Radial Growth Phase of Aspergillus Species in Selected Food Substances (Tomato, Onion, Pepper and Carrot) at Different Temperatures

Abstract

This study was carried out to determine the effect of temperature on radial growth phase of Aspergillus spp. Aspergillus niger was isolated from apparently spoilt samples of onion, tomato and carrot. These food samples were obtained from different locations. Isolation of A. niger was done using Potato Dextrose Agar (PDA). A. niger which was inoculated at the centre of the PDA plate was observed for radial growth for a period of seven days at 12 hourly interval, twice daily at 28⁰C and 37⁰C respectively. It was generally observed that A. niger grew better at 28⁰C than at 37⁰C, though there were some exceptions observed in carrot (from Jos), which had a radial growth of 0.80cm and 4.25cm at day one and  three respectively. Tomato (from Benin) had a radial growth of 0.85cm at day one, and 4.55 cm at day six. Spring onion also had growth of 1.00cm and 3.80cm at day one and four respectively. Statistics showed that the P-value for the growth of A. niger was 0.0192 at 28^oC and 0.0275 at 37^oC which suggest that radial growth at both temperatures were significant (P <0.05). Having this study in mind, vegetables should be stored at very low temperatures to prevent food spoilage by this organism.This study was carried out to determine the effect of temperature on radial growth phase of Aspergillus spp. Aspergillus niger was isolated from apparently spoilt samples of onion, tomato and carrot. These food samples were obtained from different locations. Isolation of A. niger was done using Potato Dextrose Agar (PDA). A. niger which was inoculated at the centre of the PDA plate was observed for radial growth for a period of seven days at 12 hourly interval, twice daily at 28⁰C and 37⁰C respectively. It was generally observed that A. niger grew better at 28⁰C than at 37⁰C, though there were some exceptions observed in carrot (from Jos), which had a radial growth of 0.80cm and 4.25cm at day one and  three respectively. Tomato (from Benin) had a radial growth of 0.85cm at day one, and 4.55 cm at day six. Spring onion also had growth of 1.00cm and 3.80cm at day one and four respectively. Statistics showed that the P-value for the growth of A. niger was 0.0192 at 28^oC and 0.0275 at 37^oC which suggest that radial growth at both temperatures were significant (P <0.05). Having this study in mind, vegetables should be stored at very low temperatures to prevent food spoilage by this organism.