复合湿热处理对苦荞全粉理化特性及体外消化性的影响

采用湿热处理(HM-T)、湿热复合普鲁兰酶处理(HM-E-T)、湿热复合微波处理(HM-M-T)、湿热复合柠檬酸处理(HM-C-T)4种方法,研究不同湿热处理对苦荞全粉(N-T)理化特性及消化性的影响.结果表明:经处理后苦荞全粉总膳食纤维和直链淀粉含量显著增加(P>0.05),其中HM-E-T效果最显著,HM-C-T次之;差示热量扫描仪检测结果显示,湿热处理后苦荞全粉黏度均显著降低且相变峰消失;X射线衍射结果表明,HM-T淀粉仍为A型结晶,HM-E-T淀粉由A型淀粉转变为A+B+V的多晶型,而HM-M-T和HM-C-T淀粉失去了原有晶形结构,淀粉相对结晶度从23.0％(N-T)下降至20.9％(HM-T)、18.4％(HM-E-T)、12.6％(HM-M-T)和10.6％(HM-C-T);扫描电子显微镜和激光共聚焦电子显微镜观察结果表明,处理后的苦荞全粉微观结构发生不同程度的变化,蛋白质和淀粉发生一定程度复合.体外消化结果显示,苦荞全粉中抗性淀粉质量分数从9.69％(N-T)分别增加到11.49％(HM-T)、14.12％(HM-E-T)、11.97％(HM-M-T)、13.01％(HM-C-T);预估血糖生成指数(eGI)出现不同程度的降低,即57.85(N-T)>56.03(HM-T)>55.65(HM-M-T)>55.18(HM-C-T)>50.22(HM-E-T),特别是HM-E-T后的苦荞全粉eGI值降低效果最明显.复合湿热处理比湿热处理更能有效降低餐后谷物血糖生成指数(GI)值,其中HM-E-T后的苦荞全粉可作为低GI食品的理想原料.     

青稞β-葡聚糖对淀粉体外消化性的影响

对比青稞全粉和普通小麦粉体外消化性,研究青稞β-葡聚糖质量浓度和分子质量对青稞淀粉体外消化性的影响,从青稞β-葡聚糖流变学特性及其与α-淀粉酶的相互作用方面,探究青稞降血糖的可能机理。结果表明,青稞全粉中淀粉消化率明显低于小麦粉;随青稞β-葡聚糖质量浓度和分子质量的增大,其溶液黏弹性增大,对α-淀粉酶活性的抑制效果越明显,延缓淀粉体外消化效果越显著。青稞β-葡聚糖形成的高黏性环境是青稞全粉低淀粉消化率的潜在机理。     

不同糊化度苦荞粉理化性质和体外消化性的研究

以苦荞全粉和芯粉为原料,通过挤压膨化制备不同糊化度(61.27％～97.65％)的苦荞粉样品,对其理化特性及体外消化性进行研究.结果表明:随着糊化度的增大,苦荞粉的水分、脂肪及黄酮含量显著降低(P＜0.05);粒径、吸水性指数、水溶性指数及膨胀度显著增大(P＜0.05);快速黏度分析结果表明高糊化度苦荞粉的峰值黏度、谷...     

马铃薯-小麦粉混粉的理化性质与消化特性研究

以不同比例马铃薯全粉(PG)和小麦粉(WF)混粉为研究对象,探讨了马铃薯全粉与小麦粉混合比例对混粉还原糖、溶解度、膨胀度、冻融稳定性、糊化特性、快消化淀粉含量、慢消化淀粉含量、抗性淀粉含量及消化速率的影响。结果表明,马铃薯全粉具有较低的还原糖含量,较高冻融稳定性、糊化温度、快消化淀粉含量和消化速率。小麦粉的慢消化淀粉和抗性淀粉含量较高,消化速率较低。马铃薯全粉与小麦粉比例为9∶1时,溶解度和膨胀度最高。比例为1∶9时,糊化温度最低。马铃薯全粉和小麦粉的混合比例对混粉的理化性质及消化特性有明显影响。      

过热蒸气处理对苦荞粉理化性质的影响

采用不同温度的过热蒸气对苦荞全粉(苦全)和苦荞芯粉(苦芯)进行改性,考察其对苦荞粉的糊化性质、热力学性质、体外消化能力和苦荞粉多酚含量及抗氧化能力的影响。结果表明,过热蒸气能够显著增加苦荞粉的峰值黏度和谷值黏度并降低其回生值,显著提高苦荞粉的糊化温度和糊化焓值,且其糊化焓值随着处理温度的增加而增加(P<0.05)。过热蒸气处理之后苦荞粉中快速消化淀粉和慢性消化淀粉的含量显著降低(P<0.05),相反抗性淀粉的含量显著增加(P<0.05),但不同温度处理组之间无显著性差异(P>0.05)。另一方面,过热蒸气处理显著增加了苦荞粉中可溶性共轭多酚和结合多酚的含量(P<0.05),显著降低游离多酚和总酚含量(P<0.05)。抗氧化能力变化趋势同多酚含量变化趋势一致。该研究过热蒸气能够明显改变苦荞粉的理化性质,显著降低苦荞粉的体外消化能力,提高其营养价值,为其在健康功能食品的应用提供新的可能。     

不同工艺制备的马铃薯全粉理化性质比较

以同一品种新鲜的马铃薯为原料,比较研究了应用不同工艺制备的马铃薯雪花粉、马铃薯颗粒粉和马铃薯生全粉的理化性质。采用扫描电子显微(SEM)、X-射线衍射(XRD)、快速黏度分析仪(RVA)和色度仪分别对马铃薯全粉的微观形貌、颗粒结构、糊化特性和亮度值进行了表征,并测定了马铃薯全粉的基本组分和碘蓝值,以中筋小麦粉为参照进行了对比分析。结果表明:马铃薯全粉的膳食纤维含量均高于小麦粉,但淀粉、蛋白含量都低于小麦粉;颗粒粉和生全粉的亮度值较高,但均低于小麦粉,雪花粉的亮度值最低,生全粉的黄值最大;马铃薯全粉中雪花粉的碘蓝值较小、糊化度较大,生全粉的碘蓝值较高,糊化度较低;生全粉中马铃薯淀粉颗粒清晰可见,雪花粉和颗粒粉未能观察到淀粉颗粒;生全粉的衍射峰尖锐,结晶结构完好,雪花粉和颗粒粉的结晶结构被破坏。     

热处理对谷物粉物化性质及淀粉体外消化性的影响

为了研究热处理对谷物粉物化性质和淀粉体外消化性的影响,测定燕麦、小米和玉米3种谷物粉经蒸汽和烘烤热处理前、后糊化特性、膨胀势、吸水性和不同淀粉组成含量的变化。结果表明:热处理使燕麦粉的糊化温度显著降低、小米粉和玉米粉显著升高(P<0.05),燕麦粉和小米粉的回生值显著升高、玉米粉显著降低(P<0.05),玉米粉峰值黏度和崩解值显著降低(P<0.05)、燕麦粉和小米粉的变化不同;蒸汽和烘烤处理使燕麦粉膨胀势分别降低32%和12%,吸水性指数升高20%以上,但是小米粉和玉米粉变化较小;热处理使3种谷物粉水溶性指数降低28%～55%;热处理使3种谷物粉中快消化淀粉含量降低10%～20%,慢消化淀粉含量升高3%～30%,抗性淀粉含量升高20%,尤其热处理对燕麦淀粉组成含量影响最大。扫描电镜观察燕麦、小米和玉米淀粉颗粒直径分别为5,10,15μm,经热处理后淀粉发生团聚和黏结现象,尤其燕麦淀粉团聚和黏结程度最大。结论:适当的预热处理可以改变谷物粉的物化特性,进而改善其加工性能。热处理改变了谷物淀粉的构成,减缓了淀粉的消化性,提高了其功能特性。     

不同品种大米中蛋白质和脂肪对淀粉物化特性影响的研究

以湖北省9个品种的大米作为研究对象,通过对不同品种的大米全粉、脱脂米粉和脱蛋白米粉的物化特性进行比较,研究大米中蛋白质和脂肪对大米淀粉物化特性的影响。结果表明:不同品种大米中的基本物质含量有显著差异(P0.05);脱脂、脱蛋白对大米粉的透光率有较明显的影响;脂肪和蛋白质在大米中抑制了淀粉凝沉的进行,脂肪的抑制效果更明显;蛋白质对大米淀粉的膨润力、溶解度有抑制作用,脂肪对膨润力、溶解度也有小幅度的抑制作用,但没有蛋白质的作用明显;蛋白质对大米淀粉热特性的影响较大,与糊化焓变值呈负相关关系,脂肪对大米淀粉热特性影响较小,与糊化焓变值呈正相关关系;蛋白质阻碍了大米淀粉回生的过程,而脂肪对大米淀粉回生的过程没有影响;不同来源的大米脱脂、脱蛋白处理对淀粉物化特性的影响程度存在差异。     

产糖化酶K-1根霉曲在不同酿酒原料上的应用

研究了K-1根霉曲对不同酿酒原料的水解糖化能力。结果表明,根霉糖化酶对玉米粉、高粱粉、小麦粉、小米粉和苦荞粉的分解率在60 min时都达到了50%左右,均显著高于其他对照酶样品,特别是对小麦粉和苦荞粉的分解能力更是极显著高于其他酶样品;此外根霉糖化酶对黄豆粉也有一定的分解能力。经薄层分析发现,根霉糖化酶将酿酒原料中的淀粉分解为葡萄糖和麦芽糖两大产物。     

萌发苦荞淀粉的理化特性及消化性研究

本试验以萌发苦荞为研究对象,对苦荞萌发过程中淀粉的组成,尤其是淀粉颗粒形态的变化规律以及消化特性进行了研究。试验结果表明:经萌发处理后苦荞淀粉组成发生了变化,其中总淀粉质量分数下降了28.35%,随着直链淀粉的增加,直链淀粉与支链淀粉的比例也随之增大,在第3d时达到0.63;萌发苦荞淀粉的组成也发生变化,其中慢消化淀粉含量明显提高(P0.05);同时,适度萌发仅对淀粉颗粒的无定形区晶体结构产生影响,结晶度随着萌发时间增加逐渐增大,形成部分小分子聚合体。体外消化试验表明:较萌发前,苦荞淀粉消化性能明显改善。从萌发苦荞淀粉颗粒结构与体外消化性相关性分析结果可以看出体外消化率即血糖指数与萌发苦荞淀粉平均粒径呈显著正相关,与其结晶度呈显著负相关。从而揭示了萌发后苦荞淀粉粒径变小,结晶度变大,有利于血糖指数的降低。萌发苦荞淀粉血糖指数(GI)均小于55,属于低GI食品,是目前国内外营养与食品界推荐糖尿病人群理想食物。     

Effects of germination on the physicochemical,nutritional and in vitro digestion characteristics of flours from waxy and nonwaxy proso millet,common buckwheat and pea

Germination can increase the nutritional quality of flours and change their physicochemical properties. In the present study, waxy and nonwaxy proso millet, common buckwheat and pea were germinated for different duration of time (i.e. 0, 1, 2, 3 and 4 d). Subsequent changes in their nutritional, physicochemical and in vitro digestion characteristics induced by germination were assessed and compared. Overall, germination significantly decreased amylose and starch contents and increased the α-amylase activity and contents of crude fibre, soluble sugars, free amino acids and bioactive components of the flours, revealing this physically efficient treatment for improving the nutritional richness of flours. Germination also affected the physicochemical properties and in vitro starch digestibility of these four flours, though it had different effects on their protein digestibility. These findings inform the application of germination in generating nutritionally rich flours with altered physicochemical properties.     

Physicochemical,antioxidant properties and in vitro digestibility of wheat–purple rice flour mixtures

The physicochemical characteristics, antioxidant properties and in vitro digestibility of high‐antioxidant content flours made from different combinations of Thai purple rice flour and refined wheat flour from 25%, 50% to 75% (w/w) were investigated and these were compared with whole flour from purple rice and refined wheat flour. The increase in substitution levels of purple rice flour affected all the functional properties of flours, at the same time the levels of dietary fibre, protein digestibility and antioxidant compositions were also changed. The purple rice flour exerted a particularly strong effect on starch digestibility as the purple rice increased to 50% in the mixture. Moreover, purple rice flour showed lower amounts of rapidly digested starch (RDS), whereas slowly digested starch (SDS) of whole flour from purple rice and 75% substitution purple rice flour was found to be the highest for all samples. The in vitro starch digestibility of all samples also showed a positive correlation between dietary fibre and antioxidant compounds. Overall, the addition of purple rice flour improved the final nutritional properties, notably a lower predicted glycaemic index, and a higher antioxidant potential, which are two important nutritional properties for human health.     

Physicochemical properties,resistant starch content and enzymatic digestibility of unripe banana,edible canna,taro flours and their rice noodle products

Unripe banana, edible canna and taro flours, which have been reported to contain significant amounts of fibre, were investigated for their physicochemical properties, resistant starch (RS) content and in vitro starch digestibility, and compared with commercial high‐fibre‐modified starches from corn and tapioca. Differential scanning calorimetry showed a single endothermic peak located around 70–83 °C for the samples except the modified starches, which exhibited no transition enthalpy. The samples showed different pasting behaviours in the Rapid Visco‐Analyser (RVA) ranging from full to restricted swelling. The RS content varied from 1–26 g per 100 g dry sample, and the estimated glycaemic indices (GIs) of the samples were from 67% to 99%. Generally, samples with high RS were low in GI values. The starches produced acceptable rice noodles but with reduced rate of starch digestion and GI. The effects of the unripe banana, edible canna and taro flours on starch digestibility were either comparable or better than the commercial modified starches. These flours can substitute commercial modified starches to lower GIs of noodles and identical foods.     

预酶解-挤压膨化对全谷物糙米粉品质特性的影响

以3 种糙米（普通糙米、红色糙米、黑色糙米）为原料,预酶解-挤压膨化制备实验组糙米粉,未经预酶解处理直接挤压膨化制备对照组糙米粉,分别测定其水溶性指数、吸水性指数、结块率、分散时间、米糊黏度、色度、糊化度、感官评分以及淀粉、还原糖、蛋白质含量等指标,并对淀粉和蛋白质进行体外模拟消化,比较并分析预酶解-挤压膨化对糙米粉品质特性的影响。结果表明：与直接挤压膨化相比,预酶解-挤压膨化处理使普通糙米、红色糙米、黑色糙米3 种糙米粉的水溶性指数分别提高了2.04、1.35 倍和1.71 倍;吸水性指数分别降低了67.87%、60.96%和62.17%;结块率分别提高了5.44、6.27 倍和3.07 倍;分散时间分别缩短了66.61%、61.79%和64.30%;米糊黏度降低,黏度曲线趋于平直,剪切稀释效应减弱;淀粉含量分别降低了29.22%、28.71%和26.70%,糊化度分别降低了19.53%、8.94%和13.13%;可溶性蛋白含量分别提高了1.50、2.87 倍和2.27 倍;差异均达显著水平（P＜0.05）。同时,亮度值略有升高,色差值分别为3.01、4.66、3.28;快消化淀粉比例降低,慢消化淀粉和抗性淀粉比例升高;蛋白质体外消化速率加快,消化率升高;综合感官评分显著升高（P＜0.05）。实验结果表明预酶解-挤压膨化处理提高了糙米粉的冲调分散性、降低了米糊黏度,提高了感官评分和蛋白质体外消化性能,对糙米粉品质具有提升作用。为拓宽糙米的加工利用途径、促进预酶解-挤压膨化技术在谷物加工领域中的应用提供了理论指导。     

Characteristics of acetylated and enzyme-modified potato and sweet potato flours

The properties of modified potato and sweet potato flours have been determined by incorporating acetyl groups (acetylation) and by treating with glucoamylase (enzymatic modification). Fractionation studies on Sepharose CL-2B showed that the content of high molecular weight fraction decreased, with a proportionate increase in the lower molecular weight carbohydrate fraction, whereas FT-IR indicated changes in crystallinity of the modified starches. The data showed that the degradation of starch is dependent on the type of modification which, in turn, determined its crystallinity and digestibility. The swelling power and solubility patterns of modified flours indicated a greater degree of associative forces in the starch granules. Scanning electron microscopy revealed indentation on acetylated starch granules, and the granules appeared as bunches/clusters, whereas surface erosion was observed in the enzyme-treated samples. The presence of substituent groups in acetylated flour influenced digestibility inversely, whereas improved digestibility was observed in enzyme-modified samples.     

Milk lipid in vitro digestibility in wheat,corn and rice starch hydrogels

Starch-based hydrogels or nanoemulsions have been used to regulate lipid digestibility. However, there is a paucity of reports on how starch gels affect milk lipid in vitro digestion. This study compared the pancreatic-lipase-catalysed digestibility of milk lipids in two matrices: milk fat dispersion and milk fat-loaded starch gels. Optical microscopy analysis illustrated that lipid droplets were distributed evenly in starch gels. The peak viscosities of lipid-containing starch gels were higher than those of samples without filled-lipids, whereas final viscosities were reduced with the addition of lipid. Free fatty acid release measurement showed that milk fat embedded in starch gels were two to three times more digestible than dispersed milk fat globules in aqueous phase, as confirmed by a multistep hydrolysis reaction model. This study offers a feasible way to manipulate milk lipid digestibility by stabilisation with starch gels.     

Effect of different chemical modification on the physicochemical properties of fiber-enriched polysaccharides isolated from wholegrain rice and buckwheat

Dietary fiber (DF) isolated from wholegrain flours (brown rice and buckwheat) were chemically modified by cross-linking (CL), carboxymethylation (CM) and hydroxypropylation (HP). The modified DF was evaluated for its physicochemical characteristics based on compositions, hydration properties and interactions of wheat starch/DF system. The changes in total dietary fiber (TDF) content of were found to be chemical modification-dependent. CM contributed to the increase in soluble dietary fiber (SDF) contents and water solubility. On the contrary, CL and HP significantly increased the insoluble dietary fiber (IDF) contents, resulted in reduced water solubility. Hydration properties of both native and modified buckwheat DF were higher than all rice DF counterparts. In the interaction with wheat starch, starch hydrolysis was low in samples with high TDF contents (CL≈HP>CM≈ native). It was concluded that characteristics of modified cereal DF depended on the presence of functional groups rather than sources of wholegrain.     

冰湖野米粉及其淀粉的精细结构、理化和消化特性研究

目的 探究冰湖野米粉及其淀粉的理化性质、结构特性和消化性的差异, 同时揭示不同级的冰湖野米淀粉的精细结构。方法 以3种不同级的冰湖野米和1种早籼米(对照组)为原料, 将其研磨过筛制备米粉样品, 再用焦亚硫酸钠法和甲苯法进行纯化得到对应的淀粉样品。采用体积排阻色谱分析法(Size exclusion chromatography, SEC)与荧光辅助毛细管电泳法(Fluorescence assisted capillary electrophoresis, FACE)测定冰湖野米淀粉的精细结构(直链淀粉和支链淀粉的链长分布); 利用扫描电镜、光学显微镜、X-射线衍射仪、傅里叶变换红外光谱仪和布拉班徳粘度仪等现代分析仪器对冰湖野米粉及其淀粉的理化性质和结构特性进行测定; 采用Englyst体外消化法测定冰湖野米粉及其淀粉的体外消化性。结果 研究表明, 不同级的冰湖野米粉及其淀粉的颗粒形貌特征、粘度特性、结晶结构以及直链淀粉含量无显著差异。与早籼米相比, 冰湖野米粉及其淀粉的起糊温度高, 峰值粘度低, 相对结晶度低, 热稳定性好, 慢消化淀粉和抗性淀粉含量高, 主要归因于冰湖野米的支链淀粉结构及其较高的直链淀粉含量。与冰湖野米淀粉相比, 冰湖野米粉颗粒更大, 结晶度降低, 膨胀度降低, 慢消化性增加, 主要归因于冰湖野米粉中较高的内源蛋白和纤维含量。结论 冰湖野米中的内源纤维、蛋白质、直链及支链淀粉含量对冰湖野米的粘度特性、膨胀度、结构特性以及消化性有显著的影响。     

In vitro potential of flavonoids from tartary buckwheat on antioxidants activity and starch digestibility

The effects of various flavonoids of Tartary buckwheat (rutin-enhanced flavonoid extract [REFE and quercetin-enhanced flavonoid extract [QEFE]) and individual flavonoids (rutin, quercetin and kaempferol) on the antioxidant activity, inhibition of α-glucosidases and α-amylase and starch digestibility were evaluated. Quercetin possessed the highest antioxidant activity and inhibition of α-glucosidases and α-amylase activity followed by kaempferol and rutin. REFE and QEFE have similar antioxidant and inhibition of α-amylase activities, but QEFE has much higher α-glucosidases inhibition than REFE. Tartary buckwheat flour has the lowest content of rapidly digestible starch and predicted glycaemic index (pGI) compared to maize flour, wheat flour and rice flour. Addition of rutin and quercetin to wheat flour showed a weak or no effect on digestion inhibition, but they inhibited starch digestion under solid complex conditions. Our results may help explain the benefits of supplementing the diet with food rich in flavonoids.