乙酰化脱氧雪腐镰刀菌烯醇污染、毒性及转化研究进展

脱氧雪腐镰刀菌烯醇（deoxynivalenol,DON）俗称呕吐毒素,是禾谷镰刀菌等真菌产生的次级代谢产物,是谷物原料及其制品中最常见的污染物之一。DON的产生往往伴随其主要乙酰化衍生物3-乙酰基-DON和15-乙酰基-DON的产生,这些衍生物表现出与DON相似甚至更强的毒性,因而增加了谷物及其制品的食用安全风险。本文简述了DON乙酰化衍生物的产生、检测技术及污染现状,重点分析了DON乙酰化衍生物的毒性及转化研究进展,以期为粮食中DON乙酰化衍生物的降解和防控研究提供理论参考。     

壳聚糖及丁二酸酐酰化壳聚糖双氧水降解行为的研究

在简单均相体系下．研究了壳聚糖及丁二酸酐酰化壳聚糖在双氧水中的降解特性。采用鸟氏粘度计,利用一点法测量了降解过程中壳聚糖及丁二酸酐酰化壳聚糖的分子量,讨论了该体系下壳聚糖及丁二酸酐酰化壳聚糖的降解速率．通过红外光谱分析了双氧水对低分子量壳聚糖和低分子量丁二酸酐酰化壳聚糖结构的影响。结果表明．在该体系下·壳聚糖及丁二酸酐酰化壳聚糖的降解主要发生在反应开始后的2～3h内．此后降解产物的分子量逐渐趋于20000;相同条件下,丁二酸酐酰化壳聚糖的降解程度高于壳聚糖;红外光谱表明．采用该降解体系制备的降解产物主链结构基本没有发生变化。     

Kaempferol acetylated glycosides from the seed cake of Camellia oleifera

The seed cake is a big by-product after crushing cooking oil from the seeds of Camellia oleifera Abel. Chemical investigation on the seed cake of C. oleifera led to the isolation of two new kaempferol acetylated glycosides (1 and 2). In addition, five kaempferol glycosides (3–7) and their aglycone, kaempferol (8), were also obtained, in addition to gallic acid (9). Their structures were determined by the detailed spectroscopic analysis and acidic hydrolysis. The new compounds were characterised as kaempferol-3-O-[4′′′′-O-acetyl-α-l-rhamnopyranosyl-(1→6)]-[β-d-glucopyranosyl-(1→2)]-β-d-glucopyranoside (1) and kaempferol-3-O-[4′′′′-O-acetyl-α-l-rhamnopyranosyl-(1→6)]-[β-d-xylopyranosyl-(1→2)]-β-d-gluco-pyranoside (2), respectively. The DPPH radical scavenging activity of all the isolated compounds was described.     

Toxicological evaluation of acetylated faba bean globulin

Acetylated faba bean globulin (acVFG, acetylation degree 97%) was evaluated toxicologically in a subchronic feeding study and a female fertility test. Groups of male and female rats received acVFG in their diet at levels of 20, 40 and 80 g kg⁻¹ for 3 months. Additional groups were fed a commercial diet or given food containing 38 or 75 g kg⁻¹ casein. The subchronic toxicity study revealed growth retardation in both sexes at the 80 g kg⁻¹ acVFG level. The food consumption was reduced in males at 40 and 80 g kg⁻¹ acVFG and in females at 80 g kg⁻¹ acVFG. Histopathological alterations in the ovaries were observed at dietary levels of 40 and 80 g kg⁻¹ acVFG. Histopathological changes and decreases in the absolute and relative weight of the uterus were found in all groups fed acVFG. Therefore a no‐observed‐effect level (NOEL) was not derivable. Feeding females 80 g kg⁻¹ acVFG resulted in diminished pre‐implantation losses but increased post‐implantation losses in the fertility study. © 2000 Society of Chemical Industry     

花生壳纳米纤维素的制备及其对淀粉膜性能的影响

以花生壳纤维素为原料,采用酸水解法制备花生壳纳米纤维素,对花生壳纳米纤维素的形貌,结晶结构及其对淀粉膜性能的影响进行研究。结果表明,花生壳纳米纤维素为棒状结构,长度为150 nm左右,直径为10~15 nm;X-射线衍射表明其仍具有纤维素的晶型,结晶度有所提高;添加花生壳纳米纤维素可以有效提高氧化酯化木薯淀粉膜的拉伸强度、水溶时间和热稳定性,降低水蒸气透过系数,添加6%花生壳纳米纤维素制备的复合膜结构紧密、光滑平整。     

Fiber-reinforced cellulosic thermoplastic composites

Steam-exploded fibers from Yellow poplar (Liriodendron tulipifera) wood were assessed in terms of their thermal stability characteristics, their impact on torque during melt processing of a thermoplastic cellulose ester (plasticized CAB) matrix, their fiber–matrix adhesion and dispersion in composites, and their mechanical properties under tension. Fibers included water-extracted steam-exploded fibers (WEF), alkali extracted fibers (AEF), acetylated fibers (AAEF), and a commercial milled oat fiber sample (COF) (i.e., untreated control). The results indicate that the thermal stability of steam-exploded fibers increases progressively as the fibers are extracted with water and alkali and following acetylation. The greatest improvement resulted from the removal of water-soluble hemicelluloses. The modification by acetylation contributed to improved interfacial wetting that was revealed by increased torque during melt processing. Whereas modulus increased by between 0 and 100% with the incorporation of 40% fibers by weight, tensile strength either declined by ⅓ to ½ or it increased by a maximum of 10%, depending on fiber type. AAEF composites produced the best mechanical properties. Fiber–aspect ratio was reduced to an average of 25–50 from ≫ 200 during compounding. The superior reinforcing characteristics of AAEF fibers were also reflected by SEM, which revealed better fiber–matrix adhesion and failure by fiber fibrillation rather than by fiber pullout. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1329–1340, 1999     

Enzymatic degradation of native and acetylated starch-based extruded blends

Blends including natural wheat starch and acetylated starch (with substitution degree 1.5) have been extruded so as to obtain a new packaging material. The influence of this extrusion upon the biodegradability of the blends was studied for several acetylated to natural starch ratios both by a colourimetric method (measure of reducing sugars) and by chromatographic analysis (determination of quantities of degradation products). The action of a single α-amylase (Fungamyl 800 from Aspergillus oryzae) only leads to degradation of the unmodified part of the starch. On the other hand, an acetylesterase (Viscozyme from Aspergillus niger) acting in synergy with the same α-amylase leads to significant degradation of the two major components of the extruded blends. For instance, with 10% acetylated starch 100% of the blend is degraded. The major product of degradation is glucose (97%) because Viscozyme also has α-glucosidase activity. So, the present study shows the degradable character of this new packaging material even with a high acetylation value. © 1998 John Wiley & Sons, Ltd.     

乙酰化辣木多糖的制备及其抗氧化活性研究

以辣木为原料,采用水提醇沉法制备辣木多糖。利用乙酸酐为乙酰化试剂,对辣木多糖进行乙酰化修饰。通过单因素实验和正交实验,确定了辣木多糖乙酰化修饰的最佳工艺条件。在此基础上,对乙酰化辣木多糖进行抗氧化性实验。结果表明,制备乙酰化辣木多糖的最优实验条件为反应时间6 h,反应温度60℃,乙酸酐用量5 m L。抗氧化活性研究结果显示,辣木多糖乙酰化改性后清除羟自由基和超氧阴离子自由基的能力显著增加。表明乙酰化修饰可显著提高辣木多糖的抗氧化性。      

油炸方便面面身复合食品添加剂的应用研究

探讨了复合食品添加剂在油炸方便面面身中的主要作用，研究了木薯变性淀粉、谷朊粉、分子蒸馏单甘酯、蔗糖酯、瓜尔豆胶、复合磷酸盐、纯碱的不同添加量对方便面面身品质的影响。实验结果表明，在100kg面粉中添加水36．5kg，食盐2．2kg，纯碱250g，复合磷酸盐300g，谷朊粉500g，蔗糖酯50g，瓜尔豆胶100g，木薯变性淀粉4kg可以做出符合实验要求的爽滑、筋斗、复水性好、耐贮藏的方便面。     

超声波强化制备高取代度大米淀粉乙酸酯

高取代度乙酸酯(DS>2)由于其热塑性及疏水性, 在高分子领域应用广泛。以大米淀粉为原料, 对甲苯磺酸为催化剂, 在冰乙酸/乙酸酐体系中, 采用了超声强化方法制备高取代度乙酸酯淀粉, 并用FTIR、XRD 和SEM对产物进行表征。考察了超声作用时间、超声温度、超声功率对大米淀粉乙酸酯取代度(DS)的影响, 并用响应面法对超声条件进行了优化, 得到的最佳工艺如下:超声时间为15.67min, 超声温度为31.33℃, 超声功率为85.60W, 在此条件下, 得到的乙酸酯淀粉的取代度为2.77。由FTIR图谱可知, 乙酸酯淀粉在1750cm^-1、1433cm^-1、1375cm^-1及1239cm^-1处出现了乙酰基的特征峰, 证明成功地制得了高取代度乙酸酯淀粉。XRD和SEM结果表明, 乙酰化后淀粉的结构完全被破坏。研究结果为高取代度淀粉乙酸酯的工业生产提供了依据。