基于山梨醇酐单棕榈酸酯防雾膜制备与性能研究

为研究山梨醇酐单棕榈酸酯的防雾效果,以山梨醇酐单棕榈酸酯为主要防雾材料,通过造粒得到防雾母料,三层吹塑共挤得到防雾聚烯烃薄膜,并对防雾母料造粒加工性能、薄膜防雾性能、光学性能、力学性能进行测试。结果表明,随着防雾剂在母料中含量的增加,母料熔点降低,融熔指数提高,流动性得到提升,利于母料的加工;当防雾剂在薄膜中含量为时,水滴在薄膜表面接触角为9.72°,薄膜的防雾等级在水浴热雾与急速热雾法测试条件下可到达1级;防雾剂含量在薄膜中含量为1.5%高温测试环境下的持久性达到168 h;随着防雾剂含量继续增加,薄膜的力学性能与光学性能均不同程度的下降,防雾剂在薄膜中的含量在达到防雾要求时应控制在适当水平。     

浇注型水发泡室温硫化硅橡胶的制备和研究

以乙烯基硅油、含氢硅油、单硬脂酸甘油酯(简称单甘酯)和去离子水为主要原料,在铂催化剂的作用下通过加成反应制成室温硫化(RTV)泡沫硅橡胶。分析了单甘酯作为乳化剂和泡沫稳定剂对硅橡胶泡沫的发泡延时、发泡系数、孔隙率和压缩强度等性能的影响。结果表明,单甘酯用量在1～1.5份之间时发泡会更快发生;单甘酯用量为0.8份时,会明显增大发泡系数和孔隙率,制品的泡孔更加密集,均匀度更好,形状更规整。此时压缩强度达到最小,为61.75 kPa。     

失水山梨醇脂肪酸酯对聚丙烯透光率的影响

采用外涂布工艺技术制备了聚丙烯涂覆膜,并将不同浓度的失水山梨醇脂肪酸酯溶液涂覆于聚丙烯薄膜上,测试进行水浴实验之后的涂覆膜的透光率及力学性能,并与未涂膜的透光率进行对比和评价。结果表明:空白聚丙烯膜的透光率为93.24%,涂覆膜的透光率明显提高,当失水山梨醇脂肪酸酯的质量分数为12%时,薄膜的透光率最高,达96.03%;同时,涂层使薄膜的力学性能有不同程度的提高。红外光谱分析结果表明:酯基团在水浴实验时水解可生成亲水基团,改善薄膜的润湿张力,因此薄膜表面涂覆层对透光率的改善起到了较大作用。     

Influence of additives on the rheological characteristics and baking quality of wheat flours

 The response of Indian commercially milled flour to different additives was studied. The incorporation of reducing agents, such as l-cysteine hydrochloride (l-cysteine HCl), reduced the water absorption capacity (WAC) and stability of medium-strong wheat flour as well as weak wheat flour. This effect was also shown by other reducing agents or enzymes; however, the extent of change was found to be greater in medium-strong wheat flour. Surfactants/emulsifiers, such as glycerol monostearate, sodium stearoyl lactylate, and diacetyl tartaric esters of monoglycerides (DATEM), did not alter the WAC significantly, but marginally improved the stability of the dough. The change observed in the extensograph was greater with reducing agents and enzymes. In general, use of l-cysteine HCl or α-amylase or protease reduced the resistance to extension and increased the extensibility, depending on the level of addition. l-cysteine HCl, however, gave a greater reduction in the resistance to extension in medium-strong than in weak flour. On the other hand, use of surfactants/emulsifiers increased the resistance to extension and decreased the extensibility, and the effect was greater with DATEM. The bread volume improved considerably on incorporation of l-cysteine HCl, while DATEM also increased the loaf volume considerably at a 1% level in weak flour. Maximum improvement in loaf volume was found for DATEM in the case of weak flour, indicating that the responses of flour to different additives were different. Received: 10 February 1999 / Revised version: 27 April 1999     

Effect of sorbitan monostearate on the physical characteristics and whipping properties of whipped cream

In this work, the effects of sorbitan monostearate (Span 60) level on the particle size distribution, microstructure and apparent viscosity of the emulsion were investigated. Average particle size (d_4,3), surface protein concentration, partial coalescence of fat and overrun of whipped cream during whipping were also determined. As Span 60 level increased (0–0.8%) in emulsion, the apparent viscosity was increased gradually, and the particle size range was narrowed, which was also detected by microstructure. A positive effect of whipping time was observed on the average particle size, partial coalescence of fat, surface protein concentration and overrun during whipping, respectively. An increase of Span 60 level resulted in a reduction of d_4,3 values and partial coalescence of fat during 0–1 min whipping, then increasing after whipping for 2–5 min (0.6% Span 60 as the critical level). A negative behaviour was observed between surface protein concentration and Span 60. Moreover, Span 60 could improve the overrun and organoleptic properties of whipped cream efficiently.     

乳化剂在馒头中应用效果的研究

将硬脂酰乳酸钠、硬脂酰乳酸钙钠、硬脂酸聚甘油酯、单甘酯分别檬酸单甘酯加入到小麦面粉中,研究乳化剂对馒头的影响。实验结果表明:硬脂酸聚甘油酯对增强小麦粉所含面筋强度,改善面团物理性能、馒头的表面色泽,增大馒头的体积、内部组织的疏松度最为明显。其次是硬脂酰乳酸钠、硬脂酰乳酸钙钠,单甘酯和柠檬酸单甘酯改善效果最不明显。硬脂酸聚甘油酯对应的最佳添加量为小麦粉的0.4%(质量分数),对应的粒径水平为60目(250μm)。     

单甘酯在植脂末中的应用

通过研究不同单甘酯分别和硬脂酰乳酸钠复配后在乳液中的稳定性,分别得出含不饱和单甘酯、分子蒸馏单甘酯和单双甘油酯的复配乳化剂配方.研究发现用上述乳化剂配方制作的植脂末加到咖啡中可以得到不同口感.     

聚甘油单硬脂酸酯乳化二甲基硅油及乳液表征

用聚甘油单硬脂酸酯复配乳化1 Pa.s的二甲基硅油,考察复配乳化剂的亲水亲油平衡值(HLB)对乳液体积平均粒径、乳液黏度、乳液离心稳定性的影响以及乳液的耐高温稳定性。结果表明:复配乳化剂HLB值对乳液体积平均粒径、黏度、离心稳定性的影响显著,选择高聚合度的亲水型乳化剂和高聚合度的亲油型乳化剂进行复配乳化,有利于形成稳定的硅油乳液。最佳乳化条件为乳化剂(二聚甘油单硬酯和八聚甘油单硬脂酸酯,HLB=10.5)、硅油和水的质量比为7∶23∶70。在最佳乳化条件下制得的乳液体积平均粒径为8.06μm,黏度为387 mPa.s,固相质量分数差为2.91%。乳液高温稳定性良好,在110℃保持5 h,乳液体积平均粒径增大至11.63μm,固相质量分数差增大至6.12%。