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George J.,Defence Food Research Laboratory
Carbohydrate Polymers | Year: 2012

Bacterial cellulose obtained from Gluconacetobacter xylinus in the form of long fibers were acid hydrolyzed under controlled conditions to obtain cellulose nanocrystals. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) confirmed the formation of rod like cellulose nanocrystals having an average diameter and length of 20 ± 5 nm and 290 ± 130 nm respectively. These nanocrystals were used to prepare gelatin nanocomposite films and characterized for elucidating its performance. The formation of percolated networks of cellulose nanocrystals within gelatin matrix resulted in improving the mechanical properties of nanocomposites. The moisture sorption and water vapor permeability (WVP) studies revealed that the addition of cellulose nanocrystals reduced the moisture affinity of gelatin, which is very favorable for edible packaging applications. Results of this study demonstrated the use of bacterial cellulose nanocrystals (BCNCs) in the fabrication of edible, biodegradable and high-performance nanocomposite films for food packaging applications at relatively low cost. © 2011 Elsevier Ltd. All rights reserved.

Shiby V.K.,Defence Food Research Laboratory | Mishra H.N.,Indian Institute of Technology Kharagpur
Critical Reviews in Food Science and Nutrition | Year: 2013

Fermented foods and beverages possess various nutritional and therapeutic properties. Lactic acid bacteria (LAB) play a major role in determining the positive health effects of fermented milks and related products. The L. acidophilus and Bifidobacteria spp are known for their use in probiotic dairy foods. Cultured products sold with any claim of health benefits should meet the criteria of suggested minimum number of more than 106 cfu/g at the time of consumption. Yoghurt is redefined as a probiotic carrier food. Several food powders like yoghurt powder and curd (dahi) powder are manufactured taking into consideration the number of organisms surviving in the product after drying. Such foods, beverages and powders are highly acceptable to consumers because of their flavor and aroma and high nutritive value. Antitumor activity is associated with the cell wall of starter bacteria and so the activity remains even after drying. Other health benefits of fermented milks include prevention of gastrointestinal infections, reduction of serum cholesterol levels and antimutagenic activity. The fermented products are recommended for consumption by lactose intolerant individuals and patients suffering from atherosclerosis. The formulation of fermented dietetic preparations and special products is an expanding research area. The health benefits, the technology of production of fermented milks and the kinetics of lactic acid fermentation in dairy products are reviewed here. © 2013 Copyright Taylor and Francis Group, LLC.

Pal A.,Defence Food Research Laboratory | Khanum F.,Defence Food Research Laboratory
Process Biochemistry | Year: 2011

Response surface methodology was used for process optimization to covalently immobilize xylanase on the surface of glutaraldehyde-alginate beads. The process, optimized with respect to minimum 'enzyme load', had an efficiency of >91%. An increase in Km (from 0.9 to 1.49%), Vmax (from 7092 to 8000 IU/ml), optimum pH (from 5 to 5.5) and temperature (from 40 to 45°C) was recorded after immobilization. An improvement in thermostability of immobilized xylanase, judged by increased half-lives and D-values, was also observed. Thermodynamically, the better stability of immobilized xylanase could be attributed to the increase in enthalpy (ΔH°) and free energy (ΔG°) change after covalent attachment. The enzyme could be reused 5 times while retaining >85% of its original activity. The method of immobilization can overcome the problem of reduced permeability of xylan, a high molecular weight substrate, to its enzyme which is conventionally entrapped within the alginate beads. © 2011 Elsevier Ltd. All rights reserved.

Kumar K.H.,Defence Food Research Laboratory | Khanum F.,Defence Food Research Laboratory
Cellular and Molecular Neurobiology | Year: 2013

Hydrogen peroxide (H2O2), a major reactive oxygen species produced during oxidative stress, has been implicated in the pathophysiology of various neurodegenerative conditions. Cyperus rotundus is a traditional medicinal herb that has recently found applications in food and confectionary industries. In the current study, the neuroprotective effects of Cyperus rotundus rhizome extract (CRE) through its antioxidant and anti-apoptotic machinery to attenuate H2O2-induced cell damage on human neuroblastoma SH-SY5Y cells have been explored. The results obtained demonstrate that pretreatment of cells with CRE for 2 h before administration of H2O2 for 24 h ameliorates the cytotoxicity induced by H2O2 as evidenced by MTT and LDH assays. CRE exhibited potent antioxidant activity by regulating the enzymes/proteins levels such as SOD, CAT, GPx, GR, HSP-70, Caspase-3, and Bcl-2. The pretreatment restored H2O2-induced cellular, nuclear, and mitochondrial morphologies as well as increased the expression of Brain derived nerve growth factor (BDNF). The anti-oxidant and anti-apoptotic potentials of the plant extract may account for its high content of phenolics, flavonoids, and other active principles. Taken together, our findings suggest that CRE might be developed as an agent for neurodegeneration prevention or therapy. © 2012 Springer Science+Business Media, LLC.

Pal A.,Defence Food Research Laboratory | Khanum F.,Defence Food Research Laboratory
Process Biochemistry | Year: 2011

An extracellular xylanase was purified from Aspergillus niger DFR-5 up to absolute homogeneity using (NH4)2SO4 fractionation (30-65%), size exclusion (Sephadex G-100) and ion-exchange (DEAE-cellulose) chromatography. The preparation yielded a single peak in RP-HPLC confirming its purity. Molecular mass of xylanase as revealed by gel filtration and SDS-PAGE was ∼32 kDa confirming its monomeric nature. Various kinetic parameters of xylanase towards thermo-inactivation were calculated. ΔH°, ΔS° and ΔG° of thermal denaturation suggested that enzyme undergoes significant processes of aggregation instead of unfolding during denaturation. A central composite rotatable design was used to study the interactive effects of temperature, pH and time on xylanase stability which revealed the existence of significant interactions between them. A regression equation was developed to deduce the residual activity of xylanase under any conditions of experimental parameters within the domain. The findings will be useful while applying the enzyme in different juice clarification where pH varies considerably. © 2010 Elsevier Ltd.

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