Parameswarakumar Mallikarjunan

Optimizing the Extraction of Phenolic Antioxidants from Peanut Skins Using Response Surface Methodology

Peanut skins are a byproduct of peanut blanching operations and contain high levels of phenolic antioxidants. The effect of solvent type (methanol MeOH, ethanol EtOH, and water), concentration (0, 30, 60, 90%), temperature (30, 45, 60 degrees C), and time (10, 20, 30 min) on total phenolic content (TPC), oxygen radical absorbance capacity (ORAC) level, and resveratrol content of peanut skins was investigated. Response surface methodology was used to estimate the optimum extraction conditions for each solvent. EtOH extracts had the highest TPC followed by MeOH and water. The maximum predicted TPC under the optimized conditions (30.8%, 30.9 degrees C, 12 min) was 118 mg of gallic acid equivalents (GAE)/g of skins. MeOH extracts had the highest ORAC activity of 2149 micromol of TE/g followed by EtOH and water under the optimized conditions of 30% MeOH, 52.9 degrees C and 30 min. Resveratrol was identified in MeOH extracts but was not found in samples extracted with EtOH or water.

The determination of frying oil quality using a chemosensory system

Chemosensory systems are currently being introduced in the food industries for quality control and process monitoring. This study was conducted to determine the possibility of using a chemosensory system to differentiate among varying intensities of oil rancidity and investigate discrimination between good, marginal and unacceptable frying oils. Fresh, 1-day, 2-day used and discarded frying oils were obtained from a fast food restaurant in each frying cycle for 4 weeks. The oil samples were analysed using a quartz-microbalance-based chemosensory system. The discrimination between good, marginal and unacceptable frying oils with regard to rancidity was examined and the results were compared to their physico-chemical properties such as dielectric constant, peroxide value, and free fatty acid content. The different qualities of frying oils were successfully evaluated and discriminated using the chemosensory system. Good correlations (r from 0.87 to 0.96) were found between changes in physico-chemical properties of oil and the sensor signals.

Modeling of heat transfer and evaporative mass losses during the cooking of beef patties using far-infrared radiation

Abstract Heat and mass transfer during the cooking of beef patties by long wavelength, far-infrared radiation was studied. A one-dimensional model based on an infinite slab is described, the model was solved using the finite difference technique. The results obtained from the model were compared to experimental results over a range of fat contents from 0% to 30% fat. Heat transfer results for the 0% fat content, using a conduction model showed very good agreement with the experimental data (r2=0.99), however, when the same model was used for the higher fat contents, model prediction was poor. By including a term to account for internal fat and moisture convection in the beef patties during cooking, the heat transfer process could be predicted for fat contents ranging from 10% to 30% fat, with good agreement obtained with the experimental data (r2=0.99). In the prediction of the evaporative mass losses, prediction of the diffusion coefficient based on temperature and moisture content, allowed for excellent agreement with the experimental data (r2=0.99). Thus it was concluded that the model described the cooking of beef patties using far-infrared radiation over a range of fat contents. The effects of internal fat and convective mass transfer during cooking were accounted for during development of the model.

Heat and mass transfer during beef carcass chilling — Modelling and simulation

Abstract This paper describes the development of a two-dimensional heat and mass transfer model of beef carcass chilling. The model includes thermal properties as functions of temperature and composition. The carcass was divided into five zones, i.e. round, sirloin, loin, rib and chuck, and the carcass cross-sectional structure within a zone was considered uniform. The model was solved using finite element method. Temperature and mass histories were collected for three chilling schemes to validate the model. The simulated results are in good agreement with the observed data, and predicted temperature and mass histories within 2·7°C and 0·4%, respectively.

Inactivation of Vibrio parahaemolyticus and Vibrio vulnificus in phosphate-buffered saline and in inoculated whole oysters by high-pressure processing

Inactivation studies for Vibrio parahaemolyticus TX-2103 (serotype O3:K6) and Vibrio vulnificus MO-624 (clinical isolate) were conducted in phosphate-buffered saline (PBS) and in inoculated oysters under high-pressure processing conditions. V. parahaemolyticus was more resistant than V. vulnificus in PBS at all pressures and times. A 6-log reduction of V. parahaemolyticus and V. vulnificus in PBS at 241 MPa required 11 and 5 min, respectively, which included a 3-min pressure come-up time. A 4.5-log reduction of V. parahaemolyticus in oysters at 345 MPa required 7.7 min, which included a 6.7-min pressure come-up time. More than a 5.4-log reduction of V. vulnificus in oysters at 345 MPa occurred during the 6-min pressure come-up time. Both V. parahaemolyticus and V. vulnificus in PBS and in oysters were reduced to nondetectable numbers at 586 MPa during the 8- and 7-min pressure come-up times, respectively.

Comparison of kinetic models to describe high pressure and gamma irradiation used to inactivate Vibrio vulnificus and Vibrio parahaemolyticus prepared in buffer solution and in whole oysters.

Comparisons of different models in inactivation kinetics were conducted on data obtained from high-pressure and gamma-irradiation processing. Vibrio vulnificus (MO-624) and Vibrio parahaemolyticus (O3:K6 TX-2103) suspended in phosphate-buffered saline (pH 7.4, 10(7) CFU/ml) were exposed to pressures from 207 to 379 MPa for 1 to 20 min. Inoculated whole oysters (106 CFU/g) were exposed to pressure from 276 to 379 MPa for 1 to 15 min. Pure cultures and inoculated oysters (10(6) CFU/g) also were irradiated (gamma irradiation) at doses of less than 3 kGy. Four mathematical models, the Bigelow model, Arrhenius equation, Fermi equation, and Weibull frequency distributions, were applied to microbial survival data, and performances of the different kinetic models were compared. Weibull frequency distributions can predict the high-pressure inactivation of Vibrio spp. with more accuracy in both pure cultures and inoculated oyster samples. The Fermi model provided a better description of gamma-irradiation inactivation kinetics compared with the traditional Bigelow model.

EFFECT OF FAT CONTENT AND TEMPERATURE ON DIELECTRIC PROPERTIES OF GROUND BEEF

Microwave heating depends on dielectric properties, microwave frequencies, food composition, physical state of water in the food, and product temperature and density. Proper microwave cooking and thawing procedures for ground beef products are needed to ensure food safety. Recent studies showed that the fat content significantly affected the survival of pathogens. The objective of this study was to determine the effect of fat content and temperatures on dielectric properties of ground beef. The dielectric properties were determined using an open-ended, coaxial line with copper conductors, connected to a network analyzer. The relationship among dielectric properties, fat level, and temperature was obtained for 915 MHz and 2450 MHz. Results of the experiment showed that dielectric loss factor and dielectric constant increased with increase in temperature at both frequencies at temperatures below the freezing point. Above the freezing point, dielectric constant decreased with increase in temperature. Dielectric loss factor increased with temperature at 915 MHz. At 2450 MHz, it remained almost constant with varying temperature. Dielectric constant and dielectric loss factor of low-fat ground beef were higher than that of high-fat ground beef. Regression equations were developed for predicting dielectric properties at different temperatures and fat levels.

Optimizing an electronic nose for analysis of volatiles from printing inks on assorted plastic films

Abstract Volatiles from inks present in food packaging films could pose a quality problem in food products. The food industry is interested in determining a single set of optimum values for the system parameters to maximize detection levels on assorted plastic packaging films. Volatiles from ink used on nine plastic food-packaging films were analyzed using an electronic nose with six resonating quartz sensors. A response surface analysis was used to determine if the system parameters (sample temperature, equilibration time, sensor temperature and pressurization time) significantly affected the detection levels of volatile compounds. Sample temperature, equilibration time and sensor temperature were significant (α=0.05) for each of the sensors and the optimum settings for these parameters to maximize detection levels were 80 °C, 20 min, and 40 °C, respectively. The results of this study indicate potential for this electronic nose to be used as a discriminatory tool in quality control for packaging films.

Optimum Cooking Conditions for Shrimp and Atlantic Salmon

The quality and safety of a cooked food product depends on many variables, including the cooking method and time-temperature combinations employed. The overall heating profile of the food can be useful in predicting the quality changes and microbial inactivation occurring during cooking. Mathematical modeling can be used to attain the complex heating profile of a food product during cooking. Studies were performed to monitor the product heating profile during the baking and boiling of shrimp and the baking and pan-frying of salmon. Product color, texture, moisture content, mass loss, and pressed juice were evaluated during the cooking processes as the products reached the internal temperature recommended by the FDA. Studies were also performed on the inactivation of Salmonella cocktails in shrimp and salmon. To effectively predict inactivation during cooking, the Bigelow, Fermi distribution, and Weibull distribution models were applied to the Salmonella thermal inactivation data. Minimum cooking temperatures necessary to destroy Salmonella in shrimp and salmon were determined. The heating profiles of the 2 products were modeled using the finite difference method. Temperature data directly from the modeled heating profiles were then used in the kinetic modeling of quality change and Salmonella inactivation during cooking. The optimum cooking times for a 3-log reduction of Salmonella and maintaining 95% of quality attributes are 100, 233, 159, 378, 1132, and 399 s for boiling extra jumbo shrimp, baking extra jumbo shrimp, boiling colossal shrimp, baking colossal shrimp, baking Atlantic salmon, and pan frying Atlantic Salmon, respectively.

Optimum conditions for beef carcass chilling

Optimum chilling schemes for a two- or three-stage chilling system were developed using a validated heat and mass transfer model and a pattern search algorithm. The optimization was performed for the ambient temperature during each stage for an air velocity of 0·5 m/s and 90% relative humidity. The experiments were conducted to evaluate the effect of the optimum conditions on beef quality after ageing.