Effects of starter culture on the Proximate, Antioxidant, Antinutritional and Mineral composition of fermented Parkia biglobosa seeds to produce Iru
Atere AV, Oyetayo VO, Akinyosoye FA
Iru is a fermented condiment obtained from the seeds of Parkia biglobosa. This research was designed to investigate the effect of using different starter culture on the proximate, antioxidant, anti-nutritional and mineral composition of fermented Parkia biglobosa seeds. The raw seeds were dehulled and fermented naturally and by using starter culture of Bacillus subtilis, Lactobacillus plantarum and Leuconostoc sp. for 72h. The bacterial load of the samples fermented with Bacillus subtilis was not significantly different from the naturally fermented with a value of 8.65log10cfu/g. The Parkia biglobosa seeds fermented with L. plantarum had the highest titratable acidity (TTA) (0.113N) and the lowest pH (6.63) after 72 hours of fermentation. The highest protein was recorded in samples fermented with Bacillus subtilis with a value of 40.36%. Only sample fermented with Leuconostoc sp. showed the presence of copper at 0.23mg/g level after fermenting for 72hr. The anti-nutritional factor showed that trypsin inhibitor was 38.02 mg/g in the raw seeds and this reduced to 17.54mg/g after natural fermentation for 72h and was 26.46mg/g in samples fermented with L. plantarum. The least phytate (10.96mg/g) and oxalate (1.03mg/g) concentration were found in sample fermented with B. subtilis. ‘Iru’ fermented with B. subtilis displayed a higher antioxidants property except in 2, 2, azinobis-3-ethylbenzothiazoline-6-sulphuric acid radical (ABTS) where the ‘iru’ fermented with Leuconostoc sp was the highest with a value of 0.0204mg/g. The naturally fermented iru had the highest tannin with a value of 2.87mg/g, the highest saponin was found in iru fermented with L. plantarum with a value of 58.29mg/g. The highest glycosides and terpinoid were found in iru fermented with Leuconostoc sp. The organoleptic analysis showed that the ammonia odour was highest in naturally fermented ‘iru’ followed by that fermented by B. subtilis. The texture showed that ‘iru’ fermented with L. plantarum was much softer compared to others. The acceptability showed that ‘iru’ fermented with B. subtilis and naturally fermented was well accepted by consumers. On the basis of the acceptability as well as the nutritional composition, Bacillus subtilis can be recommended in the fermentation of Parkia biglobosa seeds to produce good quality iru.