微波及其联合杀菌技术在食品中的应用研究进展

微波在食品中的应用已逐渐成为研究热点，但微波作为一种新型食品杀菌技术，特别是和其他杀菌技术联合应用的综述目前还较少。本文通过分析已有的食品微波杀菌技术，包括单微波杀菌技术、微波-巴氏杀菌技术、微波-超声联合杀菌技术、微波-红外杀菌技术、微波-脉冲电场杀菌技术的特点，总结微波及其联合杀菌技术对不同类型食品的杀菌条件和效果，旨在为微波在各类食品杀菌工艺中的应用提供参考。     

微波法提取鼠尾藻多糖的工艺研究

研究采用了微波法提取鼠尾藻多糖,考查了微波辐照时间、微波功率、料液比、超声预处理时间四个因素的影响,并采用正交实验法确定微波提取的最佳工艺。结果表明微波法提取多糖产率为6.5%,其优化工艺条件为:微波辐照时间8 min,微波功率540 W,料液比1∶30,超声时间3 min。经红外光谱得知鼠尾藻多糖的主要组成单糖为吡喃糖。微波法提取鼠尾藻多糖可行,工艺简单,产率令人满意。     

三种药用植物多糖体外抗氧化性对比

本研究以总还原能力、清除羟自由基能力、清除超氧阴离子自由基能力和清除DPPH能力为指标,比较微波提取法和热水浸提法对白芷、白及和桔梗多糖抗氧化性的影响。结果表明:各个提取条件下,4项指标与多糖的浓度呈量效关系,多糖浓度为10 mg/m L时抗氧化能力最强。总还原能力大小依次为水提白及微波白及微波白芷水提白芷微波桔梗水提桔梗;清除羟自由基·OH的能力为:微波桔梗水提桔梗微波白及水提白及微波白芷水提白芷;清除超氧阴离子自由基O_2~-·的能力为:水提白芷微波白芷微波白及微波桔梗水提白及水提桔梗;清除DPPH的能力为:微波桔梗水提桔梗微波白及水提白及微波白芷=水提白芷=0。综合各因素考虑,微波提取法优于热水浸提法,其中白及多糖表现出较好的抗氧化性,在四种指标检测结果中效果显著。     

微波治疗原理简介

微波治疗是临床上一种新的治疗手段 ,其优点是 :设备简单 ,效果明显 ,安全 ,并发症少。本文结合ＯＫＷ微波治疗仪的特点 ,简要介绍微波治疗的一般原理及其在临床上的应用。一、微波的物理特性微波是频率为 30 0～ 30 0 0 0 0ＭＨｚ、波长 1ｍｍ～ 1ｍ的超高频电磁波 ,在微波治疗仪中 ,微波传输特性由微波馈线和辐射器决定 ,优良的辐射器能使传输的微波具有极佳的方向性 ,有相当准确的定位精度。微波的传输是直线传输 ,遇阻产生反射 ,因此辐射器在治疗中起非常关键的作用。微波是属于非电离辐射 ,它不能使化学物质中较弱的氢键断裂 ,也不能使…     

甜荞麦壳原花色素微波辅助提取工艺研究

通过单因素实验和Plackett-Burman设计,研究了乙醇体积分数、微波功率、微波时间、料液比、水浴温度对微波辅助提取甜荞麦壳原花色素的影响,并对甜荞麦壳原花色素微波提取工艺影响因素的显著性进行考察,其中微波时间、乙醇体积分数和微波功率对甜荞麦壳原花色素得率具有显著影响(P0.05)。在此基础上设计三因素三水平响应面分析方法对甜荞麦壳原花色素微波辅助提取工艺进行优化,建立了二次多项式回归方程的预测模型,结果表明:微波辅助提取甜荞麦壳原花色素最佳工艺为:料液比为1∶30 g/m L,乙醇体积分数35%,水浴温度70℃,微波功率280 W,微波提取时间28 s,在此条件下甜荞麦壳原花色素得率为2.21%。     

响应面法优选牡丹果荚中丹皮酚和芍药苷提取工艺的研究

以牡丹果荚为原料,采用响应面分析法对影响微波辅助提取牡丹果荚中芍药苷和丹皮酚的主要因素(料液比、微波功率、微波时间)进行优化。结果表明:微波辅助提取牡丹果荚中的芍药苷及丹皮酚的最佳提取工艺条件为:液料比10∶1、微波功率253 W、微波时间10 min,牡丹果荚芍药苷和丹皮酚的得率分别为2.92、0.91 mg·g-1。与传统提取法相比,微波辅助提取方法不仅提取时间短,原料使用量少,而且提取率高,是一个高效的提取方法。     

微波提取苦荞麦麸皮总黄酮工艺研究

本文对苦荞麦麸皮总黄酮微波提取工艺进行了研究。试验结果表明:微波提取的最佳工艺条件为微波功率中档,微波加热120 s,乙醇浓度80%,料液比1:50,该工艺条件下总黄酮得率达5.51%;与传统提取方法相比,微波提取法具有节省时间、节约能量、提取效率高、控制方便等优点。     

两种方法提取香菇多糖的比较研究

采用正交试验比较研究热水浸提法和微波提取法提取香菇多糖。热水浸提法的最佳工艺为:提取温度70℃、提取时间4h、料液比1∶15,提取率3.243%;微波提取法的最佳工艺为:微波功率560W、微波处理时间60s、料液比1∶10,提取率4.771%。微波提取法效率高、时间短,是理想的香菇多糖提取方法。     

Two Extraction Methods of Lentinan Polysaccharide

采用正交试验比较研究热水浸提法和微波提取法提取香菇多糖.热水浸提法的最佳工艺为:提取温度70℃、提取时间4h、料液比1∶15,提取率3.243 ％;微波提取法的最佳工艺为:微波功率560W、微波处理时间60 s、料液比1∶10,提取率4.771％.微波提取法效率高、时间短,是理想的香菇多糖提取方法.     

微波辅助萃取法提取玄参中哈巴苷和哈巴俄苷的工艺研究

本文研究微波辅助萃取法提取玄参中哈巴苷和哈巴俄苷的最佳工艺条件,应用微波辅助萃取法提取玄参中的哈巴苷和哈巴俄苷,采用高效液相色谱法测定哈巴苷和哈巴俄苷的含量。结果表明微波辅助萃取法提取玄参中哈巴苷和哈巴俄苷的最佳工艺参数:纯水作提取剂、料液比为1∶20、微波温度为50℃、微波时间为30min、微波功率为600 W。在此最佳工艺条件下玄参中哈巴苷和哈巴俄苷的总提取率为1.1172%。     

Vibrational resonances in biological systems at microwave frequencies

Many biological systems can be expected to exhibit resonance behavior involving the mechanical vibration of system elements. The natural frequencies of such resonances will, generally, be in the microwave frequency range. Some of these systems will be coupled to the electromagnetic field by the charge distributions they carry, thus admitting the possibility that microwave exposures may generate physiological effects in man and other species. However, such microwave excitable resonances are expected to be strongly damped by interaction with their aqueous biological environment. Although those dissipation mechanisms have been studied, the limitations on energy transfers that follow from the limited coupling of these resonances to the electromagnetic field have not generally been considered. We show that this coupling must generally be very small and thus the absorbed energy is so strongly limited that such resonances cannot affect biology significantly even if the systems are much less strongly damped than expected from basic dissipation models.     

微波诱变育种研究及应用进展

介绍了微波的生物效应及诱变机理,同时较为系统地介绍了微波诱变在农业、畜牧业及工业育种上的研究进展及成果。此外还对研究中的不足方面进行了阐述,并预测了今后的研究方向。     

Physical plasma in biological solids: a possible mechanism for resonant interactions between low intensity microwaves and biological systems

Observed semiconductor properties of biological material in vitro indicate possible involvement of semiconduction in biological processes. Since in inorganic semiconductors solid-state plasma occurs, it is hypothesized that in organic semiconductors solid-state plasma similarly occurs. Some results of experimental investigation of resonant effects of microwaves in biological systems are considered in the light of that hypothesis. The conditions necessary for the existence of physical plasma in biological solid structures are discussed, and certain parameters of physical plasma in these structures are evaluated. Its is proposed that microwave radiation may support or damp plasma oscillations, thereby stimulating or suppressing biological functions.     

New mechanisms of biological effects of electromagnetic fields

ATP production in mitochondria depends on the nuclear spin and magnetic moment of Mg²⁺ ion in creatine kinase and ATPase. Consequently, the enzymatic synthesis of ATP is an ion-radical process and depends on the external magnetic field and microwave fields that control the spin states of ion-radical pairs and influence the ATP synthesis. The chemical mechanism of ATP synthesis and the origin of biological effects of electromagnetic (microwave) fields are discussed.     

微波生物效应对细胞的影响

综述了当前国内外学者在微波生物效应对细胞的影响这一领域中的研究进展,着重论述了微波辐射对细胞的形态和增殖、细胞的有丝分裂和ＤＮＡ合成、细胞膜的通透性、细胞遗传学及酶的活性等方面的影响,并提出了展望。     

Microwave-specific heating affects gene expression

The effects of low-level microwave radiation on gene expression in Escherichia coli have been examined in a sensitive model. We confirm the previously reported existence of an increase in β-galactosidase expression by microwave radiation—an increase not duplicated by bulk heating. However, the effect was not frequency dependent and appeared to be due to heating effects peculiar to microwaves. These results indicate that small thermal gradients may be a source of biological effects of non-ionizing radiation.     

Effects of Pulsed 2.856 GHz Microwave Exposure on BM-MSCs Isolated from C57BL/6 Mice

The increasing use of microwave devices over recent years has meant the bioeffects of microwave exposure have been widely investigated and reported. However the exact biological fate of bone marrow MSCs (BM-MSCs) after microwave radiation remains unknown. In this study, the potential cytotoxicity on MSC proliferation, apoptosis, cell cycle, and in vitro differentiation were assayed following 2.856 GHz microwave exposure at a specific absorption rate (SAR) of 4 W/kg. Importantly, our findings indicated no significant changes in cell viability, cell division and apoptosis after microwave treatment. Furthermore, we detected no significant effects on the differentiation ability of these cells in vitro, with the exception of reduction in mRNA expression levels of osteopontin (OPN) and osteocalcin (OCN). These findings suggest that microwave treatment at a SAR of 4 W/kg has undefined adverse effects on BM-MSCs. However, the reduced-expression of proteins related to osteogenic differentiation suggests that microwave can the influence at the mRNA expression genetic level.     

Metabolic changes in cells under electromagnetic radiation of mobile communication systems

Review is devoted to the analysis of biological effects of microwaves. The results of last years' researches indicated the potential risks of long-term low-level microwaves exposure for human health. The analysis of metabolic changes in living cells under the exposure of microwaves from mobile communication systems indicates that this factor is stressful for cells. Among the reproducible effects of low-level microwave radiation are overexpression of heat shock proteins, an increase of reactive oxygen species level, an increase of intracellular Ca2+, damage of DNA, inhibition of DNA reparation, and induction of apoptosis. Extracellular-signal-regulated kinases ERK and stress-related kinases p38MAPK are involved in metabolic changes. Analysis of current data suggests that the concept of exceptionally thermal mechanism of biological effects of microwaves is not correct. In turn, this raises the question of the need to revaluation of modern electromagnetic standards based on thermal effects of non-ionizing radiation on biological systems.     

Significance of microthermal effects derived from low level UHF-microwave irradiation of the head: indirect caloric vestibular stimulation

Reports of behavioral and clinical changes following weak microwave irradiation, though not fully documented, are of sufficient moment to require examination of each possible biological consequence of low level exposure, particularly with respect to the central nervous system. In this report the hypothesis that significant cytological microthermal effects are induced by low intensity microwave fields (10 mW/cm² incident power density) is examined. An estimate of the upper bound on the thermal effects thus produced is made, showing the thermal variations to be no larger than those endogenous to neural tissue. A similar analysis of microthermal effects within the vestibulo-cochlear apparatus, however, suggests the more limited hypothesis that this structure is responsive to weak, absorbed microwave energy. An estimate of the temperature gradients, hence, local fluid density changes within the labyrinth supports the existence of detectable intralabyrinthine convective forces at incident power densities as low as 15–20 mW/cm². This suggests (i) that microwave induced vestibular effects may provide a cue to alert personnel to significant acute microwave exposure, (ii) that reports of behavioral and/or clinical reactivity to low level microwave exposure may derive from such a benign but potentially useful interaction and (iii) that geometric peculiarities of the vestibulo-cochlear apparatus may result in markedly enhanced microwave-labyrinthine coupling at particular radiation wavelengths.     

The effect of 2450-MHz microwave radiation during microtubular polymerization in vitro

Exposure to 2450-MHz (cw) microwave radiation causes inhibition of cell division in intact cells and varied in vivo biological effects in both avian and mammalian species. Because these reported effects may result from alterations in the dynamics of microtubule formation, we studied the effects of simultaneous microwave exposure (2450 MHz, cw) during each of the three critical stages of the intracellar polymerization cycle. In addition, using circular dichroism spectroscopy, we studied the effect of microwave irradiation on the secondary structure of purified tubulin polypeptides. These studies were accomplished using specially constructed exposure systems that permit the continuous recording of turbidometric or circular dichroism measurements during simultaneous exposure to microwaves. The baseline turbidity of microtubular protein did not change under the influence of microwave radiation (20 or 200 mW/g SAR) and irradiation had no effect on the light-scattering properties of the depolymerized protein. EGTA-induced polymerization and cold-induced depolymerization patterns were also similar for both control and microwave-irradiated samples. The circular dichroism spectrum of purified tubulin also did not appear to be influenced by microwave irradiation, indicating a lack of effect on the protein secondary structure. The data suggest that the cellular effects of microwaves are not due to changes in microtubular proteins or their rate of polymerization.