鹰嘴豆α-低聚半乳糖的肠道益生功能

以鹰嘴豆为材料,通过提取与活性炭-硅藻土柱层析分离纯化,制备鹰嘴豆粗提物和不同纯化程度的鹰嘴豆α-低聚半乳糖(α-GOS)样品。采用体外厌氧粪样混合培养与荧光原位杂交技术,评价鹰嘴豆α-GOS的益生功能。结果表明：鹰嘴豆α-GOS对肠道有益菌(双歧杆菌、乳酸菌)有较好的增殖作用,而对有害菌(拟杆菌、梭状菌)的生长有一定的抑制作用;鹰嘴豆α-GOS只是改变了肠道内菌体的组成,而对总体菌群的数量基本没有影响;α-GOS含量高于90%的鹰嘴豆α-GOS样品的益生指数(PI)最高(2.00),α-GOS含量为70%～80%、80%～90%的鹰嘴豆α-GOS样品及鹰嘴豆粗提物的PI值依次为1.39、1.73和0.89,而对照组(不加任何碳源的处理)为负值 (－0.29)。总之,鹰嘴豆α-GOS具有很好的肠道益生功能。     

低聚半乳糖糖基化法降低牛乳αs1-酪蛋白抗原性和免疫原性

用等电点沉淀法从牛乳中提取酪蛋白,根据αs-酪蛋白对尿素溶液溶解特性从酪蛋白中提取αs-酪蛋白,并用阴离子交换层析使αs1-酪蛋白与αs2-酪蛋白分离。用低聚半乳糖通过在一定条件下的美拉德反应对αs1-酪蛋白进行糖基化处理,通过竞争ELISA实验检测αs1-酪蛋白糖基化产物的抗原性。结果表明,该糖基化产物的抗原抗体结合常数Kd较αs1-酪蛋白上升3.7倍,即低聚半乳糖糖基化处理使αs1-酪蛋白的抗原性得到显著降低。用动物实验和非竞争ELISA实验检测αs1-酪蛋白糖基化产物的免疫原性,结果显示免疫原性降低19%,该实验证实对降低牛乳αs1-CN抗原性和免疫原性具有显著效果,为开发较理想的、切实可行的新脱敏奶粉生产技术提供了科学依据。     

不同模式体系美拉德反应程度及抗氧化活性比较

以葡萄糖、果糖、蛋氨酸、甘氨酸、精氨酸和大豆分离蛋白为美拉德反应原料,研究加热时间和混合比例对褐变程度的影响,并对褐变程度最强的产物进行抗氧化活性检测。结果表明：葡萄糖、果糖分别与甘氨酸按物质的量之比2:1混合(pH9.0),并于100℃恒温水浴锅中加热180min时褐变程度最强。葡萄糖-甘氨酸与果糖-甘氨酸模式体系的美拉德反应物都具有一定的抗氧化能力。在相同体积分数条件下,果糖-甘氨酸模式体系的美拉德反应物的还原能力和抗氧化值均要强于葡萄糖-甘氨酸模式体系的美拉德反应物。葡萄糖-甘氨酸模式体系的美拉德反应物对 ·OH和O2 ·的抑制率最高分别达50.65%和45.42%,而果糖-甘氨酸模式体系的美拉德反应物对 ·OH和O2 ·的抑制率最高则分别达57.55%和28.54%。     

鹰嘴豆蛋白酶解物美拉德风味肽制备工艺的研究

利用鹰嘴豆蛋白酶解液,通过美拉德模式体系制备风味肽产品。采用均匀实验设计,得出模式美拉德反应体系最佳条件和配方为:鹰嘴豆蛋白酶解液添加量10.0 g,反应温度86℃,时间30 min,p H9.0,L-半胱氨酸0.12 g,L-丙氨酸0.12 g,L-谷氨酸0.01 g,I+G 0.01 g,D(+)-木糖1.08 g,VB10.12 g。同时研究中发现,添加不同水解度鹰嘴豆蛋白酶解液对所制备的风味肽产品风味具有显著的影响(p0.001),当水解度为23.03%~26.02%时,对模式美拉德体系制备的风味肽整体香气具有显著的提升作用。     

影响美拉德反应的几种因素研究

本文研究了加热温度、加热时间、反应体系pH、5种糖类及金属离子对美拉德颜色反应的影响。实验表明在一定条件下,温度越高、时间越长美拉德反应的颜色越深,pH低于7.0时反应不明显,当pH7.0时美拉德反应的速度加快。5种糖的反应活性依次为木糖﹥半乳糖﹥葡萄糖﹥果糖,蔗糖无明显反应。Fe3+、Fe2+能促进美拉德反应,且Fe3+比Fe2+更能促进反应颜色的加深;Ca2+、Mg2+对美拉德反应起抑制作用,且Mg2+比Ca2+抑制作用强;K+对美拉德反应影响相对较小。     

葡萄糖-牡蛎酶解液美拉德反应体系的抗氧化活性

以牡蛎酶解液与葡萄糖建立美拉德反应体系,以1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl, DPPH）自由基清除率、金属离子螯合能力和还原能力为指标,通过葡萄糖质量分数、反应温度、pH值以及反应时 间4 个因素的单因素试验和正交试验优化得到具有强抗氧化活性的美拉德反应产物适宜反应条件。结果表明,葡萄 糖-牡蛎酶解液美拉德反应产物具有较强抗氧化活性的反应条件为葡萄糖质量分数4%、反应温度120 ℃、pH 7.0、 反应时间120 min。在此组合条件下,牡蛎酶解液美拉德反应得到的反应液的DPPH自由基清除率为93.2%,金属离 子螯合能力为22.5%,还原能力为1.436。     

酪蛋白酸钠美拉德反应产物的制备及其乳化特性

利用小型超高温设备制备酪蛋白酸钠与葡萄糖、乳糖、低聚半乳糖、聚葡萄糖的美拉德反应产物,对比分析不同分子质量糖在不同热处理时间的美拉德反应进程及产物的乳化特性。结果表明,小分子质量的糖更易发生美拉德反应,褐变指数与反应程度呈正相关,乳化活性与接枝度均呈现先增大后减小的趋势,但两者并不成线性关系,酪蛋白酸钠与葡萄糖、乳糖、低聚半乳糖、聚葡萄糖乳化活性达到的最大值分别为0.63、0.51、0.55和0.48,其中130?℃热处理15?s的酪蛋白酸钠-葡萄糖溶液乳化活性最大,高于其他组,与水浴90?℃热处理90?min相当,并且乳化稳定性也呈现较高的水平,为123.88?min,将其用作乳化剂制备的DHA藻油乳状液稳定性动力学指数为1.5,显著小于其他组（P＜0.05）;由此可见,葡萄糖可作为美拉德反应的优良糖基配体制备新型高效的乳化剂,并且此方法可实现连续化生产,极大缩短了反应时间,提高了生产效率,对工业化生产具有指导意义。     

干热条件下壳聚糖-葡萄糖的美拉德反应

壳聚糖含有丰富的氨基,可与葡萄糖发生美拉德反应。本文就干热条件下壳聚糖与葡萄糖发生美拉德反应的可能性进行了初步研究,确定了两者发生美拉德反应的最佳反应条件,并对美拉德反应产物的热性能和流变学性质进行了表征。结果显示,壳聚糖与葡萄糖在干热条件下易于发生美拉德反应,且最适的反应条件为反应温度90℃、相对湿度61.0%、反应时间6h、壳聚糖/葡萄糖混合比例1.5∶1。在此条件下制备的美拉德反应产物的热性能和流变学性质均发生了明显改变,进一步证实了壳聚糖与葡萄糖之间发生了美拉德反应。     

湿热条件下低聚木糖-乳清分离蛋白的美拉德反应及产物乳化性与流变性研究

本文研究了湿热条件下不同混合质量比(1:1、1:2、1:3、1:4,W/W)对低聚木糖与乳清分离蛋白(WPI)美拉德反应及其产物的乳化性与流变性的影响。UV-Vis吸光度值,pH和粒径大小显著变化表明,该条件下成功制备了WPI和低聚木糖的美拉德反应产物 (MRPs)。数据显示,质量比为1:2的溶液体系美拉德反应程度最高;与未经过美拉德反应的体系相比,MRPs的平均粒径均减小而质量比为1:2的体系平均粒径最大;同时,美拉德反应提高了WPI的乳化活性和乳化稳定性,比例为1:2时MRPs具有最佳的乳化活性(38.63 m2/g)和乳化稳定性(65.23%);流变学测试表明糖基化修饰增强了WPI的凝胶性,比例为1:3时MRPs的储存模量提高最大,G''值高达约97,000 Pa (约WPI的7倍);在相同剪切速率下,MRPs溶液的表观粘度增加,而WPI的添加比例对体系粘度的影响占主导作用。上述研究表明,美拉德反应可改善WPI的乳化特性和凝胶特性。     

黄鲫蛋白抗菌肽—葡萄糖美拉德反应物的抑菌性实验研究

利用响应面分析法优化黄鲫蛋白抗菌肽-葡萄糖美拉德反应条件,提高产物的抑菌活性。以大肠杆菌为指示菌,在黄鲫蛋白抗菌肽初始反应pH为5.58条件下,进行葡萄糖添加量、加热温度和加热时间三因素三水平Box-Benhnken响应面分析实验,得出黄鲫蛋白抗菌肽-葡萄糖美拉德反应最优条件为葡萄糖添加量0.25%(w/v)、加热温度100℃、加热时间60 min。在最优反应条件下,黄鲫蛋白抗菌肽-葡萄糖美拉德反应物对大肠杆菌的抑菌圈直径为28.9 mm,与理论值28.4 mm接近。     

Determination of oligosaccharide contents in 19 cultivars of chickpea (Cicer arietinum L) seeds by high performance liquid chromatography

The extraction procedure of oligosaccharides from chickpea seeds was optimized and sufficient extraction was achieved with 50% of ethanol-water in a ratio of 10:1 for solvent to defatted chickpea meal at 50 °C for 30 min. Under the optimal extraction conditions, the contents of oligosaccharides in 19 cultivars of chickpea seeds were determined by HPLC. The results showed that the main α-galactooligosaccharides (α-GOS) in chickpea seeds were raffinose, stachyose, verbascose and an unknown glycoside, which was isolated, purified, and identified as ciceritol. Ciceritol, the main sugar in all the chickpea samples, accounted for about 50% of the total α-GOS. There were considerable variations in the levels of α-GOS and sucrose between species, especially verbascose which could only be detected in 7 samples. With the highest amount of α-GOS and a low amount of sucrose, the 171 was the best choice for obtaining α-GOS for use as a prebiotic in functional foods.     

Glycation and phosphorylation of α-lactalbumin by dry heating: Effect on protein structure and physiological functions

α-Lactalbumin (α-LA) was glycated with maltopentaose (MP) through the Maillard reaction (MP-α-LA) and subsequently phosphorylated by dry heating in the presence of pyrophosphate to investigate its structure and physiological functions. Glycation occurred effectively, and the sugar content of α-LA increased by approximately 22.3% through the Maillard reaction. The phosphorylation of MP-α-LA was enhanced with an increase in the dry-heating time from 1 to 5 d, and the phosphorous content of MP-α-LA increased by approximately 1.01% by dry heating at pH 4.0 and 85°C for 5 d in the presence of pyrophosphate. The electrophoretic mobility of α-LA increased with an increase in the phosphorylation level. The circular dichroism spectra showed that the change in the secondary structure of the α-LA molecule by glycation and subsequent phosphorylation was slight. However, the Trp fluorescence intensity was increased by phosphorylation after glycation. In addition, the differential scanning calorimetry thermograms of α-LA showed that the denaturation temperature of MP-α-LA was decreased by phosphorylation. These results indicated that molten (partially unfolded) conformations of α-LA were formed by dry heating in the presence of pyrophosphate after glycation. The anti-α-LA antibody response was significantly reduced by glycation and subsequent phosphorylation. The suppressive effect of α-LA on the production of proinflammatory cytokines such as IL-6 and tumor necrosis factor-α from THP-1 cells after stimulation with lipopolysaccharide was significantly enhanced by glycation with MP and was further enhanced by phosphorylation after glycation. The Ca phosphate-solubilizing ability of α-LA was enhanced by phosphorylation. The apoptotic activity of α-LA was reduced by glycation and subsequent phosphorylation. These results suggest that phosphorylation by dry heating in the presence of pyrophosphate after glycation with MP through the Maillard reaction is a useful method for improvement of the physiological functions of α-LA.     

Study on the Maillard Reaction Enhanced by Pulsed Electric Field in a Glycin�CGlucose Model System

Effects of pulsed electric field (PEF) on glycin and glucose content, browning value, and antioxidant activity of a glycin–glucose solution were explored. Results showed that at PEF intensity of 40 kV/cm, the solution’s absorbance at 420 nm was significantly increased from 0 to approximately 0.17 after 7.35-ms treatment. The temperature of PEF-treated samples was overall lower than 40 °C. It was also detected that the antioxidant activity of treated sample was increased to 39.36%. Moreover, 13.09% glycin and 50.76% glucose were consumed during the Maillard reaction in this experiment. This study indicates that pulsed electric field treatment, especially with higher intensity over 30 kV/cm, is a promising method to significantly promote the Maillard reaction in glycin–glucose solution.     

Maillard reaction during storage of powder enteral formulas

Mono- and disaccharide compositions and Maillard reaction development in four powder enteral formulas were determined. Also, a study of the changes in this carbohydrate fraction as well as the progress of Maillard reaction during storage of two samples, under different temperature and time conditions and water a activity of 0.44, was carried out.Variable amounts of fructose, glucose, lactose, sucrose, maltose and maltulose were detected in the studied samples. Furosine (ε-2-furoylmethyl lysine), was present in the four enteral samples studied whereas 2-furoylmethyl alanine (2-FM-Ala) and α-2-furoylmethyl lysine were only present in two samples.Storage at 30 and 50 °C produced slight changes in carbohydrate composition. At the two temperatures assayed the same level of carbohydrate was found at the end of storage period studied. The maltose/maltulose ratio did not suffer notable changes under moderately-severe conditions of storage. Furosine, 2-FM-Ala and α-2-furoylmethyl lysine content increased during storage, and the formation of 2-furoylmethyl arginine was detected in one stored sample.Results seem to indicate that 2-furoylmethyl derivatives of lysine, alanine and arginine could be used as good indicators of storage conditions of powder enteral formulas. Moreover, the maltose/maltulose ratio may be a quality indicator of the processing conditions during manufacture of commercial enteral products.     

A pulsed electric field procedure for promoting Maillard reaction in an asparagine–glucose model system

Effects of pulsed electric field (PEF) on pH, intermediate products, asparagine and glucose content, browning value, reducing power as well as antioxidant activity of an asparagine–glucose solution were explored in this paper. Results showed that the solution’s UV–Vis absorbance at 294 nm and 420 nm was significantly increased from 0 to approximately 1.14 and 0.74, respectively, at PEF intensity of 40 kV cm^?1 for 7.35 ms treatment. The temperature of PEF treated samples were overall lower than 40 °C. It was also detected that the antioxidant activity of treated sample was correspondingly increased by 20.33%. Meanwhile, 14% reduction of asparagine content and 66% reduction of glucose content were observed. It was demonstrated from high performance liquid chromatography analysis that Maillard reaction in the model system had been enhanced by PEF treatment as no 5‐hydroxymethyl‐2‐furaldehyde was generated. This study indicates that pulsed electric field treatment, especially with higher intensities, is a means to significantly promote the Maillard reaction in an asparagine–glucose solution.     

超高压诱导β-乳球蛋白-壳聚糖共价复合物及其稳定乳状液的制备与表征

目的：探究超高压处理对美拉德反应的影响，通过蛋白质-多糖共价复合物反应，开发更高效的油-水界面膜以提高乳液稳定性。方法：以不同质量比（1∶1、1∶2、1∶4）的β-乳球蛋白和壳聚糖为原料，经不同压力（200、400、600 MPa）处理后，进行干法美拉德反应，以β-乳球蛋白和壳聚糖的物理混合物为对照，研究产物的褐变程度、荧光光谱和圆二色光谱图，以及制备的乳液粒径、Zeta-电位、物理稳定性等。结果：蛋白与多糖质量比为1∶1和1∶2时，随压力增加，褐变程度先升高后降低；蛋白与多糖质量比为1∶4时，褐变程度随压力增加持续升高。超高压诱导的美拉德反应使蛋白质荧光发生猝灭，壳聚糖比例越高，猝灭程度越大。在蛋白与多糖不同质量比（1∶1、1∶2、1∶4）时，共价复合物的α-螺旋相对含量分别由19.5%、21.1%、22.5%（物理混合物）降至18.7%、16.9%、15.9%，共价复合物α-螺旋相对含量均在400 MPa达到最大值，分别为19.6%、19.0%、16.6%。蛋白与多糖共价复合物制备的乳液粒径（399.1、481.5、584.4 nm）以及4 h时稳定性动力学指数（1.60、2.31、0.49）均比其物理混合物要小，而Zeta-电位更高（46～48 mV），乳液更稳定。结论：超高压诱导美拉德反应对其产物乳液的乳化稳定性有积极影响。     

The effect of glycation on foam and structural properties of β-lactoglobulin

The goal of the present work was to evaluate whether the Maillard reaction, with glucose and lactose as substrates, improves the foaming properties of β-lactoglobulin. Lactose led to the lowest degree of modification without significant differences by reaction time and by protein:sugar molar ratio. However, in the case of glucose, the degree of glycation increases with reaction time and molar ratio. The results obtained by UV fluorescence, surface hydrophobicity and differential scanning calorimetry clearly showed differences in the degree of folding of β-lactoglobulin upon modification with different sugars or thermal treatment, with changes in the foaming capacity of β-lactoglobulin. All the modified samples exhibited a significant increase (α ? 0.05) in draining stability (Kg) as compared to the non-thermally treated sample. In addition, foams formed by lactose-glycated samples were more stable than those formed by glucose-glycated ones. A significant increase (α ? 0.05) of foam stability with reaction time was also detected, particularly in glucose-glycated samples.