Paramita Bhattacharjee

Studies on fermentative production of squalene

Fermentative production of squalene under anaerobic conditions using commercially available compressed bakers yeast (Saccharomyces cerevisiae), and a strain of Torulaspora delbrueckii isolated from molasses was studied. Yield of squalene from S. cerevisiae and T. delbrueckii were found to be 41.16 and 237.25 μg g−1 respectively, dry weight of yeast cells. Isolation and purification of squalene from the lipid extracts obtained by cell lysis of either strain were achieved chromatographically. The purified squalene was characterized spectroscopically against an authentic standard.

Hydrocarbons as marker compounds for irradiated cashew nuts

Abstract Volatile long chain hydrocarbons, such as 1-tetradecene, 1-hexadecene and 8-heptadecene, could serve as marker compounds in cashew nuts irradiated at 0.25–1.00 kGy. Monitoring these markers over a storage period of 6 months under ambient conditions showed them to be persistent. The concentrations of the markers increased linearly with radiation dose at all storage periods of the study. However, their concentration decreased marginally with storage at all the dose levels.

Enzyme-assisted supercritical carbon dioxide extraction of black pepper oleoresin for enhanced yield of piperine-rich extract

Black pepper (Piper nigrum L.), the King of Spices is the most popular spice globally and its active ingredient, piperine, is reportedly known for its therapeutic potency. In this work, enzyme-assisted supercritical carbon dioxide (SC-CO2) extraction of black pepper oleoresin was investigated using α-amylase (from Bacillus licheniformis) for enhanced yield of piperine-rich extract possessing good combination of phytochemical properties. Optimization of the extraction parameters (without enzyme), mainly temperature and pressure, was conducted in both batch and continuous modes and the optimized conditions that provided the maximum yield of piperine was in the batch mode, with a sample size of 20 g of black pepper powder (particle diameter 0.42 ± 0.02 mm) at 60 °C and 300 bar at 2 L/min of CO2 flow. Studies on activity of α-amylase were conducted under these optimized conditions in both batch and continuous modes, with varying amounts of lyophilized enzyme (2 mg, 5 mg and 10 mg) and time of exposure of the enzyme to SC-CO2 (2.25 h and 4.25 h). The specific activity of the enzyme increased by 2.13 times when treated in the continuous mode than in the batch mode (1.25 times increase). The structural changes of the treated enzymes were studied by (1)H NMR analyses. In case of α-amylase assisted extractions of black pepper, both batch and continuous modes significantly increased the yields and phytochemical properties of piperine-rich extracts; with higher increase in batch mode than in continuous.

Extraction of squalene from yeast by supercritical carbon dioxide

Squalene produced under anaerobic conditions, by a strain of Torulaspora delbrueckii was extracted from the biomass using supercritical carbon dioxide. Minimum use of solvent, lower time of isolation and a higher selectivity of extraction merit use of supercritical fluid extraction (SFE) technique over solvent extraction of squalene, as optimized and reported previously. A maximum squalene yield of 11.12 μg g−1 (dry weight) of yeast cells was obtained at a temperature of 60 °C and pressure of 250–255 bar at a constant flow rate of 0.2l min−1 of carbon dioxide. Lyophilization prior to SFE increased the squalene yield to 430.52 μg g−1 dry weight of yeast cells, an amount that is far greater than that obtained by (2:1) chloroform–methanol solvent extraction.

Compositional profiles of γ-irradiated cashew nuts

Cashew nuts, an important export item from India, contribute to about 7% of the national exchequer. Insect infestation of the cashew nut, leading to economic losses is a frequently encountered problem. The present work aims to combat this problem by using low dose γ-irradiation and evaluating the effect of such treatment on the physico-chemical properties of cashew nuts. Cashew nuts, irradiated at 0.25, 0.50, 0.75 and 1.00 kGy and stored under ambient conditions were analyzed periodically every 2 months for 6 months with respect to the changes in 10-kernel weights, colour characteristics and proximate composition. Visual inspection showed no insect infestation for six months, even at 0.25 kGy, while the control sample was totally infested. This was evident from the 10-kernel weights, which decreased gradually with time of storage. While an increase in yellowness of the cashew nuts was observed as a function of storage time and irradiation dose, no substantial changes in proximate composition between the samples or with storage time were observed. This study underlines the use of 0.25 kGy of irradiation for preservation of cashew nuts.

A comparative study on the physical characteristics and cooking quality parameters of commercial brands of Basmati rice.

Randomly selected samples of three popular commercial brands of Basmati rice (designated as A, B and C) available in Mumbai city were studied with respect to their proximate composition and differences in their quality evaluated in terms of length by breadth and elongation ratio, differential length by breadth ratio, water uptake, loss of solids in cooking water, swelling index and volume expansion ratio. The l/b ratio and elongation ratio varied between 4.47 to 4.81 and 1.45 to 1.59 respectively. The differential length by breadth ratio showed a wide variation from 5.88 to 9.48 among the three brands studied. Brand A recorded the highest length by breadth and elongation ratio whereas brand C recorded the highest differential length by breadth ratio. The water uptake values and the loss of solids in the cooking gruel varied between 172 to 262 and 0.87 to 2.70 (g/100 g of rice) respectively, among the three commercial brands. The swelling index and the volume expansion ratio did not show much variation among the three brands ranging between 28 to 31 for the former and 2.00 to 2.21 for the latter. Based on the differential length by breadth ratio, water uptake and swelling index values, which are the most reliable quality indices; brand C was found to be the best followed by brands A and B. The study of the texture of the cooked rice grains indicated that brand C had the softest grains, which was in conformity with the findings in cooking quality characteristics.

Mathematical modeling of supercritical carbon dioxide extraction of methyl eugenol from tuberose flowers

Methyl eugenol-rich extracts from dried tuberose flowers (Polianthes tuberosa L.) of Calcutta single variety were obtained using supercritical carbon dioxide (SC-CO2) extraction. The optimized conditions for highest yield of methyl eugenol were 50 °C, 300 bar, 135 min with 1 L min−1 flow rate of gaseous CO2. Solubilities of methyl eugenol under different SC-CO2 extraction conditions were evaluated by Hildebrand solubility parameter and Chrastil equation. The extraction curve of methyl eugenol followed plug flow model. Steady state extraction occurred up to 100min, followed by unsteady state. Release of methyl eugenol from tuberose flowers followed first-order kinetics (Peppas model) and non-Fickian diffusion. Packed bed characterization was carried out using dimensionless numbers of mass transfer, considering steady and unsteady states of extraction. These findings could be used in the development of the pilot plant and commercial scale extraction of methyl eugenol from floral matrices.

Facile and rapid thermo-regulated biomineralization of gold by pullulan and study of its thermodynamic parameters

A novel method for the production of gold nanoparticles (AuNPs) using pullulan as reducing and stabilizing agent has been developed. Quasi-spherical shaped AuNPs in the range of 50-100 nm were produced at three different temperature regimes 80°C, 90°C and 100°C as characterized using UV-vis spectrophotometer, TEM and DLS. Study of reaction kinetics and thermodynamic parameters indicated that the reaction between pullulan and chloroauric acid for AuNPs formation followed first order reaction kinetics and higher temperature was favorable for the synthesis of smaller sized AuNPs. FT-IR data analyses, provided an insight towards the mechanism of gold nanoparticle formation which suggested that, the free CH2OH groups of pullulan molecule were oxidized to carboxylate ions resulted in formation of AuNPs whereas the basic skeletal structure of pullulan remained unaltered. This study may open up new avenues for synthesis of tailor made biogenic AuNPs with possible application in biomedical field.

STUDY OF HEADSPACE GASES ASSOCIATED WITH SALMONELLA CONTAMINATION OF STERILE BEEF IN VIALS USING HS-SPME/GC-MS

Sterile beef (fresh strip loins) samples were inoculated with Salmonella typhimurium, and both control and inoculated samples were stored at 20°C in 20 mL headspace vials covered with food-grade cling film. An array of volatile compounds was detected in the headspace of the control and inoculated samples. The study was conducted for four days, and the volatiles in the headspace were analyzed each day using manual headspace solid-phase microextraction (HS-SPME) in combination with gas chromatography-mass spectrometry (GC-MS). Acetic acid, ethanol, carbon dioxide, and 3-hydroxy-2-butanone were the most prominent compounds detected in the study. The F-tests (Fishers variance ratio) for the main effect of the sample source established acetic acid and ethanol as compounds of interest for monitoring the status of Salmonella in raw fresh beef. Good linear correlations were found between the logarithms of the peak area responses of these compounds with Salmonella count.

Spray Dried Extract of Phormidium valderianum as a Promising Source of Natural Antioxidant

Microencapsulation of antioxidant-rich fraction obtained by supercritical carbon dioxide extraction (at 50°C, 500 bar with extraction time of 90 min, and flow rate of CO2 at 2 L/min) of lyophilized biomass of Phormidium valderianum was carried out in a spray dryer using maltodextrin and gum arabic. Microencapsulation conditions that provided the best combination of phytochemical properties such as antioxidant activity, phenolic content, and reducing power with reasonable powder yield were an inlet temperature of 130°C and wall material composition as maltodextrin: gum arabic = 70 : 30. Toxicological study reported that the Anatoxin-a content of this encapsulated powder was below the limit of detection of HPLC. Storage study established that encapsulation of this antioxidant-rich algal extract resulted in eight times enhancement of half-life (T 1/2) values. The release profile of microencapsulated antioxidant-rich fraction from the encapsulated powder was found to follow first order anomalous transport kinetics. Therefore, this microencapsulated algal extract with minimum toxicity is a source of natural antioxidant and could have promising use as novel dietary supplement.