Effects of parboiling and fluidized bed drying on the physicochemical properties of germinated brown rice

Changes in physicochemical properties of germinated brown rice (GBR) and parboiled germinated brown rice (PGBR) dried in a fluidized bed dryer at 110–150 °C were investigated. Results indicated that parboiling altered the properties of GBR owing to starch gelatinisation. The moisture content, yellowness, peak viscosity and hardness of PGBR increased, but internal fissured kernel, cooking time, water absorption and total solids loss decreased when compared to GBR. γ‐aminobutyric acid (GABA) content in GBR was 23.31 mg per 100 g and was reduced to 17.91 mg per 100 g in PGBR. The drying times required to reduce the moisture content of GBR and PGBR to 16% d.b. were 4.01–7.65 min and 5.11–9.50 min, respectively. Final moisture content, which is optimum to prevent internal fissures of dried GBR and PGBR, was 27–29% and 25–28% d.b., respectively. The same trend was observed in the physicochemical properties of GBR and PGBR when increasing drying temperature and time.     

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     

Antioxidant activity of white rice,brown rice and germinated brown rice (in vivo and in vitro) and the effects on lipid peroxidation and liver enzymes in hyperlipidaemic rabbits

Antioxidant activity of different rice extract and the effect on the levels of antioxidant enzyme activity, superoxide dismutase (SOD) and glutathione peroxidase (GPx), vitamin E, lipid peroxidation and liver enzymes in hyperlipidaemia rabbits were investigated. Germinated brown rice (GBR) has the highest antioxidant activity compared to white rice (WR) and brown rice (BR). All rice grains increased the activity of SOD and GPx. However, vitamin E levels increased only in the groups that received the BR and GBR diets. The reduction of lipid peroxidation levels and activity of hepatic enzymes (alanine transferase, ALT and aspartate transaminase, AST) were only significantly observed in the GBR group. In conclusion, GBR supplementation has the greatest impact on increasing antioxidant enzyme activity and vitamin E level and on reducing lipid peroxidation in hypercholesterolaemia rabbit, thereby preventing the formation of atherosclerotic plaques. Furthermore, GBR diet can also reduce the level of hepatic enzymes.     

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.     

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.     

Quantitative microbiological profiles of brown rice and germinated brown rice

Among health conscious people, brown rice (BR) and germinated brown rice (GBR) are increasingly more popular for consumption in Korea because their nutritional values are greater than those of ordinary white rice (WR). The overall microbial counts for BR were higher than those for WR and those of GBR were higher than those of BR. Interestingly, the lactic acid bacteria (LAB) counts in GBR increased markedly and their selected representatives were Weissella confusa, Pediococcus pentosaceus, and Lactobacillus fermentum. To our knowledge, this is the first attempt to enumerate and compare LAB loads on WR, BR, and GBR.     

Effects of parboiling,storage and cooking on the levels of tocopherols,tocotrienols and γ-oryzanol in brown rice (Oryza sativa L.)

Vitamin E and γ-oryzanol display a wide range of biological activities including hypocholesterolemic, anti-inflammatory and antioxidant activities. Although white rice is far more popular worldwide, consumption of brown rice is increasing, partially on account of the presence of bioactive compounds; however, the effects of parboiling, storage and cooking on them are not well-characterized. The effects of parboiling and a 6-month storage period on the contents of vitamin E and γ-oryzanol in three brown rice cultivars grown in three different locations in Brazil were investigated. Also, their levels in branded non-parboiled and parboiled brown rice were monitored before and after cooking. Vitamin E homologues and γ-oryzanol were separated by RP-HPLC equipped with PDA and fluorescence detectors. The average levels of total tocols and γ-oryzanol in the raw brown rice cultivars studied were 25 and 188 mg/kg, respectively. Of the vitamin E homologues, γ-tocotrienol contributed with 74% of total tocols, followed by α-tocopherol, α-tocotrienol and γ-tocopherol in minor quantities. The combined processes, parboiling, storage and cooking, led to an approximate 90% reduction in tocols and only γ-tocotrienol was detectable after any of the processes. Parboiling followed by storage resulted in an approximate 40% loss of γ-oryzanol. Cooking had almost no further effect over γ-oryzanol levels in parboiled rice previously stored for 6 months.     

Bioactive compounds in rice during grain development

The bioactive compounds in two developing rice grains, KFSW (a waxy indica red rice) and TK16 (a non-waxy japonica rice), were investigated. The total phenolics and total flavonoids of two developing rice grains were significantly higher than those in mature seeds. The phenolics extract was further fractionated into three fractions, free, soluble-ester and insoluble-bound; ferulic acid was the most abundant compound in each fraction, in both immature grain and mature seed. α-Tocopherol was the most abundant vitamin E homologue, followed by γ-tocotrienol in KFSW and α-tocotrienol in TK16. High contents of free and soluble-ester ferulic acids, soluble dietary fibre, total tocols and oryzanols were found in the 15th and 18th DAA (days after anthesis) grains, which were suitable for dehulling, with a reasonable brown rice yield. Immature rice grains, containing a remarkable amount of bioactive compounds with a high reducing power, have a great potential for applications in nutraceutical foods.     

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.     

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.     

Assessment of Rhyzopertha dominica (F.) progeny and feeding damage on rice dried with infrared radiation

Infrared radiation (IR) is a method of drying grains that eliminates insect and microbial pests. It is unknown if IR could cause grains to be more susceptible to insects. Thus, the effects of IR on Rhyzopertha dominica development and feeding damage using long-grain rice varieties, Clearfield XL745 (hybrid) and CL152 (pureline), were examined. Rough rice was dried with three IR intensities: 2.15, 2.83, and 10.84 kW/m². The number of progeny developed, feeding damage, and frass weight after IR-drying were compared with air-drying methods for rough rice and rice milled to brown rice after drying. Since R. dominica develop internally, X-ray technology was used to examine internal progeny and feeding damage. Progeny development and kernel damage appeared to be more affected by fraction (brown rice) than the cultivar of rice or intensity of IR used, with more progeny produced on brown rice than rough rice. An IR intensity of 10.84 kW/m² increased the number of overall progeny, the amount of adults, and frass produced on CL152 brown rice. An intensity of 10.84 kW/m² also increased the amount of larvae observed for both varieties and fractions. The intensity of 10.84 kW/m², under the conditions of this study, is not recommended for drying rice.     

Effect of pulsed electric fields – assisted extraction on anti-inflammatory and cytotoxic activity of brown rice bioactive compounds

The bioactive compounds of brown rice exhibit many beneficial health effects, ranging from antioxidant to cytotoxic activities. Pulsed Electric Field (PEF) pretreatment can significantly enhance their extraction, through the induction of the electro-permeabilization of the cell membranes.This paper aims to demonstrate that PEF-assisted extraction of brown rice enables not only enhanced yields of antioxidant compounds, such as γ-oryzanol, polyphenols and phenolic acids, and of saturated and unsaturated fatty acids, but also increased cytotoxic effects on cancer cells.Initially, the PEF-assisted extraction conditions have been defined by the assessment of the cell permeabilization index via impedance measurements and the DPPH antioxidant activity. Subsequently, the biological effects of PEF have been evaluated on the cytotoxicity and anti-inflammatory properties against human colon cancer cell line HT29.The results show that PEF-assisted extraction, enhancing the yield of bioactive compounds, with respect to untreated extracts, significantly promotes their antioxidant activity, which is correlated with an increased HT29 cells cytotoxicity. In addition, PEF extracts of brown rice substantially inhibit also gene expression and interleukin production in colon cancer cells, suggesting their exploitation as natural anti-inflammatory agents.The integration of PEF pretreatment in the solvent extraction process of bioactives from brown rice appears, therefore, as a promising practice to significantly enhance their biological activity.     

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.     

Rice degree of milling effects on hydration,texture, sensory and energy characteristics. Part 2. Cooking using fixed,water-to-rice ratios

The purpose was to assess the effects of degree of milling on hydration and textural characteristics of rice cooked using a range of water-to-rice ratios, and to compare the energy requirements when using these fixed water-to-rice ratios to the energy required when cooking with excess-water. Surface lipid contents (SLCs) ranged from 0.15% to 0.55% for non-parboiled rice and from 0.40% to 0.95% for parboiled rice. Cooking degree was assessed by measuring cooked-rice peak force, moisture content and percentage gelatinized kernels. Milling degree had little to no effect on cooking characteristics of all milled samples. Differences in cooking characteristics between milled and brown rice were less pronounced for parboiled than non-parboiled rice. Non-parboiled milled rice required the least energy to be ‘well-cooked’, followed by parboiled milled rice, non-parboiled brown rice, and parboiled brown rice (there were no significant differences between non-parboiled and parboiled brown rice). In general, excess-water cooking required more energy than fixed water-to-rice ratio cooking.     

Comparison of chemical compositions and bioactive compounds of germinated rough rice and brown rice

The aim of the study was to compare changes in the chemical compositions and bioactive compounds of germinated rough rice and germinated brown rice. Ungerminated rice (brown rice) and germinated rice extract powder were also prepared, for comparison purposes. In general, the concentration of crude protein, total free amino acids, α-tocopherol, γ-oryzanol, thiamine, niacin and pyridoxine, in the germinated rough rice and the germinated rice extracted powder, were significantly higher, than those of the germinated brown rice and the ungerminated rice, whilst there was no significant difference in the levels of crude fat, carbohydrate and ash. The amino acid contents of the germinated rice products were also investigated and differences were found amongst these samples. The most significant changes, in γ-aminobutyric acid, glycine, lysine and leucine, were observed in the germinated rough rice and the germinated rice extracted powder.     

Effect of different soaking and germination methods on bioactive compounds of germinated brown rice

Germination of brown rice can be completed by full soaking and partial soaking methods. This study aimed to analyse the influence of germination methods on the bioactive accumulations in germinated brown rice (GBR). Germination was conducted in four treatments: (i) membrane reactor with full (RFS) and (ii) partial soaking method soaking (RAG), (iii) manual soaking for complete germination (MFS) and (iv) partial manual soaking in combination with atmospheric germination (MAG). The results showed that soaking BR in membrane reactor accelerated the shoots' growth and increased GABA (γ-aminobutyric acid) content compared with the manual soaking method. The RAG treatment achieved higher GABA content (up to 125 mg/100 g), total phenolic and flavonoid content, and antioxidant activity than other germination methods. The main finding of this research indicates that membrane reactor effectively enhances the growth of sprouts. The combination of partial soaking in membrane reactor and atmospheric germination (RAG) is a suited method to increase GABA accumulation in GBR.     

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.     

Rice degree of milling effects on hydration,texture, sensory and energy characteristics. Part 1. Cooking using excess water

The purpose was to assess the effect of degree of milling (DOM) on cooking kinetics, sensory attributes, and energy requirements when cooking rice in excess water. Commercial milling equipment was adjusted to produce parboiled and non-parboiled rice samples that were milled to varying DOMs, including brown rice lots having no milling. Surface lipid content (SLC) ranged from 0.15% to 0.55% for non-parboiled rice and from 0.40% to 0.95% for parboiled rice. The percentage gelatinized kernels, moisture content, peak force and sensory attributes were determined as a function of cooking duration for all samples. The cooking duration required to attain ‘well-cooked’ rice was determined, after which the energy required for cooking was measured. Within the SLC range tested, DOM did not affect cooking kinetics, texture and flavor of rice. Non-parboiled brown rice required the most energy, expressed as energy per unit mass of uncooked rice, to be cooked, followed by parboiled brown, parboiled milled and non-parboiled milled rice.     

球磨微细化研磨对发芽糙米粉物性特征的影响

本文以发芽糙米为原料,利用扫描电子显微镜（SEM）、傅里叶红外光谱（FTIR）等手段探究了微细化研磨处理对发芽糙米粉干燥前后微粒粒径、微观形貌特征、水合性能、蛋白二级结构特征的影响。结果表明,经球磨处理后,发芽糙米粉的粒径明显降低,淀粉颗粒形貌与晶体结构遭到破坏,部分微粒外壳坍塌,喷雾干燥后颗粒变得细小且均匀,小颗粒的团聚现象减少;球磨处理2 h和喷雾干燥处理后,总的水合性能显著增强;蛋白质结构更为伸展,受剪切力影响,淀粉有序结构遭到破坏。球磨研磨发芽糙米粉粒径微细且分布均匀,颜色更白,具有良好溶解性、分散性和口感,并且经过冲调后形成了具备良好黏弹性的米浆,研究为球磨研磨处理全谷物提供基础数据与参考。     

Penetration of juice into rice through vacuum drying

Vacuum drying was employed to penetrate rice with juice. Red beetroot juice, good source of color and functional compounds, was used. After mixing with beetroot juice and vacuum drying, cracks were formed in the rice kernel surface and the rice kernels were a red-violet color. The degree of visual kernel surface cracking, the fracturability of whole rice kernels, and the DPPH scavenging activity were increased with increasing amounts of added juice. The visual kernel surface cracking was found to be beneficial for deep penetration and juice accumulation within three varieties of rice kernels (Sanpatong 1, Kaow Dok Mali 105, and Chainat 1) and two storage time periods (one month and one year). The final moisture content of the rice kernels after vacuum drying was sufficiently low for good storage quality. No heat treatment is required. The findings imply that other functional liquids/solutions would be also vacuum-impregnated in rice grains. Functional properties of rice could be effectively improved with a vacuum drying technique.