Influence of Bioprocessing Methods on 'China Rice' (Gawal R1), and Soyabean Supplementation on the Quality of Complementary Food

Sources of Materials

Chinese rice (In Nigeria, the rice cultivar often referred to as “China rice”, called Gawal R1) and soybean (Glycine max) were obtained from recognised distributors in Nigeria.

Cleaning and Production

Cleaning and germination of rice as described by Bristone, et al. [15] and Gasinski, et al. [18]. Milling and solid-state fermentation of rice were carried out according to standard procedures [16, 17, 19, 20, 21, 22]. However, one hundred and twenty grammes (120 g) of raw rice flour (RRF) was added to 60.75 ml [16] and was gently mixed for 2 minutes. While soybean was processed into flour as described by Badau, et al. [7] and Bristone, et al. [16].

Complementary Food Formulations

The protein content of the non-complemented rice flours and that of soybean were first determined, and these values were used as a basis for calculating the appropriate mixing ratios. The quantity of rice to soybean in the mixtures was computed using a material balance [16]. This was done to obtain 16% protein in each sample, as recommended by the United Nations Protein Advisory Group [23]. The first four (4) samples were non-complemented rice, comprising Non-Malted Non-Fermented China Rice (NMNFRC), Malted Non-Fermented China Rice (MNFRC), Non-Malted Fermented China Rice (MNFRC), and Malted–Fermented China Rice flour (MFRC). The second set of samples (4) consisted of rice products supplemented with soybeans. They were designated as Non-Malted Non-Fermented China Rice Complemented with Soybean (NMNFRCS), Malted Non-Fermented China Rice Complemented with Soybean (MNFRCS), Non-Malted Fermented China Rice Complemented with Soybean (MNFRCS), and Malted– Fermented China Rice Complemented with Soybean (MFRCS) as shown in Table 1.

Analysis

Determination of moisture, protein (total N × 6.25), ash, fat (Soxhlet extraction method), ash (incineration in a muffle furnace for 24 h at 550 oC) and crude fiber (sample digestion with diluted acid and alkali) as described by Chinma, et al. [24], while energy by Atwater factor {Protein: 4 kcal/g (17 kJ/g), Fat: 9 kcal/g (37 kJ/g); Carbohydrates: 4 kcal/g (17 kJ/g)} as described by FAO [25]. Magnesium (Mg), calcium (Ca), zinc (Zn), potassium (K), iron (Fe), Copper (Cu), and manganese (Mn) in the samples were determined using an atomic absorption spectrophotometer. In contrast, Phosphorus (P) was determined by the photometric method [22]. Amino acid composition was determined by using Applied Biosystem Phenyl Thiohydantoin (PTH) Amino Acid Analyser (Model 120A, PTH Applied Biosystems Inc., USA) [15]. Amino acid score was calculated using the ratio of a gram of the limiting amino acid in the food to the same amount of the corresponding amino acid in the reference diet multiplied by 100. The scoring patterns were based on the FAO/WHO [26] method, as reported by Caire-Juvera, et al. [27].

Sensory analysis was conducted using selected panellists of 21 mothers (20-35 years of age). The sample and the testing place were prepared using standard methods [7, 28]. A 9-point Hedonic descriptive scale (from “1 = dislike extremely to 9 = like extremely”) was used to rate sensory attributes of samples [7, 28].

Statistical Analysis

Statistical analysis was conducted on the raw data generated from the study. One-way analysis of variance (one-way ANOVA) and separation of means by Duncan’s Multiple Range Test (DMRT) at a 5% significance level were performed by using IBM SPSS Statistics version 22.

Proximate Composition

Table 2 shows the proximate composition of the formulated rice-based complementary food products. The protein, fat, ash, crude fibre, moisture and carbohydrate contents ranged from 8.30 (MNFRC to 9.45% (NMFRC), 1.07 (NMNFRC) to 2.12% (MFRC), 0.78 (MNFRC) to 0.92% (NMNFRC), 0.93 (MFRC) to 1.37% (NMNFRC), 3.92 (NMFRC) to 8.53% (MNFRC), and 79.36 (MNFRC) to 83.31 (MFRC) %, respectively. NMNFRC had the lowest energy (362.94 Kcal) while the highest energy was recorded by MFRC (387.12 Kcal). Among the ingredients used for complementary formulations, soybeans had the highest (p < 0.05) protein, fat, ash and crude fiber contents.

Malting and the combination of solid-state fermentation significantly (p < 0.05) reduced the protein content of China rice, but fermentation alone had no effect. The effect of malting and fermentation varied substantially with the proximate composition of malted and fermented rice. However, protein, fat, carbohydrate, and energy values increased, while ash, crude fiber, and moisture content decreased. Similarly, the proximate composition of the formulated rice products varied significantly (p < 0.05) except for protein (Table 3). The results obtained in this study are in line with the reports of other scientists [16].

It has been shown that the addition of soybean flour to all rice samples improved their proximate composition (Table 3) significantly (p < 0.05). It was shown in their average total (8.30 to 16.36 g/100 g protein, ash (0.78 to 1.62 g/100 g), crude fiber (0.93 to 2.63 g/100 g), moisture (8.31 to 8.53 g/100 g), carbohydrate (68.57 to 83.31 g/100 g), and energy (362.94 to 388.88 KJ). Therefore, as can be seen, children will consume a large quantity of non-complemented rice to obtain 16% protein, compared with soybean-complemented products. This has the potential to benefit from consuming protein-complemented starchy products, especially in a society where cases of protein-energy malnutrition are pronounced.

Mineral Content

Zinc, Calcium, Potassium, phosphorus and Manganese contents varied significantly (p < 0.05) among the samples Table 2. However, Iron, Magnesium and contents did not differ significantly (p > 0.05) among the formulated samples. The addition of soybean significantly (p < 0.05) improved the mineral content of the complementary food Table 3 compared with when only China rice was used Table 2. Sensory Scores of Complementary Food Formulations.

1Each value is a mean of quadruplicate determinations. 2Mean values in a row not sharing common superscript letters are significantly (p < 0.05) different 3Formulations: VI (NMNFRCS); Non-malted - non fermented China rice-based food product complemented with soybean, VII (MNFRCS); Malted - non fermented China rice-based food product complemented with soybean, VIII (NMFRCS); Non-malted fermented China rice-based food product complemented with soybean, IX (MFRCS); Malted-fermented China rice-based food product complemented with soybean.

The sensory attributes of complementary food formulations from mixtures of non-malted, malted, fermented, and malted-fermented China rice (Gawal R1), and soybean flours are presented in Table 4. Germination of China rice did not affect the taste of the complementary food formulations, but fermentation, and the combination of fermentation and malting, did. The aroma, texture, and consistency of complementary food formulations from mixtures of malted and fermented China rice and soybeans did not differ significantly from those of the control. However, the combination of malting and fermentation significantly reduced these parameters (p < 0.05). However, colour was not affected by any of the processing methods of complementary food formulations. The overall acceptability of complementary food formulations has been affected by fermentation, and the combination of malting and fermentation of China rice.

1Each value is the mean of 21 times the determinations. 2Mean values in a column not sharing common superscript letters are significantly (p < 0.05) different 3Formulations: VI (NMNFRCS); Non-malted - non fermented rice-based food product complemented with soybean, VII (MNFRCS); Malted - non fermented rice-based food product complemented with soybean, VIII (NMFRCS); Non-malted fermented rice-based food product complemented with soybean, IX(MFRCS); Malted-fermented rice-based food product complemented with soybean.

Amino Acid Composition

The amino acid profile of the complementary food was affected by malting, solid-state fermentation, the combination of malting and solid-state fermentation, and the addition of soybean Table 5. Germination significantly (p < 0.05) reduced the essential amino acids (leucine, lysine, isoleucine, valine, tryptophan, methionine + cysteine, threonine and histidine) but did not affect phenylalanine + tyrosine. Similarly, fermentation alone reduced the levels of essential amino acids (leucine, lysine, isoleucine, phenylalanine + tyrosine, valine, tryptophan, methionine + cysteine, threonine, and histidine). The combination of germination and solid-state fermentation did not affect leucine, lysine, isoleucine, valine, tryptophan, methionine + cysteine, threonine, and histidine but reduced phenylalanine + tyrosine. Fortunately, most of the essential amino acids encountered in the study were within recommended values. Similar trends were observed for non-essential amino acids Table 5.

1Each value is a means of triplicate determination. 2Mean values in a row not sharing common superscript letters are significantly (p < 0.05) different 3Formulations: VI (NMNFRCS); Non-malted - non fermented rice-based food product complemented with soybean, VII (MNFRCS); Malted - non fermented rice-based food product complemented with soybean, VIII (NMFRCS); Non-malted fermented rice-based food product complemented with soybean, IX (MFRCS); Malted-fermented rice-based food product complemented with soybean, *FAO/WHO [29]

Amino acids are the basic unit of protein, which is needed for healthy growth, development and body maintenance [30, 31]. Amino acids play a significant role in regulating multiple processes related to gene expression, including modulating the functions of proteins that mediate messenger RNA (mRNA) translation [31]. If amino acids are deficient, protein synthesis does not occur, protein deficiency diseases set in, and death may result [31]. In fact, without essential amino acids in our diets, there could have been no human or animal life.

In this study, it was observed that the amino acid composition of rice improved significantly upon the addition of soybean, compared with the amino acid composition of milled rice reported in the literature [32]. Studies by Asma, et al. [33] on development of weaning food from sorghum supplemented with legumes and oil seeds, and those of Ijarotimi and Keshinro [34] on formulation and nutritional quality of infant formula produced from germinated popcorn, Bambara groundnut and African locust bean flour as well as nutritive values of three potential complementary foods based on cereals and legumes blends investigated by Marian [35] showed low levels of amino acids compared to this study. Similarly, reports by Onabanjo, et al. [36] on complementary foods from cassava and soybean revealed lower levels of amino acids than in this study. Therefore, children consuming an appropriate combination of rice and soybean as complementary food would have a greater advantage than those consuming other alternatives of cereals and legumes combination.

Amino Acid Scores

Table 6 shows the amino scores for four weaning food formulations analysed in this study, based on the essential amino acid content and the pattern for children aged 1-2 years (% of the FAO/WHO UNU recommendation) as reported by Caire-Juvera, et al. [27].

1Each value is a mean of triplicate determinations. 3Formulations: VI (NMNFRCS); Non-malted - non fermented rice-based food product complemented with soybean, VII (MNFRCS); Malted - non fermented rice-based food product complemented with soybean, VIII (NMFRCS); Non-malted fermented rice-based food product complemented with soybean, IX (MFRCS); Malted-fermented rice-based food product complemented with soybean A lower score for any of the essential amino acids designates the limiting quality of the amino acid, and it gives an indication of the percentage protein quality relative to the reference amino acid as described by Asma, et al. [33]. Asma, et al. [33] reported that leucine was the most limiting amino acid in most blends (58-75%), contrary to the current findings. Also, mostly lysine, threonine, valine and tryptophan are the limiting amino acids in their study. Marian [35] found that the most limiting amino acids were tryptophan, phenylalanine, and tyrosine. The current study is much better in amino acid scores. However, amino acids may be limited in some diets but may fulfil their functions in the body due to their nutritional bioavailability [37, 38, 39, 40].