COMPARATIVE STUDIES OF TOXIGENIC MYCOFLORA, PROXIMATE AND AFLATOXINS CONTENTS OF GROUNDNUT (ARACHIS HYPOGAEA L.) SEEDS AND CAKE IN NIGER STATE, NIGERIA

Abstract

ABSTRACT Despite economic importance of groundnut, it is vulnerable to contaminations by toxigenic mycoflora. Therefore, this study investigated the associated toxigenic mycoflora, proximate composition and aflatoxin contents of groundnut seeds and cakes (Arachis hypogaea L.) sold in ten (10) markets of Niger State, Nigeria. Eighteen (18) samples of groundnuts seeds and eighteen (18) samples of groundnut cakes were collected across each of the three agricultural zones of Niger State, namely Bida and Mokwa (zone 1), Minna and Shiroro (zone 2), Kotongora and Rafi (zone 3). Isolation of fungal species was done using dilution of 104 factor on PDA. Proximate composition and Aflatoxin content analyses were done following standard procedures. Ninety-three 93 isolates were obtained from groundnut seeds while 166 isolates from groundnut cake and were characterized into five genera: Aspergillus, Fussarium, Penicillium, Rhizopus, and Alternaria. In groundnut seeds, significant difference (p < 0.05) was observed in fungal isolates across the study areas. Significantly, highest isolates were obtained in samples from Bida (27.48 %) while samples from Shiroro (7.27 %) was the least. In groundnut cakes, significantly highest isolates was obtained in samples from Mokwa (25.20 %), while samples from Shiroro (8.33 %) was the least. Significant differences were observed in the proximate composition of groundnut seeds and cakes across all the study areas. The groundnut seeds had the highest moisture contents, crude fat, protein and carbohydrate in Shiroro (4.64 %), Mokwa (47.24 %), Kotangora (22.15 %) and Shiroro (29.27 %) respectively, while in the same order the least percentage was obtained from Minna (2.46 %), Shiroro (41.61 %), Minna (18.48 %), and Rafi (23.37 %) respectively. In groundnut cakes the highest moisture contents, crude fat, protein and carbohydrate in Shiroro (8.89 %), Bida (35.48 %), Minna (34.39 %), and Rafi (43.97 %) respectively, while in the same order the least percentage was obtained from Rafi (3.00 %), Kotangora (16.48 %), Rafi (21.02 %), and Bida (21.16 %) respectively. Correlation results indicated that the moisture content of groundnut cakes showed positive correlation with the protein and carbohydrate content of groundnut seed (5 %). From groundnut seed samples, the highest percentage of Aflatoxin (AfB1) Bida (77.65 µg/kg) and least in samples from Kotangora (1.57 µg/kg). In groundnut cakes samples, the highest (AfB1) (24.43 µg/kg) was obtained in samples from Bida while samples from Minna (9.67 µg/kg) were the least. The results indicate that fungi isolated from this study were toxigenic mould, and AfB1 content of the samples were above the tolerable limits. Therefore, improved management of groundnut seeds is essential in order to ensure a high quality product that will in turn reduce the health challenges associated with consuming contaminated groundnut products.