乳酸湿热处理改善大米粉性质及粉条品质的研究

主要研究乳酸湿热处理对大米粉性质及其干粉条和湿粉条品质的影响。以水磨籼米粉为原料,通过不同浓度乳酸、湿热以及乳酸与湿热联用的方法对米粉进行处理,研究不同条件下制备的大米粉的糊化特性、溶解度、膨胀率以及干粉条和湿粉条的蒸煮品质和质构品质。实验结果表明:乳酸湿热处理对大米粉糊化特性影响显著,大米粉通过湿热处理、乳酸处理、乳酸湿热联用处理后,大米粉的峰值黏度、谷值黏度、衰减值、最终黏度、回生值都有所降低。在乳酸处理(pH=4)时,峰值黏度最高。乳酸湿热处理对大米粉的溶解度和膨胀度都有一定的影响,与原样相比,被处理过的样品其溶解度、膨胀度都逐渐降低。在粉条蒸煮品质测定中,乳酸处理(pH=4)后,干粉条和湿粉条的断条率、蒸煮损失率都达到最低。在粉条质构品质测定中,经过湿热处理、乳酸处理和乳酸湿热联用处理三种方法处理以后,湿粉条的硬度、咀嚼性均有所下降,在乳酸处理(pH=4)时,湿粉条的弹性达到最大;在湿热处理、乳酸处理和乳酸湿热联用处理中,干粉条的黏度有所下降,在乳酸(pH=4)时,干粉条的弹性达到最大。最终结果:在乳酸处理(pH=4)时,对改善大米粉性质及粉条品质的效果是最优的。     

Thermal characteristics of ohmically heated rice starch and rice flours

ABSTRACT:  Thermal properties of conventionally and ohmically heated rice starch and rice flours at various frequencies and voltages were studied. There was an increase in gelatinization temperature for conventionally heated rice starches since they were pregelatinized and became more rigid due to starch–chain interactions. In addition, there was a decrease in enthalpy (energy needed) for conventionally and ohmically heated starches during gelatinization; thus, the samples required less energy for gelatinization during DSC analysis. Ohmically heated commercial starch showed the greatest decrease in enthalpy probably because of the greatest extent of pregelatinization through ohmic heating. Brown rice flour showed the greatest gelatinization temperature resulting from the delay of starch granule swelling by lipid and protein. Enthalpy of ohmically heated starches at 20 V/cm was the lowest, which was most likely due to the lower voltage resulting in a more complete pregelatinization from a longer heating time required to reach 100 °C. Ohmic treatment at 70 V/cm decreased onset gelatinization temperature of white flour; therefore, it produced rice flour that swelled faster, whereas the conventionally heated sample showed a better thermal resistance.     

Improving Functional Properties of Rice Flours Through Phosphorylation

This research evaluated the chemical, technological, and thermal properties of rice flour modified chemically using phosphorus oxychloride (0.018; 0.030; 0.059; 0.088 and 0.100 g/100 g flour). The phosphorylated rice flours (PRF) obtained showed a decrease in viscosity, but the stability increased significantly as compared to the unmodified flour. The gel force and adhesiveness values decreased with the increase in phosphate groups incorporated. However, cohesiveness and thermal properties did not show significant differences among the native and modified rice flours, with exception for gelatinization enthalpy values. The phosphorylated flours obtained can be used as ingredient, especially in cream soups, salad dressing, and filling.     

Functional,digestibility, and antioxidant properties of brown and polished rice flour from traditional and new‐improved varieties grown in Sri Lanka

Sri Lankan traditional and improved rice varieties were processed into brown and polished rice flours. Samples were analyzed for AM, protein, lipid, total phenolic content, and antioxidant activity. Gelatinization and retrogradation properties were observed in the Rapid Visco Analyzer (RVA) and DSC. The AM content of the samples was high to intermediate (20 to 26%) except for one which was low (17%). Brown rice flour (BRF) samples had lower swelling power, lower RVA viscoamylograph profile, lower gel hardness, lower gelatinization enthalpy but higher gelatinization peak temperature and lower melting enthalpies of its retrograded AP relative to its corresponding polished rice flour (PRF) samples. The BRF showed a lower decrease in peak viscosity in the RVA viscoamylograph as compared to its PRF when treated with α‐amylase indicating inhibition potential. The traditional rice varieties had 68 to 86% higher total phenolic content (TPC) and 86 to 90% antioxidant activity in the BRF samples as compared to the improved varieties. A study on the antioxidant profile of the brown rice of the traditional rice varieties is being undertaken to explore their value as functional foods.     

浅谈糯米淀粉的性状及应用

将不同添加量（0%~25%）的木糖醇添加至糯米粉中构建木糖醇-糯米粉共混体系,探讨木糖醇对糯米粉的糊化特性、热力学特性、凝胶质构、流变学特性和消化特性等性质以及对其制成的汤圆品质的影响。结果表明：木糖醇的添加使共混体系的糊化温度、峰值黏度和终值黏度有所提高,体系的短程有序程度降低,体系表现为假塑性流体,具有剪切稀化行为。与对照组相比,木糖醇添加量为10%时,共混体系的回生值和凝胶硬度最小,分别为405 cP和14.952 g,体系抗性淀粉含量为29.88%,表现出较好的抗回生性。但高浓度木糖醇（15%~25%）促进体系发生短期回生,增加其回生值和弹性。另外,木糖醇的添加显著降低了汤圆的冻藏水分损失率和汤汁透过率,其中添加10%的木糖醇制成的汤圆具有更高的硬度、弹性、回复性以及咀嚼性,食用品质最好。本研究为木糖醇改善糯米粉品质以及糯米粉产品开发提供参考。

     

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.     

黑血糯米粉的物化性质研究

研究了黑血糯的营养成分,黑血糯淀粉的颗粒形貌和结晶性质,糊的凝沉性,冻融稳定性以及糊的粘度曲线。结果表明黑血糯的蛋白质含量高,氨基酸组成合理,结晶度高,糊化温度高,糊的凝沉性低,冻融稳定性一般。可知酸、碱可以促进黑血糯的糊化,而蔗糖则有一定的抑制作用。     

Characterization of the Interactions between Cereal Flour and “Nata Puree” in Batter

This study aimed to characterize the interactions between cereal flour (rice, wheat, and barley) and “nata puree” (NP), a disintegrated bacterial cellulose (BC) in the presence of a water-soluble polysaccharide, with powder-dispersion activity. Pasting properties of cereal flour with additives were analyzed using a Rapid Visco Analyzer, and disintegrated BC in water (BCW), three water-soluble polysaccharides: (1,3)(1,4)-β-glucan, tamarind seed gum, and birchwood xylan, and the corresponding NPs were used as additives. For rice flour, additional BCW or NPs increased the initial and the peak viscosity. The addition of water-soluble polysaccharides produced the opposite trend: viscosity increased from the peak time to the end of measurements. For wheat flour, the addition of BCW or NP delayed the peak time and increased peak viscosity; the increase was maintained till the end of measurements. For barley flour, the additional BCW or NP caused a higher gelatinization rate and increased viscosity at the starch-retrogradation stage. Next, static gelatinization of a rice flour suspension in NP was successfully accomplished before placing it in a vessel; NP concentration in the gel significantly affected the firmness. Thus, the dynamic and unique interactions between various cereal flours and cell-wall polysaccharides in NPs can increase the flours'' potential; static gelatinization of cereal flour with NP could expand flours'' application range in both current and next-generation cooking.     

Fatty acids composition and rheology properties of wheat and wheat and white or brown rice flour mixture

Manufacturing of bread from rice flour only presents technological difficulty because the rice is gluten-free and gluten is the most important structure forming protein. By using wheat and rice flour mixture, this problem can be avoided, and end product is enriched by rice-oil constituents. In this paper fatty acids composition, with an emphasis on total saturated, and total unsaturated fatty acids, rheological and baking properties of wheat–rice flour mixture (70:30 w/w) were investigated. The results show that wheat–rice flour mixture has better fatty acids composition with higher content of stearic, arachidic, lignoceric, oleic, and phthalic acids compared to wheat flour. Also, wheat flour did not include myristic, arachidic, lignoceric and linolenic acids, so rice flour addition made fatty acids profile richer as number of constituents is higher, nine instead six. The content of total unsaturated fatty acids content was higher in wheat–brown rice flour mixture than in wheat flour and in wheat–white rice flour mixture. When rice flour was added to wheat flour the rheological properties were changed: flour mixture had less water absorption, less degree of softening, longer development time, higher gelatinization temperature, but better stability and finally, better quality number and group than wheat flour. So, the wheat and rice flour mixture can be considered as a good quality flour and can be used for making good quality wheat-rice bread and cake.     

普鲁兰多糖对籼米粉凝胶及老化特性的影响

探究不同添加量的普鲁兰多糖(0%、2%、4%、6%、8%)对籼米粉糊化特性、流变特性、凝胶质构以及微观结构的影响。结果表明,普鲁兰多糖的添加使米粉的糊化特性、流变特性、凝胶质构和微观结构发生显著变化。随着普鲁兰多糖添加量的增加,混合粉的峰值黏度、最低黏度、崩解值、回生值、弹性模量、黏性模量均逐渐降低,糊化温度略有升高,表明普鲁兰多糖抑制了大米淀粉的糊化;X-射线衍射的分析表明普鲁兰多糖的添加降低了淀粉的重结晶度,抑制了淀粉老化;普鲁兰多糖添加后的凝胶呈现出多孔状结构,表明淀粉连续性的凝胶结构被破坏,从而导致凝胶的硬度、弹性、黏聚性、胶着度、咀嚼性逐渐降低。     

发芽糙米粉理化性质研究

对发芽粳糙米粉和发芽籼糙米粉基本成分、微观结构、热焓特性及糊化性质(RVA)等进行了研究。结果表明:与糙米粉相比,发芽糙米粉中粗脂肪含量降低,蛋白质含量增加,总淀粉含量降低,粗纤维、灰分等含量变化不明显;随着发芽时间的增长,糙米粉峰值粘度、最低粘度、崩解值、最终粘度和回升值都降低;发芽糙米粉峰值温度、起始温度、终止温度及焓值均比糙米粉低,且籼糙米高于粳糙米。扫描电镜结果显示:发芽后糙米粉颗粒结构变得较疏松,棱角不太明显,发芽籼糙米粉颗粒结构较发芽粳糙米粉颗粒结构更加疏松,淀粉颗粒体积更小。      

马铃薯-籼米粉特性及其挤压成型品质

为推进马铃薯主食化研究,将马铃薯全粉和籼米粉混合并通过螺杆挤压技术制备米粉。研究添加马铃薯全粉对籼米粉糊化、流变、凝胶质构、微观结构以及对米粉蒸煮、质构和色差等品质的影响。结果表明,与纯籼米粉相比,马铃薯全粉增加,混合粉糊化后的糊化特征参数、弹性模量、黏性模量、凝胶强度均降低,凝胶流动性更好,呈现较少、均匀程度相同的孔状结构,且连接较紧密。米粉的蒸煮时间、透射比亦降低,而吐浆值和断条率升高。米粉质构特征值呈降低趋势,与凝胶质构变化一致。添加20%马铃薯全粉能使米粉亮度值L显著减小,红值a显著增大;30%马铃薯全粉能使黄值b显著增大。综合各项指标,马铃薯全粉添加量在30%以内,米粉仍具有可接受的品质。     

Effects of three reducing agents on pasting properties of stored rice

The effects of three reducing agents (dithiothreitol, ascorbic acid, and tea polyphenols) on pasting properties of fresh and aged rice were investigated using Rapid Visco Analyzer. Results showed that ascorbic acid did not only significantly increase peak viscosity (PV) and breakdown of aged rice in a concentration dependent manner (p<0.05), but also decreased its setback significantly (p<0.05). Dithiothreitol increased the PV, breakdown and setback of the aged rice. Importantly, the extent of ascorbic acid enhancing PV of the aged rice was higher than that of dithiothreitol, and showed positive dose‐effect relationship. Compared with ascorbic acid and dithiothreitol, tea polyphenols only significantly decreased setback of the aged rice (p<0.05). It was concluded that ascorbic acid was the most effective improver on pasting properties of aged rice as compared to dithiothreitol or tea polyphenols, especially in increasing PV and breakdown, and in decreasing setback. This showed rice ageing included, but was not limited, to the formation of disulfides, and more changes of ageing would involve hydrogen bonding and hydrophobic interactions. The different influences of SDS on fresh rice and aged rice also confirmed these findings to a certain extent. The improved role of ascorbic acid was ascribed to enhancing water absorption capacity, soluble solid content and granule swelling capacity of the aged rice.     

酸湿热处理对米粉性质的影响研究

本文在实验室条件下采用酸湿热处理米粉样品,测定处理前后米粉的化学组成变化、颗粒形貌、结晶性质、红外图谱、热力学性质、糊化性质和消化特性。研究表明,经过酸湿热处理后的米粉蛋白质含量减少较多,其它的粗脂肪、还原糖变化不大。显微结构分析得出米粉保持原有的团粒结构,但偏光十字稍微变得模糊,颗粒的有序结构遭到一定破坏,少数淀粉脐点处出现凹坑。红外图谱变化不大,结晶度变小。处理后米粉的起糊温度升高,糊的峰值粘度降低,吸收焓减小。酸湿热处理可以一定程度下提高米粉中慢速消化淀粉(SDS)的含量。     

蛋清蛋白添加对籼米-绿豆粉粉质特性及挤压米粉丝品质特性的影响

将籼米粉、绿豆粉和蛋清蛋白粉按照一定的比例复配,开发高纤维含量的杂粮米粉丝。研究了绿豆和蛋清蛋白的添加对米粉糊化特性、流变特性以及挤压米粉丝微观结构、蒸煮特性和质构等品质特性的影响。结果显示:添加一定量的绿豆粉和蛋清蛋白粉后,混合粉的峰值黏度、最低黏度、最终黏度、回生值、弹性模量、黏性模量均逐渐下降。随着绿豆粉的添加(25%,50%),米粉的蒸煮时间、断条率、蒸煮损失和吸水率均上升,硬度降低,表明米粉的品质显著降低,由扫描电镜图可以发现,加了绿豆粉之后米粉截面变得越来越粗糙,裂纹和孔洞明显增多。但当加入7.5%的蛋清蛋白后,米粉的蒸煮时间、蒸煮损失和断条率均下降,质构特性有一定程度的改善,表明蛋清蛋白良好的凝胶特性有助于提升高纤维含量挤压米粉丝的品质。     

白糯小麦粉与糯米粉物化特性的比较

本试验研究了白糯小麦粉与普通小麦粉、糯米粉物化性质的差异,测定了白糯小麦粉、普通小麦粉和糯米粉的膨胀性、黏度特性、持水能力、糊透明度、冻融稳定性、消化性和糊化回生特性。结果表明,随温度的升高,白糯小麦粉、普通小麦粉和糯米粉的膨胀度随温度的升高呈递增趋势,但在较高温度下,白糯小麦粉的膨胀度高于糯米粉;与普通小麦粉比,白糯小麦粉有较高的峰值黏度、崩解值和较低的谷黏度、终黏度、回生值,糊化时间短,糊化温度低,不易消化;与糯米粉相比,白糯小麦粉的水合能力低,糊透明度差,峰值黏度、谷黏度、崩解值、终黏度和回生值低,糊化时间短,糊化温度高,易消化。白糯小麦粉的冻融稳定性好、抗回生能力强。     

Effect of soil moisture stress from flowering to grain maturity on functional properties of Sri Lankan rice flour

Functional properties of flour from rice variety BG 250 (short‐season) and BG 359 (long‐season) exposed to soil water stress from flowering to grain maturity were investigated. Protein content was reduced in both varieties but lipid was reduced only in BG 359 in response to soil moisture stress. AAM content decreased in BG 250 but unaffected in BG 359. Water stress increased swelling power, onset of pasting, peak viscosity, granular breakdown, gel hardness, and cohesiveness in both varieties. Gelatinization temperatures in both varieties were unaffected by water stress, while gelatinization enthalpy was increased in BG 359 but unchanged in BG 250. A double endotherm (type I and type II) appeared in AM–lipid complex in all the flour samples. Type I AM–lipid complex was reduced in BG 359 in response to water stress. Only a single endotherm appeared in the re‐formed AM–lipid complex in gelatinized starch. The magnitude of the ΔH of re‐formed AM–lipid complex was reduced in BG 359 in response to soil moisture stress, but unaffected in BG 250. Water stress decreased AP retrogradation in BG 359 while it was unaffected in BG 250.     

Effects of potato starch on the characteristics,microstructures and quality attributes of indica rice flour and instant rice noodles

The effects of partial replacement (0%–20%, w/w) of rice flour by potato starch (PS) on the physicochemical properties, microstructures, texture and in vitro digestibility of indica rice flour (IRF) and instant rice noodles (IRN) were systematically investigated. Accordingly, the addition of PS significantly increased the peak viscosity (2876.00–3221.00 mPa·s) and tan δ values (0.14–0.22) but lowered the setback values (2169.00–1036.50 mPa) of the pastes. Rice noodles with 5%–15% PS (PS and IRF at the mixing ratios of 5:95, 10:90, 15:85 and 20:80, respectively) addition exhibited modulated appearance and textural properties. The mutually exclusive phosphate groups of PS facilitated the expansion of starch granules, contributing to the formation of more compact microstructure and higher-ordered crystalline structures (confirmed by scanning electron microscope and X-ray diffraction), endowing rice noodles with better cooking and digestive attributes, and visibly increased slowly digestible starches content (26.09%–31.34%). The quality attributes of rice noodles could be accurately predicted by the physicochemical properties of rice flour referring to Pearson’s correlation analysis. The study demonstrates that the blending of PS is both an effective and economical pathway in improving the nutritional and textural properties of IRN.     

Physicochemical properties of rice flour as affected by alkaline soaking and washing treatments

Effects of alkaline [NaOH, saturated Ca(OH)₂ and/or limewater] soaking and subsequent washing (with water vs. without washing) treatments on physicochemical properties of rice flour were investigated. Alkaline soaking treatment generally caused a loss of granule angularity but some birefringence was observed for unwashed alkali-soaked flour granules. After soaking, protein content of the flours significantly (P < 0.05) decreased but swelling power significantly (P < 0.05) increased compared to the control (soaked in water). The washed flours had lower protein content than unwashed flours (3.77–6.87% vs. 5.26–7.87%). The NaOH-soaking treatment yielded higher swelling power and solubility, respectively, for unwashed and washed flours. Alkaline soaking increased breakdown but decreased pasting temperature, trough viscosity, final viscosity and setback of the paste compared to the control. Compared to the control, hardness of soaked flour paste was lower due to lower final viscosity and setback. Overall, physicochemical properties of rice flour could be modified by alkali-soaking and washing treatments.     

没食子酸与大米淀粉的相互作用

该研究探讨了没食子酸对大米淀粉溶解度、膨胀度、糊化特性及流变学特性的影响,并对淀粉-没食子酸复合物的分子结构及晶体结构进行表征。结果表明：没食子酸显著增加了大米淀粉的溶解度,降低了大米淀粉的膨胀度,糊化温度和糊化焓值（p<0.05）,表明没食子酸能抑制淀粉的糊化膨胀并降低其热稳定性。没食子酸降低了大米淀粉的糊化粘度值和回生值,说明没食子酸能减少淀粉分子链间的相互交联,并抑制大米淀粉的老化。没食子酸与大米淀粉的混合体系呈现典型的假塑性流体,具有剪切变稀性;没食子酸显著降低了淀粉的储存模量和损耗模量值,没食子酸-淀粉凝胶体系的粘弹性降低,说明没食子酸对淀粉凝胶结构具有破坏作用。红外光谱表明,没食子酸-淀粉复合物在1045/1022 cm-1峰强度比值减小,说明没食子酸可降低大米淀粉的有序性,二者的相互作用以氢键为主。X-衍射图谱表明,复合物在12.7 °处出现新的衍射峰,表明没食子酸能与大米淀粉发生相互作用形成了特殊的晶体结构。该研究可为没食子酸在淀粉基功能性食品中的应用提供理论指导。