Sankar Chandra Deka

Isolation and characterization of cellulose nanofibers from culinary banana peel using high-intensity ultrasonication combined with chemical treatment.

In the present study, culinary banana peel was explored as a source of raw material for production of cellulose nanofibers (CNFs). For isolation of CNFs, first the peel flour was subjected to different chemical treatments to eliminate non-cellulosic compounds. The obtained chemically treated cellulose fibers were then mechanically tailored and separated into nanofibers using high-intensity ultrasonication at different output power ranging from 0 to 1000 W. The presences of nanofibers in all samples were confirmed by TEM. Increasing output power of ultrasonication reduced size of CNFs and generated more thinner and needle-like structure. SEM, FT-IR and XRD results indicated chemical treatment employed was effective in removing compounds other than cellulose fibers. Thermal analyses evinced the developed CNFs enhanced thermal properties which serve the purpose as an effective reinforcing material to be used as bionanocomposites. Hence, the production of CNFs from this underutilized agro-waste has potential application in commercial field that can add high value to culinary banana.

Baking loss of bread with special emphasis on increasing water holding capacity.

Potato flour (PF), hydroxypropyl methylcellulose (HPMC) and honey were used as baking agents and their effects on baking loss and sensory quality were studied. PF at 1, 2 and 4% levels decreased baking loss followed by HPMC and honey. Water absorption was substantially high with the HPMC (70.8–80.8%) and PF (61.7–71.7%) compared to honey and normal standard bread. PF incorporation increased shelf-life (6–7 days) as compared to HPMC and honey. HPMC incorporated bread had higher moisture content (36.8–38.0%) followed by PF (34.5–35.8%) and honey (34.7%). The ash content was in the order of PF (1%) > honey (4%) > PF (2%) > normal bread > HPMC (0.5 g) > PF (4%) > HPMC (1 g) > HPMC (1.5 g). PF incorporated bread had sensorily highest acceptance followed by HPMC and honey.

Antimicrobial and enzymatic antibrowning film used as coating for bamboo shoot quality improvement.

Edible films were prepared with varying proportion of alginate and starch in the ratio of 2:0(F1), 2:1(F2), 1:1(F3), 1:1.5(F4), 1:2(F5), 0:2(F6) with added carboxymethyl cellulose (15%, w/w of starch). The film F5 had superior barrier, mechanical and thermal properties over the other films. Water vapor permeability, moisture absorption, water solubility, breakage strength and elongation capacity of F5 film were reported as 1.21 × 10(-9)g/Pa h m, 9.37%, 40%, 977.3g and 14.62 mm respectively. However, surface characteristics showed the smooth and uniform film and thermal decomposition took place above 200 °C. The film forming solution of selected F5 film, added with antioxidant and antimicrobial extracts was coated on bamboo shoots and stored for 5 days. The film was successful in lowering the browning of bamboo shoots, and also successfully inhibited surface microbial load. Moreover, the moisture loss of coated shoot was less compared to uncoated.

Modeling and optimization of the process parameters in vacuum drying of culinary banana (Musa ABB) slices by application of artificial neural network and genetic algorithm

ABSTRACT The influence of drying temperature, sample slice thickness, and pretreatment on quality attributes like rehydration ratio, scavenging activity, color (in terms of nonenzymatic browning), and texture (in terms of hardness) of culinary banana (Musa ABB) has been evaluated in the present study. A comparative approach was made between artificial neural network (ANN) and response surface methodology (RSM) to predict various parameters for vacuum drying of culinary banana. The effect of process variables on responses during dehydration were investigated using general factorial experimental design. This design was used to train feed-forward back-propagation ANN. The predictive capabilities of these two methodologies for optimization of process parameters were compared in terms of relative deviation (Rd). Results revealed that a properly trained ANN model is found to be more accurate in prediction as compared to RSM. The optimum condition selected from ANN/GA responses on the basis of highest fitness value revealed that culinary banana slices of 6 mm thickness pretreated with 1% citric acid and dried at 76°C resulted in a maximum rehydration ratio of 6.20, scavenging activity of 48.63% with minimum nonenzymatic browning of 25%, and hardness of 43.63 N. Results further revealed that, in the case of rehydration ratio, temperature and pretreatment showed a positive effect while thickness had a negative effect. On the contrary, for scavenging activity, temperature showed the highest negative effect followed by slice thickness and positive effect with pretreatment. For nonenzymatic browning, thickness showed the highest negative effect but temperature and pretreatment showed a positive effect. Similarly, for hardness, all three parameters showed a negative effect.

In Vitro Antioxidant Activities of Polyphenols Purified from Four Plant Species Used in Rice Beer Preparation in Assam India

The purified phenolic extracts of Artocarpus heterophyllus, Oldenlandia corymbosa, Cyclosorus extensa, and Alpinia malaccensis were tested for the presence of various polyphenols and antioxidant activities. The polyphenols were extracted with ethanol and purified by stepwise dialysis and column elution. High-performance liquid chromatography was performed to detect and quantitate the polyphenols and 10 different in vitro methodologies were used to measure antioxidant properties. Quercetin, ferulic acid, and salicylic acid were present in all the species. Chlorogenic and p-coumaric acid in A. heterophyllus; p-coumaric acid, caffeic acid, naringin, catechol, and resorcinol in C. extensa; chlorogenic, caffeic, and quinic acid in O. corymbosa and naringin, quinic acid and catechol in A. malaccensis were detected with varied concentrations. The 2-deoxyribose, 1,1-diphenyl-2-picryl-hydrazyl and 2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) assays exhibited high radical scavenging activities and they were also able to combat •OH radicals and H2O2 to an extent of 25.53 and 71.23% respectively. Superoxide anions and nitric oxide radicals were scavenged up to 63.85 and 56.24%, respectively, and the extracts exhibited ferric ions chelation and ferrous ions reduction capacity. A reduction in the level of lipid peroxidation was also observed. All four species were found to be potent sources of polyphenols having antioxidative property. The results fully justified the use of these plants in the beer making process of Assam, India.

Optimization of Microwave Assisted Extraction of Antioxidant Extract from Garcinia pedunculata Robx.

The process of microwave assisted extraction of antioxidants extract from Garcinia pedunculata Robx. was optimized using response surface methodology. A Box-Behnkem design was used to investigate the effects of three independent variables, namely solvent concentration(%), solvent to sample ratio(v/w), and radiation time(min) on total antioxidant activity by DPPH and ABTS radical scavenging activity. Optimal conditions for extraction of antioxidants concluded that the solvent concentration be 70.79%, solvent to sample ratio be 20:1, and irradiation time at 4.73 minutes. However, the antioxidant activity of the extract was found to reach upto 85.98% DPPH radical scavenging activity and 19.23 mg-trolox equivalent/g dry weight. FTIR study revealed that, the extraction of antioxidant extract was higher with increase in irradiation time, but the antioxidant activity of the extract was lower with increase in time. The structural changes in plant material after extractions observed by light microscopy provided visual evidence of the disruption effect.

Drying Characteristics and Assessment of Physicochemical and Microstructural Properties of Dried Culinary Banana Slices

Abstract This study quantifies the drying characteristics and quality attributes of culinary banana at various temperatures (40–70°C) which exhibited falling rate period. Among the different drying models, Wang and Singh model was found the best fitted model with lowest Ӽ2 and highest R2 values. The coefficients of Wang and Singh model were expressed in nonlinear form as a function of temperature and a new model was developed in which moisture ratio is expressed as a function of time and temperature. Effective moisture diffusivity increased with increase in drying temperature. Scanning electron micrographs showed that samples dried at 70°C produced larger pores which resulted in better rehydration ratio and minimum hardness. The nonenzymatic browning occurred faster at 70°C and in addition, the chemical properties were not significantly affected by drying temperatures.

Pigmented rice a potential source of bioactive compounds: a review

Summary Rice (Oryza sativa L.) is one of the most important food crops in the world. In red rice, black, purple, brown, and brown red rice, major bioactive components are gallic, protocatechuic, hydroxybenzoic, p-coumaric,ferulic, sinapic acid, cyanidin-3-O-glucoside, peonidin-3-O-glucoside,flavan-3-ol (+) catechin and (−) epicatechin,flavanols (flavan- 3-ols), isoflavones, γ-oryzanol contents, compositions of steryl, triterpene alcohol ferulates proportions, and tocopherols, etc. This review provides information of pigmented rice in the form of bioactive compounds, concentration, activities and its healths benefit. These bioactive compounds are having immense potential for many health benefit effects and can act as antitumour, anti-atherosclerosis, anti-diabetic, anti-allergicagents, alleviating gallstones, anticancer activity, anti-inflammatoryeffects, and others.

Effect of repeated cycled crystallization on digestibility and molecular structure of glutinous Bora rice starch

The effects of repeated cycled crystallization on the digestibility and molecular structure of glutinous Bora rice starch were investigated. Temperature cycle 4/45°C; cycle duration 5d; time interval of cycles 24h; and starch to water ratio 1:2 were found to be optimum for SDS (slow digestible starch) product development. The SDS content increased from 18.01±2.11% to 82.81±2.34%. An increase in the resistance to digestion, crystallinity, molecular weight, polydispersity and molecular order was observed in the optimal SDS product. Notably, the FT-IR peak at 947cm-1 and XRD peaks at 2θ≈13° and 20° in the optimal SDS product indicated the formation of V-type complexes even without the presence of co-polymers. Birefringence studies showed a loss of typical Maltese cross in the SDS product and revealed a reorientation of crystalline structures within starch granules, suggestive of imperfect crystallite development.

Functional and reconstitution properties of spray-dried sweetened yogurt powder as influenced by processing conditions

ABSTRACT The influence of spray-drying conditions on functional and reconstitution properties of sweetened yogurt powder was studied. Twenty experiments with different spray-drying conditions (140–180°C inlet air temperature, 0.3–0.6 L/h feed rate and 500–1000 kPa atomization pressure) were performed according to central composite experimental design. Analysis of experimental data of solubility and dispersibility of yogurt powder revealed negative correlation with inlet air temperature and atomization pressure. Solubility of powder was significantly (p < 0.05) affected by feed rate. Wetting time of powder increased significantly (p < 0.001) with the increase of spray-drying temperature. The bulk, tapped, and particle densities were in the range of 344.8–475.7, 551.7–782.5, and 1187.5–1666.7 kg/m3, respectively. A significant quadratic effect (p < 0.001) of inlet air temperature and atomization pressure was observed on bulk density. Particle density increased with the increase in inlet air temperature and atomization pressure (p < 0.001). The results of the present investigation has the credible evidence to support that the processing conditions viz. inlet air temperature and atomization pressure decreased the water activity and flow property of the sweetened yogurt powder, whereas feed rate showed positive effect.