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The influence of rice bran water-soluble hemicellulose on hydrolysis of fat by pancreatic lipase with and without bile salts was examined in vitro. Bile salts are required for emulsification of the oil. Three of the major salts found in human bile (sodium cholate, glycocholate, and taurocholate) were tested for emulsifying properties with and without rice hemicellulose. The lipase activity decreased with increased addition of hemicellulose to the bile salt-enzyme reaction mixture. The results suggest that rice hemicellulose affects lipase activity indirectly by rendering the bile salts less available for emulsification of the oil and subsequent hydrolysis by the lipase. 相似文献
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为探究不同种类大米的酿酒特性,以粳糯米、籼糯米、粳米和籼米4种大米为原料,采用绍兴工艺进行了酿酒实验,监测发酵过程中基本理化指标(乙醇体积分数、还原糖、总酸等)的动态变化,并对发酵液中醇、醛、酸、酯类挥发性风味物质的质量浓度进行分析。结果表明,采用粳糯米进行酿酒时易糖化,发酵速度较快,产乙醇速率高,后酵结束时醪液乙醇体积分数达到18%,且残糖质量浓度相对较高。发酵结束时,不同种类大米原料黄酒发酵液中的氨基酸主要是甜味氨基酸和苦味氨基酸,甜、苦、鲜、涩氨基酸质量浓度均存在显著性差异(p0.01);籼米发酵液中氨基酸质量浓度最高,其次是粳糯米;粳糯米发酵液的挥发性风味物质的质量浓度及醇类化合物质量浓度上有明显优势,而籼糯米酿造原酒的酯类化合物质量浓度最高。 相似文献
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从婴儿粪便和药品中筛选到耐酸和胆汁盐的2株双歧杆菌菌种,分别命名为Bi.bifidumWN 04与Bi.longumGB 03.在pH值2.0条件下培养2h后再于胆汁盐质量浓度1.0g/dL的条件下培养2h.2株菌在pH值分别为2.0和3.0的50mmol/L的磷酸盐缓冲液中存活率较高;在胆汁盐质量浓度分别为0.25,0.5,1.0g/dL和2.0g/dL,pH值为6.8的50mmol/L磷酸盐缓冲液中存活率也较高,胆汁盐耐受性没有明显区别.在4℃保存于新鲜牛乳中,Bi.bifidumWN 04能够在8周内保持最高活菌数[lg(CFU/mL)>9],其它菌种活菌数[lg(CFU/mL)]<8. 相似文献
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采用蒸馏水、2%NaOH和5%KOH从6月龄毛竹竹竿中分级抽提得到水溶性半纤维素HW和碱溶性半纤维素H1~H4。通过热重分析法在升温速率10℃/min条件下分析了这5种半纤维素的热解特性,并对快速热解区建立了一级反应动力学模型。毛竹半纤维素热解主要发生在180~400℃,失重33.91%~42.54%。在终止温度700℃时残渣率均较高,达到34.52%~51.31%。毛竹半纤维素组分活化能均较小,为26.068~51.938 kJ/mol。碱溶性组分的活化能大于水溶性组分的活化能,残留木素越多,半纤维素的活化能和终止温度时的残渣率就越高。 相似文献
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分别采用甲酯化-分子蒸馏法及直接分子蒸馏法去除米糠毛油中的游离脂肪酸。前者甲酯化反应的酯化率为96.4%,谷维素回收率为98.71%;分子蒸馏通过单因素试验确定的最佳条件为蒸馏温度120℃、预热温度80℃、内冷温度40℃、刮膜器转速400 r/min、进料流量3 m L/min,最终产品收率为83.4%,酸价0.14 mg KOH/g,脂肪酸甲酯的清除率为97.04%,谷维素总回收率为98.39%。后者直接分子蒸馏的最佳蒸馏温度为170℃,最终产品收率为87.9%,酸价0.44 mg KOH/g,游离脂肪酸的清除率为97.6%,谷维素回收率91.65%。2种方法对比,前者虽步骤较多,但蒸馏温度低,谷维素损失少,因此更具优势。 相似文献
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以合理高效利用造纸工业的废弃物蔗髓为出发点,采用超声波辅助稀碱法分离蔗髓半纤维素。首先确定蔗髓的化学组分,然后通过单因素实验,分别考察超声波处理时间、KOH质量分数和碱液浸提温度对蔗髓半纤维素得率的影响,并应用响应面分析法对分离工艺进行优化。结果表明,超声波辅助碱提取蔗髓半纤维素的最佳提取工艺参数为:超声波处理时间28 min、KOH质量分数3.7%、碱液浸提温度53℃,在该条件下,半纤维素的总得率为23.05%,比无超声波辅助时提高了3.24个百分点。KOH质量分数、超声波处理时间和碱液浸提温度对半纤维素总得率影响均显著。 相似文献
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ABSTRACT: Light-colored, dry collagen was obtained and, after dissolving in warm water, turned into soluble gelatin. The type of acid used influenced the gelatin viscoelastic and gelling properties. Acetic- and propionic-acid extracts produced the gelatins with the highest elastic modulus, viscous modulus, melting temperature, and gel strength, especially when skins were previously treated with dilute NaOH. After such treatment, lactic acid was also shown to be suitable for collagen or gelatin extraction. The lowest degree of turbidity was achieved by using citric acid, whereas propionic acid led to the most turbid gelatin. No improvements of rheological properties were observed when acid concentration for extraction was increased above 0.05 M. 相似文献
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本研究以毛竹为原料,首先通过碱性过氧化氢法制备半纤维素,再采用超声辅助法对半纤维素进行羧甲基化改性。结果表明,液固比20∶1时半纤维素得率最高,达18.00%。半纤维素羧甲基化改性的最佳工艺条件为:NaOH物质的量浓度1.2 mol/L,氯乙酸物质的量浓度0.6 mol/L,碱化时间及温度分别为40 min、30 ℃,醚化时间及温度分别为150 min、70 ℃。随着羧甲基半纤维素取代度的提高,改性前后的半纤维素最大降解温度由257 ℃提升至300 ℃,说明羧甲基化改性有助于提升半纤维素的热稳定性;Zeta 电位的绝对值由9.98 mV提升至38.00 mV(取代度=0.59),且改性后半纤维素的分散性有了明显提升。 相似文献
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Physicochemical Properties and Eating Qualities of Milled Rice from Different Korean Elite Rice Varieties 总被引:1,自引:0,他引:1
Mi-Young Kang Catherine W. Rico Chae-Eun Kim 《International Journal of Food Properties》2013,16(3):640-653
Physicochemical properties and palatability of rice from six elite varieties in Korea (Chucheongbyeo, Saechucheongbyeo, Mihyangbyeo, Hitomebore, Nampyeongbyeo, and Ilpumbyeo) were analyzed. All samples, which contained 17–18 g/100 g rice starch amylose, belong to low-amylose rice group. Hitomebore variety showed abundant amount of essential amino acids, highest palatability score (82.9), and lowest mineral content. The rice samples contained relatively similar concentrations of saturated (21–24 g/100 g rice) and unsaturated (75–78 g/100 g rice) fatty acids. Mihyangbyeo variety exhibited the highest amount of protein (8.10 g/100 g rice), sugar content, and pasting temperature (82.75°C) and time (3.78 min), but lowest viscosity values. Ribose, rhamnose, and potassium were found to have negative correlations with palatability and breakdown viscosity, indicating that gelatinization characteristics could also be used in evaluating the eating quality of rice. Results of this study could assist plant breeders in developing rice varieties with improved genetic traits and high eating quality. 相似文献
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胆汁酸在药物和食品领域的研究进展 总被引:2,自引:0,他引:2
胆汁的主要成分胆汁酸,在生物体内发挥着重要的生理功能。同时,作为一种生物表面活性剂,胆汁酸可以形成胶束、囊泡等多种具有药物载体开发价值的超分子自组装体结构。本文综述近年药品和食品领域胆汁酸的研究进展,并提出它在药物载体研究领域具有巨大的发展潜能。 相似文献
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为了研究浸泡处理对糯米理化特性的影响,本文选用三种糯米样品,观测了其基本理化指标和粘度曲线等特性。测定浸泡(20℃~35℃)过程中糯米米粒水分含量的变化和最终的含水量,采用Peleg方程拟合糯米的吸水动力学特性,并对糯米浸泡前后红外光谱和X-射线衍射图谱的进行分析比较。研究发现越南米和长江米吸水量大,其最终含水量分别达到36.34%(20℃)和34.64%(28℃),温度对其影响较小;黑香米吸水速度和数量较小,最终含水量为31.99%(35℃),且温度对其影响较大;其次,可运用Peleg方程米对浸泡过程中糯米的近似水分含量进行预测。浸泡前后糯米的红外光谱在1047cm-1与1022cm-1峰的强度比值在0.89~0.92之间,无显著差异。X-射线衍射表明水分子主要进入糯米颗粒内的无定型区和亚结晶区,越南米和长江米样品的亚结晶区变小,黑香米则有所增大。本文研究可为米粉的加工提供理论指导。 相似文献
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初步探究了8种新型溶剂体系处理对棉秆半纤维素的分离效果。结果表明,基于不同溶剂体系处理棉秆,再经二甲基亚砜(DMSO)抽提,可实现半纤维素组分的分离;由于处理体系性质不同,导致分离所得半纤维素的结构差异较大。其中,碱性溶剂体系分离得到的半纤维素纯度较好,主要由聚木糖组成,同时含有一定量来源于木糖聚葡萄糖的葡萄糖;而采用近中性体系,如八丁基氟化铵/二甲基亚砜、1-烯丙基-3-甲基咪唑氯盐/二甲基亚砜、1,3-二甲基丙撑脲/二甲基亚砜及N-甲基吗啉氧化物/二甲基亚砜分离得到的半纤维素中含有大量来源于纤维素的葡萄糖,表明近中性溶剂体系不适宜用于高纯半纤维素的分离。 相似文献
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不同品种大米口感品质分析 总被引:4,自引:0,他引:4
以不同品种大米为研究对象,采用模糊感官评价结合质构仪分析及电子舌技术,对大米米饭口感品质 进行比较分析,建立一种米饭口感品质评价的方法。结果表明:模糊感官评价和质构特性分析中大粒香米饭口 感最佳,内优5H25米饭口感最差,大粒香、大粒溪香、金麻粘3 种米饭感官评分较接近且质构特性基本无显著差 异(P>0.05)。通过主成分分析,电子舌能很好地区分不同品种大米原料及米饭,其结果与模糊感官评价一致。 通过偏最小二乘回归分析建立米饭滋味评价模型,相关系数达到0.954 06,能很好地预测不同品种米饭的滋味。因 此,在大米口感品质评价中,感官评定结合电子舌的分析方法更易获得准确、可靠的结论。 相似文献
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《Food Reviews International》2013,29(3):217-230
Antioxidant properties and health benefits of hydroxycinnamic acids cause food technologists to apply them as additives to new functional foods. Meanwhile, many of these products contain significant amounts of proteins in the native form or added isolates and hydrolysates. In this type of food, interactions between hydroxycinnamic acids and proteins will inevitably occur. The effect of such interactions in designed food could be more important than in the processed natural raw food materials and can significantly decrease the bioavailability of hydroxycinnamic acids and proteins as well as antioxidant activity of the product. This review describes chemical mechanism of protein–hydroxycinnamic acid interactions and the effect of formed adducts on technological and nutritional properties of food. 相似文献