Physical Aging of Amorphous Fructose

ABSTRACT: Physical aging of amorphous anhydrous fructose at temperature 5 °C and at 22 °C was studied using differential scanning calorimetry (DSC). The dynamic glass transition temperature, T_g0 for unaged samples was 16 °C and 13.3 °C for heating rate of 10 °C/min and 1 °C/min, respectively. The fictive temperature, T_f0 for unaged samples calculated by Richardson and Savill method was 12 °C, which is close to the dynamic value obtained from the lower DSC heating rate. The fictive temperature T_f of the aged fructose glasses at temperatures both below and above the transition region was fitted well by a non-exponential decay function (Williams-Watts form). Aging above the transition region (22 °C) for 18 d increased both the dynamic glass transition temperature T_g and the fictive temperature T_f. However, aging below the transition region (5 °C) for 1 d increased the dynamic glass transition temperature T_g but decreased the fictive temperature T_f.     

己糖生产甘露醇概述

葡萄糖、果糖和甘露糖同属己糖,均是工业生产甘露醇最直接的原料.介绍了作为生产甘露醇最直接的原料三种单糖,它们之间的关系以及是如何转化为甘露醇与转化过程的机理.     

高效液相色谱法测定低聚果糖

提出用高效液相色谱法（ Ｈ Ｐ Ｌ Ｃ）, Ｂｏｎｄａｐａｋ Ｎ Ｈ２ 柱为分析柱,乙腈—水（３∶１, Ｖ／ Ｖ）为流动相,示差折 光仪为检测器,一次进样能同时测定低聚果糖样品中的果糖、蔗糖、蔗果三糖（ Ｇ Ｆ２ ）、蔗果四糖（ Ｇ Ｆ３ ）、蔗果五糖（ Ｇ Ｆ４ ）、蔗果六糖（ Ｇ Ｆ５ ）等。本法测定了样品“博爱生命素”和“火麻仁内清液”,所得结果良好,变异系数为 ０９ ％ ～１５ ％ ,线性相关系数 ｒ 为 ０９９９０～０９９９９。     

葡萄糖-6-磷酸和果糖-6-磷酸的酶法测定

在血液、发酵液或组织液中加入磷酸葡萄糖异构酶（ＰＧＩ，ＥＣ．５．３．１．９）、６－磷酸葡萄糖脱氢酶（ＧＤＨ，ＥＣ．１．１．１．４．９）及还原型辅酶Ⅱ（β－ＮＡＤＰ），利用快速、准确的酶法检测Ｄ－６－磷酸葡萄糖和Ｄ－６－磷酸果糖浓度。对该法的专一性、精确性、准确性以及误差来源及消除方法作了讨论。对其它物质的分析作了探讨     

Glycation of soy protein isolate with two ketoses: d-Allulose and fructose

Modification of food proteins to have improved functional properties is of great importance. In this study, modification of soy protein isolate (SPI) was achieved through glycation. SPI was glycated in a spray dryer (SD) and an incubator followed by freeze drying (FD). d -Allulose, an important rare sugar, was used in SPI glycation as the carbohydrate source, and results were compared with fructose. In addition to the sugar type, two different SPI powder: sugar ratios (1:1 and 5:1) were investigated. For the glycated samples, emulsification activity, free amino groups, protein solubility, Fourier-transform infrared spectroscopy analysis, antioxidant activity experiments and time-domain NMR relaxometry measurements for hydration were conducted. According to the results, the solubility of SPI that is limited in native form has shown a significant improvement after glycation through both FD and SD methods. Besides, glycation through the FD method was found to be more favourable due to its milder conditions than the SD method. Considering the physicochemical properties, the best combination for the highest glycation degree was found to be the samples prepared at the 1:1 ratio with d -Allulose in the FD method. Overall, it was concluded that glycation of SPI enhanced its functional properties such as antioxidant and emulsification activities.     

环保型果糖/尿素树脂的合成及应用

为了降低传统脲醛树脂中甲醛的危害,采用了果糖代替甲醛与尿素合成了环保型果糖/尿素树脂,并用合成出的树脂与芦苇纤维复合制备了芦苇纤维板,考察了树脂合成过程中果糖/尿素物质的量之比、反应温度、反应时间、催化剂种类等工艺参数对树脂及芦苇纤维板性能的影响,得到了果糖/尿素树脂的最佳合成工艺,即果糖/尿素/催化剂盐酸的物质的量之比为2.5/1/0.13、反应温度为91℃、反应时间为3 h。在此最佳合成工艺下合成的树脂固含量为65.57%、黏度为73 m Pa·s,由此树脂制备的芦苇纤维板的静曲强度为26.19 MPa,弹性模量为6.13 GPa,完全满足国家标准GB/T 11718–2009的要求。     

乙酰水杨酸对番茄果实内各部位糖分含量的影响

采用不同浓度乙酰水杨酸处理番茄果实,对在不同发育阶段果实各部位组织中的糖分含量变化进行了测定,结果表明:在番茄果实不同发育期,果实果皮、胶质胎座和心室隔壁中果糖、葡萄糖和蔗糖含量均表现不同程度的增加,但对果实维管束中糖分含量影响不大,说明乙酰水杨酸具有提高番茄糖分含量的作用。     

Glucose and Fructose Fermentation by Wine Yeasts in Media Containing Structurally Complex Nitrogen Sources

Glucose and fructose fermentations by industrial yeasts strains are strongly affected by both the structural complexity of the nitrogen source and the availability of oxygen. In this study two Saccharomyces cerevisiae industrial wine strains were grown, under shaken and static conditions, in a media containing either a) 20% (w/v) glucose, or b) 10% (w/v) fructose and 10% (w/v) glucose or c) 20% (w/v) fructose, all supplemented with nitrogen sources varying from a single ammonium salt (ammonium sulfate) to free amino acids (casamino acids) and peptides (peptone). Data suggest that a complex structured nitrogen source is not submitted to the same control mechanisms as those involved in the utilization of simpler structured nitrogen sources, and mutual interaction between carbon and nitrogen sources, including the mechanisms involved in the regulation of aerobic/anaerobic metabolism, may play an important role in defining yeast fermentation performance and the differing response to the structural complexity of the nitrogen source, with a strong impact on fermentation performance.     

Sugar content of swedes for stockfeeding

The sugar content was determined of 19 cultivars of swede (Brassica napus ssp rapifera L) grown in rows 50 and 75 cm apart. Sugar concentration ranged from 54.3 to 78.7 g kg^?1 fresh weight and was positively correlated with dry matter content which ranged from 90.4 to 138.7 g kg^?1 fresh weight. The average concentration of fructose, glucose and sucrose in the dry matter was 225.0, 328.4 and 34.5 g kg^?1 DM, respectively. The high-dry-matter cultivars tended to have less fructose and more sucrose than the low-dry-matter ones, but total sugar concentration in the dry matter was not associated with dry-matter content. Row width had little effect on sugar content compared with the differences between cultivars. The implications for the feeding value of swedes are discussed.