Physicochemical,Morphological, Thermal and Pasting Properties of Starches Isolated from Rice Cultivars Grown in India

Physicochemical, morphological, thermal, and pasting properties of starches, isolated from basmati (HBC-19 and Bas-370) and non-basmati (Jaya, a coarse cultivar; P-44 and HKR-120, the medium cultivars and Sharbati, fine cultivar) rice cultivars grown in India were studied. The amylose content of starches from different cultivars ranged from 2.25 (Jaya) to 22.21 g/100 g of starch (HBC-19). Jaya, HKR-120, and P-44 cultivars showed soft gel consistency as 84, 73, and 69 mm, respectively, whereas Sharbati, Bas-370 and HBC-19 cultivars showed medium gel consistency as 54, 53, and 58 mm, respectively. Swelling power (at 95°C) indicated a significant positive correlation with amylopectin content (r = 0.828, p < 0.05) and gel consistency (r = 0.983, p < 0.01). Turbidity had a highly significant positive correlation with solubility (r = 0.919, p < 0.01) and amylose content (r = 0.945, p < 0.01). Starch form Jaya cultivar showed the presence of smallest size granules (2.4–5.7 μm) with an average size of 3.96 μm, whereas Bas-370 showed the presence of largest size granules (3.3–6.7 μm) with an average size of 5.0 μm. The transition temperatures, enthalpy of gelatinization (ΔH_gel), peak height index (PHI) and gelatinization range were determined using differential scanning calorimetry (DSC). The starch from Sharbati cultivar showed highest onset temperature (T_o), peak temperature (T_p), conclusion temperature (T_c), enthalpy of gelatinization and peak height index (PHI) of 68.8°C, 73.2°C, 79.0°C, 11.56 J/g and 2.63 respectively. Pasting temperature of rice starches varied from 68.9°C (Jaya) to 74.5°C (Sharbati). The peak viscosities observed were in the range of 2223 to 3297 cP, lowest for HBC-19 starch and highest for Jaya starch.     

Effect of Sodium Dodecyl Sulphate on the Physicochemical,Thermal and Pasting Properties of Cassava Starch

The effect of different concentrations of sodium dodecyl sulphate (SDS) on cassava starch properties after complexation and in situ addition were studied. The swelling volume of the starch‐SDS complexes increased to a maximum of 100 mL/g with increase in concentration of SDS (even at 0.004 mol SDS) with a corresponding decrease in solubility. During in situ addition also, a similar but gradual behaviour was observed for swelling volume and solubility. The apparent and total amylose contents showed an irregular trend. The soluble amylose content decreased with increase in concentration of SDS. In vitro enzyme digestibility of starch‐SDS complexes was significantly lowered compared to that of native starch. The water‐binding capacity showed an initial decrease followed by a significant increase at higher concentrations of SDS. DSC studies showed that in addition to the gelatinisation endotherm, a peak corresponding to the melting of the starch‐SDS complex was obtained in the case of in situ addition of the surfactant. The peak viscosity of starch during in situ addition of SDS exhibited a rapid increase except at the highest concentration. The peak viscosity of starch‐SDS complexes underwent an initial reduction followed by a gradual increase at higher concentrations. The breakdown, setback and pasting temperature were also affected.     

Comparison of Rice Flour Pasting Properties using Brabender Viscoamylograph and Rapid Visco Analyser for Evaluating Cooked Rice Texture

Pasting properties of ten Thai rice varieties, with amylose contents in the range of 16 to 33% and stored at 10, 30 and 40 °C for six months were compared using the Brabender Viscoamylograph (VAG) and the Rapid Visco Analyser (RVA) for evaluating the texture of cooked rice. Linear correlations between pasting temperature and viscosity parameters based on RVA showed a different pattern than those based on VAG with high negative correlation coefficients between the peak and breakdown viscosities. Both RVA and VAG indicated peak viscosity to be positively correlated with breakdown viscosity, and negatively with the setback viscosity. Setback and consistency viscosities correlated with each other in both instruments but indicating a negative correlation with breakdown viscosity in VAG only. Pasting temperature determined by VAG and RVA did not show good correlations for rice sample stored at different temperatures neither for individual nor for combined data. Only peak, breakdown and setback viscosities showed significant correlations in the overall data (r > 0.496). The VAG measurements performed better than the RVA in the development of predictive models for evaluating the hardness and adhesiveness of cooked rice based on instrumental texture profile analysis. The springiness and cohesiveness of cooked rice could not be estimated from the pasting properties of rice flour determined by both VAG and RVA. Results showed that both VAG and RVA could be used for evaluating the texture of cooked rice despite the differences in the measurements of the pasting properties of milled rice flours.     

稻米淀粉黏滞性和质构性研究

用快速黏度分析仪和质构仪分析了不同直链淀粉含量的籼稻淀粉质构性和黏滞性,结果表明,直链淀粉含量与淀粉质构性和黏滞性的相关性达显著水平。淀粉质构性和黏滞性存在密切关系,淀粉凝胶硬度与消减值极显著正相关,γ为0.84**,与崩解值极显著负相关,γ为-0.78**;淀粉凝胶的黏度与消减值和崩解值的γ分别为-0.84**和0.79**。稻米淀粉的质构性指标对黏滞性指标的回归方程的决定系数分别是0.734、0.600和0.716,达极显著水平,硬度受消减值的影响较大,凝聚性受崩解值影响大,黏度同时受最终黏度和消减值的影响。     

均质及大米蛋白对大米淀粉糊化和质构特性的影响

利用均质机在20～100 MPa压力下处理大米淀粉(RS),在添加或不添加大米蛋白(RP)情况下,考查大米淀粉理化性质、糊化和质构特性的变化。研究结果表明:随着处理压力的增加,RS的溶解度、膨胀率和透光率分别从1.90%、3.37%、6.27%上升至2.88%、5.38%、14.17%,凝沉性则下降;添加大米蛋白后,同一处理压力下,淀粉的溶解度、膨胀率下降,凝沉性上升。糊化特性分析发现,均质处理后,RS的最终黏度、崩解值和回生值分别下降了17.75%、24.47%和16.45%,说明其热稳定性提升,抗老化能力增强;原淀粉和60 MPa压力处理后的淀粉在添加氯化钠后糊化温度上升,黏度、降落值、回生值均有所下降,添加大米蛋白后淀粉黏度下降,回生值上升。质构特性分析发现,随处理压力的增加,淀粉凝胶的硬度从1 743 g下降到1 398 g,弹性则变化不大,大米蛋白使淀粉的硬度下降而弹性升高。     

Some properties of corn starches II: Physicochemical,gelatinization, retrogradation,pasting and gel textural properties

The physicochemical, thermal, pasting and gel textural properties of corn starches from different corn varieties (African Tall, Ageti, Early Composite, Girja, Navjot, Parbhat, Partap, Pb Sathi and Vijay) were studied. Amylose content and swelling power of corn starches ranged from 16.9% to 21.3% and 13.7 to 20.7 g/g, respectively. The enthalpy of gelatinization (ΔH_gel) and percentage of retrogradation (%R) for various corn starches ranged from 11.2 to 12.7 J/g and 37.6% to 56.5%, respectively. The range for peak viscosity among different varieties was between 804 and 1252 cP. The hardness of starch gels ranged from 21.5 to 32.3 g. African Tall and Early Composite showed higher swelling power, peak, trough, breakdown, final and setback viscosity, and lower ΔH_gel and range of gelatinization. Pearson correlations among various properties of starches were observed. Gelatinization onset temperature (T_o) was negatively correlated to peak-, breakdown-, final- and setback viscosity (r = −0.809, −0.774, −0.721 and −0.686, respectively, p < 0.01) and positively correlated to pasting temperature (r = 0.657, p < 0.01). ΔH_gel was observed to be positively correlated with T_o, peak gelatinization temperature and (T_p) and gelatinization conclusion temperature T_c (r = 0.900, 0.902 and 0.828, respectively, p < 0.01) whereas, it was negatively correlated to peak- and breakdown- (r = −0.743 and −0.733, respectively, p < 0.01), final- and setback viscosity (r = −0.623 and −0.611, respectively, p < 0.05). Amylose was positively correlated to hardness (r = 0.511, p < 0.05) and gumminess (r = 0.792, p < 0.01) of starch gels.     

损伤淀粉含量对米粉理化性质的影响

采用不同粉碎方法得到损伤淀粉含量不同的米粉,研究了损伤淀粉含量对米粉性质的影响。结果表明随着损伤淀粉含量的增加,米粉的总直链淀粉没有明显差异,可溶性直链淀粉和溶解度显著升高,溶胀度变化不大而透明度则显著降低。快速黏度分析(RVA)表明糊化温度由89.2℃降低到86.2℃,回生值由89.58 RVU降低到59.33 RVU,峰值黏度由139.29 RVU降低到85.08 RVU,谷值黏度由103.67 RVU降低到49.04 RVU,末值黏度由180.67 RVU降低到108.38 RVU。损伤淀粉含量9.05%米粉的衰减值最低。糊化后米粉凝胶的硬度和弹性显著降低。     

Viscosity,Swelling and Starch Leaching During the Early Stages of Pasting of Normal and Waxy Rice Starch Suspensions Containing Different Milk Protein Ingredients

The effects of three milk protein ingredients, sodium caseinate (NaCAS), whey protein isolate (WPI) and skim milk powder (SMP), on the swelling and leaching behaviour of normal and waxy rice starch solutions, during the early stages of pasting, were investigated. It was found that the swelling onset temperature for both starches was increased by NaCAS and SMP but was not affected by WPI. Furthermore, onset temperature determined by the swelling measurements was lower than the onset temperature determined from viscosity measurements. However, the calculated viscometric onset temperature, using the Maron‐Pierce equation and the results of the swelling measurements, was found to be in very good agreement with the measured viscometric onset temperature. This study also showed that the quantity of leached polysaccharides during the early stages of starch pasting was very small, indicating that significant leaching of polysaccharides during pasting primarily occurs after the break‐up of the sheared starch granules.     

Influence of Pine Nut (Pinus koraiensis) Oil Fractions on Physicochemical Properties of Rice Starch Solutions

The physicochemical properties of rice starch suspensions effected by interactions with pine nut oil fractions were investigated. Oil fractions (crude pine nut oil, glycolipid, nonpolar lipid, gums, and degummed oil) from pine nut (Pinus koraiensis) were prepared by solvent extraction and addition of boiling water. The influence of the fractions on the physicochemical properties of rice amylose solution (5%, w/w) was determined by measuring the complexing index, absorbance ratio (630/520 nm), colour, rheological characteristics, and microscopic structure at various concentrations. Their effect on rice starch swelling power was also determined. The glycolipid fraction had the highest complexing index with rice amylose. Rice amylose solutions containing the glycolipid fraction exhibited greater pseudoplastic fluid (n<0.7) behaviour, higher colour difference values, and lower absorption ratios (1.64‐1.48) than did those containing other fractions. Hydrated oil fraction (gums) complexed with amylose only poorly, if at all, but amylose solutions containing them had rheological properties similar to those containing the glycolipid fraction. The addition of oil fractions increased the swelling power value compared to the control.     

Gelatinization and Pasting Properties of Waxy and Non‐waxy Rice Starches

Gelatinization and pasting properties of diverse rice types grown in two locations were examined by differential scanning calorimetry (DSC) and rotational rheometry, respectively. The data were compared to previously reported molecular starch properties for these samples: specifically, amylose content, starch molecular weight (M_w), and amylopectin side‐chain‐length distributions. Significant correlations were observed between amylose content, starch M_w, and the weight degree of polymerization of the long side chains of amylopectin F₁(DP_w) and many of the gelatinization and pasting properties measured. Higher amylose content corresponded with increased gelatinization onset (T_o) and peak temperatures (T_p), pasting onset and peak temperatures, and decreased peak and trough viscosity. Starch M_w correlated negatively with T_o, T_p, pasting onset, and peak temperature and positively with peak, trough, final, and breakdown viscosity. Amylopectin with DP_w 59‐78 of F₁(DP_w) correlated with increased T_o, T_p, pasting onset and peak temperature, and decreased peak, trough, final and breakdown viscosity. Pasting properties were also somewhat related to DP_w 21 of shorter side chains of amylopectin (F₂(DP_w)). Significant correlations between F₂(DP_w) and peak, final, and breakdown viscosity were observed (r = −0.447*, −0.391*, −0.388*, peak, final, and breakdown viscosity, respectively).     

Effect of Ultrasonic Treatment on the Physicochemical Properties of Maize Starches Differing in Amylose Content

Normal maize, waxy maize and amylomaize V starches were treated at a moisture content of 70% by ultrasonic treatment. The results showed that the surface of normal and waxy maize starches was porous after treatment and a fissure could be clearly observed in the surface of amylomaize V starch. Ultrasonic treatment did not change the X‐ray pattern of the three maize starches. The swelling power (amylomaize V (B‐type) > normal maize > waxy maize (A‐type)) and solubility (amylomaize V > normal maize > waxy maize), the syneresis of amylomaize V starch and the gelatinization transition temperatures of the three starches increased on this treatment. Ultrasonic treatment decreased the syneresis of normal and waxy maize starches, the enthalpy of gelatinization (amylomaize V > waxy maize ≈︂ normal maize) and the gelatinization temperature range (amylomaize V > normal maize ≈︂ waxy maize) of all starches. A drop in viscosity of all three starches was observed and the viscosity patterns of three starches remained unchanged after ultrasonic treatment. The data showed that ultrasonic treatment degraded preferentially the amorphous regions and more easily attacked linear amylose than highly branched amylopectin.     

Thermal and Pasting Properties of Microwaved Corn Starch

Corn starch with 15–40% moisture was irradiated at 0.17 or 0.5 W/g for 1 h using the sophisticated Ethos 1600 microwave apparatus that accurately controls temperature and wattage. Temperature of irradiated starch was measured during microwaving. Thermal and pasting properties were studied on dehydrated starch after microwave irradiation. Temperature increases were greatest during the first 10 min for starch at all moisture contents at both microwave power levels. Starch irradiated at 0.17 W/g had a temperature below onset gelatinization temperature (T_o) after 1 h. Higher temperatures were observed for starch with higher moisture content and microwaved at 0.5 W/g. Compared to native starch, starch with 15–40% moisture had higher T_o (measured using differential scanning calorimetry) and with 35–40% moisture had higher peak gelatinization temperature and lower enthalpy change of gelatinization. All paste viscosity parameters measured by the Rapid Visco Analyser were reduced and pasting temperature was elevated for starch irradiated at 0.5 W/g compared to native starch.     

Crystallinity and Rheological Properties of Pregelatinized Rice Starches Differing in Amylose Content

Three rice starches with different amylose contents (Glutinous: 1.4%, Jasmine: 15.0% and Chiang: 20.2%) were pregelatinized in a double drum dryer at 110, 117 and 123°C. Starch crystallinity was determined by X‐ray diffractometry and Fourier transform infrared (FTIR) spectrometry. Rheological properties were assessed by a Rapid Visco Analyser (RVA) and rheometer. Pregelatinized starches obtained from Glutinous (PGS) and Jasmine rice (PJS) gave an RVA pasting profile with cold peak viscosity. At drum temperature 110°C, PGS and PJS showed X‐ray patterns that were indicative of amorphous structures. However, pregelatinized Chiang rice starch (PCS) exhibited RVA hot peak viscosity and the presence of an amylose‐lipid complex with remaining granule structure. The PCS had a lower water absorption index (WAI) and water solubility index (WSI) than PJS and PGS. After pregelatinization at increased drum temperature (117, 123°C), the PGS had a lower WAI, whereas PCS showed an opposite trend indicating lower degree of granule disruption. In addition, the cold peak viscosity of PGS and PJS decreased with increasing drum temperature. For all drum temperatures, the apparent viscosity at 25°C for PGS and PJS decreased with increasing shear rate, indicating shear‐thinning behavior.     

Crystallinity and Pasting Properties of Freeze‐Thawed High Amylose Maize Starch

Native and defatted high amylose (about 70%) maize starch gels were freeze‐dried or repeatedly freeze‐thawed, and the effects of the treatments on the crystallinity, pasting viscosity, and resistance to digestive enzymes of the dried starch were examined. Both native and defatted starches showed a B‐type crystal structure in the X‐ray diffractogram, but the crystallinity was decreased by repeating the freeze‐thawing cycle. In the DSC thermogram, the freeze‐thawed starches exhibited two endothermic transitions in the temperature ranges of 90—110 °C and 130—160 °C, representing amyloselipid complexes and amylose‐amylose double helix crystals, respectively. By defatting, the melting enthalpy for the amylose double helices was increased, indicating that the residual lipids inhibited the amylose crystal formation. Ice crystals in the starch gel matrix became smaller and the ice cell membrane became thinner as freeze‐thawing was repeated. The freeze‐dried or freeze‐thawed starch powders swelled to a paste by heating in water as did typical granular starch, but the setback by cooling was significantly high due to the rapid retrogradation of leached amylose. By the treatments, the resistance of the starch to digestive enzymes was also raised. The defatted starches displayed greater paste viscosity and resistance to digestive enzymes than the native starches. But the overall viscosity was decreased as the number of freeze‐thawing cycles increased.     

稻米的凝胶特性研究

用拉伸应力法对不同糊化时间、含水量和糊化度的大米的凝胶特性进行了研究。建立了弹性模量与拉伸时间的数学模型。弹性模量具时变性,与拉伸时间成倒数关系。糊化时间和加水量对凝胶断裂强度的响应面分析表明,在糊化时间为7．631min,加水量为56．15％,断裂强度有极小值4．79gf/mm^2。糊化度、糊化时间和加水量都与时间系数成负相关。     

Formation of Resistant Starch in Corn Starch and Estimation of its Content from Physicochemical Properties

The effect of autoclaving temperatures (100‐120°C) on yields of enzyme‐resistant starch (RS) from normal corn starch and the physicochemical properties of autoclaved‐cooled starches were studied. The RS content increased linearly with increasing autoclaving temperature (R² = 0.993) and the number of autoclaving‐cooling cycles at an autoclaving temperature of 120°C. The effect of the number of autoclaving‐cooling cycles was more pronounced than that of temperature. The swollen starch weight measured at 60°C slightly increased as the RS content increased, and then drastically decreased with the continous increase of the RS content (R² = ‐0.969). As the RS content increased, all parameters of Rapid Visco Analyser (RVA) viscosity except breakdown decreased. Log RVA peak viscosity showed a negative correlation with the RS content (R² = ‐0.986). The enthalpy in the differential scanning calorimetry (DSC) endotherm corresponding to the transitions of RS linearly increased as the RS content increased (R² = 0.988). The RS content of the heat‐treated starch estimated from the relationship between RS content and swollen starch weight at 60°C, log RVA peak viscosity or DSC enthalpy was in good agreement with that determined with the standard method.     

糙米直链淀粉含量对其面包质构和体外消化性质影响研究

将不同直链淀粉含量的5种糙米磨粉,添加20%谷朊粉制作糙米面包,以比容、质构及体外消化性质为指标,研究糙米直链淀粉含量对面包品质的影响。结果表明,5种糙米直链淀粉质量分数范围在15.96%~21.88%之间。不同的糙米面包比容在2.53以上,直链淀粉质量分数大于19%时,糙米面包硬度、黏性、耐咀性显著提高。随着糙米中直链淀粉含量的增加,糙米面包淀粉体外消化率显著降低,糙米面包中抗性淀粉含量增加。直链淀粉含量19%以上的糙米制作的糙米面包品质较好。     

黄原胶对莲藕淀粉糊化性质及流变与质构特性的影响

为探究亲水性胶体对淀粉性质的影响,将不同比例的黄原胶添加到莲藕淀粉中,研究两者复配后莲藕淀粉的糊化、流变、质构特性及微观结构的变化。结果表明：黄原胶提高了淀粉糊终值黏度、糊化峰值时间并降低淀粉的崩解值和回生值,复配体系有更好的热稳定性和抗老化性。添加不同比例的黄原胶使莲藕淀粉糊的剪切应力不同程度降低,稠度系数K增大,流体指数n降低,加入黄原胶后的淀粉糊仍为假塑性流体,但是具有更好的增稠作用;加入黄原胶提高了淀粉的贮能模量、损耗模量,降低了损耗角正切值tanδ,体系的黏弹性和稳定性增强,其中莲藕淀粉与黄原胶配比为8.0∶2.0（g/g）的复配体系增稠效果、黏弹性、稳定性最好。复配体系的硬度、内聚性、黏着性、咀嚼性降低,弹性略有增大,添加黄原胶形成的凝胶质地更柔软。扫描电子显微镜观察到添加黄原胶后淀粉内部形成更加均匀稳定的结构。     

Effect of Amylose Content on Gelatinization,Retrogradation and Pasting Properties of Flours from Different Cultivars of Thai Rice

Presently, rice cultivars are categorized according to amylose content into three groups: low, medium and high amylose content cultivars. The correlation of amylose content with gelatinization properties, retrogradation, and pasting properties of eleven cultivars of Thai rice were investigated. Rice flour was prepared from milled rice by the wet grinding process. Onset (T_o), peak (T_p) and conclusion (T_c) temperatures of gelatinization, (determined by DSC) were found to be highly positively correlated with amylose levels. This correlation could be used for prediction of amylose content of rice flour. Low amylose starch could also be characterized by low degree of retrogradation (%R). The data obtained from RVA‐viscograms (peak viscosity, breakdown, setback, and pasting temperature) can be used only for characterization of the group of low amylose starches (waxy rice). It was demonstrated that low amylose rice starch provided the highest peak viscosity and breakdown and the lowest setback and pasting temperature among the groups investigated.     

Effects of Compositional and Granular Properties on the Pasting Viscosity of Rice Starch Blends

The changes in swelling power and pasting properties of suspensions of starch blends were studied in dependence on starch composition and at various isothermal temperatures (T_iso). Samples were prepared by mixing rice starches from Kaoshiung Sen 7 (KSS7, a high‐amylose‐content variety) and Taichung waxy 70 (TCW70, a waxy variety). Generally, mixing these starches at a comparable ratio caused significant decrements in overall swelling power, onset temperature of gelatinization or viscosity rise, and final viscosity of hot pastes after 30 min of isothermal stirring. Notable increases in the peak and conclusion temperatures of gelatinization and in the peak viscosity of the pastes were also observed. Generally, all viscosity parameters of the blends showed two linear dependencies on the starch composition, the graphs intersecting at a critical starch composition depending on the parameters concerned. The onset temperature of viscosity increase was related to the volume fraction of swollen granules when they were just closely packed in suspension. The volume fraction of KSS granules was smaller than that of TCW70. In addition, the rate of viscosity increase and the peak viscosity of the starch suspensions could be well described in terms of the swelling power (Q) when Q ≤ ∼27, and depending on the T_iso examined. From the photomicrographs of starch suspensions, the extensive shear‐induced disintegration of TCW70 granules in the co‐existence of rigid KSS7 granules was evident and in turn responsible for the reduced final viscosities of the hot pastes obtained from starch blends.