不同软米品系对方便米饭品质的影响

以11个软米品系和一个粳米品种作为原料生产方便米饭,通过对软米的主要成分、蒸煮特性和复水性质的测定与分析,探讨方便米饭品质与大米主要成分、蒸煮特性、复水性质之间的关系。结果表明,原料大米中直链淀粉含量对蒸煮特性和复水性质的影响比较显著,原料米的蒸煮品质对方便米饭品质也有较大影响,软米较适于制作方便米饭,通过对比筛选出其中的R3和R2品系所生产的方便米饭品质优势较为突出,更加适宜作为生产方便米饭的原料。     

市售挤压方便米饭品质评价

为探究市售挤压方便米饭的主要品质评价指标,对国内市场畅销品牌的挤压方便米饭进行品质评价。选取19种市场畅销的挤压方便米饭产品,探究不同品类的方便米饭品质主要指标之间的差异性和相关性,并利用主成分分析对挤压方便米饭产品品质的评价指标进行筛选,通过系统聚类分析对挤压方便米饭产品进行分类。与其他类型的方便米饭以及新鲜米饭进行对比,验证挤压方便米饭品质评价的可行性。结果表明,不同品牌的挤压方便米饭主要的复水特性指标以及质构品质指标差异较大。挤压方便米饭的硬度和胶黏性与复水时间呈极显著正相关(P＜0.01),与适口性、滋味和冷饭质地及感官评分呈显著负相关(P<0.05)。主成分分析提取的3个主成分累计贡献率达到了81.24%,其中PC1(38.97%)主要包括了复水时间、感官评分、硬度、胶黏性和回复性。以综合得分为变量将19种样品分为3类,对比其他类型方便米饭和新鲜米饭的品质关联性指标,发现综合得分及感官评分高的样品,复水时间较长,硬度和胶黏性也较大,其指标特征更接近于粳米新鲜米饭,小于籼米新鲜米饭,胶黏性大于传统α化方便米饭和冻干方便米饭,硬度大于传统α化方便米饭,但略小于冻干米饭。因此,复水特性指标中的复水时间以及质构特性指标中的硬度和胶黏性可作为挤压方便米饭品质评价的关键指标。     

发芽糙米重组米制备方便米饭的研究

研究双螺杆挤压对发芽糙米重组米复水性能、营养成分及糊化特性的影响,随后以发芽糙米重组米为原料制备方便米饭,研究蒸煮和干燥工序对发芽糙米重组米方便米饭食用品质的影响。结果表明:螺杆转速120 r/min,三、四区挤压温度120℃、物料含水量20%时,发芽糙米重组米复水率最高,且糊化特性优于发芽糙米;相比于发芽糙米,发芽糙米重组米总淀粉、直链淀粉和可溶性蛋白含量下降,总蛋白、粗脂肪、纤维素和γ-氨基丁酸含量几乎不变。米水比1∶1.3、蒸煮30 min时,方便米饭的感官评分最高,且硬度和黏着性适中;蒸煮方便米饭经560 W-60℃微波热风组合干燥速度最快,此时得到的干燥方便米饭复水时间最短,复水率和碘蓝值最高。发芽糙米和发芽糙米重组米制备的方便米饭色泽和香味都较好,但发芽糙米重组米方便米饭的形态、口感和滋味更好。     

不同冻干工艺对冻干米线复水品质的影响

近年来,干制方便米线作为一种方便食品发展迅速,但是干制方便米线存在复水时间长、易糊汤、易断条、口感不理想、质构特性较差等问题。为了改善干制方便米线的这些特性,本研究采用?10、?20和?40 ℃ 三种冻结温度对米线进行真空冷冻干燥,分别得到三种冻干米线FDRN10、FDRN20、FDRN40样品,通过分析冻干米线在不同水温下的复水速度、微观结构、淀粉回生程度和质构特性的变化,探讨了冻结温度对冻干米线复水品质的影响。结果表明,在相同水温下经相同浸泡时间复水处理后,FDRN10含水量最高,表明其复水速度最快。外表面和横断面微观结构观察发现,三种冻干米线样品中FDRN10结构最为疏松,孔隙最大,为72.58 μm,是孔隙最小的FDRN40的4倍,结构吸水性最好。进一步的DSC检测发现FDRN10焓值最高,为92.98 J/g,焓值最低的FDRN40为12.39 J/g,表明FDRN10在三种冻干米线样品中回生程度最高,淀粉吸水溶胀最慢。同时硬度分析结果表明,在相同浸泡时间下FDRN10硬度值随水温的升高而降低,采用70 ℃热水复水8 min,FDRN10质构特性最接近鲜湿米线。以上结果表明,冻结温度和复水温度对冻干米线品质形成起到关键作用,本研究结果可为方便米线工艺改进提供理论依据。     

云南软米及其热风干燥方便米饭的食用品质

以云南软米为原料,并选择普通籼米、粳米、籼型糯米与之进行对比,量化分析了4种米饭的蒸煮品质和冷饭质地,并将云南软米应用于方便米饭的生产中。结果表明,软米米饭的综合感官品质优于其他3种米饭,软米的蒸煮特性与普通籼米及粳米有着较大区别。在4℃下放置24 h,软米米饭的硬度增加和黏度下降速度显著低于粳米和籼米米饭,即冷饭回生程度远低于二者。对最优工艺条件下制得的软米方便米饭与市售的粳米方便米饭相比较,其复水性优于市售的粳米方便米饭。体外消化研究表明软米方便米饭和市售粳米方便米饭的水解速率模式相似,且二者的血糖指数(GI)均在90以上,属于高血糖食品。     

冻干方便米饭品质评价方法及原料适应性的研究

本试验选取了10个品种的大米制作冻干方便米饭，测定了大米的直链淀粉含量和蛋白质含量，并且分析了这两项指标与感官指标以及物性指标（Texture Profile Analysis，TPA）与感官指标的相关关系。研究发现感官指标中的口感与大米的直链淀粉含量呈极显著的负相关，与TPA实验的Hardness和Adhesiveness两项指标呈极显著的负相关。结果表明大米的直链淀粉含量对冻干方便米饭品质有着显著的影响，利用TPA实验可以替代感观评价对冻干方便米饭的品质进行评价，其中利用直链淀粉含量相对较低的粳米制作的冻干方便米饭的口感较好。     

高抗性淀粉大米对方便米饭品质及GI值的影响研究

以高RS大米和市场普通大米为原料,研究不同添加量的高RS大米对方便米饭质构特性、感官评分、GI值的影响。通过质构特征分析和差示扫描量热仪测定在不同贮存时下,不同添加量的高RS大米对方便米饭淀粉抗回生效果的影响。结果显示,高RS大米添加量的增加,提高了方便米饭硬度、粘性和咀嚼性,增加了方便米饭的直链淀粉和抗性淀粉含量,同时降低了方便米饭的感官评分和GI值。此外,随着贮存时间的增加,高RS大米的添加量越高,方便米饭的硬度、相对结晶度、回生焓也越高。为方便米饭产品开发与大米精深加工提供依据。     

预处理和干燥方式对方便米饭品质的影响

研究不同蒸煮方式、干燥方式和预处理方式对方便米饭质构、体外消化率、血糖指数等因素的影响。实验结果表明,电饭锅蒸煮制备的方便米饭硬度和黏度要高于常规制备的方便米饭。-20℃冷冻+80℃热风干燥和4℃水洗+-20℃冷冻干燥方式制备的方便米饭品质最接近新鲜米饭。热风干燥方便米饭的复水率为2. 71,复水时间为8 min;冷冻干燥方便米饭的复水率为3. 32,复水时间为5 min。2种干燥方式制备的方便米饭体外消化率均高于新鲜制备的米饭,其饱和浓度C∞、水解指数HI和血糖指数GI等指标也相应的增高。感官评价结果表明,2种干燥方式制备的方便米饭均具有较好的品质,口感良好;其中,4℃水洗+-20℃冷冻干燥制备的方便米饭感官评价更高。     

挤压法制备营养方便米的品质

对挤压工艺制备的方便米和传统工艺生产的商用方便米食用品质对比结果表明．挤压工艺制备的方便米颜色浅白，透明度较低，糊化度高，表观密度较小，复水率稍高；传统工艺生产的商用方便米颜色较白，呈半透明，糊化度低，表观密度较大，复水率稍低．对复水后方便米饭的质构分析和感官评价表明，挤压工艺生产的方便米食用品质，除色泽外，均优于传统工艺生产的商用方便米，其品质接近杂交籼米新鲜米饭．通过强化大豆蛋白、VB1、VA，挤压工艺制备的方便米的营养效价得到提高．     

新型方便米食用品质的研究

本文以大米粉作为主原料，复配食品添加剂，采用挤压技术生产“工程重组米”的新思路，完全克服传统工艺对大米进行表面处理的局限性，试图为制备具有良好品质的方便米另辟蹊径。本文研究了挤压工艺和传统工艺制备的方便米以及商用产品的食用品质。挤压工艺制备的方便米颜色浅白、不透明，糊化度高、表观密度较小、复水率稍高。传统工艺制备的方便米颜色较白、呈半透明，糊化度低、表观密度较大、复水率稍低。通过对复水后方便米饭的质构分析和感官评价发现，挤压工艺生产的方便米食用品质，除色泽外，均优于传统工艺制备的方便米食用品质，其品质接近杂交籼米新鲜米饭。     

Effects of cooking, drying and pretreatment methods on texture and starch digestibility of instant rice

Instant rice produced from a conventional process consisting of the cooking, washing and drying steps possesses poorer eating quality compared with that of freshly cooked rice. The objective of this work was therefore to study the effects of cooking, pretreatment and drying methods on microstructure, textural properties and starch digestability of instant rice after rehydration; jasmine white rice was chosen as a test material. Conventional boiling method and electric rice cooking were selected as the methods to prepare cooked rice. In the case of boiling, cooked rice was frozen at −20 °C or cooled at 4 °C for 24 h prior to drying, while the cooked rice from an electric rice cooker was washed with ambient or cool water for 30 s prior to drying. After pretreatment the cooked rice was dried either by freeze drying or hot air drying at 80 °C. Based on the scanning electron microscopic results it was found that the cooking, pretreatment and drying methods all affected the rice morphology. The hardness and stickiness of instant rice after rehydration were lower for samples prepared from the rice cooker than those of freshly cooked rice, while both textural properties appeared to be improved significantly for the samples from boiling. The texture of the freeze-dried products was not different from that of the air-dried one. The freezing pretreatment provided the texture and glycemic index of instant rice after rehydration similar to those of the freshly cooked rice. On the other hand, the cooling pretreatment resulted in the harder texture and higher glycemic index of the samples.     

球磨微细化研磨对发芽糙米粉物性特征的影响

本文以发芽糙米为原料,利用扫描电子显微镜（SEM）、傅里叶红外光谱（FTIR）等手段探究了微细化研磨处理对发芽糙米粉干燥前后微粒粒径、微观形貌特征、水合性能、蛋白二级结构特征的影响。结果表明,经球磨处理后,发芽糙米粉的粒径明显降低,淀粉颗粒形貌与晶体结构遭到破坏,部分微粒外壳坍塌,喷雾干燥后颗粒变得细小且均匀,小颗粒的团聚现象减少;球磨处理2 h和喷雾干燥处理后,总的水合性能显著增强;蛋白质结构更为伸展,受剪切力影响,淀粉有序结构遭到破坏。球磨研磨发芽糙米粉粒径微细且分布均匀,颜色更白,具有良好溶解性、分散性和口感,并且经过冲调后形成了具备良好黏弹性的米浆,研究为球磨研磨处理全谷物提供基础数据与参考。     

Effect of heating condition and starch concentration on the structure and properties of freeze-dried rice starch paste

The structure and characteristics of freeze dried rice starch paste were investigated at low starch concentrations (1%, 3% and 5%). The microstructure of samples made at 1% of starch concentration showed a loose filamentous network compared to other concentrations (3% and 5%). Especially the samples prepared at processing conditions above 110 °C and 3% were appeared a coarse honeycomb-like structure. Crystallinity of samples calculated by intensities of X-ray diffraction peaks was very low values (3.3–9.8%). The mechanical properties (hardness, cohesiveness and springiness) of the samples were highly influenced by starch concentration and heating temperature. The relative increment of water absorption index (WAI) according to increasing of heating temperature showed the highest value at 1% of starch concentration, and the heating temperature was analyzed to the important factor affecting WAI and WSI (water solubility index). The digestibility of samples showed an increasing trend with heating temperature regardless of starch concentration. Overall, the important factors influencing the properties of freeze dried rice starch paste were starch concentration and heating temperature.     

方便米饭的老化机理研究

本文对方便米饭的老化机理进行了研究，方便米饭的老化主要是由淀粉的起始玻璃化温度升高和淀粉的部结结晶两方面引起。其中热特性变化为老化的主要因素。干燥过程的水分移动促进了淀粉晶体的形成。在存放过程中方便米饭的玻璃化温度会进一步上升，硬度增大，结晶度也稍有增加。文中提出了淀粉的“两区域”老化模型。蒸煮过程使淀粉部分分级，形成淀粉在有限水分下以支链淀粉为主的粘弹区和以直链淀粉为主的粘流区，两区域的形成促进了方便米饭的老化。     

扫描电镜在方便稀饭研制中的应用

方便稀饭的口感在很大程度上取决于成品的复水性，而成品的复水性与方便稀饭米粒内部淀粉结构密切相关。透彻了解淀粉结构从而对稀饭米粒组织结构进行有效修饰是生产可接受方便稀饭的基本前提，对改善食品品质具有极其重要的意义。本文采用扫描电子显微镜对方便稀饭加工过程中米粒的结构变化进行了观察，从理论方面对方便稀饭的复水性及口感问题作出了较合理的解释。     

Effect of starch and non-starch components on water migration,microstructure, starch retrogradation and texture of flat rice noodles made from different rice varieties

Effects of starch and non-starch components on rice noodle quality, water migration during rehydration, texture, microstructure and starch retrogradation of dried rice flour and rice starch noodles made from five rice varieties with similar high amylose contents were examined. Rice noodle qualities depended mainly on starch properties and to a lesser extent on the presence of non-starch components. Elongation of rice flour noodles was lower than rice starch noodles due to the presence of non-starch components that interrupted the starch network. Non-starch components reduced cooking loss of flour noodles in some varieties. Water migration in rice flour noodles with a looser microstructure was faster than in rice starch noodles. Nuclear magnetic resonance imaging revealed different water migration speeds in rice flour noodles among varieties, related to noodle microstructure and retrogradation properties. For production of good quality rice noodles, manufacturers should consider not only amylose content but also non-starch components.     

热风干燥型方便米饭品质评价方法及原料适应性

选用12个品种的大米制作热风干燥型方便米饭,分析了原料大米的成分、米饭蒸煮品质指标,以及物性指标(Texture Profile Analysis,TPA)与方便米饭感官指标之间的关系。结果表明,物性指标中的硬度与总分、滋味、形态呈显著的负相关性;黏着性与总分、口感呈显著的负相关性,与滋味呈极显著负相关;蛋白质含量与方便米饭的滋味、总分呈显著性负相关,与口感呈极显著负相关;直链淀粉含量与方便米饭的滋味、口感呈极显著负相关,与总分呈显著负相关。利用TPA试验可以辅助感官评价试验对感官品质进行评价,大米的直链淀粉含量和蛋白质含量对热干方便米饭滋味、口感、总分有显著的影响,选用直链淀粉含量较低和蛋白质含量较低的粳米制作的热干方便米饭其食用品质较好。