响应面优化微波法提取山菠菜多糖的工艺及不同采摘期多糖含量的测定

为优化微波法提取山菠菜多糖的工艺参数,在单因素实验基础上,选择粒度、液料比、微波时间、pH进行四因素三水平的中心组合设计实验,利用Design-Expert软件进行响应面分析,得出微波法提取山菠菜多糖的最佳工艺条件为:粒度100目、液料比28∶1(mL/g)、微波时间4.5min、pH为4.6,多糖提取率实测值为3.25%,预测值为3.27%,实测值与预测值相差甚小,相对误差为1.23%,可确定利用响应面优化微波法提取多糖的工艺参数可靠,有一定的应用价值。在最佳提取工艺条件下,对不同采摘期的山菠菜多糖进行了提取测定,结果表明,不同采摘期多糖提取率差异较小。     

固相萃取-高效液相色谱法检测油炸薯条中丙烯酰胺

目的 建立了一种采用固相萃取-高效液相色谱(SPE-HPLC)测定油炸薯条中丙烯酰胺的方法.方法 样品用2.0 mol/L氯化钠溶液进行提取,使用Styre Screen H2P固相萃取柱(200 mg/3 ml)净化,然后用Sapphire C18反相色谱柱进行分析,流动相为甲醇/水(5∶95),流速为1.0 ml/min,检测波长为200 nm.结果 在1.0 ～ 10.0 μg/g的添加水平范围内,样品中丙烯酰胺的平均回收率为66.2％ ～80.9％,相对标准偏差为1.6％ ～2.1％,最低检测限和最低定量限分别为0.025和0.080 μg/g.结论 该方法操作简单、快速、准确,可用于油炸薯条中丙烯酰胺的快速测定.     

Key odorants of french fries

Twenty-one compounds, which had been screened in preceding experiments as potent odorants of french fries prepared in palm oil (PO), were quantified by stable isotope dilution assays. Nineteen odorants were dissolved in sun-flower oil in concentrations equal to those in PO. The flavor profile of the model obtained was close to that of a real sample of PO. A comparison of the complete model with models lacking one or more compounds indicated the following key odorants of PO: 2-ethyl-3,5-dimethylpyrazine, 3-ethyl-2,5-dimethylpyrazine, 2,3-diethyl-5-methylpyrazine, 3-isobutyl-2-methoxypyrazine, (E,Z)- and (E,E)-2,4-decadienal, trans-4,5-epoxy-(E)-2-decenal, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, methylpropanal, 2- and 3-methylbutanal, and methanethiol. Replacement of palm oil by coconut fat led to a coconut note in the profile of french fries. γ-Octalactone was identified as a major contributor to this note.     

Analysis of acrylamide and mechanisms of its formation in deep‐fried products

A reliable and sensitive gas chromatography‐mass spectrometry method was developed for the determination of acrylamide, a toxic compound recently discovered in baked, fried or grilled food. Satisfactory results for repeatability and recoveries were obtained by this method. The limit of detection for acrylamide was 15 μg/kg food and recoveries were between 95 to 103%. The improved method was then employed to study the influence of heat, heating time and type of frying oil on the formation of acrylamide during the deep frying of French fries. In this matrix acrylamide formation was promoted by heating in a time‐dependent manner. It appeared that acrylamide arose, when reducing sugars, dimethylpolysiloxane or partial glycerides were present. Three mechanisms of formation are discussed in this context. Although the mechanistic complexity increases dramatically in the presence of various food components, some recommendations can be given to minimize acrylamide levels in deep fried products.     

橄榄油与橄榄油基二酯油煎炸薯条品质差异分析

甘油二酯(DAG)作为一种低热值的功能性脂质，因其特殊的理化性质和生理功能被广泛应用于食品体系中。为了考察DAG油作为煎炸油的可行性，以橄榄油基二酯油(ODO,82.3%)和橄榄油(OO,92.43%)煎炸薯条，对比研究两种油煎炸后的薯条在水分含量、质构、油含量、色泽、淀粉糊化度以及体外模拟消化淀粉水解率等方面的差异，并用扫描电子显微镜观察消化过程中薯条表面的微观形态变化，最后对两种油煎炸的薯条进行感官评价。结果表明：ODO煎炸薯条的水分含量(57.07%)、油含量(28.15%)、淀粉糊化度(90.7%)、体外模拟消化淀粉水解率(63.02%)分别高于OO煎炸薯条的水分含量(49.93%)、油含量(25.74%)、淀粉糊化度(88.3%)和体外模拟消化淀粉水解率(53.47%);在质构和色泽上，与OO煎炸薯条相比，ODO煎炸薯条具有更高的脆度、更低的硬度及更好的色泽；从微观形态看，ODO煎炸薯条外表面淀粉颗粒的收缩、分散和变形更明显，经体外模拟消化后，OO和ODO煎炸薯条均发生了较大的细胞破裂，其中ODO煎炸薯条显微结构破坏更严重；OO和ODO煎炸薯条在口感、外观、风味、油腻性、脆度...