Nutritional composition and antinutritional properties of maize ogi cofermented with pigeon pea

Abstract Maize was cofermented with pigeon pea for ogi production and evaluated for nutritional (proximate composition, minerals, vitamins, and amino acid profile analyses) and antinutritional (phytate, tannin, and trypsin inhibitor activity analyses) qualities. White maize and pigeon pea were mixed at ratios of 90:10, 80:20, 70:30, 60:40, and 50:50, respectively, with 100:0 serving as the control. Mixtures were cofermented for 96 hr at 27°C ± 2°C and nutritional, mineral, and antinutritional qualities were analyzed using analysis of variance. Results of proximate analysis showed that the values were significantly difference at p ≤ .05. Maize cofermented with pigeon pea at a ratio of 60:40 had the highest protein (22.79 mg/100 g), fat (19.27 mg/100 g), ash (2.98 mg/100 g), crude fiber (0.73 mg/100 g), and lowest moisture (1.98 mg/100 g) content, and was significantly (p ≤ .05) different from the other ratios. Of all the mixtures analyzed, 60:40 was significantly (p ≤ .05) different and had the highest Vitamin B1, B2, and B3 contents. Amino acid profile results showed that maize cofermented with pigeon pea at a ratio of 60:40 showed the highest contents of lysine (93.95 mg/g), tryptophan (20.38 mg/g), isoleucine (54.78 mg/g), phenylalanine (86.23 mg/g), leucine (109.55 mg/g), and valine (68.29 mg/g), respectively, and was significantly (p ≤ .05) different from the other ratios. Results of antinutritional analysis showed low phytate, tannin, and trypsin inhibitor values in maize cofermented with pigeon pea at a ratio of 60:40 when compared with other ratios. The cofermented maize‐pigeon pea product 60:40 had high amino acid profile than the others.


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OKAFOR et Al. of lysine and tryptophan, contributing to the low content of protein, and trace amounts of B-vitamins (USDA, 2012).

Protein deficiency in infants and young children has been
shown to have harmful effects on the brain and may have longer term effects on brain function (Omemu & Faniran, 2011).
It has been shown to have adverse effects on the immune system, resulting in a higher risk of infections (Bistrian, Blackburn, Scrimshaw, & Flatt, 1975;Omemu, 2011). It also affects gut mucosal function and permeability which, in turn, affects absorption and makes possible bacterial invasion from the gut, which can result in septicemia. Protein deficiency has also been shown to adversely affect kidney function, affecting adversely glomerular and tubular function (Benabe & Martinez-Maldonado, 1998).
Legumes are low-priced sources of protein-rich foods that have been important in alleviating protein malnutrition and in the tropics; they are the next important food crop after cereals (Ashaye et al., 2000;Oyarekua, 2009). Leguminous seeds include soybean, cowpea, groundnut, pigeon pea (red gram), mucuna (velvet beans), jack bean, oil bean, and chicken pea. The legume and grain families are by far the world's most important sources of food; grains supply starch, whereas legumes which include bean, peas, and alfalfa supply protein and fats. Legumes are rich sources of protein, energy, vitamins, dietary fiber, minerals, and oil, especially the oil-seeds (Arawande and Borokini, 2010). Cereals are deficient in lysine and tryptophan, but rich in methionine and cysteine, whereas legumes are deficient in sulfur-containing amino acids such as methionine and cysteine, and rich in lysine (Sodipo & Fashakin, 2011). There is a need to combine the cereals and legumes together so as to complement each other.
Pigeon pea (Cajanus cajan) is a locally available, affordable, and underutilized grain legume of the tropics and subtropics (Fasoyiro et al., 2010). Pigeon pea uses include soil improvement, agroforestry, intercropping, food, feed, wood, and pest management (Valenzuela and Smith, 2002). Pigeon pea is reported to contain 20%-22% protein, 1%-2% fat, 65% carbohydrate, and 6.8% ash (Onweluzo & Nwabugwu, 2009) and rich in mineral quality and fiber content. It is known as "otili" in the South-western part of Nigeria. In South-eastern Nigeria, it is usually consumed in cooked form like cooked beans and most consumers prefer to cook "fio-fio", as it is usually called, with firewood due to the long period of time it takes to soften. The presence of antinutrients in pigeon pea has limited its utilization. Fermentation process had also been utilized to increase the protein and textural qualities of the seeds (Fasoyiro et al., 2010).
The main objective of this study is to evaluate the nutritional and antinutritional qualities of ogi developed from maize and pigeon pea.

| Sample collection
The pigeon pea (Cajanus cajan) and the dried maize grains (Zea mays) used in this study were purchased from Bariga market, Bariga, Lagos State, Nigeria.

| Cleaning and weighing of maize/pigeon pea samples
The grains/pea seeds were sorted to separate them from stones, dirt, etc. Six different proportions of maize: Pigeon peas were weighed as follows

| Fermentation of maize-pigeon pea blends
The grains/peas were washed thoroughly and steeped in tap water in the ratio of 1:2 (w/v) in properly labeled plastic buckets with lids.
Maize-pigeon pea ogi was prepared using a modified traditional Maize-pigeon pea ogi fermentation method (Odunfa & Adeleye, 1985). The different maizepigeon pea blends were steeped for 48 hr, washed, wet-milled, and then sieved using muslin cloth to separate the pomace from the filtrate. The filtrates were allowed to settle and sour for another 48 hr ( Figure 1). During the fermentation (steeping and souring) process, samples were taken at 24 hr interval for microbiological, chemical, nutritional, and antinutritional analysis.

| Nutritional analysis
Samples taken at 24 hr interval throughout the maize-pigeon pea ogi fermentation process were subjected to mineral and vitamin analysis, and amino acid profiling. The minerals analyzed were potassium, phosphorus, calcium, sodium, magnesium, and iron, whereas the vitamins analyzed were vitamins B 1 , B 2 , and B 3 .

| Analysis of minerals
The method of Mbaeyi and Onweluzo (2010) was used in analyzing minerals. Mineral analysis of samples taken from the fermenting maize-pigeon pea ogi at 24-hr interval was determined in three phases: sample preparation, sample digestion, and atomic absorption spectrophotometer (AAS) analysis.

| Sample preparation
Samples that were in grain form collected during the steeping period of fermentation were washed with distilled water and dried in the oven at 70°C for 3 hr. Afterward, they were blended to get grain powders. Samples in slurry form collected during the souring period of fermentation were weighed directly for the analysis. A solution of HNO 3 and distilled water H 2 O in the ratio of 3:1 was used to digest the samples in order to free the mineral from their complex forms.
Standard serial concentrations of pure forms of the minerals were prepared to standardize the AAS before reading the concentration of minerals. Serial dilutions used were 0.5 mg, 1.0 mg, 2.0 mg, 4.0 mg, and 8.0 mg made from 100 mg/100 ml standard flask.

| Sample digestion
Sample (0.67 g) was weighed into a glass beaker and 50 ml of HNO 3 : H 2 O was added to it. The solution was heated in a fume cupboard with Bunsen burner applying gentle heat. The HNO 3 fumes were allowed to escape gradually until no more fumes were seen. This indicated the end of the digestion. The digested samples were then filtered into a 50 ml standard flask and made up to volume with distilled water and ready for AAS analysis.

| Atomic absorption spectrophotometer analysis of digested samples
A standard curve was obtained for each of the minerals using the serially diluted concentration standards using an appropriate lamp particular to a given mineral which was mounted on the AAS. After obtaining the standard curve at a particular wavelength, the digested sample in the container was sucked into the AAS for analysis. At that wavelength which a particular mineral absorbed highest, the molecules were excited and moved to higher energy level. On returning back to their ground state, the excess energy absorbed and given off was observed as the concentration of the minerals. The different minerals analyzed, their lamps and individual wavelengths were potassium (K lamp; 766 nm), phosphorus (P lamp; 213 nm), calcium (Ca lamp; 317 nm), sodium (Na lamp; 589 nm), magnesium (Mg lamp; 279 nm), and iron (Fe lamp; 259 nm).

| Analysis of vitamin B 1 (thiamin)
Vitamin B 1 was analyzed in samples using the AOAC (2005) method.
Accurately weighed 1.5 g of test sample was introduced into a 200 ml volumetric flask; 100 ml of 0.1 N HCL solution was added and the mixture heated in a water bath at 100°C for 30 min. After cooling, the content of the flask was made up to mark with 0.1M HCL solution and mixed thoroughly. The solution was filtered using Whatman No. 1 filter paper. The first 20 ml of the filtrate was discarded. The remaining filtrate (100 ml) was transferred into centrifuge tube containing 0.5 g frankonite powder (a flocculant which precipitate the particles faster during centrifugation) stirred for 10 min using RAM 2718 stirrer, then centrifuged at 5,000 rpm for 5 min to separate layers. The supernatant liquid was discarded while 5 ml of absolute alcohol and 5 ml of the potassium ferric-cyanide solution in sodium hydroxide solution were added after it was previously frozen at 0°C.
A pinkish coloration of mixture was observed after 10 min of mixing, and then 10 ml of toluene solution was added, stirred for 10 min and centrifuged for 10 min at 5,000 rpm. A very clear pink color was transferred to the toluene layer. Thiamine standard (0.5 mg) was prepared and 10 ml of the thiamine standard solution was treated same as sample above. The standard and sample solution was read at 530 nm wavelength using the SP 30UV spectrophotometer (Pye Unican). The amount of thiamine present in each sample was calculated as thus:

| Analysis of vitamin B 2 (riboflavin)
Vitamin B 2 was analyzed in samples using the AOAC (2005) method. Accurately weighed 1.5 g of sample was introduced into 200 ml volumetric flask; 100 ml of acetic acid: water mixture (50:50) was added and heated on a boiling water bath at 100°C for 30 min. The mixture in the flask was cooled to 20°C, then made up to the mark with acetic Thiamine (mg/100 g) = absorbance of sample absorbance of standard × weight of standard (mg) weight of sample (g) × 100 acid-water solution. The mixture was stirred for 10 min using the stirrer and then filtered in the dark. The first 20 ml of the filtrate was discarded, 0.5 mg of riboflavin standard solution was prepared, and 10 ml of the standard solution was transferred into 200 ml volumetric flask and treated similarly as sample above. The fluorescence of the standard and sample solutions was read using spectrophotometer at 460 nm wavelength. The amount of riboflavin in each sample was calculated as follows

| Analysis of vitamin B 3 (niacin)
Vitamin B 3 was analyzed in samples using the AOAC (2005) method.
Hydrochloric acid solution (5 N; 5 ml) was added, and 5.0 ml of dichloromethane and 90 ml of deionized water were added to the mixture, stirred, and heated on a boiling water bath at 100°C for 30 min. It was then cooled and the flask content made up to the mark with distilled water, filtered using Whatman No. 1 filter paper discarding the first 20 ml of the filtrate. The niacin standard solution of 0.5 mg was prepared, and 10 ml of the stock solution was taken and treated same as sample above. The absorbance of the standard and sample solutions were taken at 410 nm wavelength using spectrophotometer and calculation followed thus:

| Amino acid profile determination
The amino acid profile of samples taken from the fermenting maizepigeon pea ogi at 24 hr interval was determined in four phases: the amino acid extraction phase, the chromatographic phase, the quantitative determination of amino acid profile phase, and the colorimetric analysis of amino acid profile phase.

| Extraction of amino acids
Two gram (2 g) samples were weighed using digital chemical balance (model OHAUS precision plus). The samples were blended in a mortar and pestle and transferred into 250 ml beaker. Phosphate buffer solution (0.2 mol/L; 20 ml) pH 7.0 was added. The mixture was stirred for about 3 min and the resulting mixture was centrifuged at 2,000 rpm for 10 min. The supernatant was decanted and poured into separating funnel. The supernatant was shaken three times with 10 ml portion of petroleum ether to remove the organic pigments. The top phase was discarded and the aqueous phase which contained protein and amino acids was retained. Protein was precipitated from the aqueous phase by adding 5 ml of 10% w/v trichloroacetic acid (TCA) to 5 ml extract. The mixture was shaken and kept in the freezer for 10 min. The precipitate formed was removed by centrifugation (2m000g) and the filtrate was used for the amino acid profile determination.

| Chromatographic analysis of amino acids (TLC technique)
The amino acid content in the extract was separated by thin-layer chromatography method (TLC technique). Aliquots of 50 μl of the extracts were spotted on Avicel microcrystalline cellulose thin-layer plates (Whatman analytical plates) along with 20 μl of reference standard mixture. The reference mixture contained lysine, histidine, phenylalanine, methionine, glycine, cysteine, proline, leucine, isoleucine, threonine, tyrosine, valine, arginine, tryptophan, and glutamic acid (BDH and Sigma chemicals), each present at a concentration of 0.1% (w/v). One-dimensional ascending chromatography was done, and the solvent system employed for the separation was n-butanol-glacial acetic acid-water at a ratio of 4:1:2 (v/v). After 4 hr of separation the chromatograms were air-dried and the amino acids were located by spraying with locating reagent, 0.2% (w/v) of Ninhydrin in ethanol. The sprayed chromatograms were allowed to air-dry and later oven-dried at 100°C for 5 min for the spots to be clearly identified. The separated amino acids were identified using the reference standard spotted alongside (Mikes and Chalmers, 1981).

| Quantitative determination of amino acid profile
The quantitative determination of the amino acids (profile) was done through colorimetric method of Rosen (1957)  The squares containing amino acids were cut-out and eluted with 5 ml distilled water at 70°C for 2 hr; the cellulose powder was removed by centrifugation at 5,000 rpm for 5 min. The supernatants were decanted and kept for the colorimetric analysis of amino acid profiles.

| Colorimetric analysis of amino acid profile
The extracts obtained above from the samples were used for amino acid profiles analysis using the modified ninhydrin colorimetric analysis method of Rosen (1957) as reported by Opere et al., (2012). To 1 ml of the diluted extracts of each amino acid was added 0.5 ml cyanideacetate buffer (pH 5.4) and 0.5 ml 3% (w/v) Ninhydrin in methylcellosolve. The mixture was heated in a boiling water bath at 100°C for 15 min. Immediately after the mixture was removed from the water bath, 5.0 ml iso-propyl alcohol-water mixture (ratio 1:1) was added as diluents and mixed by shaking vigorously, then cooled to room temperature (25°C). The amino acid profile was estimated by determining the optical density at 570 nm wavelength using UV/visible spectrophotometer. The blank was similarly treated as sample above and used as the control to set the absorbance to zero (distilled water). The amount of amino acid content was each calculated from the standard curve of known concentration of leucine (10 mg/ml).

| Antinutritional analysis
Samples taken at 24-hr interval throughout the maize-pigeon pea ogi fermentation process were subjected to antinutritional analysis. The antinutrients analyzed were phytate, tannins, and trypsin inhibitors.

| Analysis of phytate
Phytate determination in samples followed the method AOAC (2003).
Phytate was extracted with 0.5 mol/L (HNO 3 ) solution and digested with 0.5 ml of (HClO 4 ) perchloric acid. The digested sample was made up to 25 ml volume with distilled water in a standard volumetric flask.
From this extract, 2.5 ml of sample was taken and added to 2.5 ml of nitric acid, and the phytic phosphorus present in the extract reacted with 2.5 ml of vanadium molybdate (solution) reagent to produce a yelloworange complex. The absorbance (OD) was measured at 460 nm wavelength using a spectrophotometer (P7 UV/Vis spectrophotometer).
The phytate content was then calculated from the 2 mg of phytic acid standard concentration with a reagent blank treated as sample above.

| Analysis of tannin
Tannin content was determined by the AOAC (2005) method. Sample (5 g) was dispensed in 50 ml of distilled water and shaken. The mixture was allowed to stand for 30 min at 28°C before it was filtered through Whatman no.4 grade of filter paper. The extract (2 ml) was dispensed into a 50 ml volumetric flask. Similarly, 2 ml standard tannic solution (0.1 mg/ml tannic acid) and 2 ml distilled water were put in a separate volumetric flask to serve as standard. 2.5 ml of saturated sodium carbonate (Na 2 CO 3 ) solution and 1 ml of Folin-C reagent were added to each flask and volume made up to 50 ml and mixed well.
After standing for 1½ hr, the sample was filtered using Whatman no.4 grade of filter paper and the absorbance measured at 760 nm against reagent blank.

| Analysis of trypsin inhibitor activity (TIA)
Trypsin inhibitor activity (TIA) of samples taken from the fermenting maize-pigeon pea ogi at 24 hr interval was analyzed in two phases: the crude inhibitor (trypsin) was extracted from jatropha leaves before the assay of TIA was carried out.

Extraction of crude inhibitor
Jatropha leaves (50 g) were weighed and cut into pieces. The leaves were homogenized in a blender containing 50 ml of sodium dithionite (0.7% w/v). The homogenate was left to stand for about 1 hr and then filtered through layers of cheese cloth into a beaker and thereafter centrifuged at 1,000 rpm for 5 min to remove fine particles. The resulting supernatant was stored in the refrigerator.

Assay of TIA
Trypsin inhibition activity was assayed by the procedure of AOAC (2005). Sample extract (0.1 ml) and 0.9 ml of 0.1 mol/L phosphate buffer pH 8.0 was mixed with the same volume of trypsin solution and preincubated at 37°C for 5 min; 1 ml of 0.03% (w/v) Bovine Serum Albumin (BSA) was added to the mixture and incubated for 30 min at 37°C after which the reaction was stopped by the addition of 2 ml of 5% (w/v) Trichloroacetic acid (TCA) solution. The mixture was filtered.
To 1 ml of the filtrate, 5 ml of 0.55 mol/L Na 2 CO 3 and 0.1 ml of Folin-C reagent. The resulting color absorbance was determined at 660 nm wavelength. Standard sample was prepared in the absence of inhibitor.
where, T, absorbance in the absence of inhibitor; T°, absorbance in the presence of inhibitor.

| Statistical analysis
Data obtained were subjected to analysis of variance (ANOVA) at

| Proximate determination
Based on the result of the sensory evaluation of the different fermenting maize-pigeon pea ogi blends, the proximate, mineral, vitamin, antinutritional, and amino acid profile analysis were carried out on 60:40 and 70:30 maize-pigeon pea ogi blends with 100:0 serving as control (Table 1).

| Changes in moisture, fat, and ash contents
Changes in moisture, fat, and ash contents of the different fermenting maize-pigeon pea ogi blends are shown in Table 2. At the 0-hr steeping period, the moisture content of 100:0 maize-pigeon pea ogi (1.04%) was the highest and was significantly (p ≤ .05) different from the others. As fermentation progressed, the moisture contents significantly (p ≤ .05) decreased. At 24 hr souring, there was a significant The low moisture content of the different fermented products Changes in the fat content of the different fermenting maizepigeon pea ogi blends were significantly different at the different stages of fermentation. At the 0 hr steeping period, the 60:40 maizepigeon pea ogi (13.36 mg/100 g) had the highest fat content; followed by the 70:30 maize-pigeon pea ogi (9.11 mg/100 g), whereas 100:0 maize-pigeon pea ogi (7.60 mg/100 g) had the least fat content. As fermentation progressed, the fat content significantly (p ≤ .05) increased in all the maize-pigeon pea ogi blends.
There was increase in fat content observed during fermentation in this study. This is in line with Otunola et al. (2007) that showed increases in fat content of maize-ogi fortified with okra seed flour.
Increased fat content was also reported by Mbata et al. (2009). The improvement to the fat content of the fortified ogi products may be due to increase in activity of lipolytic enzymes in the fermentation medium which hydrolyzes fat to glycerol and fatty acids (Modu et al., 2013). The free fatty acids are used by the fermenting organisms for the synthesis of new lipids (Ezeokonkwo, 2004). The fat requirement for neonates is essential for the development of brain especially for children under 2 years of age (Ajanaku et al., 2013

| Changes in crude fiber, crude protein, and carbohydrate contents
Changes in crude fiber, crude protein, and carbohydrate contents of the different fermenting maize-pigeon pea ogi blends are shown in Table 3.  (Okoye, 1992). In this study, crude fiber values were found to be higher in the fortified ogi products (70:30-0.50 mg/100 g; 60:40-0.73 mg/100 g) than in the unfortified ogi (100:0-0.25 mg/100 g). The recommended dietary allowance (RDA) for crude fiber in foods for infants (6-12 months) is 4.0 mg/100 g (FAO/WHO, 1998), implying that the crude fiber contents of the fermented products in this study did not meet the recommended allowance for infants. improved in cereal-legume blends due to the contribution of lysine by legume and methionine by cereal (Wakil & Kazeem, 2012

| Changes in potassium (K), phosphorus (P), and calcium (Ca) contents
Changes in potassium, phosphorus, and calcium contents of the different fermenting maize-pigeon pea ogi blends are shown in Table 4. From this study, it can be observed that addition of pigeon pea to maize in the production of ogi yields fortified products with improved valuable mineral content. This is also substantiated by the increased ash content of the fortified maize-pigeon pea ogi products. Some researchers (Adeyemi & Soluade, 1993;Enujiugha, 2006) also observed significant increase in ash and mineral contents in African oil bean-ogi and pawpaw-ogi, respectively.
Potassium is an essential nutrient needed for maintenance of total body fluid volume, acid and electrolyte balance, and normal cell function (Young, 2001). Low potassium intake has been associated with a lot of noncommunicable diseases including hypertension, cardiovascular diseases, chronic kidney stone formation, and low bone-mineral density in children (WHO, 2003;WHO, 2012 Phosphorus is fundamental to growth, maintenance, and repair of all body tissues, and is necessary, along with calcium and magnesium, for proper growth and formation of bones in infants and children (Heaney and Nordin, 2002). It also functions to buffer body fluids to maintain a normal pH, to temporarily store and transfer energy derived from metabolic fuels, and to activate many catalytic proteins through phosphorylation (Dickinson, 2004 ). It is also important in blood clotting, muscle contraction, and in certain enzymes in metabolic processes (Adeyeye & Fagbohun, 2005). Its deficiency can lead to rickets in children (Oyarekua, 2011b), a reduction in bone mass and the development of osteoporosis (Dickinson, 2004).

| Changes in sodium (Na), magnesium (Mg), and iron (Fe) contents
Changes in sodium, magnesium, and iron contents of the different fermenting maize-pigeon pea ogi blends are shown in Table 5 An increased level of magnesium was also reported in Aremu, Olaofe, et al. (2011) and Aremu, Osinfade, et al. (2011). The recommended dietary allowance (RDA) of magnesium for infants is 350 mg/100 g (Oyarekua, 2011b), and all the fermented products met the RDA except the unfortified product 100:0. Magnesium is the most abundant ion in plant cells. It is needed for many different enzyme systems in the body. It is also important in the formation of adenosine triphosphate (ATP), storage of carbohydrates, fats, and protein, and also needed in nerve and muscle activity, as it maintains electrical potential in nerves (Oyarekua, 2011b).
At the beginning of fermentation (0 hr steeping period), the iron content of the different fermenting maize-pigeon pea ogi blends ranged from 3.68 to 6.72 mg/100 g, with 100:0 maize-pigeon pea ogi having the lowest iron content and 60:40 maize-pigeon pea ogi having the highest. As fermentation progressed, the iron content increased in all set-ups, with a range of 20.89-27.80 mg/100 g at the 48 hr steeping period. It was observed that at the beginning of souring (0 hr souring), the iron content in most of the fermentation set-ups dropped slightly (100:0 and 70:30 maize-pigeon pea ogi blends), but increased afterward. At the 48 hr souring period which marked the end of the fermentation process, the iron content ranged from 14.05 mg/100 g in 60:40 maize-pigeon pea ogi to 15.90 mg/100 g in 100:0 maizepigeon pea ogi.
An increased level of iron at the end of the fermentation period, observed in this study, was also reported in Aremu, Olaofe, et al. (2011) and Aremu, Osinfade, et al. (2011). The recommended dietary allowance (RDA) for iron in infants' foods is ≥10.0 mg/100 g (Adeyeye & Faleye, 2004;FAO/WHO, 1998) and all the fermented products had iron contents within this range. Iron is a component of hemoglobin that transports oxygen to body tissues and is needed for red blood cell synthesis, respiration, and growth. Its deficiency can lead to anemic conditions in children (Dickinson, 2002).

| Determination of vitamin B 1 , B 2 , and B 3 contents
Changes in vitamin B 1 , B 2 , and B 3 contents of the different fermenting maize-pigeon pea ogi blends are presented in Table 6. The result showed that there was significant effect (p ≤ .05) of fortification on the vitamin B 1 , B 2 , and B 3 contents of the different fermenting maizepigeon pea ogi blends.
There was an evident increase in the vitamin B 1 content as fermentation progressed. A slight decrease was noticeable at the beginning of souring but values increased as souring progressed.
This study determined the vitamin B content of maize ogi and the fortified maize-pigeon pea ogi products as according to USDA (2012), maize contains trace amounts of vitamins, especially the B-vitamins.
According to Richardson (1997), the recommended dietary allowance (RDA) of vitamin B 2 for infants is 1.3 mg/100 g. Again, only the fortified products met this requirement. Vitamin B 2 (riboflavin) is a part of the coenzymes, flavin mononucleotide (FMN), and flavin adenine dinucleotide (FAD), needed for oxidation/reduction reactions, including those involved in energy production. Deficiency results in cracks and sores around the mouth and nose, sore throat, magenta tongue, T A B L E 8 Profile of phenylalanine, leucine, valine, and lysine (mg/g) of the different fermenting maize-pigeon pea ogi blends 60:40-6.89 mg/100 g) than the control (100:0-2.21 mg/100 g).
According to Richardson (1997), the recommended dietary allowance (RDA) for infants is 16 mg/100 g and none of the fermented products met the recommended dietary allowance (RDA) for vitamin B 3 (niacin).
Vitamin B 3 is a part of the coenzyme, nicotinamide adenine dinucleotide (NAD) or its phosphate form, NADP that plays a key role in energy production and in the synthesis of fatty acids and steroids. The coenzyme is also involved in DNA replication, repair, and cell differentiation.

| Profile of tryptophan, isoleucine, and methionine
The profile of tryptophan, isoleucine, and methionine of the different fermenting maize-pigeon pea ogi blends is presented in Table 7.
Analysis of variance showed that there was significant effect (p ≤ .05) of fortification on the profile of the above-mentioned amino acids of the different fermentation set-ups.

| Profile of phenylalanine, leucine, valine, and lysine
The profile of phenylalanine, leucine, valine, and lysine of the different fermenting maize-pigeon pea ogi blends is presented in Table  The same trend was also observed for the leucine and valine contents of all the different maize-pigeon pea ogi blends. The leucine

| Determination of antinutritional content
Changes in phytate and tannin content (mg/100 g), and trypsin inhibitor activity (%) of the different fermenting maize-pigeon pea ogi blends are presented in Table 9. There was a massive reduction in antinutritional content of all the fermentation set-ups from the beginning to the end of fermentation. A one-way analysis of variance showed that there was significant difference (p < .05) between the values of the different antinutrient parameters of the different fermenting maize-pigeon pea ogi blends, although the unfortified product (100:0 maize-pigeon pea ogi blend) had much lower values than the fortified products (60:40 and 70:30 maize-pigeon pea ogi blends).
The phytate content at the beginning of fermentation (0 hr steeping) was highest in 60:40 maize-pigeon pea ogi (446.84 mg/100 g) and lowest in 100:0 maize-pigeon pea ogi (90.23 mg/100 g). As fermentation progressed, the phytate content kept decreasing until 13.36 mg/100 g in 60:40 maize-pigeon pea ogi and 2.54 mg/100 g in 100:0 maize-pigeon pea ogi at the 48 hr souring speriod which marked the end of the fermentation process.
Antinutrients have the capacity of decreasing the digestibility and palatability of protein because they form insoluble complexes with them (Mbata et al., 2009). Phytates are known to form complexes with iron, zinc, calcium, and magnesium making them less available and thus inadequate in food samples especially for children. Tannins are naturally occurring plant polyphenols. Their main characteristic is to bind and precipitate protein interfering with its digestion and absorption. It is known that 10-50 mg phytate per 100 g will not cause a negative effect on the absorption of zinc and iron (Pikuda & Ilelaboye, 2013).
In this study, the phytate contents of the different fermentation products at the end of fermentation ranged from 2.54 to 13.36 mg/100 g, which is within the safe consumption range. The tannin content of all the different fermented products in this study are generally low, ranging from 0.3 mg/100 g to 0.44 mg/100 g and are far lower than the lethal dose of 0.7-0.9 mg/100 g (Pikuda & Ilelaboye, 2013). This study showed a reduction in the tannins and phytic acid content, and trypsin inhibitor activity with increased fermentation period. Wakil and Kazeem (2012) also observed reduction in polyphenol contents of cereal-soyabean blends as a result of malting and toasting, and fermented cereal-legume blends, respectively. The reduction in the phytic acid content of formulated blends may be due to hydrolysis of phytate by the enzyme phytase into lower inositol phosphates which are believed to be activated during the fermentation process by organisms (yeasts) whose hydrolyzing ability is enhanced by fermentation (Egwin, Elem, & Egwuche, 2011;Wakil & Kazeem, 2012). Previous reports have shown that lactic acid fermentation can also reduce tannins and phytic acid content, and trypsin inhibitor activity in bread fermentation (Chaoui, Zibilske, & Ohno, 2003;Khetarpaul & Chauhan, 1990).

| CONCLUSIONS
This study showed that the fortified maize: pigeon pea products met the recommended dietary allowance (RDA) for moisture, fat, ash, protein, calcium, phosphorus, magnesium, iron, and vitamins B 1 and B 2 . The fortified maize: pigeon pea products showed a significant decrease in antinutrient contents as antinutrients decrease the digestibility and palatability of proteins by forming insoluble complexes with them. The antinutrient content of all the fortified maize: pigeon pea products were shown to be within the safe consumption range. The fortified maize: pigeon pea products also met the recommended dietary allowance (RDA) for all the amino acids analyzed in this study (tryptophan, lysine, methionine leucine, isoleucine, and valine). It can therefore be concluded that the fortified maize: pigeon pea products 60:40 and 70:30 are safe for use as weaning foods.