Effect of Temperature and Fermentation Time on Phytic Acid and Polyphenol Content of Rabadi— A Fermented Pearl Millet Food

Rnbadi was prepared by fermenting a mixture of pearl millet flour and butter milk for three periods of time (3, 6 and 9 hr) at four temperatures (35°, 40°, 45° and 50°C). Temperature had little influence on degradation of either phytic acid or polyphenol content. At all temperatures the phytic acid and polyphenol content decreased with an increase in fermentation time. Nine hour fermentation resulted in maximum reduction of phytic acid (27–30%) as well as total polyphenols (1–12%) at all temperatures. Phytic acid was reduced to a greater extent than polyphenols.     

Effect of natural fermentation on phytate and polyphenolic content and in-vitro digestibility of starch and protein of pearl millet (Pennisetum typhoideum)

Natural fermentation at 20, 25 and 30°C for 72 h brought about a significant reduction in phytic acid content of pearl millet (Pennisetum typhoideum Rich) flour. The phytate content was almost eliminted in the flour fermented at 30°C. An increase in polyphenol content of fermented flour was noticed, the higher the temperature of fermentation the greater was the increase in polyphenol content of pearl millet. An improvement in starch as well as protein digestibility (in vitro) was noticed at all the temperatures of natural fermentation, the highest being at 30°C.     

Phytic acid and extractable phosphorus of pearl millet flour as affected by natural lactic acid fermentation

Lactic acid fermentation of pearl millet flour decreased its phytic acid content and increased extractable phosphorus. Fermentation at 40 and 50°C for 72 h or longer eliminated phytic acid almost completely; extractable phosphorus was more than doubled. Lower temperatures (20 and 30°C) were less effective. The changes in concentration of phytic acid and extractable phosphorus may be attributed partly to phytase activity inherent in pearl millet flour.     

Effect of Temperature and Period of Fermentation on Protein and Starch Digestibility (In vitro) of Rabadi—A Pearl Millet Fermented Food

Rabadi was prepared by allowing pearl millet flour-country buttermilk mixture to ferment for three different periods (3, 6 and 9 hr) at four different temperatures (35°, 40°, 45°, and 50°C). As fermentation time increased, protein as well as starch digestibility (in vitro) of rabadi increased significantly at all the temperatures. Maximum increase in the digestibility of both protein (51%) and starch (58%) occurred after 9 hr fermentation at 45°C.     

Effect of traditional processes on phytate and mineral content of pearl millet

Six pearl millet genotypes were used in this study: IS 91333, IS 91666, and IS 89111 for dough fermentation and IS 880004, IS 91777 and YD-X3 genotypes for Damirga flour. Investigation showed that traditional fermentation for 14 h at 37 °C caused a decline in pH with time; a sharp drop was observed at the beginning, which gradually levelled off. Fermentation resulted in significant reduction of starch and phytic acid: 9.5–9.8% and 43–44%, respectively. Protein content was not affected. The Damirga process significantly elevated starch content (by 8–19%) but significantly reduced the protein and phytic acid contents (by 10.9–12.1 and 86–93%, respectively). Damirga flour was found to retain 25–84% of the major minerals (Ca, Mg, P, K and Na) and 52–65% of the minor minerals (Zn, Mn and Fe); losses occurred for all minerals except Cu.     

Effect of various types of fermentation on in vitro protein and starch digestibility of differently processed pearl millet

Pearl millet (Pennisetum typhoideum) grains were fermented with Lactobacilli and yeast alone, in combination and with natural flora at 30 °C for 48 h after giving various processing treatments viz, fine and coarse grinding, soaking, debranning, dry heat treatment, germination and autoclaving after adding of water. Fermentation was carried out with Lactobacillus acidophilus and Rhodotorula isolated from naturally fermented pearl millet and Lactobacillus acidophilus, Candida utilis and natural fermentation using freshly ground pearl millet flour as inoculum. All the processing treatments except coarse grinding improved the protein and starch digestibility. Autoclaving enhanced the digestibilities of processed samples which was further improved by different types of fermentation, the maximum being in case of germinated and naturally fermented pearl millet. A combination of Lactobacilli and yeast was more effective in increasing the protein as well as starch digestibility as compared to pure culture fermentation.     

Effect of Fermentation by Pure Cultures of Yeasts and Lactobacilli on Phytic Acid and Polyphenol Content of Pearl Millet

Single and mixed pure culture fermentations of pearl millet flour with yeasts and lactobacilli, namely, Saccharomyces diastaticus, Saccharomyces cerevisiae, Lactobacillus brevis and Lactobacillus fermentum, at 30^oC for 72 hr brought about a significant reduction in phytic acid and polyphenols which were present in considerable amounts in pearl millet flour. Reduction in phytic acid was more pronounced than that in the polyphenols.     

Development And Characterization of Extruded Fura From Mixtures of Pearl Millet and Grain Legumes Flours

Dehulled pearl millet flour (100%) and blends of pearl millet, cowpea, groundnut and soybean flours at 80:20, 70:30 were extruded at 30 g moisture/100 g sample using a Brabender Laboratory single screw extruder to develop extruded fura products. The fura extrudates and fura produced in the traditional way were analyzed for their physical and chemical and sensory properties. There were significant differences (p < 0.05) in the puff ratio of the extruded fura products. Pearl millet: cowpea (80:20) fura had the highest puff ratio (4.71) while the pearl millet: groundnut (80:20) fura had the lowest (2.90). The bulk density of the pulverized extruded fura was lower than that of the dried and pulverized traditional fura. The hydration power of the extrudates increased significantly (p < 0.05) at 28°C and 50°C. Extrusion increased the hydration power of products. Fura extrudate containing 100% pearl millet flour had the highest hydration power of 63.9% at 28°C, while the traditional fura had the lowest of 15.8% at 28°C. Protein content of samples increased with supplementation of pearl millet with grain legumes. Sensory evaluation results showed that there were no significant differences among the fura extrudates and the traditional fura with respect to color, texture and overall acceptability except for flavor. Extruded products were still acceptable after 12 weeks storage in polyethylene and cellophane bags at 30 ± 2°C. Extrusion and supplementation processes are therefore one way of producing a convenient shelf stable nutrient rich fura in the areas where fura is commonly consumed.     

Effects of Germination and Pure Culture Fermentation by Yeasts and Lactobacilli on Phytic Acid and Polyphenol Content of Pearl Millet

Germination of pearl millet at 30°C for 24 hr reduced phytic acid significantly (P<0.05) which, on fermentation with mixed pure cultures of Saccharomyces diastaticus, Saccharomyces cerevisiae, Lactobacillus brevis, and Lactobacillus fermentum at 30°C for 72 hr, was eliminated or reduced to negligible levels in fermented sprouts. Concentration of polyphenols did not change on germination. The fermentation of sprouts by combinations of S. cerevisiae with L. brevis and S. cerevisiae and L. fermentum did not change polyphenol whereas S. diastaticus with L. brevis (SdLb) increased and S. diastaticus with L. fermentum combinations decreased the polyphenol in the sprouts.     

Effect of Natural Fermentation of Yams (Discorea rotundata) on Characteristics of Processed Flour

The effects of natural fermentation on chemical and physical composition of tubers (Dioscorea rotundata) for flour production were studied. A fission yeast isolated from palmwine was evaluated as inoculum for fermenting yam samples. Tubers were blanched (10 and 20 min at 70°C) before fermentation for 96 hr at 30°C. Acid production and pH changes varied with time and were influenced by availability of fermentable sugars. Fermented products, including samples inoculated with yeasts, had higher protein values. Blanching and fermentation improved color and texture, producing flours with acceptable sensory qualities after 48 hr. Fermentation offers potential for preservation and improvement in quality of yam flour.     

Evaluation of functional,antinutritional, pasting and microstructural properties of Millet flours

In the present study finger and pearl millet grains were milled and sieved to obtain flour. The flours were evaluated for chemical composition, nutritional, antinutritional, pasting and micro structural properties. Significant difference (p < 0.05) in nutrient and antinutrient contents was found among the millet flours. Protein, ash and fiber content of millet flours vary from 7.3 to 8.0 g/100 g, 2.73 to 5.16 g/100 g and 3.03 to 3.05 g/100 g. Results obtained for antinutrient factors in finger and pearl millet flours were (3.5 mg/g) and (2.2 mg/g) for tannic acid and (6.1 mg/g) and (9.2 mg/g) for phytic acid respectively. Mineral availability of pearl and finger millet flour (mg/100 g) was (109.2–139.2), (0.73–4.2), (1.18–8.7.0), (15.03–17.36) and (67.53–30.03) for calcium, zinc, iron, sodium and potassium respectively. Finger millet flour showed higher peak viscosity, breakdown, final and set back value compared to pearl millet flour. Findings from the scanning electron microscopy analysis showed microstructural differences in both millet flours. FTIR analysis showed that both finger and pearl millet flours possessed O–H and C–H compounds.     

Effect of preprocessing techniques on pearl millet flour and changes in technological properties

This study investigated the effect of some preprocessing techniques on the physicochemical and technological properties of pearl millet flour for possible industrial application. Pearl millet was processed into flour using different preprocessing techniques (blanching, debranning, fermentation and malting) and evaluated for physicochemical and functional properties, grain morphology and total viable count. The result showed that fermentation and malting brought about loosening of starch granules. Fermentation significantly reduced the bulk density by 22% and improved the colour lightness and paste viscosity properties of the preprocessed flour. Malting alone resulted in about 50% increase in protein content of the flour with improved solubility up to 64 g/100 g. Total viable count was highest in fermented sample in the order of 10⁸ cfu g^?1. Thus, the combination of fermentation and malting would give the best pearl millet flour with improved technological properties for application in the industries, thereby promoting food security in the region.     

Effect of Malting Conditions on Pearl Millet Malt Quality

The effect of malting conditions on pearl millet malt quality in two varieties, SDMV 89004 and SDMV 91018, was investigated. Grain was steeped and germinated at four temperatures, 20°, 25°, 30° and 35°C, over 5 days. Generally, malt quality parameters (percentage of roots and shoots, diastatic power (DP), α‐ and β‐amylase activity, free α‐amino nitrogen (FAN), and malting loss) were significantly affected (P < 0.001) by germination temperature and time, as well as by variety. Malt FAN and malting loss were not affected by variety. A germination temperature of 25–30°C and germination time of 3–5 days were optimal. These conditions resulted in high DP, α‐ and β‐amylase activity, good FAN and moderate malting loss. These malting conditions and the subsequent malt quality of pearl millet are similar to those reported for sorghum. Pearl millet malt can therefore be used for the production of sorghum type beers.     

Effect of Thermal Treatment on Selected Cereals and Millets Flour Doughs and Their Baking Quality

Selected cereals (rice and sorghum) and millets (finger millet and pearl millet) were steamed for 20 min at ambient pressure. The rheological properties of doughs, made from these steamed as well raw grain flours, were characterized in addition to examining their baking quality. The two-cycle compression test was employed and instrumental values were correlated with sensory attributes (color, aroma, taste, stickiness, chewiness, tearing strength, cohesiveness, and rollability) using principal component analysis (PCA). Rice doughs made from both raw as well as thermally treated flour imparted maximum hardness (96.6–99.3 N) and least cohesiveness (0.05–0.09) with highest stickiness values (105–110°) among all the dough samples at the same moisture content. Pearl millet and raw sorghum flour doughs possessed the least instrumental hardness, adhesiveness, and stickiness and were the easiest to flatten. The PCA biplot showed that sensory and instrumental cohesiveness formed a cluster on the left side on the x axis while shear force, and sensory attributes like tearing strength, chewiness, stickiness, and rollability formed another cluster on the other side of the axis. Raw rice and finger millet doughs were associated with the high extent of instrumental and sensory stickiness. Thermally treated pearl millet and sorghum doughs were the best followed by treated rice and finger millet samples to give the desirable dough characteristics, and were quite close to wheat chapathi in texture.     

Influence of storage on the protein quality of pearl millet flour

Whole grain flours of two cultivars of pearl millet (Pennisetum typhoides Rich) were stored in cans for 8 days at the prevailing room temperature (25±5°C), until the flours developed an off-flavour and bad taste. The flour samples were then evaluated for protein quality. The values of protein efficiency ratio, true digestibility, biological value, net protein retention and protein utilisation fell markedly during storage. The protein quality of the cultivar with the higher amount of oil was affected more severely.     

Effect of food processing of pearl millet (Pennisetum glaucum) IKMP‐5 on the level of phenolics,phytate, iron and zinc

Pearl millet is consumed as a staple food in semi‐arid tropical regions. With a view to upgrading the micronutrient status of pearl millet‐based foods, the effects of single operations and of porridge preparation scenarios on levels and in vitro solubility (IVS) of iron and zinc and mineral complexing factors (phytates: inositol phosphates and phenolic compounds) were tested. Disc milling of grain may add significant iron but this is not necessarily IVS iron. Soaking of grains results in a 25% loss of iron, but also facilitates endogenous phytate degradation, particularly when combined with milling and cooking. Germination and lactic acid fermentation both result in partial phytate degradation. Cooking does not decompose phytates, but results in complex formation of phenolic compounds as measured by a significant reduction in reactive hydroxyl groups. Because of its different distribution in the grain, zinc is generally less affected than iron. Phytate reduction by endogenous phytases is inhibited at low pH as caused by fermentation. Kanwa (alkaline rock salt) could be a functional cooking ingredient as a source of minerals and to react with phenolic substances. The relative IVS of iron was doubled by germination of grain and increased 3‐fold by fermentation of wholemeal slurry. Zinc IVS tended to increase on cooking with kanwa, but decreased in cooked fermented flour. Copyright © 2006 Society of Chemical Industry     

Lentil Starch Content and its Microscopical Structure as Influenced by Natural Fermentation

Lentil seeds (Lens culinaris var. vulgaris, cultivar Magda-20) were allowed to ferment naturally at different lentil flour concentrations (79 g/L, 150 g/L and 221 g/L) and temperatures (28 °C, 35 °C and 42 °C). During fermentation, samples were taken at 24 h intervals. The changes in starch content in all samples were studied. Scanning electron microscopy (SEM) was used to investigate changes in samples fermented for 96 h at two different concentrations (79 g/L and 221 g/L) and two different temperatures (28 °C and 42 °C). A considerable decrease in starch content was observed at 0 h of fermentation, defined as the time when the lentil flour was completly suspended at the established temperature. Once fermentation began, flour concentration and temperature modified starch content. Fermentation brought about a general decrease in starch content and a 32—37 % dry matter content was found in the samples after 96 h. Microscopical studies showed that endocorrosion, i.e., breakdown starting from the center of starch granules, was the main pattern observed during lentil fermentation.     

Natural fermentation of lentils Influence of time, temperature and flour concentration on the kinetics of thiamin, riboflavin and niacin

Lentils (Lens culinaris, var. vulgaris cultivar Magda-20) were naturally fermented for 96 h at different lentil flour concentrations (79, 150 and 221 g/l) and temperatures (28, 35 and 42°C). During fermentation, samples were taken at 24-h intervals and the changes in thiamin (vitamin B₁), riboflavin (vitamin B₂) and total and available niacin (vitamin B₃) were investigated. Preparation of the lentil flour suspension to be fermented (i.e. the process of mixing the flour and sterilized tap water) caused an increase of the available niacin content in all batches, while changes in thiamin and riboflavin content were related to the conditions in which the preparation of the suspensions was carried out. The whole natural fermentation process (from the raw state to after 96 h of fermentation), either did not affect or produced a slight decrease in the thiamin content of lentils. In contrast, riboflavin, available niacin and total niacin contents increased throughout the 96 h period, which ended with a 35?–?82% increase of riboflavin, a 24?–?91% increase of available niacin and a 20?–?58% increase of total niacin. The temperature during the fermentation procedure had significant effect on the levels of thiamin and riboflavin in fermented lentils. To obtain lentil flours with an improved amount of riboflavin and available niacin with a minimum loss of thiamin, the natural fermentation of lentils should be carried out for 96 h at 42°C and with a lentil flour concentration of 221 g/l.     

Evaluation of Air Oven Moisture Content Determination Procedures for Pearl Millet (Pennisetum glaucum L.)

This study evaluated moisture content determination procedures for pearl millet using seven different air oven methods. The moisture content of the pearl millet samples varied from 11–41% (wet basis). The procedures included 130°C for 1 h; 130°C for 2 h; 105°C for 5 h; 105°C for 48 h; 105°C for 72 h; 130°C for 16 h; and 130°C for 20 h. Analysis of variance revealed that at high moisture content levels above 27% (wet basis), and the mean values of the moisture content determined were not significantly different (p > 0.05). Error analysis carried out showed that the moisture content determination methods were adequate to completely remove the moisture in pearl millet with moisture less than 35% (wet basis). Regression models were developed to predict the base moisture determination method (105°C for 72 h) as a function of other procedures.