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1.
Ilankovan Paraman N. S. Hettiarachchy Christian Schaefer Markus I. Beck 《Cereal Chemistry》2007,84(4):343-349
Rice endosperm protein was modified to enhance solubility and emulsifying properties by controlled enzymatic hydrolysis. The optimum degree of hydrolysis (DH) was determined for acid, neutral, and alkaline type proteases. Solubility and emulsifying properties of the hydrolysates were compared and correlated with DH and surface hydrophobicity. DH was positively associated with solubility of resulting protein hydrolysate regardless of the hydrolyzing enzyme, but enzyme specificity and DH interactively determined the emulsifying properties of the protein hydrolysate. The optimum DH was 6–10% for good emulsifying properties of rice protein, depending on enzyme specificity. High hydrophobic and sulfhydryl disulfide (SH-SS) interactions contributed to protein insolubility even at high DH. The exposure of buried hydrophobic regions of protein that accompanied high-temperature enzyme inactivation promoted aggregation and cross-linking of partially hydrolyzed proteins, thus decreasing the solubility and emulsifying properties of the resulting hydrolysate. Due to the highly insoluble nature of rice protein, surface hydrophobicity was not a reliable indicator for predicting protein solubility and emulsifying properties. Solubility and molecular flexibility are the essential factors in achieving good emulsifying properties of rice endosperm protein isolates. 相似文献
2.
In vitro protein digestibility (IVPD) of lentils, chickpeas, peas, and soybeans treated with ultrasound or high hydrostatic pressure (HHP) during soaking and then heated for 30 min at 98°C was determined using the three-enzyme method (trypsin, chymotrypsin, and peptidase). The IVPD of raw legumes ranged from 72% for soybeans to 83% for dry green peas. The increase in the IVPD after soaking was observed in lentils but not in other legumes. Heating increased the IVPD of the tested legumes by 2–13%. While the effects of applying ultrasound or HHP on IVPD of legumes were mostly inconsistent or insignificant, soaking under HHP for 1 hr and subsequent heating at 98°C for 30 min increased IVPD of legumes. Compared with raw legumes, the soluble protein concentrates exhibited 2–4% higher IVPD, while insoluble proteins exhibited 0.2–1.5% lower IVPD. SDS-PAGE of legume proteins before enzyme digestion exhibited 8–18 protein bands from 20 kDa to 100 kDa representing isolated soluble proteins and from 20 kDa to 100 kDa representing insoluble proteins. After enzyme digestion, soluble proteins exhibited 2–6 minor protein bands with molecular weights <30 kDa, while insoluble proteins of lentils, chickpeas, and peas exhibited one major protein band at ≈52 kDa and two or three minor protein bands with molecular weights <30 kDa. The major insoluble proteins observed as electrophoresis bands after enzyme digestion may be responsible for the reduced protein digestibility of legume proteins. 相似文献
3.
The enzyme transglutaminase (TG) is known to have beneficial effects on breadmaking. However, only limited information is available on the structural changes of gluten proteins caused by TG treatment. The effect of TG has, therefore, been systematically studied by means of model peptides, suspensions of wheat flours and doughs. The treatment of synthetic peptides mimicking amino acid sequences of HMW subunits of glutenin with TG results in isopeptide bonds between glutamine and lysine residues. To study the effect on gluten proteins, different amounts of TG (0 to 900 mg enzyme protein per kg) were dissolved in a buffer and added to wheat flour. The flour suspensions were incubated and centrifuged and the residues were successively extracted with water, a salt solution, 60% aqueous ethanol (gliadin fraction) and SDS solution including a reducing agent (glutenin fraction). The characterization of the fractions by amino acid analysis, SDS‐PAGE, gel permeation HPLC and reversed‐phase HPLC has indicated that the quantity of extractable gliadins decreases by increasing TG amounts. Among gliadins, the ω5‐type was affected to the greatest extent by the reduction of extractability, followed by the ω1,2‐, α‐ and γ‐types. The oligomeric portion of the gliadin fractions (HMW gliadin) was strongly reduced when flour was treated with 450 and 900 mg TG per kg of flour, respectively. In the first instance, the quantity of the glutenin fractions increased by the treatment of flour with 90 and 450 mg TG per kg of flour, and significantly decreased by the treatment of flour with 900 mg TG per kg of flour. Parallel to an increase in TG concentration, the amounts of glutenin‐bound ω‐gliadins and HMW subunits were strongly reduced, whereas the LMW subunits reached a maximal amount after treatment with 450 mg TG per kg of flour. The insoluble residue was almost free of protein when flour was treated with lower amounts of TG. Higher amounts led to a great increase of protein in the residues. The effects of TG on doughs were similar to those of flour suspensions, but less strongly pronounced probably due to the lower water content of the dough system. Sequence analysis of peptides from a thermolytic digest of the insoluble residue revealed that HMW subunits of glutenin and α‐gliadins were predominantly involved in cross‐links formed by TG treatment. 相似文献
4.
J. S. Hamada 《Cereal Chemistry》1997,74(5):662-668
Proteins from the defatted brans of representative rice cultivars were fractionated into albumins, globulins, prolamins, and acid-soluble glutelins, accounting for 34, 15, 6, and 11% of the total bran proteins, respectively. The remaining insoluble residue protein, after treatment with 0.1M sodium hydroxide, resulted in the solubilization of 95% of the residue protein, representing 32% of the total bran protein. The relative molecular mass (Mr) values determined by size-exclusion HPLC were 10–100 kDa, 10–150 kDa, 33–150 kDa, and 25–100 kDa for the fully dissociated polypeptides of albumins, globulins, prolamins, and acid-soluble glutelins, respectively. Despite a breakdown of disulfide bonds of the residue protein during sodium hydroxide solubilization, the Mr of the majority of the fully dissociated polypeptides of this fraction ranged from 45 to 150 kDa. Insolubility of residue protein was due mainly to its strong aggregation and extensive disulfide bond cross-linking. Efficient methods may be developed for solubilizing up to 98% of rice bran protein by the use of dissociating and disulfide breaking agents currently in use in the food industry. 相似文献
5.
在南方稻区通过大田试验研究不溶性钾矿产品—颗粒硅钙钾肥和多元素微孔矿物肥部分替代氯化钾对晚稻产量、经济效益以及对钾素吸收利用的影响。结果表明:施钾使晚稻增产200.4~577.4 kg/hm~2,40%颗粒硅钙钾肥替代氯化钾增产122.8 kg/hm~2,其他不溶性钾矿产品(颗粒硅钙钾肥、微孔矿物肥)替代氯化钾处理使晚稻减产191.5~254.2 kg/hm~2。施氯化钾和40%颗粒硅钙钾肥使晚稻增收574.7和465.7元/hm~2,不溶性钾矿产品部分替代氯化钾均降低晚稻产投比。施钾处理均能够提高晚稻累积吸钾量和吸钾总量。不溶性钾矿产品部分替代氯化钾对晚稻累积吸钾量和吸钾总量效果不明显,对晚稻钾素利用率的提高没有明显效果。南方稻区晚稻生产中不溶性钾矿产品可以部分替代氯化钾,但不能给当季晚稻生产带来良好的经济效益。 相似文献
6.
为探究抽穗扬花期低温胁迫对不同晚稻品种生理特性的影响,本研究以2个耐冷品种(岳优27、昌粳225)和2个冷敏感品种(泰丰优208、黄华占)为试验材料,于抽穗扬花期在人工气候室进行低温处理,分析其光合特性、抗氧化酶活性、穗部性状与稻米品质等。结果表明,随着低温处理时间的延长,各晚稻品种花粉活力均降低,除过氧化氢酶(CAT)外的抗氧化酶活性、丙二醛(MDA)及可溶性蛋白(SP)含量都有不同程度的增加,其中超氧化物歧化酶(SOD)活性和SP含量呈先增加后降低的趋势,而CAT活性呈先降低后增加的趋势,结实率和千粒重呈降低趋势。低温胁迫也会影响稻米品质及稻米RVA值,具体表现为随着低温处理时间的延长,各晚稻品种精米率降低,垩白粒率、垩白度和胶稠度增加,直链淀粉与粗蛋白含量呈先增加后降低的趋势;峰值黏度、崩解值逐渐降低,冷胶黏度、回复值和消减值逐渐升高。相较于冷敏感品种泰丰优208和黄华占,耐冷品种岳优27和昌粳225的抗氧化酶活性和SP含量较高,MDA含量较低;结实率和千粒重降低幅度较小,花粉活性降低幅度也较小,其中在第5天昌粳225降幅最小,为4.38%;稻米品质中精米率、垩白粒率、胶稠度、直链淀粉含量和蛋白质含量变化幅度较小,而垩白度增加幅度较大,RVA谱中峰值黏度降低幅度较大,热浆黏度反应较慢,而冷胶黏度和回复值较先达到最大值,崩解值和消解值的变化幅度较小。综上,耐冷品种岳优27和昌粳225抽穗扬花期相较于冷敏感品种泰丰优208和黄华占表现出较强耐受低温胁迫的能力。本研究结果可为抽穗扬花期耐低温双季晚稻的选育与栽培提供一定的理论参考。 相似文献
7.
Different protein aggregates including beta-lactoglobulin (beta lg) were detected in the pH 4.6 insoluble fraction recovered from actual heat-treated milk samples by gel electrophoresis and immunoblotting. A competitive enzyme-linked immunosorbent assay (ELISA) using anti-beta lg polyclonal antibodies was developed to analyze the beta lg partition in the protein fractions obtained upon acidification of both milk and Mozzarella cheese at pH 4.6. According to ELISA determinations, nearly 90% of the pH 4.6 soluble beta lg included in raw milk was found in the pH 4.6 insoluble fraction of ultrahigh temperature (UHT)-treated milk. As concerns Mozzarella cheese analysis, ELISA results indicated that about 36% of the total beta lg milk content was transferred from pasteurized milk to Mozzarella cheese, whereas less than 0.5% was transferred from raw milk. The pH 4.6 insoluble beta lg proved to be a suitable indicator of the intensity of the heat treatment applied to milk. The ELISA-based detection of this parameter was suggested for quality control of both drinking milk and raw milk cheese. 相似文献
8.
为了消减冷浸型中低产田长期浸渍、泥温低、土壤有效养分低等障碍因子,通过田间小区试验和动态取样与室内测定,研究了不同有机无机肥配比对冷浸田土壤肥力及水稻生长的影响。结果表明:与复合肥处理比较,复合肥与40%(N)生鸡粪配施处理的土壤磷酸铁盐和磷酸钙盐含量分别提高11%和17%,复合肥与60%(N)生鸡粪配施处理的土壤磷酸铝盐含量提高44%,且磷酸铝盐、磷酸铁盐和磷酸钙盐占无机磷总量的比例提高,闭蓄态磷占无机磷总量的比例降低,促使土壤中难溶性磷向易溶性磷转化,提高土壤有效磷含量;复合肥配施60%(N)生鸡粪处理的土壤松结态腐殖质占重组腐殖质的比例提高1.9个百分点,紧结态腐殖质占重组腐殖质的比例降低4.6个百分点,土壤活性有机质含量提高14%,土壤阳离子交换量提高11%;复合肥与40%(N)生鸡粪配施处理的土壤真菌和放线菌数量分别提高33%和28%,复合肥配施60%(N)生鸡粪处理的土壤细菌数和微生物活性分别提高160%和19%,水稻磷、钾吸收量分别提高5%和111%;复合肥与40%(N)生鸡粪配施处理的早、晚稻产量分别增加8%和42%,复合肥与60%(N)生鸡粪配施处理的早、晚稻产量分别增加6%和31%。有机无机平衡施肥是适合于冷浸田水稻增产的施肥方式。 相似文献
9.
用1×10~5、3×10~5、5×10~5和10×10~5 Gy的电子束和电子束加4％NaOH复合预处理稻麦秸秆。预处理稻秆200目以上粉末随辐照剂量的增加而增中。用1％纤维素酶水解电子束预处理稻麦秸秆48小时,葡萄糖得率随辐照剂量的增加而增加,10×10~5 Gy照射的比未预处理的增加了70％—80％;而复合预处理稻麦秸秆的葡萄糖得率在5×10~5 Gy以内,随辐射剂量增加而增加,分别为36％和35％,比未处理的10.2％增加了约2.5倍,而用10×10~5 Gy的反而下降。通过辐射聚合在纱布表面覆盖高分子poly(HEA)、poly(HEMA)、poly(HPMA)、poly(A-4G)和poly(A-TMPT),并以此作为固定化里氏木霉细胞的载体。这些载体均能较好地固定化里氏木霉细胞,固定化细胞的滤纸活性(FPA)均高于游离细胞,其中覆盖poly(HPMA)的载体固定化细胞的效果最好,FPA为3.5U/ml,比游离细胞增加了近40％。用这些固定化细胞的酶液水解NaOH和电子束复合预处理的稻麦秸秆,其葡萄糖得率随辐照剂量和水解时间的增加而增加,其中4％NaOH和10×10~5 Gy处理的稻麦秸秆第6天的葡萄糖得率为19％和22％。 相似文献
10.
施肥结构对冷浸田土壤肥力及水稻生长的影响 总被引：3，自引：0，他引：3
冷浸田因长期受冷泉水浸渍,土体封闭,难以通气与氧化,土壤溶液Eh下降,有效养分低,水稻产量低。本研究通过田间小区试验和动态取样与室内测定,探求了单质化肥、稳定性肥、复合肥配施生鸡粪和熟鸡粪等施肥方式对冷浸田土壤肥力及水稻生长的影响。结果表明:与单质化肥处理比较,复合肥与熟鸡粪配施处理土壤松结态腐殖质占重组腐殖质的比例提高10.8%,紧结态腐殖质占重组腐殖质的比例降低15.5%,土壤有机质和活性有机质含量分别提高8.9%和4.0%,土壤阳离子交换量提高10.2%,早稻土壤细菌数和微生物活性分别提高390.0%和13.0%;同时土壤磷酸铝盐和磷酸钙盐含量分别提高40.0%和28.0%,且磷酸铝盐和磷酸钙盐占无机磷总量的比例提高,闭蓄态磷占无机磷总量的比例降低,促使土壤中难溶性磷向易溶性磷转化,提高土壤有效磷含量;最终早稻磷、钾吸收量分别提高14.0%和127.0%,早、晚稻产量分别增加11.0%和8.0%。由此得出,有机无机平衡施肥是适合于冷浸田土壤培肥、水稻增产的施肥方式。 相似文献
11.
Piebiep Goufo Luis M. M. Ferreira Corina Carranca Eduardo A. S. Rosa Henrique Trindade 《Cereal Chemistry》2014,91(3):293-299
Little is known regarding the impact of elevated carbon dioxide concentration ([CO2]) on the chemical composition of rice grains. A field experiment was conducted with open‐top chambers with rice (Oryza sativa L. cv. Ariete) grown at two levels of atmospheric CO2 (375 and 550 μmol/mol), and their effects were monitored on the proximate composition and carbohydrate contents of the grains. Following exposure to elevated [CO2], soluble dietary fiber increased by 136, 82, and 77% in brown rice, white rice, and bran, respectively. Increases of a lower magnitude (8%) were observed for insoluble dietary fiber in the bran and brown rice. For all 10 sugars identified, there was a trend for increasing their content. For example, increases of 135% were recorded for glucose in the white rice. In all rice milling fractions, elevated [CO2] reduced the protein (4–15%) and amylose (6–16%) contents, with no effect on the ash, starch, and gross energy contents. The fat content was increased by elevated [CO2] in the white rice (23%) and tended to decrease in the bran (9%). It is concluded that besides yield, increased dietary fiber might be another positive effect of high levels of atmospheric CO2 expected by the middle of the current century. 相似文献
12.
不同水稻品种对难溶性磷利用能力的初步研究 总被引：9，自引：0，他引：9
采用子母盆栽水平分根试验,研究了水稻耐低磷品种莲塘早3号和低磷敏感品种新三百粒对Fe-P、Al-P、Ca-P3种难溶性磷的利用能力。结果表明,与母盆营养液中含正常磷的处理相比,子盆和母盆均不含磷的处理两品种的生物量、根系氧化力下降、MDA含量上升,以难溶性磷为唯一磷源加入子盆石英砂的处理其变化幅度更小,磷含量也比完全缺磷的明显要高,说明根系对难溶性磷的主动活化在起作用;耐低磷品种较高的生物量、磷含量和根系氧化力以及较低的MDA含量表明其活化利用难溶性磷的能力比低磷敏感品种强;不同难溶性磷处理间,各指标的差异与不同形态难溶性磷对水稻有效性的差异有关。另外,缺磷或低磷条件下根冠比增加;磷的有效性越低,其根冠比越高。 相似文献
13.
耕作模式对冷浸田水稻产量和土壤特性的影响 总被引：4，自引：0，他引：4
为探明不同耕作模式对冷浸田的影响机制,挖掘冷浸田的生产潜力,以冷浸田为研究对象,通过田间试验,以常规平作模式为对照,研究了垄作和稻鱼共作模式对冷浸田水稻产量以及土壤团聚体、温度、pH及有机质和还原性物质含量以及酶活性的影响。结果表明:相比对照(CK),垄作模式(T1)能显著降低土壤微团聚体(0.25 mm)含量,促进大团聚体的形成,提高土壤温度,增加土壤有机质含量,提高土壤pH,抑制水稻分蘖期后土壤亚铁含量的上升,降低土壤亚锰含量,减轻其对水稻根系的毒害作用,提高土壤酶活性,增加土壤速效养分含量。稻鱼共作模式(T2)对冷浸田土壤理化性状影响不显著,但能显著增加土壤速效养分含量,土壤速效钾含量在水稻孕穗期和成熟期分别较对照(CK)增加18.2%和69.2%,从而为水稻生长提供良好的土壤环境和营养,促进水稻生长发育,提高水稻产量。研究表明T1和T2模式能显著提高冷浸田水稻产量,增产范围为8.8%~25.8%,T1模式增产效果最显著,实际产量达到7 623 kg·hm-2。综上所述,垄作模式可以有效地改善冷浸田土壤特性,提高水稻产量,而稻鱼共作模式增产效果主要体现在增加冷浸田水体和土壤的速效养分。 相似文献
14.
为了解羧甲基壳聚糖对水稻氮代谢的影响,采用盆栽试验研究了不同浓度羧甲基壳聚糖对水稻氮代谢,子粒、糙米的全氮、蛋白氮含量,子粒蛋白质产量的影响。结果表明,喷施羧甲基壳聚糖适宜浓度,水稻生殖生长后期功能叶和茎鞘中氮素转运能力比对照强,氮代谢关键酶活性比对照高;糙米中全氮和蛋白氮含量也高于对照。子粒蛋白质产量以0.5%的羧甲基壳聚糖处理最高,比对照增产19.8%。本试验条件下,以羧甲基壳聚糖0.5%浓度处理效果最好,0.25%浓度处理效果次之。 相似文献
15.
灌浆结实期高温干旱复合胁迫对稻米直链淀粉及蛋白质含量的影响 总被引：10，自引：3，他引：10
灌浆结实期是水稻产量与品质形成的关键时期,近年来,由于受全球气候变化和局部地形地貌的影响,我国南方稻区在水稻灌浆结实期频频遭遇高温和伏旱的混合影响,造成水稻产量与品质的同步下降。本研究选用导入空心莲子草基因组DNA构建的籼稻耐旱变异品系H5,在灌浆结实期于人工温室进行高温干旱复合胁迫试验,测定了不同处理稻米直链淀粉与蛋白质含量,旨在深入研究高温干旱复合逆境对稻米品质的影响。试验设6个处理,分别是适温中度干旱(OT-MD)、适温严重干旱(OT-SD)、高温正常供水(HT-WW)、高温中度干旱(HT-MD)、高温严重干旱(HT-SD)和适温正常供水(OT-WW,CK)。除对照外,其余各处理的胁迫时间设10 d、20 d、30 d和40 d。结果表明:灌浆结实期高温胁迫会导致稻米直链淀粉含量下降和蛋白质含量增加,高温胁迫10~40 d的稻米直链淀粉含量比CK降低了1.783~5.987个百分点,稻米蛋白质含量比CK增加了1.178~2.741个百分点;灌浆结实期干旱胁迫同样会导致稻米直链淀粉含量下降和蛋白质含量增加,在中度干旱条件下,胁迫10~40 d处理的稻米直链淀粉含量比CK降低了1.956~6.270个百分点,稻米蛋白质含量比CK增加了1.153~2.944个百分点,在严重干旱条件下,胁迫10~40 d处理的稻米直链淀粉含量和蛋白质含量相对于CK的变异幅度比中度干旱胁迫下的更大;灌浆结实期高温干旱复合胁迫引起稻米直链淀粉含量下降和蛋白质含量增加的幅度均超过单一高温胁迫或干旱胁迫,且其变化幅度随胁迫因子的增加、胁迫强度的增强和胁迫时间的延长而增大;灌浆结实期的前20 d遭遇高温干旱复合胁迫是稻米品质变差的主要原因;在相同胁迫时间内,各处理对稻米直链淀粉和蛋白质含量的胁迫效应按升序排列依次为:高温正常供水(HT-WW)、适温中度干旱(OT-MD)、适温严重干旱(OT-SD)、高温中度干旱(HT-MD)、高温严重干旱(HT-SD)。本研究结论可为水稻的抗旱与抗高温育种与栽培提供参考依据。 相似文献
16.
根际促生菌应用于基质对水稻幼苗生长的影响 总被引：2，自引：1，他引：2
为了研究根际促生菌对水稻幼苗的促生效果，培育高效优质水稻育苗基质，本研究选用五株根际促生菌（LY5枯草芽孢杆菌（Bacillus subtilis），LY11解淀粉芽孢杆菌（Bacillus amyloliquefaciens），X2摩拉维亚假单胞菌(Pseudomonas moraviensis)，X3沙芬西芽孢杆菌（Bacillus safensis），X8绿针假单胞菌(Pseudomonas chlororaphis)）分别与本实验室已筛选出的最适配比基质进行混合制作高效水稻育苗基质，以不添加促生菌为对照，在盆栽条件下，研究根际促生菌对水稻幼苗生长和代谢的影响。结果表明：1）解淀粉芽孢杆菌（LY11）应用于育苗基质对水稻幼苗的促生效果及代谢活性最好。2）在育苗基质中添加根际促生菌后，地上部生物量和壮苗指数均比对照显著增加，增幅分别在18.0%-31.5%和11.38%-23.28%之间。3）添加根际促生菌的育苗基质能够促进水稻幼苗根系的生长，根体积、总根长等均比对照显著增加，且改善了根系形态结构，显著提高了根系活力。4)根际促生菌处理显著促进了水稻幼苗对氮磷养分的吸收，且氮、钾的转运系数显著提高。5）水稻幼苗体内谷氨酰胺合成酶和蔗糖磷酸合成酶活性在促生菌处理下均显著提高。因此，根际促生菌应用于水稻育苗基质能够促进秧苗的生长并提高其代谢活性，本研究结果能够为高效优质水稻育苗基质的研发提供理论支撑。 相似文献
17.
以“安抗1号”和“有机钙博士”两种抗逆剂为材料,以喷清水为对照,在自然高温下进行水稻田间试验,测定剑叶生理指标、水稻产量和稻米品质指标,研究超级早稻灌浆结实期遭遇高温喷施抗逆剂的缓解效果。结果表明：高温发生时,喷施“安抗1号”（T2）和“有机钙博士”（T3）4d后,与喷清水（T1）相比,超级早稻剑叶抗氧化酶活性极显著（P＜0.01）增加,其中SOD活性分别增加17.10%、12.37%,POD活性分别增加13.54%、15.01%,CAT活性分别增加133.86%、87.46%;叶片渗透调节物含量极显著（P＜0.01）增加,其中可溶性蛋白含量分别增加33.58%、34.38%,可溶性糖含量分别增加23.74%,17.30%;MDA含量极显著（P＜0.01）降低28.34%、26.53%。喷施抗逆剂22d后,超级早稻剑叶SPAD衰减率T2、T3处理显著低于T1（P＜0.05）,分别降低3.40个百分点和4.24个百分点;T2、T3处理比T1剑叶SOD活性显著（P＜0.05）增加;POD活性差异不显著;CAT活性和可溶性糖含量均极显著（P＜0.01）增加;可溶性蛋白含量显著（P＜0.05）增加;MDA含量极显著（P＜0.01）降低。喷施抗逆剂处理显著（P＜0.05）提高结实率5.7个百分点,增产11.87%～13.77%。说明高温发生时,喷施抗逆剂能有效缓解高温对超级早稻灌浆结实的危害,改善超级早稻稻米的外观品质及加工品质。 相似文献
18.
High‐intensity ultrasound was evaluated as an alternative method to isolate rice starch without the use of chemicals as in the traditional alkaline steeping method. Surfactants, including sodium dodecyl sulfate (SDS), sodium stearoyl lactylate (SSL), and Tween 80, at 0.1, 0.3, or 0.5% combined with high‐intensity ultrasound were also investigated for rice starch isolation. A rice flour slurry (33%) was subjected to sonication for 15, 30, or 60 min at an amplitude of 25, 50, or 75% and at 40 or 50°C. The starch yield was not significantly affected by the treatment temperature and ranged from 46.7 to 76.2% (starch dry basis) after the sonication treatment; the protein and damaged starch contents of the isolated starches were 0.9–1.7% and 3.1–3.5% (dry basis), respectively. The combination of 0.5% SDS and high‐intensity ultrasound improved the starch yield to 84.9% with low residual protein, however, little improvement was observed with SSL or Tween 80. The pasting properties of isolated starch as measured by a Rapid Visco‐Analyser were affected by the treatment temperature and by the amount of residual protein and damaged starch. The thermal properties of the isolated starch were not changed by sonication and the amylose content remained unchanged. The surface of the isolated starch was not damaged by sonication as shown by scanning electron microscopy. High‐intensity ultrasound, alone or combined with SDS, showed a great potential for rice starch isolation in a short period of time without generating alkaline effluent. 相似文献
19.
Two hydroxycinnamate sucrose esters, 6'-O-(E)-feruloylsucrose and 6'-O-(E)-sinapoylsucrose, were isolated from methanol extracts of rice bran. Soluble and insoluble phenolic compounds as well as 6'-O-(E)-feruloylsucrose and 6'-O-(E)-sinapoylsucrose from white rice, brown rice, and germinated brown rice were analyzed using HPLC. The results demonstrated that the content of insoluble phenolic compounds was significantly higher than that of soluble phenolics in rice, whereas almost all compounds identified in germinated brown rice and brown rice were more abundant than those in white rice. 6'-O-(E)-Feruloylsucrose (1.09 mg/100 g of flour) and 6'-O-(E)-sinapoylsucrose (0.41 mg/100 g of flour) were found to be the major soluble phenolic compounds in brown rice. During germination, an approximately 70% decrease was observed in the content of the two hydroxycinnamate sucrose esters, whereas free phenolic acid content increased significantly; the ferulic acid content of brown rice (0.32 mg/100 g of flour) increased to 0.48 mg/100 g of flour and became the most abundant phenolic compound in germinated brown rice. The content of sinapinic acid increased to 0.21 mg/100 g of flour, which is nearly 10 times as much as that in brown rice (0.02 mg/100 g of flour). In addition, the total content of insoluble phenolic compounds increased from 18.47 mg/100 g of flour in brown rice to 24.78 mg/100 g of flour in germinated brown rice. These data suggest that appropriate germination of brown rice may be a method to improve health-related benefits. 相似文献