食品胶对荔枝果酱焙烤特性的影响
Effects of hydrocolloids on the bakingproperties of the litchi jam
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摘要: 采用海藻酸钠和低甲氧基(LM)果胶为添加剂,探讨体系中海藻酸钠和LM果胶的比例、p H、钙离子浓度对荔枝果酱焙烤特性的影响,并采用流变仪和气相色谱质谱联用仪对焙烤前后果酱流变学性质及香气成分进行分析。当海藻酸钠和LM果胶比例(6/4),体系的p H(3.63.8),钙离子浓度(30 mg钙/g胶)时,荔枝果酱的相对焙烤稳定性和相对形成稳定性均高于90%,且脱水收缩值低于1%。焙烤前后果酱均为屈服-假塑性流体,其流动曲线和Herschel-Bulkley模型具有较好的相关性。焙烤后荔枝果酱G’>G″,混合体系形成典型的粘弹性凝胶,以弹性为主,具有一定弱凝胶的特性。与焙烤前相比,焙烤后果酱香气成分中烯类和醇类有大幅的增加,分别增加了12%和9%,而醛和烷类物质的含量明显的减少。因此采用海藻酸钠和LM果胶可以显著提升荔枝果酱的焙烤特性。Abstract: In this paper,thealginate and low methoxyl( LM) pectin were used as additives,the effects of the ratio between alginate and LMpectin,p H and calcium concentration on the baking properties of the litchi jam were discussed.The rheological properties and aroma compounds of the pre and post- baking jam were studied by the rheometer and gas chromatography- mass spectrometer.The results indicated that with the ratio between alginate and LMpectin( 6 /4),a narrower p H range( 3.6~3.8) and a broader calcium tolerance( 30 mg Ca / g hydrocolloids)the post- baking jam illustrated the high RBS and RFS( ≥90%) and the low syneresis( ≤1%). The results also showed that pre and post- baking jam were both yield- pseudoplastic fluid andtheir flow curve which had a good correlation with the Herschel- Bulkley model.In the frequencyregion,the G' was higher than G″ of the post- baking jam leading to the mixed systemdominated by elastic,showing the typical“weak gel”properties.After baking,the contents of alkene and alcohols were greatly increased by 12% and 9% respectively,while the content of aldehydes and alkane were decreased.As a result,the baking properties of the litchi jam were enhanced by adding the alginate and LMpectin.