谷朊粉及其主要组分对果糖吸湿的抑制作用

为改善果糖因其强吸湿性而导致的结块和潮解现象,通过绘制吸湿曲线,吸湿等温线,宏观形态分析,接触角测定以及低场核磁等表征手段,考察谷朊粉（Wheat Gluten,WG）添加量对果糖冻干品吸湿特性的影响,并比较了谷朊粉中两种主要成分：麦醇溶蛋白和麦谷蛋白的作用差异。结果表明,谷朊粉显著降低了冻干果糖样品的平衡吸湿率（Equilibrium Moisture Content,EMC）,在25 ℃、75%相对湿度下果糖与谷朊粉比例为10:0、3:7、2:8的EMC分别为36.33%、16.00%、14.61%;随着谷朊粉比例的增加,样品的结块程度减弱,接触角由11.3 °增大到94.8 °。Peleg模型可以准确描述果糖-蛋白体系的水分吸附过程;相较于麦醇溶蛋白,添加麦谷蛋白的样品EMC更低,结块量更小,且麦谷蛋白的接触角（88.2 °）大于麦醇溶蛋白（64.6 °）;低场核磁结果显示,与麦醇溶蛋白相比,麦谷蛋白对降低水分自由度产生了更有效的影响。以上结果表明,谷朊粉及其主要组分对果糖的吸湿有显著的抑制作用,相较于麦醇溶蛋白,麦谷蛋白抑湿效果更突出。     

紫苏面包粉的制备及其粉质特性分析

以面包专用粉为主料,添加紫苏油粕粉制备具有紫苏风味的紫苏面包粉,并添加适量的谷朊粉改善其粉质特性,采用粉质仪检测,以吸水量、形成时间、稳定时间和质量指数为考核指标,研究紫苏油粕粉和谷朊粉添加量对紫苏面包粉品质的影响。结果表明,紫苏油粕粉添加量10%,谷朊粉添加7%时,紫苏面包粉粉质最优:吸水量60.9%,形成时间10 min20s,稳定时间12min 36s,质量指数140。     

谷朊粉对糙米粉面团性质影响研究

研究了谷朊粉添加量对糙米粉面团性质的影响,主要包括粉质特性、热机械性质、流变学性质、微观结构等。结果表明:随着谷朊粉添加量增大,面团的吸水率、形成时间、稳定时间、淀粉衰减值和回生程度均在逐渐增长,蛋白弱化度在逐渐降低。糙米粉面团的弹性模量和粘性模量均在增大,且弹性模量大于粘性模量。扫描电镜结果显示:随着谷朊粉添加量增大,面团的网络结构越来越明显,淀粉颗粒镶嵌在蛋白形成的网络结构中,增加了面团的弹性及变形的阻力。     

谷朊粉对面包基础粉品质特性的影响

探讨不同添加量的谷朊粉对面包基础粉蛋白质的品质、流变特性及面包烘焙品质的影响。结果表明:谷朊粉可以明显增加面包基础粉的湿面筋含量、沉淀值和蛋白质含量,强化其流变学特性,有效改善面包烘焙品质,增大面包比容和高径比并改善其弹性和硬度。当谷朊粉添加量为10%时,面包烘焙品质最好。     

谷朊粉在面包专用粉中应用研究

研究了不同添加量的谷朊粉对面包粉蛋白质含量、湿面筋、灰分以及粉质曲线和吹泡曲线的影响,进行了谷朊粉不同添加量的面包焙烤试验,找出谷朊粉最经济的添加量。     

谷朊粉对面条质构及微观结构的影响

研究谷朊粉对面条的色泽、蒸煮特性、质构特性的影响,并通过扫描电子显微镜观察面条微观结构的变化,结合感官评价,以得出最优添加量。结果表明:添加谷朊粉会降低面条的亮度;面条的硬度和咀嚼性随谷朊粉的添加而增大,分别从8746.22 g、0.79上升到10803.26 g、0.92,当谷朊粉的添加量≥1%时,面条的回复性无显著变化(P0.05),相比于1%和4%的谷朊粉添加量,2%的添加量使面条的弹性、胶着性、黏聚性下降;SEM图显示适当添加谷朊粉可以改善面条的均一性,而4%的添加量使面条内部结构出现断裂;另外,谷朊粉的添加量为1%时,感官评价最优。     

谷朊粉对速冻馒头品质影响的研究

研究了谷朊粉的添加量对速冻馒头比容、柔软度、总评分等品质的影响。实验结果表明：随着谷朊粉添加量的变化,速冻馒头的比容、柔软度、总评分也发生变化。合理掌握谷朊粉的添加量可以使速冻馒头获得较好感官品质、比容、柔软度、总评分。     

谷朊粉对我国小麦粉品质改良的研究

分别向６种国产小麦粉中添加一定比例的法国和国产两种谷朊粉,研究添加前后所面粉品质性状,包括粉质参数和面包烘焙品质的变化。结果添加谷朊粉能够改善国产小麦粉的品质,其改良效果受到添加量、谷朊粉质量以及小麦粉自身,品质等因素的影响。并探讨了在国产小麦粉中添加谷朊粉生产高级面包专用粉的可能性。     

谷朊粉对苦荞小麦混合粉流变学特性影响研究

该研究首先利用实验磨进行苦荞制粉,然后以苦荞小麦混合粉(20:80)为对象,参照国际标准分析方法,系统分析谷朊粉对混合粉流变学特性影响。结果表明,随着谷朊粉添加量增加,混合粉粉质特性、拉伸特性及烘焙特性得到不同程度改善;在该试验条件下,谷朊粉最佳添加量为4%。     

谷朊粉对饺子粉品质改良效果的研究

为了研究谷朊粉对饺子粉品质的改良效果,筛选适宜的添加量,分析了添加不同剂量谷朊粉小麦粉的粉质参数、拉伸参数以及生饺子皮的色泽、质构特性、蒸煮干物质失落率和熟饺子皮的质构特性。结果表明,随着谷朊粉添加量的增加,面团的稳定时间、评价值、拉伸能量、拉伸阻力、最大拉伸阻力、拉伸比例、最大拉伸比例以及穿破生饺子皮所作的功均不断增加,弱化度和生饺子皮亮度逐渐降低。饺子皮的综合评分显示,当谷朊粉添加量为9%时制作的饺子皮品质最好。因此,谷朊粉对饺子粉品质具有明显的改善作用,其最佳添加量为9%。     

冬枣粉吸湿的色泽、热力学特性及糖物质基础分析

为充分了解枣粉吸湿过程中的水分吸附特性,本研究采用静态称量法,分别测量枣粉在温度20、30、40 ℃,水分活度0.112～0.946下的吸湿情况,探究超微粉碎前后枣粉吸湿色泽的变化、吸附等温线、热力学性质及糖物质基础。结果表明,枣粉吸湿后褐变现象严重,其吸附等温线是III型,Peleg模型最适合描述枣粉的吸附等温线（平均相对预测误差E＜5%）。净等量吸附热和微分熵随着枣粉平衡水分含量（干基,下同）的增加呈指数降低,且超微粉低于普通粉。普通粉和超微粉的绝对安全水分含量分别为0.237 5、0.223 5 g/g。普通粉和超微粉的水分吸附过程均满足熵-焓补偿理论,其吉布斯自由能分别是1 152.80、1 184.22 J/mol,该过程是一个焓驱动的非自发反应。单糖吸湿对照实验结果表明枣粉中吸湿的主要糖种类为果糖。本研究旨在为枣粉的加工工艺优化及贮藏条件的选择提供理论依据。     

红枣粉添加量对面团特性及馒头品质的影响

研究红枣粉对面团特性及馒头品质的影响,确定适宜的红枣粉小麦粉配比。探讨了添加不同比例红枣粉（0、5%、10%、15%）对混合粉理化性质、色差、面团的微观结构和粉质拉伸特性,以及对馒头比容、色差、质构和感官品质等的影响。结果表明:随着红枣粉添加量的增加,混合粉中的水分、蛋白质和脂肪含量逐渐降低,灰分和还原糖的含量逐渐升高;混合粉及馒头的颜色逐渐变红变暗;面团吸水率逐渐降低,形成时间与稳定时间呈先上升后下降,弱化度呈先下降后上升的趋势;添加不同比例红枣粉面团随着醒发时间（45、90、135 min）的延长,面团拉伸能量、最大拉伸阻力和拉伸比等指标总体呈上升趋势;面团微观结构显示随红枣粉添加量的增加,面筋蛋白结构逐渐遭到破坏;红枣粉添加量在5%~10%范围内,馒头比容与对照组馒头相比显著增大（P<0.05）;馒头的弹性、回复性随红枣粉的添加逐渐降低;感官评定显示红枣粉添加量在5%~10%范围内,总体得分均比对照组馒头要高,且易被人们接受。综合分析红枣粉对面团特性、馒头质构及感官评价等的影响结果,确定红枣粉添加量不宜超过10%。     

不同干燥方式对枣粉品质的影响

通过对变温压差膨化干燥、真空干燥、热风干燥和真空冷冻干燥4 种干燥方式所得枣粉的物理特性和营养成分的分析测定,研究不同干燥方式对枣粉品质的影响。结果表明：在物理特性方面：真空干燥和真空冷冻干燥枣粉呈现较好色泽,真空冷冻干燥枣粉溶解性差于其他3 种枣粉,吸湿性无明显差异,变温压差膨化干燥和热风干燥枣粉复水性较好,真空冷冻干燥枣粉的粒径和堆积密度最小;在营养成分方面：4 种枣粉的营养成分较鲜样均有不同程度的降低,变温压差膨化干燥和真空冷冻干燥枣粉的还原糖和总糖含量相对较高,真空干燥枣粉总酸含量最高,真空干燥和真空冷冻干燥枣粉的VC和黄酮含量较高,真空冷冻干燥和变温压差膨化干燥枣粉的环磷酸腺苷含量稍高于其他两种。枣粉的综合评分结果显示,真空冷冻干燥枣粉品质最佳,其次是真空干燥枣粉和变温压差膨化干燥枣粉,热风干燥枣粉品质最差。真空冷冻干燥和真空干燥生产成本高,变温压差膨化干燥枣粉品质较好,且所需干燥时间短,生产效率高、成本低,适宜在枣粉加工产业推广。     

Multi-objective Optimization of Spray Drying of Jujube (Zizyphus jujuba Miller) Powder Using Response Surface Methodology

Optimum technology of spray-dried jujube powder was studied using a Box-Benhnken design. Effects of weight ratio of maltodextrin and the dry matter weight of jujube pulp (WR, 3–5), inlet air temperature (T, 140–160 °C), and shift of feed flow rate (FFR, 3–5) on the quality attributes (moisture content, lightness, the total color difference, vitamin C (VC) content and hygroscopicity) of jujube powder were systematically studied by response surface methodology and perturbation plot. Analysis of variance showed that a second-order polynomial equation could predict the experimental data well (R ²?>?0.92). Moisture content and the total color difference (?E) were significantly affected by WR, T, and FFR. The higher WR and lower FFR resulted in a decrease in moisture content and ?E. WR and FFR had extremely significant effects on VC content and hygroscopicity (P?<?0.01); with lower WR and FFR, higher values of VC content and hygroscopicity would be received. The effect of WR was the most significant variable among others. The optimum conditions that maximizing VC content and minimizing contents of moisture, ?E, and hygroscopicity of jujube powder were found as WR of 3, inlet air temperature of 140 °C, and FFR of 3 ( i.e., 11 ml/min). Under these conditions, the response values were moisture content of 3.36 %, lightness of 83.32, ?E of 9.92, VC content of 205.10 mg/100 g, and hygroscopicity of 18.59 %, respectively.     

Water Adsorption Isotherms and Storage Stability of Freeze-Dried Bovine Colostrum Powder

Moisture adsorption isotherms of freeze‐dried bovine colostrum powder were obtained using the gravimetric method at three temperatures (15, 25, and 35°C) in the water activity range of 0.11–0.86. The moisture adsorption isotherms of freeze‐dried bovine colostrum powder showed a sigmoid isotherm curve typical of the type II BET classification shape. The Guggenheim-Anderson-de Boer and Brunauer-Emmett-Teller models were recommended to fit experimental data well. The shelf life of freeze‐dried bovine colostrum powder packaged in aluminium-laminated polyethylene pouches was evaluated for 243 days, and the storage stability was investigated when stored at 25°C and 50% relative humidity. A slight increase in moisture content, a linear increase in color difference, and a slight decrease in IgG concentration were found within 60 days storage under the above-mentioned conditions.     

Processing Conditions Affecting the Hygroscopic Behavior of Freeze-Dried Passion Fruit Juice

The effect of freezing rate, freeze drying temperature, added sucrose and anticaking agents, on the water sorption kinetics and hygroscopic equilibrium of freeze-dried passion fruit juice was investigated. Slow frozen samples (-45°C) were prepared in a Harris freezer and fast frozen ones were prepared in liquid nitrogen (- 195.8°C) and a dropping technique. A freeze-drier 12F Pilot Stokes was used to freeze-dry the samples, and the studies of hygroscopicity were conducted in an automatically controlled temperature and relative humidity chamber. The results show the significant influence of the rate of freezing and added sucrose on reducing product hygroscopicity.     

Glass Transition and State Diagram for Jujube Powders With and Without Maltodextrin Addition

Both water activity and glass transition concepts were used for stability evaluation of jujube powder in this study. The water sorption behaviour at 25, 35 and 45 °C and the relationship between water content (X _w), glass transition temperature (T _g) and water activity (a _w) were investigated for jujube powder with and without the maltodextrin addition. Moisture sorption isotherms of different jujube powders were of type III and BET model was the best for fitting the experimental data. The equilibrium moisture content of jujube powder containing 20% maltodextrin at a given a _w was lower than that of pure jujube powder. However, temperature had no significant effect on the moisture sorption of jujube powders. Values of T _g of different jujube powders were obtained using differential scanning calorimetry and the glass transition line was fitted to the Gordon-Taylor model. A depression in T _g with increasing water content was observed. State diagrams of different jujube powders were established based on the moisture sorption isotherm and the glass transition curve. Results showed that jujube powders with and without maltodextrin addition were stable at 25 °C when the water content was lower than 0.0673 and 0.0566 g/g solid, respectively.     

Optimization of Short- and Medium-Wave Infrared Drying and Quality Evaluation of Jujube Powder

In this study, response surface methodology was used to optimize parameters of short- and medium-wave infrared drying processing for producing jujube powder. Optimization factors were power input (675–1,575 W), drying temperature (70–90 °C) and drying time (2.5–3.5 h), and responses were moisture content, L value, b value and vitamin C content of the jujube powder. Box–Benhnken center design was applied to the optimized the processing conditions. The optimal conditions for the production of jujube powder by the short- and medium-wave infrared drying method were power input of 1,125 W, drying temperature at 85.4 °C and drying time for 3.5 h. Under the optimal conditions, the values of moisture content, L, b and vitamin C content of jujube powder were 4.59 %, 64.46, 19.87 and 441.56 mg/100 g, respectively. Quality evaluation of the jujube powder was also investigated. The results were: hygroscopicity of 28.83 %, rehydration of 236.44 %, solubility of 53.59 %, bulk density of 0.70 g/ml, particle size of 154.2 μm, soluble solids content of 82.29 %, total sugar content of 46.87 %, reducing sugar content of 32.09 %, total acid content of 2.03 %, total flavonoids content of 1.45 % and cyclic adenosine monophosphate content of 75.32 mg/kg. The microstructure of jujube powder was irregular and 38 kinds of aroma components were generated.     

Enhanced water absorption of wheat gluten by hydrothermal treatment followed by microbial transglutaminase reaction

BACKGROUND: The water absorption of wheat gluten plays an important role in the weight, volume and form ratio of the breads. In this paper, hydrothermal treatment and microbial transglutaminase (MTGase) modification were combined to improve the water absorption ratio (WAR) of wheat gluten. To understand the increases in WAR, the changes in MTGase reaction after gluten hydrothermal treatment were also investigated. RESULTS: The sole hydrothermal treatment improved the WAR of gluten. The gluten treated at 100 °C for 30 min exhibited the highest WAR value (2.03 g g^?1 gluten) while the WAR of the control without hydrothermal treatment was 1.5 g g^?1 gluten. When gluten was exposed to 90 °C for 30 min followed by incubation with MTGase for 5 h, its WAR reached 2.48 g g^?1 gluten. In contrast to control gluten, the surface hydrophobicity of the gluten preheated at 90 °C for 30 min increased and fluctuated in a different way during the following MTGase reaction. Meantime, the trend in the amount of soluble protein of preheated gluten was also changed in the progress of MTGase reaction. CONCLUSION: Hydrothermal treatment followed by MTGase reaction is an efficient approach to improve the WAR of wheat gluten. The analysis of catalytic process, including determination of ammonia, gluten surface hydrophobicity, soluble protein and SDS–PAGE, suggested that hydrothermal pretreatment accelerated the cross‐linking reaction and may alter the ratio of gluten deamidation catalysed by MTGase, which induced an increase in the WAR. Copyright © 2010 Society of Chemical Industry     

Effects of Drying Conditions on Water Sorption and Phase Transitions of Freeze-Dried Horseradish Roots

The water sorption isotherms for freeze-dried horseradish roots (Armoracia rusticana) were determined using the interval sorption technique, and the thermal behavior of dried and rehumidified products was analyzed using differential scanning calorimetry. The hygroscopicity of the dried material increased when the surface temperature during freeze-drying was increased from 20°C to 60°C. Both sorption and thermal data showed that drying at high surface temperatures affected the physical structure of the material, resulting in increased water adsorption, decreased glass transition temperature, and increased unfreezeable water content. Water sorption isotherms and thermal data can be used to determine the proper drying and storage conditions for horseradish roots.