N. G. Malleshi

Health benefits of finger millet (Eleusine coracana L.) polyphenols and dietary fiber: a review

The growing public awareness of nutrition and health care research substantiates the potential of phytochemicals such as polyphenols and dietary fiber on their health beneficial properties. Hence, there is in need to identify newer sources of neutraceuticals and other natural and nutritional materials with the desirable functional characteristics. Finger millet (Eleusine coracana), one of the minor cereals, is known for several health benefits and some of the health benefits are attributed to its polyphenol and dietary fiber contents. It is an important staple food in India for people of low income groups. Nutritionally, its importance is well recognised because of its high content of calcium (0.38%), dietary fiber (18%) and phenolic compounds (0.3–3%). They are also recognized for their health beneficial effects, such as anti-diabetic, anti-tumerogenic, atherosclerogenic effects, antioxidant and antimicrobial properties. This review deals with the nature of polyphenols and dietary fiber of finger millet and their role with respect to the health benefits associated with millet.

Inhibition of aldose reductase from cataracted eye lenses by finger millet (Eleusine coracana) polyphenols.

Retinopathy is a major cause of blindness in the Western world, while cataract is one of the three major causes of blindness worldwide. Diabetes is one of the major risk factor in retinopathy and cataract. The prevalence of blindness in India is 15 per 1000 while cataract alone accounts for 80% of this blindness. Diabetes induced cataract is characterized by an accumulation of sorbitol which is mediated by the action of a key enzyme aldose reductase (AR). Non-enzymatic glycation (binding of glucose to protein molecule) induced during diabetes appear to be the key factor for AR mediated sugar-induced cataract. Finger millet polyphenols (FMP) being a major anti-diabetic and antioxidant component, we have evaluated them for AR inhibiting activity. Phenolic constituents in FMP such as gallic, protocatechuic, p-hydroxy benzoic, p-coumaric, vanillic, syringic, ferulic, trans-cinnamic acids and the quercetin inhibited cataract eye lens effectively, the latter was more potent with an IC(50) of 14.8nM. Structure function analysis revealed that phenolics with OH group at 4th position was important for aldose reductase inhibitory property. Also the presence of neighboring O-methyl group in phenolics denatured the AR activity. Finger millet seed coat polyphenols (SCP) has been found to inhibit AR reversibly by non-competitive inhibition. Results thus, provide a stronger evidence for the potentials of FMP in inhibiting cataractogenesis in humans.

Amelioration of hyperglycaemia and its associated complications by finger millet (Eleusine coracana L.) seed coat matter in streptozotocin-induced diabetic rats

Finger millet (Eleusine coracana) is extensively cultivated and consumed in India and Africa. The millet seed coat is a rich source of dietary fibre and phenolic compounds. The effect of feeding a diet containing 20% finger millet seed coat matter (SCM) was examined in streptozotocin-induced diabetic rats. Diabetic rats maintained on the millet SCM diet (diabetic experimental (DE) group) for 6 weeks exhibited a lesser degree of fasting hyperglycaemia and partial reversal of abnormalities in serum albumin, urea and creatinine compared with the diabetic control (DC) group. The DE group of rats excreted comparatively lesser amounts of glucose, protein, urea and creatinine and was accompanied by improved body weights compared with their corresponding controls. Hypercholesterolaemia and hypertriacylglycerolaemia associated with diabetes were also notably reversed in the DE group. Slit lamp examination of the eye lens revealed an immature subcapsular cataract with mild lenticular opacity in the DE group of rats compared to the mature cataract with significant lenticular opacity and corneal vascularisation in the DC group. Lower activity of lens aldose reductase, serum advanced glycation end products and blood glycosylated Hb levels were observed in the DE group. The millet SCM feeding showed pronounced ameliorating effects on kidney pathology as reflected by near normal glomerular and tubular structures and lower glomerular filtration rate compared with the shrunken glomerulus, tubular vacuolations in the DC group. Thus, the present animal study evidenced the hypoglycaemic, hypocholesterolaemic, nephroprotective and anti-cataractogenic properties of finger millet SCM, suggesting its utility as a functional ingredient in diets for diabetics.

Nutritive value of malted millet flours

The changes in proximate composition, phytate phosphorus, thiamine and ascorbic acid content of finger millet, pearl millet and foxtail millet during progressive germination were studied. Germination resulted in a slight decrease in total protein and minerals, a marked fall in phytate-phosphorus and a significant increase in the ascorbic acid content of the millets. An increase in lysine and tryptophan but no appreciable changes in threonine and sulfur amino acid content of the millets were observed as a result of germination. However, the protein efficiency ratio values of ungerminated control seeds, 48 h germinated green malt and kilned malt were not significantly different.

Quality characteristics of biscuits prepared from finger millet seed coat based composite flour

Finger millet seed coat is an edible material and contains good proportion of dietary fibre, minerals and phytochemicals. The seed coat matter (SCM) forms a by-product of millet milling, malting and decortication industries and can be utilised as composite flour in biscuit preparation. The SCM from native, malted and hydrothermally treated millet contained 9.5-12% protein, 2.6-3.7% fat and 40-48% dietary fibre, besides 3-5% polyphenols and 700-860mg/100g of calcium. The biscuits prepared using the composite flour were of crisp texture and exhibited breaking strength of 1480-1690g compared to control biscuits (1560g). The biscuits were of mild grey colour (ΔE=40-50) and exhibited higher protein, dietary fibre and calcium contents. The sensory evaluation of the biscuits indicated that 10% of SCM from native and hydrothermally processed millet and 20% from malted millet could be used in composite biscuit flour.

Glycemic response of rice, wheat and finger millet based diabetic food formulations in normoglycemic subjects

Food formulations suitable as dietary supplements to diabetic subjects based on wheat, decorticated finger millet, popped (aralu) and expanded (puri) rice each blended separately with legumes, non-fat dry milk, vegetable oils, spices and a few hypoglycemic ingredients were formulated. The formulations contained 13.0–18.3% protein, 11.3–11.8% fat, 59.9–67.5% starch and 13.2–18.0% dietary fiber. A 50-g equivalent carbohydrate portion of the foods in the form of thick porridge was provided to eight healthy adult subjects and the postprandial blood glucose response was determined. The Glycemic Index (GI) values were 55.4±9, 93.4±7, 105±6 and 109±8 for wheat-based, millet-based, aralu-based and puri-based formulations. The variations in the GI could be attributed to the nature of available as well as non-available (non-starchy polysaccharides) carbohydrates in the foods besides the processing undergone by the cereal ingredients. The higher GI of rice formulations could be due to the easily digestible nature of starches and also their lower dietary fiber contents. The study revealed the suitability of wheat-based formulation as a food supplement or as meal replacer in diabetic subjects but the unsuitability of rice-based formulations.

Physico-chemical characteristics, nutritional quality and shelf-life of pearl millet based extrusion cooked supplementary foods

The process variables for extrusion cooking of pearl millet were standardized and some of the physicochemical characteristics of the millet extrudates and also the nutritional qualities of the millet and legume-based extruded supplementary foods were determined. The millet grits less than 355 µm in size, equilibrated to 18±1% moisture content, extruded at 150±5°C temperature and at 200±10 rpm of the barrel of a twin-screw extruder yielded the extrudates of 1.75±0.21 expansion ratio and 7.5±1.5 kg breaking strength. The cold and cooked paste viscosity, the melt energy and also the carbohydrate digestibility of the extrudates indicated that the products were pre-cooked and were of ready-to-eat nature. The millet was blended with grain legumes (30%) and also with defatted soy (15%) separately and extruded to prepare ready-to-eat nutritious foods suitable as food supplements to children and mothers. The foods based on the millet and legumes and also the millet and soy contained 14.7% and 16.0% protein with 2.0 and 2.1 protein efficiency ratio values, respectively. The shelf-life of the foods was about 6 months in different flexible pouches at ambient storage conditions. The study showed that applications of extrusion cooking technology to pearl millet have promise for preparation of diversified and value-added food products from the millet.

Nutrient composition, amino acid and vitamin contents of malted sorghum, pearl millet, finger millet and their rootlets

Sorghum, pearl millet and finger millet were allowed to germinate up to 96 h and samples were withdrawn from the germinating bed at every 24 h intervals, dried at 50°C and derooted to prepare the malt. The native and the malt samples were analysed for the proximate principles, and amino acids, thiamine, riboflavin, niacin and ascorbic acid contents. Protein, fat, ash and crude fibre contents of the rootlets separated from the malt were also determined. Protein content of finger millet malt was considerably less than the native millet, but the protein, fat and mineral contents of native and malted sorghum and pearl millet were almost the same. A noticeable increase in lysine content and decrease in sulphur-containing amino acids were also recorded only in the case of finger millet on malting. Malting enhanced riboflavin, niacin and ascorbic acid contents but slightly reduced the thiamine content of sorghum as well as both the millets. The SEM photomicrographs of the endosperm portion of sorghum and pearl m...

Acceptability of supplementary foods based on popped cereals and legumes suitable for rural mothers and children

Eight types of supplementary foods based on popped cereals (wheat, ragi, bajra and sorghum) blended with legumes (soy and bengalgram) and fortified with essential vitamins and minerals were developed on a pilot plant scale. Four of the supplements were prepared with cereals, soy flour (SF) and bengal gram (BG) dhal and the other four were prepared with combinations of cereals and SF. These blends were mixed with jaggery (obtained by boiling juice out of sugarcane) syrup and pressed into compact form. One hundred gram portions of these foods provided 370 ± 20 kilocalories and 11 ± 1 g protein. Moisture, crude protein, total carbohydrates, total lipids, ash, dietary fiber and energy contents, of all the developed supplements were within the ranges prescribed by the Indian Standards Institute for processed weaning foods and could satisfactorily meet one-third of the Recommended Dietary Allowance (RDA) of these nutrients per day for preschool children. Organoleptic evaluation and feeding trials revealed that the foods were well accepted by rural mothers and children.

Physical and nutritional qualities of extruded weaning foods containing sorghum, pearl millet, or finger millet blended with mung beans and nonfat dried milk.

Sorghum, pearl millet, and finger millet flours (60% of each) were blended with toasted mung bean flour (30%) and nonfat dry milk (10%) and extruded (Brabender single screw) to make precooked, ready-to-eat, weaning foods. The extruded foods had high cold paste viscosity, but their cooked paste viscosity was lower than that of the respective blends. Chemical scores of the extruded foods were 78 for sorghum, 80 for pearl millet, and 96 for finger millet. Protein digstibility corrected amino acid scores (PD-CAS) were similar for pearl millet (68%) and finger millet (69%); PD-CAS for sorghum was 57%. Total dietary fiber content of the foods ranged from 7.6 to 10.1%, with the soluble dietary fiber content of the foods being about 10% higher than that of the corresponding blends. Extrusion enhanced the in vitro protein digestibility of foods, but no marked difference occurred in the in vitro carbohydrate digestibility among the unprocessed blends and the extruded foods. The net protein ratio, protein efficiency ratio, and biological values were higher for the finger millet food than for the pearl millet food, probably because of the higher lysine content of the finger millet protein.