Effects of Chemical Osmotic Pretreatment on Drying Characteristics and Quality of Blueberry under Hot Air Drying

In order to study the effects of chemical osmotic pretreatment on the characteristics and quality of blueberry under hot air drying,fresh blueberries were pretreated with 2.5 g/100 mL K2CO3+0.6 g/100 mL olive oil,and 5.0 g/100 mL K2CO3+0.6 g/100 mL olive oil at(45±0.5)℃,respectively.The changes of water content,rehydration,hardness,microstructure,color difference,active ingredient anthocyanin,total phenol and DPPH radical scavenging capacity of dried blueberries in different treatment groups under hot air drying were compared and analyzed.The results showed that the dehydration rates of blueberries vary greatly according to the type of pretreatments when the samples were dried to the same water content with hot air.Specifically,the dehydration rate of dried blueberries pretreated by 5.0%K2CO3 solution was the highest,followed by 2.5%K2CO3 osmotic pretreatment and lastly the control group;the corresponding dehydration time was 10,14 and 20h,respectively.The physical qualities of dried blueberries,involving the browning degree,color difference,rehydration and microstructure,were significantly different between the chemical osmotic pretreatment group and the control group(P<0.05).The chemical osmotic pretreatment of K2CO3 solution increased the dehydration rate of the samples,shortened the drying time and maintained the quality of blueberries dried with hot air.There was no significant difference between the physical quality of dried blueberries pretreated by 2.5%and 5.0%K2CO3 solution(P>0.05),whereas there was significant difference in drying time and nutrient quality which is characterized by total phenols,anthocyanins,DPPH radical scavenging rate,soluble total sugar(P<0.05).Conclusion:5.0%K2CO3 osmotic pretreatment combining with hot air drying can improve the dehydration rate,shorten the drying time and maintain the physical and nutritional quality.

Effect of different drying methods on the taste and volatile compounds,sensory characteristics of Takifugu obscurus

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.

Artificial neural network techniques to predict the moisture ratio content during hot air drying and vacuum drying of Radix isatidis extract

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.

Polyphenol Oxidase Activity and Colour Changes of ‘Starking’ Apple Cubes Coated with Alginate and Dehydrated with Air

The objective was to study the effect of alginate coating on polyphenol oxidase (PPO) activity and colour of ‘Starking’ apple cubes during dehydration with hot air. Apple cubes were dehydrated at 20oC, 35oC, or 40oC, with a parallel airflow. Analysis of PPO activity, colour (L*, a*, b*) and dry matter were performed along the dehydration process at each temperature. All samples presented a peak in relative PPO activity in the beginning of the drying. Exponential models fitted well the experimental data after the peak. Cubes without coating presented lower PPO activity, suggesting lower browning, than coated samples throughout the dehydration process, for all temperatures. Better results for coated samples were obtained with a perpendicular airflow drying at 40oC, after dipping the whole apple in water at 60oC for 10 min. In order to prevent coated samples from browning, drying by perpendicular airflow preceded by a thermal treatment of the whole apple is required.

切片厚度和护色处理对热风干燥雪花梨干品质的影响

采用热风干燥法制备雪花梨干。以色泽、硬度、弹性、咀嚼性、总酚、总黄酮、可溶性糖和感官评分为评价指标,考察切片厚度(3、4、5、6、7、8 mm)和护色处理(CaCl_(2)、NaCl、D-异抗坏血酸钠、柠檬酸溶液浸泡、热烫)对梨干品质的影响,并以Z-score(Z值)综合模型进行评价,优选出适宜的切片厚度和护色处理。结果表明:随着切片厚度的增加,梨干的颜色变深,硬度、弹性和咀嚼性增大,总酚和总黄酮含量降低,可溶性糖含量增加;Z-score综合模型评价结果显示,切片厚度为4 mm时,Z值总和最高。护色处理均能改善梨干色泽,提高总酚和总黄酮含量,但可溶性糖含量降低。D-异抗坏血酸钠处理组梨干的亮度值(L^(*))最高,红绿值(a^(*))和蓝黄值(b^(*))最低,色差值(ΔE)最小;CaCl_(2)处理提高了梨干的硬度;热烫处理降低了梨干的弹性和咀嚼性。Z-score综合模型评价结果显示,以0.8 g/100 mL D-异抗坏血酸钠溶液浸泡护色的Z值总和最高。综上,热风干燥制备雪花梨干的厚度和护色条件为:切片厚度4 mm、0.8 g/100 mL D-异抗坏血酸钠溶液浸泡10 min。

Influence of Different Drying Temperatures on Quality of Balsam Pear Slices

[Objective] The aim was to investigate the effects of different drying temperatures on the physiochemical properties and antioxidant activity of balsam pear slices. [Method] Balsam pear slices were dried at different hot air temperatures, 40, 50, 60, 70 and 80 ℃. [Result] The polyphenols content was highest （2.83 mg/g） in the balsam pear slices dried at 50 ℃, and the flavonoids content was highest （2.584 mg/g） in those dried at 60 ℃. Different drying temperatures had a great impact on the antioxidant capacity of polyphenols in balsam pear. The balsam pear slices dried at 50 ℃ showed the strongest capacity for scavenging DPPH free radicals with IC50 of 0.015 mg/ml, and those dried at 80 ℃ showed the strongest capacity for removing ABTS free radicals with IC50 of 0.0689 mg/ml. [Conclusion] The hot air temperature of 50 ℃ had the least impact on the quality of balsam pear slices.

HACCP体系在热风干制荔枝果肉加工中的应用

为了确保热风干制荔枝果肉的品质和安全,应用危害分析与关键控制点(HACCP)原理对荔枝果肉热风干制加工过程中各工序及其潜在危害进行分析,确定了原料、热烫、护色、热风干燥、检验、包装、运输销售7个工序为关键控制点,建立了相应工序的关键控制临界值,并制定了危害分析表和HACCP工作表。

5种干燥方式对木薯酸淀粉性能的影响

为探究不同干燥方法对木薯酸淀粉性能的影响,本研究以木薯淀粉为原料,经乳酸菌发酵后,采用热风干燥、热泵干燥、真空冷冻干燥、喷雾干燥和太阳光晒干5种干燥方法制备木薯酸淀粉,对其性能进行测定分析,并采用变异系数法对性能进行综合评分。结果表明,热风干燥的木薯酸淀粉粒径跨度最大,为2.36,透明度、碘蓝值和持油性最小,分别为21.57%、8.96和1.74 g/g;热泵干燥的木薯酸淀粉比表面积最小,为351.83 m2/kg,堆积密度、析水率和凝沉性最高,分别为0.87 g/mL、33.02%和74.89%;真空冷冻干燥的木薯酸淀粉堆积密度、休止角和析水率最低,分别为0.73 g/mL、37.49°和4.64%,透明度、碘蓝值和持水性最高,分别为27.03%、19.64和1.43 g/g,溶解性最高;喷雾干燥的木薯酸淀粉比表面积、休止角和持油性最高,分别为407.43 m2/kg、54.11°和2.33 g/g,凝沉性最低,为67.00%;晒干的木薯酸淀粉跨度和持水性最低,分别为1.73和1.08 g/g。综合评分结果显示,真空冷冻、喷雾、晒干、热风和热泵干燥的木薯酸淀粉性能综合评分分别为0.60、0.38、0.18、-0.50和-0.64。综合分析,真空冷冻干燥制备的木薯酸淀粉性能最好,其次为喷雾干燥,晒干次之,热风和热泵干燥的最差。

Parameter optimization for microwave coupled with hot air drying process of hawthorn slices using response-surface methodology

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.

Effects of air movement in a hot air dryer on the drying characteristics of colored potato (Solanum tuberosum L.) using computational fluid dynamics

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)℃.

Effects of combined infrared and hot-air drying on ginsenosides and drying characteristics of Panax notoginseng(Araliaceae)roots

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.

The Influence of Drying Temperature and Extraction Methods on a-Mangostin in Mangosteen Pericarp

The effects of drying temperature and extraction methods on α-mangostin content in mangosteen pericarp （Garcinia mangostana L.） powder were investigated. In the first part of experiment suitable drying temperature for retention α-mangostin content was determined. Three levels of drying temperatures （55, 65 and 75 ℃） were used in this study. The drying rates were increased with drying temperature. Room temperature extraction method was performed to investigate the effect of drying temperature on retention α-mangostin content in mangosteen pericarp. The α-mangostin content extracted at three different drying temperatures （55, 65 and 75 ℃） was 35.98 ± 0.49%, 40.32 ± 0.24%, and 37.79±0.34% w/w, respectively. The results showed that the suitable temperature for drying mangosteen pericarp was 65 ℃ that gave the highest of α-mangostin content. The second part of experiment was the comparison between extraction methods, such as shaking water bath extraction （SWE）, soxhlet extraction （SE） and microwave-assisted extraction （MAE）. The results show that MAE gave the highest extraction rate and α-mangostin content as compare to SWE and SE. The α-mangostin content extraction from SWE, SE and MAE are 45.83 ± 0.02, 34.82± 0.17 and 49.79 ± 0.15% w/w of crude extract, respectively.

Analysis of the Influence of Different Drying Methods on the Active Ingredients of Fresh Medicine

The heating area of the material is large and the thermal efficiency is high,but it is n ecessary to control the suitable drying temperature ofdiffere nt medici nal materials to preserve the effective in gredients.D iff ere nt kinds of Chinese medicine need different drying conditions to fulfill good drying requirements.Natural drying in the shade is one of the traditional drying methods,which takes a long time and is easily affected by the weather.The water volatilizes slowly.It is prone to mildew and discoloration during the drying process.However,it can better preserve the volatile oil components of Chinese medicine.The hot-air drying machine has lower requirements.The medicinal materials have a large heating area and high thermal efficiency,but it is necessary to control the appropriate drying temperature of different medicinal materials in order to preserve the active ingredients of the medicinal materials;it is not suitable for medicinal materials that stick and bind easily.The microwave drying method possesses superiority in drying some valuable medicinal materials such as Ren she n(Radix et Rhizoma Ginseng)and Lurong(Co「nu Cervi Pantotrichum),and the effective ingredients are preserved at a high degree;it can also achieve the purpose of killing enzymes and protecting glycosides and have a good bactericidal effect,but it is not suitable for Chinese medicines containing heat-sensitive ingredients,because it will destroy most of the proteins,amino acids,and peptides of Chinese medicine and result in the loss of efficacy.The far-infrared drying method is suitable for drying thin-layer medicinal materials and is friendly to the environment.Freeze-drying can preserve the active ingredients very well and greatly retain the efficacy,but it has obvious limitations in preserving some Chinese medicinal materials that need to kill enzymes and protect glycosides;besides,the cost is relatively high and the drying time is long.

添加赖氨酸的猪肉脯在不同干燥温度下的质构稳定性

为改善猪肉脯在不同热风干燥温度下的质构稳定性,研究在干燥温度55~75℃条件下添加0.25%~0.75%赖氨酸对猪肉脯质构稳定性的影响。结果表明:添加0.50%赖氨酸可显著降低高温(70~75℃)干燥下猪肉脯的硬度和内聚性(P<0.05),显著提高其弹性(P<0.05),减小猪肉脯硬度、弹性、内聚性和咀嚼性在干燥温度55~75℃条件下的极差值,并可在(60±5)℃和(65±5)℃变化范围内将猪肉脯咀嚼性的极差值控制在1.4%以内;赖氨酸可能通过提高并稳定猪肉脯体系pH值、改善微观结构、提高肉蛋白及其二级结构的热稳定性、增强内部氢键作用力和水分流动性、阻滞肌球蛋白热降解等作用,提升猪肉脯在不同干燥温度下的质构稳定性。

虾青素对热风干制凡纳滨对虾香气特性的影响

【目的】研究虾青素对热风干制凡纳滨对虾(Litopenaeus vannamei)香气特征的影响。【方法】采用电子鼻和感官评定表征虾青素与虾干制品的感官特性,运用GC-MS分析虾青素对虾干制品挥发性化合物的影响,以气味活性值(IOAV)为依据筛选香气活性化合物,采用偏最小二乘回归法(PLSR)分析香气活性化合物与感官属性之间的相关性。【结果】虾青素对虾干整体香气的形成有重要影响,可促进虾干肉香味、烤香味与焦糖味的形成,但对腥味形成具有抑制作用。虾青素可促进虾干挥发性化合物的形成,其中吡嗪类化合物增加最为显著。实验结果表明,添加虾青素标准品和添加虾青素提取物的虾干中吡嗪类化合物的I_(OAV)分别增加50.00%和40.09%,其中2,5-二甲基吡嗪的IOAV增长最快,分别增加42.44%和48.99%,但对三甲胺的产生有明显的抑制作用,三甲胺的IOAV分别减少43.21%和52.89%。PLSR结果表明,香气活性化合物与感官属性之间存在良好的相关性。【结论】虾青素能改进热风干制凡纳滨对虾的香气特性,研究结果可为解析虾青素在虾干制品中香气形成机制提供参考。

Optimization of hot air drying process for tiger nut and analysis of fatty acid composition of tiger nut oil

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.

ANFIS and ANNs model for prediction of moisture diffusivity and specific energy consumption potato,garlic and cantaloupe drying under convective hot air dryer

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 70
C 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 1.94
105,4.52
105 and 2.12
105 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.

Process performance and quality attributes of temperature and step-down relative humidity controlled hot air drying of Panax notoginseng roots

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.

Effects of hot air drying temperature and tempering time on the properties of maize starch

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.

Physico-chemical properties and nutrition quality of potato flour: chuño vs modern processing technology

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.