变性对大米淀粉热膨化性质的影响

以醋酸酐、三聚磷酸钠和环氧氯丙烷为变性剂对大米淀粉进行醋酸酯、磷酸酯及交联变性,制得不同取代度的大米变性淀粉。将变性淀粉在已优化的条件下进行热膨化,以膨化率及脆度为指标研究变性对淀粉热膨化性质的影响。结果表明:与原淀粉相比3,种变性淀粉的热膨化性质均得到了改善,但交联变性的改善程度不如酯化变性的好。淀粉醋酸酯的取代度为0.083 1时,膨化率和脆度分别为9.3和0.164 kg.s;淀粉磷酸酯的取代度为0.007 7时,膨化率和脆度分别为9.6和0.166 kg.s;交联淀粉的沉降积为2.4 mL时,膨化率和脆度分别为8.8和0.168 kg.s,原淀粉的膨化率和脆度分别为7.6和0.300 kg.s。试验表明在原淀粉中添加适量的变性淀粉可以显著改善其热膨化性质。     

蔗糖和海藻糖对糯米淀粉黏滞性和热特性的影响

为研究糖种类和糖添加量对糯米淀粉黏滞性和热特性的影响,利用快速黏度分析仪和差示扫描量热仪测定添加不同浓度蔗糖和海藻糖的糯米淀粉的黏度、糊化温度及热焓值的变化。结果表明：2种糖均能使淀粉的糊化温度升高,且蔗糖提高淀粉糊化温度的能力略高于海藻糖。随着蔗糖和海藻糖添加量的增加,淀粉峰值黏度和最终黏度均增加,淀粉糊的热稳定性增强。糖质量分数小于6％时,淀粉热焓值随着糖添加量的增加而增加,糖质量分数大于6％时,随着糖添加量的增加,淀粉热焓值有下降趋势,且蔗糖对淀粉热焓值的影响要明显高于海藻糖。     

Morphological structure and properties of bamboo shell fiber

The morphological structure and properties of a natural bamboo shell fiber are analyzed. The fiber has a slight natural convolution morphological structure with a rough surface, and its cross-section has irregular zigzag shape with a hole in the middle, which shows the typical structure of cellulose fiber. The crystalline degree of the fiber is about 68.2%, which is higher than that of the cotton. The bamboo shell fiber has good moisture absorption and desorption properties, and it begins to degrade at about 345℃, and there is a large mass loss in the range from 410℃ to 470℃.     

竹笋壳提取物抑菌活性研究

以竹笋壳为原料,利用超声波辅助-有机溶剂提取法提取活性物质,并经大孔树脂初步纯化：采用双层平板打孔法研究竹笋壳提取物对食品中常见的4种细菌和3种真菌的抑制作用,同时考察温度和紫外照射对其抑菌活性稳定性的影响。实验结果表明：竹笋壳提取物对金黄色葡萄球菌（Staphyloccocusaureus）、枯草芽孢杆菌（Bacillussubtilis）、蜡状芽孢杆菌（BacillusCeFCUS）、大肠杆菌（Escherichiacoli）这4种细菌的最小抑菌浓度（MIC）分别为8．75、4．375、35、35mg／mL,对酿酒酵母（Saccharomycescerevisiae）、黑曲霉（Aspergillus niger）、根霉（Rhizopus stolonifer）这3种真菌没有抑制作用;竹笋壳提取物的抑菌活性具有很好的热稳定性;对于不同菌种,竹笋壳提取物的抑菌活性具有不同的紫外光稳定性。     

羟丙基糯米淀粉的制备及其性质的研究

以糯米淀粉为原料制备羟丙基淀粉,考察了环氧丙烷用量、反应时间、反应温度、淀粉乳浓度、氢氧化钠、硫酸钠对淀粉取代度和反应效率的影响,并对不同取代度的羟丙基淀粉的性质进行了研究。实验结果表明,以上各因素对羟丙基淀粉的取代度都有明显的影响,而且不同取代度的羟丙基淀粉的透明度和冻融稳定性及表观黏度比原淀粉都有提高,但白度变化不明显。     

交联辛烯基琥珀酸大米淀粉酯的制备及其糊化性能

以大米淀粉为原料,三偏磷酸钠为交联剂,辛烯基琥珀酸酐(OSA)为酯化剂,制备了交联辛烯基琥珀酸大米淀粉酯(CLOSRS)。结果表明,制备CLOSRS的最佳工艺条件为:酯化温度85℃、pH9.5、OSA用量4.0%、酯化时间2.5 h。在最佳工艺条件下,CLOSRS取代度为0.0198。大米淀粉经交联、酯化后,理化性质和糊化性能得到改善。其溶解度由2.73%升至15.88%,透光率由7.57%升至14.73%,冻融稳定性也得到提升;糊化性能中的峰值黏度由2246 cp升至5326 cp,回生值由1276 cp降至273 cp,糊化温度由82.45℃降至76.32℃。      

羧甲基大米淀粉的半干法制备及表征

以大米淀粉和氯乙酸钠为原料,采用半干法制备羧甲基淀粉(CMS)。考察了氯乙酸钠用量、NaOH用量、醚化温度、醚化时间和碱化温度等条件对产物取代度的影响,并对得到的CMS的红外光谱和晶型进行了表征分析。结果表明:半干法合成CMS的单因素优化条件为:nMCA/nAGU=1,nNaOH/nAGU=1.25,碱化温度35℃,碱化时间1h,醚化温度70℃,醚化时间2.5h,在该条件下得到取代度为0.45的产物,其红外光谱在1 300~1 600cm~(-1)处出现了新的吸收峰,为羧基官能团特征峰,其晶型由多晶颗粒结构转变为无定型结构。     

Physicochemical,functional, thermal and structural properties of isolated Kabuli chickpea proteins as affected by processing approaches

Kabuli chickpea seeds were processed by soaking only and soaking followed either by pressure cooking or roasting. Proteins were isolated from both raw and processed seeds, and the effects of these processing approaches on the physicochemical, functional, thermal and structural properties as well as SDS‐PAGE profiles of the protein isolates were investigated. Thermal processes significantly (P < 0.05) decreased protein yield, content, colour difference, emulsifying properties and protein solubility of the protein isolates, but increased lightness and water and oil absorption capacities. Protein thermal properties, secondary structure and SDS‐PAGE banding patterns were significantly changed in thermal‐processed samples, especially those that were pressure cooked. No endothermic peak was detected in differential scanning calorimetry thermograms, and peak intensity of amide I absorption band at 1600–1700 cm^?1 in Fourier transform infrared spectra reduced. The results reveal that pressure cooking had more pronounced effects on the properties of the protein isolates than other processing approaches.     

竹笋壳提取物中有效成分的GC/MS分析研究

为了探讨竹笋壳中生物活性物质的组成成分,利用超声波辅助-有机溶剂提取法提取竹笋壳中的活性物质,并经大孔吸附树脂初步分离纯化。以N,O-双(三甲基硅烷)三氟乙酰胺(BSTFA,含1%的三甲基氯硅烷TMCS)为衍生化试剂,采用气相色谱-质谱联用技术及运用面积归一化法定性定量鉴定竹笋壳提取物中所含有效成分。结合气相色谱-质谱标准谱图库NIST进行人工结构解析确定了15种物质的化学结构,其中常见脂肪酸有11种,酚酸有2种,脂肪酸的相对含量为29.71%,酚酸的相对含量为10.96%。     

大米淀粉磷酸酯的制备及其理化性质研究

为合理地利用丰富的大米淀粉资源,以大米淀粉为原料,尿素为催化剂,正磷酸盐为酯化剂,采用响应曲面法确定了制备大米淀粉磷酸酯的最佳工艺条件:磷酸盐用量为淀粉质量的46.61%,催化剂用量为淀粉质量的4.03%,反应pH为5.5,反应时间为4.6 h。在此条件下制得的磷酸酯淀粉的取代度为0.020 34。并用扫描电镜(SEM)对反应前后淀粉颗粒的形貌进行了观察,结果表明,磷酸酯化后,部分淀粉颗粒受到侵蚀。同时研究了大米淀粉磷酸酯的理化性质,包括溶解度、膨胀度、糊化特性、凝沉性、冻融稳定性及黏弹特性。结果表明,相对于原淀粉,磷酸酯淀粉的溶解度、膨胀度、黏度有所提高,糊化温度、凝沉性、凝胶硬度和强度则下降。     

核桃蛋白对大米淀粉凝胶化及凝胶特性的影响

研究不同核桃蛋白添加量下大米淀粉的糊化特性、流变特性、热特性及凝胶质构和水分子状态.结果表明,核桃蛋白以浓度依赖的方式降低了大米淀粉糊的黏度和相变焓值,而使糊化温度升高,当核桃蛋白添加质量分数达12％时,峰值黏度、谷值黏度、最终黏度分别降低了 30.77％、12.35％和14.65％,糊化温度升高了 8.89％;所有样...     

Morphology and structural properties of high-amylose rice starch residues hydrolysed by amyloglucosidase

High-amylose starches are attracting considerable attention because of their potential health benefits and industrial uses. Enzyme hydrolysis of starch is involved in many biological and industrial processes. In this paper, starches were isolated from high-amylose transgenic rice (TRS) and its wild type rice, Te-qing (TQ). The morphological and structural changes of starch residues following Aspergillus niger amyloglucosidase (AAG) hydrolysis were investigated. AAG hydrolysed TQ starch from the granule surface, and TRS starch from the granule interior. During AAG hydrolysis, the content of amorphous structure increased, the contents of ordered structure and single helix decreased, and gelatinisation enthalpy decreased in TQ and TRS starch residues. The A-type polymorph of TRS C-type starch was hydrolysed faster than the B-type polymorph. The short-range ordered structure and B-type polymorph in the peripheral region of the subgranule and the surrounding band of TRS starch increased the resistance of TRS starch to AAG hydrolysis.     

Influence of wheat starch on rheological,structural and physico-chemical properties gluten–starch dough during mixing

This study mainly explored that the influence of wheat starch source on the rheology behaviours and structural properties of gluten–starch dough, and then the model doughs were prepared by the AK58 wheat gluten and three types of starches from strong (ZM366S), medium (AK58S) and weak gluten wheat (ZM103S) during mixing were studied. The damaged starch content of wheat starch was positively correlated with the wheat gluten strength, while the granule size was negatively. The G', G" and the extension resistance of ZM366S dough were higher than those of other doughs, which implied the source of starch also had a significant influence on the rheological properties. CLSM also observed that ZM366S was more closely bound to the gluten protein network. The glutenin macropolymer (GMP) content of ZM366S model dough was the highest, while the SH content was the lowest. Decreases in elasticity, extension and GMP, and small increase in SH content were displayed during dough mixing. Molecular forces were varied with different wheat starch and mixing time. The covalent bond was the main force between ZM103S and gluten, whereas the hydrogen and covalent bonds were the main force between ZM366S or AK58S and gluten. The interactions between ZM366 starch and gluten were stronger than others starch.     

湿热处理对大米淀粉理化性质及其米线品质的影响

以大米淀粉为原料,研究湿热处理对大米淀粉理化性质以及米线品质的影响。结果表明:与未处理大米淀粉相比,湿热处理后,大米淀粉的热学特性中T_0、T_P、T_C、T_C_T0、ΔH均增大;淀粉晶型仍为A型,结晶度增加4.14%;淀粉溶解率和膨润力显著降低,直链淀粉含量显著升高;淀粉糊化黏度、衰减值和回生值明显降低;淀粉凝胶硬度、弹性和耐咀嚼性增强;淀粉白度由89.7降低至80.3;添加20%湿热处理大米淀粉制作的米线感官品质和质构特性得到显著改善,断条率和蒸煮损失率分别降低5.67%,10.13%;大米淀粉溶解率、膨润力、溶解率、凝胶特性和糊化特性可有效预测米线品质。     

Extrusion improved the physical and chemical properties of dietary fibre from bamboo shoot by-products

Bamboo shoot by-products are regarded as waste and environmental pollutant. This study aimed to improve the functional properties of dietary fibre from bamboo shoot by-products. After CO₂ extrusion, the particle size of CO₂-extruded bamboo fibre was 17.6% lower than that of the control, and its specific surface area was 2.85 times that of the control. The soluble dietary fibre content was significantly increased from 5.64 g/100 g to 11.05 g/100 g (P < 0.05), and the capacities for water holding, swelling and oil holding were remarkably improved. The cholesterol adsorption of CO₂-extruded bamboo fibre was increased from 96.54 μg g⁻¹ to 174.65 μg g⁻¹ (pH 7.0), and its nitrite ion adsorption capacity was increased from 503.33 μg g⁻¹ to 657.27 μg g⁻¹ (pH 2.0). In summary, the structural changes of bamboo fibre such as internal porosity, surface roughening and low crystallinity indicated that its functional properties were improved after CO₂ extrusion.     

粳米分层淀粉的理化性质

目的:提高粳米淀粉的高值化利用和粳米分层淀粉的综合应用。方法:分别采用碱法和酶法提取粳米淀粉,对离心后3层淀粉的基础成分、溶解度、膨润力和糊化特性等理化指标进行分析,并采用扫描电镜、红外光谱分析其结构特性。结果:碱法和酶法提取的各层淀粉的淀粉含量为91%～99%,其中中层淀粉的相对比例最高,碱法和酶法提取的中层淀粉的淀粉含量高于上层和下层,而上层和下层淀粉的蛋白质含量和直链淀粉含量均高于中层淀粉的。碱法和酶法提取的各层淀粉的溶解度和膨润力均随温度的上升而增加,且碱法和酶法提取的上层和下层淀粉的热稳定性优于中层淀粉的。扫描电镜结果显示碱法和酶法提取的各层淀粉颗粒均较为完整,酶法提取的各层淀粉颗粒分布相对稀疏;红外光谱图中,碱法和酶法提取的各层淀粉具有相似的主要特征吸收峰,中层淀粉的短程有序性高于上层和下层淀粉。结论:可进一步开发利用粳米上层和下层淀粉,提高粳米资源的综合利用。     

超高压技术对大米淀粉物性影响初探

以大米淀粉为原料,通过超高压处理成不同颗粒大小的淀粉颗粒,对其进行物理特性的研究。结果表明,超高压处理后的大米淀粉的物理特性会发生意想不到的变化,如溶解度、膨润力、表观粘度和流变性等会随颗粒大小变化而变化。