Effects Of Processing Techniques On Chemical, Functional And Microbial Properties Of Two Varieties Of Lima Bean (Phaseolus Lunatus) And Maize (Zea Mays) Flours And Sensory Properties Of Their

Abstract

This study evaluated the effects of different domestic food processing techniques on the

nutrients, antinutrients, food toxicants composition, functional properties, microbial types and

sensory properties of food products based on two varieties of lima bean (Phaseolus lunatus).

Black and dark red varieties of lima bean were purchased, cleaned, cooked, soaked, dehulled,

germinated, fermented and milled into fine flours. Both the unprocessed and processed flours

were analysed for microflora composition, chemical, functional and sensory properties using

standard methods. The 48h fermented maize and lima bean flours that had traces of hydrogen

cyanide (HCN) were selected because they had the best nutrient profiles in a ratio of 70:30

(protein basis) to formulate composite flours for moi-moi and akara production. Two local

dishes (oshoto and ikpaki) were prepared from whole unprocessed lima bean and maize. The

data were statistically analyzed using percentages, means and standard deviation. Duncan’s

new multiple range test was adopted to separate and compare means. The 3 and 9h soaking as

well as 48h fermentation increased protein in black lima bean (26.07, 26.68 and 32.67%,

respectively). On the other hand, dehulling and cooking, 6 and 9h soaking, 72, 96 and 120h

germination as well as 48h fermentation increased protein in dark red lima bean. These

treatments equally decreased fat, ash and fibre in both varieties. Carbohydrate was increased

in both varieties. Dehulling, cooking and 24h fermentation increased zinc in black and

decreased it in dark red variety. Processing decreased copper, iron and phosphorus in black

lima bean. Dark red lima bean whose cooking water was drained and replaced had decreases

in copper relative to the control. Iron and phosphorus decreased regardless of treatments.

Treatments slightly increased folate in dark red lima bean flours except for 72h germinated

and 48h fermented samples. Phytate, hydrogen cyanide (HCN), trypsin inhibitor and saponin

were reduced in both varieties. Tannins and haemagglutinin levels increased in germinated

samples. Foam and oil absorption capacities decreased in both varieties due to treatment.

Water absorption capacity increased in both varieties except for the black variety fermented

for 24h and 120h germinated dark red variety. Emulsion capacity decreased in black variety

except for 9h soaked, 72 and 120h germinated flours relative to the control. Emulsion

capacity increased in red variety except for the 48h fermented sample. Protein decreased in

both composites relative to their controls, except for the 48h fermented black lima bean and

maize blend. Fat increased in black lima bean and maize flour blends, except for equal value

for the cooked composite relative to the control (1.60%). Ash and fibre decreased in

composites of both varieties. The decrease was much more in dark red variety. Carbohydrate

values for the composites increased regardless of varietal differences. Mineral levels in

composite flours differed (P < 0.05). Zinc and copper increased in both varieties relative to

their controls except for Cu of 96h germinated and 48h fermented black lima bean

composites. Iron increased in the composites of both varieties except for the cooked and 72h

fermented black lima bean composite. Phosphorus increased in black composites except for

the cooked and 72h fermented composites. Both moi-moi and akara from 48 and 72h

fermented varieties and 48h fermented maize blends had increased protein relative to the

control. Fat, fibre, ash and carbohydrate of moi-moi and akara from both varieties were

slightly higher than their controls. Calcium, magnesium, potassium, phosphorus and iron of

both products had increases, except for a few products. Cooking and dehulling of both

varieties caused drastic decrease in pathogenic microflora than the other methods.

Organoleptic attributes and general acceptability of moi-moi and akara from both varieties

improved due to processing. The protein, fat, ash, fibre and carbohydrate content of

traditional dishes (oshoto) prepared with cooked whole lima bean and maize were higher than

those cooked without maize (ikpaki) regardless of varietal differences. Calcium, magnesium,

potassium, phosphorus and iron values for traditional dishes containing maize were higher

than in the dishes prepared without maize. Organoleptic attributes of dishes from blends of

lima bean and maize were slightly lower than the dishes prepared without maize. Domestic

food processing techniques, especially cooking and fermentation increased macro and

micronutrients, decreased antinutrients and food toxicants in lima bean. Organoleptic

attributes of both dishes and products were highly acceptable. Processed lima bean flours and

products have diversified food use to reduce food insecurity.