超声波辅助冷冻技术作用机理及在冷冻食品中的应用

结晶过程中冰晶的形状、大小及粒径分布和解冻过程中的解冻时间是影响冷冻食品品质的主要因素。超声波辅助冷冻技术作为一项新兴的冷冻技术得到广泛的研究,且研究表明超声波对结晶过程和解冻过程都有积极的影响。本文主要阐述超声波辅助冷冻技术中超声波影响冰晶形成过程的作用机制,主要涉及超声波对晶核形成、冰晶大小和粒径分布的影响;从冷冻食品的冷冻、解冻、无损检测3个方面介绍了超声波在冷冻食品中的应用。     

食品添加剂在冷冻面团技术中的应用

文章简单阐述了冷冻对烘焙食品品质的影响及影响其品质的物理因素,并对食品添加剂在冷冻面团技术中的最新研究与应用进行了重点综述.     

超声辅助冷冻对面筋蛋白二级结构的影响

本文通过对湿面筋蛋白冷冻时间和冷藏过程中二级结构变化的检测,研究超声改善冷冻食品品质的微观作用机制.用激光显微共聚焦拉曼光谱仪测定了不同环境下冷冻,冷藏不同时间的面筋蛋白二级结构,结果显示:传统环境下冷冻的湿面筋蛋白二级结构中的α-螺旋的含量随着冷藏时间的延长逐渐减少,无规卷曲的含量随着冷藏时间的延长逐渐增加;超声环境下冷冻的湿面筋蛋白二级结构随着冷藏时间的延长,其二级结构变化不明显.冻结完成时间的测定表明适宜的功率超声能加速湿面筋蛋白的冷冻过程,显示超声辅助冷冻是改善冷冻食品品质的实用技术.     

萝卜组织孔隙中气体含量对超声辅助浸渍冷冻冻结效果的影响

为了研究组织内部孔隙中气体含量对超声辅助浸渍冷冻冻结效果的影响,加深对空气对超声衰减所造成的影响的了解。本研究以萝卜组织为食品材料模型,采用真空脱气方式对萝卜组织中气体含量进行调节,得到气体含量分别为9.91%、6.46%、4.01%及0的4种萝卜组织,分别在28 kHz、0.33 W/cm2的超声条件下进行超声辅助浸渍冷冻处理,并与常规浸渍冷冻比较。结果表明：与常规浸渍冷冻相比,4种不同气体含量的萝卜组织经过超声辅助浸渍冷冻处理后冻结速率分别提高了20.00%、27.00%、29.00%和33.00%,相变时间分别缩短了16.00%、24.00%、27.00%和31.00%。随着组织中气体含量的降低,超声辅助浸渍冷冻冻结速率得到显著提高（p<0.05）,样品冷冻解冻后的硬度、微观结构及钙离子含量均得到显著的改善（p<0.05）。研究发现组织内部孔隙中气体含量是降低超声辅助浸渍冷冻冻结效果的一大影响因素,脱气处理可以有效改善含气物料超声辅助浸渍冷冻效果。     

高压电场技术在食品加工中的应用研究进展

高压电场技术是一种重要的非热处理技术,由于其效率高、能耗小、无污染、对食品品质几乎无影响,因此在食品加工领域具有广阔的应用前景。目前,该技术主要应用于食品杀菌、食品物料干燥、辅助食品冷冻解冻以及提取食品生物活性物质等方面。本文概述了高压电场技术的基本原理,分析了高压电场对食品中组分的影响,综述了其在食品加工中的应用研究进展及作用机制,并对其应用前景进行了展望,以期为高压电场技术在食品加工中的应用提供理论参考。     

超声波辅助冷冻技术及其在食品中的应用

冷冻是实现食品长期贮藏保鲜的主要手段,冷冻过程中水分的成核与结晶决定着食品冷冻效率和冷冻食品的质量。超声波辅助冷冻作为一种新型的冷冻技术,能在食品冷冻过程中有效地诱导成核并控制结晶过程,提高冷冻食品质量,引起研究者的广泛关注。该文介绍超声波辅助冷冻机制、冷冻效果的影响因素,总结超声波辅助冷冻技术在水产品、果蔬、肉类等食品冷冻加工中的应用研究进展,为超声波辅助冷冻技术在食品领域的深入研究和推广应用提供参考和借鉴。     

提高冷冻水产品品质的新型速冻技术研究进展

水产品因营养价值高,风味口感好,受到人们广泛的喜爱。然而水产品易腐败变质,需要采取一定的措施进行保藏。冷冻保藏技术是水产品最常用的保藏技术,传统的冷冻技术常因冷冻速度慢,形成大的冰晶而导致食品品质下降。近年来,研究者发现一些新兴的速冻技术可以抑制冷冻食品的品质下降。该文对水产品保藏技术中的一些新兴冷冻技术（磁场冷冻技术、电场冷冻技术、超声冷冻技术、高压冷冻技术）的原理,及其在水产品冷冻保藏中的应用进行综述,为人们了解水产品冷冻新技术提供参考。     

超声波辅助冻结对蓝莓渗透传质特性的影响

为探究超声辅助冷冻对蓝莓渗透传质特性的影响,对蓝莓进行空气冻结、浸渍冷冻和超声辅助冷冻3种处理,测定冻结速率、水分分布、钙含量、花色苷含量、细胞膜透性和丙二醛含量等指标。结果表明:与空气冻结及浸渍冷冻相比,超声辅助冷冻显著缩短蓝莓冻结时间,解冻后汁液流失率最低,为8.26%,水分分布状态更接近新鲜蓝莓;超声促进外源钙的渗透迁移,整果和果肉中钙含量显著升高(P﹤0.05);硬度得到更好的保存,然而,花色苷保留率降低40.49%,蓝莓细胞膜透性及丙二醛含量显著降低(P﹤0.05),分别为54.65%,9.15 nmol/g FW。结论:超声辅助冷冻不仅可提高冷冻速率,降低脂膜过氧化,维持细胞膜的完整性,还能促进溶液溶质向食品内渗透。     

新型冷冻和解冻技术在肉类食品中的应用研究进展

冻藏是肉类食品的主要贮藏方式之一,而冷冻和解冻过程是影响冻藏食品品质的重要因素。传统的冷冻和解冻方法耗时长,极易导致营养成分的流失及品质的降低,已不能满足现代食品工业的发展需求。因此,发展能够较好地保持肉类食品品质的新型快速技术具有重要的意义。文中对目前先进的冷冻和解冻技术在肉类食品中的应用研究进行重点综述,分析了各技术现阶段存在的不足和未来的研究趋势,为肉类食品冷冻工业的实际生产提供相关指导。     

冷冻食品货架期研究现状及发展趋势

食品货架期作为反应食品品质及安全性的标识,对它进行研究具有现实意义。文章对冷冻食品货架期进行了全面介绍,并说明了温度对冷冻食品货架期及品质的重要影响。由于冷冻食品的特殊性及冷链物流中存在的问题,在波动温度下对冻品货架期做出预测已成为研究的焦点。本文通过对冷冻食品货架期研究中的3 个重要阶段及目前研究重点的阐述,指出了未来冷冻食品货架期研究的创新点与发展方向。     

Effects of freezing on cell structure of fresh cellular food materials: A review

BackgroundFresh cellular food materials including fruits and vegetables and animal tissues normally consist of fine organized cellular structures. Freezing is a common method to preserve the quality and safety of these cellular foods. However, the formation of ice crystals during food freezing may cause damage to the food microstructure, leading to the deterioration of food quality after thawing.Scope and approachThis review offers current knowledge on freezing damage to cell structure of fresh cellular food materials. Effects of cell structure and water distribution on the texture and sensory properties of fresh cellular foods are presented. Mechanisms of cell structure damages caused by freezing are discussed. Novel methods to control the formation of ice crystals and preserve cell structures are also provided.Key findings and conclusionsThe quality of cellular foods after frozen-thawed is highly correlated with the integrity and viability of tissue cells. The formation of ice crystals, water migration and the inherent characteristics of cell structure are regarded as the main factors affecting the cell structure during freezing. For obtaining better quality of frozen products, further investigation and understanding on freezing damage to cell structure of fresh cellular foods is necessary. It is hoped that the current review will provide more information on improving frozen food quality for the frozen food industry.     

Effect of freezing temperature on the color of frozen salmon

New freezing methods developed with the purpose of improved product quality after thawing can sometimes be difficult to get accepted in the market. The reason for this is the formation of ice crystals that can give the product a temporary color loss and make it less appealing. We have here used microscopy to study ice crystal size as a function of freezing temperature by investigating the voids in the cell tissue left by the ice crystals. We have also investigated how freezing temperature affects the color and the visible absorption spectra of frozen salmon. Freezing temperatures previously determined to be the best for quality after thawing (-40 to -60 °C) were found to cause a substantial loss in perceived color intensity during frozen state. This illustrated the conflict between optimal freezing temperatures with respect to quality after thawing against visual appearance during frozen state. Low freezing temperatures gave many small ice crystals, increased light scattering and an increased absorption level for all wavelengths in the visible region. Increased astaxanthin concentration on the other hand would give higher absorption at 490 nm. The results showed a clear potential of using visible interactance spectroscopy to differentiate between poor product coloration due to lack of pigmentation and temporary color loss due to light scattering by ice crystal. This type of measurements could be a useful tool in the development of new freezing methods and to monitor ice crystal growth during frozen storage. It could also potentially be used by the industry to prove good product quality. PRACTICAL APPLICATION: In this article we have shown that freezing food products at intermediate to low temperatures (-40 to -80 °C) can result in paler color during frozen state, which could affect consumer acceptance. We have also presented a spectroscopic method that can separate between poor product color and temporary color loss due to freezing.     

速冻食品的冰晶形态及辅助冻结方法研究进展

文章简述了食品速冻技术以及不同冻结速度下形成的冰晶形态及观测冰晶的方法,综述了压力辅助冻结、电场辅助冻结以及磁场辅助冻结等技术在近几年的研究进展。直接法能直接观察到冻结过程形成的冰晶,而间接法则是通过观察冻结后冰晶在食品内部留下的间隙来分析冰晶特征。压力辅助冻结能提高过冷度,在压力释放时水分瞬间冻结,使形成的冰晶细小且分布均匀;电场辅助冻结能降低成核温度促使形成更小尺寸的冰晶;磁场辅助冻结能增强氢键抑制冰晶的生长,3种辅助冻结方式有利于提高冷冻食品的品质,具有良好的应用前景。     

影响冷冻面团因素及其品质改良研究进展

冷冻面团技术作为一种面制品加工工艺,具有防止产品老化,便于冷藏和运输等优势,因此在国内外得到广泛应用。然而,在冷冻面团生产和贮藏过程中存在一系列问题,例如：面筋结构完整性丧失、酵母细胞失活以及淀粉结构被破坏等,这些都导致了面制品品质的劣变。本文综述了影响冷冻面团品质的主要因素,总结了提高冷冻面团品质特性的有效方法,改良剂的添加不仅可以提高酵母的耐冻性,而且可以保持面团的流变学特性。基因工程技术修饰可以提高酵母的耐冻性和发酵能力。通过优化冷冻和储存条件,确保酵母的活性和面团的网络结构,使冰晶造成的冻害最小化。此外,新型冷冻技术的应用如超声波辅助冷冻可以在加速冷冻过程的同时生成均匀的冰晶,从而保护面团的网络结构。以期为改善冷冻面团品质以及为开发新型的冷冻面团技术提供理论依据。     

Emerging techniques for assisting and accelerating food freezing processes: A review of recent research progresses

Freezing plays an important role in food preservation and the emergence of rapid freezing technologies can be highly beneficial to the food industry. This paper reviews some novel food freezing technologies, including high-pressure freezing (HPF), ultrasound-assisted freezing (UAF), electrically disturbed freezing (EF) and magnetically disturbed freezing (MF), microwave-assisted freezing (MWF), and osmo-dehydro-freezing (ODF). HPF and UAF can initiate ice nucleation rapidly, leading to uniform distribution of ice crystals and the control of their size and shape. Specifically, the former is focused on increasing the degree of supercooling, whereas the latter aims to decrease it. Direct current electric freezing (DC-EF) and alternating current electric freezing (AC-EF) exhibit different effects on ice nucleation. DC-EF can promote ice nucleation and AC-EF has the opposite effect. Furthermore, ODF has been successfully used for freezing various vegetables and fruit. MWF cannot control the nucleation temperature, but can decrease supercooling degree, thus decreasing the size of ice crystals. The heat and mass transfer processes during ODF have been investigated experimentally and modeled mathematically. More studies should be carried out to understand the effects of these technologies on food freezing process.     

Freezing of meat and aquatic food: Underlying mechanisms and implications on protein oxidation

Over the recent decades,protein oxidation in muscle foods has gained increasing research interests as it is known that protein oxidation can affect eating quality and nutritional value of meat and aquatic products. Protein oxidation occurs during freezing/thawing and frozen storage of muscle foods, leading to irreversible physicochemical changes and impaired quality traits. Controlling oxidative damage to muscle foods during such technological processes requires a deeper understanding of the mechanisms of freezing-induced protein oxidation. This review focus on key physicochemical factors in freezing/thawing and frozen storage of muscle foods, such as formation of ice crystals, freeze concentrating and macromolecular crowding effect, instability of proteins at the ice–water interface, freezer burn, lipid oxidation, and so on. Possible relationships between these physicochemical factors and protein oxidation are thoroughly discussed. In addition, the occurrence of protein oxidation, the impact on eating quality and nutrition, and controlling methods are also briefly reviewed. This review will shed light on the complicated mechanism of protein oxidation in frozen muscle foods.     

Icy affairs: Understanding recent advancements in the freezing and frozen storage of fish

Freezing methods have evolved over the last 30 years. This review states the effect of various freezing methods on the quality of fish and seafood. Freezing temperatures, freezing, and frozen storage temperatures were also analyzed and reviewed. The changes in the ice crystal, protein, and lipid affect the fish quality and nutritional value during freezing and frozen storage. Freezing methods when combined with various additives or preprocessing approaches help improve the efficacy of freezing and frozen storage. Several experimental or emerging methods also have positive effects on the products' quality. According to the metadata reanalysis of quality markers, freshly frozen fish using different freezing methods may vary much in terms of ice diameter, but not others. High pressure freezing or immersion freezing-derived fish retains the best quality through frozen storage. More data are required on freezing methods (electrical-assisted freezing, microwave-assisted freezing, magnetic-assisted freezing, radiofrequency-assisted freezing, and the commercial's application and investment should be considered in the future. This review sheds light on finding a balanced initial shear force during freezing and the use of certain additives to control freezing-related damages. Focusing on ice diameter alone may be futile (e.g., liquid N₂ freezing). Future optimization of technologies should be in a way that several processes along the farm to fork such as freezing, frozen storage, thawing, thermal processing of fish, and even refabrication of food should mutually complement each other's needs to deliver safe and high-quality fish to the consumer's plate, even after a prolonged shelf-life.     

鱼糜冷冻稳定剂的种类及作用机理

鱼糜在冷冻贮藏过程中冰晶的形成是导致其品质降低的根本原因。鉴于现有抗冻剂的安全性和经济性,单纯通过抗冻剂来抑制冰晶形成,或许无法最大程度地提高鱼糜的冻藏品质。与抗冻剂的作用对象不同(控制冰晶形成),冷冻稳定剂可作为现有冷冻保护策略的重要补充,通过增强鱼糜组分的稳定性,以抑制其在冷冻过程中的各种生化反应,从而达到鱼糜冷冻保护最大化。本文首先探讨了鱼糜在冷冻过程中的品质变化规律,重点概述冷冻稳定剂的种类(糖类、蛋白水解物类、胶体类及多酚类)及其冷冻稳定机理,展望鱼糜冷冻保护策略的发展趋势。本文旨在从增强鱼糜主要组分的冻融稳定性角度出发,可作为现有冷冻保护剂的有效补充,以最大程度地提高鱼糜制品的冷冻品质。     

Effects of Weak Oscillating Magnetic Fields on the Freezing of Pork Loin

A number of novel freezing systems have been developed that claim to improve the quality of frozen foods by enhancing supercooling in the food prior to ice nucleation and consequently controlling ice crystal formation. One of these is the Cells Alive System (CAS) produced by ABI of Japan, which applies oscillating magnetic fields (OMF) during freezing. This study was carried out to investigate what effect applying OMF (0.04 to 0.53 mT) during freezing had on the freezing characteristics of pork loin samples when compared to freezing under the same conditions without OMF. Overall, the results of this study clearly indicate that freezing under the OMF conditions used in these experiments had no significant effect on the freezing characteristics of pork, in comparison with freezing under the same conditions without OMF.