Functional properties of uda (Xylopia aethiopica) and uziza (Piper guineenses) spiced akamu powder correlated with the paste proximate composition intended for Nigerian postnatal mothers

Abstract

This study explored the influence of spicing akamu powder and paste with uda and uziza on the viscosity and mouth feel of the gruel for postnatal mothers in Nigeria. White and yellow maize were separately spiced during steeping (72 h) and milling. The slurry obtained was dewatered to obtain the spiced pastes. Half paste of each batch was oven dried at 60°C and milled. Functional properties of dried akamu pastes, proximate composition of the paste and their correlation factors were conducted with standard analytical methods. The functional results were; water absorption capacity (142.33–149.50 g/ml), oil absorption capacity (104.64–118.60 g/m), emulsion activity (20.52−31.21%), foam capacity (12.45–17.27%) and least gelation capacity (4.00–8.00). Proximate results were; moisture content (47.03–47.12%), crude protein (7.06–7.40%), fat (1.92–2.42%), fibre (3.31–3.49), ash (2.18–2.23%) and carbohydrate (36.07–38.28%). Both functional and proximate compositions were improved and correlated significantly at 0.01% levels.The use of both spices is feasible for spicing akamu powder production for postnatal mothers.

Keywords:

• Functional property
• proximate composition uda uziza
• akamu

1. Introduction

Pap or akamu is an age long local generic name for semisolid paste and gruel prepared with cereals (maize, sorghum, and millet). It is also known as eko, agidi, or koko in Nigeria. The ones made specifically from sorghum are referred to as ogi-baba. It is a staple food in most parts of African countries with varying preparation methods and names according to locality. It is often taken by nursing mothers as it is believed to encourage breast milk supply and a good vehicle for nutrients for the sick, elderly and convalescent since it is easily digestible (Afolayan et al., 2010).

The traditional preparation of akamu involves steeping of the dried maize grains (white or yellow) in water for 72 h with daily changing of steep water followed by wet milling, sieving, allow to sediment for 24 h, decanting and dewatering the sediment to obtain the semisolid paste. The bran, hulls and germs retained on the sieve were discarded as animal feed (Ijabadeniyi, 2007).This preparation method is restricted to definite localities or ethnic groups (Abdulrahaman & Kolawole, 2006). Steeping allows the grains to be hydrated; enzymes mostly in the aleurone were activated to modify the starch, develop the flavour and reduce the pH. Akamu is fairly acidic (pH 4.8), which tends to inhibit the growth of some bacteria but has the tendency to spoil due to high moisture content (Ladunni et al., 2013). Its spoilage however, is enhanced by some extrinsic factors like storage temperature. Therefore, extension of its shelf life involves refrigeration, freezing and drying to reduce the moisture and microbial load. Addition of some plant materials also serve as preservatives as they contain some microbistatic active ingredients that are microbicidal (Ogbona et al., 2013). Uda and uziza with their antiseptic properties could as well preserve the paste.

The colour of the akamu paste depends on the type of cereal used in the preparation. When white maize is used, it has a creamy or white appearance (Ajanaku et al., 2013). When the paste is dissolved to light consistency with cool water and gelatinized with hot water, it turns into a semi solid gruel called akamu which can be served with protein rich foods such as boiled cowpea (Mohamed et al., 2011), akara or bread. Typically, the carbohydrate rich pap is usually served as weaning food for infants, breakfast for children and convenient meal for its convalescence (Ajanaku et al., 2013).

Uda (Xylopia aethiopica) and uziza (Piper guineenses) are local herbs which are commonly used as spices, stimulants and flavouring agents mostly in South Eastern states of Nigeria (Mosango et al., 2015; Uzodike & Onuoha, 2015). Their proximate composition justified nutrient contributions to diets. Zaragozá (2016) reported proximate composition of 9.59% moisture, 6.97% ash, 13.89% protein, 9.28% fibre, 7.81% fat and 52.94% carbohydrate for uda. While Okonkwo and Ogu (2014) reported 12.35% moisture, 6.33% ash, 5.86% protein, 8.79% fibre, 9.89% fat and 57.32 carbohydrate for uziza. Their high fibre content aids in digestion, water absorption from the body, bulky stool and prevention of constipation due to high fibre content. Also, higher fat content will contribute fat soluble vitamins and energy needed for the lactating mothers. They are protein sources needed for replacement of worn out tissues. Their carbohydrate content is a good energy substrate. Besides, uziza has high mineral content such as calcium, zinc, magnesium, copper and potassium (Idris et al., 2011) with appreciable protein and carbohydrate contents (Okonkwo & Ogu, 2014). More so, uziza contains vitamin C, vitamin A and traces of vitamins B₁, B_2, and vitamin E (Chibuzor & Assumpta, 2014). Both spices are commonly used in ethno-medicine in West Africa due to its protective effect of their phytochemicals and their associated antioxidant properties alongside health benefits of the vitamin and mineral.

Uda (Xylopia aethiopica) which belongs to the family of Annonaceae is also known as African guinea pepper or Ethiopian pepper. It has anti-microbial effects against gram positive and negative bacteria and their phytochemicals have antioxidant properties. These properties are exploited in hot pepper soups (postpartum tonic) prepared for postnatal and lactating mothers as anti-infection and lactation aid in the traditional set ups. Other uses include cough remedy, treating rheumatism, stomach ache, arthritis, inflammations condition and antipyretic (fever reducing) (IIusaya et al., 2012; Uzodike & Onuoha, 2010). The seed extract assist in the contraction of the uterus in post-partum women (Omodamiro et al., 2012). Antioxidant properties of therapeutic plants are preferred to synthetic compounds which are associated with side effects and toxic properties that challenge health (Omodamiro, 2014). The role of the antioxidants is to neutralize the excess free radicals, to protect the cells against their toxic effects. They also contribute to disease prevention by donating electron to the free radical to become stable.

Uziza which belongs to Piperaceae family is a West African spice plant commonly called “Ashanti pepper”. It is named uziza in Igbo and iyere in Yoruba. Other common names are black pepper, Benin pepper, Guinea pepper and false cubeb (Elizabeth et al., 2016). It also has high commercial, economical, and medicinal values. Leaves, roots and seeds extract are used as an adjuvant for the treatment of bronchitis, gastrointestinal disorders rheumatic pains (Okon et al., 2014) and weight control in Eastern part of Nigeria (Okoye & Ebeledike, 2013). Alcohol extract of the seed is active against some parasite, while animal study on the extract revealed increase in hemoglobin level (white and red blood cells) and significant contraction of smooth muscles presumably due to phytochemical, protein, vitamin and mineral content (Nwankwo et al., 2014). In some part of Nigeria, the seeds are consumed by women after child birth to enhance uterine contraction for expulsion of placenta and others from the womb. The seeds can be added to the food of lactating mothers during postpartum period as it encourages or stimulates uterine contraction and return of uterine muscles to the original shape (Lai & Roy, 2004). The aim of this study is to explore the effects of uda and uziza spicing on the functional properties of dried akamu paste and proximate composition of the paste for postnatal women.

2. Materials and methods

2.1. Source of raw materials

Uda seeds (Figure 1a), uziza seeds (Figure 1b), white (Figure 1c) and yellow maize (Figure 1d) were purchased from Ubani main market in Umuahia North Local Government Area of Abia State, Nigeria.

Figure 1. a. Uda, b.Uziza, c. White maize, d. Yellow maize.

2.2. Sample preparation

2.2.1. Preparation of akamu pastes from maize co-fermented with spices

Both sorted white and yellow maize samples were separately steeped each with 5 g of the spices (100 g maize per 5 g spice) in clean stainless steel bucket with tap water for 72 h without changing the water. Thereafter, the water was drained, the maize washed and wet milled with a locally fabricated attrition mill into slurry that was sieved with sterile muslin cloth. The filtrate obtained was allowed to stand for 2 h to sediment so as to achieve sufficient draining of the supernatant water. The thick slurry sediment was dewatered by packing it into a muslin bag and place under a heavy weight for 24 h to obtain the semisolid akamu paste. Half of each paste sample was dried in the oven at 60°C to constant weight, milled and stored in air tight container for functional analysis while the other half was packed in an odour-free container and stored in the refrigerator for proximate composition analysis.

2.2.2. Preparation of akamu pastes from fermented maize spiced at the point of milling

The process above was repeated here but the spices were pulverized and added at the point of milling each maize sample. Half of each semisolid akamu pastes obtained was dried and stored, while the other half was refrigerated as above.

2.2.3. Preparation of un-spiced fermented maize paste

All the processes and storage methods of the spiced samples were repeated here except that there was no spicing. This served as control for each maize sample.

3. Analysis

3.1. Functional analysis

The method described by Ajanaku et al. (2011) was used to determine the water absorption capacity (WAC). The oil absorption capacity (OAC), emulsion capacity (EC) and foaming capacity (FC) were determined with the method described by Bolajoko et al. (2016) and least gelation concentration (LGC) by Suresh et al. (2015) method.

3.2. Proximate analysis

The proximate composition of the paste samples (white and yellow) was analyzed with AOAC (Association of Official Analytical Chemists) (2010) method for moisture content, crude protein, fat, ash and carbohydrate while crude fibre content was determined with the Weende method described by James (1995).

3.3. Statistical analysis

Data obtained were subjected to one-way analysis of variance (ANOVA) using the SPSS version 21.0 software while the Duncan Multiple Range Test (DMRT) was used to separate means at 95% confident level (p < 0.05). Pearson correlation coefficient was used to correlate between functional properties and proximate composition of the dried akamu powder and paste.

4. Results and discussions

4.1. Functional properties of dried akamu pastes

The results are presented in Table 1.

Table 1. Effects of spice type and spicing techniques on the functional properties of dried akamu paste

Sample	Water absorption capacity(g/ml)	Oil absorption capacity(g/ml)	Emulsion capacity (%)	Foam capacity (%)	Least gelation Capacity
FWM	145.06^c ± 0.03	117.26^ab ± 0.01	23.55^de ± 0.21	12.57^c ± 0.04	3.50^f ± 0.12
FYM	147.87^abc ± 0.02	110.22^cde ± 0.05	26.44^bcd ± 0.11	15.04^ab ± 0.05	4.50^de ± 0.04
F(WM+Uda)	148.03^abc ±0.11	115.28^abc ± 0.01	20.52^e ± 0.04	13.51^bc ± 0.09	4.00^ef ± 0.01
F(WM)+G(Uda)	149.50^a ± 0.13	113.11^abcd ± 0.01	22.14^de ± 0.01	13.76^bc ± 0.04	4.00^ef ± 0.04
F(WM+Uziza)	147.04^abc ± 0.01	107.29^de ± 0.03	28.30^abc ± 0.03	14.61^bc ± 0.06	6.00^c ± 0.03
F(WM)+G(Uziza)	147.20^abc ± 0.03	106.39^de ± 0.02	31.21^a ± 0.03	17.15^a ± 0.04	8.00^a ± 0.02
F(YM+Uda)	147.21^abc ± 0.02	118.60^a ± 0.03	24.70^cde ± 0.03	12.43^c ± 0.05	4.00^ef ± 0.06
F(YM)+G(Uda)	148.45^ab ± 0.02	116.41^abc ± 0.01	22.47^de ± 0.01	12.72^bc ± 0.03	5.00^d ± 0.09
F(YM+Uziza)	145.32^bc ± 0.03	104.64^e ± 0.03	30.44^ab ± 0.11	17.14^a ± 0.04	7.00^b ± 0.10
F(YM)+G(Uziza)	142.33^d ± 0.02	110.67^bcde±0.01	28.41^abc ± 0.14	17.27^a ± 0.02	7.50^ab ± 0.11

Values are means of triplicate determinations ± standard deviation. Means in the same column with different superscript are significantly different at (p≤ 0.05) FWM-Fermented white maize only, FYM-Fermented yellow maize only, F(WM+Uda)-Fermented white maize and uda, F(WM)+G(Uda)-Fermented white maize and pulverized uda, F(WM+Uziza)-Fermented white maize and uziza, F(WM)+G(Uziza)-Fermented white maize and pulverized uziza, F(YM+Uda)-Fermented yellow maize and uda, F(YM)+G(Uda)-Fermented yellow maize and pulverized uda, F(YM+Uziza)-Fermented yellow maize and uziza and F(YM)+G(Uziza)-Fermented yellow maize and pulverized uziza

4.2. Water absorption capacity (WAC)

The WAC (147.87 g/ml) of the YM (control) was significantly (p < 0.05) higher than that of the WM (WM) counterpart (145.06 g/ml). Conversely, all the WAC values of spiced dried akamu paste (DAP) produced from YM (142.33–148.45 g/ml) were significantly (p < 0.05) lower than those of WM counterparts (147.04–149.50 g/ml). This could be ascribed to maize variety (differential amylose/amylopectin ratios) and molecular structure (Adegunwa et al., 2011). Besides, nutrient-nutrient interactions between the spices and YM (Okwunodulu & Okwunodulu, 2016) may have been more compared to WM enhanced by the granular sizes of the powders (Akalu et al., 1998). Also, WM DAPs spiced with uda had higher WAC values than those from uziza spiced YM especially when its pulverized part was added at the point of milling (149.50 g/ml). Probably, uda may have contained more proteins with more hydrophilic molecules that must have trapped most of the free water thereby increased their affinity for water. All the WAC values of DAPs from the WM spiced with uda were significantly higher than the control. The YM DAPs spiced with uda irrespective of the spicing techniques were higher than those spiced with uziza and slightly lower than the control. Therefore, for optimal WAC, spicing either of the maize varieties with uda is the best option especially when added pulverized at the point of milling of fermented white maize. The WAC of DAP is the volume of water needed to form gruel with a suitable thickness for child and maternal feeding (Mbata et al., 2009).The DAP of WM spiced with uda may likely digest faster with better refreshment due to higher ability to absorb water, improves handling (Giami, 1993), mouth feel, reduced viscosity (Oyarekua & Adeyeye, 2004) and enhanced acceptability compared to YM spiced with uziza. The WAC of DAPs is influenced by maize and spice type and spicing technique.

Similar WAC results were reported for yellow and white maize varieties used for akamu paste production by Adegunwa et al. (2011).The values obtained in this study were higher than 41.50–44.50% reported by Mbata et al. (2009) for fermented maize “ogi” blended with Bambara groundnut, 1.01–1.24% reported by Ogori et al. (2020) for acha-tamba based ogi enriched with hydrolyzed soy peptides and 40.07–42.25% reported by Ajala and Taiwo (2018) for study on supplementation of “ogi” with oyster mushroom flour. The variations could be traced to the blending materials.

4.3. Oil absorption capacity (OAC)

The OAC is the ability of the food proteins to physically bind fat by capillary attraction. The OAC of DAP from WM control (117.26%) was significantly (p < 0.05) higher than 110.22% from that of YM. The OAC of all the DAPs spiced with uda were significantly (p < 0.05) higher than those spiced with uziza for both WM (113.11–115.28%) and YM (116.41–118.60%) varieties. But that of YM was higher especially when fermented with the spices. Fermentation may have decreased the oil content to the extent of increasing the OAC. Also, uda may have contained more oil than uziza that bound the dispersed protein and modified starches during fermentation to improve oil absorption. This is justified by the significant (p < 0.05) higher OAC (116.41–118.60%) of uziza spiced paste compared to the control (110.22%). Oil improves the mouth feel, eases swallowing and retains flavour (Stevenson et al., 2007). The values obtained in this study was higher than 1.10–1.91% reported by Ogori et al. (2020) for acha-tamba based ogi enriched with hydrolyzed soy peptides and 0.80–1.05% reported by Olusola (2014) for akamu produced from different maize varieties. Theodore et al. (2009) reported 190.00% for taro ogi flours and Sathe et al. (1982) 167.00% for lupin seed ogi flour which was higher than the values reported in this study may be due to the material types used.

4.4. Emulsion activity (EC)

The EC of YM control paste (26.44%) was significantly (p < 0.05) higher than 23.55% from WM. This assertion may have been the reason why the EC of DAPs from YM spiced with uziza (28.41–30.44%) and uda (22.47–24.70%) were higher than WM DAP spiced with uziza (28.30–31.21%) and uda (20.52–22.14%). A higher rate of increment in the EC was observed in the fermented YM blended with uziza (30.44%) and uda added pulverized at the point of milling (31.21%). Only those DAPs spiced with uziza for both maize varieties were significantly improved more than their controls. Emulsion capacity determines the maximum amount of oil that can be emulsified by protein dispersion (Mohamed et al., 2011). Uziza may have dispersed maize proteins than uda to improve their ability to stabilize emulsion. Therefore, EC improvement does not only depend on maize variety, but also on the spices especially uziza irrespective of the spicing techniques. Uziza may have contained more proteins (Okonkwo & Ogu, 2014) than uda which implied good emulsification ability. Protein is the surface active agent that can form and stabilize emulsion by creating electrostatic repulsion on oil droplet surface (Kaushal et al., 2012). Emulsion activity can be greatly increased when highly cohesive films are formed by the absorption of rigid globular protein molecules that are more resistant to mechanical deformation. Higher EC is desired for better consistency, mouth feel and acceptability of the gruel.

4.5. Foam capacity (FC)

Foam capacity is the foaming ability index of dispersed protein. Foam decides texture but it is affected by processing methods, type of raw material and pest infestation (Onimawo & Akubor, 2005). The FC of YM control DAP (15.04%) is significantly (p < 0.05) higher than 12.57% from WM. This could explain the reason why all the FC values of uziza spiced DAP from YM (17.14–17.27%) were higher than their WM counterparts (14.61–17.25%) most especially when added pulverized at the point of milling. Also, all the DAPs spiced with uziza had higher FC than the uda spiced counterparts especially when added pulverized at the point of milling irrespective of maize varieties. Uziza may have contained more protein and carbohydrate (Okonkwo & Ogu, 2014) than uda. The proteins may have been hydrolyzed and dispersed more during fermentation compared to when added pulverized at the point of milling. Besides, grinding may have caused more surface denaturation of protein content of uziza than uda and reduced the surface tension of the molecules at the water air interface. This results in continuous formation of cohesive film around the air bubbles in the foam (Kaushal et al., 2012), that gave uztza a better foaming ability than uda (Onimawo et al., 2007). These therefore implied that maize and spice types as well as spicing techniques had significant influence on the foam capacity of the dried akamu paste. Foaming is not desired in the gruel as it will result in inadequate feeding.

4.6. Least gelation concentration (LGC)

Spicing with uziza and technique used significantly (p < 0.05) improved the LGC of the DAPs more than with uda. The improvement was more when added pulverized at the point of milling. As the LGC is the least protein concentration required by food to form self-supporting gel, uziza may have contained more protein with better gelation capacity than uda. More so, grinding may have increased the surface area of the uziza protein which in turn necessitated faster LGC improvement unlike fermenting before milling which hydrolyses same. Besides, the bio-preservative effect of uziza (Anumudu et al., 2020) may have slowed fermentation thereby resulting in little or no protein hydrolysis for more to be available to aid gelation. Other nutrients of the uziza and both maize varieties alongside their interactions may have contributed to the LGC variations (Yadav et al., 2012). Therefore, significant (p < 0.05) LGC improvement depends on the spice types and the spicing technique. Higher LGC of uziza spiced DAPs most especially with pulverized spice implied less thickening effect (Edet et al., 2016) and therefore ideal for baby food. The LGC values of the DAPs obtained in this study were within 3.50–8.00% reported by Ogori et al. (2020) for acha-tamba ogi enriched with hydrolyzed soy peptides.

4.7. Proximate composition

4.7.1. Moisture content (MC)

Proximate results as presented in Table 2 revealed no significant (p < 0.05) MC variation between the paste samples from the WM (47.02%) and YM (47.01%) controls. This notwithstanding, the MC values of uda spiced akamu pastes from YM (47.11–47.12%) were higher than their WM counterparts (47/03–47.10%) irrespective of the spicing technique. Conversely, the MC of the uziza spiced paste do not follow same trend. Dry spicing with uda had an edge over co-fermentation for both maize varieties unlike with uziza. The higher MC from ground spicing over co-fermentation could be ascribed to nutrient-nutrient interactions (Okwunodulu & Okwunodulu, 2016) that may be more when the pulverized part was added unlike co-fermentation which may have reduced the crude protein (CP) that could have bound more water (Sanful et al., 2010). This was validated by higher MC of all the spiced paste samples than their respective controls. Therefore, maize variety, spice type and spicing technique were responsible for MC variation. Conversely, higher paste MC of the co-fermentation with uziza irrespective of maize variety could be that uziza may have had higher bio-preservative potentials (Anumudu et al., 2020) that may have slowed fermentation thereby making more protein available to bind the available water. The MC of the entire akamu paste (47.01–47.12%) is higher than 11.92–13.10% reported by Ajanaku et al. (2013) for ogi fortified with groundnut seed, 8.40–9.79% for corn ogi spiced with ginger and cinnamon (Emelike et al., 2020), 6.54–11.20% for ginger, uda and clove spiced ogi (Eke-Ejiofor & Beleya, 2017) and 8.68–10.47% for corn ogi (Kiin-Kabari et al., 2018). The MC discrepancies may be due to materials used and the processing techniques employed. Higher paste MC is an indication of poor shelf stability and must be refrigerated.

Table 2. Effects of spice type and spicing techniques on the proximate composition of the akamu pastes (%)

Samples	MC	CP	Fat	Fibre	Ash	Carbohydrate
FWM	47.02^b ± 0.017.	17^e ± 0.05	1.94^c ± 0.01	3.32^bc ± 0.01	2.21^abc ± 0.01	38.62^a ± 0.11
FYM	47.01^b ± 0.01	7.03^f ± 0.01	2.09^b ± 0.02	3.31^c ± 0.02	2.22^ab ± 0.01	38.38^a ± 0.09
F(WM+Uda)	47.03^b ± 0.02	7.17^e ± 0.02	2.41^a ± 0.03	3.32^bc ± 0.02	2.20^abc ± 0.03	37.89 ^ab±0.01
F(WM)+G(Uda)	47.10^a ± 0.03	7.06^f ± 0.01	2.42^a ± 0.05	3.31^c ± 0.03	2.20^abc ± 0.02	37.63^ab ± 0.01
F(WM+Uziza)	47.11^a ± 0.03	7.22^c ± 0.01	2.35^a ± 0.03	3.35^bc ± 0.03	2.19^bc ± 0.03	37.79^ab ± 0.01
(WM)+G(Uziza)	47.03^b ± 0.04	7.18^de ± 0.03	2.30^a ± 0.04	3.49^a ± 0.04	2.21^abc ± 0.02	37.80^ab ± 0.01
F(YM+Uda)	47.11^a ± 0.10	7.40^a ± 0.04	1.92^c ± 0.04	3.42^ab ± 0.01	2.18^c ± 0.01	0138.00^ab ± 0.02
F(YM)+G(Uda)	47.12^a ± 0.03	7.29^b ± 0.03	2.13^b ± 0.04	3.37^bc ± 0.01	2.23^a ± 0.02	37.89^ab ± 0.03
F(YM+Uziza)	47.10^a ± 0.05	7.21^cd ± 0.02	2.09^b ± .03	3.35^bc ± 0.02	2.21^abc ± 0.02	36.07^b ± 0.06
F(YM)+G(Uziza)	47.06^ab ± 0.07	7.19^cde ± 0.02	1.95^c ± 0.04	3.32^bc ± 0.02	2.20^abc ± 0.02	38.29^ab ± 0.06

Values are means of triplicate determinations ± standard deviation. Means in the same column with different superscript are significantly different at (p≤ 0.05). FWM-Fermented white maize only, FYM-Fermented yellow maize only, F(WM+Uda)-Fermented white maize and uda, F(WM)+G(Uda)-Fermented white maize and pulverized uda, F(WM+Uziza)-Fermented white maize and uziza, F(WM)+G(Uziza)-Fermented white maize and pulverized uziza, F(YM+Uda)-Fermented yellow maize and uda, F(YM)+G(Uda)-Fermented yellow maize and pulverized uda, F(YM+Uziza)-Fermented yellow maize and uziza and F(YM)+G(Uziza)-Fermented yellow maize and pulverized uziza

4.8. Crude protein (CP)

The CP content of the akamu paste from WM control (7.17%) is significantly (p < 0.05) higher than that of YM (7.03%) probably due to varietal differences. Protein values of the entire spiced akamu pastes (7.03–7.40%) were significantly (p < 0.05) improved irrespective of the spicing technique, but those spiced by co-fermentation with the spices were higher. This could be traced to nutrient increment by fermentation with little or no nutrient-nutrient interactions despite the bio-preservative effect of the spices. Milling with pulverized spices may have encouraged more protein-calcium interactions due to larger surface area that leads to nutrient depletion (Barclay, 2011). Also, the protein content of all akamu pastes from WM spiced with uda was significantly (p > 0.05) higher than those from their YM counterparts and reverse was the case with uziza spicing. This could be substantiated by higher CP of WM than YM. Therefore, maize variety, spice type and spicing technique were responsible for protein improvement and the associated health benefits. With this, spicing should be encouraged as akamu is generally low in protein which is one of the building blocks of life and essential for growth and development hence the need for enrichment (Kolawole et al., 2017). Co-fermentation of maize with spices could complement the body’s need of these essential nutrients for growth and development, essential for the survival of human being (Voet et al., 2008). The CP values obtained in this study (7.03–7.40%) were within the range 4.11–14.70% obtained by Ajanaku et al. (2013) for ogi fortified with groundnut seed and 5.13–8.01% for clove, uda and ginger spiced ogi (Eke-Ejiofor & Beleya, 2017), but higher than 6.37–5.13% reported by Emelike et al. (2020) for ginger and cinnamon spiced corn ogi. The CP obtained in this study could easily meet 23–56 g/d recommended by FAO/WHO/UNU (1994) to meet the protein needs of the human body, combats protein deficiency and protein energy malnutrition. Consumption of 300 g and above per day which is feasible will meet the protein need. Therefore, spiced akamu is a good protein source.

4.9. Fat

Fat is energy dense food component that contains fat soluble vitamins (A, D, E and K). It contributes to mouth feel, texture, flavour and enhances the general quality of food (Stevenson et al., 2007). The fat content of the akamu paste from control YM (2.09%) was significantly (p < 0.05) higher than that of WM (1.94%), but both were improved by spicing. There was no significant (p < 0.05) fat content variations among all uda spiced WM pastes regardless of the spice type and spicing technique, but those spiced with pulverized uda were slightly higher and the reverse was the case with uziza. Pulverization may have increased the surface areas of uda for more fat extraction unlike when co-fermented during which the fat was utilized by the fermenting organisms. Lower fat content of WM paste spiced with pulverized uziza could mean that uda had more fat (Brown et al., 2015) than uziza. Same fat trend observed in WM and their spicing technique also repeated in YM pastes. Therefore, maize and spice type as well as spicing technique contributed to fat content improvement of the paste. Fat content values obtained in this study (1.92–2.42%) were within 0.31–10.11% reported by Ajanaku et al. (2013) for ogi supplemented with groundnut seed and lower than 3.76–4.35% reported by Emelike et al. (2020) for ginger and cinnamon spiced corn ogi but higher than 1.00–1.70% from corn starch ogi reported by Kiin-Kabari et al. (2018). The fat improvement in this study is encouraged as fat content of any diet which provides 1–2% of its energy calorie is considered sufficient to humans (Antia et al., 2006).

4.10. Crude fibre (CF)

The CF is non-digestible, non-nutritive and bulking or roughage found in edible portion of plant cell wall. They are insoluble with hypocholesterolemic properties and help in providing roughage that aids in digestion, softening of stool (Ojo & Enujiugha, 2016) and peristalsis movement of foods in the intestine. The CF content of WM control akamu paste (3.32%) was significantly (p < 0.05) higher than that of YM (3.31%). There was significant (p < 0.05) CF improvement of the entire spiced akamu paste samples compared to their respective controls except those samples from WM spiced with uda. Co-fermentation with uda never improved the fibre content (3.32%) while addition of pulverized uda at the point of milling decreased same (3.31%). Spicing WM with pulverized uziza improved the CF content of akamu paste (3.49%) than when co-fermented (3.35%). This increment could be due to direct fibre addition by the pulverized uziza while lower value during co-fermentation could be traced to reduced fermentation due to bio-preservative effect of uziza (Anumudu et al., 2020). Also, uda (has more fibrous seed coats) may have contained more fibre than uziza (Figure 1a). In contrast, spicing YM with uda improved the fibre content of the paste samples more when co-fermented (3.42%) than when added pulverized (3.37%). While with uziza, fibre improved when co-fermented (3.35%) than when added pulverized. The results indicated that maize and spice type as well as spicing technique employed significantly (p < 0.05) influenced the dietary fibre of the akamu paste. Therefore, spicing in this study is desired considering the health benefits of fibre. Fibre has been reported to offer a variety of health benefits and is essential in reducing the risk of chronic diseases such as diabetes, obesity, cardiovascular diseases and diverticulitis (Ajani et al., 2012). Fibre values obtained in this study (3.31–3.49%) were higher than 0.29% from ginger spiced ogi and 0.81% from cinnamon spiced ogi (Emelike et al., 2020), may be uda and uziza contained more fibre.

4.11. Ash

Ash is an estimation of inorganic content (mineral) in food (Mamiro et al., 2011).The ash content of akamu paste from YM control (2.22%) was significantly (p < 0.05) higher than that of WM (2.21%). The YM must have contained more mineral than the WM. There was no significant ash variation between akamu pastes from WM spiced with uziza and those from YM spiced with uda regardless of their spicing technique. Therefore, maize and spice types alongside spicing technique had no appreciable ash impute on their DAPs. On the other hand, akamu paste from WM spiced with uziza had maximum ash content (2.21%) when added pulverized at the point of milling than when co-fermented (2.19%). Similarly, the pastes from YM spiced with uda had maximum ash content (2.23%) when added pulverized at the point of milling YM than when co-fermented (2.18%). Maize and spice type as well as spicing technique significantly influenced their ash content. Higher values of ash obtained could be attributed to the addition of pulverized parts of the spices Lower ash content from co-fermentation could be due to mineral leaching during fermentation into water and sieving which results in more loss. Nutrient-nutrient interaction between the spices and the maize which were minimal due to short resident time may have contributed to the higher ash as well. Therefore, addition of pulverized uda at the point of milling favoured ash content improvement of the pastes. Despite this, there was no ash improvement among the entire akamu paste samples except when uda was added ground to YM (2.24%). In spite of this, values obtained in this study (2.18–2.23%) were higher than 0.10–0.84% reported by Ajanaku et al. (2013) for ogi supplemented with groundnut seed and 0.19–0.30% by Emelike et al. (2020) for ginger and cinnamon spiced corn ogi. May be groundnut, ginger and cinnamon used had lower ash content.

4.12. Carbohydrate

There is no significant (p < 0.05) discrepancy between the akamu paste from WM control (38.62%) and YM (38.38%) which also reflected in most of the entire spiced akamu paste irrespective of maize variety, spice types and spicing techniques. Therefore spicing had slight impute on carbohydrate content of the pastes. Slight carbohydrate improvement of co-fermented akamu pastes than addition of pulverized at the point of milling could stem from the antiseptic properties of the spices that may have reduced the rate of carbohydrate hydrolyses unlike addition of pulverized spice. Only the paste from YM spiced with uziza were significantly (p < 0.05) different with addition of the pulverized spice at the point of milling (38.29%) higher than 36.07% from co-fermented YM and uziza. Generally, there was decrease in carbohydrate content in the entire spiced akamu samples compared to their controls which implied that all the spiced APs may likely be less bulky or viscous compared to the control as carbohydrate is a function of bulk density (Okwunodulu et al., 2020).The carbohydrate content obtained in this study were lower than 68.10–86.50% reported by Ajanaku et al. (2013) for ogi supplemented with groundnut seed and 78.93–81.64% by Emelike et al. (2020) for ginger and cinnamon spiced corn ogi.

4.13. Correlation between functional properties of dried akamu powder and proximate composition of their pastes

The results presented in Table 3 showed that only water absorption capacity (WAC) of the akamu powder had significantly positive correlation (r = 0.594) with fat at 0.01 level. This indicated that the drier the akamu powder the higher the fat content due to proportional moisture loss, and the more it will absorb water. With more absorption of water, the more the gruel will swell and increase in volume. Therefore, drying enhances water absorption as justified in Tables 1 and 2. Conversely, WAC had no significant (p > 0.05) positive correlation with moisture, CF, ash but negative correlation with CP and CHO. Protein embeds carbohydrate in its matrix and prevents interaction with water (McWattlers et al., 2003).

Table 3. Correlation between functional properties and proximate composition of akamu paste

	WAC	OAC	EC	FC	LGC	MC	CP	FAT	CF	ASH	CHO
WAC	1
OAC	.254	1
EC	−.420	−.845**	1
FC	−.512*	−.883**	.850**	1
LGC	−.334	−.675**	.775**	.798**	1
MC	.204	−.042	.029	−.077	.076	1
CP	−.051	.298	.020	−.249	.049	.485*	1
FAT	.594**	−.259	−.137	.034	.039	.079	−.411	1
CF	.084	−.154	.403	.175	.395	.084	.431	−.018	1
ASH	.082	.065	−.155	−.065	.055	−.351	−.314	.003	−.114	1
CHO	−.094	.343	−.260	−.273	−.283	−.223	−.095	−.163	−.133	−.011	1

MC- moisture content, CP-crude protein, CF-crude fibre, CHO-carbohydrate, WAC-water absorption capacity, OAC-oil absorption capacity, EC-emulsion capacity, FC-foam capacity and LGC-least gelation capacity. Correlation is significant at the 0.01 level (2-tailed)**. Correlation is significant at the 0.05 level (2-tailed)*

Besides, OAC had positive correlation with CP, ash CHO and negative with MC, fat and CF. The EC had positive correlation with MC, CP, CF and negative with fat, ash and CHO. The FC had positive correlation with fat, CF and negative with MC, CP, ash and CHO. The LGC had positive correlation with MC, CF, fat, CF, ash and negative with only CHO all at 0.01 levels.

5. Conclusion

This study revealed that maize and spice types as well as spicing technique improved the proximate content of the spiced akamu paste and the functional properties of their dried counterpart. Spicing is encouraged since it increased moisture, crude protein, CF and decreased only the paste ash and carbohydrate. Significant (p < 0.01) correlation was only between fat and water absorption capacity while the rest were not significant. Therefore, maize variety, spice types and spicing techniques decided the potentials of the akamu paste for postnatal mothers. Choice of maize type, spicing level and technique for preparing spiced akamu depends on individual.

Acknowledgments

The authors are grateful to the Department of Food Science and Technology for provision of laboratory space and reagents used.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

There was no funding from any person or organization.

Notes on contributors

Innocent N. Okwunodulu

Dr. Okwnodulu, I. N. is a Senior Lecturer in the University.

Anselm U. Onwuzuruike

Onwuzurik is an Assistant Lecturer.

Gladys-Peace U. Chima

Chima, G is a B. Sc holder.

Felicia U. Okwunodulu

Okwunodulu, F. U. is a Senior Lecturer.