液氮喷淋流态化速冻系统及冷冻性能研究

液氮喷淋流态化速冻新系统是以液氮为冷源,结合液氮喷淋预冻和流态化速冻两种冻结方法于一体的食品速冻装置。本文建立了基于新系统的食品冷冻过程的焓法数学模型,计算了黄瓜片在不同冻结条件下的降温过程和冷冻时间,同时对冻品质量进行了分析。     

西兰花液氮流态化速冻的实验研究及理论分析

流态化技术被广泛应用于各种行业,本文以西兰花为例对液氮喷雾流态化速冻过程的传热机理进行了分析,通过焓法数学模型进行数值计算,求出冻结时间,并与实验结果进行了比较.通过比较得出,在进行数值计算时将西兰花简化为一维模型可以大大简化计算过程,而通过此种方法得出的冷冻时间与实验数据相比,误差是可以接受的.     

食品玻璃化保存的研究进展

简单介绍了玻璃化转变的基本理论,通过阐述玻璃化保存在水产品、速冻水果及速冻面制品中的应用来说明食品玻璃化保存的研究现状,并对目前食品的玻璃化保存所存在的主要问题进行了探讨。     

速冻装置中喷射器的最佳面积比计算与试验研究

１引言液体二氧化碳速冻食品比液氮速冻食品在价格上便宜得多,比传统的速冻方法,其速冻速度快,从而使食品的保鲜效果好,能保持食品内部细胞不受损坏而使原有的质液不会漏失,仍旧保持食品鲜美的风味,另外还有一些其他的优点。在研究二氧化碳速冻技术的过程中,遇到的关键问题是喷射器的设计,即套筒的横截面积与喷咀喷孔的面积之间存在一个最佳的面积比,以满足不同种食品和不同量食品的速冻要求。本文针对喷器结构的设计,从食品的数量和所要求的冷量及液体二氧化碳的致冷剂总质量出发,提出确定喷咀直径及套筒直径的计算模型,从而获…     

近红外分析技术在食品氨基酸检测中应用的研究进展

综述了近红外分析技术在农作物生长及食品加工处理过程中氨基酸检测的应用情况,及其研究进展。对近红外分析食品氨基酸应用中涉及的化学值HPLC检测以及化学计量学方法进行总结,对相关原始文献中的数据、资料和主要观点进行整理和归纳。对氨基酸的HPLC、化学计量学分析方法及其在农作物品质监测、茶叶中氨基酸和茶多酚含量的同时测定、饲料品质鉴定、奶酪火腿肉制品中氨基酸及其他化学成分含量的测定情况进行了综述,分析了方法的优缺点并对近红外分析技术在食品氨基酸检测中应用进行了展望。近红外光谱在氨基酸检测中应用的发展需基于氨基酸高效液相色谱检测的化学值来建立相应的模型,模型传递的问题是目前制约其大范围推广的主要原因。在线分析可以监测从原料到产品的整个反应变化过程,满足食品从生产到销售等领域中品质实时监控的需求,将是今后重要的发展方向。     

溶液蒸发冻结过程中冰体发展的分形模拟研究

根据溶液在蒸发冻结过程中的复杂性以及液面冰体分布的不规则,结合分形有限扩散聚集(DLA)理论,建立了湿度差作用下溶液蒸发冷冻过程中液面冰体生成、发展过程的数学模型,模拟分析了气流湿度差和气流流速对溶液表面冰体生成、发展的影响.结果表明,利用分形方法可以对溶液蒸发冻结过程中冰体的生成发展进行预测,同时也为研究溶液蒸发冻结和冰体生长提供了新的思路和方法.     

模拟生物组织冻结过程实验与分析

冷冻外科中组织冻结过程的分析对手术实施十分重要。本文建立了低温冷刀实验台,在模拟生物组织中进行冷冻实验,测量了冰球内某点的温度变化;并用有限元方法求解了建立在治法基础上的模拟生物组织冻结过程多维数学模型,计算结果与实验值符合较好;用该模型和方法计算了实验条件下冰球内的温度梯度变化和冷刀所需理论冷量;分析了不同的冷刀直径对冻结过程的影响。     

近红外光谱技术在水产品检测中的应用研究进展

水产品富含水分、蛋白质、不饱和脂肪酸与游离氨基酸等,是消费者喜爱的食品之一。然而,其在贮藏过程中由于温度波动或操作不当等因素会引起品质下降,引发一系列的食品安全问题。近红外光谱技术是一种利用物质对光的吸收、散射、反射和透射等特性来确定其成分含量的检测技术。该技术作为食品分析方法之一,在食品领域中应用广泛,可进行从气体到液体,从匀浆到粉末,从固体材料到生物组织等样品的快速精准与定性定量分析,具有快速无损,安全高效,多组分同时测定等特点。主要对常用无损检测技术的特点进行比较分析,对近红外光谱技术的主要工作原理予以说明,综述了该技术在水产品鲜度评价、掺伪分析、质量评估与货架期预测等方面的应用实例与最新研究进展,目前存在的主要问题,提出该技术应在进一步提升水产品检测精度的前提下,通过与各类理化指标的相关性分析、多种检测技术相融合等法来实现全面评价水产品品质的最终目标,以使其在水产品快速检测过程中得到更加广泛的应用。     

超高压杀菌机制研究进展

 食品中微生物是导致食品品质降低的重要因素之一,超高压作为一种灭菌方式已取得了显著的效果。介绍了超高压杀菌基本原理,着重分析了超高压对微生物细胞形态结构、代谢、遗传物质等造成的影响,并展望了超高压在食品工业中的应用前景。     

基于响应面的铝板表面液滴冻结过程的实验研究

本文以铝板表面上液滴冻结过程为研究对象，研究多因素交互作用在液滴冻结过程中的影响规律。基于响应面实验方法，对不同的冷壁表面温度、空气温度、液滴初始温度及液滴体积的液滴冻结过程展开实验研究。结果表明：冷壁表面温度对液滴的冻结时间影响最大，其次是液滴体积和空气温度，而液滴初始温度对液滴冻结时间影响最小。由方差分析可知，冷壁表面温度和液滴体积之间的交互作用对液滴冻结时间表现显著，其他交互项作用不显著。     

Applications of Infrared Spectroscopy to Biochemical,Food, and Agricultural Processes

Abstract

Integrated investigations on infrared spectroscopic characteristics of metabolites and on applications of infrared spectroscopy to foodstuff production, food processing, and tasting are described. As the important metabolites, saccharides, which play very important roles in various functions, located in the central position of the metabolic pathways, were selected, and the spectral features of the saccharides and related materials are discussed. Additionally, the applications of spectral analysis to the monitoring of the enzyme reaction and the sugar metabolic processes, which are the main materials in food processing, are described. Furthermore, the studies on the spectroscopic measurements during the cultivation of agricultural products as foodstuffs and in the tasting as the final quality evaluation of foods are represented. These results suggest that infrared spectroscopy could be very effective for evaluating foodstuff production and the tasting of the processed foods and that the applied topics should provide fundamental information about the spectral behavior of the metabolites and bioproducts.     

不同储藏年份小麦和红豆的红外光谱研究

粮食的陈化鉴定对于食品安全、种子的老化鉴别对于粮食生产安全具有重要意义。本文利用傅里叶变换红外光谱法研究了不同储藏时间的小麦与红豆,结果显示,同一种不同年份产的样品光谱相似,但在吸收强度比方面都存在着差异,随着贮藏时间的增加,两种粮食的红外光谱表现出一些变化规律,对于小麦,吸收强度比A1653/A1023,A1538/A1023,A1080/A1023,A1155/A1023,A1538/A1653随贮藏时间增加而增加;对于红豆,A2928/A3400、A1648/A3400,A1543/A1648,A1401/A1648,A1055/A1648随着贮藏时间的增加而呈下降趋势。这些比值的变化说明两种粮食在贮藏过程中,蛋白质、多糖结构发生了变化。红外光谱方法在粮食陈化鉴定方面具有方便、快速的优点。     

海南主要地域生咖啡豆挥发性化学成分对比研究

采用固相微萃取-气相色谱-质谱法(SPME-GC-MS)分析海南万宁地区咖啡豆和澄迈地区咖啡豆中挥发性化学组分,通过谱库检索、保留指数对化合物定性,比较两种咖啡豆之间差异。实验结果表明：万宁地区咖啡检出化合物种类91种,澄迈地区咖啡检出106种化合物,有66种相同的化合物,相同组分为75.52%。相同化合物中万宁地区咖啡占总含量的89.86%,澄迈地区咖啡占总含量的85.70%。     

Magnesium enrichment and distribution in plants

Food products enriched with stable isotopes are used in nutrition to study the metabolic fate of nutrients in humans. This study reports on the labeling of green beans, white beans, soybeans and wheat with a stable isotope of magnesium (25Mg) obtained in greenhouse conditions for further studies on magnesium bioavailability. Soybean and green bean are the most efficient plant species to obtain large amounts of edible parts rapidly with a minimum loss of labeled Mg in other parts of the plants. The results obtained showed that a relatively high percentage of the magnesium found in seeds (grains/beans) can come from the redistribution of magnesium previously accumulated in other organs.     

Procyanidins are potent inhibitors of LOX-1: a new player in the French Paradox

Lectin-like oxidized LDL receptor-1 (LOX-1) is an endothelial receptor for oxidized LDL (oxLDL) and plays multiple roles in the development of cardiovascular diseases. We screened more than 400 foodstuff extracts for identifying materials that inhibit oxLDL binding to LOX-1. Results showed that 52 extracts inhibited LOX-1 by more than 70% in cell-free assays. Subsequent cell-based assays revealed that a variety of foodstuffs known to be rich in procyanidins such as grape seed extracts and apple polyphenols, potently inhibited oxLDL uptake in Chinese hamster ovary (CHO) cells expressing LOX-1. Indeed, purified procyanidins significantly inhibited oxLDL binding to LOX-1 while other ingredients of apple polyphenols did not. Moreover, chronic administration of oligomeric procyanidins suppressed lipid accumulation in vascular wall in hypertensive rats fed with high fat diet. These results suggest that procyanidins are LOX-1 inhibitors and LOX-1 inhibition might be a possible underlying mechanism of the well-known vascular protective effects of red wine, the French Paradox.     

Thawing of frozen vegetables observed by a small dedicated MRI for food research

The thawing process for boiled and frozen edible vegetables was traced by a dedicated MRI for food research. The MRI system is small, with a 1.0-T static magnetic field, and can be placed in an ordinary research room with a light air conditioner. Images of green soybeans, broad beans, okra, asparagus and taro were measured by the spin-echo method (echo time=7 ms) with 0.1 or 0.2 s and 1 s repetition times. The images appeared along with the thawing time, and signals uniformly covered the sliced plane of the samples in the thawed condition. Information about the thawing process and tissue structures of the materials was obtained during transit thawing conditions. The thawing kinetics were examined with increased signal intensity, which were divided into two types. The signal increased linearly and saturated for okra and asparagus but exhibited convex curves for soybeans, broad beans and taro. The small MRI was stable, its handling was simple, and the internal structures of food materials could be accurately identified, although the grey-scale of the images was insufficient for determining precise textural fluctuations of tissue organization. We conclude that the devised MRI is useful for examining the quality of frozen foods and for developmental research into frozen foods.     

Application of power ultrasound in freezing and thawing Processes: Effect on process efficiency and product quality

Freezing is one of the most efficient preservation approaches applied to food products and thawing is the reverse process of freezing. However, traditional freezing / thawing methods have low process efficiency. The application of ultrasound is a potential supplementary technique to improve the performance of both freezing and thawing processes of foods. Application of power ultrasound is able to better maintain the microstructure, reduce drip loss, decrease color and texture changes and retain some natural nutrients of foods during freezing. Meanwhile, quality improvement is also observed in food items thawed by ultrasound-assisted thawing methods. The fundamentals and the influences of ultrasound on the freezing and thawing processes of foods are demonstrated in this review article, from the aspects of efficiency enhancement and quality improvement.     

20种代表性主产区蚕豆样品矿物元素含量及其与烹煮品质的相关性分析

探索矿物元素对蚕豆的烹煮加工适用性影响,本研究选取全国各主产区的20种主要栽培蚕豆,采用ICP-MS方法对子叶和种皮中11种矿物元素进行测定,并对蚕豆的灰分和矿物元素含量与烹煮品质指标进行相关性分析,结果显示蚕豆子叶和种皮中矿质元素含量都存在显著差异,矿物元素含量与蚕豆烹煮品质具有一定的相关性,子叶中矿物元素对于烹煮指标的影响由大至小依次为铝、镁、锌、锰、矿物质总量、灰分含量、磷、铜、钾、硒;种皮中的矿物质含量对烹煮指标的影响依次为镁、铜、钙、铝、钾、矿物质总量。     

Using elemental profiles and stable isotopes to trace the origin of green coffee beans on the global market

A broad elemental profile incorporating 54 elements (Li, Be, B, Na, Mg, Al, P, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Rb, Sr, Y, Mo, Pd, Ag, Cd, Sn, Sb, Te, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Er, Tm, Yb, Re, Ir, Pt, Au, Hg, Tl, Pb, Bi and U) in combination with δ(2) H, δ(13) C, δ(15) N and δ(18) O was used to characterise the composition of 62 green arabica (Coffea arabica) and robusta (Coffea canephora) coffee beans grown in South and Central America, Africa and Asia, the four most internationally renowned areas of production. The δ(2) H, Mg, Fe, Co and Ni content made it possible to correctly assign 95% of green coffee beans to the appropriate variety. Canonical discriminant analysis, performed using δ(13) C, δ(15) N, δ(18) O, Li, Mg, P, K, Mn, Co, Cu, Se, Y, Mo, Cd, La and Ce correctly traced the origin of 98% of coffee beans. Copyright ? 2012 John Wiley & Sons, Ltd.     

Effects of multi-frequency ultrasound on the freezing rates,quality properties and structural characteristics of cultured large yellow croaker (Larimichthys crocea)

This research evaluated the effects of multi-frequency ultrasound assisted freezing (UAF) on the freezing rate, structural characteristics, and quality properties of cultured large yellow croaker. The freezing effects with triple ultrasound-assisted freezing (TUF) at 20, 28 and 40 kHz under 175 W was more obvious than that of single ultrasound-assisted freezing (SUF) at 20 kHz and dual ultrasound-assisted freezing (DUF) at 20 and 28 kHz. The results showed that UAF significantly increased the freezing rate and better preserved the quality of frozen large yellow croaker samples. Specifically, the quality parameters of the TUF-treated samples were closer to those of the fresh samples, with greater texture characteristics, a larger water holding capacity (lower thawing loss and cooking loss), lower K values and lower thiobarbituric acid reactive substances values. Light microscopy observation images revealed that the ice crystals formed by TUF were fine and evenly distributed, resulting in less damage to the frozen large yellow croaker samples. Therefore, multi-frequency UAF could improve the quality properties of the large yellow croaker samples.