超临界CO2状态下酶法合成富含中链脂肪酸的玉米油

研究了在超临界CO2状态下,采用脂肪酶催化辛酸与玉米油反应制备富含辛酸甘油酯玉米油的工艺,分别考察了酶用量、反应压力、温度和时间对辛酸酯化率的影响。最佳的工艺条件为:酶用量5%,反应温度60℃,反应时间24h,反应压力11MPa,在此条件下辛酸的酯化率可达到90.73%。反应产物的脂肪酸组成中,具有生理活性的中链脂肪酸含量高达32.00%。     

小组合设计优化超声辅助酶法提取黑玉米粗多糖

为优化黑玉米多糖的超声辅助酶提取工艺,应用小组合试验设计,采用响应面法对提取工艺条件进行优化,确定黑玉米粗多糖超声辅助酶提取工艺的最佳条件:超声作用时间33 min,提取温度59℃,纤维素酶添加量1.23%,中性蛋白酶添加量0.93%,在此条件下多糖得率达46.01%,所建立的数学回归模型能够较准确预测黑玉米多糖的得率。     

玉米醇溶蛋白生产新工艺的研究

通过对脱色步骤和沉淀步骤的改进，找到一条玉米醇溶蛋白生产的新工艺，分别研究了脱色，提取和沉淀３个步骤中各种工艺参数生产的影响，摸索出本工艺的最佳工艺条件：脱色：乙醇回流温度下，萃取５ｈ；提取：温度６０℃，时间２ｈ，乙醇浓度７０％，液固比１０：１（ｍｌ／ｇ）；沉淀：沉淀温度０℃，沉淀剂与醇溶蛋白浓缩提取液比３０：１（ｖ／ｖ）。     

玉米原料超高浓度酒精发酵

以全磨玉米为原料,研究了超高浓度条件下传统工艺与生料工艺的黏度变化。采用传统工艺,在超高浓度条件下,物料的糊化、液化会变得非常困难。而采用生料工艺,黏度始终维持在合理的水平。对高浓度传统工艺和生料工艺发酵的结果进行对比,证明生料工艺可以产出更多的酒精;对超高底物浓度(35%绝对干物)生料发酵时采用温度梯度控制,使用市售酒精干酵母,在98 h内发酵醪液酒精浓度可达20%以上。     

成熟度对糯玉米品质和风味的影响

以不同成熟度的3种糯玉米为材料,通过可溶性固形物、还原糖、VC、蛋白质含量及其过氧化物酶(POD)和多酚氧化酶(PPO)活性等品质指标的测定,并结合固相微萃取气质联用法(SPME/GC-MS)对糯玉米挥发性物质成分及相对含量的分析,考察成熟度对糯玉米品质及风味成分的影响。结果表明：不同成熟度的糯玉米品质指标和香气成分具有显著差异,品质指标大致呈波动变化,而其含量随成熟度增加呈下降趋势。香气成分在渝甜糯中共检出46种,渝科糯中检出33种,渝糯3000中共检出47种,主要成分为烯萜类和醇类,含量超过50%,其中在第四成熟期香气物质含量最丰富。     

A-型淀粉球晶的制备及表征

通过盐酸的温和酸解作用，使玉米淀粉颗粒的无定型区域水解，得到结晶度较高的酸解淀粉。将该酸解淀粉溶解后冷冻重结晶，制备出B-型球晶，在此基础上进一步重结晶制备得到了A-型淀粉球晶。用扫描电子显微镜(SEM)、X-射线衍射、热重分析法(TG)以及凝胶渗透色谱(GPC)等方法对所得的淀粉球晶进行了表征。结果表明所得A-型球晶的平均粒径约为3μm，晶体形态为A型、其热分解起始温度低于天然淀粉而高于酸解淀粉和B型球晶，组成球晶的淀粉分子链长度约为14个葡萄糖单元。     

玉米粉配比对玉米-小麦混合粉及其馒头品质的影响

采用不同的配比将玉米粉与小麦粉搭配,通过测定玉米-小麦混合粉指标和馒头指标,以研究玉米粉对混合粉及其馒头品质的影响。结果表明:随着玉米粉比例的增加,混合粉的吸水率、稳定时间、粉质指数呈逐渐减小的趋势;最大抗延伸性、拉伸面积、沉降值、湿面筋、面筋指数也逐渐降低;峰值黏度、稀懈值、回升值、降落数值等都有所下降,而糊化温度和弱化度有所上升。玉米粉的使用在一定程度上影响了面团的流变学性能,降低了面筋的品质,但是在比例不超过15%时影响并不十分明显,辅以一定的改良技术,不但可以生产出食用品质优良的馒头,而且可以改善馒头的营养特性。     

玉米提取物抑制亚硝化反应的研究

研究在体外模拟胃液条件下，玉米各部位提取物对亚硝酸胺合成的阻断作用和对亚硝酸盐的清除作用。结果显示：玉米各部位提取物均有较好的抑制亚硝化反应及阻断亚硝胺合成的作用，其阻断和清除率随提取物浓度的增加而增加。其中，玉米须对N-亚硝胺合成的阻断及亚硝酸盐的清除最佳，依次为玉米叶、玉米芯，玉米粒最次。     

Effect of corn particle size on site and extent of starch digestion in lactating dairy cows

Two experiments were conducted to determine the effects of corn particle size (CPS) on site and extent of starch digestion in lactating dairy cows. Animals were fitted with ruminal, duodenal, and ileal cannulas. Dry corn grain accounted for 36% of dry matter intake. In experiment 1, 6 cows were used in a duplicate 3 x 3 Latin square design. Semiflint corn was used. Corn processing methods were grinding, medium rolling, and coarse rolling. The mean particle size of the processed corn was 730, 1807, and 3668 microm, respectively. Rumen digestibility of starch linearly decreased from 59% with ground corn to 36% with coarsely rolled corn. Similarly, small intestine digestibility linearly decreased with increased CPS, and consequently, the amount of starch digested in the small intestine was not affected by corn processing. In experiment 2, 4 cows were used in a 2 x 2 crossover design. Dent corn was used. Corn processing methods were grinding and coarse rolling. The mean particle size of the processed corn was 568 and 3458 microm, respectively. Rumen digestibility of starch decreased from 70% with ground corn to 54% with coarsely rolled corn. Small intestine digestibility of starch was not significantly affected by CPS, and the amount of starch digested in the small intestine tended to be greater for rolled than for ground corn. In both experiments, starch total tract digestibility decreased with increased CPS. In conclusion, CPS is an efficient tool to manipulate rumen degradability of cornstarch. In midlactation cows, the decrease in the amount of starch digested in the rumen between grinding and coarse rolling is partly compensated for by an increase in the amount of starch digested in the small intestine with dent genotype, but with semiflint genotype postruminal digestion is not increased and rumen escape starch is not utilized by the animal.     

中性蛋白酶水解条件对玉米蛋白酶水解产物抗氧化活性影响研究

采用中性蛋白酶水解玉米蛋白粉,对不同条件下制备的玉米蛋白酶解液的还原力进行了研究,并在此基础上用响应面分析法优化酶水解条件,得到最佳酶解工艺条件为:底物体积分数6.05%,酶解温度55.3℃,加酶量3.88%,p H 7.6。在此条件下,玉米蛋白粉酶解产物的还原力为0.41。试验结果表明,该条件下的酶解产物具有较强的抗氧化能力,在食品工业上有一定的应用价值。