Morphological,thermal, rheological and noodle‐making properties of potato and corn starch

A comparison between the morphological, thermal, rheological and noodle‐making properties of corn starch and potato starches separated from five different potato cultivars was made. The granule size and shape of all starches differed significantly. Potato starch granules were comparatively larger than corn starch granules, while the transition temperatures were found to be higher for corn starch. Consistency coefficients and flow behaviour indices measured by back extrusion were higher for potato starches than for corn starch. Stickiness of cooked starch pastes was observed to depend upon their consistency coefficient. The gels made from all potato starches showed higher gel strength than those from corn starch. The gel strength of starches from both corn and potato increased during refrigerated storage. The amylose content, swelling power, solubility and light transmittance values of potato starches were significantly higher than those of corn starch. Noodles made from potato starches had higher cooked weight and cooking loss than corn starch noodles. Texture profile analysis revealed that potato starch noodles also had higher hardness and cohesiveness than corn starch noodles. Hardness of cooked noodles from all starches increased and cohesiveness decreased during storage. Noodles made from starches of higher viscosity exhibited higher hardness and cohesiveness. Textural differences among cooked starch noodles appeared to be associated with morphological, thermal and rheological properties of corn starch and potato starches. © 2002 Society of Chemical Industry     

Starch Noodle Quality as Related to Potato Genotypes

Starch noodles were prepared using potato starch from 8 genotypes, mung bean starch, mung bean-potato starch blends, and sweet potato starch. The cooking quality of noodles from selected potato starches compared well with commercial starch noodles. Of the unblended potato starches, Mainechip exhibited cooking quality similar to commercial starch noodles with respect to cooking loss, cooked weight, and ?rmness. Appearance and texture of starch noodles from three genotypes (E55-35, Mainechip, and Shasta) were evaluated by a trained sensory panel. Noodles made from unblended potato starches had higher glossiness and transparency than those from other starches. Noodles from both un-blended and blended Mainechip starch had the highest press and elasticity.     

三种天然植物淀粉辅料对米粉丝品质特性的影响

以天然绿豆淀粉、玉米淀粉及马铃薯淀粉3种天然植物淀粉为原料,探讨其作为辅料添加对米粉丝蒸煮品质和质构特性的影响。结果表明,添加适量的绿豆淀粉、玉米淀粉或马铃薯淀粉可显著提高米粉丝的烹煮品质及质构特性。绿豆淀粉添加量在0.5~1.5%时加工的米粉丝具有较高的烹煮品质,其添加量在1%时可以显著提高米粉丝的质构特性;玉米淀粉的添加量为6%时米粉丝的烹煮品质较佳,其添加量在4~6%时可显著提高米粉丝的质构特性;马铃薯淀粉的添加量为2%时,米粉丝具有最高的烹煮品质,其添加量在2~3%时可使米粉丝的质构特性显著提高。综合考虑,当绿豆淀粉、玉米淀粉或马铃薯淀粉的添加量分别达到1%、6%和2%时能够显著改善米粉丝的蒸煮和质构品质特性。     

Effects of sodium dodecyl sulphate and sonication treatment on physicochemical properties of starch

Effects of sodium dodecyl sulphate (SDS) and sonication treatment on physicochemical properties of starch were studied on four types of starch, namely, corn, potato, mung bean, and sago. The SDS and sonication treatments caused a significant reduction of protein content for all the starches. The SDS treatment did not cause apparent damage on granular structure but sonication appeared to induce changes such as rough surface and fine fissures on starch granules. The combination of SDS and sonication increased amylose content for all starches. This could be attributed to the removal of surface protein by SDS and structural weakening by sonication which facilitated amylose leaching from swollen starch granule. The X-ray pattern for all starches remained unchanged after SDS treatment, suggesting no complexation of amylose–SDS had occurred. Combined SDS-sonication treatment increased swelling and solubility of corn, mung bean, and potato starch. The treated starches showed significant increase in peak viscosity with reduction in pasting temperature, except for potato starch. Results of the present study indicate the possibilities of exploring SDS and sonication treatments for starch modifications.     

Noodle quality affected by different cereal starches

To investigate the effects of starch characteristics on the quality of noodle making, white salted noodles (WSN) made from reconstituted flours, in which the wheat starch was substituted by different cereal starches, including waxy and non-waxy rice starches, waxy wheat starch and waxy corn starch, were prepared. The rheological properties of raw WSN were mainly influenced by the size of starch granules, where the small starch granules, such as for rice starches, exhibited high amounts of water absorption during dough preparation and a dense packing of starch granules inside a thin gluten-strand network. The rheological properties of cooked WSN were mainly dominated by the amylose content and fine structure of the amylopectin, which resulted in the differences in water absorption and cooking time required for cooked WSN.     

Gelatinization of Sweet Potato,Tania and Yam Tuber Starches

Morphological changes that occur in starch granules of sweet potato, tania and yam tubers from native to cooked states, were studied both by electron microscopy and differential scanning calorimetry. In the first stages of heating, the same event was observed in all samples: a central cavity appeared at hilum level of the starch granules just before granule expansion started. Differences in gelatinization behaviour between these three starches were enhanced by mechanism by which amylose leached out. In the sweet potato starch granules, amylose was released through micropores formed in the starch granules during the phase of expansion whereas in tania starch granules, both micropores and pin-holes were observed. In yam starch granules, amylose escaped only by pin-holes formed across the starch granules. When cooking was achieved, spongy-like structures were observed in cooked sweet potato parenchyma cells while folded gelatinized granules remained in yam. In cooked tania tuber, both types of cell contents were observed. Sweet potato, tania and yam starches presented DSC endotherms at 72.7, 69.9 and 74.4°C with enthalpy change of 13.6, 12.9 and 20.9J/g, respectively.     

Starch noodles: History,classification, materials,processing, structure,nutrition, quality evaluating and improving

Starch noodles, produced from purified starch of various plant sources, are a major category of Asian noodles. This review summarizes the current knowledge on: (1) Definition, naming, history and categories of starch noodles. (2) The morphological, physico-chemical, thermal, rheological characteristics and molecular structure of materials including mung bean starch, pea starch, sweet potato starch, potato starch and corn starch. (3) Processing technology of starch noodles including dropping, extruding and cutting. (4) Structure of starch noodles: it is composed of hydrolysis-resistant crystalline zone, network-like framework and filler mass. (5) Nutrition of starch noodles: it could be evaluated by the digestibility of starch, hydrolysis properties of gelatinized and retrograded starches, hydrolysis property of starch noodles. (6) Quality evaluating of starch noodles: it includes sensory, cooking and texture property. Correlation between the physical properties of starch, processing variables and the sensory, cooking and texture property of starch noodles are summarized. (7) Quality improving for non-mung bean starch noodles: (a) using other materials such as red bean starch, pigeonpea starch, potato starch, sweet potato starch, corn starch, to substitute totally or partly mung bean starch; (b) adding chemically modified starch; (c) adding physically modified starch; (d) biologically treating starch; (e) using additives such as chitosan, polysaccharide gums.     

不同植物来源淀粉之间的理化性质的比较

本研究比较了绿豆淀粉、马铃薯淀粉、红薯淀粉、大米淀粉及玉米淀粉的理化性质,结果如下：绿豆淀粉具有最高的直链淀粉渗滤和胶凝值,并且这两个指标均与表观和总直链淀粉含量呈高度的相关关系。尽管绿豆淀粉具有最高的直链淀粉含量,但它并不显示出热糊稳定性。红薯淀粉在加热过程中具有高的膨润力和峰值黏度、高的崩溃值以及低的离水率,这表明红薯淀粉颗粒在加热时能够自由膨胀,糊的热稳定性差,淀粉的老化速率较低,而大米淀粉则与红薯淀粉相反。五种淀粉具有不同的胶稠度,马铃薯淀粉最高,而大米淀粉最低。离水率与直链淀粉含量不呈现明显的相关关系,因此其值的大小可能受其他因素的影响。     

Effect of cooking time and ingredients on the performance of different starches in white sauces

The effect of white sauce ingredients and increased cooking time at 90 °C on the degree of gelatinization of corn, waxy corn, rice, potato and modified waxy corn starches was studied. The changes in pasting properties, linear viscoelastic properties, and microstructure were determined. In all the native starches in water, a longer cooking time at 90 °C caused greater starch granule swelling and more leaching of solubilized starch polymers into the intergranular space. These effects were more noticeable in the waxy corn and potato starches. The potato starch was the most affected, with complete disruption of the starch granules after 300 s at 90 °C. The microstructural changes which transformed a system characterized by starch granules dispersed in a continuous phase (amylose/amylopectin matrix) into a system with an increase in the continuous phase and a decrease in starch granules were associated with a decrease in system viscoelasticity. The elastic moduli were higher in the sauce than in the starch in water system. However, with the exception of potato starch, the white sauce showed lower viscoelasticity than the starch in water system. The white sauce ingredients decreased the effect of cooking time on the starch gelatinization process, particularly in potato starch.     

甘肃主要杂豆淀粉理化特性分析

以甘肃产三角豌豆、白豌豆、小白芸豆、麻豌豆为材料,采用湿磨法提取淀粉,以玉米、马铃薯及绿豆淀粉为对照,对杂豆淀粉的理化特性进行分析。结果表明：参试杂豆淀粉颗粒多呈卵圆形,偏光十字较明显,多呈“X”形和斜十字形,部分淀粉颗粒呈现明显多脐点现象,平均粒径为21～29μm,其中三角豌豆淀粉的粒径最大而麻豌豆淀粉颗粒最小;淀粉颗粒的结晶类型与绿豆淀粉相同,为C型。其直链淀粉含量远高于玉米淀粉和马铃薯淀粉,且麻豌豆＞小白芸豆＞白豌豆＞三角豌豆淀粉。杂豆淀粉属限制型膨胀淀粉,起糊温度为72.6～78.8℃,且具有较好的热糊和冷糊稳定性,淀粉糊的透明度较高,但凝沉速度均极快,冻融稳定性也都较差。4种杂豆淀粉的理化特性与绿豆淀粉相近,可耐受高温处理,但不宜用于冷冻类食品的生产。     

Starch‐Soybean Oil Composites With High Oil: Starch Ratios Prepared By Steam Jet Cooking

Aqueous mixtures of soybean oil and starch were jet cooked at oil: starch ratios ranging from 0.5:1 to 4:1 to yield dispersions of micron‐sized oil droplets that were coated with a thin layer of starch at the oil‐water interface. The jet cooked dispersions were then centrifuged at 2060 and 10,800×g, the buoyant, high‐oil fractions that rose to the surface were isolated, and the size distributions of the oil droplets were determined. Experiments were conducted with normal dent, waxy, and high‐amylose corn starches; and oleic acid was added during jet cooking to form helical inclusion complexes with amylose. With normal dent and waxy corn starches, nearly all of the oil was recovered in the buoyant layers, and only small amounts of oil were found in the aqueous mid layers and settled solids. Oil droplet diameters in the buoyant layers obtained with normal dent and waxy corn starch ranged from under 5 µm to over 50 µm. Centrifugation at high versus low relative centrifugal force produced only minor differences in the droplet size distributions. With high‐amylose starch, microscopy showed that most of the oil droplets were entrapped within aggregates of sub‐micron particles that were apparently formed from amylose‐oleic acid inclusion complexes when the dispersions were cooled. Droplet sizes increased with an increase in the oil: starch ratio, and decreased when oleic acid was added during jet cooking.     

Microstructural and physicochemical properties of heat-moisture treated waxy and normal starches

Starches from normal rice (21.72% amylose), waxy rice (1.64% amylose), normal corn (25.19% amylose), waxy corn (2.06% amylose), normal potato (28.97% amylose) and waxy potato (3.92% amylose) were heat-treated at 100 °C for 16 h at a moisture content of 25%. The effect of heat-moisture treatment (HMT) on morphology, structure, and physicochemical properties of those starches was investigated. The HMT did not change the size, shape, and surface characteristics of corn and potato starch granules, while surface change/partial gelatinization was found on the granules of rice starches. The X-ray diffraction pattern of normal and waxy potato starches was shifted from B- to C-type by HMT. The crystallinity of the starch samples, except waxy potato starch decreased on HMT. The viscosity profiles changed significantly with HMT. The treated starches, except the waxy potato starch, had higher pasting temperature and lower viscosity. The differences in viscosity values before and after HMT were more pronounced in normal starches than in waxy starches, whereas changes in the pasting temperature showed the reverse (waxy > normal). Shifts of the gelatinization temperature to higher values and gelatinization enthalpy to lower values as well as biphasic endotherms were found in treated starches. HMT increased enzyme digestibility of treated starches (except waxy corn starch); i.e., rapidly and slowly digestible starches increased, but resistant starch decreased. Although there was no absolute consistency on the data obtained from the three pairs of waxy and normal starches, in most cases the effects of HMT on normal starches were more pronounced than the corresponding waxy starches.     

Resistant Starch Derived from Extruded Corn Starch and Guar Gum as Affected by Acid and Surfactants: Structural Characterization

Corn starches with and without guar gum [10% (w/w)] and 2% (w/w) of diacetyl tartaric acid ester of monoglyceride, sodium stearoyl‐2‐lactylate or citric acid, respectively, were extrusion‐cooked in a twin‐screw extruder at 18% moisture, 150 °C and 180 rpm screw speed. The content of resistant starch was determined by sequential enzymatic digestion. The formation of resistant starch in extruded corn starch was strongly affected by the addition of gum and the different food additives. X‐ray diffraction of the extruded starches gave a V diffraction pattern indicating the effect of extrusion cooking and amylose‐lipid complexes. Enzymatic digestion did not affect the V‐structure, which could apparently be attributed to extrusion cooking. Similarly, differential scanning calorimetric thermograms indicated that all isolated resistant starches exhibited endothermic transitions between 71—178 °C signifying a complex formation between amylose and the emulsifiers and possibly the melting of amylose crystallites in the resistant starch. Purification of the isolated resistant starches by size exclusion‐high performance liquid chromatography showed a dependence of molecular weight on the added additives. Results of differential scanning calorimetry and X‐ray diffraction suggest that amylose‐lipid complexes could also be involved in the formation of resistant starch in extruded cornstarch.     

Structures and Physicochemical Properties of Acid‐Thinned Corn,Potato and Rice Starches

The structures and physicochemical properties of acid‐thinned corn, potato, and rice starches were investigated. Corn, potato, and rice starches were hydrolyzed with 0.14 N hydrochloric acid at 50 °C until reaching a target pasting peak of 200—300 Brabender Units (BU) at 10% solids in the Brabender Visco Amylograph. After acid modification the amylose content decreased slightly and all starches retained their native crystallinity pattern. Acid primarily attacked the amorphous regions within the starch granule and both amylose and amylopectin were hydrolyzed simultaneously by acid. Acid modification decreased the longer chain fraction and increased the shorter chain fraction of corn and rice starches but increased the longer chain fraction and decreased the shorter chain fraction of potato starch, as measured by high‐performance size‐exclusion chromatography. Acid‐thinned potato starches produced much firmer gels than did acid‐thinned corn and rice starches, possibly due to potato starch's relatively higher percentage of long branch chains (degree of polymerization 13—24) in amylopectin. The short‐term development of gel structure by acid‐thinned starches was dependent on amylose content, whereas the long‐term gel strength appeared dependend on the long branch chains in amylopectin.     

Chemical composition,digestibility and emulsification properties of octenyl succinic esters of various starches

Octenyl succinate starches are commonly used as emulsifiers and texturizing agents in many food-systems. Rice, tapioca, corn, wheat and potato starches were modified with octenyl succinic anhydride (OSA) at 3% level. Structural characterization, molecular weight, starch digestibility and physical properties of starch granule stabilized emulsions were studied for modified starches. Modified potato (0.022) and wheat (0.018) starches had the highest and lowest degrees of OSA substitution, respectively. For all starches, amylose and amylopectin molecular mass was significantly (P < 0.05) lower for OSA starches. OSA modification may have hydrolyzed the small amylose and amylopectin chains, or caused rearrangement of the starch molecules. Although the starch modification improved emulsification properties, botanical source showed more influence on this parameter. Overall, botanical source had more influence on functional properties than degree of substitution. Further studies on OSA group distribution and fine molecular structure of amylopectin and relationship with functional properties will be important.     

Starch Granule Size Strongly Determines Starch Noodle Processing and Noodle Quality

Chemical compositions, physical properties, and suitability for starch noodle making of different granule size fractions from potato and sweet potato starches were studied. The ash content, amylose content, phosphorus content, gel firmness, and freeze‐thaw stability of small‐size granule fractions(< 20 μm) were significantly different from those of the large‐size granule fractions. The processibility and the qualities evaluated by objective and subjective methods of both dried and cooked starch noodles made from small‐size granule fractions were significantly better than those made from their initial starch preparations and much better than those made from the large‐size granule fractions.     

Studies on Rye Starch Properties and Modification. Part II: Swelling and Solubility Behaviour of Rye Starch Granules

Rye starch shows the typical inhibited swelling behaviour of triticeae starches with an onset of swelling at rather low temperature (50–55°C). Swollen rye starch granules exist as individuals even after swelling at 100°C. The total dispersion of rye starch needs temperatures above 120°C with pressure cooking. On heating of the rye starch suspension preferentially amylose is leached. Defatting of rye starch exhibits no influence on swelling power but results in higher solubility and in increased amylose leaching. The drying procedures applied here resulted in stronger assoziation of the polymer molecules in the starch granule leading to higher swelling temperatures and a reduced solubility. Shiftings of the crystalline/ amorphous-ratio of the starch granules as caused by different drying procedures, had no influence on the results of swelling power investigation but the highest swelling enthalpy as well as Brabender viscosity were exhibited by a sample dried at room temperature. It is proved to be possible to change the swelling behaviour of rye starch to “potato starch type” by slight chemical modification like succination.     

4种不同品种蚕豆淀粉理化性质分析

选取河北崇礼、青海马牙、云南白皮豆、云南透心绿4种高产优质蚕豆品种,对其淀粉的理化性质进行分析研究。结果表明:蚕豆淀粉颗粒呈(椭)圆或不规则球形、表面光滑,粒径在12～32μm,24h沉降积为30～32mL,透明度高于谷物淀粉、低于马铃薯淀粉,蚕豆淀粉一次冻融循环后即开始失水,持水力高于小扁豆和豌豆淀粉。蚕豆淀粉中直链淀粉含量(28%～34%)高于小扁豆和鹰嘴豆淀粉。     

Characterization of Different Starches Oxidized by Hypochlorite

The effects of starch origin (potato, corn, and rice starches) and hypochlorite level (NaOCl, 0.8% and 2% w/w) on the structures and physicochemical properties of oxidized starches were investigated. Carboxyl and carbonyl group contents of oxidized starches increased with increasing NaOCl level, with potato starch having the highest and corn starch having the lowest carboxyl groups content at both NaOCl levels. Oxidation generally reduced the pasting temperature and viscosity of native starches as demonstrated by using a Rapid Visco Analyser. The peak viscosities of oxidized rice and corn starches were higher than those of their native counterparts at 0.8% NaOCl. The morphology of starches was not altered and X‐ray diffraction patterns of all the starches remained unchanged after oxidation. Oxidized starch batters exhibited greater adhesions than did native starch batters, with rice starch batter exhibiting the greatest adhesion. Carbohydrate profiles by high‐performance size‐exclusion chromatography indicated that both amylopectin and amylose were degraded during oxidation. The level of oxidation was largely dependent on the degree of crystallinity of starch and the degree of polymerization of amylose, whereas the adhesion property of oxidized starch was mainly attributed to its granular size and shape.     

Thermal,rheological, and mechanical properties of normal corn and potato starch blends

Native corn and potato starches were mixed in different proportions. Blends presented similar values to potato starch at onset temperature and at ending temperature to corn starch. CS20PS80 blend had the highest values for hardness between blends due to the formation of a three-dimensional network with corn starch granules that act as composite material. Some blends exhibited higher recovery viscosity than native starches, possibly due to interactions. Gelatinization temperature, swelling power, phosphorous content, granule size, and x-ray pattern played an important role in the resulting properties, however, the amylose content did not show influence due to both starches having a similar content.