复合酸催化合成乙二醇单硬脂酸酯

以浓硫酸、对氨基苯磺酸作复合催化剂,采用正交实验对乙二醇单硬脂酸酯的合成条件进行了研究,并与ｓｐａｎ－６０等表面活性剂复配,制备消泡剂。     

Methane absorption and application of mixed organic aggregate prepared from Span80 and alkaline salt

The water-based materials for mine gas absorption and explosion suppression were prepared, in which the mixed organic aggregate of Span80 and alkaline salt can be used as methane absorbent. Methane was used as a model of mine gas, and the absorptions of methane with different complex materials were studied using head space gas chromatography. Then the state of aqueous material was characterized with laser light scattering instrument and the effects of different complex materials on explosion suppression were preliminarily studied in explosion chamber which can simulate mine gas explosion. The research results showed that complex material could absorb methane and there was some correlation between the mean diameter of organic aggregate in aqueous material and the absorption effect. Additionally, the aqueous material could suppress the methane explosion to some degree. The material can absorb mine gas in atomization condition, therefore, degrease mine gas concentration and influence the distribution of mine gas in the space, and then suppress the mine gas explosion to some extent.     

用单月桂酸聚乙二醇山梨醇酐酯制备溶胶凝胶毛细管气相色谱柱及其分离能力之研究

采用溶胶-凝胶法制备了以单月桂酸聚乙二醇山梨醇酐酯为固定相的毛细管气相色谱柱.该毛细管气相色谱柱显示了良好的分离能力,色谱图表明：烷烃、芳烃、醇、胺、酸、酚、酯等各种极性与非极性化合物都可在该柱上得到很好的分离.良好的重现性与平稳的基线说明色谱柱出色的热稳定性.尖锐狭窄的峰形与2 802/m的理论塔板数表明较高的柱效.对称的色谱峰与数值为1的不对称因子则表明良好的柱惰性.     

Emulsifiers affect the texture of pastes made from fermented and non-fermented cassava flours†

The effects of glycerol monostearate (GMS) and sodium steroyl lactylate (SSL) on the rheological properties of native, naturally fermented (NF) and mixed culture fermented (MCF) cassava flour pastes were measured using instrumental texture profile analysis (TPA) and by finger cohesiveness (difficulty in separation). Fermentation reduced the TPA parameters, hardness, cohesiveness and gumminess, but not springiness/elasticity. These were reduced further when either GMS or SSL were incorporated into the pastes. Pastes made from native and naturally fermented flours were scored by a Cameroonian sensory panel as difficult to separate, whereas scores for native and fermented flour pastes treated with 1% or more of GMS or SSL were easy to separate. Increased internal stability of the cassava flour starch granules was suggested as the cause of the effects.     

Enzymatic synthesis of monosaccharide fatty acid esters and their comparison with conventional products

5-O-Acyl-1,2-O-isopropylidene-D-xylofuranose and 6-O-acyl1,2∶3,4-di-O-isopropylidene-D-galactopyranose were enzymatically prepared from the corresponding monosaccharide acetals and commercial (crude) fatty acid mixtures. Subsequent acid-catalyzed hydrolysis of the isopropylidene group(s) gave monosaccharide esters with overall yields of 59–88%, where the monoester content was at least 80% (galactose oleate) and typically 90% for the other preparations. In contrast to sugar fatty acid esters prepared by conventional, high-temperature (trans)esterification, the enzymatically obtained monosaccharide esters contained no appreciable quantities of undersirable side products, and the only contaminants were monosaccharides and fatty acids.     

复配消泡剂的制备

介绍了以乙二醇单硬脂酸酯、液体石蜡为主要成分,并配以多种乳化剂和助剂在水相中复合乳化剂制备消泡剂的方法,考察了乙二醇单硬酸酯含量、液体石蜡用量、乳化剂用量,乳化剂复合、配制温度及增稠剂加料顺序对产品性能的影响,确定了复合的最佳工艺条件,该消泡剂与同类产品相比,具有工艺简单,消泡力高等特点,是一种经济实用的消泡剂。     

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