【作者】 李慧芸；

【导师】 张宝善；

【作者基本信息】 陕西师范大学 ， 食品科学， 2005， 硕士

【摘要】 红枣（Zizyphu jujuba Mill）系中国的特色果品。我国枣树栽培面积已达33万多ha,年产鲜枣11亿kg,占世界鲜枣总产量的95%以上。红枣富含多种营养物质,特别是含有多糖、黄酮等活性成份,因此,红枣具有很高营养价值及多种保健功能。 本试验以陕西省佳县油枣为原料,研究内容是:油枣在干制过程中总糖、还原糖、氨基酸、抗坏血酸、5-HMF及A₄₂₀值的变化;枣浆在加热过程中,加热温度、加热时间、pH值、添加剂等对非酶褐变的影响;有机酸、亚硫酸盐和谷胱甘肽、半胱氨酸、胱氨酸对枣浆非酶褐变的抑制作用等。试验结果如下: 1.油枣中的总糖、还原糖、氨基酸和抗坏血酸等物质,在干制过程中极易发生非酶褐变。 2.枣浆在加热过程中,5-HMF的变化符合零级动力学模式,褐色素的生成符合一级动力学模式,两反应的活化能分别是28.9469kJ/mol和31.5092kJ/mol。 3.枣浆在加热过程中,体系的自然pH值呈下降的趋势。pH值为2时,目测枣浆立刻呈现褐色;pH值为3时,褐变程度最轻;pH值为4～6时,褐变程度随pH值的升高而加剧。 4.浓度各为1%和2%的赖氨酸和甘氨酸均可促进枣浆非酶褐变。1%天冬氨酸可抑制枣浆非酶褐变。 5.还原糖促进枣浆非酶褐变,果糖比葡萄糖的促进作用大。加热5h,加入果糖的枣浆A₄₂₀值比加入葡萄糖的高0.206。 6.Cu²⁺、Fe³⁺和Fe²⁺可显著促进枣浆非酶褐变;Mn²⁺和Zn²⁺促进作用不显著;Al³⁺、Sn²⁺和Ca²⁺可抑制枣浆非酶褐变。 7.抗坏血酸、柠檬酸和EDTA均可抑制枣浆非酶褐变,三者最佳抑制浓度分别为0.04%、0.5%和0.04%。 8.谷胱甘肽、半胱氨酸浓度各为0.10%时,均可显著抑制枣浆非酶褐变。当浓度各为0.15%时,产品具有刺激性气味。 9.NaHSO₃对枣浆非酶褐变的抑制率与其浓度呈正相关;Na₂SO₃0.03%时抑制效果显著,浓度提高为0.04%时,抑制效果增加不明显。更多还原

【Abstract】 The Chinese jujube (Zizypus jujuba Mill), a special fruit growing in China. The plantation area of Chinese jujube has increased 0.33 million ha, with an annual output of 1.1 billion kg, accounting for 95% of the total world output. As we know, Jujube Mill has a high nutritional value, especially Jujube date contains polysacchride, cyclic, which make Jujube date has all kinds of biological function.The changes of sucrose, reducing sugar, amino acid, ascorbic acid, 5-HMF and A420 in Jujube during heating; the effect of heating temperature, heating time, pH and additive on nonenzymatic browning of Jujube pulp; the inhibiting effect of organic acid, sulphite, glutathione, cysteine and cystine on nonenzymatic brown of Jujube pulp are studied in this paper. The results showed that:1. The sucrose, reducing sugar, amino acid and ascorbic acid in Chinese jujube are easily to brown.2. During heating of Jujube pulp, the changes of 5-HMF follows zero order kinetics while the changes of brown pigment follows first order kinetics. Activation energy values of 28.9469 and 31.5092 kJ/mol are obstained for 5-HMF and brown pigment, respectively.3. During heating of Jujube pulp, pH value decreases. When pH value is 2, Jujube pulp is brownish at once; when it’s 3, browning is slightly; when it’s 4-6, higher the pH value is, greater the brown becomes.4. 1% and 2% lysine and glycin can accelerate nonenzymatic brown of Jujube pulp. 1% asparagine can inhibit nonenzymatic brown of Jujube pulp.5. Reducing sugar can accelerate nonenzymatic brown of Jujube pulp, the effect of fructose is higher than glucose.6. Cu~2+, Fe~3+ and Fe~2+ can accelerate nonenzymatic brown of Jujube pulp evidently; Mn~2+ and Zn~2+ have slight effect on nonenzymatic brown of Jujube pulp; Al~3+, Sn~2+ and Ca~2+ can inhibit nonenzymatic brown of Jujube pulp.7. Ascorbic acid, citric acid and EDTA can all inhibit nonenzymatic brown of更多还原