Volume 6, Issue 3

The influence of temperature and water content on thermophysical properties (density, thermal diffusivity, thermal conductivity and specific heat) of genipap (Genipa americana, L) pulp at medium maturity were studied. The thermophysical properties were determined at concentrations between 6.0% m/m and 24.0% m/m of water content and temperatures range of 5 to 80°C. The density decreased with increase in temperature and water content, while the thermal diffusivity and conductivity increased as temperature and water content increased. The specific heat decreased with the moisture content. Empirical models were fitted to the experimental data for each property and the accuracy of those models was checked.

The physicochemical properties of extruded starches from wheat, maize and rice were compared. These samples were extruded with a twin-screw extruder at varying water feed rates of 1.78, 1.25, 0.70, 0.35 and zero kg/h. The expansion of the samples (producing puffed products in all cases) increased with increasing the specific mechanical energy (SME). However maize flour produced the most expanded product, whilst rice samples produced the least expanded one. The cold-water viscosity of the samples at 25.0°C measured by the RVA were different; for wheat samples it decreased with increasing the SME input, for rice samples it showed a reverse relationship with the SME and for maize samples it was rising at lower SME inputs and then falling at higher SMEs. The x-ray diffraction patterns of extruded starches changed from the “A-pattern" to “V"- and “E"- patterns. Determination of the apparent sedimentation coefficients at a constant concentration (s* value) of amylose and amylopectin of the samples showed that degradation of mainly amylopectin could occur during extrusion cooking. Differences in composition and molecular structure of these samples along with the breakdown of amylopectin may be the key factors in explaining the different physicochemical behaviors of these samples.

Microwave-assisted extraction (MAE) was compared with room temperature extraction (RTE) and reflux temperature extraction (RFX) on the extraction of ginsenosides from fresh American ginseng root. The influence of various factors, i.e. extraction method, solvent type, solvent to sample ratio, extraction time, and the size of sample particles on the extraction of ginsenosides Re, mRb1, Rb1 and total ginsenosides was studied. An 86 to 300% increase in extraction rate was observed with extraction under raised temperature in the microwave. Using microwave energy instead of hotplate-heating for the extraction resulted in a 31 to 96% increase in extraction rate. Visual analysis of the chromatograms of extracts can help the selection of extracting conditions for selectively obtaining specific ginsenosides enriched extracts.

Pulsed electric fields (PEF) were utilized for inhibition of polyphenoloxidase (PPO) of pear. The effects of PEF electric field strength, treatment time and the temperature on the reduction of PPO activity were evaluated in this study. A maximum of 95.5% inactivation of pear PPO was observed with the PEF treatment at 35 kV/cm for 1200 ?s at 40°C. The classical first-order inactivation as well as modified Hülsheger’s kinetic model adequately described the enzymatic inhibition in PEF processing. The second-order polynomial equation was a suitable model to analyze the inactivation of PPO using PEF technology since the PEF parameters such as PEF electric field strength, treatment time and temperature could be involved in this model.

Artificial neural network models were developed for the overall heat transfer coefficient (U) and the fluid to particle heat transfer coefficient hfp in canned Newtonian fluids with and without particles, and the model performances were compared with the dimensionless correlations for both free and fixed axial modes of agitation. Part of the experimental data were used for training and testing, and a portion was used for cross validation. The average errors (RMS), associated with predicted hfp and U values in fixed and free axial mode were a function of the ANN variables: number of hidden layers, number of neurons in each hidden layer, learning rule, transfer function and number of learning runs. RMS values not significantly different with number of hidden layers between one and three, and the associated RMS was minimal with a high R2 value with one hidden layer and 8 neurons. The combination of the Delta-rule and TanH transfer function also gave the lowest RMS and the highest R2. The highest R2 was achieved for the data set with 85% used for training and testing and 15 % for the cross validation in both modes of rotation, and therefore this combination was used for the development of neural network models. Mean relative errors (MRE) for ANN models were much lower compared with MRE associated with dimensionless correlations; 75-78% lower for hfp and 66% lower for U in fixed and free axial mode with particulate in liquid. Without particulates, in comparison with dimensionless correlations, the MRE for ANN models were 37% lower in end-over-end mode and 76% lower for free axial mode. Overall, ANN models yielded much higher R2 values than dimensionless correlations. The ANN coefficient matrix is included so that the models can be implemented in a spreadsheet.

Red flowers of Canna indica (Family Cannacece) were extracted in Sonicator with different solvents for the estimation of polyphenols and flavonoids using fresh as well as dry flowers. Antioxidant capacities of L- Ascorbic acid, trolox, pyrogallol and Canna flower extracts were also evaluated based on its ability to scavenge the DPPH radical, results obtained were compared with those of TEAC assay. A good correlation was observed between the two methods. The results showed that acetone extract of fresh flowers contained the highest amount of antioxidant activity 78.33 %, 89.7 mg GAE / g and 51.45 ?MT / g although the yield of the extract in the methanol was highest (34 g / 100 g). Total phenol and flavonoids content (0.96 mg GAE / 100 g) (19.89 mg QE / 100 g) were also evaluated for these extract. This is the first report on the phytochemicals and antioxidant activity from Canna indica flowers particularly for its radical scavenging activity and can be a good source of food additives.

Dehydrated carrot pomace was added in different proportions (10-30%) to rice flour. The formulation was extruded at different moisture content (17-21%), screw speed (270-310 rpm) and die temperature (110-130°C). The experimental combinations were decided based on central composite rotatable design for four variables at five levels of each variable. The lateral expansion, bulk density, water absorption index, water solubility index, hardness and sensory characteristics were measured as responses. Significant regression models were established with the coefficient of determination, R² greater than 0.70. The results indicated that pomace proportion, screw speed and temperature significantly influenced (P<0.10) lateral expansion; moisture content and screw speed for bulk density; pomace proportion and temperature for water absorption index and water solubility index, pomace proportion, screw speed and temperature for hardness and screw speed for sensory score. The compromised optimum condition obtained by numerical integration for development of extrudates were: carrot pomace of 11.75% in rice flour, moisture content 19.92%, screw speed 249.1 rpm and die temperature 114.3°C. Sensory evaluation revealed that carrot pomace could be incorporated into ready-to-eat expanded products upto the level of 11.75%.

The fructosyltransferase from Rhodotorula sp. recovered from a fermented medium, by precipitation was immobilized by adsorption onto niobium ore. Considering the biocatalyst system, the activity/pH profile moved towards more alkaline values as compared to the free enzyme system, indicating that the support affected the charge distribution between the enzyme and the support. The immobilized enzyme showed high activity and good stability at pH values of 4.5 and 6.0. The biocatalyst half-lives at 48 °C and pH values of 4.5 and 6.0 were 32 and 72 days, respectively. The kinetics for the immobilized system corresponded to that of substrate inhibition. The synthesis of fructooligosaccharides from 50% sucrose solutions was carried out in batch stirred reactors and the conversion was about 58%, similar to that with the free enzyme. Based on the biocatalyst activity, stability and process yields, the system developed in this work can be considered suitable for application in large-scale bioreactors.

To determine the separate thermal effects of extrusion, nonisothermal experiments were conducted by heating wheat flour mixed with 0.46% (w/w) food-grade ?-carotene in an oil bath nonisothermally at 149°C at 28% (w/w) moisture content. To determine the total (thermal plus mechanical) effects of extrusion on retention of trans-?-carotene, the same mixture was extruded at 30/50/70/90/110°C and 50/70/90/110/130°C (barrel temperatures feed to exit) at screw speeds of 200, 250, 300, and 400 rpm on two separate days with a dough moisture content 30% (w/w). The rate constant at 100°C, 3.56 x 10-4s-1, and activation energy, 18.82 kJ/gmol, obtained from the nonisothermal experiments were used to calculate trans-?-carotene retention due to thermal effects during extrusion. For both temperature profiles, total trans-?-carotene retention ranged from 58 - 97%. Thermal effects accounted for less than 5% of the loss, showing that mechanical effects were the predominant cause of trans-?-carotene degradation. A linear statistical model worked well for separate days of extrusion; however, an exponential model was more effective for combined days of extrusion. Overall, food-grade ?-carotene was more stable than that of pure trans-?-carotene.

Pulsed ultraviolet light (PUV), a non-thermal food processing technology, is reported to be able to inactivate enzymes and reduce allergen levels from peanut extracts. The objective of this study was to determine if PUV would reduce the allergen levels and allergenic potency of soy extracts. Soy extracts were treated with PUV at various times (2, 4 and 6 min), centrifuged, and analyzed by SDS-PAGE and an indirect ELISA for IgE binding or allergenic potency. Results showed that PUV treatment led to an increase in sample temperature/weight loss but a decrease in the levels of soy allergens (i.e., glycinin and ?-conglycinin) as shown in SDS-PAGE. Allergens were reduced probably through aggregation which increased with treatment time. IgE binding was reduced as well in the following order: 20%, 44% and 50% reductions in absorbance values at 2, 4, 6 min, respectively (the latter two were not significantly different (p < 0.05%) from each other). It was concluded that PUV was capable of reducing the allergenic potency of soy extracts, and that the optimal PUV treatment time was 4 min. Clinical data is still needed before PUV can find an application in the development of less allergenic soybean beverages and products.

A process comprising of extraction, fermentation, separation and decolorization for the production of high fructose syrups and/or ethanol from dates' extract was developed. In this paper, selective fermentation of the glucose component in dates' extract by Saccharomyces cerevisiae was employed to tailor the composition of the final product (fructose- or ethanol-rich). Over 90% of dates’ sugar was extracted by water. The fermentation experiments were conducted at 30 °C and 120 rpm. The commonly marketed 55% fructose syrup was obtained at two operating conditions, i.e., low (<50%) and high (>92%) sugar conversions. Maximum fructose concentrations (77.2-78.2%) were obtained at moderately high sugar conversions (74-82%). Decolorization by activated carbon for the fructose-rich syrup resulted in 87% of color removal. Preliminary economic analysis revealed the viability of this process.

The effects of liquid-solid ratio, acetic acid concentration and extraction time on the yield of acid-soluble collagen(ASC) from the swim bladders of grass carp were optimized by statistical analysis using response surface methodology. The response surface methodology (RSM) was used to optimize the yield of ASC by implementing the Box-Wilson design. Statistical analysis of the results showed that the linear and quadric terms of these three variables had significant effects. However, no interactions between the three variables were found to contribute to the response at a significant level. The optimal conditions for higher yield of ASC were a liquid-solid ratio of 17.85, an acetic-acid concentration of 0.54 M and a time of 34 h. Under these conditions, the model predicted an ASC yield of 8.39%. Verification of the optimization showed that an ASC yield of 8.21±0.15% was observed under the optimal conditions. The experimental values agreed with the predicted values, using analysis of variance, indicating an excellent fit of the model used and the success of response surface methodology for modeling extraction of ASC from the swim bladders of grass carp.

Cassava root is an important staple food in tropical areas, where the cultivation of wheat is scarce. The transformation of cassava by conventional and established methods; manufacturing it into flour, add value and making it non perishable. The goals of the study were to evaluate the approximate composition and rheological properties of cassava flours and a ready to bake cake mix elaborated from composite flour [wheat: cassava(70:30)]. Cassava flour elaborated from the edible portion of root sweet clones was used to obtain the ready to bake cake mix. The results demonstrated that cassava flour shows a non Newtonian pseudoplastic behavior that is typical starchy flour characteristic. Also the amylographic profiles were similar in both types of flour. Also, the cake mix shows a Farinographic Type I curve. The texture profile of the composite flour cake had shown less firmness and chewiness but more cohesiveness, and elasticity than the 100 percent wheat flour cake. The composite flour cake was accepted as well as the 100 percent wheat flour cake by judge scores.

Ten semi-theoretical and empirical models were fitted to the experimental data to evaluate and select the best model for thin-layer drying of pomegranate arils. Experiments were conducted at six temperature levels of 45, 50, 55, 60, 65 and 70 °C and three levels of air velocity (0.5, 1 and 1.5 m/s). Microwave pretreatments were used for samples and the results were compared to those of control (no pretreatments). Regression analysis of mathematical models showed that the Midili model fitted best to the measured data. However, regarding R2 and MSE criteria, neural network modeling yielded a better prediction of pomegranate arils moisture ratio during drying of arils compared to all the mathematical models studied.

The rheological properties of two types of Persian honeys (Thyme and Shahjahan) were studied over temperature and water content of 10-30°C and 16.8-17.2%, respectively. At these conditions, they exhibited a Newtonian behavior for shear rate in range of 0-100 and apparent viscosity in range of 6.7 and 150 Pa.s. The activation energy, glass transition temperature and glass viscosity of Thyme and Shahjahan honeys were (104.5 and 109.7 kJ/mol), (225.6 and 228.2K), and (1.68 x 1011 and 1.48 x 1011 Pa.s), respectively. The Williams-Landel-Ferry (WLF) and Arrhenius Models used to check the dependency of viscosity and temperature data. The results showed that Thyme and Shahjahan honeys were fitted with WLF much better than Arrhenius model. However, the viscosity and water content data did not match with exponential model of Zaitoun, and the viscosity decreased with water content due to its plasticizing effect.

Demand for low-energy food products has greatly increased in recent years due to the growing concerns over obesity related health problems. The aim of the work described in this short communication was to use a microfluidic T-junction device to prepare microporous calcium alginate gels by incorporating monodisperse air bubbles (177 ?m in diameter) which would both increase the volume to energy content ratio of the product and improve sample homogeneity. Homogeneous, 5mm-thick gel samples were successfully obtained and found to have a density of 365 kg/m3. The high gas content was confirmed by ultrasound reflectivity measurements. The mean pore diameter, determined by optical and SEM measurements, was 131?m with a standard deviation of 57?m.