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1.
Parboiling involves soaking, steaming, and drying, and soaking is important in achieving desired parboiled rice properties. This study investigated the effects of soaking temperature and commingling on rice properties prior to steaming. Rough rice of four cultivars (Taggart, CL151, XL753, and CL XL745) and their combinations at 1:1 wt ratio were soaked at 65, 70 or 75 °C for 3 h, and dried. Both soaking temperature and difference in onset gelatinization temperature (To) of individual cultivars in commingled rice affected milling and physicochemical properties. The head brown rice yield was greater when the soaking temperature was below but close to the To for individual rice cultivars, but became difficult to predict for commingled rice. Commingled rice consisting of high To rice cultivars required higher soaking temperatures to reduce chalkiness during soaking. The color attributes of commingled rice was predominately affected by the cultivar that exhibited the most change. The gelatinization properties were governed by the low-To cultivar, whereas the pasting properties were more influenced by the high-To cultivar for the commingled rice. Therefore, using commingled rice with a wide range of gelatinization temperature as a feedstock may lead to inconsistent quality of parboiled rice.  相似文献   

2.
Starch gelatinization and formation of crystalline amylose–lipid complexes during the heat/moisture treatment step in rice parboiling were studied with temperature resolved wide angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC) using flour from Puntal (24% apparent amylose) and Jacinto (12% apparent amylose) rice samples [66, 40 or 25% moisture content (mc)]. Temperature resolved WAXS showed that the crystallinity index (CI, i.e. the relative amount of A-type crystals) of non-parboiled rice flours at 66% mc, monotonically decreased between 65 °C (Puntal) and 70 °C (Jacinto) and 90 °C (both Puntal and Jacinto). These temperatures were in agreement with the respective onset and conclusion temperatures of the M1 endotherm measured by DSC. At 40% mc, the CI decreased monotonically from 65 °C (Puntal) and 70 °C (Jacinto) until 105 °C. In DSC both M1 and M2 endotherms were present. The conclusion temperature of the M2 endotherm was higher than 105 °C. At 25% mc, the CI decreased very gradually and A-type crystals were no longer present at 145 °C. Under these conditions, no DSC endotherms were detected. No type II amylose–lipid complexes were formed during heating at 66% mc. In contrast, at 40 and 25% mc, Vh-type crystals were formed from 100 and 130 °C, respectively. Non-parboiled white rice flour had a strong A-type pattern. Mildly parboiled rice had a clear A-type, with a weak Vh-type and B-type pattern. Severe parboiling resulted in partially crystalline systems with superimposed A-type, Vh-type and B-type crystals. It was concluded that the rice variety, the combination of mc and the moisture distribution in the rice kernel and the temperature during parboiling all impact the level and the types of crystals in the parboiled rice.  相似文献   

3.
Flours derived from rice varieties with different amylose content possess distinct physicochemical and molecular properties. The aim of this study was to determine optimal processing conditions for preparing rice flour-based foods with reduced starch digestibility. To do so, we evaluated the in vitro starch digestibility of rice flours with five varieties. Reducing the amount of water (from 10-fold to 4-fold of rice flour) used for cooking rice flour lowered its starch digestibility, and the magnitude of the decrease was positively correlated with amylose content. When retrogradation of cooked rice flour proceeded for 7 days, the digestibility of high-amylose rice flours declined rapidly in the first 3 days, whereas the digestibility of low-amylose rice flours declined continuously. Our analysis also demonstrated that the chain length distribution of starch molecules and the final and setback viscosity pasting properties were the most important parameters affecting the digestibility of rice flours. Based on our results, it appears possible to reduce rice starch digestibility by establishing optimum processing conditions for different varieties. We suggest a 7-fold addition of water and retrogradation for 1 day for high-amylose rice varieties and a 4-fold addition of water with 3 days of retrogradation for low-amylose rice.  相似文献   

4.
To investigate the effects of semidry-milling on the quality attributes of rice flour and rice noodles, the properties of rice flours and cooking properties of rice noodles prepared with wet-, dry- and semidry-milled rice flours were characterized. The level of starch damage of semidry-milled rice flour at 30% moisture was significantly decreased to the level of wet-milled rice flour (P < 0.05); the whiteness of dry-milled rice flour was decreased compared with wet-milled rice flour (P < 0.05), while that of semidry-milled rice flour was not; the wet- and semidry-milled rice flours showed similar morphology and water hydration properties; the dry milling method reduced significantly the hardness, chewiness, and resilience of rice noodles (P < 0.05) compared with wet-milling, but semidry-milling did not; the cooking qualities of rice noodles produced by semidry-milling were comparable to wet-milling. It indicated the semidry-milling at 30% moisture may provide the protective effects on the characteristics of rice flours, which could be used to produce similar qualities of rice noodles to the wet-milling.  相似文献   

5.
Air-classified wheat flour was dry-coated with microparticulated rice flour (30%, db) and/or microparticulated soybean hulls (up to 10%, db) using a hybridization system, and the physical properties of the dry-coated wheat flour were examined. The composite wheat flours exhibited the higher water-holding capacity but lower swelling power and oil-holding capacity than their counterpart mixtures. In pasting viscosity, the composites of wheat and rice flours had substantially lower values for peak viscosity and breakdown than did pure wheat flour. The incorporation of soybean hulls to the composites of wheat and rice flours further reduced the peak viscosity. The composites with rice flour and soybean hulls showed slightly higher melting (gelatinization) temperatures but lower melting enthalpy compared to the counterpart mixtures. By using the composite flours for the deep-fat fried doughnut preparation, the oil uptake could be substantially reduced by approximately 30%, in comparison to pure wheat flour or the mixture samples. The composite wheat flours with microparticulated rice flour and soybean hulls produced dough matrices with improved compactness and cell structure, which were attributed to the reduced fat uptake during frying.  相似文献   

6.
Air-classified wheat flour was dry-coated with microparticulated rice flour (30%, db) and/or microparticulated soybean hulls (up to 10%, db) using a hybridization system, and the physical properties of the dry-coated wheat flour were examined. The composite wheat flours exhibited the higher water-holding capacity but lower swelling power and oil-holding capacity than their counterpart mixtures. In pasting viscosity, the composites of wheat and rice flours had substantially lower values for peak viscosity and breakdown than did pure wheat flour. The incorporation of soybean hulls to the composites of wheat and rice flours further reduced the peak viscosity. The composites with rice flour and soybean hulls showed slightly higher melting (gelatinization) temperatures but lower melting enthalpy compared to the counterpart mixtures. By using the composite flours for the deep-fat fried doughnut preparation, the oil uptake could be substantially reduced by approximately 30%, in comparison to pure wheat flour or the mixture samples. The composite wheat flours with microparticulated rice flour and soybean hulls produced dough matrices with improved compactness and cell structure, which were attributed to the reduced fat uptake during frying.  相似文献   

7.
Sesame seeds were boiled and allowed to sprout under ambient condition (30±2 °C) with an objective to reduce or eliminate the bitter taste associated with them. The untreated seeds were used as a control. The proximate composition, functional and organoleptic properties of defatted sesame flour were assessed at room temperature. There was a slight increase (about 10%) in protein content of sprouted seeds. The foaming capacity of flours from untreated, sprouted and boiled seeds were 34.6, 38.5 and 11.5%, respectively. The flour from the boiled seeds had the highest foam stability. Flours from untreated or sprouted seeds, gelation started at the least concentration of 6% whereas that from boiled seed was 11%. The emulsion capacity of flours from the untreated or sprouted seeds was the same (27.6 g oil/g sample) while that from boiled seeds was 12.9 g oil/g sample. Emulsion stability with prolonged storage appeared to be more with flours from the sprouted or boiled seeds than that from the untreated ones. The water absorption properties of flours from the untreated, sprouted and boiled seeds were 8.0, 5.9 and 6.5 g H2O/g sample, respectively whereas the oil absorption capacity same (5.9 g oil/g sample). The bitter taste in flours from the untreated or sprouted was high. The bitter taste was not detected in flour from boiled seeds and the functional properties of the flour were not deleteriously affected except foaming and emulsion capacity. Therefore, this boiling method of debittering sesame seed could be practised. The quality of sesame flour obtained with this boiling method could still serve its role in traditional dishes and in the formulation of some other conventional food products.  相似文献   

8.
The subzero properties of wheat doughs were measured by dynamic mechanical thermal analysis (DMTA) and dielectric thermal analysis (DETA) over the temperature range −90 to +40 °C and by1H-nuclear magnetic resonance (NMR) T2relaxation over the range −45 to 0 °C. The experiments revealed two transitions in the dough: one independent of frequency at −10 °C (attributed to ice melting) and one dependent on frequency at −30 °C (attributed to a glass transition). The glass transition temperatures measured by DMTA moved to higher temperatures during frozen storage when the optimal water content of dough was used. A reduction in the water content eliminated this phenomenon. A similar effect of water reduction was observed by NMR studies, in which amplitude ratios and decay times were used to calculate the phase transitions. However, the glass transition recorded by NMR was independent of frozen storage with optimal water content. The changes of water state in frozen doughs were studied by ultracentrifugation (the amount of liquid phase) and NMR (freezable water based on liquid amplitude ratios). Frozen storage increased the liquid phase in dough with optimal water content. Thus, ice crystals are growing during frozen storage resulting in the concentration of polymers and a higher glass transition observed by DMTA. The increase of liquid phase during storage was substantially lower when the water content of dough was decreased. Ice crystals» growth can be minimised by reducing water content. The experiments were carried out with four different flours. The measurement of glass transition temperature by DMTA, DETA or NMR did not reveal great differences in doughs made from different flours. The amount of liquid phase was strongly flour dependent.  相似文献   

9.
The manufacture and characterization of gluten-free spaghetti based on maize flour and different vegetable flours (artichoke, asparagus, pumpkin, zucchini, tomato, yellow pepper, red pepper, green pepper, carrot, broccoli, spinach, eggplant and fennel) were addressed in this study. The screening of the vegetable flours showed that homogeneity, color, fibrous, taste and odor were the parameters that have most influenced the overall quality of the dry spaghetti. The spaghetti added with yellow pepper flour was chosen for further analysis because of its highest sensory quality; in contrast, it recorded low carotenoids content due to the high temperature of the drying process (cycle named as HTDC). Therefore, an optimization of the drying cycle was performed (lower temperature) on the yellow pepper flour (cycle named as LTDC) that resulted in an increase of the carotenoids content. Although the spaghetti with low temperature yellow pepper flour had a higher cooking loss and lower instrumental hardness when compared to the spaghetti made with only maize flour (CTRL) it however had a significantly higher protein and dietary fiber content. Moreover there was no significant difference in the amount of glucose released during in vitro digestion for this spaghetti sample with respect to the CTRL sample.  相似文献   

10.
Rice grain chalkiness is an important characteristic, but the difference between chalky and translucent parts in grains is still unclear. Here, we investigated the differences of flour made from the chalky or translucent part of rice grains in three indica and three japonica rice varieties. The chalky flour had significantly lower amylose and protein contents and looser starch granule morphology, and starches in the chalky flour had higher relative crystallinity, higher short chain content but lower long chain content than those in the translucent flour. The water states, determined with nuclear magnetic resonance, differed between the chalky and translucent flour after soaking, cooking and retrograding, and the chalky flour had more bound and free water but less constructural water than the translucent flour. Mostly, the chalky flour had lower viscosity and shorter gel consistency, but higher onset temperature and gelatinization enthalpy than the translucent flour. The results indicated that starch granule morphology would be more indicative than other attributions on pasting and gelatinization properties of chalky and translucent parts of rice grains.  相似文献   

11.
《Plant Production Science》2013,16(2):233-236
References

The kernels of Hattan-nishiki No. 1 and Kairyo-omachi have larger air spaces in the white-core tissue and are broken easily during the process of polishing when compared with those of Senbon-nishiki and Yamada-nishiki. The polishing characteristics of brewers’ rice kernels are closely related with the structure of the white-core tissue of kernels. In this study, the varietal differences in the starch properties of white-core tissue of brewers’ rice kernels on polishing characteristics were studied. The starch properties were studied by rapid visco analysis (RVA) and differential scanning calorimetry (DSC); the amylose content of the rice flour of each variety was also analysed. No significant differences were observed in the amylose content among the four varieties. The two RVA parameters, peak viscosity and breakdown, were higher in Hattan-nishiki No. 1 and no significant differences were observed in them among Senbon-nishiki, Yamada-nishiki and Kairyo-omachi. The DSC parameters, gelatinization onset and peak and conclusion temperatures, were higher in Hattan-nishiki No. 1, lower in Senbon-nishiki and Yamada-nishiki, and intermediate between them in Kairyo-omachi. These results suggest that the polishing characteristics of brewers’ rice kernels are related with not only the endosperm structure but also the starch property of white-core tissue, except for Kairyo-omachi.  相似文献   

12.
Effects of microwave irradiation on composition, structure, thermal and storage properties of rice with different milling degrees were investigated. Microwave irradiation partially inactivated the lipase and lipoxidase, damaged thiamine, and created puffed rice. In addition, the transition temperatures (To and TP) of rice were shifted to higher temperatures, and the enthalpy of gelatinization decreased after irradiation. The effect was more obvious when the power of microwave was increased. Microstructure analysis showed that stress cracks and some “explosion” were created in rice kernels after microwave irradiation. Storage property analysis indicated that free fatty acid content of all rice samples increased gradually in the process of storage. Microwave irradiation reduced the release of free fatty acids during storage. The higher the power, the lesser the free fatty acids generated. The results suggested that microwave irradiation was potentially applicable for improving storage properties of brown and milled rice.  相似文献   

13.
The thermal, paste and rheological properties of brown flours from four Indica rice subspecies with different amylose content were examined using Differential scanning calorimetry (DSC), Brabender Viscometer and rheometer. Peak, final and setback viscosities (p < 0.05) increased with increasing amylose content from Brabender micro Visco-Amylo-Graph (MVA), but the phase transition temperatures of brown rice flour from DSC (p < 0.05) decreased with increasing amylose content. Rheological properties were determined by steady shear, small amplitude oscillatory shear (SAOS) and thixotropic experiments. SAOS results showed a gel-like viscoelastic behavior with G′ higher than G″. Steady-shear results showed that the brown rice flour exhibited a non-Newtonian shear-thinning behavior and the flow curves can be well described by the Herschel-Bulkley model. The upward-downward rheograms showed that brown rice flour gel, except IR-1, had a hysteresis loop, indicating a strong thixotropic behavior.  相似文献   

14.
Volatile compounds formed during heat-treatment of wheat flour influence the application of treated flour. In this study, normal and waxy hard wheat flours before and after dry-heat treatment were subjected to headspace analysis by solid-phase microextraction of volatiles followed gas chromatography–mass spectrometry (GC/MS). The untreated waxy wheat flour contained higher levels of odor-active compounds than normal wheat flour including aldehydes, alcohols, furans, and ketones. Lipid oxidation appears to play major role in producing such odor compounds. Heat treatments, depending on the severity, alter the profile of volatile compounds. Low temperature (100–110 °C) treatments effectively eliminated cereal odor (aldehyde) and did not introduce additional odors, providing a possible way to produce low-odor flours. Heat treatments at 120 °C and higher temperatures elevated the content of pyrazines, furans, and sulfur-containing compounds which together gave a roasty aroma to the flours. Considering organoleptic properties, treatments of flours at 140 °C was superior to 160 °C. The waxy wheat flour was more prone to produce odor-active compounds than normal wheat flour during the same heat treatment.  相似文献   

15.
Starch is a major component of rice grain and thus plays an important role in grain quality. For breeding rice with improved quality, the thermal and retrogradation properties of starch may be routinely measured. Since direct measurement is time-consuming and expensive, rapid predictive methods based on near-infrared spectroscopy (NIRS) can be applied to measure these quality parameters. In this study, calibration models for measurement of thermal and retrogradation properties were built from the spectra of grain and flour samples. The results indicated that both grain and flour spectra could give similar accuracy (r2=∼0.78) in determining the peak temperature (Tp) and conclusion temperature (Tc) of gelatinization. However, flour spectra (r2=0.80) were superior to the grain spectra (r2=0.73) in measuring onset temperature (To). Furthermore, the thermal properties of width at half peak height (ΔT1/2) and enthalpy of gelatinization (ΔHg), and retrogradation properties of enthalpy of retrogradation (ΔHr) and retrogradation percentage (R%) could only be successfully modeled with the flour spectra. The models reported in the present study are usable for routine screening of a large number of samples in early generation of selection in breeding programs. For accurate assay of the thermal and retrogradation properties, however, direct instrumental measurement should be employed in later generations.  相似文献   

16.
The objective of this study was to produce wholegrain wheat flour on a laboratory-scale with particle size distributions similar to commercially-milled samples without re-milling the bran. The moisture contents of four hard winter wheat cultivars were adjusted to 7.29–7.98% (by drying), 9.00–10.6% (“as is”), and 15.6% (by tempering) prior to milling into wholegrain flour. The moisture treatments appeared to affect the partitioning of wholegrain flour particles into each of three categories: fine (<600 μm), medium (600–849 μm) and coarse (≥850 μm). When the distributions of particles were grouped into these categories, wholegrain flours made from dried and “as is” wheat fell within the values for commercial wholegrain flours, while that from tempered wheat contained more coarse particles than even the coarsest commercial wholegrain flour. Loaf volumes and crumb firmness were not significantly different between bread made from wholegrain flour that had been produced from dried or “as is” wheat, but loaf volume was significantly lower and bread crumb firmness was significantly higher when wholegrain flour from tempered wheat was used. These results show that wheat may be milled without tempering to produce wholegrain flour with particle size similar to some commercially-milled flours without needing to re-grind the bran.  相似文献   

17.
Polyphenol oxidase (PPO) activities of wheats from various classes and cultivars (grown both in the U.S.A. and in Australia), of some U.S. and Australian wheats, of wheat flours at various extraction rates and of kernels separated by size from various cultivars were measured by the oxygen electrode method. PPO activity of wheats was affected by both cultivar and growing location. Wheat flour contained on the average 3% of the PPO of the wheat grain. PPO activities of the flours increased as the flour extraction rates increased. Contrary to expectation, for a single cultivar, small kernels contained less PPO (on a weight basis and especially on a kernel basis) than did large kernels. Differences among kernels of various sizes for a single cultivar were smaller than differences in PPO among kernels of comparable sizes among various cultivars.  相似文献   

18.
The flowability of basmati and non-basmati rice flour from stone and super mill was compared. On comparing, both basmati and non-basmati rice flour from stone mill was found poor flowable. However, non-basmati flour was less flowable than basmati flour. Particle size (stone mill (StM) 114.1–129.6 μm, super mill (SM) 196.4–239.5 μm) of both the flours was significantly different. The flowability of basmati and non-basmati rice flour was significantly affected by properties viz., for non-basmati flour: the particle shape circularity (StM 0.562, SM 0.642), surface roughness (StM 146.36 nm, SM 111.28 nm) and compressibility (StM 26.08%, SM 24.22%), making it less flowable than basmati flour: particle shape circularity (StM 0.661, SM 0.768), surface roughness (StM 122.21 nm, SM 90.67 nm) and compressibility (StM 21.02%, SM 17.18%). Basic flow energy, stability index and specific energy was significantly higher in non-basmati flour, thus required more energy (StM 184.37 mJ, SM 113.15 mJ) to flow than basmati rice flour (StM 151.25 mJ, SM 96.74 mJ). Overall, the flowability was analyzed at three different pressures (3,6 and 9 kPa) and the non-basmati rice flour from stone mill was found less flowable as indicated by the flow function coefficient (1.90 at 3 kPa) in comparison to basmati (2.61 at 3 kPa) creating difficulty in bulk handling.  相似文献   

19.
The objective of this study was to produce wholegrain wheat flour on a laboratory-scale with particle size distributions similar to commercially-milled samples without re-milling the bran. The moisture contents of four hard winter wheat cultivars were adjusted to 7.29–7.98% (by drying), 9.00–10.6% (“as is”), and 15.6% (by tempering) prior to milling into wholegrain flour. The moisture treatments appeared to affect the partitioning of wholegrain flour particles into each of three categories: fine (<600 μm), medium (600–849 μm) and coarse (≥850 μm). When the distributions of particles were grouped into these categories, wholegrain flours made from dried and “as is” wheat fell within the values for commercial wholegrain flours, while that from tempered wheat contained more coarse particles than even the coarsest commercial wholegrain flour. Loaf volumes and crumb firmness were not significantly different between bread made from wholegrain flour that had been produced from dried or “as is” wheat, but loaf volume was significantly lower and bread crumb firmness was significantly higher when wholegrain flour from tempered wheat was used. These results show that wheat may be milled without tempering to produce wholegrain flour with particle size similar to some commercially-milled flours without needing to re-grind the bran.  相似文献   

20.
From a nutritional perspective, rice flour is one of the most valuable flours and it is suitable for preparing food for people suffering from wheat allergy. However, bread made from rice flour is very difficult to bake because it lacks gluten. We found that pre-fermenting of rice flour using Aspergillus oryzae facilitated a better formulation of gluten-free rice bread. Bread swelling was remarkably improved with a longer pre-fermenting period at 55 °C. The specific loaf volume (SLV) without polymeric thickeners after a 12 h fermentation was approximately 2.2-fold (2.98 ml/g) higher than that after 0 h (1.36 ml/g). An enzymatic assay of the batter indicated that protease activity during the pre-fermentation period increased from 0.38 to 1.44 U/ml and this activity correlated with bread swelling. Furthermore, a commercial protease from A. oryzae also produced similar results with an adequate SLV of 3.03 ml/g. Rheological analysis showed that batter treated with protease had an increased batter viscosity and decreased flour settling behavior because of the aggregation of flour particle after partial cleavage of storage proteins. These results indicated that the improved SLV was mainly because of an A. oryzae protease, which affected the batter rheology thereby improving gas retention before baking.  相似文献   

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