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1.
Rice starch suspensions of 10% dry matter (DM) were treated by heat (0.1 MPa at 20–85 °C) or pressure/heat combinations (100–600 MPa at 20, 40 and 50 °C) for 15 min to investigate their gelatinization and rheological characteristics. The maximum swelling index of about 12 g water per gram of DM was obtained by thermal treatment at 85 °C, meanwhile, that of 7.0 g was observed by 600-MPa pressurization at 50 °C. The higher temperatures or pressures resulted in the higher degrees of gelatinization. Furthermore, treatments of 0.1 MPa at 85 °C, 500 MPa at 50 °C and 600 MPa at various temperatures caused complete gelatinization of rice starch. The consistency index (K) and storage modulus (G′) dramatically increased from 70 °C or 400 MPa. The G′ values were higher in pressure-treated samples than those in thermal-treated samples. Therefore, an application of pressure/heat combinations as a processing method to improve the quality of rice starch products would be possible.  相似文献   

2.
以菠萝蜜种子为原料提取淀粉,以木薯淀粉、大米淀粉、玉米淀粉和马铃薯淀粉为参照,采用体外消化试验测定菠萝蜜种子淀粉的快速消化淀粉、慢消化淀粉和抗性淀粉含量,并进行酶解动力学实验。结果表明:菠萝蜜种子淀粉快速消化淀粉、慢消化淀粉和抗性淀粉的含量分别为4.50%、19.65%和75.85%,酶解速率为0.60 h-1,平衡浓度为36.93%,酶解指数为41.43,血糖指数为62.45,属于中等血糖食物;菠萝蜜种子淀粉消化性、平衡浓度、酶解指数与血糖指数均高于马铃薯淀粉,而低于其他三种淀粉,酶解速率比马铃薯淀粉、木薯淀粉快,比大米淀粉、玉米淀粉慢。   相似文献   

3.
Germinated brown rice (GBR) recently has received renewed attention due to its enhanced nutritional value. Pasting properties and in vitro starch digestibility of GBR were examined before and after hydrothermal treatments. Steeping in water (30 °C, 24 h) raised the moisture content and germination percentage of brown rice. Pasting viscosity was substantially decreased but gelatinization temperatures and enthalpy were decreased only marginally by germination (30 °C, 48 h). However, annealing (50 °C, 24 h) and heat-moisture treatment (100 °C, 1 h at 30% moisture) after germination resulted in increased pasting viscosity and gelatinization temperatures. The hydrothermal treatments, however, induced browning reactions to darken the flour of GBR. The digestibility of starch in brown rice was increased by germination. The contents of rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) in the cooked brown rice were 47.3%, 40.8%, and 11.9%, respectively, but changed to 57.7%, 39.1%, and 3.2%, respectively upon germination. The hydrothermal treatments, however, decreased the digestibility of starch in GBR. The heat-moisture treatment decreased the RDS content in GBR near to that of native brown rice. The digestibility and physical properties of brown rice can be controlled by germination and hydrothermal treatments.  相似文献   

4.
Dry heat parboiling is a unique paddy processing technique that has been scarcely exploited. Dry heat parboiling at high temperature for short time and low temperature for long time on physical and physicochemical properties of three rice varieties differing in amylose content were studied. Hardness of the kernels increased from 66.4 N, 68.8 N and 59.8 N in raw samples to 89.1 N, 86.9 N and 59.8 N in parboiled high amylose, low amylose and waxy rice samples respectively. Rapid migration and evaporation of water from severely heated kernels caused cavity formation at the centre. Irreversible damage of amylopectin structures to leachable fractions caused continuous rise of the pasting curve. Crystallinity was thereby reduced. Parboiled high amylose samples gave X-ray diffraction patterns with peaks characteristic of A, B and V-type starch crystallinity. Crystalline starch-lipid complexes were observed in low amylose and waxy rices. The significant increase in the amount of rapidly digestible starch from 56.7%, 61.7% and 66.6% in raw samples to 92.1%, 90.8% and 94.8% respectively in severely processed rice samples and subsequent reduction in resistant starch from 24.5%, 21.2% and 18.4% to 0.4%, 1.9% and 0.1% indicated possibilities for targeted food use of the dry heat parboiled samples.  相似文献   

5.
Starch is the main glycemic dietary carbohydrate, and its nutritional quality is associated with the amount of slowly digestible starch (SDS) that is beneficial to glycemic control. In the current study, a microencapsulation of normal corn starch by zein protein and its slow digestion property were investigated. A significant increase of SDS and RS was shown for starch capsules (weight ratio of zein to starch: 1:6) containing plasticizers of glycerol and oleic acid after high temperature (≥70 °C) treatment. Further studies showed a substantially decreased viscosity and the formation of an amylose–lipid complex after starch gelatinization. Thus, the hydrophobic physical barrier of the zein matrix and the amylose–lipid complex might together limit the water accessibility and starch swelling leading to a dense packing of starch materials with a high amount of SDS. The acceptable sensory property makes it an ideal ingredient for specialty food preparation and glycemic control.  相似文献   

6.
We investigated certain properties of starch in raw and in heat-treated samples of quinoa, properties that are of importance to the nutritional quality of an infant food currently being developed. Scanning electron microscopy of the starch in raw seeds showed polygonal granules (0.6 to 2.0 µm diameter) to be present both singly and as spherical aggregates. Thermograms (DSC) of the flours showed one transition phase for gelatinisation of the starch and another for the amylose-lipid complex. The gelatinisation temperature of the starch was 67°C. Cooked samples manifested the highest degree of gelatinisation (97%), followed by the drum-dried (96%) and autoclaved (27%) samples. Separation of the starch on a SEPHAROSE CL-2B column showed the quinoa starch to be affected by the heat treatment, manifesting changes in the degree and extent of degradation. The amylograph viscosity of the quinoa flour showed no distinct peak for pasting, but the viscosity remained constant after gelatinisation. Cooking and autoclaving modified the viscosity of the paste. The drum-dried sample manifested a higher initial viscosity at 25°C. Thein vitro digestibility of raw quinoa starch determined by incubation for 60 min with -amylase was 22%, while that of autoclaved, cooked and drum-dried samples was 32%, 45% and 73%, respectively. Saponins did not affect the digestibility of the starch, though they tended to increase the amylograph viscosity. The total dietary fibre content in the cooked sample (11.0%) was significantly lower than that in the autoclaved (13.2%), drum-dried (13.3%) or raw samples (13.3%), while the insoluble dietary fibre fraction in the samples did not change with heat treatment. However, as compared with that of raw quinoa, the soluble dietary fibre fraction was reduced significantly both by cooking (0.9%) and by autoclaving (1.0%).  相似文献   

7.
Cryomilling of rice starch was evaluated as a non-chemical way to modify starch structure and properties. Cryomilling in a liquid nitrogen bath (63–77.2 K) was done to Quest (10.80% amylose) and Pelde (20.75% amylose) rice starch at five different time frames (0, 15, 30, 45, and 60 min). The viscosity of the cryomilled rice starch decreased significantly (p < 0.05) with increasing milling duration, including peak viscosity, hot-paste viscosity, cold-paste viscosity, breakdown, and consistency. Increasing milling time significantly increased (p < 0.05) water solubility index and water absorption index. Infra-red spectroscopy and X-ray diffraction crystallography both showed that the crystallinity of the cryomilled starch decreased with increasing milling time. Differential scanning calorimetry (DSC) analyses showed that after 60 min cryomilling there was partial loss of crystallinity (86% for Quest and 91% for Pelde) of both cryomilled starches. The cryomilling process modified the rice starch by causing a loss of crystallinity, that reduced its pasting temperature and increased water absorption, and by fragmentation of starch (probably the amylopectin fraction) that reduced the viscosity and increased solubility.  相似文献   

8.
This study evaluated the starch digestibility, physicochemical properties and cooking characteristics of polished rice (varieties IRGA417 and IAC202) subjected to the doses of 0 (as the control), 1, 2 and 5 kGy of gamma radiation. The highest dose decreased the apparent amylose content, peak viscosity, water absorption and volume expansion. Irradiation increased the solid loss by 119% and 187% for IAC202 and IRGA417, respectively, when comparing the higher dose with the control. For IAC202, irradiation decreased the rapidly digestible starch and increased the slowly digestible starch (SDS) and resistant starch (RS). IRGA417 showed an elevation of SDS and a reduction in RS. And 1 kGy dose of gamma radiation generated the highest level of RS for both the two varieties and presented the smallest changes in other physicochemical and cooking properties.  相似文献   

9.
Experimental gluten-free (GF) rice cookies were formulated with 100% rice flour (CTR) or by substituting 50% of rice flour with native waxy rice starch (WRS) or with three different resistant starch (RS) ingredients obtained from debranched, annealed or acid and heat-moisture treated WRS (RSa, RSb and RSc, respectively). Chemical composition, in vitro starch digestibility and physical and textural characteristics were carried out. Among cookies, RSa-cookies had the highest total dietary fibre content, the lowest rapidly digestible starch and the highest RS contents. All the three RS preparations have proved effective in increasing the proportion that tested as RS with respect to native WRS. However, the estimated RS loss for each applied RS ingredients caused by the baking process followed the order of RSa < RSc < RSb. Last, the lowest vitro glycaemic index value was measured for RSa-cookies. Among cookies, differences in colour and hardness were reported. The partial replacement of commercial rice flour with RSa could contribute to formulate GF cookies with higher dietary fibre content and likely slowly digestible starch properties more than equivalent amounts of RSb and RSc.  相似文献   

10.
Wheat bran is an important source of dietary fiber but also contains considerable amounts of phytic acid, which is known to impair mineral absorption. The present study was conducted to investigate the phytic acid reduction in coarse and fine wheat bran by fermentation with the different levels of bakers' yeast (3, 6 and 9%) for 8 h at 30 °C, incubation with the different levels of barley malt flour (2.5, 5.0, 7.5 and 10.0%) for 8 h at pH 5.2 and 55 °C, and autoclaving at the different pH levels (pH 5.0, 4.5, 4.0 and 3.5) adjusted with acetic acid for 2 h. The phytic acid content of the wheat bran was effectively reduced by all treatments, and the phytic acid lost was in the range of 88.4–96.9%. Without addition of yeast or malt flour, or autoclaving without pH adjustment, the phytic acid content of the bran samples was reduced at most to 44.9% of the initial amounts under the investigated conditions. Increasing the concentration of yeast or malt flour or decreasing the pH towards 3.5 did not enhance the phytic acid reduction. The most reduction occurred after 2 h of yeast fermentation and malt flour incubation, and after 30 min of autoclaving, which made up 92–98% of the total phytic acid loss. Extending the treatment periods contributed nominally to further increase in the phytic acid reduction, and the rate of the phytic acid loss decreased progressively.  相似文献   

11.
In this study, effects of lyophilization on the functional properties of acid modified and autoclaved corn starch preparations were investigated. RS contents and pasting properties of these starch preparations were also determined. Significant increases in solubility were observed as the hydrolysis level of the lyophilized samples increased. All of the acid-modified gelatinized–autoclaved–lyophilized samples had higher water binding values than those of native starch and heat treated oven-dried native starch. Acid-modified gelatinized–autoclaved–lyophilized samples (with storage at 95°C: GASL or without storage: GAL, before lyophilization) improved emulsion properties of soy protein solution significantly. Acid modification seems to be a prerequisite to achieve improving effect of lyophilization. While native starch did not contain any RS, the level increased to 8.1% due to gelatinization, autoclaving and oven-drying (Control 2). The RS content of Control 2 was higher than that of gelatinized–autoclaved–lyophilized native starch (N-GAL, 2.9%). The samples stored prior to lyophilization had higher RS contents as compared to the corresponding unstored samples. The highest RS content (12.4%) was observed in 2h-GASL sample. Cold viscosity was observed in the RVA curves of N-GASL, 2h-GASL, N-GAL and 2h-GAL samples. A possible mechanism/model is suggested to explain the lack or existence of a cold viscosity.  相似文献   

12.
以速冻鲜莲为原料,用微波法制备 RS3型莲子抗性淀粉;在单因素试验的基础上,运用正交试验设计法优化莲子抗性淀粉工艺参数。试验结果表明,影响莲子抗性淀粉得率的主次因素顺序为：淀粉乳浓度＞微波时间＞微波功率。经优化后的最佳制备工艺条件为莲子淀粉乳液浓度 15%,微波时间 120 s,微波功率 640 W,在此工艺条件下莲子抗性淀粉得率为 39.53%,其得率虽低于压热法和超声波辅助压热法,但所需时间较短,操作简单,适合用于抗性淀粉的工业化生产或大批量制备。  相似文献   

13.
Rheological, thermal and structural changes in high pressure (HP) treated Basmati rice flour dispersions were studied as function of pressure level (350–650 MPa), slurry concentration (with 1:5, 1:3 and 1:2 flour-to-water ratios) and holding time (7.5–15 min). Rice flour dispersions exhibited a gradual liquid–solid gel transformation as they gelatinized and/or denatured and behaved as viscoelastic fluid following HP treatment. Mechanical strength (G′) of pressurized gel increased with applied pressure and rice concentration. Differential scanning calorimeter (DSC) thermograms of rice slurry measured after pressure treatment indicated a reduction in peak enthalpy in proportion with the extent of gelatinization and/or denaturation of starch and proteins. Pressure-treated rice samples had a progressively lower gelatinization temperature. A 15 min pressure treatment at 550 MPa was found sufficient to complete gelatinization of protein free isolated rice starch while the slurry required 650 MPa. The presence of proteins might have been responsible for the slower starch gelatinization in the rice slurry during pressure treatment. The sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Fourier-transform infrared (FTIR) spectroscopy results indicated some minor changes in protein subunits and secondary structure of rice protein. This study has provided complementary information on pressure-induced changes in physical (thermal stability, overall structure) and molecular level (secondary structure) of rice protein.  相似文献   

14.
响应面法优化压热法制备莲子抗性淀粉工艺的研究   总被引：1，自引：0，他引：1  
以莲子淀粉为原料,采用压热法制备莲子抗性淀粉,通过单因素试验,研究淀粉乳浓度、压热温度、压热时间和淀粉乳pH值4个因素对莲子抗性淀粉得率的影响。利用响应面法进行分析,得到莲子抗性淀粉制备的最佳工艺条件。结果表明,所得的方程达到显著水平,压热法制备莲子抗性淀粉的最佳工艺条件为：淀粉乳浓度30％,压热温度111 ℃,压热时间10 min ,淀粉乳pH值为6~7。实际测得的莲子抗性淀粉得率为41.89％±1.23％,与理论预测值基本一致。  相似文献   

15.
Composition, Digestibility and Application in Breadmaking of Banana Flour   总被引：1，自引：1，他引：0  
Banana flour (BF) was obtained from unripe banana (Musa paradisiacal L.) and characterized in its chemical composition. Experimental bread was formulated with BF flour and the product was studied regarding chemical composition, available starch (AS), resistant starch (RS) and rate of starch digestion in vitro. The chemical composition of BF showed that total starch (73.36%) and dietary fiber (14.52%) were the highest constituents. Of the total starch, available starch was 56.29% and resistant starch 17.50%. BF bread had higher protein and total starch content than control bread, but the first had higher lipid amount. Appreciable differences were found in available, resistant starch and indigestible fraction between the bread studied, since BF bread showed higher resistant starch and indigestible fraction content. HI-based predicted glycemic index for the BF bread was 65.08%, which was significantly lower than control bread (81.88%), suggesting a “slow carbohydrate” feature for the BF-based goods. Results revealed BF as a potential ingredient for bakery products containing slowly digestible carbohydrates.  相似文献   

16.
Common commercial beans were cooked using two procedures: under pressure (autoclaving) and traditional cooking. Total starch extraction was higher in beans cooked with the traditional procedure (41.69–42.81%) than in the autoclaved samples (37.04–38.16%) and did not change during storage at 4 °C. However, available and total resistant starch levels in vitro were not influenced by the cooking procedure or storage. Retrograded resistant starch content was higher in beans cooked with the traditional process (2.65–2.79%) than in autoclaved beans (1.62–1.94%). The initial in vitro -amylolysis rate in freshly cooked beans was higher in the autoclaved preparation than in the beans cooked by the traditional process, but final hydrolysis indices (90 min) were similar for both samples. None of the bean samples showed statistical differences in -amylolysis behavior (=0.05) after storage at 4 °C for 96 hour.  相似文献   

17.
The effect of partial gelatinization and retrogradation on in vitro enzymatic digestibility of waxy rice starch was investigated, and the relationship between the residual crystallinity and digestibility measured. An aqueous dispersion of starch (5%, dry weight basis) was partially gelatinized by heating at different temperatures (60, 65, or 70 °C for 5 min). The relative melting enthalpy values of the starch samples, based on the melting enthalpy of native starch, were 69.0, 36.7, and 8.5%, respectively. Retrograded starch samples were also prepared by storing a fully gelatinized starch paste (5% starch) at 4 °C for 2, 4, or 7 d, and the relative melting enthalpy values for the starch samples were 36.7, 67.2, and 79.9%, respectively. The partial gelatinization and retrogradation changed the enzymatic digestion behavior of the waxy rice starch samples, and the changes were significant in the initial stage of digestion. The digestion rate was reduced as the melting enthalpy increased. The amounts of slowly digestible starch (SDS) and resistant starch (RS) correlated positively with the relative melting enthalpy of the partially gelatinized or retrograded starch samples. The glycemic index (GI) estimated using an in vitro digestion test correlated negatively with the relative melting enthalpy. At similar melting enthalpy levels, the partially gelatinized starch samples were more resistant to enzymatic digestion than the retrograded starch samples, indicating that the thermal history and the crystalline morphology affected the enzymatic digestion behavior of starch.  相似文献   

18.
Weedy rice, specifically red rice (Oryza sativa L.), is a major weed in rice which causes up to 80% yield loss and reduction of grain quality. Red rice accessions from Arkansas, U.S.A., were characterized to classify red rice accessions into certain phenotypic groups relevant to weedy rice management. The red rice accessions were 70% strawhull, 22% blackhull, 7% brownhull and <1% goldhull. Generally, blackhull red rice was the tallest (139 cm) and strawhull the shortest (133 cm) among all accessions. Blackhull red rice had more tillers (102/plant), smaller flag leaves (13 cm wide, 34 cm long), and flowered later (1225 heat units) than strawhull red rice which had 85 tillers/plant, 15 cm-wide and 34 cm-long flag leaves, and flowered after accumulating 1195 heat units. Morphological differences between accessions within each hull type were highly significant, showing great diversity within a hull color group as indicated by large ranges in traits. For example, blackhulls were 75–190 cm tall with 18–69 cm long flag leaves, 21–188 tillers and produced 40–949 g seed. Strawhulls were 46–189 cm tall with 18–66 cm flag leaf length, 16–172 tillers and produced 100–608 g seed. Some traits, such as seed production, differed widely between accessions within each hull color group such that the average seed production/accession for blackhull did not differ from that of strawhull weedy rice (196 vs. 192 g/plant). The onset of flowering among all accessions ranged from 56 to 126 d after planting. Red rice accessions formed six phenotypic clusters generally segregated by plant size or flowering time. Each morphotype would have different competitive abilities; thus, weedy rice management could be geared toward plant types. Highly competitive plant types would require intensive control measures to minimize yield losses and reduce the soil seed bank. Flowering dates impact stewardship strategies for herbicide-resistant or any genetically modified rice.  相似文献   

19.
Whole grain oat flour was extruded under different moisture contents (15%, 18%, 21%), barrel temperatures (100 °C, 130 °C), and screw speeds (160 rpm, 300 rpm, 450 rpm), and selected physicochemical properties, in vitro starch digestibility, and β-glucan extractability of the extrudates were analyzed. An increase in screw speed resulted in an increase in radial expansion index, water absorption index, and water solubility index. Screw speed significantly affected slowly and rapidly digestible starch. Moderate screw speed (300 rpm) led to higher slowly digestible starch with an accompanying decrease in rapidly digestible starch. Low moisture conditions (15%) resulted in the highest resistant starch and water-extractable β-glucan. Under the conditions used in this study, extrusion did not result in changes in water-extractable β-glucan molecular weight. Thus, extrusion might be beneficial in improving functionality and consumer acceptability by affecting physicochemical properties, in vitro starch digestibility, and β-glucan extractability of oat extrudates.  相似文献   

20.
The hypothesis was tested that certain physico-chemical characteristics might be used as indicators of total starch availability and rate of starch availability of milled rice. Milled unparboiled (uPB) and parboiled (PB) rice samples (n=93) were characterized using standardized methods of physical tests and chemical analyses and anin vitromethod was used for measuring the rate of starch digestion on a subsample of rice (n=26). The rice varieties were dominated by medium long, bold rice grain with high amylose rice and intermediate gelatinization temperature (GT), but a wide range in all characteristics was measured. Small amounts of resistant starch (RS) were measured in the cooked rice, indicating virtually complete starch availability. The RS of PB rice (0·4 g/100 g rice as eaten) was significantly (P<0·004) higher than the RS of uPB rice (0·1 g/100 g) however. The rate of starch digestion was significantly affected by both variety and parboiling. The starch digestion index (SDI) values of the PB samples (mean value 73·7) were significantly (P<0·001) lower than those of the uPB samples (mean value 79·0). The apparent amylose content (AC) was the strongest determinant for SDI in both uPB and PB rice. The widths and shapes of the raw grains and the elongation after cooking were correlated significantly with SDI values for the uPB rice, while the relatively mild parboiling procedure followed in this study eliminated this correlation. The minimum cooking times were correlated significantly with the SDI values in the uPB samples.  相似文献   

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