不同储藏年限稻谷的品质及蒸谷米加工适应性分析

为了解不同储藏年限的稻谷加工蒸谷米的品质变化,为蒸谷米加工原料的选择提供依据。以不同储藏年限的籼稻、粳稻各40 份样品为研究对象,将其加工成蒸谷米,并对蒸谷米的蒸煮特性、外观及其制备米饭的食用品质与质构特性等指标进行测定,采用描述统计分析、方差分析、主成分分析等方法对蒸谷米的品质指标进行分析,采用聚类分析探讨稻谷的蒸谷米加工适应性。结果表明：随着原料稻谷储藏年限的延长,蒸谷米吸水率、体积膨胀率均呈上升趋势,与储藏1 年的稻谷相比,储藏4 年的籼稻和粳稻加工成的蒸谷米吸水率分别增加49.1%和35.9%,体积膨胀率分别增加70.6%和66.6%;米汤pH值、碘蓝值和固形物含量均无显著变化;感官评价总分均降低,米粒色泽加深,外观结构变差,米饭的适口性、滋味均降低,其中籼型蒸谷米的感官品质较粳型蒸谷米好;蒸谷米米饭质构特性各指标中除硬度、咀嚼性呈上升趋势以及粳型蒸谷米米饭的黏着性呈下降趋势外,其他各项指标无显著变化。在感官品质评价的基础上,引入质构特性指标分析,对蒸谷米的品质进行综合评价;并利用主成分分析,构建了蒸谷米品质评价的数学评价模型;再对综合评分进行聚类分析得出品质分类,并统计各储藏年份的样品数量,由此证实籼稻加工蒸谷米适应性优于粳稻,且储藏1、2 年的籼稻加工蒸谷米品质较好。     

柠檬酸浸泡对蒸谷糙米碾米过程中蒸谷米镉含量和品质的影响

为了解蒸谷米制备工艺中柠檬酸浸泡对蒸谷糙米的碾米特性、碾白过程中镉含量及蒸谷米品质的影响,以期依托蒸谷米加工工艺为一定程度镉污染稻米的合理利用提供数据参考。选取湖南产的2个镉含量超标的籼米样品进行蒸谷米制备,采用分层碾米的方法对柠檬酸浸泡后并经蒸煮、烘干及砻谷的糙米进行碾磨,测定不同碾白时间蒸谷米的镉含量及其碾米特性和外观品质,并测定蒸谷米的矿物质含量和蒸煮特性及其米饭食用品质进行感官评价。结果显示,柠檬酸浸泡的稻谷其蒸谷糙米的皮层更容易被碾掉,同时提高了蒸谷米单位时间的碾减率,但对蒸谷米的碎米率无显著性影响;柠檬酸会使蒸谷糙米的颜色更黄,但对蒸谷米无显著性影响;稻谷经柠檬酸浸泡促进了Cd、K、Ca、Al这4种元素自胚乳而外的迁移,对Mn和Cu元素迁移的影响较小;促进Na、Mg、Fe和Zn这4种元素由稻壳和皮层向胚乳的迁移,使蒸谷米的Na、Mg等元素的含量增加;柠檬酸浸泡后制备的蒸谷米,其米饭吸水率、体积膨胀率、碘蓝值、pH值及蒸谷米饭的硬度均显著降低,蒸谷米的色泽及其米饭的滋味、口感及综合评分等显著性提高。     

蒸谷米浸泡工艺研究

以籼稻为原料,研究浸泡工艺条件对蒸谷米品质的影响,以确定蒸谷米生产的最佳浸泡工艺条件。结果表明,蒸谷米生产工艺中最佳的浸泡工艺参数为:浸泡温度55℃、浸泡压力150kPa、浸泡时间5h。浸泡之后的稻谷吸水量较优,浸泡液中蛋白质损失量和可溶性糖损失量在吸水量达到最优的前提下保持较低水平。     

干燥方式对蒸谷米品质的影响

以稻谷为原料,以蒸谷米水分含量、出米率、整米率、裂纹率、出饭率、膨胀率、蛋白质含量以及感官评定为评价指标,系统地比较微波干燥、低温干燥、热风直接干燥、分段干燥、三段缓苏干燥这5种不同的干燥工艺对蒸谷米品质的影响。结果表明:在5种不同的干燥工艺中,低温干燥的效果最好。即浸泡温度45℃,浸泡时间5h,浸泡压力150kPa,蒸煮温度100℃,蒸煮时间10min,干燥温度90℃,干燥时间30min所得蒸谷米品质最好。     

蒸谷米加工的原料适应性及营养特性研究

以41个稻谷品种为试验材料,进行蒸谷米加工,以蒸谷米得米率、整米率、爆腰率、感官评价等指标为依据,探讨不同品种稻谷加工蒸谷米的原料适应性,并对其中蒸谷米感官评价分值最高的3个品种进行了工艺优化,同时考察了产品的营养特性。结果表明:不同品种间稻谷加工蒸谷米的得米率、整米率以及爆腰率有显著差异(P0.05),得米率最高达到77.46%,而整米率最高的达到71.24%;不同品种稻谷加工的蒸谷米产品得米率均高于同品种的白米,其中有30种差异显著(P0.05);在整米率方面,30种蒸谷米产品显著高于同品种白米(P0.05),1种显著低于对应的白米(P0.05)。感官评价最高的3个稻谷品种的最适浸泡、蒸煮工艺略有差异,其中TJ118在55℃下浸泡最适时间为5 h,而TJ292和TJ610的最适时间为6 h;TJ118蒸谷米的最适蒸煮时间为15 min,TJ292蒸谷米的最适蒸煮时间为20 min,而TJ610蒸谷米的最适蒸煮时间为25 min;相对于同品种白米,感官评价最高的3个稻谷品种加工的蒸谷米中铁、磷、维生素B_1、B_2含量均有不同程度的提高。     

RSM优化速冻方便炒饭浸泡工艺的研究

浸泡工艺作为方便米饭加工工艺中的重要影响因素,对品质影响作用较为显著.采用质构分析仪检测硬度,通过TPA模式对速冻方便炒饭的质构进行分析.通过单因素试验选取浸泡温度、浸泡时间、乙醇及糊精浓度作为Centrel Composite设计的变量,利用4因素3水平响应面法(RSM)优化浸泡工艺条件.结果表明:速冻方便炒饭制作的最佳浸泡工艺条件为:乙醇浓度1.5%,糊精浓度1.0%,浸泡时间27 min,浸泡温度25℃.     

浸泡参数与米饭品质关系的研究

根据南方米饭快餐的产业化需求和目前煮饭设备的现状,通过实验和研究,分析了大米吸水率与浸泡温度和时间的关系和浸泡参数对米饭品质的影响,并因此确定了大米浸泡吸水率与浸泡温度和时间的关系曲线和浸泡参数与米饭品质曲线。得出吸水率与温度、浸泡时间呈正比,米饭的品质与吸水率呈抛物线关系。     

不同稻谷干燥方式对浸泡前后大米品质的影响

为探究不同稻谷干燥方式对浸泡前后大米理化性质及食味品质的影响，以经过自然干燥和热风干燥处理的同一品种粳米为主要原料，探究不同稻谷干燥方式对浸泡前后大米的水分含量、水分分布、微观结构、晶型结构、糊化特性、碘蓝值、食味值以及质构特性的影响。结果表明，热风干燥组大米裂纹较多，相对结晶度、回生值、糊化温度显著低于(P<0.05)自然干燥组，而崩解值、最终黏度、米饭黏弹性和食味值显著高于(P<0.05)自然干燥组；热风干燥组大米在浸泡初期吸水率显著高于(P<0.05)自然干燥组，且当浸泡30 min时两组大米的水分含量基本达到饱和，浸泡后，两组大米的裂纹数量和宽度均明显增大，相对结晶度分别降低了1.03%～1.98%、糊化温度降低了2.45～3.40℃；峰值黏度、谷值黏度、崩解值、最终黏度、回生值和米饭黏弹性显著增大(P<0.05)，碘蓝值增加了15.60%～21.26%，米饭食味值增加至84.73～85.46。综上所述，浸泡提升了两组米饭的品质，且热风干燥组米饭品质更好。     

浸泡参数与米饭品质关系的研究

根据南方米饭快餐的产业化需求和目前煮饭设备的现状,通过实验和研究,分析了大米吸水率与浸泡温度和时间的关系和浸泡参数对米饭品质的影响,并因此确定了大米浸泡吸水率与浸泡温度和时间的关系曲线和浸泡参数与米饭品质曲线。得出吸水率与温度、浸泡时间呈正比,米饭的品质与吸水率呈抛物线关系。      

柠檬酸缓冲液对蒸谷米色泽及品质特性的影响

采用不同pH的柠檬酸缓冲液浸泡稻谷,以纯水浸泡的蒸谷米为对照组,考察了不同处理组蒸谷米的色差、加工品质、感官评价、体外消化、热力学特性和质构特性的变化,并进行了相关性分析。结果表明：低pH浸泡液预处理后,蒸谷米色差有显著变化,其中pH 4浸泡液颜色最浅,相对纯水浸泡的蒸谷米,其L^*值增加了5.27;消化结果显示,样品淀粉消化率随pH降低而降低,其中pH 3组淀粉消化率最低,其eGI值降低了11.83%,抗性淀粉增加了29.06%;加工品质结果显示,pH对出米率无显著影响,但随着浸泡液pH降低整精米率有所降低、爆腰率有所上升;感官评价和质构特性结果表明,蒸谷米的食用品质随着pH的降低先上升后下降。综合结果表明,适当低pH浸泡液预处理对蒸谷米的色泽、体外消化特性、感官品质具有一定的改善作用。     

Parboiling of rice. Part I: Effect of hot soaking time on quality of milled rice

This study investigated the effect of soaking time on the quality of parboiled rice. The paddy was soaked in water at 25 and 80 °C for 15, 30, 45, 60 and 120 min. The soaked paddy was steamed, dried, stored and milled. With increasing soaking time a significant increase in water absorption and milling and head rice yield (hence reduction in broken rice) was observed. A significant difference in milling yield, at the 1% level, was obtained between the raw rice control and the hot soaked parboiled samples. A large reduction in fissured grain was observed after soaking. It is suggested that parboiling fills the void spaces and cements the cracks inside the endosperm, making the grain harder and minimizing internal fissuring and thereby breakage during milling.     

蒸谷晚籼米的制备及其无机元素和农药残留分析

对蒸谷晚籼米加工工艺中的浸泡、汽蒸、干燥三个重要环节进行了实验,并对蒸谷晚籼米中重要无机元素含量和有机磷农药残留进行了分析。实验结果表明,蒸谷晚籼米制备过程中浸泡、汽蒸和干燥的工艺条件为:在70℃水中浸泡2.5h,于100℃下汽蒸30min,先在110℃下干燥3h后,再在60℃下干燥4h。在此条件下生产的蒸谷晚籼米爆腰率为7.6%,远低于普通白米加工的爆腰率;蒸谷后晚籼米总灰分含量比未蒸谷前增加了34.5%,其中Ca、Fe、Zn等重要无机元素的含量明显增加;此外蒸谷晚籼米中未检出有机磷农药,说明蒸谷晚籼米食用安全性高。     

Folic acid fortification of parboiled rice: Multifactorial analysis and kinetic investigation

Folic acid fortification of parboiled rice has been systematically studied to obtain quantitative insights into the role of key process variables. Parboiling was conducted with brown rice soaked at 70 °C for 1, 2 and 3 h with four different fortificant concentrations added and dried parboiled rice was milled for three durations (i.e. 0, 60 and 120 s). Both residual folate concentration in treated parboiled rice and pH of the soaking water after soaking stages were measured. Multifactorial model was developed to describe the residual folate retention behaviour and suggested that both soaking and milling were significant factors in folic acid fortification. The optimum soaking time was deduced to be 1.97 h. Folate retention rate followed a 1st order kinetics while the rates of natural rice hydrolysis and folate uptake were both time-dependent.     

浸泡对早籼稻水分含量及蒸谷米品质的影响

以早籼稻为对象,通过改变浸泡时间和温度,测定分析浸泡条件对早籼稻的水分含量、蒸谷米VB1的含量以及蒸谷米品质的影响。结果显示,浸泡条件对蒸谷米品质影响明显,当浸泡温度为75℃、时间为3.5 h时,蒸谷米的品质最好,VB1含量最高。     

浸泡工艺对糙米发芽率的影响

以早籼稻为原料,研究了其糙米的浸泡工艺对其发芽率的影响。浸泡工艺因素选取用水量、浸泡温度、浸泡时间以及浸泡液添加剂。结果表明,浸泡时用水量为糙米质量的8倍以上适宜糙米发芽,吸水率在24%～29%;适宜发芽的浸泡温度和时间组合分别为35℃浸泡6h,30℃浸泡8h;浸泡温度与时间组合在30℃浸泡8～10h,此时发芽率最高;在浸泡液中添加赤霉素或Ca2+,当浸泡液中赤霉素浓度为0.1mmol/L时,糙米发芽率最高;当浸泡液中Ca2+浓度为1.0mmol/L时,糙米发芽率最高。同时还测定了糙米和发芽糙米中主要物质还原糖、总糖、蛋白质、γ-氨基丁酸含量,并进行对比。     

EFFECT OF ARTISANAL PARBOILING METHODS ON MILLING YIELD AND COOKED RICE TEXTURAL CHARACTERISTICS

ABSTRACT

One of the main objectives of artisanal rice parboiling is to reduce the levels of broken grains (brokens) on milling. Rice samples that had been parboiled using different regimes of soaking temperatures and steaming times were analyzed for their physical properties and cooked rice textures. It was established that inappropriate soaking and steaming regimes resulted in greater levels of brokens than raw‐milled paddy. Consequently, in artisanal parboiling, the initial soaking temperature should be about 90C and the steaming time should be more than 8 min, ideally, about 12 min. On cooking, more severely parboiled rice samples had firmer textures than mildly parboiled samples. The commercially parboiled sample and the more severely laboratory‐parboiled samples required a rice‐to‐water ratio of 1:3, while the raw‐milled sample and the mildly parboiled ones required a 1:2½ rice‐to‐water ratio for optimum cooking.

PRACTICAL APPLICATIONS

Artisanal rice parboiling is carried out mainly to reduce the levels of broken grains and increase the yield of milled rice in many countries. If this is carried out very well, there are economic benefits as more rice of better quality is available to be sold. This study provides information on optimum processing conditions, i.e., initial soaking temperature of about 90C and a steaming time of about 12 min. The study also provides recommendations on optimum cooking conditions, i.e., rice‐to‐water ratio, for the variably parboiled rice samples.     

Effect of soaking medium on the physicochemical properties of parboiled glutinous rice of selected Laotian cultivars

The effect of various soaking mediums, viz. water (control), 3% NaCl and 0.2% acetic acid, and without soaking on the physicochemical properties of parboiled selected glutinous (TDK8 and TDK11) and non-glutinous (Doongara) was investigated in the present study. Results showed that the chemistry of soaking had a significant effect on the head rice yield (HRY), grain hardness, crystallinity, color, pasting and thermal properties, textural attributes, and glycemic index of these rice varieties. Soaking with NaCl and acetic acid significantly increased the grain hardness and HRY than control and without soaking treatments. Acetic acid and NaCl soaking significantly affected crystalline regions of starch resulting in reduced crystallinity in X-ray diffraction analysis and thermal endotherms in DSC analysis. NaCl soaking induced swelling of starch granules resulting in high peak and final viscosities. However, acetic acid restricted swelling resulting in reduced peak and final viscosities. NaCl and acetic acid soakings also resulted in increased hardness and adhesiveness of cooked grains than normal water soaked and un-soaked parboiled rice samples. Interestingly, change in textural attributes was prominent in parboiled glutinous rice. The color difference value for fresh parboiled samples was significantly lower for acetic acid soaked samples compared to NaCl soaked and un-soaked samples probably due to bleaching effect of acetic acid. Moreover, parboiling also resulted in significant reduction in glycemic index of glutinous rice. These findings revealed the potential application of parboiling with modified soaking techniques to improve the grain quality.     

Technological properties of microwave parboiled rice

Two rice varieties, a short grain (Giza 175) and a long grain (Giza 181), were parboiled by soaking in water at 80–85 °C for 1.5 h and then dried in the microwave oven for 3, 5, 6 and 8 min. The effect of such parboiling treatment on milling output and technological properties (cooking and eating quality) of milled rice were studied. There was a negative significant correlation between head rice and the drying time and a positive correlation between the drying time and the broken grains. The effect of such treatment on the chemical composition of milled parboiled rice, i.e. amylose, protein, fat and ash contents, showed that the amylose content of Giza 175 variety significantly decreased while not affect in Giza 181 variety. No significant differences were obtained in protein, fat and ash contents by increasing drying time. Microwave drying was more pronounced on Giza 175 variety rather than Giza 181 one. However, the optimum cooking time of the parboiled samples of the two varieties was not affected as a result of increasing the microwave drying time.     

蒸谷米浸泡工艺参数初探

通过研究浸泡温度、浸泡时间、浸泡压力对蒸谷米含水量的影响,采用正交试验优化蒸谷米浸泡工艺参数,经过中试试验修正的工艺参数为:浸泡温度55℃、浸泡压力400kPa、浸泡4 h.