SENSORY PROPERTIES AND MICROBIOLOGICAL STORAGE STUDY ON FERMENTED LOCUST BEAN (IRU) PUREE AND POWDER FORTIFIED WITH NATURAL PRESERVATIVES

AWARUN, DAPO OLORUNFEMI (2022) SENSORY PROPERTIES AND MICROBIOLOGICAL STORAGE STUDY ON FERMENTED LOCUST BEAN (IRU) PUREE AND POWDER FORTIFIED WITH NATURAL PRESERVATIVES. Masters thesis, Landmark University, Omu Aran, Kwara State.

Text Awarun Dapo Olorunfemi project dissertation olojede final correction 17-11-22 (Thursday).docx Download (7MB)

Abstract

Iru is a traditional fermented-leguminous condiment, which can be made from Locust bean seed, soya beans, melon, and castor seed. Locust bean is majorly found in the grassland of Nigeria and other parts of Africa. Although iru is commercialized it is characterized by short storage life, resulting in off smell, bad taste, and unpleasant texture. Iru puree and powder were produced from wet-milled and dry-milled fermented locust bean seeds, respectively. Natural preservatives i.e., 5% of garlic, 5% of ginger, 5% of turmeric, and a 5% combination of the three spices were added to the samples. Benzoic acid (0.1%) and samples without preservative addition served as the control. The nutritional, sensory attributes and microbiological shelf-life products were determined using standard methods. The results were statistically analyzed using ANOVA at α0.05, and Duncan's multiple range test. There were significant differences (p < 0.05) in the proximate compositions of the iru puree and powder samples. The iru puree fortified with garlic had the highest dry matter, crude protein, carbohydrate, and energy values of 42.39%, 12.04%, 26.80% and 172.50 kcal/g, respectively. While, iru puree samples with the lowest proximate compositions were samples fortified with garlic with dry matter (42.39%), puree with ginger with crude protein (7.84%), puree with the combination of the three spices had carbohydrates (1.56%), and energy values of (66.03%). Iru powder with the highest value for crude protein (40.96%) was the sample with ginger addition and the sample with turmeric had the highest carbohydrate (42.01%). The sample preserved with no preservative the had highest energy value (570.09 kcal/g). The lowest values for crude protein (28.11 %) and energy (484.84 kcal/g) for iru powder samples were found in those with turmeric, while the sample with no preservative had the least carbohydrate (13.77%). The iru puree samples had a range of sensory values with significant differences i.e., appearance (6.07-7.27), aroma/smell (6.37-7.40), and color (6.43-7.30) but not in its overall acceptability of (6.40-7.00). The iru powder samples had a range of sensory values that had significant differences i.e., appearance (7.27-7.57), aroma/smell (6.93-7.77), and color (7.43-7.77) but also not in the overall acceptability (7.13-7.47). The microbial count of iru puree and powder samples varied during the period of storage (25 days). Iru puree had a total aerobic bacteria count that varied from 8 log CFU/mL to 15 log CFU/mL, while the powder counts ranged from 8.5 log CFU/mL to 11 log CFU/mL. The total LAB count of puree samples varied from 4.5 log CFU/mL to10 log CFU/mL on and the powder samples count varied from 4 log CFU/mL to 6.2 log CFU/mL. The total coliform bacteria count of iru puree varied from 5 log CFU/mL on day 25 to 9 log CFU/mL on day 5 and for powder, 5.2 log CFU/mL on day 15 to 8.4 log CFU/mL on day 15. These results show that fortification of iru puree and powder with natural preservatives has the potential to enhance the nutritive, and sensory value of the iru puree and powder samples and help to increase the shelf life of the condiment. Keywords: fermented locust bean seed, iru puree, iru powder, ginger, garlic, turmeric

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