农业工程学报
農業工程學報
농업공정학보
2014年
17期
321-327
,共7页
金亚美%杨哪%焦爱权%吴凤凤%金征宇%徐学明
金亞美%楊哪%焦愛權%吳鳳鳳%金徵宇%徐學明
금아미%양나%초애권%오봉봉%금정우%서학명
磁场%腌渍%传质%芥菜%流体电解质%扩散系数
磁場%醃漬%傳質%芥菜%流體電解質%擴散繫數
자장%업지%전질%개채%류체전해질%확산계수
magnetic fields%pickling%mass transfer%tuber mustard%flowing electrolyte%diffusion coefficient
为了实现对芥菜的快速腌渍,采用磁场和流动盐液相结合的方式对样品进行处理,并与静置条件下的腌渍进行了对比。利用不同磁感应强度的磁场(200、1000、2000 Gs)和流速场(0.03、0.06、0.22 m/s)完成对芥菜的腌渍处理,同时考察了传质动力学方程。结果表明:当腌渍条件于磁感应强度2000 Gs和流速0.06 m/s时,可在180 min时间内使样品表层盐分达到饱和,盐分扩散系数为k=2.35×10-2 min-1,而当腌渍液处于湍流(0.22 m/s,雷诺数Re=4132)的情况下则不利于盐分扩散,只施加磁场的静置腌渍对传质无显著提高(P>0.05),而当腌渍液在层流状态下(雷诺数 Re=563和1127)则有利于盐分向多孔状原料的渗透,最佳工艺参数为磁感应强度 B=2000 Gs 和流速 v=0.06 m/s 且该条件下的传质动力学模型可采用 Logistic 方程进行描述,预测方程决定系数为R2=0.976,该研究为农产品快速浸渍加工提供了参考。
為瞭實現對芥菜的快速醃漬,採用磁場和流動鹽液相結閤的方式對樣品進行處理,併與靜置條件下的醃漬進行瞭對比。利用不同磁感應彊度的磁場(200、1000、2000 Gs)和流速場(0.03、0.06、0.22 m/s)完成對芥菜的醃漬處理,同時攷察瞭傳質動力學方程。結果錶明:噹醃漬條件于磁感應彊度2000 Gs和流速0.06 m/s時,可在180 min時間內使樣品錶層鹽分達到飽和,鹽分擴散繫數為k=2.35×10-2 min-1,而噹醃漬液處于湍流(0.22 m/s,雷諾數Re=4132)的情況下則不利于鹽分擴散,隻施加磁場的靜置醃漬對傳質無顯著提高(P>0.05),而噹醃漬液在層流狀態下(雷諾數 Re=563和1127)則有利于鹽分嚮多孔狀原料的滲透,最佳工藝參數為磁感應彊度 B=2000 Gs 和流速 v=0.06 m/s 且該條件下的傳質動力學模型可採用 Logistic 方程進行描述,預測方程決定繫數為R2=0.976,該研究為農產品快速浸漬加工提供瞭參攷。
위료실현대개채적쾌속업지,채용자장화류동염액상결합적방식대양품진행처리,병여정치조건하적업지진행료대비。이용불동자감응강도적자장(200、1000、2000 Gs)화류속장(0.03、0.06、0.22 m/s)완성대개채적업지처리,동시고찰료전질동역학방정。결과표명:당업지조건우자감응강도2000 Gs화류속0.06 m/s시,가재180 min시간내사양품표층염분체도포화,염분확산계수위k=2.35×10-2 min-1,이당업지액처우단류(0.22 m/s,뢰낙수Re=4132)적정황하칙불리우염분확산,지시가자장적정치업지대전질무현저제고(P>0.05),이당업지액재층류상태하(뢰낙수 Re=563화1127)칙유리우염분향다공상원료적삼투,최가공예삼수위자감응강도 B=2000 Gs 화류속 v=0.06 m/s 차해조건하적전질동역학모형가채용 Logistic 방정진행묘술,예측방정결정계수위R2=0.976,해연구위농산품쾌속침지가공제공료삼고。
Pickling is considered to be the most effective method of preserving food materials and of preventing spoilage. Commercial pickled tuber mustard with special favor is very popular in China. Most agricultural raw materials and food itself is porous to a certain extent, favoring ion diffusion. Salting is time-consuming process;therefore, some techniques in salting process has been applied to reduce salting time, such as vacuum impregnation, ultrasound technique and pulsed pressure treatment. Electrolyte solution contains a large number of charged ions such as Na+, Cl-, H+, Ca2+, Mg2+ and OH-. The movement of charged ions can be affected by the Lorentz force in the perpendicular magnetic field which induces large-scale mass transfer and migration in a fixed direction. In this study, the low-cost static magnetic field system has been designed which utilized modern NdFeB permanent magnets as the source for the required magnetic flux. The two blocks of NdFeB magnets(100 mm× 100 mm×15 mm, Br=0.5 T) were arranged in parallel, and placed with iron yokes in a way that a magnetic flux density B was generated by adjusting its distance. The magnetic flux densities between the parallel magnets measured by Teslameter, were 200 Gs, 1000 Gs and 2000 Gs, respectively, which were known to be strong enough to have the magnetic effect on the movement of ions. Simultaneously, these magnet systems provided sufficient free space to place the samples. The sample was placed parallel to the direction of magnetic field lines. Then tuber mustard salting by flowing saline was conducted in magnetic field at different treatment conditions. The flow rates of saline solution were respectively 0.03 m/s (Re=563), 0.06 m/s (Re=1127) and 0.22 m/s (Re=4132) corresponding to laminar flow and turbulence. In the experiment, the sampling period was 10 minutes, and then mass fraction of NaCl in the sample was determined after a 3-hour brining period. The mass transfer kinetic model has been investigated for evaluation of salt content in the samples during pickling. All measurements were performed in the laboratory at average room temperature of 20 oC. Three replicates of each sample were used for statistical analysis. The results showed that mass fraction of NaCl in the sample reached maximum at the magnetic flux density of 2000 Gs and flowing velocity of 0.06 m/s within the salting period. At this point the salinity diffusion coefficient was highest (k=2.35·10-2 min-1). The turbulence in saline solution was not conducive to the diffusion of salt into the sample with the lowest diffusion coefficient (k=0.34·10-2 min-1 and 0.31·10-2 min-1) at 0.22 m/s. There was no significant increase in mass fraction of NaCl in tuber mustard immersed by the static saline solution under the perpendicular magnetic field. However, saline solution in laminar flow conditions was conducive to the diffusion of free ions into the porous plant materials with the action of the Lorentz force. Analysis of mass transfer in sample demonstrated that using the Logistic kinetics model, the highest correlation coefficient of the equations was 0.989. The technology achieves the rapid salting for agric-products.