【摘要】：近幾十年來,無線電技術(shù)的飛速發(fā)展使其滲透到人類生產(chǎn)生活的各個方面,隨之而來的電磁場對生物體的影響作用逐漸為人們所關(guān)注,有關(guān)電磁生物效應(yīng)的研究指出電磁場對生物的多項生理活動中具有影響作用。而在食品低溫保存領(lǐng)域,傳統(tǒng)的低溫凍結(jié)保存方式對食品品質(zhì)會造成損害,玻璃化凍結(jié)方式比起傳統(tǒng)相變凍結(jié)過程雖然具有種種優(yōu)勢,但實現(xiàn)難度過大、實際操作性不強。鑒于食品材料大多屬于生物材料,因此我們提出將電磁生物效應(yīng)和食品冷凍冷藏相結(jié)合,探討電磁場對食品材料凍結(jié)過程中相變階段的作用。本文利用自主設(shè)計的亥姆霍茲線圈磁場作用于洋蔥等果蔬細(xì)胞組織的凍結(jié)過程,并在此過程中利用帶攝像功能的Olympus BX51低溫顯微鏡對凍結(jié)過程進(jìn)行全程顯微拍攝,旨在探究不同形式和場強的電磁場對于果蔬細(xì)胞相變過程中冰晶形狀和大小的作用以及磁場凍結(jié)方式對細(xì)胞形態(tài)和大小的影響。實驗采用Linkam BCS196低溫臺以液氮供冷的方式對果蔬細(xì)胞組織進(jìn)行凍結(jié),其降溫過程溫度精度可達(dá)0.01℃;實驗所采用的磁場形式有:直流磁場和交流磁場兩種,磁場強度分別有:4.6Gs、9Gs、18Gs、36Gs、72Gs五組;鑒于水及水溶液在細(xì)胞凍結(jié)相變過程中的重要作用,本文還對水及0.9%濃度KMn O4溶液在上述條件下進(jìn)行了實驗研究。通過以上實驗我們獲取了大量的圖片數(shù)據(jù)。研究發(fā)現(xiàn):一.磁場對水及水溶液凍結(jié)過程的影響1.凍結(jié)過程中磁場的介入在一定程度上可以降低水及水溶液的過冷度。4.6Gs、9Gs、18Gs、36Gs、72Gs五組磁場作用下相比對照組使得過冷度分別降低了1.62℃、1.68℃、1.65℃、2.23℃、2.55℃;2.從統(tǒng)計規(guī)律來看,相變過程中冰晶大小相比對照組要細(xì)小,其中水和KMn O4溶液在磁場作用下凍結(jié)過程冰晶平均大小分別約為對照組的67%和76%。二.磁場對洋蔥、胡蘿卜、黃瓜、西葫蘆等果蔬凍結(jié)過程的影響1.磁場輔助凍結(jié)過程中細(xì)胞組織在相變過程中生成的冰晶趨向于霧化、沙�；�,而對照組冰晶形狀則多趨向于偏大的刀片狀和塊狀;2.磁場輔助的果蔬細(xì)胞凍結(jié)過程過冷度相比對照組要低,相變過程被推遲。其中5種場強作用下4種果蔬凍結(jié)過程過冷度相對于對照組均有所降低;總體來看,隨著場強增大過冷度降低的幅度減小;3.磁場作用下相變過程時間縮短,其中5種場強作用下4種果蔬的相變過程時間相對于對照組均有所縮短,且縮短的程度隨場強增大而增大;4.作者在對果蔬細(xì)胞凍結(jié)效果評價方面提出“細(xì)胞二維保持率ζ”這一指標(biāo),并可利用Auto CAD軟件對顯微圖像進(jìn)行數(shù)據(jù)計算得出ζ值,其中4種果蔬在5種場強作用下凍結(jié)過程的“細(xì)胞二維保持率ζ”均比對照組高,但四種果蔬的ζ值隨場強變化規(guī)律并不一致。綜上可知,通過對水及水溶液、果蔬細(xì)胞在磁場作用下凍結(jié)的研究可以得出磁場有推遲相變過程、抑制冰晶形成以及更好地保護(hù)細(xì)胞結(jié)構(gòu)的作用,其機理可能是磁場作用下水分子及其團簇的抗磁性所產(chǎn)生的附加磁矩擾亂了它本身的無規(guī)則熱運動從而造成了相變過程成核勢壘增大、流動性降低最終導(dǎo)致過冷度降低、冰晶尺寸減小等作用。以上作用使得磁場輔助凍結(jié)過程相比傳統(tǒng)的冷凍冷藏方式具有減小凍結(jié)過程冰晶對果蔬細(xì)胞破壞程度、盡可能保持果蔬品質(zhì)和風(fēng)味的作用,在未來應(yīng)該會有可觀的研究價值和利用價值。
[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.
【學(xué)位授予單位】：天津商業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：Q274;O441.4

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相關(guān)期刊論文 前1條

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本文編號：2221324