Parimal Chattopadhyay

Application of principal component analysis (PCA) as a sensory assessment tool for fermented food products

The objective of the work was to use the method of quantitative descriptive analysis (QDA) to describe the sensory attributes of the fermented food products prepared with the incorporation of lactic cultures. Panellists were selected and trained to evaluate various attributes specially color and appearance, body texture, flavor, overall acceptability and acidity of the fermented food products like cow milk curd and soymilk curd, idli, sauerkraut and probiotic ice cream. Principal component analysis (PCA) identified the six significant principal components that accounted for more than 90% of the variance in the sensory attribute data. Overall product quality was modelled as a function of principal components using multiple least squares regression (R2 = 0.8). The result from PCA was statistically analyzed by analysis of variance (ANOVA). These findings demonstrate the utility of quantitative descriptive analysis for identifying and measuring the fermented food product attributes that are important for consumer acceptability.

Biosorption of Malathion by immobilized cells of Bacillus sp. S14

Abstract Biosorption is potentially an attractive technology for the treatment of wastewater by removing pesticide molecules from dilute solutions. This study investigated the feasibility of an isolated Bacillus sp. S14 immobilized in calcium alginate that was used as a biosorbent for Malathion removal from aqueous solutions in batch mode. The highest value of Malathion uptake by isolated Bacillus sp. S14 (1.33g L−1, dry basis) immobilized in 3% calcium alginate was 64.4% at 25°C and pH7.0 when the initial Malathion concentration was 50 mg L−1. Equilibrium was attained at 8h. The sorption data conformed well to the Fruendlich isotherm model.

Continuous removal of malathion by immobilised biomass of Bacillus species S14 using a packed bed column reactor

Abstract Biosorption of malathion from aqueous solution was studied using Bacillus sp. S14 immobilised on calcium alginate (3%) using a packed bed column reactor at a temperature of 25 °C and a pH of 7.0. The experiments were conducted to study the effect of important design parameters such as bed height, flow rate and influent malathion concentration. Maximum removal capacity (57%) was found at 4 mL min-1 flow rate, 6.0 cm bed height and 25 mg L-1 influent malathion concentration. The Adam-Bohart model, Wolborska model, Thomas model, Yoon-Nelson model were employed to determine characteristic parameters such as saturation concentration, external mass transfer coefficient, Thomas rate constant, the maximum solid phase concentration of the solute, rate constant, and the time required for 50% adsorbate breakthrough time, which are all useful for process design. Experimental data were well fitted with Adam–Bohart model at the lower region of effluent/influent malathion concentration values but at higher region values data fitted well with the Thomas and Yoon-Nelson models.

Biosorption of malathion by dry cells of an isolated Bacillus sp. S14.

Abstract The removal of Malathion, a moderately toxic organophosphate pesticide causing environmental pollution, from dilute aqueous solutions was studied. The experimental results showed that the dry cells of Bacillus sp. S14 were effective in removing Malathion from solution. Biosorption equilibrium was attained within 6h. Maximum biosorption of Malathion (81.4%) was observed under the following environmental conditions, pH 6.5, temperature 25°C, dry biomass concentration 1g L−1 at 6h. Both Langmuir and Freundlich isotherms were tested and the latter had a better fit with the data. The dried powdered cells of Bacillus sp. S14 can be safely stored for 60 days at room temperature without any loss of biosorption efficiency. The results suggest that the dry cells of the isolated Bacillus sp. S14 can be used as a biosorbent for an efficient removal of Malathion from aqueous solutions.

FREEZING OF FOODS | Growth and Survival of Microorganisms

The low-temperature preservation of foods is based on the principle that the activities of foodborne microorganisms can be slowed down at temperatures around the freezing point and stopped at temperatures below the freezing point. The metabolic reactions of microorganisms are catalyzed by enzymes and the rate is dependent on temperature. The rate of reaction is increased with an increase in temperature. The temperature coefficient (Q 10 ) value varies between 1.5 and 2.5. The temperature always is related to the relative humidity of the reaction environment and therefore subfreezing temperatures also affect the relative humidity and the pH of the system for microbial growth.

Biosorption of Malathion using dry cells of Bacillus species S14 in a packed bed column reactor

Abstract The ability of dried bacterial strain Bacillus sp. S14 to adsorb Malathion in a packed bed column reactor was studied. The effects of important design parameters such as bed height, flow rate and influent Malathion concentration on Malathion removal from an aqueous solution was studied using a packed bed column reactor. The optimised conditions for maximum Malathion removal were found to be: flow rate: 5 mL min-1, bed height: 6.0 cm and influent Malathion concentration: 25 mg L-1. The Adams-Bohart model, Wolborska model, Thomas model, Yoon and Nelson Model were employed to determine characteristic parameters such as N0 (saturation concentration, mg L-1), βo (external mass transfer coefficient, min-1), k Th(Thomas rate constant, mL min-1mg-1), q0 (maximum solid phase concentration of the solute, mg L-1), kYN (rate constant, min-1) and τ (time required for 50 % adsorbate breakthrough time, min) which are useful for process design. Data were fitted with Adams-Bohart model at lower region of (C/C0) values but more accurately fitted with Wolborska and Thomas model.

Process of Fortification of Cow Milk Curd with Beta (ß) Carotene Producing Sweet Potato

Sweet potato (SP) is the world’s seventh most important tropical food crop after wheat, rice, maize, potato, barley and cassava. Pigments present in sweet potato namely, s-carotene, anthocyanin and unidentified flavonoids are regarded as antioxidants. As SP roots are rich in starch, sugars, minerals, vitamins and dietary fiber, they have high potential for undergoing fermentation into value-added commodities like curd, yogurt, pickles, amongst others. Added s-carotene rich SP provided vitamin A, starch, dietary fiber that functioned as thickener and stabilizer. In the present study, s-carotene rich SP curd was prepared by fermenting (hyphenate these two words) 16 % SP and cow’s milk. The samples were subjected to consumer evaluation that was modeled using logistic regression to identify which sensory attributes determine acceptability of the product. Our results showed that texture and color significantly influence consumer acceptability. Addition of SP enriched curd with dietary fiber and starch improved the firmness of the curd.

Production and Characterization of a Crude Thermostable Invertase from Cryptococcus laurentii S23

Abstract A yeast strain isolated from soil and identified as Cryptococcus laurentii was found capable of producing thermostable extracellular invertase. The extracellular enzyme was thermostable, and the optimum temperature, pH and time for enzyme-substrate reaction were found to be 60°C, 5.5 and 5 min, respectively. Mn2+ stimulated the activity of enzyme significantly while Co2+, Ca2+, Cu2+ and Fe3+ showed little stimulatory effects. Cetyltrimethylammonium bromide showed stimulatory and ethylenediaminetetraacetic acid showed inhibitory effects on enzyme activity. Enzyme was found to be thermostable up to 60°C at pH 5.5. The maximum invertase production (35.32 IU ml−1) was achieved at 30°C, 120 rpm and pH 4.5 on 48 h using 1.0% cell suspension (24 h old) as inoculum in 50 ml medium in 250 ml Erlenmeyer flask. The superior carbon and nitrogen sources for the production of invertase were found to be sucrose (2.0%), peptone (nitrogen level 1 mg/ml). The Km and Vmax were 2.9 mg ml−1 and 39.7 mg min−1 ml−1, respectively. The maximum enzyme activity obtained was 44.72.

Bioremediation of Malathion from Environment by an Isolated Bacillus sp. S14

Abstract Pesticide pollution has been increased owing to their growing use to increase agricultural productivity. Pesticide residues are causing serious ecological problems as they are harmful to nontarget organisms. Physical and chemical methods of removal of pesticide molecules often involve a lengthy and expensive treatment process. In this respect bioremediation of pesticide is more effective. A bacterial strain Bacillus species (S14) capable of removing Malathion was isolated and identified in our laboratory. Maximum Malathion removal (68%) using growing cells was observed under the following environmental conditions: 50 ml medium in a 250 ml Erlenmeyer flask, pH 7.5, temperature 28°C, shaker speed 120 rpm, initial Malathion concentration 50 mg/l, inoculum concentration 4% (20 h cell suspension). Maximum Malathion uptake (90.09%) by the isolated strain occurred at pH 6.5, temperature 25°C, using 0.32 g/l washed biomass (dry basis) in 6 h. Freundlich isotherm had a better fit with the data. Scanning electron micrographs exhibited adsorption of the pesticide on the cell surface of the Bacillus species (S14). Functional groups responsible for biosorpton were identified by infrared spectral analysis. Different functional groups, such as amine, amide present on cell surface are mainly responsible for adsorption process.