In ternationa l Scholars Journa ls African Journal of Food Science Research ISSN 2375-0723 Vol. 6 (9), pp. 373-377, September, 2018. Available online at www.internationalscholarsjournals.org © International Scholars Journals Author(s) retain the copyright of this article. Full Length Research Paper Evaluation of the quality parameters of malted and unmalted maize and soybean blends Adetuyi, F.O.*, Badejo, O.F., Ikujenlola, A.V. and Omosuli, S.V. Department of Food Science and Technology, Rufus Giwa Polytechnic, P.M.B 1019, Owo, Nigeria. Accepted 11 April, 2017 The complementary blends of maize ( Zea mays L ssp mays) and soybean (Glycine max L Merrill) were stored for a period of 12 weeks. The maize grains were malted by subjecting it to cleaning, washing, steeping, sprouting, drying, desprouting, milling and packaging. A portion of the maize flour was blended with soybean flour at the ratio of 70:30 (malted maize flour: soybean flour; unmalted maize flour: soybean flour). The resulting products were stored in polyethylene and plastic containers. The functional properties (Bulk density, viscosity, water and oil absorption capacity, swelling capacity, peroxide value and least gelation concentration) of the products were determined. The result showed that the bulk density and the peroxide value of both malted and unmalted maize flour reduced significantly (P>0.05) when blended with soybean. The swelling capacities of the malted products were lower than those of the unmalted blends and it also decreased though not significantly (P>0.05) with the period of storage. The malting process reduced the viscosity of the products, however; inclusion of soybean flour increased the viscosity. The viscosity and the peroxide value increased significantly (P>0.05) in the two storage containers as the storage period increased. The result revealed that the packaging materials had no significant effects on the parameters assessed. Key words: Unmalted maize, malted maize, soybean blends, bulk density, swelling capacity, water absorption capacity. INTRODUCTION Complementary foods, in most developing countries, are mainly from cereal with animal protein being used as sup- plements. However, because of the high cost of the animal protein, attempts have been made to look into alternative sources (Obatolu and Cole, 2000). In order to improve the nutrition of children in region of chronic and acute malnutrition, various kind of economical protein-rich plant mixtures are used for different area in Africa (Mosha and Svanberg, 1990) . The combination of such food ingredients often alter the food composition of the food product and may change the functional and sensory pro-perties (Kinsella, 1976). It has been recommended that, for long period of conservation, flour should be stored in closed atmosphere. In this condition, flour acidity in-creases owing to accumulation of a linoleic and linolenic *Corresponding author: E-mail: foluadetuyi@yahoo.co.uk. Tel: +2348034257996. acids, which are slowly oxidized; solubility of gluten pro- tein decreases (Kent, 1978). The hazards to flour in storage include mould and bacterial attack, insect infes- tation, also oxidative rancidity. The optimum moisture content of the storage of flour must be in relation to the length of storage envisaged, and to the prevailing ambient temperature and relative humidity, remembering that due to hygroscopicity, flour will gain or lose moisture to the surrounding atmosphere, unless packed in herme- tically sealed containers (Kent, 1978). Package is a means of providing the correct environmental conditions for food or any other product, in order to protect the pro- duct against any deterioration be it microbiological, chemical or physical in nature (Komolafe, 2005). Previous workers in the field of nutrition and food science and technology had worked on the effects of malting on the quality parameters of complementary food, however, scanty information is available on the effect of storage on the quality parameters of malted maize and soybean blends. The aims of this work were therefore to Adetuyi et al. 374 evaluate the quality parameters of malted and unmalted maize and soybean blends and also to determine the effect of storage in polyethylene and plastic container on the qualities of the blends, because these are the com- mon storage containers readily available to greater popu- lace of Nigeria. MATERIALS AND METHODS Maize (Zea mays L ssp mays) and soybean (Glycine max L Merrill) grains used for this work were purchased from ‘Oja Oba’ market in Akure, Ondo state. The maize grains were malted using the method described by Kulkarni et al. (1991) for cereal germination with some modifications. The maize was soaked for 12 h in a volume of water three times its weight and drained. It was spread on a wide wooden box for germination under ambient temperature (30± 2 0 C) for 72 h and watered twice daily. The germinated grains were washed and dried to a moisture content of 10%. It was then milled using ham- mer mill. The unmalted maize grains were washed and dried to a moisture content of 10% and were milled using hammer mill. The soybean flour was also produced according to the method of Kulkarni et al. (1991). The soybean seeds were cleaned and wash- ed. They were boiled for 30 min and later soaked for 24 h with the changing of soaking water at 4 h interval. The testa on each grain was removed and the seeds were dried. The dried soybean seeds were milled into powder using hammer mill. It was formulated thus: unmalted maize 100% (Umm); 70% unmalted maize + 30% soybeans (Umms); malted maize 100% (Mm); 70% malted maize + 30% soybeans (Mms). The formulations were divided into two each. One part was stored in polyethylene bag while the other was stored in a plastic container for 12 weeks at room temperature of 30±2 0 C. The functional and the physicoche- mical properties were determined every three weeks during the storage period. All determinations were done in triplicates. The bulk density was determined according to the method described by Okaka and Potter (1977). The bulk density was calculated as mass of flour per unit volume (g/cm 3 ). The water and oil absorption capacity (WAC) and (OAC) were determined using the method described by Beuchat (1977). A sample (1 g) each was mixed with 10 ml of distilled water for WAC and 10 ml of oil for OAC and blended for 30 s. The samples were allowed to stand for 30 min and centrifuged at 3500 x g for 30 min at room temperature. The supernatant was decanted. The weight of water or oil absorbed by the flour was calculated and expressed as WAC or OAC. The method of Ukpabi and Ndimele (1990) was used for the swelling capacity. Flour (20 g) was put into a washed, dried and weighed graduated measuring cylinder. 100 ml of distilled water was added and allowed to stand for one hour. The supernatant was discarded and the cylinder with its content weighed to obtain the weight of the net sample. The difference in final to initial volume of the sample gave the swelling capacity on volume basis. The method of Coffman and Gracia (1977) was used in the determination of least gelation concentration. Appropriate sample suspensions were weighed into 5 ml distilled water each to make 2-20% (w/v) sus- pension. The test tubes containing these suspensions were heated for 1 h in boiling water (bath) followed by rapid cooling under running tap water. The test tubes were further cooled for an hour under the running water, the least gelation concentrations (LGC), were determined as concentration when the sample from the inverted test tube did not fall or slip. The viscosity was determined using the Association of Official Analytical Chemists AOAC (1990) method. Ten grams of the sample was mixed with 150 ml of deionized water (heated to 95 0 C for 5-10 min) to gelatinize, it was cooled and the viscosity was measured using the Ostwald vis- cometer. The Pearson (1976) method of analysis was used for the pH analysis, the sample (1 g) was taken in separate test tube and 10 ml of distilled water was added. It was then shaken properly and measured with the aid of Iso-electric pH meter. The peroxide value was determined according to the method of AOAC (1990). Statistical analysis Data collected were subjected to the analysis of variance (SAS, 2002). Mean separation were done where there were significant differrences using Duncan multiple range test procedure as des- cribed in the SAS software. Significance was accepted at P>0.05. RESULTS AND DISCUSSION The results presented in Table 1 showed that the bulk density of the flour from both malted and unmalted maize decreased after it had been blended with soybean flour Umm from 0.77 to 0.66 g/m 3 while Mm from 0.83 to 0.81 g/m 3 . This result agrees with the finding of Akubor and Obiegbuna (1999) . They reported that the bulk density of flour from malted maize and soybeans blend reduced significantly. As the storage period increased, the bulk density reduced in the two storage containers. There was no significant difference (P>0.05) in the bulk densities of the samples during the 12 weeks period of storage in the two storage containers. The reduction in the bulk density of the germinated flours would be an added advantage in the preparation of supplementary foods (Akubor and Obiegbuna, 1999). Low bulk density food is desired where packaging is a serious problem (Ikujenlola, 2008). Swelling capacity is the volume of expansion of molecule in response to water uptake which it possessed until a colloidal suspension is achieved or until further expansion and uptake is prevented by intermolecular forces in the swelled particle (Houssou and Ayernor, 2002). The swelling capacity (SWC) of the malted and unmalted maize increased after it had been blended with soybean. The SWC of the unmalted maize blend (1.0 cm 3 ) was higher than the malted maize blend (0.50 cm 3 ). This result differs from the observation of Ikujenlola and Fashakin (2005) that there was reduction in the swelling capacity of the diet prepared from germinated and unger- minated maize cowpea bean blend. The increase in the swelling capacity could be attributed to the increase in the carbohydrate content of the blend because the carbo- hydrate content of the soy bean might have caused the increase in the carbohydrate content of the blend. The SWC decreased though not significantly (P>0.05), during storage in the two containers under observation for the 12 weeks storage period. Gelation is one of the most important functional pro- perties which determine the suitability of incorporation of a particular substance into food products (Adebowale and Adebowale, 2008). The least gelation concentration (LGC) of the flour increased after the maize (malted and unmalted) had been blended with soybean Umm 6-8 w/v and Mm 4- 8 w/v. Obatolu and Cole (2000) observed reduction in the LGC of cowpea and malted maize blend. The LGC was not consistent in storage but remained the 375 Afr. J. Food Sci. Res. Table1. Bulk density, swelling capacity and least gelation concentration of malted and unmalted maize soybean blend. Parameters Week 0 Week 3 Week 6 Week 9 Week 12 Plastic Polyethylene Plastic Polyethylene Plastic Polyethylene Plastic Polyethylene Plastic Polyethylene Umm 0.77(a)a 0.77(a)a 0.70a 0.70a 0.80a 0.78a 0.68a 0.68a 0.76a 0.74a BD Umm 0.66(b)a 0.66(b)a 0.60a 0.70a 0.80a 0.72a 0.61a 0.60a 0.62a 0.64a g/cm 3 Mm 0.83(a)a 0.83(a)a 0.76a 0.78a 0.80a 0.76a 0.77a 0.73a 0.72a 0.76a Mms 0.81(a)a 0.81(a)a 0.76a 0.78a 0.70a 0.76a 0.67a 0.70a 0.69a 0.72a Umm 0.80(b)a 0.80(b)a 0.60a 0.30a 0.80a 0.80a 0.60a 0.60a 1.00a 0.60a SWCUmms 1.00(a)a 1.00(a)a 0.70a 0.60a 0.80a 0.60a 0.60a 0.60a 0.80a 0.60a cm 3 Mm 0.40(b)a 0.40(b)a 0.40a 0.30a 0.60a 0.40a 0.80a 0.80a 0.50a 0.40a Mms 0.50(b)a 0.50(b)a 0.30a 0.80a 0.60a 0.60a 0.60a 0.80a 0.60a 0.50a Umm 6(b)a 6(b)a 6a 6a 4a 6a 6a 6a 4a 6a LGCUmms 8(b)a 8(b)a 8a 8a 6a 8a 8a 8a 6a 6a w/v Mm 4(c)a 4(c)a 4a 4a 8a 6a 6a 6a 6a 6a ms 8(a)a 8(a)a 8a 8a 6a 8a 4a 6a 4a 6a Value represents mean of triplicate. Values with the same letter along the same row are not significantly different (P>0.05) while value with the same letter inside bracket along the column are not significantly different (P>0.05). Umm-Unmalted maize 100%, Umms- 70% Unmalted maize + 30% soybean, Mm- Malted maize 100%, Mms- 70% Malted maize + 30% soybean. BD- Bulk density, SW- Swelling capacity, LGC- Least gelation concentration. Table 2. Water absorption capacity and oil absorption capacity of malted and unmalted maize soybean blend. Plastic Polyethylene Plastic Polyethylene Plastic Polyethylene Plastic Polyethylene Plastic Polyethylene Umm 240(b)a 240(b)a 220a 260a 240a 220a 240a 240a 240a 240a WACUmms 280(a)a 280(a)a 240a 260a 260a 260a 240a 240a 240a 240a % Mm 200(d)a 200(d)a 240a 260a 180a 220a 220a 240a 240a 260a Mms 220(c)a 220(c)a 240a 220a 200a 200a 220a 240a 240a 260a Umm 220(a)b 220(a)b 220a 200a 220a 220a 240a 240a 280a 280a OACUmms 160(c)b 160(c)b 260a 260a 240a 240a 260a 240a 260a 280a % Mm 120(d)b 120(d)b 280a 200a 240a 220a 240a 220a 280a 280a Mms 180(b)b 180(b)b 200a 200a 240a 220a 220a 220a 280a 280a Value represents mean of triplicate. Values with the same letter along the same row are not significantly different (P>0.05) while value with the same letter inside bracket along the column are not significantly different (P>0.05). Umm-Unmalted maize 100%, Umms- 70% Unmalted maize + 30% soybean, Mm- Malted maize 100%, Mms- 70% Malted maize + 30% soybean. WAC- Water absorption capacity, OAC- Oil absorption capacity. same in the first 6 weeks; though there was no statistical significant difference (P>0.05) in the values in the two storage containers. Water absorption capacity is important in the develop- ment of ready to-eat-food cereal grains, since a high wa- ter absorption capacity may assure product cohesiveness (Houssou and Ayernor, 2002). The water absorption capacity (WAC) as shown in Table 2 was higher in the unmalted maize (240%) than malted (200%). These values were higher than the value reported by Yusuf et al. (2007) for snake gourd seed flour (130%). The reduc-tion in the WAC of malted maize agreed with the findings of Tatsadjieu et al. (2004) in the study of germination of sorghum. The WAC increased after the maize had been blended with soybean, Umms-280% and Mms-220%. This could be attributed to the added protein from the soybean since protein are mainly responsible for the bulk of the water uptake and to less extent the starch and cellulose at room temperature (Houssou and Ayernor, 2002). The unmalted blends had a higher WAC than the malted blends. This result agreed with the report of Badifu and Ebegonye (1999) and Ikujenola and Fashakin (2005). When the flour was stored for 12 weeks in plastic container and polyethylene, it was observed that there was no statistical significant difference (P>0.05) in fresh samples of week 0 and stored samples week 12.Oil absorption capacity is a critical assessment of flavour retention and increases the palatability of foods (Kinsella, 1976). The oil absorption capacity (OAC) of the flour of unmalted maize (220%) was higher than that of the malted maize (120%). The values reported in this work was higher than the OAC value of snake gourd seed flour (54%) (Yusuf et al., 2007). The OAC reduced in unmalted maize blends while it increased in malted maize blend, also the OAC of malted maize blend 180% was higher than the unmalted maize blend 160%. This result con- forms to the findings of Padmashree et al. (1987), Mosha and Svanberg (1990) and Obatolu and Cole (2000) that Table 3. Viscosity, PH and Peroxide value of malted and unmalted maize soybean blend. Parameters Week 0 Week 3 Week 6 Week 9 Week 12 Plastic Polyethylene Plastic Polyethylene Plastic Polyethylene Plastic Polyethylene Plastic Polyethylene Umm 3.69(b)b 3.69(b)b 3.86b 4.11b 4.36b 4.90a 5.96a 6.32a 6.25a 6.66a VIS Umms 4.16(a)b 4.16(a)b 3.96b 4.62b 4.36b 4.76b 6.10a 6.67a 6.18a 6.76a g/m2 Mm 3.12(c)d 3.12(c)d 3.62b 3.72b 4.06c 4.21c 5.14a 5.70a 6.36a 6.40a Mms 3.46(c)c 3.46(c)c 3.51b 3.57b 3.82b 4.18b 5.11a 5.92a 6.75a 6.82a Umm 6.13(a)a 6.13(a)a 5.69a 5.99a 6.11a 6.14a 5.97a 5.99a 5.88a 5.93a PH Umms 6.01(a)a 6.01(a)a 5.98a 5.93a 6.04a 6.06a 5.85a 5.93a 5.98a 5.57a Mm 5.78(a)a 5.78(a)a 5.77a 5.72a 5.74a 6.76a 5.57a 5.51a 5.56a 5.53a Mms 5.83(a)a 5.83(a)a 5.78a 5.80a 5.83a 5.86a 5.66a 5.69a 5.60a 5.67a Umm 42.50(a)c 42.50(a)c 56.16a 52.16b 48.17b 49.38b 60.14a 50.16b 62.15a 60.16a PVUmms 23.45(b)c 23.45(b)c 26.14c 50.36a 30.10b 40.31a 40.34a 40.38a 41.26a 43.26a Mm 44.76(a)b 44.76(a)b 28.56d 60.14a 36.13c 38.36c 50.11a 49.37b 51.26a 50.17a Mms 24.67(b)d 24.67(b)d 30.28c 33.14c 30.36c 33.18c 48.36b 50.33a 50.18a 52.56a Value represente mean of triplicate. Values with the same letter along the same row are not significantly different (P>0.05) while value with the same letter inside bracket along the column are not significantly different (P>0.05).Umm-Unmalted maize 100%, Umms- 70%Unmalted maize + 30% soybean, Mm- Malted maize 100%, Mms- 70% Malted maize + 30% soybean. VS- Viscosity, PV- Peroxide value. showed increase in OAC of germinated base blends. During storage in two containers, the OAC increased significantly (P>0.05) in the first 3 weeks of storage but there was no significant difference in the OAC of the flour of week 3 to week 12. The viscosity of unmalted maize flour (3.69 g/m 2 ) was significantly higher (P>0.05) than the malted maize flour (3.12 g/m 2 ). This result agreed with the finding of Ayernor and Ocloo (2007) in the study of malted rice. The decrease in the viscosity could be attributed to the action on the starch by the hydrolyzing enzymes that were producing during malting (Ayernor and Ocloo, 2007). However, Badifu and Ebegonye (1999) reported increase in the viscosity of germinated melon kernel flour. Table 3 showed that the viscosity of the unmalted and malted maize products increased after blending with soy bean (Umm: 3.69 – 4.16 g/m 2 , Mm: 3.69 – 4.16 g/m 2 ). The viscosity also increased significantly (P>0.05) as the storage period increased in the two storage containers. The result of the pH showed that there was no signi- ficant (P>0.05) difference in the pH values of the flour from both unmalted and malted maize reduced after it has been blended with soybean, Umm- 6.13, Umms-6.01, Mm- 5.78 and Mms- 5.83. There was no significant (P>0.05) difference in the P H values of both unmalted and malted maize blends in the two storage containers throughout the storage periods. Peroxide value usually used as an indicator of dete- rioration of fats. As oxidation takes place, the double bonds in the unsaturated fatty acid break down to pro- duce secondary oxidation products which indicate ran- cidity (Ihekoronye and Ngoddy, 1985). After blending of the maize (malted and unmalted) with soybean, the pero- xide value decreased significantly, Umm: 42.50 - 23.45 while Mm: 44.76 - 24.67. During storage, the peroxide value increased significantly (P>0.05) in the two storage containers as the storage period increased. This agreed with the observation of Gahlawat and Sehgal (1994) that the peroxide value and fat acidity of weaning food deve- loped from locally available food stuffs increased with increase in storage period. Conclusion It was observed during this work that the two storage containers used behaved similarly, therefore the use of these storage containers has no significant effect on the parameters estimated at the end of the storage period. 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