Background:To predict the moisture ratio of Radix isatidis extract during drying.Methods:Artificial neural networks were designed using the MATLAB neural network toolbox to produce a moisture ratio prediction model of...Background:To predict the moisture ratio of Radix isatidis extract during drying.Methods:Artificial neural networks were designed using the MATLAB neural network toolbox to produce a moisture ratio prediction model of Radix isatidis extract during hot air drying and vacuum drying,where regression values and mean squared error were used as evaluation indexes to optimize the number of hidden layer nodes and determine the topological structure of artificial neural networks model.In addition,the drying curves for the different drying parameters were analyzed.Results:The optimal topological structure of the moisture ratio prediction model for hot air drying and vacuum drying of Radix isatidis extract were“4-9-1”and“5-9-1”respectively,and the regression values between the predicted value and the experimental value is close to 1.This indicates that it has a high prediction accuracy.The moisture ratio gradually decreases with an increase in the drying time,reducing the loading,initial moisture content,increasing the temperature,and pressure can shorten the drying time and improve the drying efficiency.Conclusion:Artificial neural networks technology has the advantages of rapid and accurate prediction,and can provide a theoretical basis and technical support for online prediction during the drying process of the extract.展开更多
The microwave coupled with hot air(MCHA)drying method was used in this test to dry hawthorn slices The effect of initial microwave power density level(6 W/g to 12 W/g),hot air temperature(55℃ to 70℃),and hot air vel...The microwave coupled with hot air(MCHA)drying method was used in this test to dry hawthorn slices The effect of initial microwave power density level(6 W/g to 12 W/g),hot air temperature(55℃ to 70℃),and hot air velocity(1 m/s to 3 m/s)on the quality attributes of rehydration ratio(Rf),organic acid(OA)and ascorbic acid(AA)of the dehydrated hawthorn slices was analyzed using a response surface methodology.An orthogonal rotatable central composite with three factors and at five levels was used to develop predictive regression models for the responses.The prediction mathematical model of Rf,OA and AA of the hawthorn slice was determined by analysis of variance.Factor and response variables as well as the prediction mathematical model,the optimal drying process of Rf,OA and AA of the hawthorn slice were determined by using the Design-Expert software.The comprehensive optimal conditions were as follows:initial microwave power density 12 W/g,hot air temperature 55℃ and hot air velocity 1.56 m/s.展开更多
Hot air temperature,hot air humidity,and hot wind speed were selected as independent variables of quadratic orthogonal rotation combination test design through single factor test.Drying time,energy consumption,chromat...Hot air temperature,hot air humidity,and hot wind speed were selected as independent variables of quadratic orthogonal rotation combination test design through single factor test.Drying time,energy consumption,chromatism value,luminosity value,hardness,rehydration ratio,and other indexes of the product were used as the response value of the test.Response surface methodology(RSM)was used to analyze the effects of independent variables on the quality of tiger nut(Cyperus esculentus L.),and the process parameters were combined and optimized.The results show that the suitable technological conditions for hot air drying of tiger nut are as follows:hot air temperature of 63.15°C,hot air humidity of 44.92%,hot air wind speed of 2.48 m/s.Under these conditions,the product has the advantages of the short drying cycle,low energy consumption,good color and luster,low hardness and good rehydration performance.The fatty acid composition and content of tiger nut oil were determined by gas chromatography.The fatty acid composition and content of tiger nut oil were compared with those of soybean oil,olive oil,rapeseed oil and sesame oil,the results show that among the saturated fatty acids in tiger nut oil,palm oil had the highest content of 11.172%,which was between soybean oil and olive oil.The main composition of unsaturated fatty acids in tiger nut oil is oleic acid,with a content of 77.605%,which is 3.6 times higher than that of soybean oil,and even higher than that of olive oil.展开更多
The effects of temperature and step-down relative humidity controlled hot-air drying(THC-HAD)on the drying kinetics,energy efficiency and quality,i.e.,rehydration ratio(RR),color parameters(L*,a*,b*),total color diffe...The effects of temperature and step-down relative humidity controlled hot-air drying(THC-HAD)on the drying kinetics,energy efficiency and quality,i.e.,rehydration ratio(RR),color parameters(L*,a*,b*),total color difference(ΔE*),Panax notoginseng saponins(PNS)content,and ginsenosides content(R1,Rg1,Re,Rd,Rb1)of Panax notoginseng roots were evaluated.The drying time was significantly affected by the drying temperature followed by the relative humidity(RH)of the drying air.Special combination of drying conditions,i.e.,drying temperature of 50°C,relative humidity of 40%for 3 h and then continuous dehumidification from 40%to 8%allowed to shorten the drying time by 25%compared to drying at the same temperature and continuous dehumidification.The longer was the drying time under constant high RH of drying air,the lower was the RR of dried samples.The step-down RH strategy contributed to the formation of a porous structure,enhancement of drying efficiency and quality improvement.Generally,the ginsenosides content increased with the increase in temperature,while no obvious trend was recorded for ginsenoside R1.The contents of the ginsenoside R1,Rg1,Rb1 and PNS decreased with the increase in the drying time under constant high RH.Taking into account the drying time,energy consumption and quality attributes,drying at the temperature of 50°C,constant RH of 40%for 3 h and then step-down RH from 40%to 8%was proposed as the most favorable combination of drying conditions for dehydration of whole Panax notoginseng roots.展开更多
Yellow maize as raw materials,hot air drying was used to reduce moisture content,and the tempering was implemented after drying.This study aimed to investigate the effects of hot air drying temperature and tempering t...Yellow maize as raw materials,hot air drying was used to reduce moisture content,and the tempering was implemented after drying.This study aimed to investigate the effects of hot air drying temperature and tempering time on the properties of maize starch.The wet milling was used to extract maize starch.Starch yield,protein content,amylose and amylopectin content,transparency and coagulation,solubility index and swelling power,color,pasting properties,and gelatinization properties were researched.The results showed that when the hot air temperature increased,the properties such as starch yield,amylopectin content,transparency,solubility,swelling power,whiteness decreased,and properties such as protein content and amylose content,coagulation,gelatinization temperature increased.Compared to drying temperature,tempering time has a less remarkable effect on the maize starch properties.The maize starch with better whiteness,solubility,swelling power could be obtained by adjusting tempering time.展开更多
Pufferfish is prone to deterioration due to abundant nutrients and high moisture content.Drying technology can extend the shelf life and enhance the flavor quality of aquatic products.The study investigated the effect...Pufferfish is prone to deterioration due to abundant nutrients and high moisture content.Drying technology can extend the shelf life and enhance the flavor quality of aquatic products.The study investigated the effect of hot air drying(HAD),microwave vacuum drying(MVD)and hot air assisted radio frequency drying(HARFD)on the taste and volatile profiles of Takifugu obscurus.Different drying methods had significant influence on the color,rehydration,5’-nucleotides,free amino acids and volatile components(P<0.05).The results showed that HAD and HARFD could promote the flavor of T.obscurus by producing higher equivalent umami concentration(EUC)values,which were about two times of MVD group,and more pronounced pleasant odor according to sensory analysis.HAD is more appropriate for industrial application than HARFD and MVD considering the economic benefits.This study could provide a reference for the industrial application of drying T.obscurus.展开更多
The main purpose of this study was to develop and apply an adaptive neuro-fuzzy inference system(ANFIS)and Artificial Neural Networks(ANNs)model for predicting the drying characteristics of potato,garlic and cantaloup...The main purpose of this study was to develop and apply an adaptive neuro-fuzzy inference system(ANFIS)and Artificial Neural Networks(ANNs)model for predicting the drying characteristics of potato,garlic and cantaloupe at convective hot air dryer.Drying experiments were conducted at the air temperatures of 40,50,60 and 70C and the air speeds of 0.5,1 and l.5 m/s.Drying properties were including kinetic drying,effective moisture diffusivity(Deff)and specific energy consumption(SEC).The highest value of Deff obtained 9.76×10^-9,0.13×10^-9 and 9.97×10^-10 m^2/s for potato,garlic,and cantaloupe,respectively.The lowest value of SEC for potato,garlic,and cantaloupe were calculated 1.94105,4.52105 and 2.12105 kJ/kg,respectively.Results revealed that the ANFIS model had the high ability to predict the Deff(R^2=0.9900),SEC(R^2=0.9917),moisture ratio(R^2=0.9974)and drying rate(R^2=0.9901)during drying.So ANFIS method had the high ability to evaluate all output as compared to ANNs method.展开更多
The flow fields of hot air in the dryer for drying colored potatoes of which characteristics are highly sensitive to the temperature were simulated using computational fluid dynamics(CFD)simulation.The local air veloc...The flow fields of hot air in the dryer for drying colored potatoes of which characteristics are highly sensitive to the temperature were simulated using computational fluid dynamics(CFD)simulation.The local air velocity decreased as the distance from the flow inlet increased.The mass and heat transfer coefficients increased from 0.666×10^(-2) m/s to 1.711×10^(-2) m/s,and 6.555 W/(m^(2)·K)to 16.834 W/(m^(2)·K),respectively,as the air velocity increased from 0.207 m/s to 1.567 m/s at 60°C.The drying simulation model using the heat and mass transfer model made accurate predictions.The thermal properties of colored potato,such as the thermal conductivity and specific heat,decreased significantly from 0.440 W/(m·K)to 0.034 W/(m·K)and 3906.45 J/(kg·K)to 2198.52 J/(kg·K),respectively,as the moisture content decreased from 78% to 5%.With the variable thermal and physical properties,the heat transfer simulation model made accurate predictions of the hot-air drying characteristics for the colored potatoes,and the RMSE values for all cases were(1.85±0.27)℃.展开更多
Chuño production is a kind of ancient method of potato preservation that has been used to the present day.In this study,physicochemical property and nutrition quality of white chuño(WC),black chuño,and ...Chuño production is a kind of ancient method of potato preservation that has been used to the present day.In this study,physicochemical property and nutrition quality of white chuño(WC),black chuño,and dehydrated potato flour prepared by hot air drying(AD)and freezing drying were analyzed and compared.The results revealed that the average particle size of the starch in WC is almost 10 times of the dehydrated potato flour by AD treatment according to the laser particle size meter.During the dehydration of WC,water-soluble minerals(K+,Mg2+),proteins,ascorbic acid,etc.were partly lost while Ca2+content increased dramatically.In addition,WC showed the lowest antioxidant capacity among the four different kinds of dehydrated potato products.The polyphenol oxidase activity of WC,black chuño and AD were between 0.62–12.2 U/g fresh weight,which indicated that the color will be stable when chuño was used as staple food ingredient in the subsequent process.Therefore,as a potato processed food,chuño displayed great potential for promotion in the cold and poor rural areas of the northern China.展开更多
Exploring new drying technology can help to deal with the challenge of better preservation of rhizome medicinal materials in the traditional Chinese medicine industry.In current work,combined infrared and hot-air dryi...Exploring new drying technology can help to deal with the challenge of better preservation of rhizome medicinal materials in the traditional Chinese medicine industry.In current work,combined infrared and hot-air drying(IR-HAD)was employed to Panax notoginseng roots and its effect on drying kinetics,energy efficiency and quality,i.e.,rehydration ratio(RR),color parameters(L^(*),a^(*),b^(*)),total color difference(ΔE),Panax notoginseng saponins(PNS)content,and ginsenosides content(R_(1),R^(g1),R_(e),R_(d),R_(b1))were evaluated.Hot air drying(HAD)was used as the control.Results showed that the increase in drying temperature significantly shortened drying time and reduced energy consumption.The shortest drying time of 43.0 h and lowest specific energy consumption of 15.9 kW·h/(kg-water)were obtained by IR-HAD at 55°C.The decrease of radiation distance and the increase of radiation power led to the shortening of drying time.However,high drying temperature resulted in largeΔE values,large collapse structure,and RR of samples.The drying time of Panax notoginseng roots dried by IR-HAD at a drying temperature of 50°C was shorter(15.5%)than HAD dried at the same drying temperature.The contents of R_(1),R_(g1),R_(e),R_(b1),and PNS were higher when the samples were dried by IR-HAD than those dried by HAD at the same temperature of 50°C.Moreover,the IR-HAD dried samples shortened 15.5%drying time and saved 22.1%energy consumption compared with HAD.Therefore,the optimal process condition was Panax notoginseng roots under IR-HAD at drying temperature of 50°C,radiation distance of 12 cm and radiation power of 1350 W,which can shorten drying time,maintain high ginsenosides contents and satisfactory apparent qualities.展开更多
Hot air(HA)drying of banana has low drying efficiency and results in undesirable product quality.The objectives of this research were to investigate the feasibility of infrared(IR)heating to improve banana drying rate...Hot air(HA)drying of banana has low drying efficiency and results in undesirable product quality.The objectives of this research were to investigate the feasibility of infrared(IR)heating to improve banana drying rate,evaluate quality of the dried product,and establish models for predicting drying characteristics.Banana slices of 5 mm and 8 mm thickness were dried with IR and HA at product temperatures of 60℃,70℃ and 80℃.Banana drying characteristics and changes in residual polyphenol oxidase(PPO),Hydroxymethylfurfural(HMF),color,moisture content(MC)and water activity during the treatments were investigated.Results showed that significant moisture reduction and higher drying rates were achieved with IR drying compared to HA drying in the early stage.The drying data could be fitted to the Page model for accurate prediction of MC change for IR and HA drying with mean R2 of 0.983.It was noted that enzyme inactivation occurred more quickly with IR than with HA drying.A unique response of PPO under IR and HA drying was revealed.IR heating of banana inactivated PPO within the first 20 min of drying at 60℃,70℃ and 80℃,while PPO was first activated before inactivation at 60℃ and 70℃ drying with HA.The highest HMF content occurred in banana slices with 5 mm thickness dried with IR at a product temperature of 80℃.It is therefore recommendable to dry banana with IR at product temperature of 70℃ or below to preserve the product quality.These findings are new and provide more insight in the application of IR heating for drying banana for improved drying rate and product quality.展开更多
Drying of a coated paper is modeled and simulated.The paper sheet is assumed to form three zones,and each zone has its own drying mechanism.Coupling of energy and mass balances must be used in order to solve different...Drying of a coated paper is modeled and simulated.The paper sheet is assumed to form three zones,and each zone has its own drying mechanism.Coupling of energy and mass balances must be used in order to solve differential equations.The simulations are carried out in various drying conditions i.e.,only hot air drying,only radiant drying,and mixed hot air-radiant drying.Also the effect of one side and two side assumption on evaporation is studied.Effect of venting air speed and radiant heat source presence and its distance from the drying surface on the drying of a coated paper has been studied.It is found that both distance and venting air speed are inversely related to drying in mixed hot air-radiant drying.Both surfaces participate in evaporation however,during the last time of drying,no difference between the upper and the bottom surfaces exist.展开更多
This paper attempts to analyze the kinetics involved in the drying of green peas in‘with blanching’and‘without blanching’techniques.Blanching by hot water mixed with a solution of citric acid(0.1–0.2 mg/ml)at 70...This paper attempts to analyze the kinetics involved in the drying of green peas in‘with blanching’and‘without blanching’techniques.Blanching by hot water mixed with a solution of citric acid(0.1–0.2 mg/ml)at 70C–100C is the treatment provided to the samples of green peas.Experimental analysis shows that the moisture content in green peas of three different sizes is reduced at different temperatures and demonstrates the effect of the rate of drying of the moisture content.Under different diameters and temperatures,the parameters are analyzed using‘with blanching’and‘without blanching’techniques.It is observed that‘with blanching’process plays a significant role in the reduction of moisture content under different temperatures and diameters in a lesser time as compared to‘without blanching’.The operative activation energy and moisture diffusivity are described by using Fick’s law of diffusion.The calculation of effective moisture diffusivity can be done via the utilization of slope.The drying data is subjected to two models of mathematical nature:Simple Exponential model,and Page model.The performance of these models is examined by means of comparing the coefficient of determination(R2),chi-square(v2)and root mean square error(RMSE)between the experimental and forecasted value of moisture ratio obtained‘with blanching’and‘without blanching’.The experimental data was seen to be in accordance with the Page model.The comparisons of energy consumption,energy efficiency and also the cost of the drying processes for‘with blanching’and‘without blanching’have been accomplished to optimize and reduce process condition and the cost of the process,respectively.展开更多
基金found by Guizhou Province Science and Technology Plan Project(No.Qiankeheji-ZK(2021)General 533)Domestic First-Class Discipline Construction Project in Guizhou Province(No.GNYL(2017)008)Guizhou Province Drug New Formulation New Process Technology Innovation Talent Team Project(No.Qiankehe Platform Talents(2017)5655).
文摘Background:To predict the moisture ratio of Radix isatidis extract during drying.Methods:Artificial neural networks were designed using the MATLAB neural network toolbox to produce a moisture ratio prediction model of Radix isatidis extract during hot air drying and vacuum drying,where regression values and mean squared error were used as evaluation indexes to optimize the number of hidden layer nodes and determine the topological structure of artificial neural networks model.In addition,the drying curves for the different drying parameters were analyzed.Results:The optimal topological structure of the moisture ratio prediction model for hot air drying and vacuum drying of Radix isatidis extract were“4-9-1”and“5-9-1”respectively,and the regression values between the predicted value and the experimental value is close to 1.This indicates that it has a high prediction accuracy.The moisture ratio gradually decreases with an increase in the drying time,reducing the loading,initial moisture content,increasing the temperature,and pressure can shorten the drying time and improve the drying efficiency.Conclusion:Artificial neural networks technology has the advantages of rapid and accurate prediction,and can provide a theoretical basis and technical support for online prediction during the drying process of the extract.
文摘The microwave coupled with hot air(MCHA)drying method was used in this test to dry hawthorn slices The effect of initial microwave power density level(6 W/g to 12 W/g),hot air temperature(55℃ to 70℃),and hot air velocity(1 m/s to 3 m/s)on the quality attributes of rehydration ratio(Rf),organic acid(OA)and ascorbic acid(AA)of the dehydrated hawthorn slices was analyzed using a response surface methodology.An orthogonal rotatable central composite with three factors and at five levels was used to develop predictive regression models for the responses.The prediction mathematical model of Rf,OA and AA of the hawthorn slice was determined by analysis of variance.Factor and response variables as well as the prediction mathematical model,the optimal drying process of Rf,OA and AA of the hawthorn slice were determined by using the Design-Expert software.The comprehensive optimal conditions were as follows:initial microwave power density 12 W/g,hot air temperature 55℃ and hot air velocity 1.56 m/s.
基金supported by the model and demonstration of comprehensive utilization of agricultural facilities based on the increasing income of tobacco farmers in Henan tobacco-growing area(Grant No.2018410000270095)the Special Project for scientists in the 13th Five-Year Plan of China's Agricultural Research System(CARS-04-PS25).
文摘Hot air temperature,hot air humidity,and hot wind speed were selected as independent variables of quadratic orthogonal rotation combination test design through single factor test.Drying time,energy consumption,chromatism value,luminosity value,hardness,rehydration ratio,and other indexes of the product were used as the response value of the test.Response surface methodology(RSM)was used to analyze the effects of independent variables on the quality of tiger nut(Cyperus esculentus L.),and the process parameters were combined and optimized.The results show that the suitable technological conditions for hot air drying of tiger nut are as follows:hot air temperature of 63.15°C,hot air humidity of 44.92%,hot air wind speed of 2.48 m/s.Under these conditions,the product has the advantages of the short drying cycle,low energy consumption,good color and luster,low hardness and good rehydration performance.The fatty acid composition and content of tiger nut oil were determined by gas chromatography.The fatty acid composition and content of tiger nut oil were compared with those of soybean oil,olive oil,rapeseed oil and sesame oil,the results show that among the saturated fatty acids in tiger nut oil,palm oil had the highest content of 11.172%,which was between soybean oil and olive oil.The main composition of unsaturated fatty acids in tiger nut oil is oleic acid,with a content of 77.605%,which is 3.6 times higher than that of soybean oil,and even higher than that of olive oil.
基金supported in part by the Hebei Province Key Research and Development Project(Grant No.203777119D,19227210D)in part by the Scientific Research Projects of Universities in Hebei Province(Grant No.ZD2021056)in part by the Hebei Province College and Middle School Students Science and Technology Innovation Ability Cultivation Project(Grant No.2021H060505)and part by China Agriculture Research System of MOF and MARA(CARS-21).
文摘The effects of temperature and step-down relative humidity controlled hot-air drying(THC-HAD)on the drying kinetics,energy efficiency and quality,i.e.,rehydration ratio(RR),color parameters(L*,a*,b*),total color difference(ΔE*),Panax notoginseng saponins(PNS)content,and ginsenosides content(R1,Rg1,Re,Rd,Rb1)of Panax notoginseng roots were evaluated.The drying time was significantly affected by the drying temperature followed by the relative humidity(RH)of the drying air.Special combination of drying conditions,i.e.,drying temperature of 50°C,relative humidity of 40%for 3 h and then continuous dehumidification from 40%to 8%allowed to shorten the drying time by 25%compared to drying at the same temperature and continuous dehumidification.The longer was the drying time under constant high RH of drying air,the lower was the RR of dried samples.The step-down RH strategy contributed to the formation of a porous structure,enhancement of drying efficiency and quality improvement.Generally,the ginsenosides content increased with the increase in temperature,while no obvious trend was recorded for ginsenoside R1.The contents of the ginsenoside R1,Rg1,Rb1 and PNS decreased with the increase in the drying time under constant high RH.Taking into account the drying time,energy consumption and quality attributes,drying at the temperature of 50°C,constant RH of 40%for 3 h and then step-down RH from 40%to 8%was proposed as the most favorable combination of drying conditions for dehydration of whole Panax notoginseng roots.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.31271972,No.31671907,No.52006109)and the University Science and Technology Innovation Team Support Plan of Henan Province of China in 2016(16IRTSTHN009).
文摘Yellow maize as raw materials,hot air drying was used to reduce moisture content,and the tempering was implemented after drying.This study aimed to investigate the effects of hot air drying temperature and tempering time on the properties of maize starch.The wet milling was used to extract maize starch.Starch yield,protein content,amylose and amylopectin content,transparency and coagulation,solubility index and swelling power,color,pasting properties,and gelatinization properties were researched.The results showed that when the hot air temperature increased,the properties such as starch yield,amylopectin content,transparency,solubility,swelling power,whiteness decreased,and properties such as protein content and amylose content,coagulation,gelatinization temperature increased.Compared to drying temperature,tempering time has a less remarkable effect on the maize starch properties.The maize starch with better whiteness,solubility,swelling power could be obtained by adjusting tempering time.
基金supported by The National Natural Science Foundation of China (32001824, 31972198, 31901813, 31901816, 32001827)Startup Fund for Youngman Research at SJTU (SFYR at SJTU)
文摘Pufferfish is prone to deterioration due to abundant nutrients and high moisture content.Drying technology can extend the shelf life and enhance the flavor quality of aquatic products.The study investigated the effect of hot air drying(HAD),microwave vacuum drying(MVD)and hot air assisted radio frequency drying(HARFD)on the taste and volatile profiles of Takifugu obscurus.Different drying methods had significant influence on the color,rehydration,5’-nucleotides,free amino acids and volatile components(P<0.05).The results showed that HAD and HARFD could promote the flavor of T.obscurus by producing higher equivalent umami concentration(EUC)values,which were about two times of MVD group,and more pronounced pleasant odor according to sensory analysis.HAD is more appropriate for industrial application than HARFD and MVD considering the economic benefits.This study could provide a reference for the industrial application of drying T.obscurus.
文摘The main purpose of this study was to develop and apply an adaptive neuro-fuzzy inference system(ANFIS)and Artificial Neural Networks(ANNs)model for predicting the drying characteristics of potato,garlic and cantaloupe at convective hot air dryer.Drying experiments were conducted at the air temperatures of 40,50,60 and 70C and the air speeds of 0.5,1 and l.5 m/s.Drying properties were including kinetic drying,effective moisture diffusivity(Deff)and specific energy consumption(SEC).The highest value of Deff obtained 9.76×10^-9,0.13×10^-9 and 9.97×10^-10 m^2/s for potato,garlic,and cantaloupe,respectively.The lowest value of SEC for potato,garlic,and cantaloupe were calculated 1.94105,4.52105 and 2.12105 kJ/kg,respectively.Results revealed that the ANFIS model had the high ability to predict the Deff(R^2=0.9900),SEC(R^2=0.9917),moisture ratio(R^2=0.9974)and drying rate(R^2=0.9901)during drying.So ANFIS method had the high ability to evaluate all output as compared to ANNs method.
基金This work was supported by Korea Institute of Planning and Evaluation for Technology in Food,Agriculture,Forestry and Fisheries(IPET)thorugh High Value-added Food Technology Development Program,funded by Minstry of Agriculture,Food and Rural Affairs(Grant No.314047-2)This study has been worked with the support of a research grant of Kangwon National University in 2016.
文摘The flow fields of hot air in the dryer for drying colored potatoes of which characteristics are highly sensitive to the temperature were simulated using computational fluid dynamics(CFD)simulation.The local air velocity decreased as the distance from the flow inlet increased.The mass and heat transfer coefficients increased from 0.666×10^(-2) m/s to 1.711×10^(-2) m/s,and 6.555 W/(m^(2)·K)to 16.834 W/(m^(2)·K),respectively,as the air velocity increased from 0.207 m/s to 1.567 m/s at 60°C.The drying simulation model using the heat and mass transfer model made accurate predictions.The thermal properties of colored potato,such as the thermal conductivity and specific heat,decreased significantly from 0.440 W/(m·K)to 0.034 W/(m·K)and 3906.45 J/(kg·K)to 2198.52 J/(kg·K),respectively,as the moisture content decreased from 78% to 5%.With the variable thermal and physical properties,the heat transfer simulation model made accurate predictions of the hot-air drying characteristics for the colored potatoes,and the RMSE values for all cases were(1.85±0.27)℃.
基金supported by the earmarked fund for CARS(Grant No.CARS-09)High Technology Industrialization of Sccience and Technology Cooperation Between Jilin Province and Chinese Academy of Sciences(Grant No.2021SYHZ0005)Key Research and Development Plan of Ningxia Hui Autonomous Region(Grant No.2020BBF03018).
文摘Chuño production is a kind of ancient method of potato preservation that has been used to the present day.In this study,physicochemical property and nutrition quality of white chuño(WC),black chuño,and dehydrated potato flour prepared by hot air drying(AD)and freezing drying were analyzed and compared.The results revealed that the average particle size of the starch in WC is almost 10 times of the dehydrated potato flour by AD treatment according to the laser particle size meter.During the dehydration of WC,water-soluble minerals(K+,Mg2+),proteins,ascorbic acid,etc.were partly lost while Ca2+content increased dramatically.In addition,WC showed the lowest antioxidant capacity among the four different kinds of dehydrated potato products.The polyphenol oxidase activity of WC,black chuño and AD were between 0.62–12.2 U/g fresh weight,which indicated that the color will be stable when chuño was used as staple food ingredient in the subsequent process.Therefore,as a potato processed food,chuño displayed great potential for promotion in the cold and poor rural areas of the northern China.
文摘Exploring new drying technology can help to deal with the challenge of better preservation of rhizome medicinal materials in the traditional Chinese medicine industry.In current work,combined infrared and hot-air drying(IR-HAD)was employed to Panax notoginseng roots and its effect on drying kinetics,energy efficiency and quality,i.e.,rehydration ratio(RR),color parameters(L^(*),a^(*),b^(*)),total color difference(ΔE),Panax notoginseng saponins(PNS)content,and ginsenosides content(R_(1),R^(g1),R_(e),R_(d),R_(b1))were evaluated.Hot air drying(HAD)was used as the control.Results showed that the increase in drying temperature significantly shortened drying time and reduced energy consumption.The shortest drying time of 43.0 h and lowest specific energy consumption of 15.9 kW·h/(kg-water)were obtained by IR-HAD at 55°C.The decrease of radiation distance and the increase of radiation power led to the shortening of drying time.However,high drying temperature resulted in largeΔE values,large collapse structure,and RR of samples.The drying time of Panax notoginseng roots dried by IR-HAD at a drying temperature of 50°C was shorter(15.5%)than HAD dried at the same drying temperature.The contents of R_(1),R_(g1),R_(e),R_(b1),and PNS were higher when the samples were dried by IR-HAD than those dried by HAD at the same temperature of 50°C.Moreover,the IR-HAD dried samples shortened 15.5%drying time and saved 22.1%energy consumption compared with HAD.Therefore,the optimal process condition was Panax notoginseng roots under IR-HAD at drying temperature of 50°C,radiation distance of 12 cm and radiation power of 1350 W,which can shorten drying time,maintain high ginsenosides contents and satisfactory apparent qualities.
文摘Hot air(HA)drying of banana has low drying efficiency and results in undesirable product quality.The objectives of this research were to investigate the feasibility of infrared(IR)heating to improve banana drying rate,evaluate quality of the dried product,and establish models for predicting drying characteristics.Banana slices of 5 mm and 8 mm thickness were dried with IR and HA at product temperatures of 60℃,70℃ and 80℃.Banana drying characteristics and changes in residual polyphenol oxidase(PPO),Hydroxymethylfurfural(HMF),color,moisture content(MC)and water activity during the treatments were investigated.Results showed that significant moisture reduction and higher drying rates were achieved with IR drying compared to HA drying in the early stage.The drying data could be fitted to the Page model for accurate prediction of MC change for IR and HA drying with mean R2 of 0.983.It was noted that enzyme inactivation occurred more quickly with IR than with HA drying.A unique response of PPO under IR and HA drying was revealed.IR heating of banana inactivated PPO within the first 20 min of drying at 60℃,70℃ and 80℃,while PPO was first activated before inactivation at 60℃ and 70℃ drying with HA.The highest HMF content occurred in banana slices with 5 mm thickness dried with IR at a product temperature of 80℃.It is therefore recommendable to dry banana with IR at product temperature of 70℃ or below to preserve the product quality.These findings are new and provide more insight in the application of IR heating for drying banana for improved drying rate and product quality.
文摘Drying of a coated paper is modeled and simulated.The paper sheet is assumed to form three zones,and each zone has its own drying mechanism.Coupling of energy and mass balances must be used in order to solve differential equations.The simulations are carried out in various drying conditions i.e.,only hot air drying,only radiant drying,and mixed hot air-radiant drying.Also the effect of one side and two side assumption on evaporation is studied.Effect of venting air speed and radiant heat source presence and its distance from the drying surface on the drying of a coated paper has been studied.It is found that both distance and venting air speed are inversely related to drying in mixed hot air-radiant drying.Both surfaces participate in evaporation however,during the last time of drying,no difference between the upper and the bottom surfaces exist.
文摘This paper attempts to analyze the kinetics involved in the drying of green peas in‘with blanching’and‘without blanching’techniques.Blanching by hot water mixed with a solution of citric acid(0.1–0.2 mg/ml)at 70C–100C is the treatment provided to the samples of green peas.Experimental analysis shows that the moisture content in green peas of three different sizes is reduced at different temperatures and demonstrates the effect of the rate of drying of the moisture content.Under different diameters and temperatures,the parameters are analyzed using‘with blanching’and‘without blanching’techniques.It is observed that‘with blanching’process plays a significant role in the reduction of moisture content under different temperatures and diameters in a lesser time as compared to‘without blanching’.The operative activation energy and moisture diffusivity are described by using Fick’s law of diffusion.The calculation of effective moisture diffusivity can be done via the utilization of slope.The drying data is subjected to two models of mathematical nature:Simple Exponential model,and Page model.The performance of these models is examined by means of comparing the coefficient of determination(R2),chi-square(v2)and root mean square error(RMSE)between the experimental and forecasted value of moisture ratio obtained‘with blanching’and‘without blanching’.The experimental data was seen to be in accordance with the Page model.The comparisons of energy consumption,energy efficiency and also the cost of the drying processes for‘with blanching’and‘without blanching’have been accomplished to optimize and reduce process condition and the cost of the process,respectively.
