Prerna Khawas

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.

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.

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.

Comparative Nutritional, Functional, Morphological, and Diffractogram Study on Culinary Banana (Musa ABB) Peel at Various Stages of Development

The culinary banana peel, which is an agricultural waste available in abundance, has not been able to draw much attention in terms of its utilization. In addition to being an abundant source of functional and nutritional compounds, it also deserves to be utilized in a proper and/or better way. The aim of this study was to explore this agro-waste at different levels of maturity in order to identify the active compounds at particular stage of maturity. Phenolics, flavonoids, and radical scavenging activity were maximum at early developmental stage, whereas compounds like protein, fat, carbohydrates, and starch increased with maturity and declined at over-ripe stage. The starch present in the peel is of C-type as confirmed by x-ray diffractograms and crystalline in nature. The peel, at the edible mature stage 4, yielded a high cellulose content which could be used as a reinforcement material in high-performance biocomposites. The presence of various functional groups indicating the complex nature of the culinary banana peel was confirmed by Fourier transform infrared characterization. Scanning electron microscope micrographs revealed that microstructure of peel changes drastically and degradation of starch and other compounds occurred at the over-ripe stage. Hence, in this context, the culinary banana peel can serve as a potential biomaterial in industrial applications and can add a higher value to this locally important and underutilized crop.

Phytochemical Constituents, Attenuated Total Reflectance Fourier Transform Infrared Analysis and Antimicrobial Activity of Four Plant Leaves Used for Preparing Rice Beer in Assam, India

Phytochemicals content and antimicrobial activity of Artocarpus heterophyllus, Cyclosorus extensa, Oldendia corymbosa, and Alpinia malaccensis were investigated. Maximum alkaloids and terpenoids were found in A. heterophyllus; tannins and saponins in C. extensa; flavonoids, polyphenols, and phytosterols in O. corymbosa and anthraquinone, glycosides, and anthocyaninin A. malaccensis. Aqueous, methanolic, ethyl acetate, and hexane extracts were prepared from all the leaves. Attenuated total reflectance Fourier transform infrared spectrophotometric (ATR-FTIR) analysis revealed that alkanes and alkyl halides were prevalent in all the extracts and the ethyl acetate extracts contained comparatively higher number of functional groups, which were also more effective against Candida albicans, Escherichia coli, and Staphylococcus aureus. The minimum inhibitory concentration values of A. malaccensis against the tested pathogens were found to be lesser than the other species.

Effect of modified resistant starch of culinary banana on physicochemical, functional, morphological, diffraction, and thermal properties

ABSTRACT Resistant starch has received much attention for both its potential health benefits and functional properties. The present study revealed that the culinary banana can be a potential source for production of resistant starch type III. The results showed that resistant starch yield can be increased using debranching enzyme (Pullulanase EC 3.2.1.41) and hydrothermal process. The three repeated autoclaving and cooling (hydrothermal) cycles followed by storage at –20ºC, increased the resistant starch yield from 12.3 to 26.4%. The use of debranching enzyme and subsequent retrogradation at –20ºC increased the resistant starch yield up to 31.2%. The modified resistant starch when compared to culinary banana starch evinced better stability. The modified resistant starch was analyzed using scanning electron microscopy, Fourier transform infrared, x-ray diffraction, and thermogravimetric diffraction analysis to determine the structural changes which proved that the modification occurred substantially.

Optimization of the extraction of phenolic compounds from Cyclosorus extensa with solvents of varying polarities

ABSTRACT The leaves of Cyclosorus extensa are used in the preparation of rice beer in Assam, India. The optimal conditions of time and temperature of fermentation for extraction of bioactive compounds from the dried leaves were obtained using response surface methodology. The central composite rotatable design was used and 13 experimental runs based on two-factor-five-level design were generated and performed for each of the solvents. The independent variables were extraction time (12 and 48 h) and temperature (25 and 55°C). The responses studied were total polyphenol content, radical scavenging activity, antibacterial activity, and antifungal activity. The analysis of variance of the test data was performed and the sequential sum of squares, F-value, R2, and adjusted R2 were deduced. The predicted models for all the response variables were adequately fitted to the observed experimental data (p ≤ 0.001). The maximum extraction of bioactive compounds under the optimum conditions of extraction temperature and time for hexane, ethyl acetate, methanol, and distilled water were found to be 25°C for 29.43 h, 28.28°C for 41.27 h, 43.95°C for 29.61 h, and 55.00°C for 48.00 h, respectively. It was also observed that the solubility of the polyphenols was higher in methanol, followed by ethyl acetate, and the highest antibacterial activity against Escherichia coli was shown by the ethyl acetate extracts.