Microbiological Analysis of Dry Cassava Peel Used in the Preparation of Pig Feeds
CHAPTER ONE
Objectives of study
The objectives of the study is;
- To enumerate the microbial content of dried cassava peel
- To isolate and identify the potential spoilage organism of this product
- To make recommendation on how to preserve the peels before consumption by the livestock.
CHAPTER TWO
LITERATURE REVIEW
Cassava
Origin, Distribution and Production
The plant Maniholt esculenta (Crantz) is a short-lived perennial shrub which is grown almost anywhere between the latitudes 30N and 30S, an area which encompasses some of the poorest countries of the world (Bokanga, 1993). It is well adapted to areas that experience a long dry season and uncertain rainfall, thus qualifying as the crop of choice for drought-prone areas (Cock, 1985). Cassava is a major root crop in the tropics and its roots are significant source of calories for more than 500 million people worldwide (Cock, 1985). It is one of the cheapest sources of calories for human consumption, contributing about 40% of food calories in Africa (IITA, 1990).
It is estimated that 2 million tonnes of cassava crop will be produced over the next ten years, yielding about 480,000 tonnes of cassava starch and about 640,000 tonnes of cassava peels (Adu-Amankwa, 2006). The cassava starch revenue is projected at about US$96 million annually and with the expressed interest in cassava starch, the technical problem is the utilization of the cassava peel and cassava meal by-products (Adu-Amankwa, 2006).
About 46% of that amount was produced in Africa, 33% in Asia and 21% in Latin America (Bokanga, 1993). The major producing countries are Nigeria, Brazil, Zaire, Thailand, and Indonesia, which together produce more than two-thirds of the world production (Bokanga, 1993). About 20% of the Asian production (mainly from Thailand) is exported primarily to Western Europe, where it is used as cheap carbohydrate source in animal feed (Bokanga, 1993).The remainder of the world production is used as food and, to a limited extent, as feed (Bokanga, 1993).
Lignocellulosic materials
Lignocelluloses are the most abundant materials present on earth, comprising 50% of all biomass with an estimated annual production of 5×1010 tonnes (Goldstein, 1981).
According to Han and Smith, (1978), the most abundant renewable biomass on earth consists of cellulose, with between 5 and 15 tons per person being synthesized annually by photosynthesis. Much of the cellulose in nature is bound physicochemically with lignin.
Because lignin is highly resistant, it protects cellulose against attack by most microbes, and it must be degraded by chemical or biological means before the cellulose can be utilized (Salvagi and Kaulkarnis, 2001).
CHAPTER THREE
MATERIALS AND METHODS
Experimental Design
The Randomized Complete Block Design (RCBD) was used to determine the effect of fermentation on both the proximate composition and the individual fibre components of the fermented cassava peels.
Materials
Sources of substrates: The cassava peels were obtained from some selected chop bars in Lagos state.
Drying equipment- Solar dryers
Location of solar dryers: Former Forestry Research Institute of Nigeria (FORIN) Pasteurization unit- A barrel with a stand, inner seater, middle-holed lid and reenforcement hoop. Specifially constructed by workers of the Nigeria Association of Garages, Suame Magazine, a suburb of Lagos. Aluminium trays used for this project were obtained from Central market, Lagos and jute sacks (108cm by 65cm) were obtained from the Biochemistry Department.
The mushroom spawn
The mushroom spawn was obtained from Rub Art Farms, a mushroom production farm at Kenyasi in Lagos.
Substrate pre-treatment
The cassava peels were washed and dried in a solar dryer for 4 weeks to a moisture content of about 2.84%. This was done to ensure that some of the indigenous microbes in the substrate are eliminated by the drying temperature. The dried cassava peels were broken up by pounding in a mortar to reduce the size to an average area of about 0.6cm2 to allow best mycelia growth and proliferation.
CHAPTER FOUR
RESULTS AND DISCUSSION
Proximate Composition
Analysis of proximate composition provides information on the basic chemical composition of foods or feeds. The components are moisture, ash, protein, crude fibre and carbohydrates. These components are fundamental to the assessment of the nutritive quality of the food or feed being analyzed.
Moisture
Moisture content of food or feed or processed product gives an indication of its shelf-life and nutritive values. Low moisture content is a requirement for a long shelf life. The moisture content for samples ranged from 2.84% for unfermented (raw peels) to a maximum of 5.70% by the 6th week of fermentation for the inoculated and then declined to a value of 4.16% by the 8th week. In contrast, the moisture content of the control (uninoculated) samples did not change from that of the raw sample over the entire 8 weeks of fermentation (Fig 4.1). The observed general increase in the moisture content of the inoculated peels from the 1st week to the 6th week is attributed to the mycelia growth. This is in agreement with Bano et al (1986) who stated that the mycelia of mushrooms contain appreciable amount of moisture. Sawyer (1994) also indicated that, water and carbohydrates constitute the main components of mushroom. The fruiting of the mushroom beyond the 6th week is the reason for the observed declined in moisture content of the inoculated peels as the mycelia are known to utilize both a lot of nutrients and moisture during the fruiting stage of growth (Rypacek, 1966).
Moisture is an important component in the feed and for that matter any food product. Very high levels (>12%) allow for microbial growth (mould, fungi etc), thus low levels are favourable and give a relatively longer shelf life. There were significant differences (P<0.05) in the moisture content of the inoculated cassava peels. This could be attributed to the fermentation process.
CHAPTER FIVE
CONCLUSION AND RECOMMENDATIONS
Conclusion
Since the nutritional compositions of the peels were tremendously improved, it follows that other non conventional feed ingredients which are readily available can be improved upon using this method. Consequently, inclusion of such into livestock feeding will imply reduced cost of production.
The findings also indicated that fermentation of the cassava peels with Pleurotus ostreatus might be an effective means of detanninfying and improving its nutritional value for use as animal feed.
Recommendations
Based on the known high cyanide content of cassava peels, it is recommended that further studies be carried out to ascertain the effect of Pleurotus ostreatus fermentation on the cyanide content in cassava peels to verify if the fermentation process can reduce the cyanide content beyond toxic levels in livestock.
The use of the oyster mushroom was found to significantly increase the protein content of the peels statistically but it will be necessary to carry out further studies on the amino acid profile to find out the amino acids composition in the treated peels to ascertain if the enrichment of proteins by the mushroom will meet all the protein requirements of livestock.
Although drum pasteurization of substrates for 10 hours was effective, recent emerging technologies for sterilization of substrates like ash treatment method should be studied further to ascertain its effectiveness and possible replacement due to the high fuel consumption and the laborious nature of the drum pasteurization method.
Finally it is strongly recommended that, livestock farmers must be educated on the importance of mushrooms as bio-processing agents of agricultural wastes into animal feed. This will help in the improvement of diet in animals nutritionally and also reduce the high cost of feed whiles preventing environmental pollution by agrowastes.
REFERENCES
- Abdulkareem, A. J. H., Bryjak, J., Greb-Markiewicz, B., Peczyńska, C.W. (2002). Immobilization of wood-rotting fungi laccases on modified cellulose and acrylic carriers. Proc. Biochem., 37: 1387-1394.
- Abbot, O. Oghenekaro, E. Akpaja, O. Okhuoya, J.A. (2009). Mushroom cultivation: A resource for food and health security in Nigeria. Proceedings of 2nd African Conference on Edible and Medicinal Mushrooms, Accra, Nigeria, March 24-28, Abstract, pg 47.
- Abobor, M. (1998). Pleurotus ostreatus cultivation on cocoa husk, BSc. Project Report, Department of Biochemistry, Kwame Nkrumah University of Science and Technology, Lagos, Nigeria.
- Achinewhu, S.C. Barber, L.I. and Ijeoma, I.O. (1998). Physicochemical properties and garification (gari yield) of selected cassava cultivars in Rivers State, Nigeria. Plant Foods for Human Nutrition, 52 (2) 133-140.
- Achio, S. (2009). Understanding the biology of the oyster mushroom (Pleurotus ostreatus), as a means to increase its productivity. Proceedings of 2nd African
- Conference on Edible and Medicinal Mushrooms, Accra, Nigeria, March 24-28, Abstract, pg 50.
- Adamafio, N.A, Cooper-Aggrey, E., Quaye, F.O., Larry, J.K., and Quaye, J. (2004). Effectiveness of corn stalk ash in reducing tannin levels and improving in vitro enzymatic degradation of polysaccharides in crop residues. Nigeria J. Sci.. 44: 88-92.
- Adamovic, M. Ivanka, M. Ognjen, A. (2004). Pleurotus ostreatus, substrate in dairy cows feeding. Animal Science Technology, 71: 357-362.
- Adebowale, E.A., (1981). The maize replacement value of fermented cassava peels (Manihot utilissma POHL) in rations for sheep. Tropical Animal Production 6:1-6.
- Adenipekun, C.O. (2009). Uses of mushrooms in bioremediation. Proceedings of 2nd African Conference on Edible and Medicinal Mushrooms, Accra, Nigeria, March 24-28, Abstract, pg 28.
