EVALUATION OF SOME MICROORGANISMS AND NUTRITIONAL QUALITY ON CORN STEEP LIQUOR PRODUCED FROM TWO VARIETIES OF MAIZE GRAINS.

Abstract

Corn steep liquor (CSL) (‘Omidun’) is an important raw material of high nutritional value and served as a nitrogen source. This study evaluated some microorganisms, antimicrobial activity and nutritional quality on Corn steep liquor from white and yellow maize varieties. The two varieties of white and yellow maize (Zea mays L) purchased at Oba market, Akure, Ondo State, Nigeria were packaged in different sterile polyethylene bag and transported to the laboratory for analysis. The maize were sorted to remove stones, mouldy and deformed grains. They were divided into different portions labelled A –E. Sample A (a whole white maize), B (a whole yellow maize), C (30% white: 70% yellow maize), D (60% white: 40% yellow) and E (50% white: 50% yellow maize). This was steeped for 72 hours with a clean pipe-borne water, wet milled, sieved using different Muslin cloth. After filtrate had been settled, the supernatant (liquor) was taken for analysis for the period of five days. The pH and total titratable acidity (%TTA), enumeration, isolation and characterization of some microorganisms associated with CSL were carried out using standard method. Antimicrobial activities, proximate composition, minerals, vitamins, antinutrients and sensory evaluation of CSL were determined using standard technique. The pH significantly (P < 0.05) reduced from 5.62 to 3.90 while TTA progressively increased from 0.14% to 0.29%. Sample E had the highest lactic acid bacterial count (LABC) of log (9.24) cfu/ml while sample B had the lowest LABC of log (4.22) cfu/ml. Microorganisms isolated from two varieties of maize included Lactobacillus fermentum, Lb plantarum, Lb brevis, Bacillus licheniformis Saccharromyces cerevisiae, Candida kefyr, and Penicillium citreogenum. The highest zones of inhibition of combination of Lb plantarum and S. cerevisiae on ACCT 35218 Escherichia coli and ACCT 14028 Salmonella typhi were recorded as 39 (±0.1) mm and 37 (±0.2) mm respectively. Combinations of Lb fermetum and S. cerevisiae on ACCT 35218 Escherichia coli and ACCT 14028 Salmonella typhi were 38 (±0.2) mm, 34 (±0.1) mm respectively. Mean zones of inhibition of combination of Lb brevis and S. cerevisiae on ACCT 35218 Escherichia coli and ACCT 14028 Salmonella typhi was recorded as 36 (±0.0) mm, 36 (±0.0) mm respectively. Zones of inhibition of CSL are between 10.0 (±1.3) mm and 18.0 (±1.3) mm in sample B and sample E respectively. There was significant difference (P < 0.05) in proximate composition of two varieties of maize. Sample E had the highest value of proximate composition of protein contents 9.6 (±0.1)%, ash 1.8 (±0.4)%, moisture 66.1 (±0.2)%, fat 3.4 (±0.4)% and carbohydrate 19.1 (± 0.4)% while sample B had lowest value of proximate composition of protein contents 6.5 (±0.1)%, ash 1.1 (±0.2)%, moisture 59.6(±0.2)%, fat 1.8 (±0.2)% and carbohydrate 31.0 (± 0.1)%. There was absence of fibre in the two varieties of maize. Vitamins in CSL included Vitamins A, B, C and K while minerals included Ca, Mg Cu, K and Fe. There was absence of phytate and trypsin inhibitors in CSL. Sample E had highest β-Glucosidase, lipase and urease activity as 0.002491 μmol/min, 0.002132 μmol/min and 0.005782 μmol/min respectively. Sample B had lowest values of 0.001107 μmol/min, 0.001322 μmol/min and 0.003621 μmol/min respectively. All the Panelists generally accepted Sample E in terms of colour, texture, flavor and mouth feel. Corn steep liquor can therefore serve as alternative treatment for diarrhea of the rural population as it inhibited the causative organisms used in this study. Further research is needed to optimize the CSL for industrial applications and as well as to adopt technical method to preserve CSL for further use.