脂肪酸对大米淀粉热特性及质构品质影响的研究

为了解脂肪酸加入大米淀粉后对淀粉的热特性及质构品质的影响,以桂朝大米为原料,用加热糊化的办法将硬脂酸和油酸两种脂肪酸与其复合,制成大米淀粉——脂质复合物,研究不同脂肪酸添加量对大米淀粉的热性质和质构品质的影响。通过DSC和质构仪发现:脂肪酸的添加使淀粉的糊化温度降低,弹性和咀嚼度值变大,硬度和黏附性值减小,改善了大米淀粉的热性质和质构品质;且当添加量为4%时,效果最佳。     

鲜湿米粉品质评价及原料选择

为确定适宜鲜湿米粉加工用大米的关联性指标及阈值区间,本研究以18种大米为原料制备切条型鲜湿米粉,探讨大米主要成分质量分数、淀粉糊化特性对米粉蒸煮品质、入味性、感官品质和质构品质的影响,并利用主成分分析建立鲜湿米粉综合品质评价模型,计算米粉品质综合得分,通过逐步回归分析筛选出影响米粉综合品质的关联性指标,结合聚类分析得到适宜加工米粉的原料大米关联性指标范围。结果表明:大米的直链淀粉质量分数,淀粉糊化特性的最低黏度、最终黏度、衰减值、回生值与米粉的蒸煮品质、感官品质、质构品质显著相关(P0.05);大米主要成分、淀粉糊化特性与米粉的入味性相关性不显著(P0.05)。影响米粉综合品质的关联性指标为直链淀粉质量分数和最终黏度,适宜加工切条型鲜湿米粉的原料大米直链淀粉质量分数应大于26%,淀粉的最终黏度应大于3 852 Pa·s。     

大米基本成分与米发糕品质间相关性探讨

对10种大米的基本成分及其所加工成的米发糕品质进行分析,并对大米基本成分与米发糕的感官品质、质构特性之间相关性进行探讨。结果表明:影响米发糕品质的主要因素是大米直链淀粉含量、蛋白质含量、水分含量,其中直链淀粉含量对米发糕品质的影响最大;大米的直链淀粉含量与米发糕的比容、结构、回复性呈极显著正相关,与米发糕的外观形状、硬度、咀嚼性呈显著正相关;大米的蛋白质含量与米发糕的外观形状、硬度和咀嚼性呈显著负相关;大米的水分含量与米发糕的弹性呈显著负相关。     

压榨型鲜湿米粉条凝胶质构特性及食用品质影响因素

以压榨型鲜湿米粉条凝胶品质影响因素为研究对象,主要探讨了大米粉基本理化指标、快速黏度分析(rapid visco analyze,RVA)糊化特性、大米淀粉结晶特性对压榨型鲜湿米粉条的食用品质及其凝胶质构特性的影响。研究表明大米粉直链淀粉的质量分数与米粉条的感官得分、质构特性指标(除黏附性、弹性外)呈显著或极显著正相关(P0.05,P0.01),大米粉支链淀粉质量分数与米粉条感官得分、质构特性指标(除黏附性、弹性外)呈显著或极显著负相关(P0.05,P0.01);大米粉粗蛋白(除与恢复性呈显著正相关外)、粗脂肪质量分数与米粉条凝胶特性和食用品质相关性不显著(P0.05);X射线衍射、傅里叶变换红外光谱2种方法分析得到的结晶度RX和RI均与米粉条的凝胶特性指标和食用品质感官得分均无显著相关性(P0.05)。RVA糊化特性参数中的峰值黏度、最低黏度和最终黏度与米粉条的感官得分、质构特性指标(除黏附性、弹性外)呈显著或极显著正相关性(P0.05,P0.01);衰减值虽与感官得分、凝胶质构特性指标(除与黏附性显著负相关外)均呈一定的负相关性,但均不显著(P0.05);而回生值则与米粉条感官得分、凝胶质构特性指标的硬度、胶着性、咀嚼性、恢复性均呈极显著正相关(P0.01)。由此可见,直链淀粉、支链淀粉质量分数及RVA糊化特性参数可用来预测压榨型鲜湿米粉条的食用品质关键性指标。     

大米贮藏过程中理化性质及食味品质的变化

大米是人类主要的粮食作物之一,含有丰富的营养物质,是人体主要的热量来源。但大米在储存过程中易发生陈化和变质,影响大米的营养及食味品质。而大米的陈化、变质及食味品质下降与储藏过程中大米的理化性质的改变是密不可分的。将大米密封贮存于阴凉干燥的室温条件下,定期测定不同贮藏时间大米水分和直链淀粉含量、糊化性质、碱消值、膨润力和溶解度以及米饭质构特性等理化指标。结果表明:随着贮藏时间的延长,大米中的水分和直链淀粉含量、糊化温度、膨润力和溶解度以及回生值都呈现增长趋势;而大米的碱消值、糊化冷却过程中的黏度(峰值黏度、最低黏度、最终黏度)和崩解值呈现下降趋势;其蒸煮得到的米饭硬度上升,黏力和弹性均呈下降趋势,食用品质逐渐下降。     

湿热处理对大米淀粉理化性质及其米线品质的影响

以大米淀粉为原料,研究湿热处理对大米淀粉理化性质以及米线品质的影响。结果表明:与未处理大米淀粉相比,湿热处理后,大米淀粉的热学特性中T_0、T_P、T_C、T_C_T0、ΔH均增大;淀粉晶型仍为A型,结晶度增加4.14%;淀粉溶解率和膨润力显著降低,直链淀粉含量显著升高;淀粉糊化黏度、衰减值和回生值明显降低;淀粉凝胶硬度、弹性和耐咀嚼性增强;淀粉白度由89.7降低至80.3;添加20%湿热处理大米淀粉制作的米线感官品质和质构特性得到显著改善,断条率和蒸煮损失率分别降低5.67%,10.13%;大米淀粉溶解率、膨润力、溶解率、凝胶特性和糊化特性可有效预测米线品质。     

大米粉、大米淀粉及其磷酸酯淀粉的物性特征研究

利用快速黏度分析仪和质构仪测定了大米粉、大米淀粉及其磷酸酯淀粉的黏滞特性和质构特性,并用动态流变仪测定了大米粉、大米淀粉和磷酸酯淀粉糊的凝胶和回生。结果显示:磷酸酯淀粉的糊化温度显著低于大米粉和大米淀粉的糊化温度;磷酸酯淀粉抗老化性最强,不易回生,大米粉抗老化性最弱,易回生。大米淀粉经过磷酸酯化变性后,峰值黏度、崩解值和最终黏度增加,硬度、黏附性、弹性、胶黏性显著降低,凝聚性增强。在降温冷却过程中,大米粉的储存模量比大米淀粉和磷酸酯淀粉的储存模量增长速度快,大米粉和大米淀粉的损失因数降低,磷酸酯淀粉的损失因数升高。     

储藏后对不同加工精度大米食用品质变化规律的研究

选用新收获的粳稻为原料,用试验室碾米机对脱壳糙米碾磨一次,将大米置于室温和4℃条件下储藏6个月。为研究储藏期间大米内部食用品质的变化,对不同贮藏温度下的大米的直链淀粉、脂肪酸值、米饭硬度、和食味值等指标进行测定。结果表明:贮藏过程中,大米的直链淀粉含量和食味值降低,脂肪酸值以及米饭硬度增加,米饭黏度和弹性降低。贮藏温度越高,品质变化越明显。直链淀粉和脂肪酸值对大米的质构品质有显著性影响。大米随着储藏时间的延长其内部食用品质发生了显著变化,低温4℃储藏可在一定程度上延缓大米品质的变化。     

压榨型干米粉专用米关键指标的研究

为确定压榨型干米粉专用米的特征指标,文章以17种籼米为原料,运用相关分析、主成分分析、聚类分析以及逐步回归分析法探讨大米原料品质和糊化特性对干米粉食用品质和质构品质的影响。结果表明:大米原料中的直链淀粉含量、淀粉含量、脂肪含量、脂肪酸值,糊化特性中的最低黏度、最终黏度、崩解值、回生值、胶稠度,与干米粉的蒸煮品质和质构品质存在显著(P<0.05)相关性;其中影响米粉综合品质的关键性指标为直链淀粉含量、最终黏度和胶稠度;聚类分析得出的适宜加工压榨型干米粉的原料大米的直链淀粉含量应大于22%,淀粉的最终黏度应大于3963 cP,胶稠度应小于46 mm。     

不同品种大米理化性质及其淀粉结构对米饭食用品质的影响

米饭食味值和质构特性是评价大米食用品质的重要指标,为了探究不同品种大米的食味值、质构特性与其理化性质及淀粉结构的关系,以12种大米为研究样本,测定其食味值、质构特性、理化性质及淀粉结构特性,并分析内在相关性。结果表明,直链淀粉含量（质量分数）与米饭的硬度呈极显著正相关（P<0.01）,与米饭的凝聚性呈极显著负相关（P<0.01）;米饭食味值、质构特性与大米淀粉的糊化特性、热特性之间存在显著相关性,与结晶特性、淀粉颗粒表面有序度无显著相关性,表明淀粉的糊化特性决定了米饭的食味值、硬度、凝聚性和回复性。该研究可为后期优质稻米筛选培育以及大米适宜性加工提供理论基础。     

三种天然植物淀粉辅料对米粉丝品质特性的影响

以天然绿豆淀粉、玉米淀粉及马铃薯淀粉3种天然植物淀粉为原料,探讨其作为辅料添加对米粉丝蒸煮品质和质构特性的影响。结果表明,添加适量的绿豆淀粉、玉米淀粉或马铃薯淀粉可显著提高米粉丝的烹煮品质及质构特性。绿豆淀粉添加量在0.5~1.5%时加工的米粉丝具有较高的烹煮品质,其添加量在1%时可以显著提高米粉丝的质构特性;玉米淀粉的添加量为6%时米粉丝的烹煮品质较佳,其添加量在4~6%时可显著提高米粉丝的质构特性;马铃薯淀粉的添加量为2%时,米粉丝具有最高的烹煮品质,其添加量在2~3%时可使米粉丝的质构特性显著提高。综合考虑,当绿豆淀粉、玉米淀粉或马铃薯淀粉的添加量分别达到1%、6%和2%时能够显著改善米粉丝的蒸煮和质构品质特性。     

Effect of Raw Material Preparation on Rice Vermicelli Quality

The physicochemical properties of high amylose rice flour prepared from wet milling and dry milling were examined and the rice vermicelli quality made from these flour samples was evaluated. The effect of flour particle size on rice vermicelli quality was also determined. The milling method affected chemical compositions and all physicochemical properties of the flour. A higher degree of starch damage occurred in drymilled flour. Rice vermicelli made from dry‐milled flour had higher cooking losses and softer texture than that made from wet‐milled flour and the commercial reference products. Flour particle size influenced both cooking and textural quality of rice vermicelli but did not influence the water absorption index. Flours with larger particle sizes gave vermicelli with higher cooking loss and less desirable texture than flours with smaller particle sizes. Flour with particle sizes less than 200 mesh produced acceptable vermicelli in terms of cooking and textural quality.     

复配粉理化性质与米线质构性质关系的研究

将粳米粉与绿豆淀粉按照一定比例进行混合,得到粳米粉和绿豆淀粉的复配粉体系,并测定了复配粉体系的溶胀性质、糊化性质、凝胶质构性质和拉伸性质,研究了复配米粉体系的拉伸性质与米线质构性质的关系。结果表明:随着绿豆淀粉添加量比例的增加,复配米粉体系的总直链淀粉含量、可溶性直链淀粉含量和不溶性直链淀粉含量明显增加,峰值黏度、谷值黏度、末值黏度、硬度也显著性增加,咀嚼性、拉伸强度和表观弹性模量显著增加,85℃下的溶解度和膨润力显著上升;糊化温度显著降低;衰减值和回生值分别比粳米粉高了33.73 RVU和50.60 RVU;与单一体系相比,由复配粉体系制成的米线呈现较好的硬度、弹性、韧性、蒸煮性和物理性质。当绿豆淀粉∶粳米粉为1∶1时,其制得的米粉的质构性质最好。     

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.     

Mechanisms of objectionable textural changes by microwave reheating of foods: a review

Microwave reheating, compared to a conventional method, is notorious for lack of crust formation and severe toughening of flour and starch-based products. This review discusses how the typical thermal characteristics of microwave heating are involved in affecting the texture as well as the possible role of non-thermal effects. While low surface temperature is the well known mechanism why microwave heating is incapable of crust formation, the most severe toughening problems are caused by internal boiling. Beside moisture loss, the internally generated steam causes 2 main textural effects when it is vented out. The first is the replacing of non-condensable gases (air) in the product voids with a condensable one (steam). When the latter is condensed by cooling, a vacuum may be created in the voids causing their collapse and a formation of a more compact and tougher structure. The second textural effect involves amylose extraction from starch granules and its redistribution to eventually form a rich layer on the walls of the structural foam cells of the baked goods. Relatively fast crystallization of the amylose seems to be the main cause of toughening a short while after microwave heating. This mechanism is relevant mainly to products where starch is an important structural element. Structural disruptions by localize excessive steam pressure at hot-spots are also discussed in this review as well as methods of preventing or alleviating the most objectionable textural changes. The most effective ways of preventing these undesirable changes are by avoiding internal boiling and/or by manipulating the starch content and properties.     

Gel texture and rheological properties of normal amylose and waxy potato starch blends with rice starches differing in amylose content

This study characterised the textural and rheological behaviour of blends of rice (waxy, low- and high-amylose) and potato (waxy and normal) starch. Blends of potato starch with rice starch in the ratios of 100:0, 80:20, 60:40, 40:60, 20:80 and 0:100 were tested. Addition of rice starch (except high-amylose rice starch) greatly increased the swelling of rice–potato starch mixtures. Addition of rice starch decreased gel firmness for most starch mixtures and increased gel adhesiveness for blends containing waxy potato starch. For rheological measurements, storage modulus was much higher than loss modulus of blends, indicating solid-like behaviour. Starch blends with 20%/40% proportion of rice starch showed a greater thickening effect, whereas with further increase in rice starch proportion, a pseudoplastic, shear-thinning behaviour was observed. This study may provide a basis to develop blends of potato and rice starch for potato noodle production without use of chemical additives.     

Effects of freezing rates on starch retrogradation and textural properties of cooked rice during storage

The effects of freezing rates and storage temperatures on starch retrogradation and textural properties of cooked rice were evaluated. Cooked rice was frozen with different freezing rates and then stored at 4 °C for 14 days or −18 °C for up to 7 months. Starch retrogradation enthalpy (ΔH_r) of cooked rice was determined by a differential scanning calorimetry, and textural properties were determined by a texture analyser. The results showed that the ΔH_r and hardness values had a negative correlation with freezing rate, however, a positive correlation was found between adhesiveness and freezing rate. On the other hand, the advantages (lower hardness and higher adhesiveness, less starch retrogradaton) of cooked rice gained by rapid freezing, were lost quickly in the first 3 days of storage at 4 °C. However, rapid freezing combined with −18 °C frozen storage can effectively retard starch retrogradation and maintain the textural properties of cooked rice for at least 7 months. Therefore, high quality cooked rice can be produced by combined rapid freezing with frozen storage.     

微生物强化发酵对米粉品质的影响

研究目的及方法：采用接种植物乳杆菌（L.p-35）、发酵乳杆菌（L.f-7）、热带假丝酵母（C.t-3）、枯草芽孢杆菌（B.s-14）进行强化发酵制作米粉,通过测定发酵后大米及米粉的蛋白、淀粉、直链淀粉含量,采用扫描电镜观察发酵对大米籽粒外观结构的影响,并从米粉产品质构、感官品质两方面,对比研究了强化发酵与传统自然发酵的差别。结果：强化接种L.p-35+L.f-7+C.t-3+B.s-14（第4组）四种微生物发酵制得的米粉与其他强化发酵组相比,蛋白含量明显降低,淀粉、直链淀粉含量明显增加。通过扫描电镜观察,强化发酵组明显改变了大米颗粒表面结构。结合质构及感官评定,第4组及自然发酵组制得的米粉品质在弹性、咀嚼性、爽滑感等方面优于其他强化发酵组。结论：综合各方面评分,第4组在优化大米结构、提高米粉品质方面存在明显优势,并结合pH、微生物变化情况,强化发酵有利于加速发酵过程。为开发米粉发酵剂提供了理论支持。     

凉粉草胶与不同淀粉混合体系糊化和质构性质的研究

凉粉草胶(MBG)与淀粉作用可以形成凝胶。为比较不同淀粉与MBG混合体系糊化和凝胶性质的差异,选取玉米等八种常见淀粉,利用Brabender糊化仪、质构仪、对MBG与不同淀粉混合体系的糊化和质构性质进行了研究。结果发现,MBG对谷类淀粉(大米、小麦、玉米)和豆类淀粉(绿豆、豌豆)的糊化性质的影响都比较显著,对薯类淀粉(木薯、马铃薯、甘薯)的不显著,但MBG与薯类淀粉混合体系的黏度远高于MBG与豆类和谷类淀粉的;MBG与大米淀粉形成的凝胶硬度最大,与马铃薯淀粉形成的凝胶硬度次之,与豌豆淀粉形成的凝胶硬度最小。淀粉与MBG之间相互作用的强弱可以从Brabender糊化曲线上的特征点值E-D来比较。