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1.
蒸煮工艺和化学成分对米饭应力松弛特性的影响 总被引：6，自引：2，他引：6
用4种工艺制作米饭，用质构仪测定米饭的应力松弛曲线，并分析米饭的主要化学成分，研究米饭的应力松弛参数与化学成分的关系，为米饭蒸煮工艺的优化和新型炊具的开发提供基础数据。结果表明，不同工艺蒸煮的米饭的应力松弛参数有较大的差异性，较低温度下蒸煮的米饭的硬度较大，较高温度下蒸煮米饭的黏性较大。米饭的平衡弹性系数E0为15.754～89.323 Pa；衰减弹性系数E1为34887.528～35213.051 Pa；松弛时间τ为0.130～0.179 s；松弛非线性指数n为0.019～0.054，黏度系数η为4538.085～6248.998 Pa·s。米饭为具有一定交联程度的黏弹性体，其松弛参数与米饭的化学成分有较大关系，蛋白质含量较高的米饭的E0、τ和η较大；脂肪含量较高的米饭的E0较小；直链淀粉含量较高的米饭的E1和τ较小。建立的基于米饭的化学成分与米饭松弛参数的多元幂函数式方程具有较高的拟合精度。 相似文献
2.
为了制备风味良好的鲣鱼调味基料,本试验以鲣鱼蒸煮液(STCL)为原料,在酶解和脱腥基础上,采用感官评价、电子鼻技术结合主成分分析(PCA)及线性判别分析(LDA),通过正交试验优化美拉德工艺,并对鲣鱼蒸煮液酶解液美拉德产物进行氨基酸组成成分分析和必需氨基酸营养评价。结果表明,电子鼻技术结合LDA优于PCA,更能客观地区分不同条件下鲣鱼蒸煮液酶解液美拉德反应产物的风味差异;鲣鱼蒸煮液酶解液美拉德反应最优工艺条件为:添加木糖-葡萄糖1:2,在110℃下加热45 min,在此条件下,美拉德产物鱼香味浓郁,色泽呈黄棕色,氨基酸总量为7.036 g·100g-1,必需氨基酸含量为2.888 g·100g-1,必需氨基酸指数(EAAI)为64.034,说明鲣鱼蒸者液美拉德反应产物营养价值较高,是研发海鲜调味料的理想基料。本研究结果为鲣鱼调味基料的开发提供了一定的理论依据。 相似文献
3.
超低酸预处理结合酶解提高玉米秸秆糖化效率 总被引：1，自引：1，他引：0
为提高纤维素酶解糖化的效率,该文采用超低浓度硫酸水解预处理废弃玉米秸秆。重点考察了不同酸浓度、反应温度、反应时间条件下超低浓度酸水解及后续酶解的总还原糖、葡萄糖及木糖的产率,详细叙述了总还原糖及各种单糖在酸水解及酶解过程中的转化规律,通过正交试验确定酸水解的最佳工况为酸浓度0.1%,反应温度160℃,反应时间55 min,搅拌180 r/min,固液比1∶10。酸水解后进行酶解(酶用量5%,pH值4.6,时间24 h,温度50℃)得到还原糖、葡萄糖、木糖产率分别为56.22%、16.97%、18.83%。通过红外光谱和纤维素分析仪对酸水解和酶解后的残渣进行分析可知,纤维素、半纤维素的转化率分别为88.52%、95.18%,进一步计算还原糖、葡萄糖、木糖的转化率为88.11%、44.86%、72.49%。该方法较大程度避免了还原糖在酸水解过程中的降解,保证了半纤维素还原糖的转化效率,进一步提高了总还原糖的产率,为超低酸水解在燃料乙醇领域提供了新的应用途径。 相似文献
4.
合理降解烤后烟叶中的淀粉和纤维素含量已成为提高烟叶质量的关键工艺之一。本研究对分离自烤烟叶面的产淀粉酶细菌菌株解淀粉芽孢杆菌(Bacillus amyloliquefaciens A1)和产纤维素酶细菌菌株短小芽孢杆菌(B.pumilus C1)进行发酵培养,提取粗酶液,检测酶活性并应用于初烤烟叶上。通过设计不同酶量、作用时间、相对湿度和温度的方法考察这两种酶制剂对烟叶(Nicotiana tabacum K326)中淀粉和纤维素的降解效果。结果表明,菌株A1主要产α-淀粉酶,酶活力为7×105U/mL,菌株C1以产内切酶为主,酶活力为6×103U/mL;在温度40℃、湿度70%条件下作用96h,用菌株A1所产淀粉酶制剂4×107U/kg处理后的烟叶总糖增加率为12.78%,还原糖增加率为12.03%,菌株C1所产纤维素酶制剂4×105U/kg处理后的烟叶总糖增加率为13.87%,还原糖增加率为18.07%。研究结果提示,利用从烟叶表面分离的产酶菌株进行发酵生产的酶制剂可降解初烤烟叶中淀粉和纤维素,提高还原糖含量,可望在烟叶加工过程中得到应用。 相似文献
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6.
混配比例及加工方式对“降糖稻1号”稻米产品抗性淀粉含量的影响 总被引：1，自引：0，他引：1
以高抗性淀粉含量功能性粳稻品系"降糖稻1号"稻米为主要材料,研究其与不同比例稻米混配后经蒸煮、膨化、制作米粉及发酵加工后,对稻米产品直链淀粉含量和抗性淀粉(RS)含量的影响。结果表明,稻米中RS含量随加工温度和加工压力的提高而大大降低,表明"降糖稻1号"不宜高温高压蒸煮、膨化、加工米粉和发酵食品。"降糖稻1号"与"金丰"稻米按不同比例混合蒸煮后,其直链淀粉含量、RS含量及蒸煮品质有明显改善,"降糖稻1号"与"金丰"稻米以2:1混配,不仅明显改善米饭的食味,而且RS含量能保持较高的水平。 相似文献
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8.
苎麻纤维质酶降解生产生物燃料乙醇的工艺 总被引：10，自引：2，他引：10
在微生物预处理苎麻韧皮的基础上，进行了pH值、酶用量、葡萄糖浓度和原料处理方式等对苎麻纤维质酶降解的单因子试验和正交试验。结果表明，苎麻纤维质酶解的起始pH值为5.0左右，总糖转化率最高，达72.361％；在一定的酶浓度范围内，随着酶量的增加，苎麻纤维质的总糖转化率提高，酶的适宜用量为：木聚糖酶5％、纤维素酶10％；水解液中葡萄糖浓度在0.5％以下时，苎麻纤维质的总糖转化率不受影响，葡萄糖浓度在0.5％以上时，随着水解液中葡萄糖含量的增加，总糖转化率下降；苎麻纤维质酶解过程中，对原料进行机械处理，有利于提高酶的水解效率；苎麻纤维质酶解的最适条件为：pH值4.5～5.5、纤维素酶浓度8%～11％、葡萄糖浓度小于0.5%、原料不洗直接进行剪碎处理。 相似文献
9.
低温挤出-多酶协同降解脱胚玉米中淀粉的机理 总被引：1，自引：1，他引：0
为了改变目前挤出酶解谷物淀粉仅添加一种酶制剂(α-淀粉酶),只能降解淀粉的α-1,4糖苷键,不能降解支链淀粉的α-1,6糖苷键,限制淀粉转化成葡萄糖的收率进一步提高的现状,该文应用低温(≤80℃)挤出-多酶(α-淀粉酶、糖化酶、普鲁兰酶)协同降解技术,制备挤出过程中物料的石蜡显微制片,观察脱胚玉米经低温挤出-多酶协同降解处理后,细胞壁、细胞中的淀粉颗粒和蛋白质颗粒的分布状况以及淀粉含量、糊化度、可溶性糖含量的变化。结果表明:在挤出过程中,淀粉发生糊化和降解,表观淀粉质量分数减少,从81.50%减少到74.40%,可溶性糖质量分数增加,从1.07%增加到2.26%,挤出过程中加入酶制剂后这种变化更加明显。添加单一α-淀粉酶表观淀粉质量分数从79.72%减少到69.16%,可溶性糖质量分数从6.54%增加到7.90%。添加α-淀粉酶和糖化酶表观淀粉质量分数从81.42%减少到72.45%,可溶性糖质量分数从11.65%增加到14.71%。添加α-淀粉酶和普鲁兰酶表观淀粉质量分数从81.31%减少到70.31%,可溶性糖质量分数从6.74%增加到8.29%。添加α-淀粉酶、糖化酶、普鲁兰酶3种酶时淀粉质量分数从81.06%减少到69.05%,可溶性糖质量分数从11.25%增加到16.35%。因此,3种酶(α-淀粉酶、糖化酶、普鲁兰酶)协同作用对淀粉降解以及可溶性糖含量的增加作用效果最好。显微切片的分析结果表明:添加3种酶制剂(α-淀粉酶+糖化酶+普鲁兰酶)的切片,细胞结构中淀粉颗粒被降解破坏的程度大于添加1种(耐高温α-淀粉酶)、2种(α-淀粉酶+糖化酶,或者α-淀粉酶+普鲁兰酶)酶制剂的细胞结构中淀粉颗粒被降解破坏的程度。低温挤出-多酶协同降解后,脱胚玉米挤出物的总淀粉含量降低、可溶性糖含量增加,糊化度增加。试验表明:添加3种酶制剂协同降解脱胚玉米中淀粉的作用效果优于添加1种酶制剂或2种酶制剂的淀粉降解效果,为进一步提高淀粉转化成葡萄糖的收率提供科学依据。 相似文献
10.
为明确低O2高CO2贮藏环境对马铃薯块茎淀粉-糖代谢的影响,本试验以大西洋马铃薯为试验材料,研究体积分数为5%O2+2%CO2(CA1)、5%O2+4%CO2(CA2)、5%O2+6%CO2(CA3)、5%O2+8%CO2(CA4)及5%O2+10%CO2(CA5)的气体环境对马铃薯在4℃贮藏期间块茎中糖类、淀粉及淀粉-糖代谢相关酶[腺苷二磷酸葡萄糖焦磷酸化酶(AGPase)、尿苷二磷酸葡萄糖焦磷酸化酶(UGPase)、淀粉磷酸化酶(SP)及转化酶(INV)]活性的影响,并对块茎中还原糖含量的变化与淀粉-糖代谢相关因子进行相关性分析。结果表明,适宜的低O2高CO2贮藏环境可有效抑制淀粉含量、AGPase活性、UGPase活性的下降,并且能够抑制还原糖、蔗糖、果糖、葡萄糖含量及SP、INV活性的上升,CA1环境贮藏的马铃薯块茎在整个贮藏期间淀粉含量显著高于CK(P<0.05),还原糖、蔗糖、果糖及葡萄糖含量显著低于CK(P<0.05),AGPase、UGPase活性显著高于CK(P<0.05),而SP、INV活性均显著低于CK(P<0.05);相关性分析结果表明,还原糖含量与淀粉含量、AGPase活性、UGPase活性呈极显著负相关(P<0.01),与葡萄糖含量、果糖含量、SP活性及INV活性呈极显著正相关(P<0.01)。综上,马铃薯在CA1(5%O2+2%CO2)环境下贮藏可有效延缓块茎低温贮藏期间“糖化”现象的出现,AGPase、UGPase、SP、INV在贮藏过程中起到了一定的调控作用。本研究结果为加工型马铃薯的安全贮藏及明确“低温糖化”机理提供了理论依据。 相似文献
11.
The objective of this study was to investigate the effects of milling and cooking conditions of cooked rice prepared from cultivar Koshihikari on in vitro starch digestibility and in vivo glucose response in humans. In addition, compression and adhesiveness tests were conducted for texture analysis of the cooked rice. Brown rice (BR) and surface‐abraded BR (SABR, ≥99.5% of the original weight) were digested more slowly than white rice (91% of the original weight) when cooked rice grain was used for the in vitro test, but they were digested more rapidly in the initial stage of the reaction when cooked rice ground by a meat grinder was used. The increase in water added for cooking significantly increased the extent of starch digestion with BR and SABR. The changes in blood glucose levels after the ingestion of cooked rice were dependent on the sample type. The cooking conditions dramatically influenced the glucose response after the ingestion of BR. A significant correlation was found between blood glucose levels at 45 min and the extent of starch digestion with ground samples, whereas no relationship was found with cooked rice grain samples for in vitro digestibility. 相似文献
12.
The effect of instant cooked rice made from giant embryo mutant or ordinary normal rice on the glucose metabolism and antioxidative defense system in mice under a high‐fat (HF) diet condition was investigated. The animals were randomly divided and given experimental diets for seven weeks: normal control diet, HF diet, and HF diet supplemented with instant normal white, normal brown, giant embryonic white, or giant embryonic brown rice. At the end of the experimental period, the HF mice showed a marked increase in the blood glucose level, insulin concentration, and plasma and erythrocyte lipid peroxidation and a significant decrease in the glycogen level relative to the control group. However, diet supplementation with instant cooked giant embryonic and normal brown rice counteracted this high‐fat‐induced hyperglycemia and oxidative stress through regulation of the glucose‐regulating and antioxidant enzyme activities. The giant embryonic brown rice was the most effective in improving the glucose metabolism and antioxidant defense status in mice under the HF diet condition. The results demonstrate that the giant embryo rice mutant may be useful in the development of instant cooked rice with strong hypoglycemic and antioxidative properties. 相似文献
13.
Eight U.S. long‐grain rice cultivars were studied for chemical compositions, physicochemical properties, and leaching characteristics in relation to hardness and stickiness of rice flour paste and cooked rice. There were differences in the chemical composition of rice kernels among the eight rice cultivars, including crude protein (6.6–9.3%), crude fat (0.18–0.51%), and apparent amylose content by iodine colorimetry (19.6–27.0%). Differences were also observed in gelatinization temperatures and enthalpies, pasting temperatures and viscosities, leached/insoluble amylose, soluble solids, and hardness and stickiness of rice flour pastes and cooked rice kernels. The quantity and molecular size distribution of the leached starch molecules varied greatly among the samples. Protein and crude lipid contents negatively correlated with hardness of rice flour paste and cooked rice, but positively correlated with stickiness. Apparent amylose content correlated with gel properties but not cooked rice texture, whereas the ratio of A and short B chains to long B chains of amylopectin correlated significantly with cooked rice texture. 相似文献
14.
Jeffrey A. Byars 《Cereal Chemistry》2003,80(1):87-90
The effect of processing conditions in an excess steam jet cooker on the degradation of waxy maize starch was studied. The temperature of the steam, the flow rate of the starch slurry, and the concentration of starch were determined to influence the extent of degradation. The viscosity of concentrated solutions of the jet‐cooked product and the intrinsic viscosity of dilute solutions were used as measures of the extent of molecular degradation. The viscosity decreased at higher reaction temperatures, and at higher team‐to‐starch ratios. Multiple passes through the jet cooker decreased the viscosity dramatically for the first two passes, but little additional change was observed for further passes. The results show that mechanical and thermal degradation effects are both important in the jet cooking of waxy maize starch, although the primary effect is due to mechanical degradation. 相似文献
15.
Yang CZ Shu XL Zhang LL Wang XY Zhao HJ Ma CX Wu DX 《Journal of agricultural and food chemistry》2006,54(2):523-528
As the staple food of over half the world's population, hot cooked rice high in resistant starch (RS) is of particular interest, which will have greater impact in the dietary prevention of diabetes and hyperlipidemia. A mutant rice high in RS in hot cooked rice, described as RS111, was comparatively studied with the wild type and common rice. Despite obviously low RS content in the raw milled rice, the RS content in the hot cooked rice of mutant RS111 was significantly higher than that of the wild type and common rice and, correspondingly, in vitro starch hydrolysis by porcine pancreatic alpha-amylase tends to be incomplete with low hydrolysis extent for the cooked mutant rice high in RS. Obvious differences in physicochemical properties, starch granule morphology, pasting properties, thermal properties, and X-ray diffraction pattern were observed among the mutant RS111, wild type, and common indica rice. The high-RS mutant was characterized by significantly higher apparent amylose content and crude lipid content, higher percentage of oval-shaped granules and bigger oval size, reduced paste viscosity, and low onset temperature, peak temperature, final temperature, enthalpy of gelatinization, and crystallinity. 相似文献
16.
Tran TU Suzuki K Okadome H Ikezaki H Homma S Ohtsubo K 《Journal of agricultural and food chemistry》2005,53(4):1108-1118
Changes in the taste of japonica, hybrid, and indica brown and milled rice, stored for 10 months at low (5 degrees C, 65-70% relative humidity) and room temperatures were observed by physicochemical analyses and a novel method using a taste sensing system. During storage, some properties increased or decreased while others were fairly constant. The main taste components of cooked rice such as sweetness (sucrose) and umami tastes (glutamic acid and aspartic acid) were reduced during storage, whereas glucose and fructose increased. The increase of fat acidity and consequent decrease of the pH value of the cooking solution may contribute to the off-taste of cooked stored rice. A taste sensing system with 10 lipid membrane sensors was also used to classify new and old rice samples using principal component analysis. Fresh and room temperature stored japonica and indica rice could be clearly distinguished; however, it was not possible to differentiate the samples stored at low temperature. 相似文献
17.
Physicochemical characteristics of chalky rice kernels were compared with those of vitreous kernels, and the effects of chalky kernels on sensory quality of cooked rice were investigated. Chalky kernels were compared with vitreous kernels using image analysis and amylose contents. Because cooked rice is prepared through soaking and cooking, the changes in water absorption index (WAI) during soaking (15, 30, 60, and 90 min) and the structural changes during cooking (0, 3, 6, and 9 min) in chalky and vitreous kernels were investigated using image analysis and scanning electron microscopy. The effects of various proportions (0, 4, 6, 8, 10, and 15%) of chalky kernels on sensory quality of cooked rice were also studied. The chalky kernels tended to be smaller in kernel area, maximum diameter, minimum diameter, and perimeter than vitreous kernels. Amylose content in chalky kernels was slightly lower than that in vitreous kernels. WAI of chalky kernels was higher than that of vitreous kernels. The effects of chalky kernels on the sensory quality of cooked rice were not significant unless the proportion of chalky kernels was ≥15%. A sensory panel agreed that the overall sensory quality of cooked rice with 15% chalky kernels was the lowest among the samples tested. 相似文献
18.
M Clower J P McCarthy D M Rains 《Journal of the Association of Official Analytical Chemists》1985,68(4):710-711
Two studies were conducted to determine the effect that cooking has on the level of residues of ethylene dibromide (EDB) in rice. In the first study, 4 samples of long and medium grain polished white rice containing 113, 295, 956, and 1568 ppb EDB were cooked according to typical label directions. Three batches of cooked rice were prepared from each sample of polished rice and frozen until analysis; each batch was analyzed in duplicate. EDB levels in all cooked rice samples were less than 10 ppb. In the second study, conducted jointly by the Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA), a sample of medium grain polished white rice containing about 1600 ppb EDB was cooked by each laboratory. Overall average EDB levels in rice analyzed immediately after cooking were 16 and 37 ppb for FDA and EPA, respectively. The corresponding frozen samples contained 8 and 39 ppb EDB. The 2 laboratories exchanged these frozen samples and reanalyzed them to check variability in the analytical procedure. FDA found 49 ppb EDB in the sample cooked by EPA and EPA found 8 ppb EDB in the sample cooked by FDA, thus indicating that analytical methodology was not a major source of variability. The range of EDB levels was therefore attributed to minor differences in the way the rice was cooked or handled immediately after cooking. 相似文献
19.
Ming‐Hsin Lai Kai‐Li Liu Pei‐Yin Chen Nai‐Jhen Ke Junne‐Jih Chen Jih‐Min Sung Yu‐Ling Wu Sheng‐Dun Lin 《Cereal Chemistry》2016,93(2):150-155
Two cooked brown rice and six white rice varieties were selected for assessing the variations in predicted glycemic index (pGI) determined by using in vitro starch digestion and the glycemic index (GI) determined in vivo. Marked varietal differences in apparent amylose content, dietary fiber content, pGI, and GI were observed. Most of the tested rice samples were classified as medium‐GI foods. The varieties Khazar and Taikeng 9 were categorized as high‐GI foods when bread was used as the reference. But brown and white rice samples of TRGC9152 and Taichung Sen 17 fell into the low‐GI category when glucose was used as the reference. A significant correlation coefficient (r = 0.946) was found between pGI and GI of rice samples by using bread as the reference with a regression equation of GI = 28.778 + 0.717 × pGI (R2 = 0.8951, P ≤ 0.001). Overall, the in vitro pGI measurement is a rapid and useful method to predict the GI of cooked rice samples. 相似文献
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Brown rice kernels (japonica type) were soaked in water at different temperatures (25 or 50°C) before cooking to a moisture content of 20 or 30%. Soaked brown rice was cooked in either the soaking water (SW) or in distilled water (DW) (rice solids to water ratio 1:1.4). Color, texture, and in vitro digestive properties of the cooked rice were examined. When the soaking temperature was higher (50°C vs. 25°C), water absorption and starch leaching were greater. To reach 20% moisture, the rice required 1 hr of soaking at 50°C but 2 hr of soaking at 25°C. Both the moisture content of the soaked rice and the soaking temperature affected the texture of the cooked brown rice. Rice that attained 20% moisture content during soaking was harder and less adhesive when cooked compared with rice that attained 30% moisture content. The rice soaked at 50°C was slightly softer but more adhesive when cooked than rice soaked at 25°C. The soaking temperature and moisture content of the rice kernels also affected the digestive properties of the cooked rice. The cooked brown rice that had attained 30% moisture before cooking was digested to a greater extent than rice that had attained 20% moisture. Even at equal moisture content, the rice soaked at the higher temperature (50°C) was digested more readily. It was assumed that the amount of soluble material leached during soaking differed according to the soaking temperature and moisture content, which subsequently affected the texture and digestive properties of the cooked brown rice. The rice cooked in its own soaking water was harder and more adhesive, had higher levels of resistant starch (RS), and exhibited smaller glycemic index (GI) values than its counterpart cooked with distilled water. This result indicated that the soluble material leached during soaking made the cooked rice harder and less digestible, perhaps due to interactions between these molecules and the gelatinized rice during cooking. 相似文献