AN ASSESSMENT OF THE MYCOFLORA OF STORED LOCUST BEANS (PARKIA BIGLOBOSA) PURCHASED FROM USELU MARKET

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 2.0×10-8 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 ONE

1. INTRODUCTION

Daddawa also known as iru, among the Yorubas in South-west Nigeria, is a popular condiment used as taste and flavour enhancer in soup and dishes in Africa. Daddawa is traditionally produced from locust beans (Parkia biglobosa) seeds (Farinde et al., 2017).Odunfa (1981) stated that fermented locust bean seed is commonly consumed in Ghana, Nigeria, SierraLeone and Togo. In Nigeria it is called iru in Yoruba, dawadawa in Hausa and ogiri `igala in Igbo. It is also referred to as kinda in SierraLeone and kpalugu in Ghana. Preservation and preservatives are designed to inhibit/control the activities of spoilage causing organisms in food, a process also referred to as sanitization. Spoilage causing organisms due to their growth and metabolic activities produce by-products, which change the texture, taste, flavor and the aroma of the food. Preservatives by their nature are intended to keep the food devoid of these changes. Preservatives act on both Gram positive and Gram negative food spoilers (Jay, 2000). The general idea of products having preservatives is to increase shelf life and prevent items from spoiling. The more shelf life a product has, the more marketable it becomes. The use of preservatives makes products stay fresher, longer and give more time for products to be used (Bumpres, 2010). Preservation and preservatives are designed to inhibit/control the activities of spoilage causing organisms in food, a process also referred to as sanitization. Spoilage causing organisms due to their growth and metabolic activities produce by-products, which change the texture, taste, flavor and the aroma of the food. Preservatives by their nature are intended to keep the food devoid of these changes. Preservatives act on both Gram positive and Gram negative food spoilers (Jay, 2000). The general idea of products having preservatives is to increase shelf life and prevent items from spoiling. Abstract Daddawa also known as iru, among the Yorubas in South-west Nigeria, is a popular condiment used as taste and flavour enhancer in soup and dishes in Africa. Daddawa is traditionally produced from locust beans (Parkia biglobosa) seeds. This work was carried out on the preservation of fermented Parkia biglabosa seeds sourced from local producers and laboratory produced. The local and fermented laboratory controlled samples were treated with of Ginger extract 8mg/g and 2.5mg/g of Ascorbic acid. A control experiment was left untreated. The samples were stored at ambient temperature (34ºC and 30ºC) for 30 and 120 days. The analysis consisted of aerobic and anaerobic mesophilic count, Staphylococcus count and Fungal count, detection of Escherichia coli, S.aureus, Salmonella sp, Mucor sp and Rhizopus sp. Contaminant isolates were identified from locally produced, laboratory treated and untreated (Control) using standard procedure.The proximate analysis and organoleptic assessment of the purchased, laboratory treated and untreated (control) locust bean cake were carried out using standard procedure. The treated locust bean cake indicated microbial log reduction at120 days due to the effects of the preservatives; the Control shows microbial Log increase in the untreated locust bean cake.Isolated and characterized bacterial isolates at 30 and 120 days in the treated and untreated locust bean cake was E.coli only isolated in Kwanar yandaddawa, Staphylococcus aureus were isolated in all the purchased Locust bean cake, Salmonella sp was not detected and a predominant fungal genera were Mucor sp and Rhizopus sp. The result indicated 40% elimination of contaminants at Gude,Jogana and Kwanar yandaddawa. The mean proximate composition percentage differences between 30 and 120 days shows nutritional quality of treated locust bean cake. The Organoleptic assessment indicated that the judges rejected control daddawa due to off flavor. Keywords: African locust bean cake, Ginger extract, Ascorbic acid, Nutritional quality. Received: 12th February, 2018 Accepted: 23rd May, 2018 8 UJMR, Volume 3 Number 1 June, 2018 ISSN: 2616 – 0668 UMYU Journal of Microbiology Research www.ujmr.umyu.edu.ng The more shelf life a product has, the more marketable it becomes. The use of preservatives makes products stay fresher, longer and give more time for products to be used (Bumpres, 2010). Preservation and preservatives are designed to inhibit/control the activities of spoilage causing organisms in food, a process also referred to as sanitization. Spoilage causing organisms due to their growth and metabolic activities produce by-products, which change the texture, taste, flavor and the aroma of the food. Preservatives by their nature are intended to keep the food devoid of these changes. Preservatives act on both Gram positive and Gram negative food spoilers (Jay, 2000). The general idea of products having preservatives is to increase shelf life and prevent items from spoiling. The more shelf life a product has, the more marketable it becomes. The use of preservatives makes products stay fresher, longer and give more time for products to be used (Bumpres, 2010). Shelf life is the period of time during which the food product remain safe, retain desired microbiology, physical, chemical and sensory characteristics (Ademola et al., (2013). The aim of the research is to determine microbiological quality of fermented African locust bean cake stored under ginger extract and ascorbic acid treatment.

2. MATERIALS AND METHODS

The African locust bean condiment was purchased from local producers at the point of harvest at Gude (Sample C), Tofa Local Government Area, Kano State with the bearing of 120 031N80 161 E/12.0500N8.26, Jogana/Gezawa Local Government Area (Sample D) with GPS N12° 111 30.011 E 008° 421 11.511 elevation 1593ft and KwanarYandaddawa (Sample E), DawakinTofa Local Government Area with GPS N12° 061 12.811E 008° 261 45.111 elevation 1669ft.Laboratory Production of standard Daddawa used as control condiment was done according to the method of Gberikon and Agbulu (2015).In preparing a ginger extract treated daddawa, 8mg of freshly prepared ginger extract was added to 5 g of Daddawa (8mg/5g w/w). For ascorbic acid, treated Daddawa 2.5mg was mixed with 5g of Parkia biglobosaDaddawa (2.5mg/5g w/w),the laborarory control (Sample B) was left untreated (Kolapo et al.,2007). The microbiological quality (Aerobic mesophilic count,Anaerobic mesophilic count,Staphylococcus count and Fungal count) were determined according to the method of FAO (1992). Microorganisms associated with Daddawa product were isolated and characterized according to the methods of FAO (1992 ). The proximate analysis of African locust bean cake was conducted according to the procedure of AOAC (2000). The Sensory Quality of the products were determined according to 9 – point Hedonic scales (David, 2005).

3. RESULTS AND DISCUSSION

It was observed that there was microbial log reduction in the treated African locust bean cake at 120 days and microbial log increase in the untreated (Control) Daddawa (figure 1-8). This is actually due to the fact that the samples treated with ginger extract and ascorbic acid experience moisture reduction which discourage microbial growth and proliferation. Both ginger extract and Ascorbic acid reduced the bacterial load of the stored daddawa samples.These findings are consistent with the works of Kolapo et al., ( 2007) who also observed microbial reduction in the treated locust bean cake and microbial increase in the untreated sample of Daddawa.Isolated and characterized bacterial isolates before treatment were E.coli, Staphylococcus aureus, Mucor sp and Rhizopus sp while Salmonella sp was not present (Table 1). Isolated and characterized bacterial isolates at 30 and 120 days in the treated and control fermented African locust bean cake were E.coli only isolated in Kwanar yandaddawa. The occurrence of E. coli in KwanarYandaddawa might be attributed to use of recent feacally contaminated water in the Daddaw a preparation or could be due to unhygienic activities of the Daddawa/Food handlers Bukar et al., (2009) reported that 5(10.0%) out of 50 food handlers in three small scale industries in Kano Metropolis investigated carried E.coli on their hands. Staphylococcus aureus ( was isolated in all the locally purchased Locust bean cake. The Salmonella sp was not detected in the Laboratory treated, control (laboratory untreated) and purchased Daddawa. Salmonella specie has been reported to be transmitted via water and salmonella carriers as food handlers (Bukar et al., 2012). At 30 days Mucor sp and Rhizopus sp were the predominant fungal species,this is in line with the findings of Rabi et al., (2013), at 120 days Mucor sp and Rhizopus sp were detected only in Control Daddawa. The result indicated 40% elimination of contaminants at Gude, Jogana and Kwanar yandaddawa (Table 2). The proximate composition at120 days shows improvement in the nutritional quality of treated locust bean cake

CONCLUSION

 African locust bean condiment was purchased from local manufacturers at the point of production. Control standard Daddawa was produce in the Laboratory.The local and fermented laboratory control samples were treated with the preservatives and control experiment was left untreated.The quality control indicated microbial log decrease in the treated daddawa while untreated daddawa shows microbial log reduction. Contaminant isolates were identified from locally produced, laboratory treated and untreated (Control) African locust bean cake. The proximate analysis and organoleptic assessment of the purchased, laboratory treated and untreated (control) locust bean cake indicated the effect of Ginger extract and Ascorbic acid which improve the shelf life of processed P.biglobosa seeds by reducing the number of microbial load on the treated samples which could have been agents of deterioration or spoilage and reduce the shelf life.

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