Effect of gamma radiation on microbial load, physico-chemical and sensory characteristics of common spices for storage.

The effect of gamma radiation on the decontamination of microbial population, physico-chemical, radiation sensitivity and sensory characteristics of common spices for storage were evaluated. Spices were irradiated with gamma doses of 0 (as control), 2, 4, 6, 8 and 10 kGy, packed in the glass vials and stored at room temperature (22 ± 2°C) in the laboratory. In this research, Bacillus, Salmonella and Listeria species were identified in un-irradiated spice samples. Results also indicated that gamma radiation reduced the total microbial population compared to control and optimum gamma radiation doses (6 kGy for red chili and turmeric; 4 kGy for cumin, coriander, garlic and black pepper; 2 kGy for ginger powder samples) were identified for decontamination of the organisms in the studied spices. It was concluded that no significant differences before and after gamma radiation were observed in physico-chemical, nutritional and sensory properties but significantly changed in microbial load in spices samples.

Effect of dye and temperature on the physico-mechanical properties of jute/PP and jute/LLDPE based composites.

Jute fabrics and unidirectional jute fiber reinforced polypropylene (PP) and linear low density polyethylene (LLDPE) based composites were prepared successfully by compression molding technique. The unidirectional jute fiber was treated with Reactive Orange HB® and Deep Blue LW® dye to investigate physico-mechanical properties. The Reactive Orange HB® treated composites showed relatively better mechanical properties than the Deep Blue LW® treated composites. The jute fiber-based composites showed higher mechanical properties than that of jute-based fabrics. The polypropylene-based composites showed better mechanical properties than that of LLDPE. The variations of mechanical properties were also observed. The highest mechanical properties were at -18 °C and lowest at 50 °C. Water absorbent, SEM and FT-IR analysis of the composite was also carried out.

Nanocellulose-based composites and bioactive agents for food packaging.

Global environmental concern, regarding the use of petroleum-based packaging materials, is encouraging researchers and industries in the search for packaging materials from natural biopolymers. Bioactive packaging is gaining more and more interest not only due to its environment friendly nature but also due to its potential to improve food quality and safety during packaging. Some of the shortcomings of biopolymers, such as weak mechanical and barrier properties can be significantly enhanced by the use of nanomaterials such as nanocellulose (NC). The use of NC can extend the food shelf life and can also improve the food quality as they can serve as carriers of some active substances, such as antioxidants and antimicrobials. The NC fiber-based composites have great potential in the preparation of cheap, lightweight, and very strong nanocomposites for food packaging. This review highlights the potential use and application of NC fiber-based nanocomposites and also the incorporation of bioactive agents in food packaging.

Encapsulation of probiotic bacteria in biopolymeric system.

Encapsulation of probiotic bacteria is generally used to enhance the viability during processing, and also for the target delivery in gastrointestinal tract. Probiotics are used with the fermented dairy products, pharmaceutical products, and health supplements. They play a great role in maintaining human health. The survival of these bacteria in the human gastrointestinal system is questionable. In order to protect the viability of the probiotic bacteria, several types of biopolymers such as alginate, chitosan, gelatin, whey protein isolate, cellulose derivatives are used for encapsulation and several methods of encapsulation such as spray drying, extrusion, emulsion have been reported. This review focuses on the method of encapsulation and the use of different biopolymeric system for encapsulation of probiotics.

Mechanical and barrier properties of nanocrystalline cellulose reinforced chitosan based nanocomposite films.

Nanocrystalline cellulose (NCC) reinforced chitosan-based biodegradable films were prepared by solution casting. The NCC content in the films was varied from 1 to 10% (dry wt. basis). It was found that the tensile strength (TS) of the nanocomposite films with 5% (w/w) NCC content was optimum with an improvement of 26% compared to the control chitosan films. Incorporation of NCC also significantly improved barrier properties. Water vapor permeability (WVP) of the chitosan/NCC films was decreased by 27% for the optimum 5% (w/w) NCC content. Swelling studies revealed a decrease in water uptake of the NCC-reinforced chitosan films. Analyses of thermal properties showed no significant effect of NCC whereas X-ray diffraction studies confirmed the appearance of crystalline peaks in the nanocomposite films. Surface morphology of the films was investigated by scanning electron microscopy and it was found that NCC was dispersed homogenously into chitosan matrix.

Nanocrystalline cellulose (NCC) reinforced alginate based biodegradable nanocomposite film.

Nanocrystalline cellulose (NCC) reinforced alginate-based nanocomposite film was prepared by solution casting. The NCC content in the matrix was varied from 1 to 8% ((w/w) % dry matrix). It was found that the nanocomposite reinforced with 5 wt% NCC content exhibits the highest tensile strength which was increased by 37% compared to the control. Incorporation of NCC also significantly improved water vapor permeability (WVP) of the nanocomposite showing a 31% decrease due to 5 wt% NCC loading. Molecular interactions between alginate and NCC were supported by Fourier Transform Infrared Spectroscopy. The X-ray diffraction studies also confirmed the appearance of crystalline peaks due to the presence of NCC inside the films. Thermal stability of alginate-based nanocomposite films was improved after incorporation of NCC.

Modification and characterization of biodegradable methylcellulose films with trimethylolpropane trimethacrylate (TMPTMA) by γ radiation: effect of nanocrystalline cellulose.

Methylcellulose (MC)-based films were prepared by solution casting from its 1% aqueous suspension containing 0.25% glycerol. Trimethylolpropane trimethacrylate (TMPTMA) monomer (0.1-2% by wt) along with the glycerol was added to the MC suspension. The films were cast and irradiated from a radiation dose varied from 0.1 to 10 kGy. Then the mechanical properties such as tensile strength (TS), tensile modulus (TM), and elongation at break (Eb) and barrier properties of the films were evaluated. The highest TS (47.88 PMa) and TM (1791.50 MPa) of the films were found by using 0.1% monomer at 5 kGy dose. The lowest water vapor permeability (WVP) of the films was found to be 5.57 g·mm/m(2)·day·kPa (at 0.1% monomer and 5 kGy dose), which is 12.14% lower than control MC-based films. Molecular interactions due to incorporation of TMPTMA were supported by FTIR spectroscopy. A band at 1720 cm(-1) was observed due to the addition of TMPTMA in MC-based films, which indicated the typical (C═O) carbonyl stretching. For the further improvement of the mechanical and barrier properties of the film, 0.025-1% nanocrystalline cellulose (NCC) was added to the MC-based suspension containing 1% TMPTMA. Addition of NCC led to a significant improvement in the mechanical and barrier properties. The novelty of this investigation was to graft insoluble monomer using γ radiation with MC-based films and use of biodegradable NCC as the reinforcing agent.

Physico-mechanical properties of wound dressing material and its biomedical application.

A bioadhesive wound dressing material, based on gelatin, was prepared by solution casting, and its properties were evaluated. The tensile strength (TS) and percentage elongation at break (Eb) of the membranes were found to be 12.7 MPa and 40.4%, respectively. The buffer uptake and water uptake of the prepared membranes were found to be 298 and 312%, respectively, after 8 min. A scanning electron micrograph of the membrane revealed its uniform porosity, which is an essential criterion to be an ideal wound dressing. From microbial sensitivity analysis, it was found that the membrane had a significant resistance against infection. The wound-healing characteristics of the membrane were evaluated using a rat (Rattus norvegicus) model. Full-thickness wounds were created on the ventral side of the Rattus norvegicus and were dressed with the membrane; eco-plast was used as a control. The wound healing and bioadhesion were monitored at 3-day intervals by real-time imaging. The results revealed that the prepared membrane was more effective in healing the wound than conventional wound dressing.

Production and properties of nanocellulose-reinforced methylcellulose-based biodegradable films.

Methylcellulose (MC)-based films were prepared by casting from its 1% aqueous solution containing 0.5% vegetable oil, 0.25% glycerol, and 0.025% Tween 80. Puncture strength (PS), puncture deformation (PD), viscoelasticity coefficient, and water vapor permeability (WVP) were found to be 147 N/mm, 3.46 mm, 41%, and 6.34 g.mm/m(2).day.kPa, respectively. Aqueous nanocellulose (NC) solution (0.1-1%) was incorporated into the MC-based formulation, and it was found that PS was improved (117%) and WVP was decreased (26%) significantly. Films containing 0.25% NC were found to be the optimum. Then films were exposed to gamma radiation (0.5-50 kGy), and it was revealed that mechanical properties of the films were slightly decreased after irradiation, whereas barrier properties were further improved with a decrease of WVP to 28.8% at 50 kGy. Molecular interactions due to incorporation of NC were supported by FTIR spectroscopy. Thermal properties of the NC-containing films were improved, confirmed by TGA and DSC. Crystalline peaks appeared due to NC addition, found by XRD. Micrographs of films containing NC were investigated by SEM.