Evaluation of antioxidant and antimicrobial properties of finger millet polyphenols (Eleusine coracana)

Phenolic acids from finger millet (Eleusine coracana) milled fractions (whole flour, seed coat, 3%, 5% and 7%) were isolated and their antioxidant and antimicrobial properties were evaluated. Acidic methanol extracts from seed coat to whole flour were rich in polyphenol content and were found to be stable up to 48 h at pH 4, 7, and 9 as studied by ultraviolet spectroscopy. Diadzene, gallic, coumaric, syringic and vanillic acids were identified as major phenolic acids from the extracted phenolics. Diadzene content was highest in concentration in the 5% flour. The reducing power of seed coat extract was significantly (p < 0.05) higher than that of whole flour extract. Antioxidant activity (AA) as determined by the p-carotene-linoleic acid assay indicated that the AA was highest in seed coat extract (86%), whilst at the same concentration it was only 27% in the whole flour extract. The seed coat extract showed higher antimicrobial activity against Bacillus cereus and Aspergillus flavus compared to whole flour extract. From these observations, it can be inferred that the polyphenols are responsible for the microbial activity of the millet and the results indicate that potential exists to utilise finger millet seed coat as an alternative natural antioxidant and food preservative. (C) 2008 Elsevier Ltd. All rights reserved

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

Influence of seed mycoflora and harvesting conditions on milling, popping and malting qualities of sorghum (Sorghum bicolor)

Four cultivars of sorghum were artificially inoculated with Fusarium moniliforme conidia at flowering and bagged. These samples along with their untreated controls were harvested at physiological maturity and 2 weeks after physiological maturity. The grains obtained from both the treatments were studied for their milling, malting and popping characteristics. Grains harvested at physiological maturity stage possessed superior milling and malting characteristics whereas late-harvested grains exhibited better popping characteristics. Milling and popping reduced the seed mycoflora considerably

The effect of cooking on the nano-sized crystallites in finger millet and barley using waxs data

Finger millet and barley malt flours, as well as their blends, were cooked and the hydrolysates were spray dried. These samples along with native millet and barley flours were used for recording X-ray diffraction data in the range 2θ  =  2 to 40°. Using an in-house line profile analysis (LPA) program based on the Fourier method, the nano-sized crystallite dimension along with the intrinsic strain present in these cereals have been estimated for the first time. The effects of hydrolyzing the malts and their blends on the nano-sized crystallites have been discussed

Nutritional and sensory profile of two Indian rice varieties with different degrees of polishing

Traditional hand-pounded rice has been replaced today with highly polished white rice in the Asian Indian diets. The study aimed to evaluate the nutritional as well as the sensory differences between the brown (0% polish) and the rice milled to different degrees of polish (2.3, 4.4 and 8.0%). Bapatla and Uma (red pigmented) varieties in both raw and parboiled forms were used. The protein, fat, dietary fibre, γ-oryzanol, polyphenols, vitamin E, total antioxidant activity and free radical scavenging abilities of the brown rice decreased while the available carbohydrates increased with polishing. Sensory attributes of the cooked rice samples (whiteness, grain intactness, fluffiness, firmness, stickiness, chewiness and the cooked rice aroma) were evaluated by trained panelists. Scores for branny taste and chewiness decreased with polishing. On the whole, brown rice of both the varieties was readily accepted by the well-informed sensory trained panelists

Glycaemic index of three Indian rice varieties

Three commonly consumed Indian rice varieties (Sona Masuri, Ponni and Surti Kolam) were tested for their glycaemic index (GI). Healthy volunteers were recruited and after an overnight fast were given a 50 g available carbohydrate portion of glucose (reference food) or different varieties of cooked rice (test foods) on separate occasions. The fasting as well as postprandial capillary blood glucose response was determined over 2 h, and the incremental area under the curve (IAUC) was calculated. The GI was calculated as the IAUC of the test food/IAUC of the reference food (glucose) × 100. The differences between the GI values for Sona Masuri (72.0 ± 4.5), Ponni (70.2 ± 3.6) and Surti Kolam (77.0 ± 4.0) rice varieties were non-significant (p = 0.606) and are all classified as high GI varieties of rice. There is an urgent need to study the GI of other commonly consumed rice varieties and to develop rice of a lower GI value

Effect of gamma irradiation on the 24-h glycemic responses of parboiled brown rice diets in Asian Indian adults: A randomized cross-over study

Background: The nutritional importance of brown rice (BR) is well established. Despite several nutritional benefits of BR, its consumption remains limited due to long cooking time and limited shelf-life. BR can be subjected to processing to improve shelf-life. Gamma irradiation is one such strategy, but it could induce changes in the grain and thus affect its glycemic properties. Aims and objectives: The aim of this study was to look at the 24-h glycemic response of irradiated and non-irradiated BR-based iso-caloric diets in Asian Indians. Methods: Fifteen (mean body mass index: 24 ± 2.6 kg/m2) Asian Indian adults without diabetes, aged 25–39 years, participated in this randomized cross-over study. Iso-caloric diets were prepared with two varieties (ADT 43 and Swarna) of parboiled gamma-irradiated brown rice with 750–820 Gy dosage (IBR) and non-irradiated brown rice (NIBR). After the participants consumed these diets, 24-h glycemic responses were recorded using a continuous glucose monitoring system. The mean positive change from baseline glucose concentration was calculated as the incremental area under the curve (IAUC) for both the diets. Results: The percentage difference in 24-h average IAUC was 10% lower in the IBR diets when compared with NIBR diets, irrespective of the variety of BR (P = 0.56). In the case of ADT 43 rice variety, both IBR and NIBR diets showed similar IAUC (P = 0.68). However, the IBR of Swarna rice variety showed 21% lower IAUC when compared with the NIBR diet (P = 0.21). Comparing the IBR varieties, Swarna showed 21% lower IAUC than ADT 43 (P = 0.21), whereas between NIBR varieties, only 0.79% difference was observed between ADT 43 and Swarna (P = 0.93). Conclusions: Gamma irradiation of parboiled BR did not produce significant differences in the 24-h glycemic responses for BR-based diets. Swarna variety was better than ADT 43 with regard to glycemic response. Judicious application of radiation technology to BR varieties may help in shelf-life extension without affecting the glycemic properties