FUZHOU UNIVERSITY FOOD CHEMISTRY 水和溶质的相互作用 ·水结合、水合：水与亲水物质缔合的一般倾向，亲水物质 包括细胞物质。水结合或水合的程度和强度取决于包括非 水组分的本质、盐组成、pH和温度等很多因素。 ·持水力：用来描述由分子（通常由低浓度的大分子)所构 成的基质物理截留大量水以防止渗出的能力。以此方式截 留水而被大家所熟悉的食品包括果胶和淀粉凝胶以及动物 和植物组织细胞。 福
水和溶质的相互作用 • 水结合、水合：水与亲水物质缔合的一般倾向，亲水物质 包括细胞物质。水结合或水合的程度和强度取决于包括非 水组分的本质、盐组成、 pH 和温度等很多因素。 • 持水力：用来描述由分子 ( 通常由低浓度的大分子 ) 所构 成的基质物理截留大量水以防止渗出的能力。以此方式截 留水而被大家所熟悉的食品包括果胶和淀粉凝胶以及动物 和植物组织细胞
FUZHOU UNIVERSITY FOOD CHEMISTRY Water-solute interactions ·Macroscopic level Water binding(水结合)/Hydration(水合) -convey a general tendency for water to associate with hydrophilic substances,including cellular materials. Water holding capacity(持水力) -a term that is frequently employed to describe the ability of a matrix of molecules,usually macromolecules present at low concentrations,to physically entrap large amounts of water in a manner that inhibits exudation. eg.Pectin,Starch gel,Tissue -Physically Entrapped Water
Water-solute interactions • Macroscopic level Water binding（水结合）/ Hydration（水合） —convey a general tendency for water to associate with hydrophilic substances, including cellular materials. Water holding capacity（持水力） —a term that is frequently employed to describe the ability of a matrix of molecules, usually macromolecules present at low concentrations, to physically entrap large amounts of water in a manner that inhibits exudation. eg. Pectin, Starch gel, Tissue — Physically Entrapped Water
FUZHOU UNIVERSITY FOOD CHEMISTRY Physically Entrapped Water CH2OH hydration H,O O OHH,O H20 OH H,O OH OHH,O bulk water e.g.tissues, gels Other water trapped in pores -Water in pores of 10 nm less available-capillaries Physically entrapped
Physically Entrapped Water • Other water trapped in pores – Water in pores of < 10 nm less available—capillaries – Physically entrapped e.g. tissues, gels O OHH2O OH OH OH CH2OH H2O H2O H2O H2O H2O bulk water hydration
FUZHOU UNIVERSITY FOOD CHEMISTRY 水和溶质的相互作用 水溶质相互作用的分类 类型 实例 与水一水氢键①相比的相互作用温 度 偶极一离子 水一游离离子 较大② 水一有机分子上的带电基团 偶极一偶极 水一蛋白质 近乎相等 水-蛋白质c0 水一侧链0衄 疏水水合 水+R③+R(水合的) 较小（△G>0) 疏水相互作用 R(水合的)+R(水合的)· 不可比④(>疏水相互作用△G< 0) R2(水合的)坦20 注：①约12-25k灯/mo1; ②比单个共价键的强度弱得多； ③R是烷基； ④疏水相互作用是熵驱动的，而偶极一离子和偶极一偶极相互作用是焓驱动的
水和溶质的相互作用 水-溶质相互作用的分类
FUZHOU UNIVERSITY FOOD CHEMISTRY TABLE 3 Classifications of Types of Water-Solute Interactions Strength of interaction compared Type Example to water-water hydrogen bond Dipole-ion Water-free ion Greaterb Water-charged group on organic molecule Dipole-dipole Water-protein NH Approx.equal Water-protein CO Water-sidechain OH Hydrophobic hydration Water-+Rs→R(hydrated) Much less AG-0) Hydrophobic interaction R(hydrated)+R(hydrated)Ra Not comparabled(hydrophobic (hydrated)+H2O interactionAG-0) About 12-25 kJ/mol But much weaker than streng th of single covalent bond. R is alkyl group. dHydrophobic interactions are entopy driven,whereas dipole-ion and dipole-dipole interactions are enthapy driven