Effects of parboiling and infrared radiation drying on the quality of germinated brown rice

This research investigated the physicochemical properties, bioactive compounds, and microstructure of brown rice (BR) and non-parboiled and parboiled germinated brown rice (GBR and PGBR). The GBR and PGBR were treated by sun, hot-air oven, or infrared irradiation (IR) drying. The results showed that IR drying enhanced the bioactive compounds of non-parboiled GBR, including γ-aminobutyric acid, α-tocopherol, and total phenolic compounds, while γ-oryzanol and antioxidant activity were comparable to BR. Meanwhile, IR drying significantly improved the head rice yield (HRY) of PGBR while reducing fissured grains. Parboiling also affected the color values of rice grains, suggesting the diffusion of husk color into endosperm and the formation of brown polymers by the Maillard reaction. In addition, IR drying altered the internal structure of rice grains, resulting in abundant intercellular voids. Specifically, the IR-dried non-parboiled GBR significantly enhanced essential bioactive compounds and improved HRY while maintaining the color of standard BR.     

发芽糙米微波干燥工艺研究

通过不同功率和不同干燥时间对发芽糙米营养品质和食用性能影响的分析,探索发芽糙米微波干燥适宜工艺参数。结果表明,中火(464 W)干燥8 m in、中高火(648 W)干燥5 m in、高火(800 W)干燥4 m in均可达到发芽糙米安全贮藏水分的要求,且胶稠度均大于60 mm。其中,中高火干燥5 m in时,发芽糙米中还原糖、游离氨基酸、可溶性蛋白质和抗坏血酸的含量最高,糊化温度最低。     

Microwave drying of germinated brown rice: Correlation of drying characteristics with the final quality

Drying characteristics influence the formation of quality including visual color and gamma-aminobutyric acid (GABA) of germinated brown rice (GBR) subjected to microwave drying. In microwave drying, microwave intensities induced microscopic pores inside GBR to enhance the drying rate in initial stage, while rising temperatures caused gelatinization of starch granules to hinder the drying rate in later stage. The higher microwave intensity resulted in the greater non-uniformity of temperature inside the grain layer, which dominated the moisture content and final quality indexes of GBR. However, the coupling effects of temperature rising and moisture reducing failed to stimulate the glutamate decarboxylase (GAD) activity for the GABA synthesis, but may cause the degradation of GABA. The non-uniformity of microwave drying influenced the evaluation of GABA content in the dried GBR, and the suitable average grain temperature of 64–67 °C may retain relatively high GABA content. The critical temperature for preventing the serious browning and charred kernels inside the grain layer was 132 °C and 170 °C, respectively. Microwave intensity of 3–4 W/g may be suitable for drying of GBR considering high drying efficiency and product quality.     

Effects of germination time on the structural,physicochemical and functional properties of brown rice

Germinated brown rice (GBR) is a gluten-free food raw material. Its tissue structure, physicochemical properties and functional properties depend on the germination time. In this study, rapid viscosity analyses, differential scanning calorimetry and X-ray diffraction et al were used to analyse the structural, physicochemical and functional changes in brown rice (BR) during germination. Gamma-aminobutyric acid (GABA), total phenolic compound, glutathione (GSH) and amino acid contents increased during germination. GBR exhibited the highest GSH (22.70 mg per 100 g) and amino acid (8.02 mg per 100 g) contents at 24 h and the highest GABA content (253.35 mg per 100 g) at 36 h. Furthermore, BR germinated for 36 h showed greater enthalpy (ΔH) than ungerminated BR. Although GBR showed less crystallinity than ungerminated BR, germination did not change the crystalline structure type of starch (A-type). These results inform choices of the appropriate applications of GBR to promote its utilisation in the food industry.     

超声波辅助处理对发芽糙米营养及食用品质的影响

本研究采用超声波技术辅助加工发芽糙米,探究超声波辅助处理对发芽糙米总黄酮、基本营养成分、米糠皮层微观结构及质构等的影响。结果表明,超声波辅助处理工艺顺序对发芽糙米总黄酮的含量有一定影响,其中糙米先浸泡13 h,再用160 W超声处理25 min后发芽,发芽糙米的总黄酮含量达到最大值218.17 mg/100 g。在此工艺条件下,与未超声处理组相比,发芽糙米的发芽势和发芽率分别升高了19.60%（P<0.01）和4.66%（P<0.05）;蛋白质、维生素B₂及矿物质元素（钾、磷、锰、锌）的含量均显著增加（P<0.05）;糙米皮层变得更加疏松多孔;硬度、黏着性、弹性和粘度均下降。热物性方面,发芽糙米淀粉糊化相关热物性参数无显著性变化（P?0.05）,可见超声波辅助加工能在一定程度上改善发芽糙米的功能营养特性及食用品质。     

Effect of pre‐germination time of brown rice on serum cholesterol levels of hypercholesterolaemic rats

BACKGROUND: Brown rice is unpolished rice with immeasurable benefits for human health. Brown rice (BR) and pre‐germinated brown rice (PGBR) are known to contain various functional compounds such as γ‐oryzanol, dietary fibre and γ‐aminobutyric acid (GABA). In the present study, the experimental diets containing BR and PGBR (24, 48 h pre‐germination) were used to investigate the influence of pre‐germination time of brown rice on blood cholesterol in Sprague–Dawley male rats. RESULTS: Hypercholesterolaemia and elevation of LDL‐cholesterol were successfully ameliorated by the experimental diets containing BR and PGBR (24 and 48 h pre‐germination). As compared to the control sample, the pre‐germination time had a significant (P < 0.05) effect on blood cholesterol of Sprague–Dawley male rats. It was also found that the significantly (P < 0.05) better effect on lipid profile of hypercholesterolaemic rats was observed by prolonging the pre‐germination time. As compared to non‐germinated brown rice, the germinated brown rice showed the higher cardio‐protective effect on hypercholesterolaemic Sprague–Dawley male rats. CONCLUSION: The present study suggests that the changes of blood cholesterol can be mainly modulated by using the PGBR rather than BR. The prolonging of pre‐germination time led to an increase in the bioactive components, thereby providing a more efficient functional diet affecting the high blood cholesterol. This study suggests that PGBR can be used instead of BR and polished rice in the human diet. Copyright © 2009 Society of Chemical Industry     

富铬发芽糙米粉性质分析及其在馒头中的应用研究

目的 探究富铬发芽对糙米粉性质的影响及其应用特性研究。方法 通过单因素实验明确发芽糙米中有机铬最佳富集工艺, 对普通糙米粉、普通发芽糙米粉、富铬发芽糙米粉的热力学性质、结晶结构、短程有序结构、水解氨基酸总含量及表面微观结构进行比较。将富铬发芽糙米粉应用于馒头制作, 并对糙米馒头的质构分析、感官评分进行研究。结果 糙米在浸泡时间12 h、发芽温度30℃、三氯化铬溶液质量浓度为80 mg/L时, 有机铬含量达到最高0.266mg/kg, 此时有机铬转化率为50.7%。富铬发芽糙米粉与普通糙米粉相比, 糊化焓值升高14.49%。水解氨基酸总含量升高3.37%。在小麦粉中添加20%比例富铬发芽糙米粉使馒头的硬度升高52.30%, 胶黏性升高30.64%, 咀嚼性升高32.21%, 弹性降低32.30%。此时糙米馒头的感官评分最高, 为87.7分, 最易被人们接受。结论 富铬发芽过程并未改变糙米粉的理化性质, 20%糙米粉添加比例接受度最高, 这可为富铬发芽糙米粉的应用提供参考依据。     

速食发芽糙米的研究

以糙米为原料经过发芽处理,采用蒸煮糊化法制取速食发芽糙米。运用二次蒸煮糊化法进行糊化,将预蒸煮获得的速食发芽糙米进行浸泡和第二次蒸煮,糊化完成后进行干燥处理制成速食发芽糙米。结果表明:利用正交实验确定最佳糊化条件为:预蒸煮时间25min,浸泡温度60℃,浸泡时间35min,二次蒸煮时间30min;最佳干燥温度为80℃,时间为90min。     

Process of Producing Parboiled Rice with Different Colors by Fluidized Bed Drying Technique Including Tempering

Steamer is utilized to gelatinize rice starch. High pressure or long steaming time is conventionally applied to obtain the dark brown color of the product. A new alternative method to produce dark brown parboiled rice was proposed in this work. High temperature fluidized bed drying technique including tempering was therefore explored to determine the operating condition to meet the requirement of light and dark brown parboiled rice along with high head rice yield. In addition, the couple of heat and mass transfer model was developed to determine the effective moisture diffusion coefficient, the temperature and moisture distributions within a grain kernel during drying. The effective diffusion coefficient was well correlated with grain temperature by Arrhenius equation. The drying temperature and moisture content after drying caused the drop of head rice yield. When the parboiled paddy at the intermediate moisture contents of 22 and 27% d.b. was tempered, the head rice quality was improved while the parboiled rice color was browner. To obtain high drying capacity, high head rice yield, and light brown color, the parboiled paddy should be dried at a maximum allowable temperature of 150 °C and tempered for 30 min. The tempering time should be extended to 60 min for the dark brown parboiled rice.     

Utilization of germinated and heat-moisture treated brown rices in sugar-snap cookies

Utilization of germinated brown rice (GBR) in sugar-snap cookies and effect of heat-moisture treatment of the GBR were investigated. Brown rice was germinated at 30 °C for 48 h and then a heat-moisture treatment was conducted for the moistened GBR (17 g/100 g moisture content) at 100 °C for 4 h. Sugar-snap cookies were prepared with white rice, brown rice, GBR and the treated GBR flours, as substitutes for wheat flour (30–100 g/100 g). All cookies containing rice flours, regardless of germination and heat-moisture treatment, required significantly less force to compress than did the wheat flour cookie, and this softening effect was increased as the level of rice flour substitution increased. The cookies made with the GBR flour displayed inferior physical characteristics compared to those with wheat flour, but the cookies containing the treated GBR flour showed improved physical properties with lower moisture content and higher spread factor than those containing untreated GBR flour. The cookies containing the treated GBR flours showed relatively a low degree of firming during the ambient storage. The overall results showed that the cookies with acceptable quality and improved nutrition could be prepared by partial or complete replacement of wheat flour with the heat-moisture treated GBR flour.     

Structural and chemical analysis of resistant starch effected by pre-treatments,cooking methods,reheating and storage condition in parboiled germinated brown rice (Oryza sativa)

Resistant starch (RS) content could be altered by the processing method, including pre-treatment, cooking method and storage conditions. This study determined the influence of RS formation in white rice (WR), brown rice (BR) and parboiled germinated brown rice (PGBR) as affected by various pre-treatment and processing conditions. This is the first report to chemically and structurally analyse WR, BR and PGBR of the same rice variety using X-ray diffraction, DSC and SEM. The results showed that the PGBR prepared by a non-soaking process cooked with steaming and stored cold contained RS content (92.1 mg/g, wet basis) followed by BR processed by soaking, steamed and then stored cold (91.8 mg/g, wet basis). The formation of RS3 as not affected by the parboiling and germination process compared to WR and BR. Reheating reduced resistant starch content by changing the RS structure conformation from crystalline to amorphous under higher temperatures. Moreover, the scanning electron microscope revealed that WR, BR and PGBR of the same rice variety show similar starch granule and microstructure patterns but slightly different in thermal conductivity value.     

富氢水发芽糙米加工工艺及其品质研究

本研究利用富氢水（HRW）加工发芽糙米,以富氢水浓度、发芽温度和浸泡时间为主要影响因素,以发芽势、发芽率和总黄酮含量为考核指标,在利用单因素和响应面试验建立和优化发芽工艺条件的基础上,进一步分析富氢水对糙米米糠超微结构及部分热物性参数的影响。结果表明,富氢水加工发芽糙米的最佳工艺条件为:浸泡时间13 h、发芽温度29 ℃、富氢水浓度1.5 mg/L,在此条件下糙米发芽势为67%、发芽率为84%、总黄酮含量为186.5 mg/100 g,极显著（P<0.01）高于普通纯水发芽糙米的发芽势（46%）、发芽率（70%）及总黄酮含量（130.3 mg/100 g）;此外,与普通纯水处理相比,富氢水发芽糙米米糠结构更疏松;发芽糙米糊化热焓值显著（P<0.05）低于未发芽糙米及普通纯水发芽糙米。表明利用富氢水加工发芽糙米可有效提高发芽效率、改善糙米功能活性及糊化特性,具有较好的转化应用价值。     

超声波辅助酶预处理对糙米发芽及发芽糙米理化特性的影响

结合超声波和外源酶对糙米进行预处理,利用中心组合试验模型,以超声温度、超声时间、酶质量浓度3 个因素为自变量,糙米预处理后处理液中总糖含量、糙米发芽率、发芽糙米γ-氨基丁酸（γ-amiobutyric acid,GABA）含量为响应值,设计了三因素三水平的响应面分析试验,并对数据进行拟合和相关性分析。同时研究超声波辅助酶预处理对发芽糙米中GABA含量、总酚含量、内源淀粉酶活力以及发芽糙米糊化黏度、蒸煮后质构特性的影响。结果表明：超声辅助酶预处理的超声温度和超声时间对糙米发芽率和GABA含量均有显著的影响。通过响应面分析,超声波辅助酶预处理超声温度31.21 ℃、超声时间0.71 h、酶质量浓度0.28 g/L时,发芽率最高预测值为91.98%;超声波辅助酶预处理超声温度35.65 ℃、超声时间0.5 h、酶质量浓度0.22 g/L时,GABA含量最高预测值为38.25 mg/100 g。从发芽糙米的理化特性来看,超声波辅助酶预处理有利于GABA的富集,但不利于总酚的积累。超声波辅助酶预处理可以有效地提高内源淀粉酶的活力,相应地降低发芽糙米粉的糊化黏度以及发芽糙米蒸煮后的硬度。     

发芽糙米的富硒及其微波干燥与挤压膨化工艺优化

以普通粳稻为原料,探讨了发芽糙米的富硒效果和微波干燥、挤压膨化对富硒发芽糙米营养品质的影响。结果发现,硒质量浓度为10 mg/L时,可以获得较高质量的富硒发芽糙米,此条件下糙米的发芽率为97.9%,有机硒含量为977.6 μg/kg（质量分数98.5%）,γ-氨基丁酸含量为445.9 mg/kg;40 ℃的低温微波干燥有利于保持发芽糙米的硒和γ-氨基丁酸含量;挤压膨化产品中有机硒和γ-氨基丁酸的含量与原糙米相比,分别提高到其29 倍和5 倍。研究认为,亚硒酸钠可以作为富硒试剂实现发芽糙米的有效富硒,富硒发芽糙米可以用于开发相关的营养膨化食品。     

Gamma-aminobutyric acid and glutamic acid contents,and the GAD activity in germinated brown rice (Oryza sativa L.): Effect of rice cultivars

The γ-aminobutyric acid (GABA) and glutamic acid (Glu) contents, and the glutamate decarboxylase (GAD) activity in brown rice (BR) and germinated BR (GBR) of the 5 Thai rice cultivars KDML105, PT1, CN1, SP1, and PL2 were investigated. BR was soaked at 35°C for 12 h and then germinated for 24 h to produce GBR. Amounts of GABA and Glu, and the GAD activity in samples were determined. The GABA content and GAD activity in GBR samples of all cultivars were increased 7–50× and 10–100× over levels in BR. The GABA content in BR had no effect on GABA accumulation in GBR. There was no trend in changes in the Glu content for different cultivars after soaking and germination. Variation in the GABA amount in GBR was due to both the GAD activity and the amount of Glu. These two parameters affected accumulation of GABA in all cultivars.     

Pre-Germinated Brown Rice Substituted Bread: Dough Characteristics and Bread Structure

Pre-germinated brown rice (PGBR) having the germ length of 0.5–1.0 mm is produced as a healthy food by immersing the brown rice in water. In this article, various additives were used for making PGBR breads, and suitable combinations of PGBR and additives for breadmaking were evaluated to provide PGBR bread with high functional properties. The 30% of the wheat flour was substituted with PGBR (PGBR 30), and combined additions of phytase (PHY), hemicellulase (HEM) and sucrose fatty acid ester (SE) to PGBR 30 improved the bread qualities with more suitable dough properties, as compared with the sample without their addition. During fermentation, the amounts of gas leaked from the PGBR 30 dough were suppressed by the additions. PHY and HEM hydrolyzed the phytate and hemicellulose in PGBR, and the maturity and extensibility of the PGBR 30 dough were caused by the activated yeast with formed phosphate and decomposed bran, making the large loaf volume and softness of breadcrumbs during storage. In addition, SE accelerated the dough tolerance to mixing or fermentation with the emulsifying ability. Therefore, the combined additions with PHY, HEM, and SE to PGBR 30 improved the dough and bread qualities.     

高γ-氨基丁酸营养干面条的研制

γ-氨基丁酸(GABA)作为新食品原料具有多种生理功效,为开发高GABA功能性面条,本研究以经胁迫发芽制得的富含GABA的发芽糙米和发芽大豆匀浆后,与面粉复配,通过单因素和正交实验,以制得的面条中GABA含量和感官评分为指标,优化面条配方及其加工工艺。结果显示,以50 g面粉为基准,发芽大豆匀浆液添加量为9.0 g,发芽糙米匀浆液添加量为9.0 g,食盐添加量为0.5 g,醒发时间为20 min,干燥温度为75 ℃,干燥时间为4.0 h,在此条件下制得的面条感官评价得分最高为(86.7±1.6)分,其GABA含量达到(6.96±0.13) mg/100 g DW。     

三种干燥方式处理对稻谷品质的影响研究

以旋转通风仓干燥、自然干燥和机械干燥3种方式对新收获稻谷进行降水处理。对干燥后稻谷脂肪酸值、发芽率、爆腰率、出糙率、整精米率及食味值的变化规律进行研究。结果表明:烘干稻谷脂肪酸值为19.9 mg/100 g,低于旋转仓干燥稻谷的25.3 mg/100 g和晾干稻谷的25.1 mg/100 g;高温影响稻谷种子活力,烘干稻谷发芽率为58.0%,远低于旋转仓干燥稻谷的86.5%和晾干稻谷的87.5%;另外,烘干稻谷加工成大米的爆腰率、出糙率、整精米率和食味值分别是5.33%、79.23%、57.9%、83.7,对比旋转仓稻谷的1.33%、80.27%、61.10%、87.0和晾干稻谷的2.33%、76.83%、58.9%、89.3,其加工品质和食味品质更差。利用变异系数法对3种干燥稻谷综合评分,结果表明,旋转通风仓干燥稻谷品质最优,自然干燥次之,机械干燥稻谷品质最差。实验表明,旋转通风仓干燥能很好地保护稻谷品质,适合在中国农村地区推广应用。     

纤维素酶预处理糙米发芽工艺优化

为解决发芽糙米蒸煮后口感差的问题,提出酶溶液浸泡糙米提供发芽条件的同时适当降解皮层粗纤维预处理工艺.研究酶浓度、酶解温度以及酶解时间对糙米发芽率及发芽糙米硬度的影响规律,采用二次旋转组合试验方法设计试验.并以GABA含量为考核指标,将酶预处理工艺与传统浸泡工艺进行了对比试验.结果表明:试验因素对糙米发芽率及发芽糙米硬度变化影响显著;酶预处理工艺优化参数组合为:酶浓度为0.4mg/mL、酶解温度为33℃和酶解时间为110min,在此条件下,糙米发芽率可达到传统浸泡处理的90％以上,其硬度降低14.1％.最优酶解条件下得到的发芽糙米GABA含量略低于未经酶浸泡得到的发芽糙米GABA含量.并通过扫描电镜分析证实了发芽糙米皮层粗纤维降解是其硬度下降的原因.     

Effect of high-temperature fluidized-bed drying on cooking, textural and digestive properties of waxy rice

In this work, changes of the cooking and pasting properties as well as starch digestibility of waxy rice (RD6) during hot air fluidized bed drying were investigated. Re-moistened waxy rice at an initial moisture content of 28% dry basis (d.b.) was dried at 90-150 °C. Semi-dried waxy rice was tempered and dried again by ambient air until the moisture content reached 16% (d.b). It was found that the degree of gelatinization increased with an increase in the drying temperature. At 130 and 150 °C the appearance of some waxy rice kernels changed from opaque to translucent, indicating complete gelatinization. Thermal degradation of amylopectin granules during high-temperature drying caused the starch to be more rapidly digested; this led to lower peak viscosity and setback viscosity. In addition, waxy rice processed at higher drying temperatures (90-150 °C) could adsorb more water and exhibited larger loss of solids during soaking. Such effects subsequently led to samples with lower hardness and higher stickiness. Based on the sensory analysis results, however, waxy rice dried at the above temperatures, when cooked, did not significantly differ in overall acceptability from the reference waxy rice.