International Journal of Food Engineering

Effect of Gluten Powder on the Quality of Fresh Spaghetti Made with Farina

Mahsa Majzoobi et al. — Thu, 09 Feb 2012 04:36:50 PST

The objective of this study was to improve the quality of fresh spaghetti made from ordinary wheat flour using gluten powder at different levels (0.0, 0.5, 1.5 and 3.0%, w/w, flour basis). The spaghetti dough was evaluated by a Brabender Farinograph. The results indicated that with increasing the gluten level, peak, stability time and consistency of the dough increased. The results of creep test (carried out using a Texture Analyser) showed that with increasing the gluten content, elasticity of the dough increased while its viscosity decreased. Increasing the gluten level reduced the cooking loss and increased the water absorption of the samples cooked in distilled or salted water (2% NaCl). The hardness and the color of the uncooked and cooked spaghettis improved with increasing the gluten content. The sample containing 3% gluten powder cooked in salted water received the highest score for its sensory attributes.

Effects of Fermentation on Nutritional and Functional Properties of Soybean, Maize, and Germinated Sorghum Composite Flour

Nicole Murekatete et al. — Thu, 09 Feb 2012 04:36:46 PST

Sorghum germination resulted in a substantial tannin loss (95.7 %). Proximate composition, titratable acidity, pasting properties, in vitro protein digestibility, and protein solubility were studied post fermentation (Saccharomyces Cerevisiae) of the blended soybean, maize, and germinated sorghum flours. The pH progressively decreased with fermentation time, while titratable acidity increased from 0.029 to 0.118 ml/ml. Crude protein content increased with fermentation (251.7-274.8 mg/g) as a result of a shift in the dry matter composition. In-vitro protein digestibility markedly increased (12 %) as a result of fermentation. Protein solubility curves were above 30% of which highest for both fermented (12 and 24 hours) and unfermented composite flours were at pH 12 (51.77-77.64%) and lowest at pH 4 (30.31-35.98%). SDS-PAGE showed that protein hydrolysis occurred during fermentation over 12 and 24 hours. Unfermented composite flour was potentially stable as food ingredient due to its pasting stability, but the fermented flour low viscosity potential was preferred in this study as more flour will be used during porridge making, hence giving a food with a high nutrient density.

Optimization of Enzymatic Hydrolysis Conditions for Preparation of Gingko Peptides from Ginkgo Nuts

Hanju Sun et al. — Tue, 31 Jan 2012 01:13:50 PST

Ginkgo nuts were used as raw material and peptides were prepared in turn with Neutral protease and Flavourzyme. In single-factor experiments of Neutral protease, conditions of temperature, pH, enzyme concentration and substrate concentration were optimized in term of degree of hydrolysis (DH). Based on the results of single-factor experiments, an orthogonal experiment (L9(3)4) was conducted to optimize the hydrolysis conditions of Neutral protease. The results showed that enzyme concentration, substrate concentration, reaction temperature and initial pH were the main variables that influenced DH. The highest DH was obtained when hydrolysis time, reaction temperature, initial pH, enzyme amount and substrate concentration were 4 h, 45 oC, 7.0, 1.8 mg/mL and 0.02 g/mL, respectively. Subsequently, the resulting solution was further hydrolyzed with Flavourzyme. Initial pH, temperature, time and enzyme concentration were optimized in term of DH. Finally, another orthogonal experiment (L9(3)4) was conducted to get the best enzymatic conditions of Flavourzyme, and enzyme concentration, initial pH, temperature and time were used as factors. The results showed that when Flavourzyme concentration, reaction temperature, initial pH and hydrolysis time were 9.0 mg/mL, 50 oC, 7.0 and 5 h, respectively, DH was the highest. The final degree of hydrolysis was 22.56%.

The Effect of Microwave Pasteurization on Some Physical and Chemical Characteristics of Milk

Afsaneh Dehghan et al. — Tue, 24 Jan 2012 02:54:54 PST

In this research, cow’s milk was pasteurized using microwave (MW) or HTST methods and their effects on some milk components were studied. The results showed no differences between some physico-chemical characteristics like protein, fat, acidity, and solubility percentages due to heat treatments with either MW or HTST and the control samples. The contents of six amino acids (aspartic acid, glycine, glutamic acid, histidine, arginine, and lysine in mg/L) and fatty acids (weight percentage) showed no significant differences using either MW or HTST pasteurization method. There were slight but insignificant differences in trans fatty acid and D-amino acid contents in the milk pasteurized with either MW or HTST method. SDS-PAGE and HPLC analysis of milk proteins did not reveal any differences between the pasteurization methods. It was finally concluded that MW heating is a good alternative to HTST pasteurization.

Modeling and Predicting the High Pressure Carbon Dioxide Inactivation of Microorganisms in Foods

Sencer Buzrul Assoc. Prof. Dr. — Sat, 21 Jan 2012 10:53:14 PST

Published high pressure carbon dioxide (HPCD) inactivation data of natural microflora in apple juice and Saccharomyces cerevisiae in distilled water were described by the Weibull model. The shape parameter of the Weibull model was assumed to be pressure and temperature independent and could be fixed to reduce the number of parameters of the model from two to one. The rate parameter of the reduced Weibull model can be described in terms of pressure and temperature by use of a second order polynomial function fulfilling a number of constraints. Integrated models (secondary model incorporated into the primary one) produced successful predictions of survival curves for both natural microflora in apple juice and Saccharomyces cerevisiae in distilled water within the interpolation region.

An Investigation on Physical Ageing of β-Lactoglobulin and Implications for Its Storage

Asgar Farahnaky Dr et al. — Sat, 21 Jan 2012 10:53:10 PST

Due to the importance of physical ageing in functional properties of the globular protein of β-lactoglobulin as the main protein of whey powder (the by product of cheese manufacturing industry) the possible occurrence of physical ageing in dry powder of β-lactoglobulin with moisture content of 15.9% was studied at different temperatures below and close to the glass transition.

Endothermic peaks that corresponded to relaxation enthalpy were observed for a β-lactoglobulin with 4 % moisture. Enthalpy and peak temperature increased on storage of β-lactoglobulin when it was held in the glassy state at different temperatures (20, 40, 60 º C). The general characteristics of the endothermic peaks were similar to those previously reported for synthetic polymers.

Modeling and Characterization of Blended Guava Pomace and Pulse Powder Based Rice Extrudates

Srikanth Tangirala et al. — Thu, 19 Jan 2012 18:11:12 PST

The purpose of the present work was to study the effect of guava pomace and pulse powder incorporation in to rice based extrudates on physical characteristics. Guava pomace collected after juice extraction was dried and milled. It was then added with pulse powder-rice flour blend at different combinations based on Central Composite Rotatable Design (CCRD). The independent variables were moisture content (17 – 21%), temperature (115 – 135°C), screw speed (230 – 270rpm), and varying proportion of rice, pulse and guava pomace. Higher feed moisture content resulted in extrudates with a higher density, lower expansion, higher water absorption index, lower water soluble index, and higher hardness. Higher barrel temperature resulted in reduced density, increased expansion, and water solubility index. Addition of guava pomace resulted in increase in water absorption index, hardness and decreased bulk density, expansion and water solubility index. The study suggested the guava pomace may be utilized up to the level of 10% to in Ready to Eat Snacks.

Evaluation of Boundary Conditions for CFD Simulation of Liquid Food Thermal Process in Glass Bottles

Pedro Esteves Duarte Augusto et al. — Wed, 18 Jan 2012 17:35:36 PST

The growing demand for safer and high-quality food products creates the need for better knowledge of the processes involved in food production. The computational fluid dynamics (CFD) have been widely used to better understand food thermal process, one of the safest and most frequently used methods for food preservation. However, no consistency in mathematical models has been observed, especially on the boundary conditions definition. The present study has evaluated four methodologies for the definition of boundary conditions for heating water in two commercial bottles: (M1) temperature profile of heating water (T∞) and convective heat transfer coefficient (h), (M2) T∞ as boundary condition for the outside package wall, (M3) T∞ as boundary condition for the outside heated liquid edge, and (M4) internal temperature profile (T=T(x,y,z,t)), previously measured in the inner package wall, as boundary condition for the outside heated liquid edge. Models that considered the measured value of h e T∞ as boundary condition showed good agreement with experimental values, compared by thermal history and sterilization value (F). The models that considered the temperature profile of the heating water or the inner package wall as boundary conditions, showed faster heating. By over-estimating the product heating rate, those models are not appropriated for thermal process modelling, as it compromises the safety and preservation of food products.

Using the Mitschka-Briggs-Steffe Method for Evaluation of Cactus Pear Concentrated Pulps Rheological Behavior

Pedro Esteves Duarte Augusto et al. — Wed, 18 Jan 2012 17:35:34 PST

The rheological characterization of food is important for efficient product and process design. Although its importance in semi-arid regions, there are only a few studies regarding the rheological properties of cactus pear products in the literature. The present work has used the Mitschka-Briggs-Steffe method for evaluation of the rheological behavior of cactus pear concentrated pulps. The pulps have shown pseudoplastic behavior. The flow behavior index (n) shows a constant value in the evaluated conditions, and its average value was considered in the evaluated temperature and concentration range. The consistency index (k) has shown dependency of concentration and temperature, being well modeled by a modified Arrhenius equation. Thus, the rheological parameters of cactus pear concentrated pulps can be obtained using a single equation, related with temperature, concentration and shear rate. The obtained data are potentially useful for future studies on product development, food properties and process design.

Mathematical Modelling of the Heat Transfer and Microbial Inactivation During a Meat Pet Food Sterilization in Retortable Pouches

Frampton Franklin Santana et al. — Wed, 18 Jan 2012 17:35:32 PST

Thermal process is still the most used and safer method for food preservation. Although the mathematical modelling of heat transfer has been used for thermal process evaluation, microbial validation is rarely carried out, and the evaluation of retortable stand up pouch processes were not studied. The present work employed a finite elements analysis model (FEA) for the evaluation of a conductive meat pet food process sterilization in stand up retortable pouches. The results obtained by the model showed good agreement with the experimental values, for both temperature histories and microbial inactivation comparison. The results obtained demonstrate the utility of using mathematical models for describing the heat transfer and microbial inactivation in food thermal process, and reinforce that it can be a powerful tool in food process evaluation and design.

Functional Characteristics of Extruded Blends of Potato Flakes and Whey Protein Isolate

Mariya A. Dushkova et al. — Tue, 17 Jan 2012 06:12:12 PST

The purpose of the present study was to explore the effects of feed moisture and the addition of whey protein isolate on some physicochemical properties of the obtained extrudates from potato flakes. Extrudates were produced using a laboratory single-screw extruder. Conditions during extrusion were: screw speed - 200 rpm; compression ratio - 3:1; extruders temperature zones - 120, 150, 160 °C; diameter of the nozzle - 5 mm. With increasing of feed moisture content and protein level, there was a significant rise of density as well as lowering of expansion of extrudates. As the feed moisture content increased from 13 to 20 percent w.w. the water absorption index (WAI) increased and the water solubility index (WSI) decreased. The feed protein level increased the protein content and decreased WAI. A maximum of WSI was observed at feed moisture content 20 percent w.w. and protein level 18 percent w.w. The extrusion and the protein addition do not affect the equilibrium moisture of the potato flakes extrudates.

Numerical Simulation of Experimental Freezing Process of Ground Meat Cylinders

Nelson O. Moraga et al. — Tue, 17 Jan 2012 06:12:09 PST

The efficient prediction of freezing processes is important for the frozen food industry with the purpose of preserving food quality. A comparison is made between the finite difference and finite volume methods to predict the unsteady 2D temperature distribution for the freezing of three different ground meat cylinders, with variable convective boundary conditions. Experiments were carried out to measure the local heat transfer coefficients as a function of freezing time and location. Time-dependent air temperature conditions caused by thermostat action were included in the analysis. The meat thermophysical properties as density, specific heat, and thermal conductivity are assumed to vary non-linearly with temperature. The experimentally measured time-temperature data were compared with the simulation results obtained by both numerical methods. According to statistical test results (RE %), the finite volume method gave the best fit quality. The finite volume method is more accurate for simulating the freezing process, as well as estimating the freezing time of this product

Correlating the Data on the Mechanical Damage to Mung Bean Seeds under Impact Loading

Feizollah Shahbazi et al. — Thu, 12 Jan 2012 18:18:14 PST

Mechanical damage of seeds due to harvest, handling, and other processes is an important factor that affects the quality and quaintly of seeds. This study evaluated impact damage to the mung bean seeds with moisture contents of 9.54 to 25% wet basis and subject to impact velocities from 10 to 25 m/s using a laboratory impact damage assessment device. The results showed that impact velocity, moisture content, and the interaction effects of these two variables significantly influenced the percentage physical damage in mung ban seeds (p<0.01). Increasing the impact velocity from 10 to 25 m/s caused a significant (p < 0.05) increase in the mean values of damage from 0.53 to 31.78%. The mean values of physical damage decreased significantly (p < 0.05) by a factor about two (from 22.41 to 11.24%), with increase in the moisture content from 9.54 to 20%. However, by a higher increase in the moisture from 20 to 25%, the mean value of damage showed a non-significant increasing trend. There was an optimum moisture level of 20%, at which seed damage was minimized. An empirical model composed of seed moisture content and velocity of impact developed for accurately describing the percentage of physical damage to mung beans. It was found that the model has provided satisfactory results over the whole set of values for the dependent variable.

Gel Properties of Ribbonfish (Trichiurus haumela) Surimi Gels with Soybean Dietary Fiber Induced by High Pressure and Heating

Zhenzhu Cheng et al. — Thu, 12 Jan 2012 18:18:12 PST

The effect of soybean dietary fiber in the functional and mechanical properties of restructured products from ribbonfish induced by their different treatments was investigated. Different amount of soybean dietary fiber (0, 10, 20, 30, or 50g/kg) was added at the same time as ice water to maintain similar moisture level in all samples. Then the samples with the same level of soybean dietary fiber were treated by high pressure (300MPa, 10min, P), high pressure followed by cooking (300MPa for 10min, then 90 ℃ for 20min, PC), and cooking after setting (40 ℃ for 30min, then 90 ℃ for 20min, SC), respectively. Results obtained suggest that soybean dietary fiber increased the gel strength of sample gels regardless of the treatments, and improved the texture properties of gels induced by PC and SC with almost imperceptible effect on the whiteness. The presence of soybean dietary fiber in the surimi gels also resulted in the increase in myosin heavy chain (MHC) band intensity. For gels with the same level of soybean dietary fiber, the high pressure treatment only made them softer, more elastic, and more translucent, and they kept their native color, compared with the other two treatments. The gels induced by PC had a significant increase in gel strength compared to that treated by SC.

Mechanical Damage to Pinto Bean Seeds as Affected by Moisture Content, Impact Velocity and Seed Orientation

Feizollah Shahbazi et al. — Tue, 03 Jan 2012 23:42:51 PST

The objective of this experiment was evaluate of the impact damage to pinto bean seeds where seed moisture content (9.25, 12.51, 15.01, 17.52, 20.01% wet basis), impact velocity (5.5, 8, 10, 12.5 and 15m/s) and seed orientation (end and side) were independent variables. The study was conducted under laboratory conditions, using an impact damage assessment device. The results showed that impact velocity, moisture content and seed orientation significantly influenced the physical damages of pinto beans at 1% level. Increasing the impact velocity from 5.5 to 15m/s caused an increase in the mean values of damage from 0.39 to 37.30%. With increase the moisture content from 9.25 to 17.52%, the mean values of percentage of damaged beans decreased significantly from 41.24 to 4.27%. However, by a higher increase in the moisture from 17.52 to 20.01%, the mean values of physically damaged beans showed a nonsignificant increasing trend. There was an optimum moisture level of 17.52% at which seed damage was minimized. The relationship between the percent of physical damage with impact velocity and beans moisture content was expressed mathematically. It was found that the percentage damage to seeds was a quadratic function of moisture content and impact velocity. Impact to the end of the seeds (18.62%) produced the higher damage than side orientation (13.12%).

Optimization of Extraction of D-pinitol and Phenolics from Cultivated and Wild Types of Carob Pods Using Response Surface Methodology

Irfan Turhan — Thu, 29 Dec 2011 18:09:20 PST

The carob pod, an important fruit of the food industry in the production of concentrated syrup, is rich in potentially health-promoting phenolic compounds and sugars. Moreover, one of the important bioactive components of carob is D-pinitol, and it has some beneficial effects on human metabolism. The optimum conditions for extraction of D-pinitol and total phenolic compounds (TPC) from cultivated and wild types of carob pods were determined using response surface methodology (RSM). The Box-Behnken Design (BBD) was used to investigate the effects of three independent variables; extraction temperature (ºC), dilution rate (w/v), and extraction time (h) on the response, D-pinitol and the total phenolic compounds. The optimum extraction conditions obtained using the response optimizer were an extraction temperature of 80ºC, a dilution rate of 1:4, and an extraction time of 2h. Under the mentioned above conditions, the maximum D-pinitol and TPC concentrations were 9.67 g/L and 5916.55 mg/L in wild carob pod extract, respectively.

Optimized Neural Network for Instant Coffee Classification through an Electronic Nose

Evandro Bona et al. — Fri, 23 Dec 2011 10:50:30 PST

Flavor is one of the most important features of food, especially of coffee. The evaluation of this sensory feature is complex yet indispensable in quality control of instant coffees. In this work, an artificial neural network (ANN) was developed for instant coffee classification based on an electronic nose (EN) aroma profile. To this purpose, a hybrid algorithm was developed, containing: bootstrap resample methodology; factorial design and sequential simplex optimization to tune network parameters; an ensemble multilayer perceptron (MLP) trained with backpropagation for coffee classification; and causal index procedure for knowledge extraction from the trained ANN. The produced neural network classifier correctly recognizes 100% of coffees studied. Furthermore, the causal index employment allowed inference of some rules on how the coffees were separated according to the sensors available in EN. The results indicate that the applied methodology is a promising tool for instant coffee quality control.

Performance of Artificial Neural Network for Predicting Fermentation Characteristics in Biosurfactant Production by Bacillus subtilis ATCC 6633 using Sugar Cane Molasses

Yousef Rahimi Kashkouli et al. — Tue, 13 Dec 2011 02:12:39 PST

Artificial neural network (ANN) was successfully applied to model fermentation parameters for biosurfactant production by Bacillus subtilis ATCC 6633 using sugar cane molasses. Cell growth and biosurfactant production were monitored along the surface activity of the cell-free broth. Response surface methodology (RSM) as a formal statistical model building system was used for the ANN development. The network predicted biosurfactant concentration was 0.381 g/l which showed almost no differences with the relevant experimental value which obtained according to the RSM arrangement. Furthermore, the ANN surface tension reduction was 30.48 mN/m, which was within 3.24% of the experimental value. Comparisons between RSM and the ANN showed preference of using ANN as complementary to RSM and not as a replacement to it.

Low Temperature Drying With Air Dehumidified by Zeolite for Food Products: Energy Efficiency Aspect Analysis

Mohamad Djaeni et al. — Fri, 09 Dec 2011 19:44:22 PST

Developments in low temperature drying of food products are still an interesting issue; especially with respect to the energy efficiency. This research studies the energy efficiency that can be achieved by a dryer using air which is dehumidified by zeolite. Experimental results are fitted to a dynamic model to find important variables for the drying operation. The results show that ambient air temperature as well as the ratio between air flow for drying and air flow for regeneration, affect the energy efficiency significantly. Relative humidity of used air, and shift time have a minor effect on the dryer performance. From the total work, it can be noted that the dryer efficiency operated at 50-60°C achieves 75 percent, which is attractive for drying of food products.

Adsorption Isotherms for Red Onion Slices Using Empirical and Neural Network Models

Hamid Reza Gazor et al. — Tue, 06 Dec 2011 02:22:44 PST

Moisture sorption isotherms of red onion slices were determined at 30, 40, 50, and 60°C using the standard gravimetric static method over a range of relative humidity from 0.11 to 0.83. The experimental sorption curves were fitted by seven empirical equations: modified Henderson, modified Chung–Pfost, modified Halsey, modified Oswin, modified Smith, modified BET, and GAB. Also three types of Artificial neural network models: linear, multilayer perceptron, and radial basis function were tested and developed to predict the equilibrium moisture content of onion slices and the selected models were trained by using related algorithms. The modified Oswin model was found acceptable for predicting adsorption moisture isotherms and fitting to the experimental data, based on the coefficient of determination (R²= 0.991), mean relative percent error (MRE=15.019), and standard error of estimation (SEE=1.371). Besides, multilayer perceptron model with four layers (2: 17: 14: 1) was selected as the best artificial neural network for estimation of onion slices’ equilibrium moisture content by considering R²= 0.993 and good performance. The net isosteric heat of adsorption of moisture was determined by applying the Clausius–Clapeyron equation to the sorption isotherms at different temperatures. The net isosteric heat of adsorption of red onion slices varied between 1.46 and 4.96 kJ/mol at moisture content varying between 2% and 52% (d.b.).