Predicting Rice Physicochemical Properties Using Thickness Fraction Properties

Long‐grain rice cultivars Francis and Wells and hybrid XL8 Clearfield were harvested from two locations at three harvest moisture contents (HMC) in 2003. The rough rice was dried, fractionated into thin, medium, and thick fractions, and milled. Physicochemical properties of unfractionated and fractionated samples were determined. The effects of HMC and location on thickness distributions were investigated and the weighted‐average physicochemical properties of the thickness fractions were compared with those of unfractionated rice. Generally, the growing location and HMC affected kernel thickness distributions, green kernel content, fissured kernel content, and head rice yield (HRY). As kernel thickness within samples increased, amylose content increased and the protein content and α‐amylase activity decreased. Thick fractions had greater peak viscosities than medium and thin fractions. The thin, medium, and thick fraction physicochemical property weighted averages provided good predictions of most unfractionated rice sample properties. However, this approach was not entirely accurate for predicting HRY, milled rice total lipid content, and bulk density.     

Factors Affecting the Slope of Head Rice Yield vs. Degree of Milling

Milling data of four long-grain rice cultivars were analyzed to determine the uniformity in the slope of their curves for head rice yield (HRY) versus the corresponding degree of milling (DOM). The data set for each cultivar comprised samples that had been subjected to various drying air conditions and durations and milled over a range of moisture contents. All treatment combinations were split and milled for either 15, 30, 45, or 60 sec in a McGill no. 2 laboratory mill to obtain HRY versus DOM data. Linear relationships between HRY and DOM, as observed in past research, were confirmed. This implies that as rice is milled to greater extents (higher DOM), the HRY decreases linearly. Within the bounds of the experimental levels tested, neither the drying air condition nor drying duration affected the rate at which HRY changed with DOM. However, the cultivar and the moisture content at which the rice was milled significantly (P < 0.05) influenced this rate. At higher milling moisture contents, the decrease in HRY per unit of increase in the DOM was greater than at lower moisture contents. While not conclusive, there was an indication of a relationship between the average kernel thickness of a cultivar and the HRY versus DOM slope.     

钵苗摆栽籼粳杂交稻和常规粳稻丰产优质适宜施氮量分析

研究钵苗摆栽下籼粳杂交稻、常规粳稻丰产优质施氮量及综合效益,提出安徽沿江地区钵苗摆栽下适宜粳稻类型及施氮量。于2016—2017年连续2 a开展大田试验,以当地主栽籼粳杂交稻甬优1540和常规粳稻镇稻18为供试品种,设置0、195、255、315、375 kg/hm~2共5个氮肥水平(分别用N0、N195、N255、N315、N375表示),研究不同施氮水平对钵苗摆栽下不同类型粳稻产量、品质、相关农艺性状及经济效益的影响。结果表明,籼粳杂交稻甬优15402a均在N315处理下产量最高,达到10.30～11.55t/hm~2。常规粳稻镇稻18各施氮处理下水稻产量无显著差异,产量为7.43～8.91 t/hm~2。增施氮肥,不同程度增加了2个品种的糙米率、精米率和蛋白质含量,提高了加工品质和营养品质,但垩白率和垩白度整体有所提高,直链淀粉含量增高,不利于外观品质和食味的改善。甬优1540在N315处理下的整精米率与N375无差异,且在N315处理下的垩白度与N195无显著差异。另外,镇稻18在N195处理下的整精米率、蛋白质含量、垩白度和直链淀粉含量与其他氮肥处理无显著差异。钵苗摆栽下籼粳杂交稻丰产优质施氮量为315kg/hm~2,常规粳稻为195 kg/hm~2。在适氮水平下,钵苗摆栽甬优1540较镇稻18提高水稻产量22.9%～23.2%,整精米率2.15%～4.50%,蛋白质含量30.44%～37.41%,经济效益51.07%～53.33%,同时降低垩白度9.52%～13.73%。总的来说,在适宜氮肥水平下,钵苗摆栽下籼粳杂交稻较常规粳稻提高了水稻产量、品质和经济效益。     

四川杂交稻骨干恢复系稻米品质对氮素水平的响应

【目的】 氮素作为水稻生长发育的必需营养元素之一,显著影响稻米品质的形成。明确氮素水平对稻米品质的影响及不同品种对氮素的敏感性,可为水稻的优质育种和科学施肥提供依据。 【方法】 采用两因素裂区大田试验方法,主区为三个施氮水平 (N 0、90、180 kg/hm2),裂区为15个骨干恢复系和宜香优2115水稻材料。分析了稻米加工品质、外观品质和蒸煮食味品质,并采用聚类分析方法,调查了供试材料的氮素敏感性。 【结果】 1) 随氮素水平的提高,稻米精米率及长宽比变化较小,但稻米糙米率和整精米率显著提高,与N0处理相比,N90与N180处理下稻米糙米率分别提高0.8%、1.4%;整精米率分别提高5.7%、7.9%;垩白度和垩白粒率则显著降低,与N0处理相比,N90与N180处理下稻米垩白度分别降低26.1%、55.0%;垩白粒率分别降低12.6%、32.8%。2) 氮素水平显著影响稻米淀粉RVA谱特征指标。随施氮量提高,稻米峰值粘度、热浆粘度、冷胶黏度、回复值及直链淀粉含量明显降低,消减值、崩解值、糊化温度及峰值时间变化较小。3) 聚类分析表明,施氮水平影响着水稻恢复系对氮素的敏感性。N90水平下,低氮敏感型包括乐恢188、成恢727及沪恢602;低氮中间型包括绵恢725、沪恢17、绵恢523及西科恢768;低氮迟钝型包括明恢63、多恢1号、成恢838(718、3023)、雅恢2115、蜀恢498(527)、宜香优2115。N180水平下,氮敏感型包括乐恢188、绵恢725、沪恢17、西科恢768;氮中间型包括明恢63、多恢1号、蜀恢498(527) 及宜香优2115;氮迟钝型由雅恢2115、成恢3203(838、718、727)、绵恢523及沪恢602组成。 【结论】 提高氮素水平可有效改善四川省骨干恢复系稻米的加工和外观品质,调节稻米淀粉RVA谱特性。其中雅恢2115、成恢3203(838、727、718) 及沪恢602品质较高且随氮素变化较小,属于氮迟钝品系,此类品系在低氮条件下品质属性变化较小。乐恢188、绵恢725、沪恢17及西科恢768属于氮敏感品系,此类品系对氮敏感度高,品质受氮素影响较大。氮中间品系则包括明恢63、多恢1号、蜀恢498(527) 及宜香优2115。      

我国稻米整精米率特点及环境影响因素分析

为我国稻米整精米率的提高、品种品质的改善提供参考,本文对2002-2009年度全国稻米普查抽征的5574份稻谷样品的整精米率进行影响因素分析。结果表明,我国稻米整精米率年均值总体徘徊在55.0%,地域特点为北高南低;稻米整精米率与粒长、垩白粒率呈负相关性;地理位置、气候效益等环境因素对整精米率均有一定的影响。     

Effects of Nighttime Temperature During Kernel Development on Rice Physicochemical Properties

Rice quality can vary inexplicably from one lot to another and from year to year. One cause could be the variable temperatures experienced during the nighttime hours of rice kernel development. During the fall of 2004, a controlled temperature study was conducted using large growth chambers, testing nighttime temperatures of 18, 22, 26, and 30°C from 12 a.m. until 5 a.m. throughout kernel development, using rice cultivars Cypress, LaGrue, XP710, XL8, M204, and Bengal. As nighttime temperature increased, head rice yields (HRY) significantly decreased for all cultivars except Cypress and Bengal, for which HRY did not vary among nighttime temperature treatments. Kernel mass did not vary among temperature treatments for any cultivar. Grain dimensions generally decreased as nighttime temperature increased. The number of chalky kernels increased with an increase in nighttime temperature for all cultivars but Cypress. The amylose content of Cypress and LaGrue was significantly lower at the nighttime temperature of 30°C, while total brown rice lipid and protein contents did not vary among temperature treatments for all cultivars.     

Effect of Moisture Content at Harvest and Degree of Milling (Based on Surface Lipid Content) on the Texture Properties of Cooked Long-Grain Rice

The effects of the degree of milling (based on surface lipids content [SLC]) on cooked rice physicochemical properties were investigated. Head rice yield (HRY), protein, and SLC decreased with increasing milling, while the percent of bran removed and whiteness increased. Results showed that SLC significantly (P < 0.05) affected milled as well as cooked rice properties across cultivar, moisture content (MC) at harvest, and location (Stuttgart, AR, and Essex, MO). Cooked rice firmness ranged from 90.12 to 111.26 N after milling to various degrees (SLC). The decrease in cooked rice firmness with increasing milling was attributed to the lowering of total proteins and SLC. Cooked rice water uptake increased with increasing degree of milling. Water uptake by the kernel during cooking dictated the cooked rice firmness. The increase in cooked rice stickiness with increasing degree of milling was attributed to an increase in starch leaching during cooking because of the greater starch granule swelling associated with a greater water uptake.     

Effect of Milling Temperature and Postmilling Cooling Procedures on Rice Milling Quality Appraisals

The objective of this research was to study the effects of different milling conditions and postmilling handling procedures on appraised milling quality of rough rice. Rough rice (M202) with moisture content of 11.5 ± 0.2% was used for this study. The samples were milled with a McGill number 3 mill under four milling conditions, including normal milling, milling at high temperature, milling with cooling using ice water, and room temperature water. The milled rice samples were cooled in closed and open plastic containers and in open pans with three temperatures: 15, 23, and 35°C. The effects of milling and postmilling conditions on milled rice temperature, moisture loss, cooling rate, single and multiple fissuring rates, total rice yield (TRY), head rice yield (HRY), whiteness index (WI), and total lipid content (TLC) were evaluated. Results showed that high single and multiple fissuring rates and low TRY and HRY were inherent in improper milling and postmilling conditions. Single fissuring rates were 15.9 and 17.6% and multiple fissuring rates were 3.5 and 7.2% for rice samples milled under normal and high‐temperature conditions, respectively. Cooling methods that used open containers and pans had more moisture losses and further resulted in lowering appraised milling quality than methods that used closed containers. Low‐temperature milling conditions followed by cooling in closed containers significantly reduced single and multiple fissuring rates and improved TRY and HRY by 0.9 and 1.5 percentage points, respectively. The effects of tested milling and postmilling conditions on WI and TLC were not significant. Obtained results constitute valuable information for developing milling and cooling procedures to achieve consistent, accurate, and reliable milling quality appraisals for rough rice.     

氮量和施用方式对水稻“甬优6号”产量和品质的影响

以籼粳杂交水稻甬优6号为试材,于2006和2007年分别研究了施氮量和施用方式对其产量与品质的影响,以明确该品种在温州种植点适宜的施氮量及方式,达到高产与优质协调。结果表明,随施氮量递增,稻谷产量基本呈先升后降的趋势,以施N 139 kg/hm2时,采用以基肥:分蘖肥:促花肥:保花肥为6:2:1:1（处理II）的施肥方式产量最高。施氮处理稻米的糙米率、精米率、整精米率、垩白度、胶稠度、蛋白质及其谷蛋白等品质指标均明显高于不施氮处理,但施氮处理间差异不显著。随施氮量增加,峰值粘度、崩解值和回复值依次递减,消减值依次递增。不同施用方式处理峰值粘度差异显著;施氮量和施用方式处理间米饭的硬度和粘性均达显著差异水平。施用方式处理III的硬度与处理II差异不显著,但粘性显著高于后者。考虑产量和品质两因素,本试验中甬优6号在温州地区可以选择施N 139 kg/hm2,并采用基肥:分蘖肥:促花肥:保花肥为6:2:1:1的施用方式,以实现高产和优质。     

不同施氮水平下稻米品质对日间增温响应的差异

以武育粳3号为材料,设置低、中、高3个氮素穗肥处理,开放环境下使用加热器进行日间增温处理,研究灌浆结实期不同施氮水平下稻米品质对日间增温响应的差异。结果表明: 1）灌浆结实期日间增温使各氮肥处理精米率和整精米率下降,垩白粒率和垩白度增加,糙米率和子粒长宽比各氮肥处理变化不一,低氮和中氮处理糙米率和子粒长宽比减小,高氮处理则变大;加工品质和外观品质各指标变化幅度均以中氮处理最大,减少或增加氮肥施用量均可以有效地缓解高温对稻米加工品质和外观品质的负面效应,尤以增施氮肥效果较佳。2）增温条件下,减少和增加氮肥施用量均能降低稻米直链淀粉含量,其中增施氮肥降低幅度较大;增温后各氮肥处理蛋白含量均增加,增加幅度与施氮量呈负相关关系,高温高氮处理直链淀粉含量最低,蛋白含量最高。3）增温后各穗肥处理结实率和千粒重均下降,以中氮处理下降最显著;减少和增加穗氮施用量均能有效地缓解高温对水稻产量的影响,其中也以增施氮肥相对较好。综上所述,适当地增加氮肥施用量能较有效地缓解高温对稻米品质和产量的负面影响。     

氮肥运筹对免耕高留茬抛秧稻氮素吸收、运转和子粒品质的影响

田间裂区试验研究了氮肥运筹对免耕高留茬抛秧稻氮素吸收、运转和稻米品质的影响。结果表明,随施氮量增加,水稻吸氮增多,转移到穗部的比例下降、滞留在叶片中的比例增加,氮素干物质生产效率和产谷效率下降。增施氮肥提高了糙米率、精米率和整精米率,垩白米率、垩白度和蛋白质含量随施氮量增加而上升。随施氮量的增加,淀粉RVA谱特征的最高粘度和崩解值降低,消减值和糊化温度升高。基∶蘖∶穗肥比为7∶0∶3和4∶3∶3处理提高了氮素农艺效率、稻米蛋白质含量、消减值,降低了最高粘度。     

花后增温对双季优质稻产量和品质的影响

为明确未来气候变暖对双季优质稻产量和稻米品质的影响,采用开放式主动增温系统,早稻以金早47(常规籼稻)、两优287(杂交籼稻),晚稻以象牙香珍(常规籼稻)、万象优华占(杂交籼稻)和甬优5550(籼粳杂交稻)为试验材料,研究花后增温对双季优质稻产量和稻米品质的影响。结果表明,花后増温(早稻1.29℃,晚稻1.73℃)对早晚稻产量均无显著影响。增温条件下,早稻加工品质和垩白粒率均无显著变化,垩白度平均提高了16.0%;晚稻糙米率、整精米率、垩白粒率和垩白度分别平均提高了1.8%、3.5%、30.3%和27.2%;早晚稻蛋白质含量平均提高了6.27%,但直链淀粉含量平均降低了3.53%,淀粉颗粒的平均粒径提高了0.09 μm。增温对稻米RVA谱特征值的影响在季别和品种间存在较大变异。综上,花后增温对早晚稻产量无显著影响,有利于改善稻米的加工品质和营养品质,但降低了稻米的外观品质。本研究结果为未来气候变暖下双季优质稻的优质丰产栽培提供了理论依据。     

抽穗期高温胁迫对水稻产量构成要素和品质的影响

以扬稻6号与南粳43为试验材料,通过在人工气候箱中进行高温处理,研究抽穗期高温胁迫对水稻产量构成要素及稻米品质的影响,旨在深入探讨高温对水稻的伤害机理。研究表明:水稻抽穗期高温降低了水稻的每穗总粒数、结实率和千粒重,同时稻米的糙米率、精米率、整精米率、可溶性糖和蛋白质含量也呈下降趋势,而稻米的垩白率、垩白度和直链淀粉含量增加明显,随胁迫温度的提高和胁迫时间的延长,2个水稻品种的产量构成要素和稻米品质急剧下降。相同温度胁迫下,扬稻6号的热害指数(Index of heat sensitivity,HIS)稍低于南粳43,其中扬稻6号的产量构成要素和品质受高温的影响也稍低于南粳43,说明扬稻6号耐高温能力高于南粳43。研究结果为进一步了解高温对水稻结实和稻米品质的伤害机理,筛选耐热性强的水稻品种提供重要的理论依据。     

非浸泡复合酶法预处理改善糙米碾米性能

在糙米碾米过程中普遍存在碎米较多及碾米能耗高的问题,为改善糙米碾米品质,提出以纤维素酶和木聚糖酶的复合酶溶液处理替代常规水加湿方法的酶法预处理工艺。以贮藏期糙米(含水率15%以下)为原料,采用二次正交旋转中心组合设计试验,研究复合酶溶液处理工艺中复合酶配比、酶质量浓度、加液量及酶处理时间对碾米后整精米率和碾米能耗的影响规律,建立了各因素对整精米率和碾米能耗影响的数学模型。结果表明:构建的整精米率、碾米能耗与复合酶配比、酶质量浓度、加液量及酶处理时间之间的回归方程极显著(P0.01),得到优化参数组合为纤维素酶和木聚糖酶质量比1.3∶1 g/g、复合酶溶液质量浓度65 mg/m L、加液量1.25%,酶处理时间102 min,该条件下整精米率为80.07%、碾米能耗为90.72 k J/kg。复合酶溶液处理后整精米率较加湿调质处理提高约3.98%,节约能耗约13.06%;较纤维素单一酶溶液加湿处理后整精米率提高约0.98%,节约能耗约5.48%。并通过微观结构分析证实了糙米皮层粗纤维的局部破损是其碾米性能改善的主要原因。研究结果可为实际生产条件下的酶法糙米预处理工艺提供参考。     

氮锌互作对水稻产量及籽粒氮、锌含量的影响

为探明氮锌互作对水稻产量及氮、锌含量的影响,以镇稻11号为供试材料,在大田条件下研究了2个氮肥用量（N 200、300 kg/hm2）下6个施锌水平（ZnSO47H2O 0、10、25、50、100、150 kg/hm2） 对水稻产量及成熟期植株氮、锌浓度及累积量的影响。试验结果表明: 在本试验条件下,锌肥的施用对水稻产量的增加不显著,但施锌能显著提高水稻各部位的锌浓度和籽粒锌累积量,并能提高水稻籽粒的氮浓度和粗蛋白含量,且表现出随施锌量的增加籽粒的氮浓度和粗蛋白含量增加的趋势; 高施氮量有利于水稻的增产及对锌的吸收与累积。因此,氮锌配施具有增加籽粒锌富集和提高蛋白质含量的双重效益。     

氮肥运筹方式及催芽氮肥用量对再生稻产量及品质的影响

  【目的】  催芽肥和促苗肥的合理施用是保障再生稻高产优质的重要途径,明确再生稻氮肥运筹方式及催芽氮肥适宜用量,对提高再生稻产量和氮肥利用率、优化再生稻米品质具有重要意义。  【方法】  本研究采用多年田间试验,以深两优5814为材料,设置5个再生季氮肥 (N)处理:不施氮肥 (N_0-0);催芽肥60 kg/hm2 (N_60-0)、促苗肥60 kg/hm2 (N_0-60)、催芽肥和促苗肥各60 kg/hm2 (N_60-60)、催芽肥和促苗肥分别为120、60 kg/hm2 (N_120-60)。  【结果】  3年试验产量存在较大差异,但同一年份的再生稻施氮处理均显示了显著的增产效果,N_60-0、N_0-60和N_60-60处理分别较N_0-0平均增产35.8%、40.9%和67.4%。催芽肥和促苗肥配施通过提高有效穗数和每穗粒数进一步提高再生稻产量。随催芽氮肥用量的增加,产量呈先升高后平台的趋势。适宜的催芽氮肥用量和促苗肥配施促进了再生芽的萌发、形成和生长发育,显著增加了倒2节和倒3节 (尤其是倒3节)的有效穗数和每穗粒数。养分吸收积累研究结果显示,随着氮肥用量的增加,再生稻地上部氮素积累量显著提高。与N_0-0处理相比,N_60-0、N_0-60、N_60-60和N_120-60处理氮素积累量分别平均增加51.31%、57.70%、91.33%和124.53%,但氮肥利用率则呈下降的趋势。品质分析结果显示,随着氮肥用量的增加,再生稻米的加工品质、外观品质、直链淀粉含量先提升后下降,蛋白质含量则呈逐渐增加的趋势。催芽肥和促苗肥配施且用量适宜 (N_60-60)时,再生稻米的加工品质、外观品质等较其他处理为最优。与N_0-0处理相比,N_60-60处理的糙米率、精米率和整精米率分别增加2.7%、1.3%和6.7%;垩白度和垩白粒率分别降低13.8%和22.6%。而催芽氮肥用量进一步增加 (N_120-60)时,稻米的加工品质和外观品质又有所下降,以其整精米率下降、垩白粒率增加最为显著。  【结论】  本试验条件下,施用催芽肥和促苗肥各60 kg/hm2与不施氮相比显著提高了再生稻产量和稻米品质,其氮肥利用率较高。     

成都平原两熟区水氮管理模式与磷钾肥配施对杂交稻冈优725产量及品质的影响

以杂交稻冈优725为材料,通过淹水灌溉+氮肥优化运筹（W1N1）、 控制性交替灌溉+氮肥优化运筹（W2N1）、 旱种+氮肥优化运筹（W3N2）3 种水氮管理模式及不同的磷钾肥配施处理,研究其对成都平原两熟区水稻产量、 养分分配及品质的影响。结果表明,水氮管理模式和磷钾肥配施对稻米品质、 稻株各营养器官养分分配及产量均存在显著影响;水氮管理模式对稻谷产量、 整精米率、 直链淀粉、 蛋白质及RVA谱影响明显高于磷钾配施处理,而磷钾肥配施对垩白度、 垩白粒率、 胶稠度的调控作用显著。W2N1相对于W1N1及W3N2水氮管理模式的水稻产量分别提高3.02%和28.21%,为本试验最优的水氮管理模式,且与施磷量P2O5 90 kg/hm2、 施钾量K2O 90~180 kg/hm2 配施组合能进一步提高结实率和千粒重,利于成熟期籽粒氮、 磷、 钾素及稻株总养分累积量的增加,达到水肥耦合促产的目的,而且能提高整精米率、 胶稠度、 蛋白质含量,降低垩白度、 垩白粒率、 直链淀粉及消减值,改善米质。W1N1模式与P90K90配施为宜;旱种相对于淹灌下的水氮优化管理模式,不利于产量及米质的提高,但与P90K180配合对稻谷的产出及米质的改善有一定的补偿作用,可为生产中在水资源不足的情况下提供参考。     

香稻产量和品质对化肥施用及气候因素的响应

  【目的】  香稻因其独特的香味深受消费者喜爱,明确香稻产量和品质对化肥施用的响应及其与气候条件的关系,对综合提升香稻产量和品质具有重要意义。  【方法】  在中国知网、谷歌学术等数据库以关键词“水稻”、“香气”、“香味”以及“香稻”和“香米”及其组合进行文献检索,共获得501组试验数据对。将施肥与对照分为两组,采用整合分析方法(meta-analysis),分析了施用氮磷钾肥对香稻产量和品质的影响,以及在不同生育期累积降水量、积温和日照时数条件下的变化率。  【结果】  施用氮、磷、钾肥,香稻的平均增产率分别为23.7%、25.8%、18.0%。与不施用氮肥相比,施用氮肥对粳稻和籼稻增产率分别为27.6%和20.2%;与不施用钾肥相比,施用钾肥对粳稻和籼稻的增产率分别为29.9%和7.3%。施用氮肥可显著增加香稻碾磨品质(整精米率)和蒸煮品质(粗蛋白含量,胶稠度),施用钾肥可显著增加香稻碾磨品质(整精米率)、蒸煮品质(粗蛋白含量,胶稠度)、外观品质(垩白度)和香味品质(2-乙酰-1-吡咯啉含量,以下简称2-AP)。施用氮肥对籼型常规香稻的品质提升效果显著,而施用钾肥则对籼型杂交香稻的品质提升更显著。此外,施用氮肥下香稻整精米率的变化率随生育期内有效积温升高呈持续增加趋势,而随累积降水量和日照时数的增加呈先升后降趋势;胶稠度的变化率随气候变化(有效积温、降水量和日照时数等的增加)呈现先降后增趋势。施用钾肥下香稻整精米率的变化率随生育期内有效积温和日照时数升高呈现先降后增趋势,而随累积降水量的变化呈先升后降趋势;垩白粒率的变化率随气候变化均呈先降后增的趋势;胶稠度的变化率随气候变化(有效积温、降水量和日照时数等的增加)均呈降低的趋势。  【结论】  施用氮肥或钾肥均有助于香稻产量和品质的协同提升,且对籼型香稻增产提质效果更显著。同时生育期内累积降水量、有效积温、日照时数影响着氮肥和钾肥的产量和品质效应,分别达到800～1100 mm、2900～3400 ℃·d和800～1000 h时,结合氮肥调控可协同提高香稻产量、加工品质和蒸煮品质;分别达到500～800 mm、2900～3400 ℃·d和400～600 h时,结合钾肥调控可协同提高香稻产量、加工品质、蒸煮品质和外观品质。     

糙米加湿调质对其碾米性能影响的试验研究

该研究以糙米(含水率12.5%)为原料，采用不同加湿量将糙米加湿调质，以降低硬度和脆性。依据不同润糙时间对试样进行碾米加工试验。用SAS软件分析了润糙时间及加湿量对碾米加工的能耗、整精米率影响规律。结果表明糙米在润糙开始后60～90 min，加湿量为1.45%的情况下，碾米加工时可以降低能耗约30％，整精米率提高约10％。因此，采用加湿调质方法可以改善储藏后稻谷碾磨质量，提高精米率、降低能耗。     

Effect of Rice Kernel Thickness on Degree of Milling and Associated Optical Measurements

Three cultivars of long-grain rice were milled to three degree of milling (DOM) levels. Inverse linear relationships were established between surface fat concentration (SFC) and Satake milling meter (MM1B) optical DOM measurement values, including whiteness, transparency, and DOM, for the unfractionated head rice within each cultivar. Milled bulk rice for each cultivar was subsequently separated into thickness fractions. Effects of milled rice kernel thickness on SFC and optical DOM measurements were investigated. For a given DOM level, SFC decreased with increasing milled rice kernel thickness up to a thickness of 1.67 mm, after which it remained constant. As the overall DOM level increased, the difference in DOM between thin kernels and thick kernels lessened, implying that thin kernels were milled at a greater bran removal rate than thick kernels. Milled rice kernel thickness significantly (at the 0.05 significance level) affected MM1B whiteness and MM1B transparency in two of the cultivars because of the predominant effects of the thinner kernel fractions. Within each cultivar, MM1B DOM was not significantly influenced by milled rice kernel thickness.