T.S. Chandra

Changes in carbohydrate, free amino acids, organic acids, phytate and HCl extractability of minerals during germination and fermentation of finger millet (Eleusine coracana)

Finger millet (Eleusine coracana) also known as ‘ragi’ in India is a source of carbohydrate, protein and mineral that is comparable to other common cereal grains. However, antinutrients like phytate and tannins reduce the nutrient bioavailability which can be improved by suitable processing methods such as germination and fermentation. In our study, the finger millet was germinated (24 h) and then subjected to fermentation (48 h). Major biochemical changes occurred during fermentation (6–18 h) compared to germination (24 h). The processing decreased the pH from 5.8 to 3.8 and increased the total sugars (2-fold), reducing sugars (13-fold) and free amino acids (10-fold). Lactic acid was the predominant organic acid (3.7%). The phytate content decreased by 60% with an increase in HCl-extractable minerals of 47%. The phytate × Ca/Zn molar ratio decreased from 163 to 66.2, indicative of an increased Zn bioavailability. In conclusion, a combination of germination and fermentation is a potential process for decreasing the antinutrient levels and enhancing digestibility.

Statistical optimization of medium components for enhanced riboflavin production by a UV-mutant of Eremothecium ashbyii

Abstract The nutritional requirements for riboflavin production by a UV-mutant of Eremothecium ashbyii UV-18-57 were optimized using indigenous agroindustrial by-products. The medium components considered include molasses as carbon source, sesame seed cake (SSC) as nitrogen source, yeast extract, KH 2 PO 4 , NaCl, MgSO 4 7H 2 O and Tween-80 in shake flask experiments. Initial screening using a Plackett–Burman statistical design identified four components, i.e., molasses, SSC, KH 2 PO 4 and MgSO 4 7H 2 0 as significantly, influencing riboflavin production (confidence levels above 80%). Response surface methodology was applied to determine the mutual interactions between these four components and optimal levels for riboflavin production. The optimal concentrations for enhanced production of riboflavin were: (g/1) molasses=30.85; SSC=39.80; KH 2 PO 4 =1.484 and MgSO 4 7H 2 O=0.072.

Do earthworms affect dynamics of functional response and genetic structure of microbial community in a lab-scale composting system?

Two laboratory-scale systems were set up (i) composting (without earthworms) and (ii) vermicomposting (with earthworms) and were monitored for 60 days after pre-composting. The physico-chemical parameters (pH, C/N, organic matter, NH(4)(+)-N and ash content) showed similar evolution in both systems except a higher NH(4)(+)-N in the initial vermicomposts. However, principle component analysis (PCA) of enzymatic activities and community level physiological profiles revealed differences in the functional response of microbial communities in compost and vermicompost during maturation. Dehydrogenase activity and bacterial counts indicated a steady decrease in biological activity and population during composting, whereas vermicomposting exhibited higher activity on day 30 and a reduction in bacterial counts on day 10. PCA of denatured gradient gel electrophoresis (DGGE) profiles showed divergent dynamics of bacterial communities in two processes. These results indicated differences in the functional response and genetic structure of microbial community in composts and vermicomposts despite similar changes in their physico-chemical parameters.

ESR spectroscopic studies on free radical quenching action of finger millet (Eleusine coracana)

Abstract The free radical quenching action of finger millet (Eleusine coracana) on 1,1′-diphenyl-2-picrylhydrazyl (5.407×1017 spins/ml−1) and hydroxyl (0.6015×1015 spins /ml−1) radicals was studied by electron spin resonance (ESR) spectrometry. A 10 ml concentrate of the methanol extract was prepared using 25 g of the cereal grains and all analysis done after 1:10 dilution. DPPH radical quenching with 50 μl of the extracts showed that the brown finger millet quenched 94% whereas the white finger millet quenched only 4%. The phenolic content of brown finger millet was 96% higher than the white variety. Processing of the brown finger millet by germination and/or fermentation decreased the quenching activity. In comparison, foxtail millet, pearl millet and sorghum, quenched 91, 59 and 52 percent respectively, while wheat, rice (dehusked) and rice husk quenched 18, 1.8 and 20% respectively. Brown finger millet (50 μl) also quenched 77% of hydroxyl radicals. The results indicate that finger millet is a potent source of antioxidant compounds.

Production and potential applications of a xylanase from a new strain of Streptomyces cuspidosporus.

Enzyme production by a new mesophilic Streptomyces isolate was investigated which grew optimally on 1% (w/v) xylan and 10% (w/v) wheat bran at pH 7 and 37 °C. Xylan induced only CMCase (0.29 U/ml) besides xylanase (22–35 U/ml, 40–49 U/mg protein). Wheat bran induced xylanase (105 U/ml, 17.5 U/mg protein), CMCase (0.74 U/ml), β-xylosidase (0.009 U/ml), β-glucosidase (0.026 U/ml), α-L-arabinofuranosidase (0.049 U/ml), amylase (1.6 U/ml) and phytase (0.432 U/ml). The isolate was amenable to solid state cultivation and produced increased levels of xylanase (146 U/ml, 28 U/mg protein). The pH and temperature optima of the crude xylanase activity were 5.5 and 65 °C respectively. The pI was 6.0 as determined by PEG precipitation. The crude enzyme was applied in treatment of paper pulp and predigestion of poultry feed and was found to be effective in releasing sugars from both and soluble phosphorus from the latter.

The effect of fermentation on the primary nutrients in foxtail millet (Setaria italica)

Foxtail millet (Setaria italica), consumed by the rural and tribal populations in South India, is a rich source of nutrients. Fermentation by endogenous microflora increased the total soluble sugars and reducing sugars with a simultaneous decrease in the starch content. The protein extractability and albumin/globulin fractions were improved. The beneficial long-chain fatty acid profile of raw flour was retained. Acetic and butyric acid were the major short-chain fatty acids produced. Most of these changes occurred in the first 24 h of fermentation.

Inhibition of collagen glycation and crosslinking in vitro by methanolic extracts of Finger millet (Eleusine coracana) and Kodo millet (Paspalum scrobiculatum).

The present investigation was carried out to study the effects of methanolic extracts of Finger millet (Eleusine coracana) and Kodo millet (Paspalum scrobiculatum) on glycation and crosslinking of collagen. Tail tendons obtained from rats weighing 200-225 g were incubated with glucose (50 mM) and 3 mg of extracts of the above millets in methanol under physiological conditions of temperature and pH for 10 days. Early glycation was estimated by phenol-sulfuric acid method and the crosslinking was assessed by pepsin digestion, cyanogen bromide peptide map and viscosity measurements. Tendon collagen incubated with glucose (50 mM) showed 65% solubility on pepsin treatment; poor resolution of bands in the cyanogen bromide peptide map, and intrinsic viscosity of 0.84 dl/g. The collagen incubated with Finger millet and Kodo millet extracts inhibited glycation; 89% and 92% solubility in pepsin; good resolution of bands in the cyanogen bromide peptide map and intrinsic viscosity of 0.46 and 0.58 dl/g respectively. The study implicates the potential usefulness of the above millets in protection against glycation and crosslinking of collagen.

Microbial population and biochemical changes in fermenting finger millet (Eleusine coracana)

Natural fermentation of finger millet (Eleusine coracana) was carried out for 48 h. Microbiological and chemical analysis was performed throughout the fermentation process. The fermentation was heterolactic dominated by lactic acid bacteria accompanied by the production of lactic and acetic acids with decrease in pH and increase in titratable acidity. The microbial population increased until 18 to 24 h accompanied by a rapid decrease in total and reducing sugars. The microflora stabilized between 24 and 48 h, during which time the total and α-amylase activities increased with accumulation of sugars. Total free amino acids also increased. Yeast counts were low and moulds and coliforms were absent. Repeated fermentations showed consistency in the qualitative and quantitative changes in microflora. Five predominant types of bacteria, strains belonging to Leuconostoc, Pediococcus and Lactobacillus were identified. Of these only one type, Pediococcus, dominated (>80%) in the latter half of fermentation.

Isolation and characterization of some new oxalate-decomposing bacteria

Forty-one cultures degrading and assimilating oxalate were isolated from chicken dung. Characterization indicated six different types. One of these belonged to the genusAlcaligenes hitherto never reported to degrade oxalate. Three groups ofPseudomonas strains differed physiologically from strains already known.

Structural divergence of bacterial communities from functionally similar laboratory‐scale vermicomposts assessed by PCR‐CE‐SSCP

Aims:  To evaluate bacterial community structure and dynamics in triplicate vermicomposts made from the same start‐up material, along with certain physico‐chemical changes.