不同干燥方式对蛋清粉蛋白质凝胶特性及结构的影响

为了探讨不同干燥方式下的鸡蛋清蛋白凝胶特性与结构的变化和相关性,采用热风干燥法(hot air drying,HD)、喷雾干燥法(spray drying,SD)和冷冻干燥法(freeze drying,FD)对鸡蛋清进行干燥处理,测定产品的凝胶特性及结构。结果表明,SD和HD较FD蛋清粉凝胶硬度分别提高了49. 47%、23. 87%; SD蛋白凝胶的失水率较FD降低了20. 3%(P <0. 05);分析L*为FD> HD> SD; SD和HD蛋清粉表面巯基含量显著高于FD; SD蛋清粉的变性温度比HD和LD略有升高; 3种样品在340 nm处荧光峰强度为FD> SD> HD; 3种样品中SD蛋清粉蛋白酰胺Ⅰ带α-螺旋比例最小,说明SD对蛋粉的二级结构影响更大,且SD凝胶基质密度最大。SD促使蛋清蛋白发生一定程度的聚集,可更好地改善其凝胶特性,为鸡蛋清粉的深加工提供依据。     

不同喷雾干燥入口温度下鸡蛋清差异蛋白质组学分析

采用iTRAQ技术对蛋清蛋白进行鉴定和生物信息学分析,探讨蛋清蛋白在不同干燥入口温度(140,160,180℃)下差异蛋白质的分布、功能及作用机制。结果表明:与140℃对照组相比,在蛋清喷雾干燥过程中的两个温度点160,180℃分别鉴定出差异蛋白质41,46种(差异倍数1.2,P0.05)。GO功能注释分析了不同干燥入口温度的差异蛋白主要参与的生物过程为细胞过程、生物调节和结合作用。KEGG富集分析得出6个显著变化的蛋白被归类为代谢途径,显著变化的差异蛋白则在溶酶体途径中富集。此外,在差异蛋白中筛选出4种蛋白质在喷雾干燥过程中丰度变化显著,分别是卵白蛋白相关蛋白Y、卵白蛋白前体、卵类黏蛋白亚型X2及卵类黏蛋白亚型1前体。     

干燥方式对四角蛤蜊酶解物功能特性和 抗氧化活性的影响

目的比较不同干燥方式对四角蛤蜊木瓜蛋白酶酶解物功能特性和抗氧化活性的影响。方法采用冷冻干燥和喷雾干燥2种方式对四角蛤蜊木瓜蛋白酶酶解物进行干燥处理,比较其功能特性和抗氧化活性。结果冷冻干燥(freezing drying,FD)组的蛋白含量(49.56%)高于喷雾干燥(spray drying,SD)组(44.31%),2组均含有17种氨基酸,总氨基酸含量之间无显著性差异。两者均具有一定的抗氧化能力,FD组的DPPH?清除能力和还原能力均优于SD组,其IC50和AC0.5值分别为3.02、4.52 mg/mL和3.55、4.03 mg/mL。FD组和SD组颜色差异显著,且FD组的溶解性、起泡性和泡沫稳定性均好于SD组。结论 FD组的功能特性和抗氧化活性均优于SD组,四角蛤蜊酶解物采用真空冷冻干燥效果更好。     

超声辅助喷雾干燥对蛋清蛋白热聚集及凝胶特性的影响

为探究超声辅助喷雾干燥（ultrasonic-spray drying,U-SD）对蛋清蛋白的热聚集及凝胶品质的影响,以喷雾干燥（spray drying,SD）、真空冷冻干燥（vacuum freeze drying,FD）为对照,对所制备的蛋清粉凝胶的分子分布、结构和流变学性能、持水性、质构特性等进行测定。结果表明：超声预处理使蛋白质发生了大分子聚集;蛋清蛋白主要表现为黏弹性流体性质;U-SD蛋清蛋白的二级结构含量中α-螺旋与β-折叠含量均稍有增加;U-SD蛋清粉的凝胶硬度最大,其中弹性、咀嚼性和回弹性均显著大于其他组（P<0.05）,失水率显著降低（P<0.05）,表现出更好的凝胶特性;荧光显微镜证实超声辅助处理可以促进蛋清蛋白发生强烈的聚集。     

不同干燥方式对面片微观结构及品质的比较

本文研究了面片的热风干燥(Hotairdrying,HAD)、真空冷冻干燥(freeze-drying,FD)、微波干燥(microwavedry,MD)、微波真空干燥(Microwave vacuum drying,MVD)和热风-微波联合干燥(hot air followed by microwave drying,HAD+MD)五种不同干燥方法及其对面片物理特性和微观结构的影响。通过以上研究表明:不同干燥速率为MVD>MD>HAD+MD>HAD>FD;面片复水率为FD>MVD>MD>HAD+MD>HAD;面片总色差值FD面片和MVD面片最低并无差异性显著(p>0.05),HAD总色差值最高,为19.56,面片色泽较差。HAD+MD和MD面片总色差值无差异性显著(p>0.05)。面片复水4 min后质构测定发现MD、MVD组延展性最好,分别为81.58 g/sec、72.58 g/sec,FD组剪切力各指标都表现较差,HAD组硬度和咀嚼性较大,分别为1652.88 g、5294.77g.sec。面片扫描电镜观察中,FD面片和MVD面片均观察到均匀密集的孔隙结构,MD面片和HAD+MD面片有明显不均匀孔隙结构,而HAD面片几乎观察不到孔隙结构。各干燥方式对面片的感官评价中FD面片总体评价最佳,MVD、MD面片其次,HAD+MD,HAD面片感官评分最差。综合看来,MVD干燥可以作为开发新疆汤饭产品中面片的适合脱水方式。     

非标记定量蛋白质组学研究干燥方式对牡丹花差异蛋白质的影响

在蛋白质水平上,研究干燥方法（真空冷冻干燥、热风干燥、自然干燥）对牡丹花瓣的影响及作用机理。采用非标记定量蛋白质组学技术对牡丹花瓣进行蛋白质组学的差异性比较,并对差异蛋白质进行GO（Gene Ontology）、KEGG（Kyoto Encyclopedia of Genes and Genomes）注释富集分析,探讨加工方式对代谢通路的作用机制。结果表明:三组样品共定性1423个蛋白质,定量1349个,占总数94.80%;真空冷冻干燥样品FD、热风干燥样品HD、自然风干样品ZD定量蛋白质分别为1325、677、1085个,三组样品共同的定量蛋白质有656个。与HD比较,ZD显著差异蛋白质77个,上调24个,下调53个;77个显著差异蛋白质GO、KEGG分析表明,蛋白质主要集中在糖酵解/糖异生、丙酮酸代谢、TCA循环、内质网蛋白质加工通路。结论:加工方式对牡丹花蛋白质差异影响显著,该研究首次对采用蛋白质组学方法分析牡丹花差异蛋白的表达变化,为不同加工方法在实践中提供科学依据。     

不同干燥方式对新鲜花生营养成分、理化特性及能耗的影响

为使新鲜花生在干燥后保留更好的品质,采用热风干燥(hot-air drying, HD)、微波干燥(microwave drying, MD)、微波冷冻干燥(microwave vacuum freeze drying, MFD) 3种干燥方式对新鲜花生进行干燥处理,考察不同干燥方式对花生营养成分、理化特性及能耗的影响。结果表明,花生经3种不同干燥方式干燥后,其粗蛋白含量无显著差异,脂肪含量显著降低,氨基酸和脂肪酸含量显著下降(P<0.05)。其中MFD花生的氨基酸、脂肪以及脂肪酸含量显著高于其他2组(P<0.05)。酸价和过氧化值的检测结果表明,MFD花生酸价和过氧化值显著低于其他2组。此外,计算HD、MD和MFD除去1 kg水所消耗的能量,MFD分别比HD和MD增加了0.7×10⁵和1.3×10⁵ kJ/kg。综合分析3种干燥条件下新鲜花生的变化,得出经MFD处理后新鲜花生的氨基酸和脂肪酸的保留量最高、过氧化值和酸价的变化值最低,但较HD和MD而言,其能耗有所增加。综合考虑营养成分、理化特性和能耗,建议MFD作为获得高质量干燥...     

干燥方法对洋葱精油提取率及DPPH自由基清除活性的影响

选用热风干燥(AD)、真空冷冻干燥(FD)和微波冷冻干燥(MFD)将新鲜洋葱制成洋葱粉,用蒸馏法提取洋葱精油,对比3种干燥方法下洋葱粉精油的提取率及DPPH自由基清除能力。结果表明,采用微波冷冻干燥洋葱粉提取洋葱精油,得率可达4.57%,且提取时间最短。洋葱精油提取的较优条件为MFD洋葱粉、温浸温度40℃、温浸时间50min,该条件下得到的洋葱精油具有较强的DPPH自由基清除能力。     

干燥方法对茯苓产品显微性状、营养成分及抗氧化活性的影响

选取真空冷冻干燥(FD)、40℃恒温干燥(CD-40)、60℃恒温干燥(CD-60)、100℃恒温干燥(CD-100)、120℃恒温干燥(CD-120)、日晒(SD)、空气能仿生变温干燥(AD)7种方法对茯苓进行干燥,比较干燥后茯苓产品的茯苓菌丝体的显微性状、水溶性多糖含量、水溶性蛋白含量、醇溶性蛋白含量和水提液的抗氧化活性。结果表明:与FD相比,SD、AD的茯苓菌丝体呈疏松排列,CD的茯苓菌丝体呈糊状黏结状态;AD的茯苓产品的抗氧化活性最高;与FD相比,AD的水溶性多糖含量变化不显著、水溶性蛋白极显著增加(P<0.01)、醇溶性蛋白显著减少(P<0.05)。综合分析,AD为最佳的茯苓干燥方法,可解决茯苓无硫加工产业化的需求。     

干燥方式对香菇品质特性及微观结构的影响

为了分析常用的3种干燥方式对香菇干制品品质的影响,以新鲜整香菇为原料,采用三段式微波真空冷冻干燥(three-stage microwave vacuum freeze drying,TS-MVFD)、冷冻干燥(freeze drying,FD)、热风干燥(hot airdrying,HAD)技术干燥加工,探讨不同干燥方式下香菇干制品的干燥特性、营养成分、微观结构,并通过标度法定量分析3种香菇干制品复水熟制后的感官特性。结果表明,香菇脱水至水分质量分数低于13%,TS-MVFD、FD与HAD的干燥时间分别为5、14 h和8 h。复水120 min后,TS-MVFD香菇干制品复水比(7.1)明显高于FD(6.0)、HAD(4.4)样品;复重系数(91.40%)、菌盖色泽和总糖(60.21 g/100 g)、粗多糖(7.41 g/100 g)、游离氨基酸(3.44 g/100 g)含量与FD香菇干制品差异不大;FD香菇截面呈多孔性的蜂窝状网状结构,微孔分布均匀;TS-MVFD香菇微观结构与FD相似,而且微孔孔径稍大;HAD香菇截面结构层叠,细胞壁坍塌严重。复水熟制后,TS-MVFD香菇样品的风味、口感明显优于HAD和FD干燥产品。综上,TS-MVFD是一种有推广价值的香菇干燥方式。     

Color and gelling properties of dried egg white: Effect of drying methods and storage conditions

Dried egg white is extensively used as a food ingredient due to its unique functional properties and extensive shelf life. This study investigated the effect of drying methods and storage conditions on the color and gelling properties of dried egg white. Egg white was dried with two drying methods; freeze drying and hot-air drying, then stored at 25 and 40°C for 4 months. The result showed that the color of hot-air-dried egg white, especially after storage at 40°C, was darker yellow than for freeze-dried egg whites. The gelling properties of both samples were altered during storage, however, substantial changes in the gelling properties were found in the gel made from stored hot-air-dried egg white. A decrease in the enthalpy of protein denaturation that indicated a partially unfolded protein conformation, an increase in exposed sulfhydryl and a decrease in the total sulfhydryl contents were found, especially in stored samples of hot-air-dried egg whites. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis pattern of proteins in the stored samples showed protein aggregation, and this was related to the increased glass transition temperature. This study revealed that drying egg white using hot-air drying and storage especially at high temperature induced changes in their color and protein conformation. These have contributed to protein aggregation which affected dried egg white’s gel properties.     

Comparison of four drying methods for re-structured mixed potato with apple chips

The effects of microwave-freeze drying (MFD), freeze drying (FD), microwave vacuum drying (MVD) and vacuum drying (VD) on texture, color, rehydration, sensory, microstructure and other quality parameters of re-structured chips made by blending apple with potato were studied. MFD chips had the best quality and these products were preferred by consumers. The drying time for MFD was lower than that for FD. The drying time for MVD was the shortest and the energy consumption was also the lowest. Microwave drying not only reduces the drying time but also improves the quality of dried products. Both MFD and MVD techniques are found to be suitable for production of re-structured chips of varying grades.     

喷雾冷冻干燥对鸡蛋清蛋白结构和特性的影响

为了探究喷雾冷冻干燥(Spray freeze drying,SFD)对鸡蛋清蛋白结构及功能特性的影响,将其与喷雾干燥(Spray drying,SD)蛋清粉进行对比,并通过质构仪、差示扫描量热(D S C)、傅里叶变换红外光谱(FT-IR)、扫描电镜(SEM)、低场核磁共振(LF-NMR)等对其结构及特性进行测定。结果表明:SFD粉的变性温度比SD粉低了15.7℃,表面巯基含量低42.40%;SFD粉的α-螺旋和β-折叠结构比例大,分子结构更有序,蛋白聚集程度小,从而使其乳化特性得到改善;SEM分析表明,SFD粉呈大孔隙颗粒网络结构,溶解度增大。两种蛋清粉溶解度随pH的升高均呈先下降后上升的趋势,SFD粉溶解性和乳化性明显高于SD粉(P<0.05),凝肢硬度和束缚水含量显著低于S D粉(P<0.05),保水性差,两者的起泡性无显著差异。综上所述:与SD粉蛋白相比,SFD粉蛋白在结构和部分功能特性方面发生了显著变化,尤其在溶解度和乳化特性方面更具优势。     

Coagulation of Egg White of Soft-Shell Turtle (Pelodiscus Sinensis) at High Pressure or High Temperature

The coagulations of soft-shell turtle egg white at high pressure or at high temperature were investigated and compared to chicken egg white. Unlike chicken egg white, no coagulation of soft-shell turtle egg white was observed after high-pressure processing (HPP; 200–600 MPa) or heating treatment (75°C). Basic amino acids, histidine, lysine, and arginine were present at higher percentages in soft-shell turtle egg white proteins than in chicken egg white proteins. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis showed that the intensities of soft-shell turtle egg white components were balanced, there were more components with high molecular mass in soft-shell turtle egg white, and that aggregates formed in both soft-shell turtle egg white and chicken egg white. This work revealed some differences in soft-shell turtle egg white compositions. The low protein content in egg white was responsible for the non-coagulation of soft-shell turtle egg white in response to high pressure or temperature.     

Instrumental Method for Characterizing Protein Foams

A whipping machine for cream analysis (Cream Tester CTII) was used to foam egg white, milk proteins and soy protein isolate. Foam formation and final rigidity were characterized by the current input to the beating motor. In addition, specific volume, rigidity (compressive strength by Instron) and stability (drainage) of the foams were determined by methods that minimized foam damage during handling. Current input during whipping distinguished fresh vs pasteurized egg white and positively correlated with compressive strength of final egg white foams. Such correlation was not found for milk protein and soy protein isolate foams of lower strength and stability.     

Comparison of Freeze-Drying with Three Different Combinations of Drying Methods and Their Influence on Colour,Texture, Microstructure and Nutrient Retention of Button Mushroom (Agaricus bisporus) Slices

Freeze-drying (FD) and three different combinations of drying methods: freeze-drying combined with hot air drying (FD?+?AD), freeze-drying combined with vacuum drying (FD?+?VD) and freeze-drying combined with microwave vacuum drying (FD?+?MVD) were used to dry button mushroom slices. A comprehensive analysis of dried products was performed on their colour, texture, nutrient retention, microstructure and energy consumption. The results showed that, under conditions of 38 % moisture content changing point, most of the parameters including L* values, a* values, average density and hardness of FD?+?VD and FD?+?MVD samples had no remarkable changes (p?>?0.05) compared with FD samples. However, only FD?+?MVD method can reduce drying time by 35.63 % in comparison of FD method, although all the combination drying methods can reduce the energy consumption. Moreover, FD?+?VD and FD?+?MVD products were better than FD?+?AD products in nutrient retention except that content of vitamin C was comparatively lower during FD?+?MVD process. In conclusion, the FD?+?MVD method has advantages in terms of efficiency and energy saving and could be preferred to produce high-quality products.     

喷雾干燥与冷冻干燥鸡蛋粉特性研究

以鲜鸡蛋为原料,利用喷雾干燥和冷冻干燥技术制备鸡蛋粉,对比2种蛋粉水分含量、水分活度、溶解度、色差、微观结构等理化性质,同时检测起泡性、乳化性,并选用喷雾干燥蛋黄粉制备凝胶探讨功能特性。结果表明:喷雾干燥蛋粉和冷冻干燥的蛋粉水分含量、水分活度、溶解度和色差差异显著(P<0.05),且喷雾干燥蛋粉和冷冻干燥蛋粉起泡性及乳化性均在氯化钠浓度为0.5 g/100 mL时达到最大值;制备凝胶最佳条件为加水量为150%、氯化钠浓度为3%、温度100℃、热处理15 min。此项研究将对蛋粉的应用奠定理论基础。     

不同干燥方式下鮰鱼片的干燥特性及风味变化

本文以鮰鱼为原料,研究了不同干燥方式对鮰鱼干燥特性的影响,并利用气相离子迁移色谱(GasChromatographyIon MobilitySpectrometry,GC-IMS)、电子鼻、电子舌以及氨基酸自动分析仪等技术,对不同干燥方式对鮰鱼片风味进行了分析。结果表明,真空冷冻干燥的鮰鱼片收缩率最小,为5.44%,显著低于其他三种干燥方式(p<0.05),且其复水速率最快,用时最短;热风干燥的鮰鱼片硬度最大,达1929.70 g,与其他三种干燥方式之间有显著性的差异(p<0.05);真空干燥使得鮰鱼片的L*值为最小,a*值和b*值最大,使鮰鱼片呈现焦糖色,而真空冷冻干燥的L*值最高,a*值和b*值最低,使鮰鱼片呈现白色;热风干燥和微波干燥的鮰鱼片气味比较相似,热风干燥和真空干燥处理的鮰鱼片的滋味比较相似,而真空冷冻干燥气味和滋味都区别于其他三种干燥方式;热风干燥和真空冷冻干燥的甜味氨基酸含量分别比苦味氨基酸含量高51.97 mg/g和67.66 mg/g;微波干燥和真空干燥的苦味氨基酸含量分别比甜味氨基酸含量高3.56 mg/g和6.11 mg/g。因此,真空冷冻干燥对鮰鱼片的干燥特性影响最小,且风味有区别于其他三种干燥方式。