【作者】 陈勇；

【导师】 栾广忠；

【作者基本信息】 西北农林科技大学 ， 食品工程（专业学位）， 2016， 硕士

【摘要】 大豆除了含有丰富的营养物质以外,还含有脲酶、胰蛋白酶抑制剂和脂肪氧化酶等抗营养因子,这些抗营养因子对大豆的营养效价有着很大的不良影响。目前已经有很多关于钝化大豆抗营养因子的研究,但是同时研究这三种抗营养因子的研究比较少。本研究分别采用微波处理、射频处理和烘烤处理对大豆进行加热,研究不同加热条件对脲酶、胰蛋白酶抑制剂和脂肪氧化酶等抗营养因子的钝化效果,并测定大豆的氮溶解指数、颜色和气味等品质指标。然后对大豆进行润湿,调节水分,并研究分析不同含水量对微波钝化大豆抗营养因子影响。结果如下所示:(1)经过微波(385 W)加热3 min、射频加热600 s、烘烤(150℃)加热45 min后,大豆脲酶活性和胰蛋白酶抑制剂活性从10.19U?g-1和59.87 mg?g-1分别降到0.11 U?g-1和11.65 mg?g-1、0.25 U?g-1和7.76 mg?g-1、0 U?g-1和22.53 mg?g-1,其中胰蛋白酶抑制剂抑制率分别达到了80.54%、87.03%、62.37%。而大豆脂肪氧化酶较容易钝化,在微波加热2.5 min或烘烤(130℃)30 min或烘烤(140℃)15 min或射频加热550 s后几乎完全钝化。随着加热时间和温度的增加,抗营养因子的抑制率大幅增加。(2)经过微波(385 W)加热3 min、射频加热600 s、烘烤(150℃)加热45 min后,大豆NSI值从80.05%分别降到了10.65%、9.49%、5.44%;大豆的L,a和b值从85.91,-0.93和20.71分别变为81.42,2.11和22.04、75.58,5.38和24.23、74.24,5.98和24.48;而代表大豆主要香气成分的2号和7号传感器的G/G0(相对电阻率值)从2.16和3.36分别增加到了2.84和5.27、3.29和5.37、6.38和9.45。随着加热时间和温度的增加大豆NSI值大幅降低、颜色逐渐加深、香气成分含量逐渐增加。(3)对于微波(385 W,2 min)处理,当大豆含水量由5.39%增加到9.00%时,脲酶活性和胰蛋白酶抑制剂活性分别从5.46 U·g-1和47.37 mg·g-1降到0.35 U·g-1和10.39mg·g-1;NSI值由31.79%降到9.51%;L,a和b值分别由85.74,-0.76和20.52变为84.78,0.22和19.44。当水分含量达到7%时脂肪氧化酶就已经完全失活。随着水分含量的增加,抗营养因子活性迅速降低,NSI值大幅下降,颜色也有一定程度加深;而增香效果却是先降低后增加,在含水量为7%时,香气成分达到最小值。根据以上结果可以得出结论:微波加热钝化抗营养因子效果更好、时间短、速度快,而且对大豆品质影响更小。因此微波加热是三种加热方式中最好的加热方法,而且水分含量变化对微波加热效果影响显著。更多还原

【Abstract】 Soybean contains some anti-nutritional factors, such as urease, lipoxygenase and trypsin inhibitor, in addition to containing abundant nutrient substance. These anti-nutritional factors have bad influence on soybean nutritive value. There are already a lot of researches on the passivation of soybean anti-nutritional factors, but there is a few researchers studying the three anti-nutritional factors simultaneously. In this study, soybeans were heated by microwave, radio frequency and baking and the effect of different heating conditions on soybean urease, trypsin inhibitors, lipoxygenase, nitrogen solubility index, color and smell was investigated. Then soybeans were soaked with different amount of water and the effect of different moisture content on soybean anti-nutritional factors and quality was analyzed. The results are shown below:(1) The activity of soybean urease and trypsin inhibitor decreases from 10.19 U?g-1 and59.87 mg?g-1 to 0.11 U?g-1 and 11.65 mg?g-1, 0.25 U?g-1 and 7.76 mg?g-1, 0 U?g-1 and 22.53mg?g-1 respectively after microwave(385 W)heating for 3 min, RF heating 600 s, baking(150℃) for 45 min and the inhibition rate of trypsin inhibitor is respectively 80.54%, 87.03%,62.37%. It’s easy to passivate the lipoxygenase of soybean, and the activity of lipoxygenase is almost 0 after microwave heating for 2.5 min, baking for 30 min at 130℃, baking for 15 min at 140 ℃ or RF heating for 550 s. As the heating time and temperature increasing, the inhibition rate of anti-nutritional factors increases a lot.(2) The NSI value of raw soybean decrease from 80.05% to 10.65 %, 9.49 %, 5.44 %respectively after microwave heating for 3.0 min, RF heating 600 s, baking(150℃) 45 min.The L, a and b value of soybean become from 85.91,-0.93 and 20.71 to 81.42, 2.11 and 22.04;75.58, 5.38 and 24.23; 74.24, 5.98 and 24.48 respectively after microwave heating for 3 min,RF heating 600 s, baking(150℃) 45 min. The aroma components represented by No.2 and No. 7 sensor of electronic nose are the subject of soybean aroma components. The G/G0(relative resistivity values) of No. 2 and No. 7 sensors which represent main soybean aroma components increases from 2.16 and 3.36 to 2.84 and 5.27, 3.29 and 5.37, 6.38 and 9.45 after microwave heating for 3min, RF heating for 600 s, baking(150℃) for 45 min. As the heating temperature and time increasing, the NSI value decreases a lot, but the color of soybean darker gradually and the content of aroma components increases gradually.(3) When the moisture content comes to 7%, lipoxygenase has been completely inactivated. When the moisture content increases from 5.39% to 9.00%, the urease activity and trypsin inhibitor activity of soybean heated by microwave for 2.5min decreases respectively from 5.46 U·g-1 and 47.37 mg·g-1 to 0.35 U·g-1 and 10.39 mg·g-1; the NSI valuedecreases from 31.79% to 9.51%; and the L, a and b value of soybean become from 85.74,-0.76 and 20.52 to 84.78, 0.22 and 19.44. When the moisture content is 7%, the lipoxygenase is passivated completely. As moisture content increasing, the anti-nutritional factors activities and NSI value decrease gradually; the soybean color daker gradually. While the aroma components reduce first and then increase as the moisture content increasing, and reaches the minimum when the moisture content is 7 %.According to the results, we can conclude that microwave heating is more effective and faster on passivating anti-nutritional factors and there is less effect on soybean quality by microwave heating. So microwave heating is the best one among the three heating methods and the change of moisture content has significant effect on microwave heating.更多还原