甜菜果胶理化性质及加工适用性质研究

本文对甜菜果胶(SBP)的各项理化性质进行了研究,并与商品柑橘果胶(CP)进行对比。研究了果胶中半乳糖醛酸、总糖、蛋白质含量,酯化度,乙酰度等基本理化性质。然后通过傅里叶红外光谱扫描、果胶分子量等指标,研究了甜菜果胶分子结构的基本特性。通过乳液粒径,乳化活性,ζ-电位和显微观察的手段,对其乳化性质进行评价。最后从流体力学性质出发,考察了果胶浓度和温度对其表观黏度的影响。发现甜菜果胶中蛋白质和阿魏酸含量较高,分子量和表观黏度较柑橘果胶更小。且甜菜果胶的乳化性质优于牛血清白蛋白和阿拉伯胶。通过该研究明确了甜菜果胶的加工适应性,同时为进一步研究甜菜果胶的乳化及凝胶特性提供了理论依据。     

不同月份豆腐柴叶果胶理化性质差异研究

为探究不同月份豆腐柴叶果胶特性差异,寻求不同月份"树叶凉粉"品质参差不齐的原因,提高豆腐柴叶果胶的应用价值,本文主要采用主成分分析法综合评价了不同月份(5~10月)豆腐柴叶果胶得率、主要成分、粘均分子量、乳化性、凝胶性等理化性质。结果表明:果胶得率为4.24%~18.24%,5~9月得率高于15%;半乳糖醛酸含量为73.73%~81.96%,6~9月含量较高;5~9月粘均分子量随月份增加呈增大趋势,10月有所降低。5~8月得到的果胶粉末呈淡黄色,9月和10月呈淡黄夹灰白色。乳化活性和乳化稳定性均高于50%,优于橘皮果胶标品;凝胶特性差异明显,7~9月果胶凝胶性能良好。综合评分从高到低为:9月 > 7月 > 8月 > 10月 > 6月 > 5月,说明不同月份豆腐柴叶果胶品质差异较大,7~9月豆腐柴叶果胶综合得分明显高于其他月份,更适合于果胶的提取利用。     

乳清分离蛋白-甜菜果胶共价复合物理化特性分析

蛋白质-多糖通过Maillard反应生成共价复合物,其乳化稳定性等功能特性得到提高,为研究与开发新型食品添加剂提供了一条新的途径,但共价复合物的乳化稳定性提高机理尚不明确。本研究通过界面张力仪测定界面张力、红外光谱分析二级结构,并结合GPC-动态光散射法考察其分子量分布,初步探讨乳清分离蛋白(WPI)-甜菜果胶(BP)共价复合物乳化稳定提高原因。研究结果表明:WPI-BP共价复合物与混合物相比,界面张力降低;WPI-BP共价复合作用使得蛋白质分子中的羟基含量增加,亲水性增强;共价复合物的分子量增大,dn/dc降低,分子量分布更集中,提高其在乳状液界面上的空间位阻作用,从而提高其乳化稳定性。因此,界面张力降低、亲水性增强与空间位阻增大是WPI-BP共价复合物乳化稳定性提高的主要原因。     

山楂生、炒品果胶结构表征和体外降脂作用研究

目的 明确山楂生品果胶(raw hawthorn pectin, RHP )和炒品果胶(fried hawthorn pectin, FHP)的结构与其体外降脂作用的关系。方法 通过测定酯化度、半乳糖醛酸含量、分子量、特性黏粘度、黏均分子量、中性糖组成和比例,用扫描电镜观察微观形态,来表征RHP和FHP的结构。 通过果胶对胆固醇胶束和胆酸盐的结合能力等体外实验评价其降脂作用。结果 RHP酯化度为52.19%,属于高酯果胶;FHP酯化度为31.95%,属于低酯果胶。RHP和FHP的半乳糖醛酸含量分别为78.54%和48.42%。RHP分子量有4个级分(217904、16907、8933、5104 Da),FHP分子量有4个级分(238813、16662、8770、5063 Da)。RHP特性黏粘度和黏均分子量分别为0.10 dL/g和2.75×104 g/moL,FHP特性黏度和黏均分子量分别为0.16 dL/g 和4.71×104 g/moL。RHP、FHP均含有葡萄糖、鼠李糖、半乳糖、果糖和木糖等中性糖,但各糖的分子摩尔比不同。微观形态中,RHP分子间交联良好;FHP分子之间交联较少。在体外降脂实验中,RHP对胆固醇胶束和胆酸盐结合能力强于FHP。结论 山楂炒制后,果胶的特性黏粘度和黏均分子量升高;分子量分布无明显变化,部分级分分子量降低;果胶的交联程度、半乳糖醛酸含量、酯化度降低,体外降脂作用降低。炒制使果胶结构发生了改变从而影响其降脂作用。     

超声处理对葡萄细胞壁果胶组分的影响

为明确超声处理下葡萄细胞壁中不同果胶组分含量及结构变化，本研究采用不同超声时间和超声功率对葡萄进行处理，通过咔唑硫酸法、PMP柱前衍生化法、高效液相凝胶色谱分析、扫描电子显微镜、傅里叶变换红外光谱分析和圆二色谱分析等手段分析了葡萄细胞壁中果胶组分含量、单糖组成及结构变化。结果表明，新鲜葡萄细胞壁果胶中碱溶性果胶含量最高，为27.41 mg/g AIR，螯合型果胶含量最低，为8.25 mg/g AIR；不同超声处理后总果胶含量呈下降趋势，其中水溶性果胶含量增加，螯合型和碱溶性果胶含量降低。果胶单糖共检测到6种，不同果胶组分单糖组成不同，水溶性果胶中半乳糖和阿拉伯糖含量较高，螯合型果胶中葡萄糖醛酸含量最多，而碱溶性果胶中含量最高的为鼠李糖；超声处理后果胶组分单糖组成不变，但含量均发生降低；超声作用未改变果胶主链结构，但其线性结构和支链程度均发生变化。随着超声处理时间和功率的增加，不同果胶的分子量整体均呈下降趋势，并且在微观结构上呈现更加松散形态。此外，超声作用对果胶组分特征官能团影响较小，但对螯合型果胶和碱溶性果胶分子的结构和链构象产生作用，使其最大响应值发生移动，并且超声功率作用影响更大...     

甜菜果胶乳化活性及稳定性

甜菜果胶是一种从甜菜粕中提取的酸性阴离子多糖,主链由鼠李糖和半乳糖醛酸组成,侧链数量丰富,主 要由鼠李糖、阿拉伯糖、半乳糖、果糖等一些中性糖组成。其中中性糖末端与蛋白质共价连接,赋予了甜菜果胶 良好的乳化性质。本研究主要探究了甜菜果胶的乳化特性并与柑橘果胶进行对比。考察了甜菜粕产地、果胶质量 浓度、pH值、温度、贮藏时间等对乳液特性（粒径分布、平均粒径、Zeta-电位和浊度变化）的影响。研究结果表 明,产地不同对甜菜果胶结构组成影响较大,以甜菜果胶制备的乳液粒径显著小于柑橘果胶乳液,且乳化活性更 高。当甜菜果胶质量浓度为10～25 mg/mL时,乳液在4 周的贮存期内保持良好的稳定性,而柑橘果胶乳液粒径显著 增加。pH 2～6的范围内,果胶粒径基本保持不变。25～85 ℃升温过程中,柑橘果胶乳液粒径大幅增加。说明甜菜 果胶具有良好的乳化活性和稳定性。本研究为甜菜果胶的实际应用提供了理论指导。     

甜菜废丝中果胶的分离及特性

采用不同的溶剂分离法从甜菜废丝中提取果胶。最佳的盐酸萃取法(HCl)可从原料中提取出19.53%的果胶。HCl分离的果胶含有81.8%的半乳糖醛酸。各种方法提取的甜菜废丝果胶都有高含量的甲氧基(≥60%程度的甲基化)。果胶中还含有10—17.5%的中性糖,据气相色谱分析,其主要为阿拉伯糖和半乳糖。用凝胶渗透作用测定果胶分子量的峰值为35,500～44,700道尔顿。该果胶的持水性高、粘度低。     

不同分子量段巢脾多糖理化性质及其抗氧化活性分析

采用超滤法对巢脾多糖进行分级分离,获得分子量为4 kDa~10 kDa(HCP-1)、10 kDa~50 kDa(HCP-2)、50 kDa~100 kDa(HCP-3),大于100 kDa(HCP-4)4个不同分子量段的巢脾多糖,对4个分子量段巢脾多糖的理化性质和抗氧化活性进行分析。结果显示巢脾多糖中蛋白质含量随着分子量的增大而增高,还原糖含量则随着分子量的增大而减小;各分子量段巢脾多糖紫外及红外光谱特征相似,而单糖组成及含量差异较大,HCP-3及HCP-4中单糖种类及含量相比于HCP-1及HCP-2都较为丰富。体外抗氧化活性分析结果显示,在一定浓度范围内,各分子量段多糖对超氧自由基、羟自由基清除能力及总抗氧化能力与多糖浓度呈明显的量效关系,其中HCP-4的抗氧化活性最强。     

不同品种枣果中果胶含量、中性单糖组成及分子质量分布

以我国6种枣果为原料,采用柱前衍生结合气-质联用测定6种枣果中3种类型果胶的含量、中性单糖组成,同时采用高效凝胶渗透色谱测定3种类型果胶的分子质量分布。结果表明:6种枣果中均以水溶性果胶(WSP)含量最高,溶于Na_2CO_3型果胶(SSP)次之,螯合性果胶(CSP)含量最低;WSP、CSP和SSP中性单糖受枣果来源不同影响,其中WSP和SSP主要中性单糖为阿拉伯糖、鼠李糖、半乳糖和葡萄糖;而CSP的主要中性单糖为阿拉伯糖、葡萄糖和岩藻糖。果胶的分子质量分布受枣果品种来源和果胶类型两方面影响,其中"金丝小枣"与"木枣"WSP的分子质量分布明显宽于其余4个品种枣果WSP的分子质量分布;"金丝小枣"和"灰枣"中CSP分子质量分布比其余4个品种枣果的分子质量分布更加集中,而且主要集中在高分子端。     

果胶提取工艺对甜菜粕物化性质的修饰作用研究

本文研究了提取溶剂对甜菜粕结构、形貌的修饰作用。甜菜粕结构致密,表面由无规则褶皱组成。经草酸铵溶液处理后(80℃,pH 5.2,浸提2遍),甜菜粕中的钙离子含量由1.28%降至0.81%,且甜菜粕具有疏松多孔状的表面形貌,但甜菜粕主要的官能团及结晶结构并未发生变化。在热酸作用下(80℃,pH 1.5),甜菜粕中的原果胶逐渐转化为可溶性果胶;此时,甜菜粕的光谱信息也发生相应的变化,表现为2930 cm-1的红外光谱吸收峰变强、相对结晶度增加。溶解于草酸铵的甜菜果胶得率为2.6%,而酸溶性甜菜果胶得率中为13.1%;所有甜菜果胶提取物均富含半乳糖醛酸、中性糖。研究结果表明,草酸铵能解除钙离子对部分甜菜果胶的束缚,并降低甜菜粕的致密度;稀酸对甜菜粕具有强修饰作用,不仅能溶解甜菜果胶及细胞壁中的钙离子,还能显著提高甜菜粕的相对结晶度。     

Optimisation of production yield by ultrasound‐/microwave‐assisted acid method and functional property of pectin from sugar beet pulp

Response surface methodology was used to optimise pectin recovery from sugar beet pulp using ultrasound‐/microwave‐assisted acid method (UMAAM). The independent variables were microwave heating temperature, microwave heating time and solid‐to‐liquid ratio. From the results, the selected optimal conditions were 92 °C, 37 min, and solid‐to‐liquid ratio 1:30. Under these conditions, the yield and uronic acid content of the pectin (SBP1) was 26.16% and 75.38%, respectively. Compared with the sugar beet pectin (SBP2) extracted by traditional acid method, SBP1 showed a higher molecular weight, higher viscosity and emulsifying activity and stability. The possible reason was that the UMAAM could have had minimal change in the protein–polysaccharide complex structure of pectin, but significantly increased the length of polysaccharide chains compared with SBP2. These results suggested that UMAAM is an efficient method in extracting pectin and has the potential to be used in the sugar beet industry.     

Preparation of environment‐friendly pectin from sugar beet pulp and assessment of its emulsifying capacity

This study was designed to prepare environment‐friendly pectin from sugar beet pulp (SBP) using subcritical water combined with ultrasonic treatment. Plackett–Burman design based on nineteen different parameters was applied to study the influence of various factors on the characteristics of sugar beet pulp pectin (SBPP). About 29.1% pectin, 62% degree of methylation (DM) and 36% acetylation (DA), and 42.5‐kDa average molecular weight (AMW) were obtained from SBP when using distilled water with solid/liquid ratio of 1:81 for extraction at 110 °C. The yield of SBPP and galacturonic acid (GalA) was mainly affected by solid/liquid (S/L) ratio, water purity and extraction temperature. The ultrasonic temperature, ultrasonic power and extraction temperature were the main factors effecting on neutral sugar content, DM, DA and AMW. Compared with gum arabic (GA), the highest yield SBPP fraction had better emulsifying activity, but poorer emulsion‐stabilizing ability.     

Emulsifying and structural properties of pectin enzymatically extracted from pumpkin

The present study investigated the emulsifying and structural properties of pectin enzymatically extracted from pumpkin. Pumpkin pectin fraction A was obtained from raw pumpkin with an enzymatic preparation of cellulase and α-amylase. Pumpkin pectin fraction B was achieved by treating the fraction A solution with pronase to reduce protein content. According to the findings (on protein content, galacturonic acid content, neutral sugar composition, and molecular weight distribution), the pronase treatment could remove protein from the fraction A without considerably influencing any other chemical and molecular properties. Moreover, the fraction A exhibited emulsifying properties in water and oil mixture, whereas the removal of protein in the fraction B resulted in the loss of emulsifying properties. The FT-IR and 1D NMR analysis revealed that the backbone of pumpkin pectin is mainly composed of α-1,4-d-galacturonic acid in which a considerable portion of galacturonic acid residues is present as methyl esters, and some l-rhamnose are involved in the linear region of the backbone through α-1,2-linkages.     

Preparation and characterisation of surface‐active pectin from soya hulls by phosphate‐assisted subcritical water combined with ultrasonic treatment

Surface‐active pectin was efficiently extracted from soya hull using phosphate‐assisted subcritical water combined with ultrasonic treatment (PASW‐UT). The physicochemical and functional properties of soya hull pectin (PSHP) were evaluated. Compared to pectin prepared by traditional acid extraction (ASHP), the yield and purity of PSHP were significantly increased, as well as PSHP also contained more protein moiety and displayed better emulsifying and foaming properties. However, the emulsifying and foaming properties of protein‐depleted soya bean hull pectin (PDSHP) were markedly decreased as compared to PSHP, which was supported by data of dynamic interfacial tension of pectins, suggesting that the emulsifying and foaming capacity of PSHP should be mainly ascribed to the existence of more extensin, as evidenced by the results of hydroxyproline content. In further comparison with commercial sugar beet pectin (SBP), the PSHP exhibited similar emulsifying properties with SBP over the pH range of 2–6. Moreover, the foam ability and stability were even higher than those of SBP, especially at pH 4.0. These findings suggest that PASW‐UT could be used as an effective strategy to prepare novel surface‐active pectin from soya hull.     

Effects of the proteinaceous moiety on the emulsifying properties of sugar beet pectin

The role of the proteinaceous moiety in emulsifying was investigated using pectin from sugar beet as a model polysaccharide. Physicochemical and macromolecular characteristics of sugar beet pectin were examined with or without an enzymatic modification using multiple acid-proteinases. The enzymatic modification decreased the total protein content from 1.56±0.15% to 0.13±0.02% by the Bradford method without significant change in ferulic acid or most constitutional sugars. It also decreased the weight-average molecular weight (M_w) from 517±28 to 254±20 kg/mol and the z-average root-mean-square radius of gyration from 43.6±0.8 to 35.0±0.6 nm. Emulsifying properties of the polysaccharide with or without the enzymatic modification were evaluated by emulsion droplet size and creaming stability of O/W emulsions (pH 3.0) containing 15 w/w% middle-chain triglyceride and 1.5 w/w% sugar beet pectin as main constituents. The modification increased the average diameter (d_3,2) of emulsion droplets from 0.56±0.04 to 3.00±0.25 μm immediately after the preparation, suggesting a decrease in the emulsifying activity. It caused the creaming of the emulsions during incubation at 60 °C, which was in line with the finding that macroscopic phase separation occurred only in the presence of the modified pectin after storage at 20 °C for a day, suggesting a decrease in the emulsion stabilizing ability. The modification also decreased significantly the amount of the pectin fraction that adsorbed onto the surface of emulsion droplets from 14.58±2.21% to 1.22±0.03% and the interfacial concentration of the polysaccharide from 1.42±0.23 to 0.45±0.05 mg/m², where the proteinaceous materials in the pectin molecules activated the oil-water interface. Results from the present study suggest an important role of the proteinaceous moiety to explain the emulsifying properties of sugar beet pectin as in the case of gum arabic and soy soluble polysaccharide.     

炮制法对三叶木通果皮果胶提取及理化性质的影响

为提高三叶木通果皮果胶提取率和质量,探究不同炮制方法对三叶木通果皮果胶提取及其理化性质的影响.以未处理的三叶木通果皮生粉和炒制、砂制、醋制、酒制方法处理的果皮粉为原料,酸法提取得到果胶并进行结构表征,测定其果胶提取率、半乳糖醛酸质量分数、酯化度、乳化活性、乳化稳定性及抗氧化性.结果表明:醋制果胶提取率、半乳糖醛酸质量分...     

超声-酶法提取的豆腐柴低酯果胶理化性质及结构表征

以豆腐柴为原料,采用超声-酶法提取低酯果胶,并探究其理化性质、结构特征、抗氧化活性以及流变特性。结果表明,超声-酶法提取的果胶得率达35.53%,相比传统酸法提取提高17.28%,属于低酯果胶(酯化度为16.80%),颜色呈现淡黄色,其总糖醛酸含量达到81.17%(质量分数)。通过高效液相色谱法对果胶分子质量进行测定,其重均分子质量(M w)为27.24 kDa,数均分子质量(M n)为15.30 kDa,M w/M n为1.78,表明豆腐柴果胶分子质量较低,且较为均一。单糖组成分析发现,半乳糖醛酸、葡萄糖、鼠李糖、半乳糖等是主要组分,其结构线性度较低,主要结构为短侧链的RG-Ⅰ型。红外光谱扫描特征峰证实其含有果胶成分;扫描电镜显示其表面粗糙,含有较多孔隙结构;X射线衍射表明豆腐柴果胶具有一定的结晶度;差示量热扫描、热重分析显示豆腐柴果胶在259.3℃发生降解,热稳定性较好;流变学分析结果表明不同浓度豆腐柴果胶溶液均出现剪切变稀现象,为非牛顿流体,10 g/L的果胶溶液储能模量(G′)高于损耗模量(G″),表现出较好的弹性;抗氧化活性测定显示豆腐柴果胶清除DPPH自由基、ABTS阳离子自由基的IC 50分别为0.37、0.34 g/L。研究结果为豆腐柴低酯果胶的开发及综合利用提供理论依据。     

果胶结构、提取方法及乳化特性研究进展

果胶是一种重要的酸性大分子多糖物质,具有良好的凝胶性、增稠性和乳化特性,被广泛应用于食品加工业中。果胶的结构及乳化特性会受到提取方法的影响,本文综述了果胶的分子结构及不同提取方法的应用特点,并介绍了影响果胶乳化特性的结构因素(蛋白质、阿魏酸、乙酰基、中性糖侧链、分子量)和环境因素(果胶浓度、油相浓度、pH、盐离子)及果胶与蛋白质结合用于稳定乳化液的研究现状,最后对果胶的研发前景进行展望,以期为果胶的开发和应用提供一定的理论参考。