Journal of Food Process Engineering
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THERMAL CONDUCTIVITY AND DIFFUSIVITY OF SHELLED CORN AND GRAIN ABSTRACT Increasing energy costs have stressed the importance of calculation of heat and mass transfer in a grain bulk in order to be able to optimize drying facilities. Therefore values for the thermal conductivity and diffusivity of grain and especially shelled corn were determined. The investigations were carried out for single kernels as well as for grain and corn in bulk. Thermal conductivity and diffusivity were found to be mainly dependent on moisture content. Regression analyses showed a good correlation between moisture content and thermal conductivity or diffusivity, respectively.
Journal of Food Process Engineering - Tập 4 Số 3 - Trang 137-153 - 1981
Physical Stability and Antimicrobial Activity of Encapsulated Cinnamaldehyde by Self‐Emulsifying Nanoemulsion Abstract In the present study, natural cinnamaldehyde was encapsulated in self‐emulsifying emulsion systems. After optimization, the stability of encapsulated cinnamaldehyde was evaluated by dynamic light‐scattering and electronic nose. The antimicrobial activity of cinnamaldehyde was investigated by minimum inhibition concentration and time‐kill assay. The results showed that pure cinnamaldehyde as oil phase could not form stable emulsion under different oil‐to‐surfactant ratio. Stable cinnamaldehyde nanoemulsions were achieved with the addition of medium‐chain triglyceride. With the exception of temperature, the obtained nanoemulsions were stable against pH and NaCl . Phase separation was observed after 12 days of storage under 37C. Encapsulation efficiency of cinnamaldehyde in nanoemulsions was maintained around 80% within 1 week. Radar plots from electronic nose indicated that encapsulation could slow the release of cinnamaldehyde from nanoemulsion. Hence, the antimicrobial activity of cinnamaldehyde encapsulated in nanoemulsion could provide a long‐term inhibition on the bacterial growth of E scherichia coli compared with pure cinnamaldehyde. Practical Applications The applications of natural essential oils with their excellent antibacterial activities, such as cinnamon essential oils, as a food additive and green preservative are limited in the food systems, due to their highly instability against environmental conditions including temperature, light, air and others. The emulsification technique has been successfully utilized to overcome this drawback. However, it is known that emulsions with essential oils as oil phase will be highly unstable due to O stwald ripening. Although the evaluation of the stability and bioactivities of encapsulated essential oil is an important and critical issue during the practical application, hence, studies of the physical properties such as environmental stability, volatility and antibacterial activity can explore the ideal formulation and applications of natural essential oils.
Journal of Food Process Engineering - Tập 39 Số 5 - Trang 462-471 - 2016
Antioxidant activities of sunflower protein hydrolysates treated with dual‐frequency ultrasonic: Optimization study Abstract In this study, ultrasound pretreatments of sunflower‐meal protein (SMP) to yield high antioxidant capacity from its hydrolysates by response surface methodology were optimized. Optimization of experimental conditions was achieved to examine the impact of temperature, solvent‐solid ratio and sonication time on antioxidant capacities of SMP hydrolysates with Box–Behnken's design. Quadratic models of DPPH‐scavenging activity (DPPHSA), hydroxyl‐radical scavenging activity (HRSA), and Cu2+ and Fe2+ chelating activity (Cu2+ ‐CA and Fe2+ ‐CA) were developed, and their coefficients observed from multiple‐regression analysis. ANOVA indicated that time was highly significant (p < .01) on all experimental responses. The best experimental point of DPPHSA, HRSA, Cu2+ ‐CA, and Fe2+ ‐CA was accessed at 42.50°C, 18.16 mL/g and 26.52 min and the predicted data for these responses were 52.09, 70.05, 50.85, and 43.35%, respectively. Outcome of verification experiment was reliable with predicted data for all responses. Additionally, DPPHSA, HRSA, Cu2+ ‐CA, and Fe2+ ‐CA of pretreated hydrolysate improved (p < .05) by 17.41, 20.00, 14.72, and 26.41%, respectively over nonsonicated hydrolysate. Amino acid content and hydrophobicity of SMP hydrolysate at the optimum sonication condition were analyzed. Analyses indicated that ultrasonication could facilitate the releasing/unfolding of hydrophobic amino acids from SMP over nonsonicated samples during enzymolysis with high antioxidative capacity. Practical applications Sonication pretreatment has been presented to have notable impacts on the antioxidant's capacities of protein hydrolysates. Sunflower‐meal protein is an abundant and low‐cost residue of oil industries, and is considered a potential bioactive peptides source, such as antioxidants. In this research, sonication pretreatment has been illustrated to be an effectual technique for the production of hydrolysates with antioxidant capacity from SMP. So, optimization of ultrasonication conditions is vital to examine the antioxidant capacities in SMP hydrolysates, which could be applied in large‐scale food system and future pharmaceutical activity research.
Journal of Food Process Engineering - Tập 42 Số 5 - 2019
Improving the flavor of microbone meal with Flavourzyme by response surface method Abstract To improve the flavor of microbone meal, Flavourzyme was adopted to hydrolyze the meal and the hydrolysis conditions were optimized with the response surface method. The ANOVA results showed that the degree of hydrolysis (DH) of the microbone meal was significantly (p < 0.05) influenced by the amount of enzyme and hydrolysis time. In addition, the bitter and umami tastes of the microbone meal were significantly (p < 0.05) influenced by hydrolysis time and amount of enzyme, respectively. The optimization results showed that the optimal hydrolysis conditions were a Flavourzyme amount of 10.36%, hydrolysis temperature of 59.60°C, hydrolysis time of 5.84 hr, and pH of 7.75. The corresponding DH, bitter, and umami taste of the hydrolysate were 4.11%, 0.80 cent, and 1.90 cent, respectively. Characteristic volatile flavor compounds of the hydrolysate indicated that the Flavourzyme hydrolysis increased the meaty flavor of the microbone meal. Practical applications The obvious fishy smell and less meaty taste limited the microbone meal being mainly used in feeds. To broaden the applications of microbone meal in other fields, the Flavourzyme was adopted to improve its flavor. The Flavourzyme hydrolysis conditions were optimized with response surface method. The obtained hydrolysis conditions will benefit not only future investigations of animal bone by‐products applications, but also bone meal related product development. We believe that our findings could be of interest to meat related research units and enterprises by virtue of providing an alternative flavor improvement processing for bone meal application.
Journal of Food Process Engineering - Tập 42 Số 4 - 2019
DIELECTRIC PROPERTIES OF SHRIMP RELATED TO MICROWAVE FREQUENCIES: FROM FROZEN TO COOKED STAGES ABSTRACT Dielectric properties of shrimp (Penaeus sp.) were measured at frequencies between 0.3 and 3 GHz from ‐25 to 70C by using a network analyzer. The relationship between dielectric properties and temperature was determined at 915 MHz and 2450 MHz. Below the freezing point, the dielectric constant (ɛ′) and dielectric loss factor (ɛ″) increased rapidly with increasing temperature as ratio of frozen water in shrimp was decreasing. Above the freezing point, the dielectric constant (ɛ′) decreased as frequency and temperature increased at both frequencies. The dielectric loss factor (ɛ″) did not change significantly with temperature. The relationships between penetration depth and temperature at both frequencies were evaluated from the experimental data.
Journal of Food Process Engineering - Tập 22 Số 6 - Trang 455-468 - 1999
CONTINUOUS PASTEURIZATION OF EGG YOLK: THERMOPHYSICAL PROPERTIES AND PROCESS SIMULATION ABSTRACT This article presents empirical correlations to predict the density, specific heat, thermal conductivity and rheological power–law parameters of liquid egg yolk over a temperature range compatible with its industrial thermal processing (0–61C). Moreover, a mathematical model for a pasteurizer that takes into account the spatial variation of the overall heat transfer coefficient throughout the plate heat exchanger is presented, as are two of its simplified forms. The obtained correlations of thermophysical properties are applied for the simulation of the egg yolk pasteurization, and the obtained temperature profiles are used for evaluating the extent of thermal inactivation. A detailed simulation example shows that there is a considerable deviation between the designed level of heat treatment and that this is predicted through process simulation. It is shown that a reliable mathematical model, combined with specialized thermophysical property correlations, provide a more accurate design of the pasteurization equipment that ensures effective inactivation, while preserving nutritional and sensorial characteristics.
Journal of Food Process Engineering - Tập 28 Số 2 - Trang 181-203 - 2005
ELECTRICAL CONDUCTIVITIES of SELECTED SOLID FOODS DURING OHMIC HEATING<sup>1</sup> ABSTRACT Electrical conductivities of three vegetable and two meat samples were determined by subjecting them to a constant voltage power supply in a static ohmic heating device. Conductivities of vegetable samples were increased by soaking them in salt solutions, while soaking in water resulted in reduced conductivity due to leaching of electrolytes. Conductivities under ohmic heating conditions increased linearly with temperature. When field strengths were decreased, the conductivity‐temperature curve gradually became nonlinear, and under conventional heating conditions, a sharp transition was observed.
Journal of Food Process Engineering - Tập 14 Số 3 - Trang 221-236 - 1991
ELECTRICAL CONDUCTIVITY of APPLE and SOURCHERRY JUICE CONCENTRATES DURING OHMIC HEATING ABSTRACT Ohmic heating is based on the passage of electrical current through a food product that serves as an electrical resistance. In this study, apple and sourcherry concentrates having 20–60% soluble solids were ohmically heated by applying five different voltage gradients (20–60 V/cm). the electrical conductivity relations depending on temperature, voltage gradient and concentration were obtained. It was observed that the electrical conductivities of apple and sourcherry juices were significantly affected by temperature and concentration (P < 0.05). the ohmic heating system performance coefficients (SPCs) were defined by using the energies given to the system and taken up by the juice samples. the SPCs were in the range of 0.47–0.92. the unsteady‐state heat conduction equation for negligible internal resistance was solved with an ohmic heating generation term by the finite difference technique. the mathematical model results considering system performance coefficients were compared with experimental ones. the predictions of the mathematical model using obtained electrical conductivity equations were found to be very accurate.
Journal of Food Process Engineering - Tập 27 Số 3 - Trang 159-180 - 2004
ELECTRICAL CONDUCTIVITY of SELECTED JUICES: INFLUENCES of TEMPERATURE, SOLIDS CONTENT, APPLIED VOLTAGE, and PARTICLE SIZE<sup>1</sup> ABSTRACT A device was developed to determine the electrical conductivities of foods under ohmic or conventional heating conditions. Orange and tomato juices (serum and various solids contents) were tested in the device. the electrical conductivity of juices increased with temperature and decreased with solids content. the temperature dependence of conductivity was linear, both under conventional and ohmic heating. Experiments on suspensions of carrot juice solids, and polystyrene spheres in sodium phosphate solution showed an increase in electrical conductivity of the suspension with decreasing particle size.
Journal of Food Process Engineering - Tập 14 Số 4 - Trang 247-260 - 1991
Comparison between microwave‐cooking and steam‐cooking on starch properties and in vitro starch digestibility of cooked pigmented rice Abstract The influence of two types of cooking method, that is, steam‐cooking and microwave‐cooking, on the morphological structure, starch fractions, and starch digestibility of cooked Thai pigmented rice (three cultivars) was examined. The relationship between starch hydrolysis and change in X‐ray diffraction (XRD) pattern, including the change of crystallinity degree during in vitro digestion, was also investigated. The results indicated that the cooked rice morphological structure and starch hydrolysis rate during in vitro digestion was varied by the cooking method. All non‐waxy rice cultivars exhibited V h ‐type crystallinity, whereas, no crystalline peak was detected in the waxy rice cultivar. However, the XRD pattern and crystallinity degree of steam‐cooked rice were dramatically changed after simulated small intestinal digestion for 360 and 480 min when compared with microwave‐cooked rice. Moreover, steam‐cooked rice showed a significantly lower percentage of equilibrium starch hydrolysis than that of the microwave‐cooked rice. Practical applications Rice attributes and change of crystallinity in XRD pattern during in vitro digestion have found to correlate with rice starch digestibility, which varied depending on rice cooking methods. Steam‐cooking could enhance the degree of crystallinity during in vitro digestion, which would affect to retard rice starch digestion. This finding is interesting for the consumer on the selection of the optimized cooking process that promotes a healthier effect.
Journal of Food Process Engineering - Tập 42 Số 6 - 2019
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