The Effects of Damaged Kernel Caused by Combine Harvester Settings on Milled Rice Free Fatty Acid Levels

Milled rice surface oil and free fatty acid (FFA) contents determine rice acceptability to the brewing industry. Both could subsequently contribute to beer off‐flavors and thus compromise milled rice brewing quality. Controlling milled rice FFA by harvesting practices could be important in maintaining brewing quality as some rough rice is damaged by hull removal and/or bran disruption during harvesting. To determine the effect of harvester speed on kernel damage, the long‐grain rice variety Cocodrie was harvested at 3 different combine harvester settings and the percent of damaged kernel (w/w) was measured. Combine harvester cylinder speed had a significant effect on rough rice kernel damage. The percentages of damaged kernels for 550, 850, and 1000 rpm cylinder speeds were 1.2%, 4.0%, and 9.0%, respectively. The FFA level of milled rice with varying amount of damaged kernels was investigated over 6 mo of storage. The faster harvester cylinder speeds resulted with time in significantly greater FFA levels in “as‐harvested” rice. The FFA content of 1000 rpm as‐harvested rice almost reached the 0.1% (w/w) level. The greater the amount of damaged kernel, the greater was the milled rice FFA level, and it was significantly greater than milled rice with no damaged kernels during accelerated storage. The as‐harvested rice with 1000 rpm had the highest FFA level, followed by 850 and 500 rpm.     

微波加热对米糠稳定性影响的实验研究

本文对微波加热稳定米糠的工艺参数，微波处理时间、料层厚度、米糠原始水分、储藏时间对米糠稳定性的影响进行了试验。结果表明，微波处理时间150—200s、料层厚度30—70mm、初始水分为15．8％—21％的米糠，经微波处理后强化贮藏，6周内游离脂肪酸(FFA)的增长率在12％以下。     

提高海南地区稻谷整精米率的工艺研究与应用

本实验以定安富硒稻谷为原料,研究稻谷水分、糙米加水调制工艺、多机碾米工艺对整精米率和能耗的影响。结合工厂实际生产需要和能耗要求,通过单因素实验得到最佳工艺条件为:稻谷水分14%,以1.2%的加湿量润糙60 min,在碾米过程中经由两道砂辊碾米机进行碾白,最后得到整精米率为52.56%,每吨米能耗为79.87 kW·h/t。     

垩白对稻米吸湿产生裂纹的影响

将有垩白与无垩白的籼稻米和粳稻米浸入相同温度的水中,测定浸水时间与稻米吸湿产生裂纹率的关系。结果表明：稻米在水中吸湿后,有垩白的稻米比无垩白的稻米容易产生裂纹;粳稻米比籼稻米容易吸湿产生裂纹;有垩白籼稻米比有垩白粳稻米裂纹率峰值更高,裂纹产生更剧烈,但裂纹率峰值出现时间滞后。     

米糠粗蛋白、粗脂肪以及粗纤维含量的近红外预测模型的建立

近红外光谱技术是一种快速无损检测物质含量和鉴别物质的现代分子光谱分析技术.本研究选用分别来自南北方共200个米糠样品(100个粳米米糠、100个籼米米糠),经过理化数据检测、近红外参数优化、光谱信息采集、光谱数据预处理、模型建立及模型优化等步骤,最终建立粳米米糠、籼米米糠及总米糠的粗蛋白、粗脂肪、粗纤维的预测模型,所建...     

籼米多孔淀粉的研制

试验以籼米淀粉为原料,通过α-淀粉酶水解籼米淀粉制备籼米多孔淀粉,探讨并获得了酶水解法制备籼米多孔淀粉的较优工艺：酶解反应温度为35℃,酶解反应时间为12 h,加酶量为酶解40%淀粉量,酶解体系pH值为4.0。并利用砂芯漏斗测定淀粉对液体的吸附能力,观察到大米多孔淀粉对液体的吸附能力大大强于大米原淀粉。     

红外加热米糠稳定化研究

研究以过氧化物酶残余活力和残余水分含量为评价指标,采用3因素3水平正交试验设计,研究了红外干燥中3个主要因素(温度60～80℃,处理时间15～25min,物料厚度20～30mm)对米糠稳定化效果的影响。结果表明:较佳处理工艺参数为:加热温度80℃,处理时间20min,物料厚度25mm。处理后的米糠过氧化物酶残余活力为3.91%,水分含量为4.24%。经过90d的贮存,红外处理后的米糠在室温下游离脂肪酸值(FFA)18.0mgKOH/g,4℃冷藏下10.1mgKOH/g,远远低于对照组(98.8mgKOH/g和56.9mgKOH/g)。说明红外处理对米糠稳定化效果非常显著,同时冷藏有助于有效抑制米糠酶的活性。强化储藏试验表明,90d后经稳定的米糠稳定性提高了5倍,充分说明红外处理能够使米糠长期稳定化。     

稻谷水热加工过程中镉迁移规律研究

目的研究稻谷在蒸谷米水热加工过程中镉的迁移规律。方法以蒸谷米小试装置及生产线采集样品为研究对象,在优化碾米时间的基础上,在排除水分含量差异对测定结果的前提下,利用统计分析考察水热工艺(浸泡和蒸煮)对稻谷各部分(稻壳、米糠和精米)镉含量的影响。结果由实验数据推断,在水热过程中,镉的迁移主要发生在稻谷的内部,且主要是在浸泡时从精米向米糠迁移富集,而蒸煮工艺则对镉的分布变化影响很小;经过浸泡,精米中的镉含量可降低约40%;推测热水的浸泡一方面使胚乳淀粉分子间游离的镉部分溶出,一方面促使镉向络合能力更强的米糠蛋白迁移,最终导致其分布发生明显变化。结论该研究为在稻谷加工过程中实现重金属镉的消减提供了科学依据。     

The breakage susceptibility of raw and parboiled rice: A review

Rice (Oryza sativa L.) is one of the most important cereals in the world. Before it is consumed, it is common to remove the hull, bran and germ from the rough rice kernel which is either parboiled or not. During such processing, rice kernels are subjected to mechanical stresses which cause some rice grains to break. A main challenge of the rice industry is to minimize the quantities of broken rice. We here review the factors impacting the breakage susceptibility of rice kernels. Their tendency to break is primarily determined by fissures, chalkiness, immaturity and rice kernel dimensions, properties which are both cultivar and rice grain history dependent. The intensity of processing of any given rice feedstock determines the actual level of broken rice kernels. If performed properly, parboiling, a three-step hydrothermal treatment consisting of soaking, heating and drying of rough rice, substantially reduces the level of broken kernels.     

Effect of drying and tempering on rice fissuring analysed by integrating intra-kernel moisture distribution

The fissure generation of one short- and two long-grain rough rice dried at different air conditions for 15, 30 and 60 min, and respectively, tempered at 20, 30, 40 and 50 °C for tempering duration ranging from 0 to 330 min was analysed by integrating moisture gradients in rice kernels. Results indicated that drying and tempering processes had significant effects on the moisture gradient and rice fissuring. The percentage of fissured kernels increased with increasing drying time and decreasing tempering time. The tempering duration required for long-grain rice was shorter than that for short-grain rice to prevent kernel fissuring. Higher tempering temperatures can effectively eliminate moisture gradients and then lower the rice fissuring generation. Tempering at 50 °C reduced fissuring incidence by 32 to 50% compared to tempering at 20 °C. Moreover, short-grain rough rice was very susceptible to fissure whereas long-grain rough rice with a high amylose content was much more fissure-tolerance.     

Effect of various processing techniques and different levels of antioxidant on stability of rice bran during storage

Rice bran is a major cereal by‐product available for animal feeding in many parts of the world. It has a good balance of protein, fat, carbohydrates, fiber, vitamins and minerals. The greatest restriction to the use of rice bran is its instability during storage, leading to rancidity and the presence of heat‐labile antinutritional factors. Rice bran was treated to stabilize it by extrusion cooking, roasting, pelleting and adding antioxidant (125, 250 and 375 ppm). The rice bran so treated was stored for 345 days and analyzed every 15 days for free fatty acid, peroxide and iodine values. Heat treatments were effective in stabilizing rice bran by reducing the rancidity and increasing the storage life. Roasting was effective in stabilizing rice bran for only 180 days of storage. Raw and pelleted rice bran behaved similarly with regard to stability during storage for 345 days. Addition of antioxidant in rice bran was not effective for stabilizing FFA, peroxide and iodine values. There was no difference in dose rates of antioxidant of 125, 250 and 375 ppm. Extrusion cooking proved to be the most effective process for stabilizing rice bran for prolonged storage, and roasting would be the next choice. Addition of antioxidant in rice bran was not effective for stabilizing rice bran during storage. Copyright © 2004 Society of Chemical Industry     

Impact of Rhyzopertha dominica (F.) on quality parameters of milled rice

The impact of Rhyzopertha dominica, the lesser grain borer, on milling quality of Francis and Wells cultivars of rough rice was assessed for the 2007 and 2008 crop years by infesting 200-g rough rice samples harvested at moderate and low moisture contents with 0, 10, 25, 50, and 100 parental adult insects, which were removed after one week. The samples were incubated for seven weeks at either 27 or 32 °C and 60% relative humidity to determine progeny production and feeding damage (insect frass), and subsequently the milled rice yield (MRY) and head rice yield (HRY). Progeny production from each parental density level varied with variety and temperature. The number of progeny produced by the parental adults was positively correlated with feeding damage, and the feeding damage caused by the progeny was in turn negatively correlated with MRY and HRY. For both years, more progeny production and feeding damage occurred in Francis versus Wells for each of the harvest moisture contents. Results show differential susceptibility of Francis and Wells cultivars to R. dominica, and also provide new methodologies for evaluating effects of infestation on rice milling quality.     

粳稻谷出米率与整精米率、出糙率相关性的研究

通过对2012年丹东质量调查的50个稻谷样品的检测,分析稻谷的出米率、整精米率、出糙率之间相关性,结果表明：稻谷的出米率与整精米率及出糙率之间存在相关性,且达到极显著水平,整精米率与出米率的相关水平要好于出糙率与出米率的相关水平,稻谷的出米率可以作为收购入库的定等指标之一。     

Development of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) on rice milling components and by-products: Effects of diet and temperature

Development of Tribolium castaneum (Herbst), the red flour beetle, was assessed on different rice components and their various by-products (i.e., diets) commonly found in rice mills, in two separate experiments. In the first experiment, eggs did not develop through to the adult stage on rough rice hulls, paddy rice dust, and milled rice dust, while eggs developed to the adult stage to some extent on rice flour, milled whole kernels, brown rice, milled broken kernels, and bran. For the diets where development occurred, the lowest percentage was on brown rice, and adults that emerged on brown rice had smaller elytra compared to adults emerging on the other diets. In the second experiment, 1–2-day old neonates were exposed on the diets listed above and held at 22, 27, 32, and 37 °C. At all temperatures, development to the pupal and adult stages was slowest on rice flour. At 22 °C, development to those stages took about twice as long compared to development at 27 °C. As temperature increased developmental times were reduced. Even though neonates developed slowest on rice flour adult emergence rates were not affected. Predictive models were used to estimate potential population development on the diets. At 22 and 27 °C, adult size as measured by elytra length was greatest when they developed on bran, while body weight was generally lowest for adults that developed on brown rice. Results show that T. castaneum can utilize rice components and by-products produced during the rice milling process, although not all components or by-products were optimal for development, and emphasis should be placed on cleaning and sanitation to remove food sources to limit infestations. Mill managers can use these results to show the importance of sanitation, and potentially improve overall pest management programs inside the mill.     

Impacts of storage temperature and rice moisture content on color characteristics of rice from fields with different disease management practices

Rice downgrading due to discoloration in storage presents a significant loss to growers and processors. The objective of this study was to investigate impacts of storage temperature and rice moisture content (MC) on color characteristics of milled hybrid rice (cv. XL 745) from fields with differing production practices. Freshly-harvested rough rice from field plots treated with and without fungicide for rice disease control during production were procured and stored at four MC levels (12.5%, 16%, 19% and 21% wet basis), and at five temperatures (10 °C, 15 °C, 20 °C, 27 °C, 40 °C) for 16 weeks, with samples taken every 2 weeks. Kinetics of mold growth and rice color were determined. It was observed that at 12.5% MC, discoloration was abated across all studied temperatures and treatments until 6 weeks of storage and increased not in excess of 20% thereafter 16 weeks. As the storage MC increased to 16%, discoloration increased and became significantly notable at the highest temperature of 40 °C. By week 16, at 40 °C storage temperature, discoloration increased significantly to 87.9% and 73% for sample lots from fungicide and non-fungicide treated plots, respectively. At the highest MC (21%), increase in rice discoloration was notable as early as after 2 weeks, across all storage temperatures, and continued to increase, especially for the highest storage temperature of 40 °C, to as high as 99.1% and 96.47%, after 16 weeks, for sample lots from fungicide and non-fungicide treated plots, respectively. There was more expression of discoloration patterns on samples stored at the highest temperature of 40 °C compared to that at lower temperatures, for both categories of sample treatments and ranges of studied MCs. Although not yet widely used for rice, this study suggested that cooling technology for rice, may have potential to extend rice storability, especially by retarding discoloration in the first few weeks after harvest.     

稻谷整精米率检验影响因素探讨

整精米率是反映稻谷品质的重要指标,对稻谷整精米率的检验影响因素进行了试验,探讨了不同水分的稻谷整精米率检验影响因素及影响程度。     

稻谷加工主要副产物的营养及功能性成分分析

为探明稻谷加工主要副产物米糠、米糠粕和白米糠的成分差异,对三者的营养成分及其功能性成分进行了测定和分析。结果表明：米糠、米糠粕和白米糠的碳水化合物含量均在50%以上,白米糠的淀粉含量最高,米糠粕中膳食纤维含量最高。米糠富含油脂和维生素E,可作为浸油的原料。白米糠富含淀粉,可作为微生物发酵原料或酿造原料。米糠粕富含优质蛋白质和膳食纤维,与白米糠和米糠相比,微生物感染小、有利于保藏。此外,米糠、白米糠和米糠粕中的人体必需氨基酸含量占氨基酸总量的45%左右,是必需氨基酸的良好来源。     

稻米胚及米胚油的品质分析

从原料米糠中分离出纯稻米胚和纯米糠,利用溶剂浸出法分别提取其中油脂并进行品质分析对比,以研究稻米胚及米胚油的营养品质。结果表明:稻米胚粗脂肪含量27.06%,粗蛋白含量19.50%,粗纤维含量4.88%,比米糠粗脂肪、粗蛋白含量明显提高,粗纤维含量降低;米胚油的酸值(KOH)、过氧化值、维生素E含量、谷维素含量、植物甾醇含量分别为21.7 mg/g、6.1 mmol/kg、43.18 mg/100 g、0.47%、3.07%,与米糠油相比,米胚油的酸值(KOH)降低了23.8 mg/g,过氧化值降低了1.7 mmol/kg,维生素E含量提高了17.18 mg/100 g,植物甾醇含量相差不大,谷维素含量降低0.93个百分点。米胚油在酸值和维生素E含量方面较米糠油具有明显优势,新鲜稻米胚既可以直接作为营养丰富的产品,也是优质食用油的原料。     

Effects of rice bran fiber on heat-induced gel prepared with pork salt-soluble meat proteins in model system

The technological effects of rice bran fiber on pork salt-soluble meat proteins in a model system were investigated. Rice bran fiber at levels of 0% (control), 0.1%, 0.5%, 1%, and 2% was added at the same time as salt-soluble meat protein to maintain similar moisture levels in all samples. Samples with increasing amounts of added rice bran fiber had higher pH, yellowness, sarcoplasmic and total protein solubilities. The moisture content, myofibrillar protein solubility and water holding capacity were the highest in the treatments containing with 1% rice bran fiber. However, the lightness and redness, textural properties decreased with increasing rice bran fiber levels. SDS gel electrophoresis did not reveal any changes in proteins regardless different rice bran fiber levels. The apparent viscosity indicated that improvements in water holding capacity and decreased texture due to added rice bran fiber.     

米糠贮藏时间对米糠可溶性膳食纤维抗氧化性质的影响

以新鲜米糠为原料贮藏0、1、3、5、10 d得到不同酸败程度的米糠,稳定化和脱脂后制备米糠可溶性膳食纤维,研究米糠贮藏时间对米糠可溶性膳食纤维抗氧化性质的影响。结果表明:随着新鲜米糠贮藏时间的延长,米糠可溶性膳食纤维的还原能力、金属离子螯合能力和清除ABTS~+·、DPPH·、·OH、O_2~-·能力均先上升后下降;米糠可溶性膳食纤维还原能力、金属离子螯合能力和清除ABTS~+·、DPPH·、·OH在新鲜米糠贮藏5 d时达到最大值,分别为0.943(OD_(700))、35.16%、32.28%、73.51%和13.83%,米糠可溶性膳食纤维清除O_2~-·能力在新鲜米糠贮藏1 d达到最大值,为60.58%。