ABSTRACT

Stored locust bean samples were purchased from Uselu market and analysed for their fungal load and physicochemical properties such as moisture content, pH value and titratable acidity. Enumeration of the total fungal species was carried out by pour plate technique using appropriate medium, potato dextrose agar (PDA) with antimicrobial agents (streptomycin), incorporated to inhibit bacteria growth. The fungal isolates were identified using cultural and morphological characterization. Moisture content determination was done by drying to constant weight in oven at 103°C, the pH value was determined using a pH meter while titratable acidity was by acid-base reaction using 0.1N sodium hydroxide (NaOH) solution. The total fungi count on potato dextrose agar was 2.0x10-8 from Uselu market. The moisture content was 18.9%, the pH value 6.1 and titratable acidity 0.61ml of 0.1N, NaOH. The species of fungi isolated and identified at the end of the analysis were Fusarium sp, Aspergillus flavus, Penicillium sp, Saccharomyces sp and Aspergillus niger. The identification was based of morpohological characteristics. These fungal colonization and contamination of stored locust bean cause inedibility, reduce market value and depletion of its nutrients. Hence, adequate drying of crops, prevention of moisture re-absorption and the general improvement of storage facilities at all levels of production is recommended as a safe guard against fungi deterioration of locust bean.

CHAPTER 1

2.0              INTRODUCTION

The seed of locust beans (Parkiabiglobosa) plant found growing in the Savannah Africa provides one of the popular seasonings in African diet. The nutritious and delicious food spice is popularly called “ogiri” in Igbo, “iru” in Yoruba and “dawadawa” in Hausa in Nigeria. It is heavily consumed in Nigeria, Ghana, Sierre Leone and Togo (Odunfa, 1985). It serves as source of protein for most of the people whose protein intake is low due to high cost of animal protein sources.

The African locust bean tree, Parkiabiglobosaare perennial trees legumes which belongs to the sub-family mimosoideae and family leguminosae (now family fabaceae). They grow in the Savannah region of West Africa up to the southern edge of the Sahel zone 13°N (Campbell-Platte, 1980). The plant occurs in a wide range of Natural Savannah woodlands and ithas the capacity to withstand drought conditions because of its deep tap root system (Nwadiaroet al., 2015). A matured locust bean tree (20-30years) can bear about a ton and above harvested fruits. From experience, the tree can start to bear fruits from 5-7 years after planting (Musa, 1991). The African locust bean tree grows to about 20m in height and has bark evergreen pinnate leaves. Its fruit is a brown leathery pod of about 10-30cm long and contains gummy pulps of an agreeable sweet taste, in which lie a number of seeds. It is important indigenous multipurpose fruit tree.Parkiabiglobosa tree plays vital ecological roles in recycling of nutrients from deep soil, by holding soil particles to prevent soil erosion with the aid of its roots. It also provides shade where it is found (Campbell-Platte, 1980). This tree is protected by peasant farmers and rural dwellers for its many benefits. Its wood is a source of fuel energy. It helps to enrich the soils nutrient.

The most important use of African locust bean is found in its seed which is a legume, although it has other food and non-food uses especially the seeds which serve as a source of useful ingredients for consumption (Campbell-Platte, 1980). It has been reported that the locust bean is rich protein, carbohydrate, soluble sugars and ascorbic acid. The cotyledon is very nutritious, has less fibre and ash content. The oil content is suitable for consumption since it contains very low acid and iodine contents. The oil has very high saponification and hence would be useful in the soap industry (Alabiet al., 2005). It has also been reported that the husks and pods are good for livestock (Douglass, 1996; Obiazoba, 1998). The locust bean tree is also important in medicinal practices in treatment of aliments such as bronchitis, pneumonia, malaria, diarrhoea and as poison for sore eyes (Farombi, 2003).

Although microorganisms of all groups including bacteria, protozoa, algae, viruses, fungi together with insects and rodents play significant role in food deterioration, the most active and more versatile organisms that affect locust bean seeds and its products causing spoilage when stored are species of bacteria and fungi (Omafuvbeet al., 2000). They can occur on growing crops as well as harvested commodities leading to damage ranging from rancidity, odour and flavour changes and germ layer destruction (Cutler, 1991). In a study to identify the bacterial and fungal flora of deteriorated and maggot infested samples of fermented locust bean seeds, the isolated fungal species were identified as Aspergillusniger, Aspergillusflavus, Penicillium, Rhizopus and Candidaspecies. Parkiabiglobosa seeds are subject to degradation induced by diverse organisms including fungi which are among the most active microorganisms in these processes (Popoola and Akueshi, 1985). Microorganisms associated with fermented locust bean seeds have been widely studied (Odunfa, 1981; Ikenebomehet al., 1986; Odunfa and Oyewole, 1986; Ogbadu and Okagbue, 1988). Bacilli and Staphylococci were observed to dominate the fermentation together with a number of fungal species causing deterioration of this especially in storage in Northern Nigeria.

1.1       AIM

·         This study is aimed at DETECTING THE FUNGI SPECIES INVOLVED INPARKIABIGLOBOSASPOILAGE.

1.2       SPECIFIC OBJECTIVES

·         To isolate and identify fungi associated with locust beans (Parkiabiglobosa).

·         To determine the pH, moisture content and titratable acidity of locust beans.