Viscosity Of Porridges Research Articles

Physico-chemical and Microbiological Characteristics of Infant Porridges Produced from Infant Flours Containing Millet and Sorghum Malt

Women generally use traditional cereal flour porridges for weaning children, which are products rich in starch but low in protein. These porridges with a heavy, viscous, indigestible consistency are difficult for the child to digest, due to the starch which swells during cooking. To do this, this study was conducted with the aim of formulating twelve porridges of good nutritional value with the incorporation of millet and sorghum malt flours from four infant flours in order to increase the energy density of the porridges. The analysis of the physico-chemical, nutritional and microbiological parameters of the porridges was carried out using standard methods. From the results, it emerged that the best malt flour incorporation rates were 0.125% for 48h millet malt flour and 0.2% for 48h red sorghum malt flour with a viscosity of porridges between 90 and 120 mm/30s. The macronutrient parameters (Carbohydrates: 14,91±0,88% - 34,48±0,40 %/DM; Proteins: 34,59±0,54% - 44,90±0,84 %/DM, Fat: 26,34±0,18% - 39,50±0,57 %/DM) and the energy density (89.41±0.81kcal/100g to 124.54±0.57kcal/100g) were in accordance with the standards for processed cereal-based foods intended for infants and young children. The results of the total amino acids profile showed that Lysine presented the best content (0.166 to 0.285 mg/100g). For all the samples, the best values of macronutrient and energy density values were obtained with millet malt which presented a high diastatic power. It emerged from the microbiology results that all of the samples presented quite satisfactory levels of coliforms (Salmonella, yeasts and molds in accordance with the standards for processed cereal-based foods intended for infants and young children. At the end of the study, the results obtained showed that the use of millet and sorghum malts could be an alternative to improve the nutritional quality and increase the energy density of infant porridge.

Viscoelastic properties of sweet potato complementary porridges as influenced by endogenous amylases.

Sweet potato (Ipomoea batatas L.) roots contain amylolytic enzymes, which hydrolyze starch thus having the potential to affect the viscosity of sweet potato porridges provided the appropriate working conditions for the enzymes are attained. In this study, the effect of sweet potato variety, postharvest handling conditions, freshly harvested and room/ambient stored roots (3 weeks), and slurry solids content on the viscoelastic properties of complementary porridges prepared using amylase enzyme activation technique were investigated. Five temperatures (55°C, 65°C, 70°C, 75°C, and 80°C) were used to activate sweet potato amylases and the optimum temperature was found to be 75°C. Stored sweet potato roots had higher soluble solids (⁰Brix) content in the pastes compared to fresh roots. In all samples, activation of amylases at 75°C caused changes in the viscoelastic parameters: phase angle (tan δ) and complex viscosity (η*). Postharvest handling conditions and slurry solids content significantly affected the viscoelastic properties of the porridges with flours from stored roots yielding viscous (liquid‐like) porridges and fresh roots producing elastic (solid‐like) porridges. Increase in slurry solids content caused reduction in the phase angle values and increase in the viscosity of the sweet potato porridges. The viscosity of the porridges decreased with storage of sweet potato roots. These results provide a possibility for exploiting sweet potato endogenous amylases in the preparation of complementary porridges with both drinkable viscosities and appropriate energy and nutrient densities for children with varying energy needs.

Production of improved infant porridges from pearl millet using a lactic acid fermentation step and addition of sorghum malt to reduce viscosity of porridges with high protein, energy and solids (30%) content

With the aim of improving the safety and nutritional quality of traditional African weaning porridge, the reduction of the viscosity of a high solids fermented pearl millet porridge by addition of sorghum malt (amylase rich flour, ARF) was investigated. The effect of fermentation, cooking, malt addition and recooking on the microflora of, and the survival of an inoculated pathogen were determined. Addition of 5% (w/v) sorghum ARF to the gelatinized millet porridge gave an acceptable viscosity of 2500–3000 cP at a high solid content of 30%. Fermentation inhibited the growth of microorganisms in the porridge and recooking the fermented porridge after sorghum ARF addition further eliminated (<102 c.f.u./g) the moulds and coliforms that were introduced with the sorghum ARF. The recooked, fermented millet plus sorghum ARF porridge prevented the proliferation of the inoculated Escherichia coli and reduced it to <102 c.f.u./g within 18 h. The porridge could supply children under 3 years with the daily required protein using 1.4 feedings per day and required energy with 4 feedings a day.

Effect of irradiation, with and without cooking of maize and kidney bean flours, on porridge viscosity and in vitro starch digestibility

AbstractAfrican traditional weaning foods are usually prepared from starchy flours at a total solids content of 50–100 g l−1, giving a viscosity of 1000–3000 cP which is consumable by infants. These porridges have very low energy and nutrient densities. Processing to reduce the porridge viscosity and improve the energy and nutrient density may help in solving this problem. Maize, kidney bean and their 70:30 composite flours were irradiated at 0–10 kGy at room temperature. Irradiation greatly reduced the viscosity of porridges, probably by starch depolymerisation. Irradiation improved the starch digestibility of raw bean flours, possibly either by inhibiting α‐amylase inhibitors or by weakening the thick cell walls that enclose the starch granules, thus improving accessibility to enzymes. However, in raw maize, cooked maize and cooked bean flours there was maximum starch digestibility at a dose of 2.5 kGy, followed by small but significant decreases in starch digestibility at higher doses, more so in maize than in bean flours. The decrease in digestibility could be due to the formation of inhibitors of amylolytic enzymes (Maillard reactions products) or to the formation of resistant starch. Irradiation doses required to increase the total solids content of traditional maize‐ and/or bean‐based weaning porridges to at least 200 g l−1 do not compromise starch digestibility significantly.© 2001 Society of Chemical Industry

Effect of refining and supplementation on the viscosity and energy density of weaning maize porridges

The study was undertaken to establish the extent to which use of refined maize flour in weaning porridges affects the viscosity and the energy density of the resulting porridges. Maize porridges from both refined and whole flours were made using modified traditional methods and the viscosity of the porridges was measured using a rotational viscometer. Other factors that might influence the viscosity outcome of the porridges such as flour concentration, supplementation with energy-rich foods, cooking time, temperature at the time of measurement simulating feeding temperature and shear speed were included at three levels per factor (low, medium and high) in a Central Composite Design. Overall, refined flour porridges had significantly (P ≤ 0.0001) higher viscosity than whole flour porridges. Increasing concentration and cooking time significantiy (P ≤ 0.0001, P = 0.0003, respectively) increased the viscosity of the maize porridges while addition of groundnut, addition of cow's milk and increased shear speed had the desired effect of reducing the viscosity of the porridges (P ≤ 0.0001, P = 0.001, P = 0.0002, respectively). The energy density of the porridges as determined from the proximate values of the raw ingredients showed that refined flour porridges had an average of 4% less energy density than the whole flour porridges at equivalent influencing factors. These results show that refined flour produces porridges of significantly high viscosity (stiff consistence), making it practically impossible for the mothers to increase the energy density of the porridges through addition of more flour. Maize flour for use in weaning porridges should therefore be only moderately refined to avoid the high viscosity/low energy density problems associated with over-refined flours.

Optimising viscosity and energy density of maize porridges for child weaning in developing countries

The energy density of traditional starch-based weaning foods used in many developing countries is a major constraint in ensuring adequate energy and nutrient intake for infants and young children. Viscosity and energy density of weaning foods are inextricably linked but studies investigating the two and their interrelationships are scarce. In this study, the factors influencing the viscosity and energy density of weaning maize porridges were investigated in a 28 fractional factorial experiment. The factors investigated included: flour particle size (coarse or fine), concentration (6 or 8%), cooking time (5 or 10 min), temperature at time of measurement (30 or 40°C), shear speed (256 or 512 rpm), shear time (20 or 60 min) and addition of energy-dense foods; groundnut paste replacing 25% of the maize flour (w/w) and/or pasteurised cow's milk replacing 10% of the water (v/v). The viscosity of the maize porridges was significantly increased by increased concentration and cooking time (P ≤ 0.0001) and use of flour of fine particle size (P = 0.002). Increased shear speed and addition of groundnut paste and/or pasteurised cow's milk significantly (P ≤ 0.0001) reduced the viscosity of the porridges. Overall, milk decreased the viscosity of the porridges by 26.0%, groundnut by 56.1% and milk plus groundnut by 64.9%. The energy density of the porridges was significantly (P<0.0001) increased by increasing concentration and addition of groundnut and/or milk. Averaging the two concentrations, the energy density of the porridges was increased by 11.5%, 25.0%, and 36.4% by the addition of groundnut, milk and groundnut plus milk, respectively. These results indicate that the viscosity of weaning maize porridges can be reduced and the energy density increased by variation of some physical parameters and supplementation with energy-rich foods. The results have important implications for the amelioration of protein-energy malnutrition in children in developing countries.