Ca(OH)2对大米淀粉凝胶特性的影响

该研究从大米中提取大米淀粉,向其中添加不同质量分数(0%～1.6%)的Ca(OH)₂,研究大米淀粉的结晶度、热特性、糊化、流变、质构、淀粉短程有序性以及淀粉凝胶中水分状态的变化。结果表明,Ca(OH)₂使大米淀粉的相对结晶度和糊化焓降低,添加量小于0.8%时,冷糊黏度提高、回生性能改善,添加量为0.8%时,冷糊黏度和回升值达到最大值,分别为对照组的1.31倍和3.93倍。Ca(OH)₂可改善大米淀粉凝胶的流变和质构特性,添加量为0.8%时,大米淀粉凝胶的贮能模量、硬度和咀嚼性达到最大值。通过比较傅里叶红外光谱上1 047 cm^-1/1 022 cm^-1和1 022 cm^-1/995 cm^-1比值可知,随着Ca(OH)₂添加量增加,大米淀粉的短程有序性呈先增加后降低的趋势。通过低场核磁共振测定大米淀粉凝胶的横向弛豫时间T₂,发现Ca(OH)₂使自由水的比例显著增加,一部分...     

植物蛋白凝胶特性的研究

首先采用流变仪全面测定凝胶组织结构参数，为研究蛋白凝胶形成四大步骤、影响凝胶品质的因素奠定了基础，并确定：蛋白含量高于９０％分离蛋白，浓度％－２０％，加热温度高于其变性温度下，可制得性能良好的凝胶。     

3种薯类淀粉的流变与凝胶特性研究

对比了马铃薯、红薯和木薯淀粉的糊化、流变及凝胶特性。当浓度从5%增至10%时,3种薯类淀粉的峰值黏度增加2~7倍。马铃薯淀粉糊的触变性最强;在50~95℃范围内,马铃薯淀粉糊的动态黏弹性高于红薯和木薯淀粉糊。马铃薯淀粉凝胶的硬度和胶黏性最高,红薯淀粉凝胶的弹性最大;3种淀粉的凝胶都呈网络结构,网孔大小为20~350μm;马铃薯淀粉凝胶的网孔轮廓最为清晰紧凑。     

大米谷蛋白对大米淀粉凝胶化及凝胶特性的影响

研究大米谷蛋白添加量(0%～14%)对籼米淀粉流变、热特性及淀粉凝胶特性的影响。结果表明,随着大米谷蛋白添加量增加,米淀粉的弹性模量峰值(G'_(peak))、黏性模量峰值(G"_(peak))及淀粉凝胶的硬度均呈升高趋势。谷蛋白对米淀粉的DSC吸热峰的起始温度和峰值温度没有明显的影响,但是混合体系的焓值随谷蛋白添加量增加而降低。随大米谷蛋白添加量增加,米淀粉凝胶的黏聚性、黏性及回弹性均呈升高趋势。扫描电镜显示,添加大米谷蛋白米淀粉凝胶的孔洞深度增加、直径增大,结构显得较为松散。     

大米凝胶特性的研究现状与展望

大米的凝胶特性与大米的化学成分及其制品的加工品质有一定程度的关联。综述了近年来国内外有关大米凝胶特性的研究现状,阐述了大米凝胶特性的影响因素及评价大米凝胶特性的测定方法及其特点。为开发快速、准确、操作方便的凝胶特性测定方法及相关仪器提供了新方法和新思路,为进一步研究大米凝胶特性提供了理论参考。     

麦冬多糖对大米淀粉凝胶化及凝胶特性的影响

为研究麦冬多糖对大米淀粉凝胶化及凝胶特性的影响,分别以0%、2%、4%、6%和8%的麦冬多糖替代大米淀粉,研究麦冬多糖对大米淀粉糊化特性、静态流变、动态流变、凝胶质构及水分子状态的影响。结果表明：麦冬多糖以浓度依赖的方式使大米淀粉糊的峰值黏度等糊化黏度参数均降低,而峰值时间和糊化温度则增加。不同样品均为假塑性流体,幂律方程能够较好地拟合其静态流变行为,假塑性随麦冬多糖添加量增加而增强,稠度指数随麦冬多糖添加量增加而降低。麦冬多糖使大米淀粉糊的黏弹性及凝胶的硬度、内聚性、咀嚼性和回复性均降低。凝胶中的水分子主要呈游离态,结合水和束缚水含量较少,添加麦冬多糖降低了大米淀粉凝胶中水分子的运动性。     

储藏温度对稻米淀粉糊化特性的影响

为研究稻谷储藏温度对稻米淀粉糊化特性的影响,用人工气候箱将早籼稻谷在5、15、25、35 C条件下储藏12个月.分析测定了不同温度储藏稻米淀粉的提取率、色泽、溶解度、润涨力、糊化特性及淀粉凝胶的质构特性.结果表明,相对于新收获稻米,经35℃储藏稻米提取的淀粉色泽微黄,淀粉提取率降低了19.65％;5℃储藏稻米淀粉在90℃时的膨润力最大,经储藏处理稻米淀粉在80℃和90℃的溶解度均高于新收获稻米;稻米淀粉的糊化温度和淀粉凝胶的硬度随储藏温度升高而增加,淀粉的峰值黏度和最终黏度及淀粉凝胶的黏聚性随储藏温度升高而降低.     

7种特色根茎类淀粉的流变与凝胶特性研究

为拓宽中国南方特色根茎类淀粉的应用途径,选取了木薯淀粉为对照,对淮山淀粉和香芋淀粉等根茎类淀粉的糊化、流变和凝胶特性进行了比较研究。结果表明,不同作物间淀粉的流变与凝胶特性差异显著,而不同作物品种间差异相对较小。各淀粉均在69.77～84.37℃时开始糊化,淮山淀粉和香芋淀粉的糊化温度、峰值时间均大于木薯淀粉。木薯淀粉的崩解值高于淮山淀粉和香芋淀粉。7种根茎类淀粉的弹性模量和黏性模量均随频率增加而增加,且损耗角正切值(tanδ)1,表现出典型的弱凝胶动态流变学图谱。香芋淀粉和木薯淀粉的凝胶强度、硬度、胶黏性相近,且显著低于淮山淀粉。木薯淀粉凝胶的弹性、内聚性均大于淮山淀粉和香芋淀粉。     

储藏温度对稻米淀粉糊化特性的影响

为研究稻谷储藏温度对稻米淀粉糊化特性的影响,用人工气候箱将早籼稻谷在5、15、25、35℃条件下储藏12个月。分析测定了不同温度储藏稻米淀粉的提取率、色泽、溶解度、润涨力、糊化特性及淀粉凝胶的质构特性。结果表明,相对于新收获稻米,经35℃储藏稻米提取的淀粉色泽微黄,淀粉提取率降低了19.65%;5℃储藏稻米淀粉在90℃时的膨润力最大,经储藏处理稻米淀粉在80℃和90℃的溶解度均高于新收获稻米;稻米淀粉的糊化温度和淀粉凝胶的硬度随储藏温度升高而增加,淀粉的峰值黏度和最终黏度及淀粉凝胶的黏聚性随储藏温度升高而降低。     

浸泡处理对大米淀粉糊化特性及流变特性的影响

为了研究大米的浸泡处理对大米淀粉性质的影响,本文采用快速粘度分析仪(RVA)及流变仪研究了不同浸泡时间对大米淀粉的糊化特性和流变特性的影响。RVA曲线表明,随着浸泡时间的延长,大米米粉的峰值黏度和崩解值都有显著提高(p<0.05),最终黏度和回生值先上升后下降,糊化温度有所降低。流变实验表明,经过浸泡处理的大米淀粉的屈服应力、剪切应力及表观黏度均高于未经处理的大米淀粉;随着浸泡时间的延长,大米淀粉悬浊液的G'_max、G'_{95 ℃}、G'_{25 ℃}、tanδ_{G'25 ℃}和K'_G都呈现减小趋势,表明浸泡处理可以显著影响大米淀粉凝胶强度,提高其稳定性。     

自然发酵工艺对米粉流变学性质的影响

本文通过对自然发酵米粉的理化性质和流变性的研究,探讨传统自然发酵对米粉感官性质的作用机理。研究发现发酵过程中总淀粉及直链淀粉含量变化不显著,蛋白、脂肪和灰分含量减少,而游离脂肪酸的含量上升。流变学测定发现,发酵法生产的米粉相对于对照样品最大破断应力减小而最大应变增加。快速黏度分析仪(RVA)测定表明发酵样品的RVA粘度减小、糊化温度降低。感官评定结果表明发酵法生产的米粉柔韧筋道,品质更好。     

发芽糙米糊化特性研究

利用热差扫描仪(DSC)对发芽糙米,糙米和白米的糊化特性进行研究,结果表明糙米糊化起始温度(To)、峰值温度(Tp)、终止温度(Tc)最高;碾减率为16.7％白米糊化起始温度(To)、峰值温度(Tp)、终止温度(Tc)最低;发芽糙米糊化起始温度(To)、峰值温度(Tp)高于碾减率为16.7％白米,低于碾减率为8.3％白米。     

Analysis of Genotypic Diversity in the Starch Physicochemical Properties of Nonwaxy Rice: Apparent Amylose Content,Pasting Viscosity and Gel Texture

A total of 499 non‐waxy rice lines including 172 landraces (the landrace set) and 327 cultivars and breeding lines (the breeding line set) were used to study the genetic diversity of starch physicochemical properties, and the differences between the landrace set and the breeding line set were compared. All the rice lines were planted in the same season and at the same location in Hainan province. Wide diversities of starch physicochemical properties were found, e.g. apparent amylose content ranged from 7.9% to 33% in normal rice and up to 39.8% in an amylose extender mutant; peak viscosity ranged from 90.1 to 305.4 RVU, hot paste viscosity from 77.5 to 248.1 RVU, and cold paste viscosity from 111.4 to 412.6 RVU; gel hardness ranged from 9.4 to 61.1 g. The breeding line set had a wider range of physicochemical properties than the landrace set with a rare exception in gel hardness. The mean values of nearly all the parameters showed significant differences between the two sets of rice except for the setback ratio. The adhesiveness and cohesiveness of landrace starches were significantly lower than those of the breeding lines whereas the other parameters of the landrace set were higher than those of the breeding line set. Analysis of correlation among these parameters indicated that most of the traits were significantly correlated. The wide range of physicochemical properties among non‐waxy rice lines allows breeders to obtain breeding lines with desirable grain quality and food processors to select unique rice materials for specialty food processing, in addition to the applications in other processing industries.     

Gelatinization and Pasting Properties of Waxy and Non‐waxy Rice Starches

Gelatinization and pasting properties of diverse rice types grown in two locations were examined by differential scanning calorimetry (DSC) and rotational rheometry, respectively. The data were compared to previously reported molecular starch properties for these samples: specifically, amylose content, starch molecular weight (M_w), and amylopectin side‐chain‐length distributions. Significant correlations were observed between amylose content, starch M_w, and the weight degree of polymerization of the long side chains of amylopectin F₁(DP_w) and many of the gelatinization and pasting properties measured. Higher amylose content corresponded with increased gelatinization onset (T_o) and peak temperatures (T_p), pasting onset and peak temperatures, and decreased peak and trough viscosity. Starch M_w correlated negatively with T_o, T_p, pasting onset, and peak temperature and positively with peak, trough, final, and breakdown viscosity. Amylopectin with DP_w 59‐78 of F₁(DP_w) correlated with increased T_o, T_p, pasting onset and peak temperature, and decreased peak, trough, final and breakdown viscosity. Pasting properties were also somewhat related to DP_w 21 of shorter side chains of amylopectin (F₂(DP_w)). Significant correlations between F₂(DP_w) and peak, final, and breakdown viscosity were observed (r = −0.447*, −0.391*, −0.388*, peak, final, and breakdown viscosity, respectively).     

Physicochemical,Morphological, Thermal and Pasting Properties of Starches Isolated from Rice Cultivars Grown in India

Physicochemical, morphological, thermal, and pasting properties of starches, isolated from basmati (HBC-19 and Bas-370) and non-basmati (Jaya, a coarse cultivar; P-44 and HKR-120, the medium cultivars and Sharbati, fine cultivar) rice cultivars grown in India were studied. The amylose content of starches from different cultivars ranged from 2.25 (Jaya) to 22.21 g/100 g of starch (HBC-19). Jaya, HKR-120, and P-44 cultivars showed soft gel consistency as 84, 73, and 69 mm, respectively, whereas Sharbati, Bas-370 and HBC-19 cultivars showed medium gel consistency as 54, 53, and 58 mm, respectively. Swelling power (at 95°C) indicated a significant positive correlation with amylopectin content (r = 0.828, p < 0.05) and gel consistency (r = 0.983, p < 0.01). Turbidity had a highly significant positive correlation with solubility (r = 0.919, p < 0.01) and amylose content (r = 0.945, p < 0.01). Starch form Jaya cultivar showed the presence of smallest size granules (2.4–5.7 μm) with an average size of 3.96 μm, whereas Bas-370 showed the presence of largest size granules (3.3–6.7 μm) with an average size of 5.0 μm. The transition temperatures, enthalpy of gelatinization (ΔH_gel), peak height index (PHI) and gelatinization range were determined using differential scanning calorimetry (DSC). The starch from Sharbati cultivar showed highest onset temperature (T_o), peak temperature (T_p), conclusion temperature (T_c), enthalpy of gelatinization and peak height index (PHI) of 68.8°C, 73.2°C, 79.0°C, 11.56 J/g and 2.63 respectively. Pasting temperature of rice starches varied from 68.9°C (Jaya) to 74.5°C (Sharbati). The peak viscosities observed were in the range of 2223 to 3297 cP, lowest for HBC-19 starch and highest for Jaya starch.     

分离大豆蛋白凝胶光学性质的研究

深入地研究了分离大豆蛋白凝胶的透明性与ｐＨ值,加热温度、蛋白质浓度、离子强度（ＮａＣｌ浓度）和葡萄糖酸－δ－内酯（ＧＤＬ）的关系。结果表明：在ｐＨ〈３．５或ｐＨ〉５．５,温度〉８０℃、蛋白质浓度〉２．５％、低离子强度（ＮａＣｌ浓度〈１０ｍｏｌ／Ｌ）和无葡萄糖酸－δ－内酯的条件下,有利于形成透明性分离大豆蛋白凝胶。可为进一步研究大豆蛋白凝胶的光学性质和研制透明的大豆蛋白产品提供理论依据。     

小麦淀粉凝胶质构特性研究

为了掌握不同小麦品种淀粉凝胶质构特性;陕西关中小麦品种和西澳面条用小麦品种的淀粉凝胶质构的异同;淀粉的直链淀粉含量、色度及粘度特性与淀粉凝胶质构特性的关系。以参加陕西省关中小麦品种区域试验的15个小麦品种(品系)、西澳8个面条用小麦品种(品系)为材料,研究了小麦品种淀粉凝胶质构特性及淀粉特性与凝胶质构特性的关系。结果表明:不同小麦品种淀粉凝胶质构特性不同,陕西关中小麦品种之间淀粉凝胶质构特性比西澳面条小麦品种之间差异大。直链淀粉含量与凝胶特性无明显关系;色度中L值与凝胶硬度呈显著正相关;粘度特性与淀粉凝胶质构特性显著相关。关中小麦品种小偃6号、小偃128、秦农068和西澳面条小麦品种具有相似的凝胶质构特性。     

鱼糜加工过程中凝胶性能的影响因素研究进展

鱼糜凝胶性能是鱼糜制品品质的一个重要指标,在鱼糜的加工过程中,如何有效提高凝胶强度是目前鱼糜的加工过程中面临的一个焦点问题。本文分析了鱼糜加工过程中影响鱼糜凝胶性能的不同因素,阐述了如何在加工过程中提高鱼糜凝胶强度的方法,提出了鱼糜制品加工应该注意的问题。     

Effect of Degree of Gelatinisation on the Rheology and Rehydration Kinetics of Instant Rice Produced by Freeze Drying

The effect of degree of gelatinisation on the rheology and rehydration kinetics of instant rice produced by freeze-drying was studied. A Rapid Visco Analyser (RVA) was used to analyse the pasting properties of mixtures of ungelatinized and completely gelatinized dried rice starch at varying ratios in order to develop a standard curve between degree of gelatinization and peak viscosity. The degree of gelatinization of instant rice starch prepared by precooking (gelatinization) for varying times was determined using the calibration curve. It was found that 30 minutes or more of precooking produced completely gelatinized rice. The (RVA) pasting profiles for instant rice precooked for varying times showed that the higher the degree of gelatinization, the lower the viscosity peak, and their decrease was proportional to the degree of gelatinisation. The degree of gelatinisation increased with increase in precooking time. A study of rehydration kinetics showed than an increase in pre-gelatinization time increased the rehydration speed. The kinetics data was analysed using the Peleg's model.     

Chemometric Analysis of the Gelatinization and Pasting Properties of Long‐grain Rice Starches in Relation to Fine Structure

Chemometric tests were carried out to better understand the multidimensional facet of starch fine structure‐relationship concerning gelatinization and pasting properties. With Ward's hierarchical cluster analysis 20 long‐grain rice starch samples were sorted out into three clusters based on similarities in functional properties, particularly, paste peak (PV) and final viscosity (FV). The three clusters (arbitrarily named Clusters A, B, and C) exhibited a pasting profile trend of PV<FV, PV˜FV, and PV>FV, respectively. Cluster A samples were also lower in peak temperature, range and enthalpy of gelatinization, and swelling power. These attributes were associated with higher amylose content (AM), β‐amylolysis limit, and percentage of B1 chains (DP13‐24), but lower amylopectin weight‐average molar mass (M_w) and percentage of A chains (DP6‐12). A 5‐variable linear discriminant function correctly predicted 85% of the Ward's cluster membership of the individual cultivars. The discriminant function included the variables A, B1, and B2 (DP25‐36) chains, average chain length (ACL), and gyration radius (R_z). Fine structure variance was fully explained by a total of nine principal components, with the first three components cumulatively accounting for 74%. The leading variables included in the three rotated components pertained to amylopectin chain length distribution (A, B2, and B3+ or DP≥37 chains, and ACL) and amylopectin molar mass (M_w, R_z, and polydispersity). AM and M_w were loaded most frequently in the 4‐variable, best‐fit linear regression models for predicting gelatinization and pasting properties. A combination of at least two fine structure variables controls the functionality of rice starch.