Even minimal polishing of an Indian parboiled brown rice variety leads to increased glycemic responses.

BACKGROUND AND OBJECTIVES: To evaluate the effect of polishing on the glycemic properties of Indian parboiled brown rice. METHODS AND STUDY DESIGN: We evaluated the effect of different degrees of polishing on the glycemic and insulinemic responses of Bapatla (BPT-5204), Indian parboiled Indica rice variety. Brown rice (BR), under milled rice (UMR) and white rice (WR) with 2.3% and 9.7% degree of polishing (DOP), respectively, were prepared and evaluated for the glycemic properties. Incremental Area Under the Curves (IAUC) were estimated for both glycemic index (GI) in 12 healthy participants (6 men, 6 women) and 24 hr glycemic response studies in 13 overweight participants (5 men, 8 women) using continuous glucose monitoring (CGM) system with ≈2000 kcal/day rice diets. Differences in pre and post meal insulin (Δ) were assessed. RESULTS: The GI of WR (GI=79.6) and UMR (GI=73) were significantly higher than BR (GI=57.6) (p<0.01). Similar results were obtained for 24 hr glycemic responses [IAUC: WR=58.4, UMR=55.5, BR=34.7 mg*5 min/dL, respectively]. The Δ Insulin responses were lower with BR meals compared with UMR and WR (p=0.025; p=0.003). CONCLUSIONS: Both UMR and WR had a high GI while BR had a medium GI. This could have influenced the 24 h glycaemic and insulinemic responses of BR which had the lowest responses as compared with UMR and WR, and the latter two had similar higher responses. Thus any degree of polishing leads to higher glycaemic responses.

Influence of hydrothermal processing on functional properties and grain morphology of finger millet.

Finger millet was hydrothermally processed followed by decortication. Changes in color, diameter, density, sphericity, thermal and textural characteristics and also some of the functional properties of the millet along with the grain morphology of the kernels after hydrothermal processing and decortication were studied. It was observed that, the millet turned dark after hydrothermal processing and color improved over native millet after decortication. A slight decrease in grain diameter was observed but sphericity of the grains increased on decortication. The soft and fragile endosperm turned into a hard texture and grain hardness increased by about 6 fold. Hydrothermal processing increased solubility and swelling power of the millet at ambient temperature. Pasting profile indicated that, peak viscosity decreased significantly on hydrothermal processing and both hydrothermally processed and decorticated millet exhibited zero breakdown viscosity. Enthalpy was negative for hydrothermally processed millet and positive for decorticated grains. Microscopic studies revealed that the orderly structure of endosperm changed to a coherent mass after hydrothermal processing and the different layers of seed coat get fused with the endosperm.

Effect of processing on the microstructure of finger millet by X-ray diffraction and scanning electron microscopy.

Finger millet is one of the important minor cereals, and carbohydrates form its major chemical constituent. Recently, the millet is processed to prepare hydrothermally treated (HM), decorticated (DM), expanded (EM) and popped (PM) products. The present research aims to study the changes in the microstructure of carbohydrates using X-ray diffraction and scanning electron microscopy. Processing the millet brought in significant changes in the carbohydrates. The native millet exhibited A-type pattern of X-ray diffraction with major peaks at 2θ values of 15.3, 17.86 and 23.15°, whereas, all other products showed V-type pattern with single major peak at 2θ values ranging from 19.39 to 19.81°. The corresponding lattice spacing and the number of unit cells in a particular direction of reflection also reduced revealing that crystallinity of starch has been decreased depending upon the processing conditions. Scanning electron microscopic studies also revealed that the orderly pattern of starch granules changed into a coherent mass due to hydrothermal treatment, while high temperature short time treatment rendered a honey-comb like structure to the product. However, the total carbohydrates and non-starch polysaccharide contents almost remained the same in all the products except for DM and EM, but the individual carbohydrate components changed significantly depending on the type of processing.

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.

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.

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.

Chemical composition of garden cress (Lepidium sativum) seeds and its fractions and use of bran as a functional ingredient.

Garden cress (Lepidium sativum) belonging to the family Cruciferae grown in India, Europe and US is an underutilized crop. The edible whole seed is known to have health promoting properties. Hence, it was assumed that these seeds can be a functional food. A preliminary work on chemical composition of seeds was carried out and the possibility of using it as nutraceutical food ingredient in dietary fiber formulation was explored. Three fractions namely whole meal (WM), endosperm and bran were analyzed for chemical composition. The yield of the endosperm and the bran fraction were 72 and 28%, respectively. The WM, endosperm and bran had 22.5, 27.7 and 12.6% protein, 27.5, 33.1 and 6% fat, 30, 13.6 and 75% dietary fibre (DF), and 1193.00, 945.15 and 1934.57 mg% potassium respectively. The major protein on SDS-PAGE was of 29.5 kDa. The most abundant amino acid was glutamic acid (19.3%) and the essential amino acid, leucine was the highest (8.21 +/- 0.01%) and methionine the lowest (0.97 +/- 0.02%). The major fatty acid was linolenic acid (30.2%) and low amount of erucic acid (3.9%) was also present. Bran having high water holding capacity and high DF, its use as source of DF was explored. The product contained 12% protein, 4% fat and 74.3% DF and exhibited desirable functional properties such as dispersibility, gelling ability, stability, formed homogenous mild alkaline suspension and was comparable to proprietary DF.