电磁场对细胞冻结特性的影响
发布时间：2018-09-04 06:46
【摘要】：近几十年来,无线电技术的飞速发展使其渗透到人类生产生活的各个方面,随之而来的电磁场对生物体的影响作用逐渐为人们所关注,有关电磁生物效应的研究指出电磁场对生物的多项生理活动中具有影响作用。而在食品低温保存领域,传统的低温冻结保存方式对食品品质会造成损害,玻璃化冻结方式比起传统相变冻结过程虽然具有种种优势,但实现难度过大、实际操作性不强。鉴于食品材料大多属于生物材料,因此我们提出将电磁生物效应和食品冷冻冷藏相结合,探讨电磁场对食品材料冻结过程中相变阶段的作用。本文利用自主设计的亥姆霍兹线圈磁场作用于洋葱等果蔬细胞组织的冻结过程,并在此过程中利用带摄像功能的Olympus BX51低温显微镜对冻结过程进行全程显微拍摄,旨在探究不同形式和场强的电磁场对于果蔬细胞相变过程中冰晶形状和大小的作用以及磁场冻结方式对细胞形态和大小的影响。实验采用Linkam BCS196低温台以液氮供冷的方式对果蔬细胞组织进行冻结,其降温过程温度精度可达0.01℃;实验所采用的磁场形式有:直流磁场和交流磁场两种,磁场强度分别有:4.6Gs、9Gs、18Gs、36Gs、72Gs五组;鉴于水及水溶液在细胞冻结相变过程中的重要作用,本文还对水及0.9%浓度KMn O4溶液在上述条件下进行了实验研究。通过以上实验我们获取了大量的图片数据。研究发现:一.磁场对水及水溶液冻结过程的影响1.冻结过程中磁场的介入在一定程度上可以降低水及水溶液的过冷度。4.6Gs、9Gs、18Gs、36Gs、72Gs五组磁场作用下相比对照组使得过冷度分别降低了1.62℃、1.68℃、1.65℃、2.23℃、2.55℃;2.从统计规律来看,相变过程中冰晶大小相比对照组要细小,其中水和KMn O4溶液在磁场作用下冻结过程冰晶平均大小分别约为对照组的67%和76%。二.磁场对洋葱、胡萝卜、黄瓜、西葫芦等果蔬冻结过程的影响1.磁场辅助冻结过程中细胞组织在相变过程中生成的冰晶趋向于雾化、沙粒化,而对照组冰晶形状则多趋向于偏大的刀片状和块状;2.磁场辅助的果蔬细胞冻结过程过冷度相比对照组要低,相变过程被推迟。其中5种场强作用下4种果蔬冻结过程过冷度相对于对照组均有所降低;总体来看,随着场强增大过冷度降低的幅度减小;3.磁场作用下相变过程时间缩短,其中5种场强作用下4种果蔬的相变过程时间相对于对照组均有所缩短,且缩短的程度随场强增大而增大;4.作者在对果蔬细胞冻结效果评价方面提出“细胞二维保持率ζ”这一指标,并可利用Auto CAD软件对显微图像进行数据计算得出ζ值,其中4种果蔬在5种场强作用下冻结过程的“细胞二维保持率ζ”均比对照组高,但四种果蔬的ζ值随场强变化规律并不一致。综上可知,通过对水及水溶液、果蔬细胞在磁场作用下冻结的研究可以得出磁场有推迟相变过程、抑制冰晶形成以及更好地保护细胞结构的作用,其机理可能是磁场作用下水分子及其团簇的抗磁性所产生的附加磁矩扰乱了它本身的无规则热运动从而造成了相变过程成核势垒增大、流动性降低最终导致过冷度降低、冰晶尺寸减小等作用。以上作用使得磁场辅助冻结过程相比传统的冷冻冷藏方式具有减小冻结过程冰晶对果蔬细胞破坏程度、尽可能保持果蔬品质和风味的作用,在未来应该会有可观的研究价值和利用价值。
[Abstract]:In recent decades, the rapid development of radio technology has made it penetrate into all aspects of human production and life, and the consequent effect of electromagnetic fields on organisms has gradually attracted people's attention. Although vitrification freezing method has many advantages over traditional phase change freezing method, it is difficult to realize and is not practical. Since most food materials belong to biological materials, we propose to combine electromagnetic biological effects with food freezing and refrigeration. In this paper, the freezing process of onion and other fruit and vegetable cell tissues was studied by using the self-designed Helmholtz coil magnetic field, and the whole freezing process was photographed by Olympus BX51 cryogenic microscope with camera function. The effect of electromagnetic field of the same form and intensity on the shape and size of ice crystal and the effect of magnetic field freezing on cell morphology and size in the process of fruit and vegetable cell transformation were studied. There are two types of magnetic field: direct current magnetic field and alternating current magnetic field, and the magnetic field intensity is 4.6Gs, 9Gs, 18Gs, 36Gs, 72Gs, respectively. In view of the important role of water and aqueous solution in the process of cell freezing and phase transformation, water and 0.9% concentration of KMn O4 solution were studied experimentally under the above conditions. The results show that: 1. The influence of magnetic field on the freezing process of water and aqueous solution 1. The magnetic field can reduce the supercooling of water and aqueous solution to a certain extent. 4.6Gs, 9Gs, 18Gs, 36Gs, 72Gs magnetic field can reduce the supercooling of water and aqueous solution by 1.62, 1.68, 1.65, 2.23, 2.55 ~C, respectively, compared with the control group; The average size of ice crystals in water and KMnO_4 solution under magnetic field is about 67% and 76% respectively. 2. The effect of magnetic field on the freezing process of onion, carrot, cucumber, squash and other fruits and vegetables. 1. Cell tissue in magnetic field-assisted freezing process. The formation of ice crystals tends to atomize and sand grains, while the shape of ice crystals tends to be larger blades and blocks in the control group. 2. The supercooling degree of the freezing process of fruit and vegetable cells assisted by magnetic field is lower than that of the control group, and the phase transition process is delayed. In general, with the increase of field strength, the amplitude of the decrease of supercooling degree decreases; 3. The time of phase transition process under magnetic field is shortened, and the time of phase transition process of four kinds of fruits and vegetables under five field strengths is shortened compared with the control group, and the degree of shortening increases with the increase of field strength; 4. The author's evaluation of freezing effect of fruits and vegetables cells. The index of "cell two-dimensional retention_" was put forward, and the value of_could be calculated by Auto CAD software. The "cell two-dimensional retention_" of four kinds of fruits and vegetables during freezing process under five kinds of field strength was higher than that of the control group, but the_value of four kinds of fruits and vegetables did not change with field strength. The freezing of water and water solution, fruit and vegetable cells under magnetic field can be concluded that magnetic field can delay the phase transition process, inhibit the formation of ice crystals and better protect the cell structure. The mechanism may be that the additional magnetic moments produced by the diamagnetism of water molecules and their clusters under magnetic field disturb its irregular thermal movement. These effects make the magnetic field-assisted freezing process reduce the damage degree of ice crystals to fruit and vegetable cells compared with the traditional freezing method, and keep the quality and flavor of fruits and vegetables as much as possible in the future. There should be considerable research value and utilization value.
【学位授予单位】：天津商业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：Q274;O441.4
本文编号：2221324
[Abstract]:In recent decades, the rapid development of radio technology has made it penetrate into all aspects of human production and life, and the consequent effect of electromagnetic fields on organisms has gradually attracted people's attention. Although vitrification freezing method has many advantages over traditional phase change freezing method, it is difficult to realize and is not practical. Since most food materials belong to biological materials, we propose to combine electromagnetic biological effects with food freezing and refrigeration. In this paper, the freezing process of onion and other fruit and vegetable cell tissues was studied by using the self-designed Helmholtz coil magnetic field, and the whole freezing process was photographed by Olympus BX51 cryogenic microscope with camera function. The effect of electromagnetic field of the same form and intensity on the shape and size of ice crystal and the effect of magnetic field freezing on cell morphology and size in the process of fruit and vegetable cell transformation were studied. There are two types of magnetic field: direct current magnetic field and alternating current magnetic field, and the magnetic field intensity is 4.6Gs, 9Gs, 18Gs, 36Gs, 72Gs, respectively. In view of the important role of water and aqueous solution in the process of cell freezing and phase transformation, water and 0.9% concentration of KMn O4 solution were studied experimentally under the above conditions. The results show that: 1. The influence of magnetic field on the freezing process of water and aqueous solution 1. The magnetic field can reduce the supercooling of water and aqueous solution to a certain extent. 4.6Gs, 9Gs, 18Gs, 36Gs, 72Gs magnetic field can reduce the supercooling of water and aqueous solution by 1.62, 1.68, 1.65, 2.23, 2.55 ~C, respectively, compared with the control group; The average size of ice crystals in water and KMnO_4 solution under magnetic field is about 67% and 76% respectively. 2. The effect of magnetic field on the freezing process of onion, carrot, cucumber, squash and other fruits and vegetables. 1. Cell tissue in magnetic field-assisted freezing process. The formation of ice crystals tends to atomize and sand grains, while the shape of ice crystals tends to be larger blades and blocks in the control group. 2. The supercooling degree of the freezing process of fruit and vegetable cells assisted by magnetic field is lower than that of the control group, and the phase transition process is delayed. In general, with the increase of field strength, the amplitude of the decrease of supercooling degree decreases; 3. The time of phase transition process under magnetic field is shortened, and the time of phase transition process of four kinds of fruits and vegetables under five field strengths is shortened compared with the control group, and the degree of shortening increases with the increase of field strength; 4. The author's evaluation of freezing effect of fruits and vegetables cells. The index of "cell two-dimensional retention_" was put forward, and the value of_could be calculated by Auto CAD software. The "cell two-dimensional retention_" of four kinds of fruits and vegetables during freezing process under five kinds of field strength was higher than that of the control group, but the_value of four kinds of fruits and vegetables did not change with field strength. The freezing of water and water solution, fruit and vegetable cells under magnetic field can be concluded that magnetic field can delay the phase transition process, inhibit the formation of ice crystals and better protect the cell structure. The mechanism may be that the additional magnetic moments produced by the diamagnetism of water molecules and their clusters under magnetic field disturb its irregular thermal movement. These effects make the magnetic field-assisted freezing process reduce the damage degree of ice crystals to fruit and vegetable cells compared with the traditional freezing method, and keep the quality and flavor of fruits and vegetables as much as possible in the future. There should be considerable research value and utilization value.
【学位授予单位】：天津商业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：Q274;O441.4
【参考文献】
相关期刊论文 前1条
1 刘宝林,华泽钊,任禾盛;玻璃化——冷藏食品业的发展方向[J];制冷与空调;1997年04期
，本文编号：2221324
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