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.     

Physical Properties of Starch from Cavendish Banana Fruit

Starch was isolated from green Cavendish bananas after sodium hydroxide treatment, and its physical properties as they affected its potential acceptance as a food ingredient were measured and compared with those of corn, waxy corn, waxy corn diphosphate, acetylated waxy corn diphosphate, potato, and tapioca starches. Banana starch granules had a moisture content of 15.5%, an amylose content of 19.5% on a dry weight basis, and were highly irregular in shape and size, with the mode of characteristic length falling at 15 μm. The gelatinization range was 70.1 °C to 74.6 °C. Scanning electron micrography showed that in water the granules underwent surface cracking at 65 °C and progressively greater swelling, deformation, and erosion between 70 °C and 90 °C. At 95 °C, 6% banana starch paste in a Brabender Amylograph had a viscosity four times that of corn starch paste of the same concentration, and viscosity decreased rather slowly with stirring. The paste was somewhat longer than that of corn starch, but appreciably shorter than tapioca starch paste. Gelled banana starch was nearly as strong as corn starch, and also was nearly as opaque and reflective.     

The Reactivity of Native and Autoclaved Starches from Different Origins Towards Acetylation and Cationization

Native potato, waxy corn, corn, wheat, filed pea and lentil starches were autoclaved at 15 psi, 121°C for 1min. Scanning electron micrographs of the native and autoclaved starches showed no changes in granular surfaces and shapes. In all starches, the X-ray intensities at most of the d-spacings between 3-18 Å increased upon autoclaving, being more pronounced in potato. The X-ray patterns of cereals and legumes remained unchanged, while that of tuber (potato) became more cereal-like. Differential scanning calorimetry of the starch samples revealed that autoclaving increased the gelatinization transition temperatures of wheat but decreased that of potato; the changes observed in waxy corn, corn, field pea and lentil starches were very small. The gelatinization enthalpy of all native starches decreased upon autoclaving while the percentage decrease was highly marked in potato. Image analysis of the native and autoclaved starches revealed changes in the granule size distribution patterns. Also, the population mean area of all native starch granules considerably increased upon autoclaving. Acetyl binding capacity, measured at 5% and 10% acetic anhydride addition levels, was higher in autoclaved than in native starches. Furthermore, autoclaving had no influence on starch cationization, studied at 3% and 6% reagent addition levels. The results indicated that the changes in starch molecular organization caused by autoclaving enhanced its reactivity towards acetylation but not cationization.     

Properties of Korean Amaranth Starch Compared to Waxy Millet and Waxy Sorghum Starches

Characteristics of waxy type starches isolated from amaranth, waxy millet and waxy sorghum harvested in Korea were evaluated. Shapes of all starch granules were polygonal or slightly round and the surfaces of waxy millet and waxy sorghum starch granules showed visible pores. Amylose contents of the three starches were between 3.2–6.0% and amaranth starch showed the highest water binding capacity (WBC) (130.7%). The swelling power and solubility of amaranth starch studied at 65.0–95.0°C increased about 13.7‐ and 14.0‐fold, respectively, with increase in temperature. Swelling power of waxy sorghum starch was the highest (72.6 at 95°C) among the starches studied, while amaranth starch had a constant swelling power and its rate of solubility increasely only slowly at temperatures higher than 75°C. From RVA data, initial pasting temperatures of amaranth, waxy sorghum and waxy millet starches were 75.7, 73.3 and 75.2°C, respectively. Peak viscosity, breakdown, and setback from trough of amaranth starch were 68.3, 16.7 and 7.5 RVU, respectively, which were the lowest values among the starches investigated. Using DSC, onset temperature of gelatinization of amaranth starch was 1.5–4.0°C higher than those of waxy sorghum and millet starches, corresponding to the RVA result. The enthalpies of gelatinization of the starches studied in our laboratory were in the range of 8.5–12.7 J/g with decreasing order of waxy sorghum > amaranth > waxy millet starch.     

Clean label starches as thickeners in white sauces. Shearing, heating and freeze/thaw stability

The linear viscoelastic properties and syneresis of freshly prepared and freeze/thawed white sauces prepared with different native starches (corn, waxy corn, potato and rice) at different shearing speeds were studied. Viscosity changes during processing were also measured using a starch pasting cell attached to a rheometer. The freeze/thaw cycle produced a significant increase in the viscous and elastic modulus and the appearance of syneresis in the corn and potato starch sauces, while the waxy corn and rice starch sauces were only slightly affected. Syneresis was significantly reduced upon subsequent heating. Greater shearing speed produced a significant decrease in viscoelasticity. Viscosity profiles revealed that the increase in shearing speed decreased the starch gelatinization temperature and swelling capacity and increased starch breakdown.     

Study on physicochemical characteristics of waxy potato starch in comparison with other waxy starches

The physicochemical properties of wx potato, wx corn, and wx rice starches were examined and compared. wx potato starch displayed the B‐type XRD pattern, whereas wx rice and wx corn displayed the A‐type. Shapes of wx potato starch were oval or slightly round, wx corn and wx rice starch granules were polygonal. AM contents of the three starches were between 1.0 and 1.5%. Rapid viscosity analyzer data showed initial pasting temperatures of wx potato, wx corn, and wx rice starches as 69.6, 75.4, and 76.8°C, respectively, peak viscosity, breakdown, and setback of wx potato starch were 2114, 1084, and 4 mPa s. Using DSC, onset temperature of gelatinization of wx potato starch was 5.5–7.2°C higher than those of wx rice and wx corn starches. The thermal enthalpies of the starches studied in our laboratory were in the range of 0.2268–1.9900 J/g with decreasing order of wx potato > wx corn > wx rice starch.     

Influence of moisture content on the degradation of waxy and normal corn starches acid-treated in methanol

Waxy and normal corn starches with different moisture contents, 5.1-16.9% and 4.8-15.9%, respectively, were prepared and treated in methanol containing 0.36% HCl at 45 °C for 1 h. Recovery of all the treated starches was found to be above 90%. Peak viscosity, gelatinization temperature and enthalpy change of gelatinization of waxy and normal corn starches decreased after treatment and this decrement was found to be more in treated starches having lower initial moisture content. The weight-average degree of polymerization and chain length (CL) of waxy and normal corn starches decreased upon acid-methanol treatment. The decrement ratio of molecular weight of modified starches was found to be negatively correlated with the initial moisture content of the starches. The decrement ratio of normal corn starch was higher than waxy corn starch with similar moisture content of starch. The content and CL of long chain fraction of amylopectin for waxy corn starch slightly decreased after treatment, while no obvious trend was found among starches with different moisture contents. CL of amylose for acid-methanol-treated normal corn starch decreased and this change was found to be higher in starches with lower initial moisture contents. Results demonstrated that the initial moisture content of starch granules strongly influenced the functional properties and degradation of starch treated by acid in methanol.     

Scanning Electron Microscopy Studies of Wheat,Potato and Corn Starch during Gelatinization

The gelatinization of a commercial wheat and potato starch and two types of corn starch (Amaizo Amylomaize VII and Amaizo Amioca Pearl starch) was examined by the scanning electron microscope. Concomitantly, the loss of birefringence in the wheat, potato and corn starch was followed with the light microscope. Swelling and deformation of the starch granules observed in the scanning electron microscope correlated with the loss of birefringence in the light microscope. The gelatinization range of the starches was detected with the scanning scope. Swelling of the wheat starch granules was first observed in the larger A-type granules. Amylomaize VII retained granular structure until approximately 95 °C even though birefringence changes were observed as low as 69°C. Some evidence of structural changes were evident at 83°C. Amioca Pearl underwent structural changes at approximately 68°C and abruptly lost granular structure at approximately 71 °C.     

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 waxy starches under high pressure as influenced by pH and osmolarity: Gelatinization kinetics, final structure and pasting properties

We investigated the influence of pH and osmolarity on the high-pressure-induced gelatinization of waxy corn and waxy rice starches in salt solutions, and the properties of the resulting gels. Gelatinization kinetics, the gel swelling power of starches, their structure and their rheological properties were studied for starch suspensions treated at 500 MPa. Gelatinization took place mostly in the first 15 min of the pressure treatment and both the gelatinization speed and the maximal level of gelatinized starch decreased with increasing osmolarity. pH had a minor influence on gelatinization kinetics differing from one starch to another. The resulting gels appeared as a mix of a gel and starch granules with a higher proportion of native granules with increasing osmolarity. Gel strength and swelling were positively correlated to their proportion of gelatinized starch. Thus, gels with different structures and gelatinization levels can be obtained under pressure depending on pH and osmolarity.     

Lily Starch—An Underutilized and Non-Conventional Source: Properties and Applications

Lily belongs to the genus Lilium of the family Liliaceae. Starch is the main component of lily bulbs which accounts for 53–69% of their dry weight. Lily starch (LS) has B-type X-ray diffraction characterized by a peak at 5.6°, 17°, 22°, and 24°. The swelling and solubility of the LS are significantly higher than rice and corn starches. The gelatinization temperatures of the LS are much lower than maize but higher than wheat and potato starches. The pasting temperature, peak, breakdown, and setback viscosities of lily starches are falling within the range; 66.1–72.7 °C, 1409–3940 cP, 88–1206 cP, and 445–1952 cP, respectively. The range for initial temperature, gelatinization temperature range, and enthalpy for lily starches is also 56.5–64.0 °C, 3.8–10.3 °C, and 3.9–13.9 J g⁻¹, respectively. This review focuses on the recent advances in the understanding of the composition, structure, and properties of lily starches. Furthermore, the limited modification associated with lily starches is also discussed. There is a bold attempt to compare the properties of lily starch with that of the commercial starches of corn and potato.     

天然淀粉的超高压糊化压力研究

在悬浮液浓度为5%(w/v),温度为(20±2)℃时,对8种不同淀粉进行高压处理5 min使淀粉发生糊化,采用X射线衍射测试技术得到了各种淀粉完全糊化的压力:小麦淀粉和木薯淀粉约为500 MPa,玉米淀粉、荸荠淀粉、糯小麦淀粉和糯米淀粉均为550 MPa,糯玉米淀粉约为650 MPa,马铃薯淀粉为750 MPa.     

Application of Differential Scanning Calorimetry to Starch Gelatinization. II. Effect of Heating Rate and Moisture Level

The influence of heating rate on the gelatinization of wheat starch and starch/water ratio on the gelatinization of wheat, maize, waxy maize and amylomaize starches was examined. More rapid heating resulted in a lowering of the onset temperature of gelatinization for wheat starch from 52 °C at 8°C/min to 46 °C at 32 °C/min. A linear relationship was observed between moisture content and gelatinization energy for starch/water ratios between 1 :2 and 2:1. This allowed calculation of the minimum level of water necessary to initiate gelatinization of each starch. These levels were in excess of the water binding capacity for each starch and were 0.45, 0.45, 0.47 and 0.52 g water/g of wheat, maize, waxy maize and amylomaize starches respectively.     

Development and Physicochemical Characterization of New Resistant Citrate Starch from Different Corn Starches

Resistant starch has drawn broad interest for both potential health benefits and functional properties. In this study, a technology was developed to increase resistant starch content of corn starch using esterification with citric acid at elevated temperature. Waxy corn, normal corn and high‐amylose corn starches were used as model starches. Citric acid (40% of starch dry weight) was reacted with corn starch at different temperatures (120–150°C) for different reaction times (3–9 h). The effect of reaction conditions on resistant starch content in the citrate corn starch was investigated. When conducting the reaction at 140°C for 7 h, the highest resistant starch content was found in waxy corn citrate starch (87.5%) with the highest degree of substitution (DS, 0.16) of all starches. High‐amylose corn starch had 86.4% resistant starch content and 0.14 DS, and normal corn starch had 78.8% resistant starch and 0.12 DS. The physicochemical properties of these citrate starches were characterized using various analytical techniques. In the presence of excess water upon heating, citrate starch made from waxy corn starch had no peak in the DSC thermogram, and small peaks were found for normal corn starch (0.4 J/g) and Hylon VII starch (3.0 J/g) in the thermograms. This indicates that citrate substitution changes granule properties. There are no retrogradation peaks in the thermograms when starch was reheated after 2 weeks storage at 5°C. All the citrate starches showed no peaks in RVA pasting curves, indicating citrate substitution changes the pasting properties of corn starch as well. Moreover, citrate starch from waxy corn is more thermally stable than the other citrate starches.     

Amylopectin structure of heat–moisture treated starches

The effects of heat–moisture treatment (HMT; moisture content of 25%, at 100°C for 24 h) on starch chain distribution and unit chain distribution of amylopectin in normal rice, waxy rice, normal corn, waxy corn, normal potato, and waxy potato starches were investigated. After HMT, starch chain distribution (amylose and amylopectin responses) of waxy corn and potato starches were identical to those of untreated starches, whereas the chromatographic response of waxy rice starch showed a slight decrease, but with a slight increase in peak tailing. This result indicated that HMT had no (or very limited) effect on the degradation of amylopectins. Analysis of unit chain distribution of amylopectins revealed that waxy characteristics affected the molecular structure of amylopectin in untreated starches, i.e., the CL of normal‐type starches was greater than that of waxy‐type starches. After HMT, the CL and unit chain distribution of all starches were no different than those of untreated starches. The results implied that changes in the physico‐chemical properties of HMT starches would be due to other phenomena rather than the degradation of amylopectin molecular structure. However, the thermal degradation of amylopectin molecules of waxy starches could occur by HMT at higher treatment temperatures (120 and 140°C).     

Morphology of starch in surimi gels

 The purpose of this work was to study the changes undergone by starch during heat-induced surimi gel preparation either with or without added egg white, and their effects on the structure of gels using light and scanning electron microscopy. Gels were made from SA-grade Alaska pollack (Theragra chalcogramma) surimi with: (1) salt (3%, w/w); (2) salt and waxy corn starch (3% and 5%, respectively w/w); or (3) salt, waxy corn starch and egg white (3%, 5% and 5%, respectively, w/w). Final moisture was adjusted to 73% or 83%. The gels were prepared by prior setting (40°C, 30 min, followed by 90°C, 30 min) or cooking (90°C, 30 min). The prepared gel was frozen and stored at –20°C (±1°C) until analysis. Samples were observed by light and scanning electron microscopy. The results show that the starch granules alter according to the processing conditions, with the predominance of crystalline or amorphous morphology depending upon the availability of heat and water. Large cavities formed in the protein gel matrix during setting can trap water; as a result, water availability is limited for starch to swell and gelatinize even in the high-moisture gel. Received: 13 March 1997     

Assessment of some parameters involved in the gelatinization and retrogration of starch

Factors influencing the formation of resistant starch (RS) during gelatinization and retrogradation were studied in starches and flours from cereals (wheat, corn, rice) and potato. RS obtained using a high-pressure autoclave system varied between 3.94 and 21.21% (rice and potato starches, respectively) similar to the values obtained after gelatinization in a boiling water bath. Except for rice, RS was higher in pure starches than in flours. Stirring during gelatinization yielded more homogeneous products than non-stirred samples. Apparently, gelatinization was unaffected by pH values between 3.5 and 10.5. To obtain optimum RS yields during retrogradation, it was necessary to cool down starch gels prior to freezing, followed by thawing at room temperature and drying at 60°C. These conditions ensure good yields in the formation of RS with potential industrial applications. ©     

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     

Hysteretic Effect of Step by Step Heating on the Restriction of Gelatinization of Legume Starch

The restriction of gelatinization of the legume starches, which were isolated from Phaseolus vulgaris species, was studied in terms of enzymatic digestion, light microscopic observation, measurements of X-ray diffraction, viscosity, swelling power and solubility, when the legume starch slurries were heated in step by step manner at a given rate from moderate temperature up to 90°C. Three legume starches tested showed a remarkable restriction of gelatinization, although these phenomena were not always observed in the legume starch slurry alone. Such restriction of gelatinization, however, was not observed in the waxy starch or starches which contain few amylose fractions. The formation of starch-lipid complex was ruled out as a cause because the defat treatment did not reduce the restricted gelatinization of legume starch and high amylose corn starch. From the data presented, it was suggested that physical modification of starch slurry containing amylose fraction induced the hysteretic, mutual alteration of the starch macromolecules.