甲基及羟丙甲基纤维素在食品行业的应用.ppt

Benecel主要牌号 Benecel 产品 Backup(1) 分散体系的分类 Backup(2) 聚集态不同的分散体系 * * * * * * As mentioned in the previous slides, salt will depress the gelling temperature of MC and HPMC. In this chart some of that work is represented as an example to illustrate what can happen. MC grades (A-types) are most sensitive. Gelling temperature is depressed at 2% salt. At 5% salt is so depressed it cannot stay in solution even at ambient temperature. Substitution with propoxyl has protective effect, the F type can tolerate 5% salt. Effects of Mw are also seen here. Higher chain length will make the Benecel less tolerant to solutes, low Mw is more soluble as a rule. So it can be seen how the low viscosity K-type can tolerate the presence of 5% salt whereas the higher Mw grade is insoluble at 5% salt at room temperature. * Sugar will also impact gelling temperature, 10 and 20% sugar will present gelling temperature 5 to 10 degrees C. 40% sugar depresses the gelling temperature much more. As with the salt, the higher Mw grades and the MC A-type was not tolerant to the high sugar dose. * * * * These are the grades offered by Aqualon. For each chemistry (A, E, F and K) there are various offerings in Mw or viscosity. All viscosities are reported as 2% in water. 甲基及羟丙甲基纤维素 在食品行业中的应用 Date 16, Mar.,2011 内容概要 化学构成 什么是热凝胶 热凝胶特性如何起作用 如何控制凝胶温度和强度 热凝胶特性的应用 其他重要特性 化学结构 什么是热凝胶 其水溶液在温度升高时形成凝胶 当温度恢复后，其凝胶消失，溶液恢复原来的粘度即具有可逆性 与琼脂和明胶等胶体的凝胶特性恰恰相反（在常温下凝胶） 热凝胶特性如何起作用 随着温度上升，粘度急剧下降 过了凝胶温度，粘度急剧上升 当温度下降后，粘度变化如虚线所示，最终恢复起始粘度 随着甲氧基和羟丙氧基的含量不同： 凝胶温度不同 凝胶强度不同 冷却后粘度恢复的快慢不同 A F K 如何控制凝胶温度和强度 凝胶强度直接与甲氧基和羟丙氧基含量相关 甲氧基含量越高，凝胶温度越低，凝胶强度越大 羟丙氧基含量越高，凝胶温度越高，凝胶强度越小 Benecel Type % OCH3 % POOH Gel Temperature * Gel Type A type 27.5 - 31.5 - 50 - 55 硬 E type 28 - 30 7 - 12 58 - 64 软硬适中 F type 27 - 30 4 - 7.5 62 - 70 软硬适中 K type 19 - 24 4 - 12 70 - 90 软 *2% MC or HPMC in water 体系其他组分的影响 体系中其他组分如糖、盐和有机溶剂等会影响热凝胶温度的高低 选用凝胶温度高的产品，通过在配方