ONION IS ASSOCIATED WITH MICRO-ORGANISMS WHICH ARE CAPABLE OF CAUSING SPOILAGE.
Onion is associated with micro-organisms which are capable of causing spoilage. Onions with rots were examined microscopically. A solution of it was made and the serial dilution of 1:10-1 to 1:1-5 were made from 10ml of the onions sample. From the dilution, 1ml of each diluent was plated on nutrient and saboor and dextrose agree to permit the grouth of the common bacterial and fungi, from the roffen onions. Duplicate plates were performed for each dilution. The plates was sivirled of gently to ensure even distribution of diluent and was incubated in inverted position of 370 c for 24 hours. After 24 hours, the colorues were counted, with vales yielding 30 to300 (to avoid TFTR and TNTC), the viable count per ml was defermined by multiplying the average number of colories of the duplicate plates by the corresponding factor (MPN table). Gram staining was carried out on the colories and examined microscopically. Representative colories were seperately sus-cultored on nutrient agar slopes for confirmatory characterization of the organism present Biochemical test for identification was also carried out. The result showed a mixed flora of bacterial and fungi including moulds as the organism responsible for spoilage of onions. The fungi isolated were Mucor spp rhizopus spp, Aspergilus spp and saccharomycis spp. The bacteria isolated from the sample were staphylococcus aureus, streptococcus pyogenes and Bacillus spp.
Table 2: total plate counts ---------------25
Table of content
1.0 Introduction 1.1 Background information
1.2 Aims of this research project
1.3 Statement of problems
1.5 Significance of study
1.6 Limitation of this project
2.0 literature review
2.2 Species of onions
2.3 Composition of raw onions
2.4 Dehydration of onions and uses of dehydrated onions
2.5 Basic principles involve in preventing microbial spoilage of onions
2.6 Spoilage of micro organisms
3.0 Materials and method
3.1 sample collection
3.2 materials used for the preparation of the medium
3.3 preparation of media
3.4 Preparation of sample
3.5 Microbial counts staining and microbiological work
3.5.1 Biochemical test for identification
3.5.2 Motility test
3.5.3 Sugar fermentation test
4.0 Result discussion
5.0 conclusion and recommendation
1.1 BACKGROUND INFORMATION
Onions is a vegetable crop and ancient in nature if is through to have been domesticated in the central Asia. It is one of the oldest vegetable cultivated by man for food. In the world onion buld are found in ancient Egypt, India, China and Europe during the middle ages, and in the late sixteenth or early seventeenths centuries, it spread to the new world by the Spaniards. The crop is now wide spread in both temperate and tropical regions with Europe as the largest producers (cobley and Steele, 1976).
In the tropic most onions are grown with irrigation during the relatively cool dry season in semi arid region, they are not good crop for hot wet tropic. Onions can be grown under a wide range of climatic condition but they succeed best in a mild climate without excessive rainfall or great extremes of heat and cold. They are not suitable to regions with heavy rainfall in the lowland humid tropics. Cool conditions with an adequate moisture supply are most suitable for early growth followed by warm drier condition for maturation, harvesting and curing. They can be grown on a variety of soils, but the soil should be retentive of water, non – packing and rich in nutrient, a good fertile loam usually gives the best result. They may be grown successfully on peat soils. The soil optimum pH is about 6.0 – 7.0 (alkaline) (carl and Hall, 1986).
In storage a specific environment must be provided for the onions, if a high quality product is to result. Storage losses are a function of storage environment as well as the condition and cultural practices used during the growing season. Proper control of storage environment can however, significantly extend the storage season from that which would result from