Quality Attributes of Germinated High-Amylose and Waxy Rice in Superheated Steam and Hot Air Drying

In this work, the effects of amylose content, drying medium, and drying temperature on the fissure, texture, and glycemic index of germinated paddy (GP) were investigated. The amylose content, drying temperature, and drying medium affected the degree of starch gelatinization and percentage of fissure kernels significantly. Hot air drying at 130 and 150°C insignificantly influenced the hardness of Phitsanulok 2 GP with high amylose content after cooking compared to that of shade-dried GP, and the drying temperatures significantly affected the hardness and stickiness of RD6 GP without amylose content. Superheated steam drying caused a significant change in textural properties for both paddy varieties because of complete starch gelatinization. The high-amylose paddy had higher gamma-aminobutyric acid and lower glycemic index than nonamylose paddy. Drying temperature and drying media did not change the gamma-aminobutyric acid and glycemic index of both GP varieties in comparison to their shade-dried samples.     

Effects of White Rice, Brown Rice and Germinated Brown Rice on Antioxidant Status of Type 2 Diabetic Rats

Oxidative stress is implicated in the pathogenesis of diabetic complications, and can be increased by diet like white rice (WR). Though brown rice (BR) and germinated brown rice (GBR) have high antioxidant potentials as a result of their bioactive compounds, reports of their effects on oxidative stress-related conditions such as type 2 diabetes are lacking. We hypothesized therefore that if BR and GBR were to improve antioxidant status, they would be better for rice consuming populations instead of the commonly consumed WR that is known to promote oxidative stress. This will then provide further reasons why less consumption of WR should be encouraged. We studied the effects of GBR on antioxidant status in type 2 diabetic rats, induced using a high-fat diet and streptozotocin injection, and also evaluated the effects of WR, BR and GBR on catalase and superoxide dismutase genes. As dietary components, BR and GBR improved glycemia and kidney hydroxyl radical scavenging activities, and prevented the deterioration of total antioxidant status in type 2 diabetic rats. Similarly, GBR preserved liver enzymes, as well as serum creatinine. There seem to be evidence that upregulation of superoxide dismutase gene may likely be an underlying mechanism for antioxidant effects of BR and GBR. Our results provide insight into the effects of different rice types on antioxidant status in type 2 diabetes. The results also suggest that WR consumption, contrary to BR and GBR, may worsen antioxidant status that may lead to more damage by free radicals. From the data so far, the antioxidant effects of BR and GBR are worth studying further especially on a long term to determine their effects on development of oxidative stress-related problems, which WR consumption predisposes to.     

Effects of Germination Process and Drying Temperature on Gamma-Aminobutyric Acid (GABA) and Starch Digestibility of Germinated Brown Rice

In this work, germination method, germination time, and drying temperature were investigated for their effects on gamma-aminobutyric acid (GABA) and starch digestibility. The germination method and germination time influenced the GABA and dietary fiber contents as well as starch and glucose, but both factors did not provide a faster hydrolysis of starch for germinated brown rice because of the dietary fiber. When the germinated samples were dried by a hot-air fluidized bed dryer at 130 or 150°C, the GABA content was not decreased and the amylose-lipid complexes occurred. Dissociation temperature of the complexes was given in a range of 100–117°C, which was lower than that of complexes in the non-germinated paddy. Thus, the amylose-lipid complexes in the germinated samples obtained at high temperature lost some crystalline structure when cooked by the boiling method. The corresponding rate of starch hydrolysis or glycemic index of the germinated samples changed insignificantly from that of the shade-dried germinated sample or non-germinated brown rice which was dried in shade.     

流态化干燥过程的分析

通过物料在流化床干燥器上的热态实验,找到了对物料干燥过程产生影响的因素,根据实验数据和理论分析给出了应采取的有利措施。     

Effects of High-Temperature Drying on the Flavor Components in Thai Fragrant Rice

The effects of high-temperature drying on Thai Jasmine rice were investigated. Paddy was first rewetted and then dried using a two-stage drying process, involving a fluidized bed at high temperature, followed by shade drying (ambient air drying). Three high drying temperatures: 100, 125, and 150°C were studied. Volatile compounds were extracted by distillation and extraction in a Likens and Nickerson apparatus, and analyzed by gas chromatography-mass spectrometry. A total of 94 volatile compounds were identified. These included 21 alcohols, 19 aldehydes, 14 ketones, 12 acids, 9 heterocyclic compounds, 8 hydrocarbons, 5 esters, and 6 miscellaneous compounds. 2-Acetyl-1-pyrroline, a major constituent of volatiles in fragrant rice was identified and tended to increase in concentration with increasing drying temperature. The three different drying temperatures used in the fluidized bed dryer were found to have an effect on the volatile components of Thai Jasmine rice. The increase in drying temperature contributed to the formation of new compounds, as well as the loss of other desirable volatiles.     

Corn,Rice, and Wheat Seed Drying by Two-Stage Concept

Corn, rice, and wheat seeds with an initial moisture content (IMC) of 20–25% wb were dried to moisture content below 18% wb at 40–80°C in a fluidized bed dryer (FBD) and spouted bed dryer (SBD) and the seeds with IMC 18% wb were dried to below 14% wb at air temperatures 18–30°C and relative humidity 60–70% by an in-store dryer (ISD). As a result, it appears that a two-stage drying concept is feasible in drying high-moisture-content seeds due to the high germination rate of dried seeds. Nonetheless, the drying temperature must be carefully selected. A drying temperature of 40°C was clearly safe for all samples, whereas more than 90% of wheat seeds still germinated after drying at 60°C in FBD. Furthermore, drying seeds with IMC 18% wb by ISD was safe under specified drying conditions.     

Neuroprotective Effects of Germinated Brown Rice against Hydrogen Peroxide Induced Cell Death in Human SH-SY5Y Cells

The neuroprotective and antioxidative effects of germinated brown rice (GBR), brown rice (BR) and commercially available γ-aminobutyric acid (GABA) against cell death induced by hydrogen peroxide (H(2)O(2)) in human neuroblastoma SH-SY5Y cells have been investigated. Results show that GBR suppressed H(2)O(2)-mediated cytotoxicity and induced G0/G1 phase cell cycle arrest in SH-SY5Y cells. Moreover, GBR reduced mitochondrial membrane potential (MMP) and prevented phosphatidylserine (PS) translocation in SH-SY5Y cells, key features of apoptosis, and subsequent cell death. GBR exhibited better neuroprotective and antioxidative activities as compared to BR and GABA. These results indicate that GBR possesses high antioxidative activities and suppressed cell death in SH-SY5Y cells by blocking the cell cycle re-entry and apoptotic mechanisms. Therefore, GBR could be developed as a value added functional food to prevent neurodegenerative diseases caused by oxidative stress and apoptosis.     

比色法测定γ-氨基丁酸的影响因素

已有一些文献基于Berthelot显色反应研究了比色法快速测定糙米中γ-氨基丁酸含量的方法,但所用方法在一些具体操作中存在缺陷。本文通过实验摸索,完善了此类方法,结果证明采用此法制作的浓度-吸光度标准曲线相对标准偏差(RSD)可达到99.9%。在此基础上,文章还对影响测定结果的各相关因素进行了系统比较,得到了较好的检测参数。本方法简便易行,适合于推广到相关生产企业。     

己二酸生产中沸腾床干燥和气流干燥工艺性能比较

在目前己二酸生产中,用于固体物料干燥的代表性工艺是气流式及沸腾床式2种,对2种T艺在己二酸干燥中应用进行了综合性比较。     

Cytokinin Confers Brown Planthopper Resistance by Elevating Jasmonic Acid Pathway in Rice

Plants have evolved a sophisticated defense system that employs various hormone pathways to defend against attacks by insect pests. Cytokinin (CK) plays an important role in plant growth and stress tolerance, but the role of CKs in plant–insect interaction remains largely unclear. Here, we report that CKs act as a positive regulator in rice resistance against brown planthopper (BPH), a devastating insect pest of rice. We found that BPH feeding promotes CK biosynthesis and signaling in rice. Exogenous application of CKs significantly increased the rice resistance to BPH. Increasing endogenous CKs by knocking out cytokinin oxidase/dehydrogenase (OsCKXs) led to enhanced resistance to BPH. Moreover, the levels of the plant hormone jasmonic acid (JA) and the expression of JA-responsive genes were elevated by CK treatment and in OsCKXs knockout plants. Furthermore, JA-deficient mutant og1 was more susceptible to BPH, and CK-induced BPH resistance was suppressed in og1. These results indicate that CK-mediated BPH resistance is JA-dependent. Our findings provide the direct evidence for the novel role of CK in promoting insect resistance, and demonstrate that CK-induced insect resistance is JA-dependent. These results provide important guidance for effective pest management strategies in the future.     

25％吡蚜酮悬浮剂防治水稻后期褐飞虱田间示范试验

在水稻生长后期,田间褐飞虱百穴虫量6000～10000头的大发生形势下,用25％吡蚜酮防治褐飞虱每667m^2用24g,药后3d与7d的防效分别为73．69％与64．92％;每667m^2用30g,药后3d与7d的防效为78．55％与70．19％,显著优于参试的乙虫腈与烯啶虫胺。建议隔15～20d再次用药。     

Effects of High-Temperature Fluidized Bed Drying and Tempering on Kernel Cracking and Milling Quality of Vietnamese Rice Varieties

Studies on the effects of high-temperature fluidized bed drying and tempering on physical properties and milling quality of two long-grain freshly harvested Vietnamese rice varieties, A10 (32±1% wet basis moisture) and OM2717 (24.5±0.5% wet basis moisture), were undertaken. Rice samples were fluidized bed dried at 80 and 90°C for 2.5 and 3.0 min, then tempered at 75 and 86°C for up to 1 h, followed by final drying to below 14% moisture (wet basis) at 35°C by thin-layer drying method. Head rice yield significantly improved with extended tempering time to 40 min. Head rice yield tended to increase with decreasing cracked (fissured) kernels. The hardness and stiffness of sound fluidized bed dried rice kernels (in the range of 30–55 N and 162–168 N/mm, respectively) were higher than that of conventionally dried ones (thin layer dried at 35°C). The color of milled rice was significantly (P < 0.05) affected by high-temperature fluidized bed drying, but the absolute change in the value was very small.     

Rapid Drying of Parboiled Paddy Using Hot Air Impinging Stream Dryer

A method for rapid drying of parboiled paddy via the use of an impinging stream dryer was proposed and assessed. The effects of the drying air temperature, number of drying cycles, as well as time of tempering between each drying cycle on the moisture reduction, head rice yield, and whiteness index of the dried parboiled paddy were studied. The drying experiments were carried out at drying air temperatures of 130, 150, and 170°C; inlet air velocity of 20 m/s; impinging distance of 5 cm; and paddy feed rate of 40 kg_{dry_paddy}/h. Parboiled paddy was dried for up to seven cycles. Between each drying cycle the parboiled paddy was tempered for a period of either 0 (no tempering), 15, 30, 60, or 120 min. After impinging stream drying, paddy was ventilated by ambient air flow until its moisture content reached 16% (db). Moisture reduction of the paddy was noted to depend on both the impinging stream drying temperature and tempering time. Drying at a high temperature along with tempering for a suitable period of time could maintain the head rice yield of the paddy at a level similar to that of the reference parboiled paddy. To avoid discoloration and low head rice yield, parboiled paddy should not be dried at a temperature higher than 150°C and should be tempered for at least 30 min.     

Stationary versus Fluidized-Bed Drying of High-Moisture Paddy with Rest Period

Drying of high-moisture paddy was examined experimentally under stationary and fluidized bed with and without intervening rest periods. Introduction of a rest period between first and second stage of drying improved drying rate and lowered the energy requirement and increased head rice yield. Fluidization further improved the overall drying process. A single-term drying diffusion equation was suitably fitted to first, rest, and second stage drying data of fluidized and stationary bed by applying nonlinear regression method and effective diffusion coefficients were evaluated. During the period of rest stage, paddy grain released a considerable amount of moisture as an effect of residual grain temperature. An appropriate moisture ratio at which resting should start and the length of resting were evaluated by measuring changes in relative humidity in the headspace of mass of paddy and also from the diffusion coefficient values obtained from the experimental drying data. Resting duration between 75 and 90 min at moisture ratio around 0.715 was found suitable for overall good performance in both fluidized and stationary bed drying. A considerable amount of energy (21–44%) can be saved by providing a rest period from 30 to 120 min between the two stages of drying. Fluidization further reduces (≈ 50% against continuous drying under stationary bed) the energy requirement. No significant difference was found in head rice yield obtained from fluidized and stationary bed experiments, though discontinuing drying by providing intervening rest periods considerably improved the percentage head rice when compared with the results from continuous drying.     

Stationary versus Fluidized-Bed Drying of High-Moisture Paddy with Rest Period

Drying of high-moisture paddy was examined experimentally under stationary and fluidized bed with and without intervening rest periods. Introduction of a rest period between first and second stage of drying improved drying rate and lowered the energy requirement and increased head rice yield. Fluidization further improved the overall drying process. A single-term drying diffusion equation was suitably fitted to first, rest, and second stage drying data of fluidized and stationary bed by applying nonlinear regression method and effective diffusion coefficients were evaluated. During the period of rest stage, paddy grain released a considerable amount of moisture as an effect of residual grain temperature. An appropriate moisture ratio at which resting should start and the length of resting were evaluated by measuring changes in relative humidity in the headspace of mass of paddy and also from the diffusion coefficient values obtained from the experimental drying data. Resting duration between 75 and 90 min at moisture ratio around 0.715 was found suitable for overall good performance in both fluidized and stationary bed drying. A considerable amount of energy (21-44%) can be saved by providing a rest period from 30 to 120 min between the two stages of drying. Fluidization further reduces (≈ 50% against continuous drying under stationary bed) the energy requirement. No significant difference was found in head rice yield obtained from fluidized and stationary bed experiments, though discontinuing drying by providing intervening rest periods considerably improved the percentage head rice when compared with the results from continuous drying.     

Effect of Scattering by Fluidization of Electrically Conductive Beads on Electrical Field Intensity Profile in Microwave Dryers

Abstract:

A technology to apply a fluidized bed of electrically conductive beads is proposed to improve uniformity of the electric field intensity in microwave dryers, which are required for uniform heating of wet media. The principle of this effectiveness lies in a dynamic random scattering of microwave due to motion of the conductive beads in the bed. The electrically conductive beads were prepared by wrapping aluminum foil around styrene foam balls with cellophane tape. The diameter and density were 13 mm and 123 kg/m³, respectively. The minimum fluidizing velocity of these beads agreed with the one predicted by the Wen–Yu equation when the distributor was a porous plate. However, the fluidization of the beads took place at a lower gas rate than the minimum fluidizing velocity due to a jet flow from the small pores for the distributor of a perforate plate. The intensity in the applicator of a commercial microwave oven became the most uniform when the beads were fluidized with a uniform holdup profile along the height of the bed placed in front of the applicator walls. The dynamic effect making the intensity uniform by the fluidization was advanced by increasing the area of apparent reflection by the fluidized bed and the holdup of beads and was superior to a conventional stirring blade.     

Effects of High-Temperature Drying on Physicochemical Properties of Various Cultivars of Rice

Abstract

Three varieties of paddy rice, namely Langi and Amaroo from Australia and Chainart I from Thailand, were dried from high initial moisture content of about 27% down to 13–14% wet basis using a two-stage drying system. A fluidized bed dryer reduced the moisture content down to 18%. Drying experiments were carried out at 100, 125, and 150°C. Further moisture content reduction down to 14% was achieved by shade drying. As a result of these treatments, head rice yield increased proportionally with the drying temperature. In contrast to that, the yellowness, measured by colorimeter in terms of b value, showed an opposite trend. Starch characteristics were studied by Rapid Visco Analyser (RVA), x-ray diffraction, and differential scanning calorimetry (DSC). Pasting properties were affected by the drying temperature. The peak viscosity and break down were decreasing with the increase of drying temperature in all varieties while the setback values were increasing in Langi and Amaroo only. All starch samples displayed the typical A type x-ray diffraction pattern. The apparent crystallinity determined by x-ray diffraction was reduced with increasing drying temperature. The gelatinization peak shifted to higher temperature while the endothermic enthalpy of gelatinization decreased with increasing drying temperature.     

Improving Instant Rice Quality by Novel Combined Drying

The quality parameters of a new type of instant rice with higher moisture content and lower water activity (a _w) were investigated. The product was obtained after combining three types of drying processes as follows: air drying, microwave drying, and osmotic process. The new-type instant rice was evaluated by comparing it with freeze drying (FD), hot-air drying (AD), and freshly cooked rice. Several quality parameters were discussed, including color, texture, water molecule mobility, microstructure, flavor, and sensory. The comparison showed that the yellowness, hardness, and chewiness of the new-type instant rice had no significant difference with cooked rice, and it had better color and texture than FD and AD. Meanwhile, it showed much lower water molecule mobility and distinguished microstructure. In addition, the flavor and reconstituted sensory characteristic of the new instant rice were more similar to those of freshly cooked rice. In summary, the new instant rice ensured acceptable quality, and could be produced as a new form of instant rice.     

Overexpression of an Osa-miR162a Derivative in Rice Confers Cross-Kingdom RNA Interference-Mediated Brown Planthopper Resistance without Perturbing Host Development

Rice is a main food crop for more than half of the global population. The brown planthopper (BPH, Nilaparvata lugens) is one of the most destructive insect pests of rice. Currently, repeated overuse of chemical insecticides represents a common practice in agriculture for BPH control, which can induce insect tolerance and provoke environmental concerns. This situation calls for innovative and widely applicable strategies for rice protection against BPH. Here we report that the rice osa-miR162a can mediate cross-kingdom RNA interference (RNAi) by targeting the NlTOR (Target of rapamycin) gene of BPH that regulates the reproduction process. Through artificial diet or injection, osa-miR162a mimics repressed the NlTOR expression and impaired the oviposition of BPH adults. Consistently, overproduced osa-miR162a in transgenic rice plants compromised the fecundity of BPH adults fed with these plants, but meanwhile perturbed root and grain development. To circumvent this issue, we generated osa-miR162a-m1, a sequence-optimized osa-miR162a, by decreasing base complementarity to rice endogenous target genes while increasing base complementarity to NlTOR. Transgenic overexpression of osa-miR162a-m1 conferred rice resistance to BPH without detectable developmental penalty. This work reveals the first cross-kingdom RNAi mechanism in rice-BPH interactions and inspires a potentially useful approach for improving rice resistance to BPH. We also introduce an effective strategy to uncouple unwanted host developmental perturbation from desirable cross-kingdom RNAi benefits for overexpressed plant miRNAs.