of liwtl calorics and tllc

highest yield pcr unit area. I t also has ~nultiplc rolcs as a G~ini~ic Icsclve, food nntl cash crop,

industrial raw material n n t l livcslock L'cctl. Glol)i~lly, cassava i s Iwing r~tilizecl cxtclisi~dy for

industrial protirlction o r paper, plywood, adliesivcs, S W C ~ ~ C I I C ~ S , 1110110sodiilrn glutamte,

alcohol, amino acids, ctc. (I'oonsook, 1000; C)glwr~r~n, 2005). Cassava lias also rccently

bccomc significant in cllvirolmc~itol ~noringcriicri~ a ~ d pollutio~~ control: two cutrcl)rcr~ct~rial

I'hai scientists have come up with an edible answer to packaging food. t3ioclegradablc trays and

plates lnadc from cassava arc helping to rcducc waste, whicli profits 1~0th thelnsclves ant1 the

elivil.onlnent (CGC, 2002).

A major problc~ii with cassava is its cyaiiidc c.o~itcli[. whicl~ occurs i l l tlic 1i)r111 01' cjwlitlc

glycosiclcs i.c, linaniarin (93%)) aid lotaustrnlir~ (7%) ard car] IIC easily libcratccl by the

cnzyme, !inamerase (Bcngtsson and 'l'riet, 1994). Cyanitic is highly toxic to most urganisms,

affecting particularly the ecnlral ncl-vous system (CNS). This is bccnirsc i t f o r m extrerncly

s t a l k colnplcscs with tlalisitio~i ~nctnls tli;lt n c cssctilial l i w pr.ok!iri lil~lctiw ( i . ~ . ir011 i l l

cylocllromc oxitlase) thus ~ i~ak ing csscnlid r ~ ~ c t d s u~~avail:hlc to organisms (dLuque-Allnago

et ol., 2005). Studies havc show tl~at in Africa, Malaysia and South Amcrica, a cliel with large

amounts of cassava can cnusc chronic effect in the thyroid gland and on the CNS (Ekpechi,

1973; Ramirez, 1982).

' l ' l~c water pollution problc~n is critical. I,ow concentrations of lcss than 0.3mgJl of cyanide

may result in 111;1ssi~c fish kills. Again tlic W;ISLCW;IIC~ is Iiiglily acidic ( S ~ I ~ C ~ ~ I I ~ C S 2s low i lS pI.1

2.6 and a combined wastcwatcr pl I has I m n I-cporkd as ranging bclcvecn pH 3.8 and 5.2), and

tllc low pl1 may harm aquatic orgnnis~iis a d prcvc~~t self-purification of the rccciving water

kody. Therc arc few sl~ltlics i~lvcstipt i l ig the cf'lbcl o f cassa\Ia processing contaniinnting thc

gl-ound-\v,atcr srrpply. 1:roni tllosc u~iclcrtakcn. c\litlcr~cc is rlol concl~lsivc. Co~itaniination is

most likely lo occur i l l rcgif)~ls \\;llcr.c a I;~rgc nrlrnlxr ol' ~ I . O C ~ S S O I . S arc c ~ ~ i c e ~ i t r a t c d in a small

gcograpliical area. ,

unn~ixetl, unlmtcd open tank (low ratc digestion) to a mixcci alid licatcd covered tank (reactor),

i~icorpora,ling c~~llcctioli a~icl nlilizalion of ilic gas procluccd. l'ollowed by a secondary digester

!or licluidlsolids scparaiion (Iiigll rate digcslion).

An aliael-obic lagoon is cssc~i~ially a cridc I I I I C ~ I I I I O I I C C I 1111;1crot)ic cligcslcr. l'he lagoon system

is tlic most popular treatmeill system usctl by cassava slarch processors for trcatrnent of

wnstcwate~~. l'llc combined waslcwalcr is 0lic11 collected in a storage pund from wlicrc it is

pi~nipcd ll~rougli a scrcc~i illlo a prc-lrwlrncnI ~)oliti. Alier tliis, llle \vastcwatcr is punipcd

tlisoug11 a scrics 01' t rca t~ i ic~~l po~icis, lllc l i ~ st 2-3 bci~ig a ~ l w o h i c . \~llcsc ~iatural bscakdown

proccsscs succcssivcly dcglaclc organic suhsta~~ccs (IhSilva i111ti Sasso~l. 1089).

In a~iacrobic tligcstion of cassava ~ v a s k , cyuliclc is relcasccl i l l llic li.rliicntalion liquor and then

libcrateel by cnzymalic ant1 no^-cnzytiiatic reactions. 'l'lic I-cniovnl of'cyariidc has bccri shown

lo hc sullicicntly fasl to ~i~aililain n cyanide collccll(s;~lion il l tllc ~.c:lclor. which is lion-

inliibilory for n~clhsnagcnic baclcria ( I Jtlo~~iplioni, IOSO).

I3io!?lni prc)ccsscs used by lllc ilitlustry co~~lprisc clil'lclc~ll c~~g i~~cc rcc l conligi~rntio~~s, sirdl ns

lisctl bed, 111ovilig bcd, Iluiclizctl hcd. rccyclctl bed 311d upflow a~iacsohic sludgc blil~lkct

(IJASD). A11 llicsc ~caclurs can Iio~lcllc loads up lo 20-30 kg ('Ol)/ni3/tlay). All ol' tl~csc

processes rcclirirc n rclntively small rcactor size. md a vxs~ly rctlucctl I-cquircmcnt lbr land and

capital. 'l'llc lbllowing systcnis arc li-cqucnlly iisccl (I>ocl lc. 1080; I>ocllc. 199613)

a. 1;ixcd bcd: (anaerobic liltcr. p;~cl<cd bed lillcr, packed kccl, sul)~iicrgcd filter, stationary fixed

film rcaqlurs). ,'l'lic principle ol' opcratiorl is tliat tlic suppo~ 1 malcriai is also [he surface for

attaclllncnt 01' llic ~nicroorg:~l~isrils anti can act as ail cntriip~ilcnt ~ncchanism Tor unattached

Ilocs. Many sul~p,ort types :11c ~ ~ s c t l , i~icl~~tling t l u ; 1 1 1 ~ , ~)lastic, claj., oystcr sllells, stones.

~ w l y h c r foam. activatcd cxboii a ~ ~ d sand.

b. lhidizixl hccl reactor: In this type ol' reactor nwst ol' tlic bio~ilass is attachcd as films to

small-sized incrt media. 'l'l~c 1)iomass-covc~ed particles :~rc lil'tecl (Iluitlizcd) by the l~igll

vertical vclocily of tlic ilico~i~ing waste. Various support ~ ~ ~ a t c r i a l s arc used, such as sand, PVC,

and granular activatcd caslmll

c. Iipflow anacrobic slutlgc bla~ikel (UASIJ): 'I'l~is typc of rcactor collsists of a dcnsc bed of'

granular sludgc (microorganisnis) placctl in a reactor tliat is tlcsigned to allow upward

~ i i c ~ v c ~ i i c ~ ~ t of l i c l l ~ i c l \v;~slc. \Vxstcivatcr c~ilcsing at t l~c tcactor bottom is tlistsibutcd across t l~e

cross-scction and flows upward Ilirougl~ tlic hctl of' slutlgc granules rctaincd in tlic system.

Sul'ficicnl upflow velwilies arc ~noinlairiccl i l l I I I C reactor to facilitate sluclgc blanket fornlation

and to provide a grcatcr s u r l c c i~rca ('or contact bctwccn sludge granules and

wnstewalci-.

solicl-stare fcnncnlation Iiavc Ixcn dcscribccl ( Ih in i l~a \~ l t o/ trl , / YY3) . Solicl-state l'crriicntr?tion

~wocess, dcli~lcd as thc gro\~tli 01' niicroolga~~is~iis (~i ia inl~. limgi) 011 moist solie1 ~~ia tc r ids in

tlic absence or Ilcc-flowing \vatu, is well aclnptccl aricl chcapcr li)r tllc production o f animal

f ids f'mm cassavn ,wastcs(pccls atid Icnvcs).

can be obtninctl by i i s i ~ ~ g 7i~icl1otic1.11ro sp. by solitl-state Scl.~ncntation. Uclewu alid Musa

(2003) cvaluarctl tlic cf'l'cct ol' t h ~ cc tii l'lkrctit strailis 01' ,4zo/ol~trc~~.r lxictcrir? in solid substrate

krmclitation o n cassava wastc.a~itl co~~clutlccl that botli inculwtio~l and tmctcrial activity are

iristrumcntal in il~cseasing tlic potential prokill, I~cliiiccllulosc ant1 cwrgy contcnt of cassava

wask during solid s u b s h t c Ikrnicntatio~~ ancl the cl'licacy clcj~c~~cls on tllc species of' huctcria

~rscd. Ensiling o f thc solid rcsicluc ol'cnssava processing lo\vcrs the cywide lcvcl to onc thnt is

1io11-toxic, leacis to a rccluction in pl I to 4.0 ant1 allo\vs I:ictic acid to build-up. 'Tl~c prod~icl is

s~~bsequcntly usctl as ani1ii;il I'cccl. (Oriialil<o, 2006).

'I'he ~woductiorl ol'hioli~cls to rqdacc oil ard natr~ral gas is in active tlcvclol~~icrit. Accorrlirig to

tllc [ IS . Ilcpart~iiclit ol' Il~icrgy I~l ' l i~ie~icy ;111d I ~ c ~ i e ~ ~ ~ i ~ I ~ I e I.11crg~1, I~ioli~cIs ci~rrc~itIy povidc

li)r approximately 3 pcrcclit 0 1 ' Ihc IJnitctl Stiitc's told c~lcrgy C ~ I I S I I I I I I ~ ~ ~ ( . ) I I , i111Cl ap1mxi111atcIy

15 pcl.ccnt 01' c~icrgy co l~su l~ lp t io~~ wwltl\viclc (171 1111;wiIy i l l (Ic\.cIopi~~g ~o i~~ l t r i e s ) . \Vitll

continued rcscarcli and tlcvc.lopi~ig tccl~nologics, cassava waste call hc used to producc

biolilcls. cspccially bioys. I\ioga.; is odourlcss and I W I 11s \ \ t i l l 1 clew I J I I K Ilanlc, without givi~ig

out smokc. 11s I l a ~ i c tcnipcr:itutc is up to S O 0 "(' nlid i t I~as u ci~lorilic vnlw ol'5050 Kcal pcr

cubic ~nctcr gas. In Japan, tlic ('assava Wastc to 1:ncrgy p~ujccl, which will conic into hdl-

scale operations in Ilccc~iihcr 2000. will collccr nlctlianc li-0111 orga~iic cflluc~it cliscliargcd lion1

cassava slnrcll I'xtorics, ant1 scll t11c hiog:\s 1 0 lllc lilcto~ ics (AgIx)gi~ ct : \ I . , 2000).

I )ocllc. I I.W. ( l 00017) .Ioir~l t~-n1ui.c cal~ilal i r ivcst~i~c~~l liv c l c a ~ ~ tcclitlologics a~id tllcir ~~rol,>lc~iis i n dcwlopi~ig cou~itr~ics. / l 7 o / . / ( / , / o ~ ~ ~ . ~ ~ ~ ~ 1 I \ / ~ c ~ I ~ o / ) ~ o / o , ~ . ~ ~ I ~ ~ o / ~ ~ ~ ~ / I I I o / o ~ J ~ 12: 445-450.

I'ckrs, I)., Ngai, D.D., An. 1 ) . ' 1 ' . (2001 ), /\gl~o-pl.occssi~~~; Waslc Assesslncnt in l'cri-nt-ban I I N . I r o i c o t 0 0 - 2000; pp. 45 1-457.

Effrcts of sugar level c / ~ d storage period on the yiiulit~ oftnrrtrgo jum. Girgih, A. T.,I)aramola, A.A and .

Kaze, A.S ........................................................................... : .......................................................................... 227

Leve1.y qfheavy metab accumulation in selected biota in evitrtn creek located in Rivers Stute. Oboh, C.A.; '

..... Daka, E.R. and Achinewhu. S.C ........................................................................................................... : 230

Efict of stor~rgc period on proxitnote conip~.si!in:r (rr~rl/iitri~tiotrtrl propcrti~:r ~ ~ t ~ s t r i i ~ / e ~ / / i r l I ~ / i ~ t .soy Iloiir.

Okomwa A.E.ancl . Adenekan.G.1 ........................... ........................................................................... 232

~ r o ~ i c b ~ ambient storuge of tomuto puree, I : Itl/luence of sodium chloritlc urid trricroucro,)hilIii: cotiditiorr

onproduct yuulity. Ariahu,C.C., Ekwuno, C, a11d Girgih, A.7' ..............#................!.................................. 234

Sensory evuluatior! cf fresh .fish pepper soup seusotrcd with burtrburu groutidnut (Vigtru srrt)rerrt~rrcu)

clawudawa.Baritnalaa. 1.S Amadi, E.N Ikharo, E.. Achinewhu S.C and . Mebpa.H.D .................................. 236

~ ~ t i m i s u r i o n ' of the levels of incirrporarion of Afiicun yilm bcan (Sphetrostylis stenocurpu) /lour. into

communifed meat-lypeproduct as an extender. E.B. Banigo .................................. The ef/i?cts,of essenrial 011s from diflerent indigenous spicer on the microbiul stcrbility of smoke-drried ji.~h.

Kiin-Kabari, D,B.; Barimal~a, IS.; Amadi, E.N, and Ach~newhu, S.C ............................ .. .............. 24 I

Efkct of ,sproutirig andpre-gelatirrisation on the compositiotr ofsorghum (Sorghum bicolor L.) Mbaeyi,

1,E. and Onweluzo, J.C .......................................................................................................................... 244

popularly used as maize. Traditionaity, sorghum is processed into fmetltd t&in prridgc

beverage (maltad drinks) and lately popped snack Processes like fermentation, sprouthi and

who do not have mu:& time for f d prepmation. hpmccssing therefore to a convenient

fonn will cncourqe the consumption of these traditiond dishes by such p u p . The

preprocessed products may also be used as a raw material base for the development of other

products. This work w ~ s designed to assess the effkct of sprcuting a d prtgelatinhtion on the

composition and hncti~nal properties of sorghum in relation to its use as a base fix any ofthc

wdxlhional products.

MATERPAIS AND IClETHOD A 600-g weight of sorghum grain (white variety) was clwed; sorted and dividcd into

the prtlons. C)ne third of the grain was spkuted according to EtokAkpm suwi ~almer'; the

second lot was pregelathksd and the untreated portion served as control. The m p k s were

dried, milled and sieved b pass through Imm pore-sized sieve. Chemical analyses were

srunpk. Protein content was lower in the hreated sample, probably due to leaching and

hflrolysis. D i f f m i in ash and fibre contents. between the treatments were not sigdkmt

dllt 95 % c~nfiden:~e limit.. The untreated simples showed higher energy value w0.05) whik

the sprouted sample had relatively low energy. The sprouts would have used up part of the

inhered nutrients. Except the pregeiatinized sample that showed marginally higher

phosphorus content, the preprocessing did no! affect the mineral content (calcium, sodium and

potassium) of the samples. The pregeiatinz.ed samples showed low pH followed by the

sprouted samples. The decrease in pH was attributed to partial hydrolysis caused by the

treatment. Expectedly, dispersions of the treated samples exhibited lower viscosity than the

control. These treatments have been used in increasing the energy density of cereal starch for

use in weaning foods3. The marginally higher bulk density oftbe treated sorghum samples for

use in certain product formulation treatment increased the least gelation concentration by 2 %.

This result is in agreement with literature data4, and sorghum being one of the "waxy" cereals

with high- proportion of mylopectin, exhibits low least gelation concentration. It is evident

from the study that sorghum can be pre-processed by pregslatinization and sprouting without

adversely affecting the composition and fimcttonal properties of the grain.

Tublc 1: Composition and Sclccted Functional Properties oiTreated and Untreated .$orglnum Flour.

1. EtokAkpan, 0. U. anci Palmer, G. H. (1 980). A simple Aliamylase procedure for the estimation of&-amylase and diastatic activiq. j ouml cfthe Institute of Bxwing 96:89-9 1.

2. AOAC (1994). Official methods of Analysis. Assoc. of ,\na!yt.C3emists, Washington D.C

3. Draper A. (1994). Enzrsy density of weaning foods In "Infant Nutrition" Edited by Ann F. Walker and Brian A. Rolls. Chapman and Hall Pub L pp 2U9-233.

4. Akubor, P.I. (1998). Functional prupe:!ies of cowpca-plantain flour blends. Proceedings 22'" AnnuaZ NIFST ronference, 23"' --26Ih Nov. 1998. Abeokuta Volume I. Pp 63-65.

Suq~lc

PSF . SSF

; USF

USF - !in>.nroulcd a r ~ h u r n flour PSI: PFrtxelstinizcd rorghum flour SSF ; Sprout4 sorglwm I l m

l'unction --- propaits --.-- - -- --

PKOXIMA'IE C0MI'OC)ON (%) - Lcul &slation concentralion (W 4 00

4.00 '

2.00

pH

4.0? 5.03

5 5

Energy

( b u d 117.60 - -. - - 102.40

291.72

Moisurc

10.80 - 8.20 9.70

biscod~~ ?,ulL :CP) Ucndry

117.7 112.6

127.7

- Ash

-.-- 2.00 1.50

2.00

P ~ i ~ F a t

9.75 7.5D

10.06

)

- 02938 0.6177

0.5373

Carbc- hydrrlc

70.55 73.22

66.74

I'tbrc

2.50 1.50

2.00

4.40 5.40

9.50

.Hinerd content @pm)

P

0.471 - - - 0.2Y7

0.366

- C

0.043 0.040

0.042

K

1.569 1.537

-1.540

N

0.115 0.077

0.107

- ti rza Road, Abakalilti 1 1 1 1

an Editorial Sub-committee PROF. L C m OK011

,. 4 - '

Odo, M. 0. Chemical and microbiologic~~l properties of smoke-dried frozen fish sold in Abakaliki Ebonyi State

0. Akoma*, S. Musa, A. 0. Akoma and R. G. Asunmo Nutritional values of yogurt produced with locally developed starter culture isolated from 'Nono'.

J.V Akinlotan and M.K Alasela. Effect of varied temperature on the.weight and yolk index of stored eggs

Abolude, D.S., *Dalogun, J.K., 'Oladipo, M.O.A., "Ajibola, V.O., *Abdullahi, S.A., 'Ewa I.O.B., 'Umnr, I.M. 'Dalogun, G. I., 'Jonah, S.A., 'Ahmcd, A.Y., 'Adeyerno, D. J. and 'Onoja, R. 0. Analysis of elemental bioaccurnulation in the flesh of Oreochromis niloticus from Zaria using instrumental neutron activation analysis (INAA) technique

C.A.Negbenebor and M. Joseph. Storage stability of patties formulated from l x c f as

and washed minced fish during refrigerated storage.

Chapter 2: Cereals, Composite flours and baked products

1 Ajayi, 0.0, 20jo, MA*, 2~de-~n iowaye, B.1.0. and y yo dele, M.F.Proximate, mineral composition and functional properties of a local cultivar of wheat, alkama (Triticum vulgare)

S. U. ~waojigba', H. D. ~ e ~ b a ~ and L. ~ b o h ' Evaluation of baking and sensory properties of wheat-plantain composite biscuits

Adenuga W. and Adelaja S.O.Biscuit production using seedless breadfruit

Chinma, C.E. and ' Gernah, D.1 Physico-Chemical and Sensory Properties of Cookies Produced from Cassava I Soyabean I Mango. flour blends.

Alaka, I. C. and Okaka, J.C. Effect of Traditional Paddy Soaking'on Paddy Moisture Content and Milling Related Characteristics of Two Rice Varieties.

Fagbemi S, Ndife .J And Udobi .C.E. Effect of fluid soylecithin extract on the quality of bread

E.B. Banigo and I-1.D. Mepba. Certain functional properties of wheat - breadfruit composite flours

~riahu', C.C. and Ojo, M.O. Quality evaluation of maize and edible,mushroom based formulated food products

Mbaeyi, I. E. and Ani, J. C.Development and evaluation of breakfast flakes from sorghum and pigeon pea

Development and evaluation of breakfast flakes from sorg l~uni and pigcon pca

Mbaeyi, I. E. and Ani, J. C. Department Of Food Science And Technology

University Of Nigeria, Nsukka. ~miphie2003@yahoo.co.ulo

Introduction In many developing countries such as Nigeria, malnutrition is a common

dietat'y problem, which is said to be endemic. It is characterized by micro-nutrient deficiency and protein-energy malnutrition. Over the last few years, efforts have been mode to reduce or eliminate the problems worldwide, dietary diversification has been suggested by many workers as the ultimate solution to malnutrition. This diversification involves the use of commonly known and consumed grains and/or legumes in more than one form and still meet the dietary need of the target consumers. There exist a lot of other locally available cereals and legumes that serves as good alternatives to these more popular industrial raw materials in use. Consequently, there is need for some baseline study on the use of these underutilizes grainllegumes to identify and evaluate their characteristics and potentials to serve as good alternatives in product formulation. Among the myriad of locally available examples are sorghum and pigeon pea whose use are limited to the household level though they may have potentials for uses. Sorghum (a cereal) is a rich source of carbohydrate and amino acids but deficient in lysine and tryptophan. Pigeon pea (as a legume) is cheap and contains a relatively high content of protein (23%)'.

Material and methods One weight of sprouted (96hr) and pregelatinised (70°C) sorghum grains

were milled blended with graded proportions (1 00:O; O0:20; 70:30; 60:40; 5050) and used to formulate a flaked breakfast cereal. A commercial ready-to-serve breakfast cereal (X cornflakes) served as product control. ~hysico-chemical2 and sensory quality3 analyses were carried out using standard methods.

Results and discussion Sprouting and pregelatinization increased the protein content, ash, fibre and

carbotiydrale contents of the composite flours and products! The moisture content was reduced significantly (p<0.05). Similar results were obtained by increasing the concentration of the pigeon pea, leading to increased ash, fibre and protein content of blends. Table 1 shows the sensory scores of the composite flours used to formulate the product. The sweetened blends were preferred to the salted ones probably due to the preference of sugar - the sweetener. The sweetened products were used for the product development. The sensory scores of the product showed that the addition of pigeon pea flour had significant (p<O.O5) improvement on the quality of the formulated breakfast cereals when compared with the corresponding commercial products. Among the forrnulated products, those with pregelatinised cereal were more acceptable than those containing the sprouted cereals. Thus

1 ' ! -* I

sprouted and pregelstinization, when contrclled led to significant improvement in nutritive value, flavour, texture and colour of the food product. The use of pregelatinised cereal legume flour blends is riot very common in Nigeria. Promotion will be required to popularize the use of pregelatiniscd composites, which havc some nutritional bcnefits over the sprouted products.

Refrences , ' ~chendu, C.A., Oniamawo, I. A. and Adieze, S. (2004). Production and Evaluation of Doughnuts and Biscuits from maize-pigeon pea blends. Nig. Fd. J. 22: 147-1 53. 'AOAC (-I 995). Official mcthods of Analysis Association of Analytical Chemists, Washington, D.C 3~ei lgaard, M., Cille, G.V. and Carr, B.T. (1991). Sensory Evaluation Techniques, 2"" ed. CRC Press Inc. Ooca Raton, Florida, pp 22-45 1 Mbaeyi, l.E and Enwetuzo, J.C. (2002). Effect of sprouting and pregelatinization on the composition of sorghum (sorghum bicolor L.) 5 Nnam, N.M. (2001). Chemical, sensory and rheological properties of porridges from processed sorghum (sorghum bicolor L.), hambara groundnut (vigna subterranean L. veric) and sweet potato (Ipomoea batatas) flours. Plant Foods for Human Nutrition, 56:251-264.

Table 1: Sensory evaluation scores of the formulated products and a

A l l va lues are means of dupl icalo dotern i i~ ia l lon A = P S F t C C F (l00:O); B = U S F t C C F (00:ZO); C = U S F (100:O); D = P S F t C C F

(70:30); E = S S F t C C F (50:50); F=(100:0): G: C C F (IO0:O); H: S S F t C C F (GO ,lo); I:

'

U S F t C C F (60:10); J = U S F t C C F (50:50); k: S S F t C C F (70:30); L: P S F t C C F (60:10): hl: S S F t C C F (80:20); N = P S F t C C F (50:50); 0= P S F t C C F (80:20); P= U S F t C C F (7030); Q=USF, R = P S F

S=SSF, T=conlrol , LSD= Least Significant Dif lerence

A18 EFFECT OF SOME ORGANIC WASTES ON THE BIOGAS YIELD FROM CARBONATED SOFT DRINK SLUDGE.

Uzodinma, E.01; Ofoefule, A.Uf; Mbaeyi, P ; Eze, J.11 and Onwuka, N.D2 fNatio/~al Cer,fle for e w g y research ar~d Deve/o/~rnetlf,

?Deparfu~wt of Food Sc ie tm and Technolorjy, University of Nigeria filsukka, Erlugu State, Nigeria. i~ni~.,~~zodinrn;?@yaI~oo,coni

INTRODUCTION The rnajor ingredients of carbonated soft dr-irik beverages in addition to water arid carbon

dioxide are sugar (9.5-13.40 Brix), fla~orings, colors and acids (pH= 2.6 to 4.0) which vary frorri different rnanufacturers[l]. Consequen!ly, sludge wastes thrown out from production of thesc beverages are fertile grounds for the pathogenic riiicro-organisms of yeast and bacteria [2]. The gencl-ation of biogas, a nori- exhausttiic c n q y iiirough ariacilobic digestion has been carried oirt '

though with low yield 131. This study in\icstiyatcs i~!r!hcr the c k c t of otiicr biogenic wastes: palm oil slutlge (POS), soybean cake waste (SW), powdered ricc !ii.rsl:(IW) and swine dung (SD): on biogas yield of carbonated soft clrink slc!clge (CS).

MATERIALS AND METHODS The CS w s ! e collected fronl the soit tirink cornpar.ty at Ninth mile corner , Eniigu state,

Nigeria! was charged into a biodigesteroi 13GL capacity \;iili!e its blends (CS:POS, CS:SW, CS:RH arid CS:SD) were separately chargcd into clifforefit ttigcsters of ;,;/orkiry \/oii~mes 136 arid 117L. Anaerobic digestion was !hen allowed !o take place in each of the digesters at the prevailing ambient temperature and pressiire conclitions for 25 days, Chen-tical and flarlimable gas composition analysis was car-ricd out using s!andard rriethods of (41. The data obtained for the volume of biogas yield were subjectecl !o statistical ariaiysis u s i r ~ ~ SPSS version I 1 corriputer package.

RESULTS AND DISCUSSION 'This experimental st i~dy was carried oil! viilhin daily anlbierit ternperztuse range of 26 to

36% while the infli~ent tenlperaturc of digestcr ra!iged bct\,veerl 28 to 400C. Biogas procluction from CS, CS: POS and CS: RH digester systerus comtiwi~ced after 24h, 72h and 4811 post charging periods, respectively (fig.1). The CS: SW and CS: SD systems started biogas productioii within 24h post charging period. Also, production of firtmrnabie gas from each of the cligestcr systems (CS, CS: POS, CS: SW, CS: RH and CS: SD) took place at different tiriie lags: 8, 15: 9! 10 and 6 days, respectively. Pure CS feedstock system stopped flatnrnzble gas procluction after one and half

weeks when the pH of the system reverted to 5.20. Biogas systems ale I I I Y ~ ~ , ~ r l , uuy-...

ttie rnettianogens that corivert lhe digestible matter into flammable biogas survive optimally within w

pH range of 6.6 to7.6 ancf up to 8.2. Findings of [5] indicated that biogas production was significantly affected when 111-1 of the digester slurry decreased to 5.0 due to reduction in methanogenic activity of the digester system. Blending of CS and SW, RH or SD resulted to enhanced flammable gas production while that of CS arid POS wastes yielded poorly (fig.1). The poor perforr~iance of this blerid would have resulted from the low pl-l of the combined waste (4.4) at charging. The other blends (CS: SW, CS: RH and CS: SD) h a d pH of 6.63, 6.30 and 6.11, respectively, at charging prior to digestion. Mean biogas yield of CS was 7.1L while those of CS:SW,CS:SD,CS:RH and CS:POS wcrel 1.6,9.7,7.7 and 3,5L,respectively(95% confidence level). The overa!l results indicate that the pH of the CS waste was stabilized through blending and ilammablc biogas was continuously gcneratcd oven though not all the blends produced maximally.

REFERENCES Potter, N.N and Hotchkiss, J.H (1996). Beverages. Journal o i Food Science, 51'' ed., Chapmarl a n d Hall Inc; Ncw York, pp 437 - 442 Frazier, W.C and WesthoTf, D,C (1995). Botllecl Beverages. In Iood microbiology. Tata IvlcGraw Hill. New York or India, pp 31 2 -- 313. Ezc, J.1, Onwuka, N.D and Olteke, C.E(2003) Generation of biogas from brewery effluents. Nigeria Jourr~al of Solar Energy, 14: pp 115 - 120 A.0.A.C (1 990). Official methods of analysis: Association of Analytical Chernists. 14th Edn, Washington, USA, 22209 Sahota, P a n d A! Singh, (1996). Res.Dev.Rep, 13: pp35-40.

E10 PRODUCTION AND EVALUATION OF JAM USING STAR FRUIT [A vcrrhoa c a r m bola (L)]

INTRODUCTION Star fruit is a yel!c!v-green iiavoirr-fir1 h i t thal is like a sla' ai;co~.(lirq to Soyad [ I ] and it appears Ynxy, firrn vrilll ;1 ~rniciuc s h ~ p c . TIE frui! flavour rnngcs f r m vory sour to mildly sweetish and tastes like n mixtl..rre of kiwi, apple ;!nd piiwapplc. The fi-irit is n gcmd scurce of vitamin (it is pr-iniarily sold as a fresh fruit , picltlecl in sauces or incor'poraied in a wide variety nf fishes, salads, d~?sserts m d drinks). It coirlrl also be cut cross-sectionally and dried as reported by Carnpbell atid Campbell (21. 'Yilh all 11:ese pottittials, this fruit could be d~vcl-sified into jcllies, jam, mnrrrraladc and prescrws to bi'iry thrt latwtt pn t r? iMs to limelight this all s[:asonnl fruit. Jan1 im:, be from a singlc cr n conit~il~ation of t\m or 11\oi[? frui!.; driccl, ca~ i r~cd fruits or pi-cscr-vcd p~ili? may'also be LISN~ Gale [3]. Also, the use of o~ost other i~u i ls like apricot, str;wiSerry peach: ;-)li~ni, cherry, $nea@e: wangoes, tomatoes, paii11, app!tis, p e m ;inic!ig nitw fruits ?lad heen over-flogged ; i i

jam production in it;c tci~~peratn m r l fropical rcgiciis. f,&c?rl:.vl;ile. s!x fi-nit as an I I E ~ ~ P T - ~ ; ; < / : l ~ ~ l ~ f j f r ~ j i l L C I J ; ~ ~ ljc >rc:crypd :j; j::t.i?,

sweetener lo Itorley allhough they arc all highly rated. There were closely related values for protein m (1 53-2.18%), fat (trace), fibre (5.0%), ash (0.5-1 .OX), moisturc (64.0-65.5%) and carbohydrate (25.82-27.97%). The pH ranged bctlxcn 2.832-3.628 when coriipxcd miih the control (3.332). Tho pH was \!~itt~in the acidic rariyc! probably tiire to thc highly acidic fruit extract. This explains iis astringent arid stiar-11 taste which suggest that !tie gulp woulrl twe t ~ e e r ~ rich in pectin needed for jam production since substances with high pectin value were always associated with high acidity as rcpo~ted in jalm frorri Spondias maubin' fruit pulp according Oyewole and Adepoju [5]. Meanwhile, tt-ic pcclin was not so Irigh in slar hi i t pulp. The titrable acidity was bct\:;iccn 0.800-1,933°/~ in the jam from unripe fruit, [.).857-1.Giji")a i r ~ rip? fr~rit jam w i m con~pai-cd with the control (1.267%). Tlic ripe and fsirly ripe star fruit jar11 pro(!ucts t1ac.l sinilar total sugar (1.3589 arid 1.34133 (ll~rix, respectively) tvlton (;oi~ipxctl ~'i ' i tt~ the co~.itt.ol (1.3557 :'ljl-ix) unlike thc unripe star fruit jam , , (1.J493). Tile ripe star f r u i t im i:l2s :i gosd sourctt of rnrlqnesiuni, calcium, phosphori~s and iron. Sicrtiix rcsulls ~;oii~;~i?rct! io ti^ corrl~mcii-il jain v:crc rciportcd by Oyc::?ole and Atiepoju (51 staiing Ilmt Spouclins r m n b h fl-uii pulp was a good source of thcse nincrals and ~vater-soluble vitamins. Conclusi\~cly, thc s!ar fruit c m bc! t.isctl in j m prorluctio~l rrnd honey ct)uld be i~sed rts a si~bstituie for sugar for some consuri1el-s ~ i l 1 0 art? ~!ia!)etic or do not ~ppreciate sugar.

EFFECTS OF FERMENTATION CIN THE PHYSIO-CHEMICAL. SENSORY "" QUALITIES AND STORAGE S'C'ABILITY OF LOCALLY PRODUCED '

k OGHURT IN ENUGU METROPOLIS

Wbaeyi, I.E. and 4wziem, N.E. Depaltlnclrt of Fo ~d Science and T!,!clv~ology, Univefsity of Nigeria .

kiphie2003(?,;,v1li00, CO, uk . , , .

I '.

NTRODUCTION ~cnnentation is a proccss thal transforms the sl t)slraIe into a product that rnay have enhanced ,

rrutr~!io~~iil antllor' co;!lmolcptic cha xteristics accoi~litq to Edward [ I ] . Fermented proclucts include snwkraut, pickles, I)i:t:r, wine, l ry sausago, ga 5, ogi dairy prutlucts (koflr, yq~hurt) among ,. . , others, Fcr111etitr:d dairy produCts had formed a p l r l ot people's diet around the world and .as a result of. the presence of the lactic acid bacteria, be~,au:;o they are able to impart health benefits to , % , .

'

the consurner Farriworth (21 It is ;liyt~ly misl~adir-i! i l ;~ promote yoghurt as having these health- ,;:,, ', promoting properties unlessDit con.ains a niinir~~unl evel of viable probiotic bacteria ~10hcfuIrnl of , . lactic acid bacteria) still prcserll 31 the expiry da : 2 . 'This is not often the case in commercial ,;+

products due tu Iqw Ir:vitl of probi )tic bacterii atlriL~u:ed to slow growth, lack of corppetitiveness i3. with the strairls of the starter culture and incomplek fernlentation which occurs beforg the yoghurt 1 .: , sets. These in turn affect the nutrit onal compositi~n, organoleptic attributeslproperties and in turn, ;tj the shelf stability of the cornmercia product. Thus, i ;e research aimed at deterrqining the effect of , , ; . . fermentation on the physico-chemical properties, sensory qualities and storage st:qbility of the commercial yoghurt vended by loc:l food hawkers. \

i , , .

MATERIALS AND METHODS Three brands of locally produc(id yoghurt (A-C) xere purchased from Ogbcle mqin market in .;.

Enugu niotropolis. Pl\ysical parameters !pH, total solhle solids, titrable acidity, lotal sugar (~Brix) . . and viscosity] were (leternlined in i~ccordance to A C K [3]. Proxima!.. c~mposition was done by AOAC [3]. Microbial arlr-llys~s according to I-larrlgar) at icl McCance [4] was done on deblan Rogosa, ,,

Sharpe (MRS.) agar io isolate and characterize tnc: starter cull~!!.c. Pure isolates of lactic acid bacteria were stored in bijou bottles and used lo fcrrrljnt fresh milk sanlplcs which wer? compared : with the commercial pi~~ductslbrand:;. The enumeratic,n of the microbe (lotal viable couil.t, mold and colifol-m counts) was toy Harriga anci Mccarlca [ L t ] Th~t products were stored for 28 days to gssoss tilo vi;lbility of tho :;I:II~cI cl~l~ll;n . a ~ l S;IIU~I~:S w(:iu ,~a~ilor; i lud wwkly. Sor~sory t~valuallori 'was dolie usitlg Y.poi,)l tl~:(Io~iic scale a i d 30-trained pa~~ i i i s t who were familiar with the products to indicate their respo~~sc:;lacceptabilil/. All data were :;tatistically analysed using SPSS Versipri , . 11 Package, , . . . .

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. .

2'28

RESULTS AND DISCUSSION Table 1: Proximate composition of three commercial yoghurt brands . . . . . . . . . . . . . - . . - . . . . - . . . . . . .- . . - . .. ......_. -_..

;Chemical omp position % ;Functional Parameter - . . ...... - ., -

~ a m p l o ~ ~ a i s l u r e Crude Crudc Crudo :~arbohy- l ~ i b r o 'Told ~ o t a l Titrablo P ~ c o a l t y

I prolain ' fa1 ash ldralo I :fi.,"suyar solublo acldlty (%) ((Cp) 1 . 1 (Obrix) ,solid (96) ;

, , I A jht3.1 2 5 OR + U.OH ?:2,60 $:3,24 ~ r s c e i 3 7 5 2 : 5 , 6 1 ti1.20

10.727 0.Q07 '0.015 10.577 i . . iss,o- . . . . . i . . . . . . . . . . . . . . . . . . . . . . . ;0:093 10.33 lo.115

B - + 2 911 1 ' 0 49 ~ ' 3 . 2 4 24.33 lTrace/3.69 214.67 ti0.83 10.259 0 rJ(;,5 0.067 0.145 j 10,014 j0.33 ,0.033 - . . -.- . - ... -- . . . .

C 185.0 2 3.43 1 ' 0 . 5 3 + i2.383 + 8.66 l~race!3.78 +!3.33 -- i i 1 .53 2184.66 - i0.289 (1.043 0.333 -'0.441 - - - 1 10.046 .OX 11.333 ;0.507 % ' j . . . . . . . . . . . . . . . . , . . . . I^ . I . -- .-. : . . . -. . . __.-.-_ -__,_ _-.._- _ .-.---_-

, I ,

Valties arc rncalis oi t~'iplicilk dctcrn~inalio~islrcatlings 2 SE Table 1 rcprc:scnls tllc proximate coniposilion of the commercial yoghurt brands, The moisture

content ran!gecl b c h m n 85.11 ?:i.O%. The protein content (2.76-3.12%) was similar to results oblainecl by M d ~ i ~ r n r m l et a/ [5j. The fat conlents varied between 2.38 and 3,24%, There was no' significant difteronce (P < 0.05) in the fat contents of the three brands probably due to the fact that ,

fat is the c:mponerlt that varies least due lo fermentation. The ash (0.49-0.98%) could be probably dl~e lo high lolal solids of the yoghurt. pH wers not sirnilar lo thc~ obtained by other researcliers (1, 5) cluit to ir~cornpletc titinicn!aliorl. The total solids quite lower that those obtaincd by ,

Mtrl~aiwl~cxj ct i.11 (!)I who opirwtl l1~1 hiylwr lol;rl solids luvd s u o l ~ ~ r ~ d lo irlhibil growlh of I ~ l i c x i d bacleria in non-dairy yoghurl. '1'1.~2 total niicroblal load differed significantly (P < 3.05) probably due to the fact that nicrohal growth is an aulocalalyl~c process and inoculation'wilh a starter culture at optimum growth cor~htioris for mesophiles (L/\B) could probably be responsibk for the high total microbial load at evcri the inilial days of stcrage (51. Also, low litrable acidity from incomplete , , , '

fcr~nenlation negatively affcclod Ihe total solicls, protein and fat. Thus, in turn mated sweetness jsouriness) allt~otrqh I l w e was a significant difference a1 P < 0.05 in colour, consislency and Ic!xll.trc!, At t k s o w w : prtii);trly tluc to hcon~plato fe~-rnentalio~l in the locally prod,uced yoghurt. . - , lI~o~t:forc, coi~pIc:ti! I t r r rne~Mon rnirst be eric:oi~~ayed Lo attiill Ihe desirable nutritional, organoleptic avd sale ~ roduc l lor the consu1ilal.s.

REFE~ENCES ,

1. Edward. R.F. 12003). Handbook oi Fernlenled Funclitr,ml Foods, CRC Press, New York, pp. 1-49. ,

2. Farnworth, E.R. (200:!). Thc Beiwfiaal I lcallh Ellccb; of Fcrrnenled topds - Polenlial Probicltics n:ound the World. J. Nulraceu. Fi~ncl. b: Mctl Foocis 12.94-103.

3, AOAC (1990) Officinl I\/lcrliods c ~ f Analysis; Association of Official Analytical Chemisls, 151l1 ed., Arlington, V.A., US./ .I, tlarrigarj, W F, m? McCmcc:, FcE (1931). Laboratory Methods in Foods and Dairy Microbiology, Academic Press

lric Ltd, 1.0ndr111 5, I~4i1ho1~imet1, L H . , l Y ~ ~ I , i i k l l t , Ivl..d : &x#h, T.A. nr. 11 1-Iyavroyc, E.O. (2005). Effccls of Culluro Concenlralion and

Irmculnlion rc~iqx:r;ilure on tJ1 ys ....~-cl~~ili~r-lI, P~lic;ol~1:~1 aild Orgal~olcplic Propc~lies o l 'foghurt, Nig. Food I 23.156-1 (j5