Production,thermal stability and immobilisation of inulinase from Fmarium oxysporum

Fusarium oxysporum produced maximum extracellular inulinase after 9 days of its growth at 25°C on a medium (pH 5.5) containing 3% fructan and 0.2% sodium nitrate. The level of this enzyme decreased on the addition of either glucose, fructose, galactose or sucrose to F. oxysporum already growing on a fructan-containing medium. A significant increase in invertase production which resulted in an increase of the invertase/inulinase (S/I) ratio, was observed on addition of inulin to this fungus growing on other carbon sources. Glycerol (10%) gave better protection to inulinase against thermal denaturation at 50°C compared to ethylene glycol and sorbitol. Inulinase immobilised in polyacrylamide gel retained 45% of its original activity. The immobilised enzyme showed a higher optimum temperature (45°C) compared to free enzyme (37°C). The immobilised enzyme after storage at 25°C for 96 h showed 58% activity. Thermal stability of entrapped inulinase increased in the presence of inulin.     

Anti-oxidant activity and total phenolic content of some Asian vegetables

The anti-oxidant activity of extracts from 36 vegetables was evaluated by using a model system consisting of β-carotene and linoleic acid. The total phenolics of the extracts was determined spectrophotometrically according to the Folin–Ciocalteau procedure and ranged from 34 to 400 mg (100 g)⁻¹ on a fresh weight basis. Mint, aonla, black carrots, chenopodium, fenugreek, kachnar and ginger had high phenolic contents. The anti-oxidant activity expressed as per percent inhibition of oxidation ranged from a high of 92% in turmeric extracts to a low of 12.8% in long melon. Other vegetables found to have high anti-oxidant activity (>70%) were kachnar, aonla, ginger, fenugreek, mint, beetroot, black carrots, Brussels sprouts, broccoli, lotus stem, yam, coriander and tomato. Anti-oxidant activity correlated significantly and positively with total phenolics ( r ²=0.6578, P  < 0.05). The results indicate that vegetables containing high phenolics may provide a source of dietary anti-oxidants.     

Influence of samarium doping on the phase stability and optical properties of calcium silicates derived from agro-food wastes

Calcium silicates are very stable and good hosts for luminescent materials. These calcium silicates are synthesized using cost-effective agro-food wastes such as rice husk ash and eggshell powder along with doping of samarium oxide [Ca_3?xSi₂O₇:xSm³⁺(x(%)?=?0.25, 0.50, 0.75, and 1.00)] via solid-state reaction method. X-ray diffraction confirms that the Ca₃Si₂O₇ phase co-exists with the monoclinic-Ca₂SiO₄ phase. An increase in doping concentration of Sm³⁺ enhances the Ca₂SiO₄ phase content. Two types of morphology can be seen in the SEM micrographs confirming the presence of two phases. Photoluminescence emission spectra contain peaks in the visible region. Characteristic emission peaks of Sm³⁺ are present along with strong peaks due to the titanium ions present in agro-food wastes. Commission International de'Eclairage (CIE) co-ordinates correspond to the green region, which is significantly different from the CIE co-ordinates of Sm³⁺ doped samples derived from mineral oxides. This study presents an alternate use of agro-food wastes for synthesizing visible light-emitting phosphors and presents a mechanism for stabilizing Ca₂SiO₄ in waste-derived samples.