The Experts below are selected from a list of 3684 Experts worldwide ranked by ideXlab platform
Hong-wei Xiao - One of the best experts on this subject based on the ideXlab platform.
-
Effect of high-humidity hot Air Impingement blanching and pulsed vacuum drying on phytochemicals content, antioxidant capacity, rehydration kinetics and ultrastructure of Thompson seedless grape
Drying Technology, 2020Co-Authors: Jun Wang, Xiaoming Fang, Hong-wei Xiao, A.s. Mujumdar, Sriram K. Vidyarthi, Long XieAbstract:A new pretreatment method using high humidity hot Air Impingement blanching (HHAIB) followed by pulsed vacuum drying (PVD) was employed for Thompson seedless drying. The effect of this dehydration ...
-
Effects of different drying methods on drying kinetics, physicochemical properties, microstructure, and energy consumption of potato (Solanum tuberosum L.) cubes
Drying Technology, 2020Co-Authors: Hui Wang, Zi-liang Liu, Sriram K. Vidyarthi, Yanhong Liu, Qing-hui Wang, Lei Gao, Qing Wei, Hong-wei XiaoAbstract:In current work, Air Impingement drying (AID), infrared-assisted hot Air-drying (IR-HAD), and hot Air drying based on temperature and humidity control (TH-HAD) drying technologies were employed to ...
-
high humidity hot Air Impingement blanching hhaib efficiently inactivates enzymes enhances extraction of phytochemicals and mitigates brown actions of chili pepper
Food Control, 2020Co-Authors: Hui Wang, Xiaoming Fang, Magdalena Zielińska, Wei Wu, Arun S. Mujumdar, Qian Zhang, Hong-wei XiaoAbstract:Abstract In current work, high-humidity hot Air Impingement blanching (HHAIB) was employed to inactivate peroxidase enzymes (POD) of chili pepper under three independent variables, namely blanching temperature (105, 110, and 115 °C), relative humidity (20%, 30%, and 40%), and blanching time (30, 60, and 90 s). Response surface methodology (RSM) was used to optimize the blanching conditions based on product POD residual activity and browning index. Results indicated that blanching temperature of 110 °C, relative humidity of 40% and blanching time of 38 s were the optimum blanching conditions, which resulted in the minimum POD residual activity (0.52%) and browning index difference (7.09). Validation test showed that the predicted data had good agreement with the experimental data. Results also indicated that compared with the non-blanched samples, the extraction content of ascorbic acid and red pigment from blanched pepper under optimal blanching conditions increased by 42.85% and 8.20%, respectively. Ultrastructural observations explained why moderate blanching can promote the extraction of phytochemicals. The findings in current work indicate that HHAIB can efficiently inactivate enzymes, enhance extraction of phytochemicals and at the meantime mitigate brown actions under optimal conditions.
-
Hot Air Impingement drying kinetics and quality attributes of orange peel
Journal of Food Processing and Preservation, 2019Co-Authors: Li-zhen Deng, Arun S. Mujumdar, Qian Zhang, Zhian Zheng, Wen-xia Yang, Hong-wei XiaoAbstract:In the recent work, hot Air Impingement drying was employed to orange peel processing under different temperatures and its effects on drying kinetics and quality attributes of the orange peel were investigated. Results showed that the drying time of peels decreased from 150 to 75 min as the temperature increased from 50 to 70°C, and the Weibull model precisely described the drying kinetics. The total polyphenols, flavonoids, ascorbic acid (AA), and antioxidant capacity markedly decreased after drying. The total polyphenols, flavonoids, ascorbic acid (AA), and antioxidant capacity of the orange peel markedly decreased after drying. In the case of total flavonoids and color, no significant effect (p > .05) was observed for different drying temperatures. While, the water retention capacity decreased with increasing of drying temperature. The findings contribute to a better understanding of Air Impingement drying characteristics of orange peel and help to optimize drying conditions for the maximum preservation of its phytochemicals and antioxidant capacity. PRACTICAL APPLICATIONS: As the primary by‐product of orange juice processing, orange peel is an excellent source of physiochemical compounds, which take an important role in health promoting. However, it is often discarded as garbage as it rots easily and hard to preserve due to its high moisture content. Drying is an essential step for the preservation and utilization of peel waste. Several drying techniques have been applied for the dehydration of citrus by‐products, such as sun drying, hot Air drying, freezing drying, etc. But they are difficult to achieve the rapid and reliable industrial processing of peel waste. The findings of this work indicate that hot Air Impingement drying is a promising drying technique for orange peel and drying temperature of 65°C allowed the best preservation of polyphenols and ascorbic acid as well as the antioxidant capacity.
-
Prediction of energy and exergy of mushroom slices drying in hot Air Impingement dryer by artificial neural network
Drying Technology, 2019Co-Authors: Zi-liang Liu, Hui Wang, Zhenjiang Gao, Junwen Bai, Shu-xi Wang, Jian-sheng Meng, Hong-wei XiaoAbstract:In current work, the energy and exergy analysis of hot Air Impingement drying mushroom slices was conducted under different Air temperature (55, 60, 65, 70, and 75 °C), Air velocity (3, 6, 9, and 12 m/s), and sample thickness (6, 9, and 12 mm) by the first and second law of thermodynamics. The statistical analysis results indicated that the effect of Air velocity and temperature on the energy and exergy was more important than the sample thickness on it. The energy utilization and energy utilization ratio were in the range of 0.067–0.859 kJ/s and 0.087–0.34, respectively. The exergy loss and exergy efficiency was varied from 0.045–0.571 kJ/s and 0.315–0.879, respectively. Besides, the artificial neural network (ANN) was employed to predict the energy and exergy parameters. The modeling results revealed that the ANN models with arranged training algorithms and transfer function could be utilized to predict the performance of hot Air Impingement drying system with satisfactory accuracy.
Zhenjiang Gao - One of the best experts on this subject based on the ideXlab platform.
-
Prediction of energy and exergy of mushroom slices drying in hot Air Impingement dryer by artificial neural network
Drying Technology, 2019Co-Authors: Zi-liang Liu, Hui Wang, Zhenjiang Gao, Junwen Bai, Shu-xi Wang, Jian-sheng Meng, Hong-wei XiaoAbstract:In current work, the energy and exergy analysis of hot Air Impingement drying mushroom slices was conducted under different Air temperature (55, 60, 65, 70, and 75 °C), Air velocity (3, 6, 9, and 12 m/s), and sample thickness (6, 9, and 12 mm) by the first and second law of thermodynamics. The statistical analysis results indicated that the effect of Air velocity and temperature on the energy and exergy was more important than the sample thickness on it. The energy utilization and energy utilization ratio were in the range of 0.067–0.859 kJ/s and 0.087–0.34, respectively. The exergy loss and exergy efficiency was varied from 0.045–0.571 kJ/s and 0.315–0.879, respectively. Besides, the artificial neural network (ANN) was employed to predict the energy and exergy parameters. The modeling results revealed that the ANN models with arranged training algorithms and transfer function could be utilized to predict the performance of hot Air Impingement drying system with satisfactory accuracy.
-
high humidity hot Air Impingement blanching hhaib enhances drying quality of apricots by inactivating the enzymes reducing drying time and altering cellular structure
Food Control, 2019Co-Authors: Li-zhen Deng, Zhian Zheng, Zhenjiang Gao, A.s. Mujumdar, Jinhong Zhao, Zhongli Pan, Hong-wei XiaoAbstract:Abstract Effects of high-humidity hot Air Impingement blanching (HHAIB) on peroxidase (POD) and polyphenol oxidase (PPO) activities, ultrastructure, water distribution, drying time, and key quality attributes of apricots were investigated under Air temperature of 110 °C and relative humidity of 35%–40% for various exposure times ranging from 30 to 150 s. HHAIB inactivated POD and PPO fully within 120 s, induced alteration of cellular structure and resulted in redistribution of water among the cell compartments. Compared to the untreated sample, HHAIB reduced the drying time by 19.36%–36.40%. Optimal pretreatment (120 s) resulted in dried apricots with higher total phenolics (TP) and total carotenoids (TC) along with enhanced antioxidant capacity, as well as better color. The TP, TC and antioxidant capacity were observed to be significantly correlated to POD and PPO activities, water distribution and drying time. Over-blanching (150 s) prolonged drying time, induced higher degradation of TP, TC, antioxidant capacity and color compared to dried products pre-blanched for 120 s. Hence, proper HHAIB pretreatment enhances drying process and improves the quality attributes of dried apricots.
-
effects of high humidity hot Air Impingement blanching hhaib pretreatment on the change of antioxidant capacity the degradation kinetics of red pigment ascorbic acid in dehydrated red peppers during storage
Food Chemistry, 2018Co-Authors: Jun Wang, Xuhai Yang, Xiaoming Fang, Arun S. Mujumdar, Qian Zhang, Zhian Zheng, Zhenjiang Gao, Hong-wei XiaoAbstract:Abstract Effect of high-humidity hot Air Impingement blanching on photochemical degradation kinetics (red pigments and ascorbic acid) and antioxidant capacity changes (2,2-diphenyl-1-picrylhydracyl, DPPH and total antioxidant capacity) of red pepper during 6-month storage at ambient temperature in dark was investigated. Ultrastructure of raw and blanched samples was also observed using a transmission electron microscope (TEM). Blanching followed by drying resulted in 63–85% and 33–59% reduction in red pigment and ascorbic acid content, respectively. The antioxidant capacity of samples was found to increase after drying. After 6-month storage, further breakdown of red pigment and ascorbic acid was observed. The red pigment degradation followed the first-order reaction kinetics; untreated samples displayed the most red pigment loss, while the Weibull model described well the ascorbic acid degradation kinetics. Ultrastructure observations explained why over-blanching can cause serious phytochemical degradation. The current findings indicate proper blanching pretreatment prevents phytochemicals degradation of dried pepper during storage.
-
High humidity hot Air Impingement blanching (HHAIB) enhances drying rate and softens texture of apricot via cell wall pectin polysaccharides degradation and ultrastructure modification.
Food chemistry, 2018Co-Authors: Li-zhen Deng, Xuhai Yang, Qian Zhang, Jun Wang, Zhian Zheng, Zhenjiang Gao, A.s. Mujumdar, Hong-wei XiaoAbstract:Abstract The effects of high humidity hot Air Impingement blanching (HHAIB) over a range of application times (30, 60, 90, and 120 s) on drying characteristics, hardness, cell wall pectin fractions contents and nanostructure, as well ultrastructure of apricot were investigated. Results showed that HHAIB reduced drying time and decreased the hardness of apricot by 20.7%–34.5% and 46.57%–71.89%, respectively. The water-soluble pectin (WSP) contents increased after blanching, while the contents of chelate-soluble pectin (CSP) and sodium-carbonate-soluble pectin (NSP) decreased significantly (P
-
thin layer Air Impingement drying enhances drying rate of american ginseng panax quinquefolium l slices with quality attributes considered
Food and Bioproducts Processing, 2015Co-Authors: Hong-wei Xiao, Junwen Bai, Long Xie, Dawen Sun, Zhenjiang GaoAbstract:Abstract The effect of drying temperature, Air velocity, and sample thickness on thin-layer Air Impingement drying characteristics and quality of American ginseng slices in terms of color parameters ( L *, a *, and b *), ginsenosides content (Rg 1 , Re, and Rb 1 ), rehydration ratio (RR), and microstructure were investigated. Results indicated that thin-layer Air Impingement drying enhances drying rate dramatically compared with other drying methods, and that the drying time was principally affected by drying temperature followed by sample thickness and Air velocity. Quality evaluation revealed that both drying temperature and sample thickness had significant effects on the change of color, whereas, Air velocity did not have any significant effect. It was also observed that ginsenosides Rg 1 and Re decreased with increasing drying temperature. Drying temperature, Air velocity, and sample thickness had significant negative effects on the RR of dried slices. Microstructure comparison illustrated that starch gelatinization occurred at a drying temperature of 65 °C and that a gel layer was formed on the sample's surface. On the basis of the drying time and quality of the dried products, the most favorable drying conditions were recommended.
Arun S. Mujumdar - One of the best experts on this subject based on the ideXlab platform.
-
high humidity hot Air Impingement blanching hhaib efficiently inactivates enzymes enhances extraction of phytochemicals and mitigates brown actions of chili pepper
Food Control, 2020Co-Authors: Hui Wang, Xiaoming Fang, Magdalena Zielińska, Wei Wu, Arun S. Mujumdar, Qian Zhang, Hong-wei XiaoAbstract:Abstract In current work, high-humidity hot Air Impingement blanching (HHAIB) was employed to inactivate peroxidase enzymes (POD) of chili pepper under three independent variables, namely blanching temperature (105, 110, and 115 °C), relative humidity (20%, 30%, and 40%), and blanching time (30, 60, and 90 s). Response surface methodology (RSM) was used to optimize the blanching conditions based on product POD residual activity and browning index. Results indicated that blanching temperature of 110 °C, relative humidity of 40% and blanching time of 38 s were the optimum blanching conditions, which resulted in the minimum POD residual activity (0.52%) and browning index difference (7.09). Validation test showed that the predicted data had good agreement with the experimental data. Results also indicated that compared with the non-blanched samples, the extraction content of ascorbic acid and red pigment from blanched pepper under optimal blanching conditions increased by 42.85% and 8.20%, respectively. Ultrastructural observations explained why moderate blanching can promote the extraction of phytochemicals. The findings in current work indicate that HHAIB can efficiently inactivate enzymes, enhance extraction of phytochemicals and at the meantime mitigate brown actions under optimal conditions.
-
Hot Air Impingement drying kinetics and quality attributes of orange peel
Journal of Food Processing and Preservation, 2019Co-Authors: Li-zhen Deng, Arun S. Mujumdar, Qian Zhang, Zhian Zheng, Wen-xia Yang, Hong-wei XiaoAbstract:In the recent work, hot Air Impingement drying was employed to orange peel processing under different temperatures and its effects on drying kinetics and quality attributes of the orange peel were investigated. Results showed that the drying time of peels decreased from 150 to 75 min as the temperature increased from 50 to 70°C, and the Weibull model precisely described the drying kinetics. The total polyphenols, flavonoids, ascorbic acid (AA), and antioxidant capacity markedly decreased after drying. The total polyphenols, flavonoids, ascorbic acid (AA), and antioxidant capacity of the orange peel markedly decreased after drying. In the case of total flavonoids and color, no significant effect (p > .05) was observed for different drying temperatures. While, the water retention capacity decreased with increasing of drying temperature. The findings contribute to a better understanding of Air Impingement drying characteristics of orange peel and help to optimize drying conditions for the maximum preservation of its phytochemicals and antioxidant capacity. PRACTICAL APPLICATIONS: As the primary by‐product of orange juice processing, orange peel is an excellent source of physiochemical compounds, which take an important role in health promoting. However, it is often discarded as garbage as it rots easily and hard to preserve due to its high moisture content. Drying is an essential step for the preservation and utilization of peel waste. Several drying techniques have been applied for the dehydration of citrus by‐products, such as sun drying, hot Air drying, freezing drying, etc. But they are difficult to achieve the rapid and reliable industrial processing of peel waste. The findings of this work indicate that hot Air Impingement drying is a promising drying technique for orange peel and drying temperature of 65°C allowed the best preservation of polyphenols and ascorbic acid as well as the antioxidant capacity.
-
experimental and simulation studies of heat transfer in high humidity hot Air Impingement blanching hhaib of carrot
Food and Bioproducts Processing, 2019Co-Authors: Xianlong Yu, Arun S. Mujumdar, Jun Wang, Zhian Zheng, Li-zhen Deng, Haoyu Ju, Hong-wei XiaoAbstract:Abstract A mathematical model was presented to characterise heat transfer in high-humidity hot Air Impingement blanching (HHAIB) of cuboid carrots. The model accounts for condensation heat transfer and predicts the sample’s core temperature evolution with time. The simulation was performed at different relative humidity of 20%, 40%, 60%, 80% with constant temperature of 383 K. Results showed that the heat transfer process of HHAIB is divided into two stages based on vapor–liquid phase transition, namely a condensing heat transfer segment and a non-condensing heat transfer segment. In the initial stage of HHAIB, a comprehensive and intense condensation occurred on the sample surface leading to high heat transfer coefficient and greatly enhancing heat transfer, but at the same time creating a huge temperature gradient in the sample. The relative humidity of 40%–60% at 383 K could not only enhance the heat transfer rate but also improve the homogeneity of temperature distribution in the sample. Simulated core temperatures were compared with experimental measurements, showing good agreement with a coefficient of determination R2 of 0.991. The findings of current work provide theoretical basis to better design and control of the process conditions of HHAIB as it elucidates the heat transfer characteristic taking account condensation phenomenon and illustrates the temperature distribution and evolution profiles.
-
effects of high humidity hot Air Impingement blanching hhaib pretreatment on the change of antioxidant capacity the degradation kinetics of red pigment ascorbic acid in dehydrated red peppers during storage
Food Chemistry, 2018Co-Authors: Jun Wang, Xuhai Yang, Xiaoming Fang, Arun S. Mujumdar, Qian Zhang, Zhian Zheng, Zhenjiang Gao, Hong-wei XiaoAbstract:Abstract Effect of high-humidity hot Air Impingement blanching on photochemical degradation kinetics (red pigments and ascorbic acid) and antioxidant capacity changes (2,2-diphenyl-1-picrylhydracyl, DPPH and total antioxidant capacity) of red pepper during 6-month storage at ambient temperature in dark was investigated. Ultrastructure of raw and blanched samples was also observed using a transmission electron microscope (TEM). Blanching followed by drying resulted in 63–85% and 33–59% reduction in red pigment and ascorbic acid content, respectively. The antioxidant capacity of samples was found to increase after drying. After 6-month storage, further breakdown of red pigment and ascorbic acid was observed. The red pigment degradation followed the first-order reaction kinetics; untreated samples displayed the most red pigment loss, while the Weibull model described well the ascorbic acid degradation kinetics. Ultrastructure observations explained why over-blanching can cause serious phytochemical degradation. The current findings indicate proper blanching pretreatment prevents phytochemicals degradation of dried pepper during storage.
-
high humidity hot Air Impingement blanching alters texture cell wall polysaccharides water status and distribution of seedless grape
Carbohydrate Polymers, 2018Co-Authors: Jun Wang, Hong-wei Xiao, Arun S. Mujumdar, Li-zhen Deng, G S V RaghavanAbstract:Abstract Blanching pretreatment plays an essential role in fruits and vegetables processing to obtain excellent final products. The purpose of current work was to characterise the texture, cell-wall polysaccharides and water distribution of grapes pre- and post- high-humidity hot Air Impingement blanching (HHAIB). The cell-wall pectins nanostructure, water status and distribution of samples were determined by atomic force microscopy (AFM), low field nuclear magnetic resonance (LF-NMR) and magnetic resonance image (MRI), respectively. Results revealed that blanching caused significant berry tissue softening which was accompanied by an increase of water-soluble pectin (WSP, from 39.57 to 57.44 g/100 g fresh weight) and a decrease of chelate-soluble pectin (CSP, from 79.34 to 53.78 g/100 g fresh weight) and sodium-carbonate-soluble pectin (NSP, from 364.23 to 187.64 g/100 g fresh weight) concentration. Obvious depolymerization and degradation was observed in cell-wall polysaccharides nanostructure in blanched berries. The length frequencies of WSP chains are mainly distributed in the range of 0.51–2.00 μm, while it was 1.01–2.00 μm for the CSP chains of blanched samples. LF-NMR transverse relaxation time and MRI analysis indicated that HHAIB treatment resulted in a water loss and migration from berry interior to surface tissue. The findings in present study provide a deeper understanding in tissue softening and moisture variation of blanched berries.
Rosana G. Moreira - One of the best experts on this subject based on the ideXlab platform.
-
Impingement drying of foods using hot Air and superheated steam
Journal of Food Engineering, 2001Co-Authors: Rosana G. MoreiraAbstract:Impingement drying is an old technology that has only recently been applied to food products. Tortilla and potato chips, pizza crust, pretzels, crackers, and cooks, for example, have been successfully cooked and baked in Air-Impingement ovens in the food industry. Granular products (coffee beans, cocoa beans, rice, nuts) dry faster and more uniformly when using Impingement dryers due to the pseudofluidized bed created by the high-velocity Air from the nozzles. Tortilla chips and potato chips have been Impingement dried using hot Air and superheated steam. At higher Air temperatures (above 130°C), tortilla chips dry faster when using superheated steam compared to hot Air (at the same conditions). Impingement drying with superheated steam can produce potato chips with less color deterioration and less nutritional losses (Vitamin-C) than drying with hot Air. Potato chips dry faster at high superheated steam temperature and high convective heat transfer coefficients.
-
Reduction of Oil in Tortilla Chips using Impingement Drying
LWT - Food Science and Technology, 1997Co-Authors: Javier Lujan-acosta, Rosana G. MoreiraAbstract:Tortilla pieces were prepared from nixtamalized masa flour and dried under impinging hot Air. The effect of different drying conditions on the drying rate, texture, shrinkage profile and microstructure was analysed. The results indicated that drying rate was mostly affected by the Air temperature; texture was crispier at higher Air temperatures; shrinkage of the piece was higher at lower convective heat transfer coefficient; and microstructure looked smoother at higher Air temperature. A process to produce low-fat tortilla chips with good flavor and texture using convection-oven baking, Air Impingement drying, and frying was suggested and validated.
-
Air Impingement drying of tortilla chips
Drying Technology, 1997Co-Authors: Javier Lujanacosta, Rosana G. Moreira, J SeyedyagoobiAbstract:ABSTRACT Tortilla pieces were prepared from nixtamalized masa flour, and dried under impinging hot Air. The effect of different drying conditions on the drying rate, texture, shrinkage profile and microstructure was analyzed. The results indicated that drying rate was mostly affected by the Air temperature; texture was crispier at higher Air temperatures: shrinkage of the piece was higher at lower convective heat transfer coeffieient; and microstructure looked smoother at higher Air temperature.
R. Paul Singh - One of the best experts on this subject based on the ideXlab platform.
-
Air-Impingement cooling of boiled eggs: Analysis of flow visualization and heat transfer
Journal of Food Engineering, 2007Co-Authors: Ferruh Erdogdu, Maria Ferrua, Samrendra K. Singh, R. Paul SinghAbstract:Abstract Production of ready-to-eat boiled eggs is a rapidly expanding process. Cooling of the boiled eggs, before peeling, is therefore a significant part of the production. Use of water immersion for cooling purposes is traditional way to accomplish a faster cooling process. However, the utilization of water brings the waste water problem with itself, and there also might be a cross-contamination problem after a longer use. Since the Air-Impingement processes are to produce higher heat fluxes over the product surface, cooling of boiled eggs by a slot Air (24 °C) Impingement system ( H / D of 3-jet exit to object distance over hydraulic diameter of the jet, Reynolds number of ≈7000) was investigated in this study. Continuity, conservation of momentum and conservation of energy equations were solved using Fluent 6.0 (Lebanon, NH). In order to model the turbulent Air flow, the κ – e turbulence model was applied. The model results were validated by comparing them with the experimental flow (the particle image velocimetry-PIV data) and temperature data (obtained at different locations of the egg). Different cooling conditions (0 °C impinged Air and 0 °C water-for immersion type of cooling) were also simulated, and the results were compared with each other to show the effectiveness of the Air-Impingement systems. The results of this study showed the potential of Air-Impingement systems for an effective use in cooling of boiled eggs. However, it would also be valuable to show the effects of different Impingement parameters (e.g., H / D , d / D , different nozzle arrangements and effects of higher Reynolds numbers) to compare the results with different cooling systems (e.g., use of spray water).
-
Modeling the thawing of frozen foods using Air Impingement technology
International Journal of Refrigeration, 2006Co-Authors: Brent A. Anderson, R. Paul SinghAbstract:With the continual growth in the use of frozen foods both in retail and in food service, there is a need to develop improved thawing methods. Current methods are often undesirably slow (still Air) or are very expensive and cause uneven thawing (microwave). Air Impingement technology is one possible method to improve the thawing of frozen foods. The objectives of this research were to develop a two-dimensional model for Air Impingement thawing frozen foods and to verify the model experimentally. Frozen products were thawed using a laboratory Impingement system with a single Impingement jet. A simulated meat product (Tylose gel) was used as the test material. Thawing of a Tylose disk (12.7 cm diameter, 1.98 cm thickness) with Air at 6 °C without Impingement required more than 12 h, while thawing under a single Impingement jet took less than 3 h, over four times faster. Results from the finite difference model gave good agreement with experimental data. Moisture loss during thawing was typically over-predicted because moisture gain due to condensation was not modeled.
-
Effective heat transfer coefficient measurement during Air Impingement thawing using an inverse method
International Journal of Refrigeration, 2006Co-Authors: Brent A. Anderson, R. Paul SinghAbstract:Convective heat transfer coefficient is a critical parameter in analyzing heating systems. When Air Impingement technology is applied to the thawing of frozen foods, the resulting effective heat transfer coefficient becomes quite complicated. The Airflow from Impingement jets result in heat transfer coefficient that varies with position. In addition, transient thawing results in effective heat transfer coefficient that varies with time and surface temperature. Effective heat transfer coefficients as a function of position and surface temperature were determined using an inverse method for thawing from a single Impingement jet. Regularization parameters used in this inverse method were determined using simulated data. Effective heat transfer coefficients tended to increase with time as thawing progressed. Heat transfer coefficients decreased radially, but exhibited secondary maxima at radial distances approximately equal to the nozzle diameter. This inverse method enables estimation of heat transfer coefficient as a function of both time and position.
-
Air Impingement technology for food processing: visualization studies
LWT - Food Science and Technology, 2004Co-Authors: Arnab Sarkar, R. Paul SinghAbstract:Abstract Food processing systems using Air Impingement consist of jets of high-velocity Air (10–100 m/s) exiting from nozzles and impinging on a food product. The factors affecting efficiency of Impingement systems include the nozzle exit velocity, nozzle design, boundary layer characteristics on the surface of the product and the design of the Impingement equipment. In the present research, visualization studies were conducted to determine the importance and implication of these factors. Flow under the jets was visualized using planar flow visualization techniques for various nozzle diameters (D), lengths (L) and nozzle to plate spacings (H) for flow over flat surfaces and food products with single and double jets. Studies were conducted on the transition features, recirculation, confinement and boundary layer flow characteristics. Ideal range for the characteristic nondimensional ratio (H/D) was determined to be 6–8. The actual ratio will depend on the transition effect and the induction of turbulence in the jet wake, which depends on the Reynolds number (Re) based on nozzle exit conditions and the L/D ratio of the nozzle. Surface roughness affected the roughness Reynolds number (Rep) which in turn influenced the boundary layer characteristics.