Amylose-lipid Complexes Research Articles

Physicochemical and crystalline properties of standard maize starch hydrothermally treated by direct steaming

The changes in physicochemical properties of standard maize starch (SMS) by three hydrothermal treatments; DV-HMT (Direct Vapor-Heat Moisture Treatment), RP-HMT (Reduced Pressurized-Heat Moisture Treatment) and DIC (instantaneous controlled pressure drop) were investigated at different processing conditions; steam pressure (SP) varied from 1 to 3bar during 20min. Starch was steamed by direct contact, whose interest was to intensify the heat transfer phenomenon but also the water transfer. The physicochemical changes of SMS depended on process conditions and their extent followed this order: DIC>RP-HMT>DV-HMT. All treatments significantly increased gelatinization temperatures and decreased the enthalpies, confirmed by loss of granules birefringence. From 2bar, the crystalline structure changed from A-type to Vh-type, revealing formation of amylose-lipid complexes during steaming. The results clearly showed that the particle size distribution depends on the melting extent of crystalline structure during treatment. At severe processing conditions the melted fraction increased and more complex aggregates of different sizes have been formed.

Preparation of gluten-free rice spaghetti with soy protein isolate using twin-screw extrusion.

The objective of this study was to investigate the effect of soy protein isolate on functional properties and consumer acceptance of gluten-free rice spaghetti (GFRS) made from rice flour. Dry-milled high-amylose (Chai Nat 1) rice flour was premixed with dry-milled waxy (RD 6) rice flour at a ratio of 90:10 (w/w) with the soy protein isolate (SPI) concentration varying between 0, 2.5, 5.0, 7.5, 10.0%, db. The GFRS formulation was processed using a co-rotating twin-screw extruder up to 95°C with a screw speed of 220rpm, 32% moisture content, and then dried at 40°C. The GFRS samples were analyzed by differential scanning calorimetry (DSC), X-ray diffraction, scanning electron microscopy (SEM) and texture parameters. Increasing SPI decreased the starch retrogradation of GFRS, whereas the enthalpy change of the amylose-lipid complex increased and crystallinity decreased. SEM revealed that the surface of GFRS containing SPI was much more porous than that of GFRS without SPI. The cooked GFRS containing 5.0% SPI showed the best eating quality with increased firmness and tensile strength, and decrease stickiness. The GFRS samples were evaluated on the bases of cooking qualities and sensory evaluation. The results showed that the GFRS containing 5.0% SPI decrease the cooking time from 17.6 to 13.7min and cooking loss from 25.4 to 17.0%. Overall acceptability of cooked GFRS containing 5.0% SPI was the highest among all GFRS samples.

Plant-crafted starches for bioplastics production

Transgenically-produced amylose-only (AO) starch was used to manufacture bioplastic prototypes. Extruded starch samples were tested for crystal residues, elasticity, glass transition temperature, mechanical properties, molecular mass and microstructure. The AO starch granule crystallinity was both of the B- and Vh-type, while the isogenic control starch was mainly A-type. The first of three endothermic transitions was attributed to gelatinization at about 60°C. The second and third peaks were identified as melting of the starch and amylose-lipid complexes, respectively. After extrusion, the AO samples displayed Vh- and B-type crystalline structures, the B-type polymorph being the dominant one. The AO prototypes demonstrated a 6-fold higher mechanical stress at break and 2.5-fold higher strain at break compared to control starch. Dynamic mechanical analysis showed a significant increase in the storage modulus (E′) for AO samples compared to the control. The data support the use of pure starch-based bioplastics devoid of non-polysaccharide fillers.

Effects of gamma irradiation on physicochemical properties of native and acetylated wheat starches

Effects of gamma irradiation on the physicochemical and crystalline properties of the native and acetylated wheat starches were investigated. Peak, hot paste, cool paste and setback viscosities of both native and acetylated wheat starches decreased continuously and significantly with the increase of the irradiation dose, whereas breakdown viscosity increased after irradiation. However, gamma irradiation only exerted slight effects on thermal and retrogradation properties of both native and acetylated wheat starches. X-ray diffraction and fourier transform infrared spectroscopy revealed that acetylation modification had considerable effects on the molecular structure of wheat starch, and the crystallinity of both untreated and acetylated starches increased slightly with the increase of irradiation dose. However, the V-type crystallinity of amylose-lipid complex was not affected by gamma irradiation treatments with doses up to 9kGy.

In-vitro digestibility, rheology, structure, and functionality of RS3 from oat starch

Starches isolated from three different varieties of oat were modified with dual autoclaving-retrogradation treatment to make modified food starches with high contents of type 3 resistant starch (RS3). FT-IR spectroscopy showed increase in the ratio of intensity of 1047cm−1/1022cm−1 on treatment. Morphology of the oat starches changed into a continuous network with increased values for onset temperature (To), peak temperature (Tp), and conclusion temperature (Tc). XRD showed an additional peak at 13° and increase in peak intensity at 20° inclusive of the major X-ray diffraction peaks which reflects formation of amylose–lipid complex from dual autoclaving-retrogradation cycle. Peaks at 13° and 20° are the typical peaks of the V-type pattern. Rheological analysis suggested that retrogradated oat starches showed shear thickening behavior as revealed from Herschel-Bulkely model and frequency sweep.

Aging of low and high amylose rice at elevated temperature: Mechanism and predictive modeling

The objective of this research was to study the changes in physicochemical properties of rice during elevated temperature storage. Paddy of three rice cultivars with low amylose content (9–11%) and the other three with high amylose content (23–25%) was stored at 39.2 °C and 43.1% relative humidity up to 31 weeks. Drastic changes in moisture content and some parameters representing cooking qualities, cooked rice texture and pasting properties occurred during the first four weeks of aging. At similar aging time, low amylose rice had higher adhesiveness, peak viscosity and breakdown, but had lower pasting temperature than high amylose rice. Time-dependent change in adhesiveness and pasting temperature was predicted by fractional conversion model (0.60 ≤ R2 ≤ 0.94). Difference among rate constant values of the data from low and high amylose rice was found. Proportion of high molecular weight proteins (>225 kDa) tended to increase over time. However, enthalpy of amylose-lipid complex melting fluctuated during storage. Changes in protein molecular weight pattern could thus be key mechanism of rice aging at elevated temperature. NIR-based predictive models for minimum cooking time, adhesiveness, pasting temperature, peak viscosity, and breakdown of rice samples were established (R2 of calibration ≥ 0.81; R2 of validation ≥ 0.87).

Influence of Acid Treatment on Physicochemical Properties of Aged Rice Flour

This study investigated the influence of citric acid and ascorbic acid solutions (0.0–0.9% w/w) on the physicochemical properties of 12 month aged rice flour (aged) using 0.7 month rice flour (fresh) as the reference. The results showed that rice storage did not affect the chemical composition. However, 12 month aged rice flour showed an increase in formation of disulfide bonds and amylose-lipid complexes which could restrict starch granules from swelling during gelatinization. Moreover, 12 month aged rice flour showed an increase in gelatinization temperature and enthalpy. Acid treatment did not break the formed disulfide bond but reduced the protein content in the acid-treated 12 month aged rice flour producing a significant increase in granular swelling and thus increased peak viscosity (p ≤ 0.05) but caused a reduction in retrogradation. The excess concentration (0.9% w/w acid solution) induced granule rupture. Aging of rice also affected the textural properties of freeze-thaw gels, increasing the hardness value but this was reduced by the addition of acids.

Effects of fatty acids with different degree of unsaturation on properties of sweet potato starch-based films

The effect of saturated and unsaturated fatty acids on sweet potato starch and sweet potato starch-based films was studied. Three fatty acids varying in degree of unsaturation were used in the preparation of sweet potato starch-based films; i.e. stearic acid (C18:0), oleic acid (C18:1) and linoleic acid (C18:2). The stearic acid is more strongly bound with amylose than oleic acid and linoleic acid. In differential scanning calorimetry thermograms, both of the sweet potato starch-saturated fatty acid and sweet potato starch-unsaturated fatty acid composites exhibited the melting peak of amylose-lipid complex. The amylose-linoleic acid complex peak was unapparent compared with stearic acid and oleic acid. X-ray diffraction showed that the scattering intensity of amylose-lipid complex decreased with increasing unsaturation. Scanning electronic microscope indicated that the surface of the films became smooth after addition of fatty acids. The sweet potato starch-saturated fatty acid composites films exhibited higher tensile strength, lower elongation at break and lower water vapor permeability than those of the sweet potato starch-unsaturated fatty acid composite films.

Freeze-thaw stability of rice starch modified by Improved Extrusion Cooking Technology

This study aimed to explore freeze-thaw (FT) stability of rice starch modified by Improved Extrusion Cooking Technology (IECT). FT stability of IECT-modified rice starch was investigated and compared with native one. Syneresis and SEM analysis showed that IECT-modified rice starch had better FT stability than native starch. Furthermore, IECT-modified rice starch had less significant changes in the rheological parameters during the FT cycles than the native starch. XRD and iodine binding analysis demonstrated that IECT treatment inhibited the association of rice starch, especially amylose retrogradation. Additionally, the peak at around 20° was detected in XRD patterns of IECT-modified rice starch, which confirmed the formation of amylose-lipid complex during the IECT treatment. These results suggested that the IECT treatment could improve FT stability of rice starch, which was ascribed to inhibition of starch retrogradation by IECT.

Characteristics of starch separated from coarse and fine flour fractions obtained from hard, medium‐hard, and soft Indian wheat cultivars

Starches from coarse flour (CF) and fine flour (FF) fractions obtained from flours milled from fifteen different wheat cultivars with varying hardness index were evaluated for granules‐size distribution, pasting and thermal properties. Grain hardness index of softer, medium‐hard and hard wheat cultivars ranged from 66 to 72, 74 to 79, and 80 to 90, respectively. The amylose content of starch from softer wheat cultivars was significantly lower than that from medium‐hard and hard wheat cultivars. Starches from soft wheat cultivars had a greater proportion of granules of sizes <5 μm, 5–15 μm, and 15–25 μm. The swelling power (SP) was positively correlated with granules of >25 μm and negatively with granules between 5 and 25 μm size. The SP of starches from softer cultivars was higher due to a higher proportion of large‐size granules (>25 μm) and lower proportion of amylose content. The mean transitions temperature of starch from FF was higher and the peak viscosity was lower than that from CF. The enthalpy of gelatinization and melting of amylose–lipids complexes during heating and enthalpy of association of amylose–lipids complexes during cooling was higher for starches from cultivars with lower hardness index than those from higher hardness index. Starches from cultivars with lower grain hardness showed lower peak viscosity and vice versa and this was observed to be negatively correlated with the proportion of small granules (0–15 μm).

Effect of fat type in baked bread on amylose-lipid complex formation and glycaemic response.

The formation of amylose-lipid complexes (ALC) had been associated with reduced starch digestibility. A few studies have directly characterised the extent of ALC formation with glycaemic response. The objectives of this study were to investigate the effect of using fats with varying degree of saturation and chain length on ALC formation as well as glycaemic and insulinaemic responses after consumption of bread. Healthy men consumed five test breads in a random order: control bread without any added fats (CTR) and breads baked with butter (BTR), coconut oil (COC), grapeseed oil (GRP) or olive oil (OLV). There was a significant difference in glycaemic response between the different test breads (P=0·002), primarily due to COC having a lower response than CTR (P=0·016), but no significant differences between fat types were observed. Insulinaemic response was not altered by the addition of fats/oils. Although BTR was more insulinotropic than GRP (P<0·05), postprandial β-cell function did not differ significantly. The complexing index (CI), a measure of ALC formation, was significantly higher for COC and OLV compared with BTR and GRP (P<0·05). CI was significantly negatively correlated with incremental AUC (IAUC) of change in blood glucose concentrations over time (IAUCglucose) (r -0·365, P=0·001). Linear regression analysis showed that CI explained 13·3 % of the variance and was a significant predictor of IAUCglucose (β=-1·265, P=0·001), but IAUCinsulin did not predict IAUCglucose. Our study indicated that a simple way to modulate glycaemic response in bread could lie in the choice of fats/oils, with coconut oil showing the greatest attenuation of glycaemic response.

Physicochemical and rheological properties of starch and flour from different durum wheat varieties and their relationships with noodle quality.

Starch and flour properties of different Indian durum wheat varieties were evaluated and related to noodle-making properties. Flours were evaluated for pasting properties, protein characteristics (extractable as well as unextractable monomeric and polymeric proteins) and dough rheology (farinographic properties), while starches were evaluated for granule size, thermal, pasting, and rheological properties. Flour peak and final viscosities related negatively to the proportion of monomeric proteins but positively to that of polymeric proteins whereas opposite relations were observed for dough rheological properties (dough-development time and stability). Starches from varieties with higher proportion of large granules showed the presence of less stable amylose-lipids and had more swelling power, peak viscosity and breakdown viscosity than those with greater proportion of small granules. Noodle-cooking time related positively to the proportion of monomeric proteins and starch gelatinization temperatures but negatively to that of polymeric proteins and amylose content. Varieties with more proteins resulted in firmer noodles. Noodle-cohesiveness related positively to the proportion of polymeric proteins and amylose-lipids complexes whereas springiness correlated negatively to amylose content and retrogradation tendency of starches.

Synergistic maltogenic α-amylase and branching treatment to produce enzyme-resistant molecular and supramolecular structures in extruded maize matrices

From a nutritional perspective, extruded products and ingredients are characterised by a fast digestion rate. In this study, the effect of an enzymatic treatment with branching enzyme (B) and a combination of branching enzyme and maltogenic α-amylase (BMA) on the formation of resistant molecular and supramolecular structures that attenuate the starch digestion properties of maize extruded flours was studied. Moreover, two solvents of different extractability towards sugars (water and ethanol) were employed during treatment. The total carbohydrate release during the enzymatic treatment suggested that extruded flours had a great susceptibility to be modified by the enzymes. The enzymatic treatment itself affected the formation of resistant supramolecular structures on extruded flours by increasing: 1) the long linear amylose chains susceptible to retrograde; 2) the level of short-range molecular order, typical from conformational ordering of amylose or amylopectin side chains; 3) and the amylose-lipid complexes. In particular, the combination of B and MA affected the fine structure of amylopectin in extruded flours, increasing the number of branching points and the ratio of short chains to longer chains. In addition, the combined BMA treatment increased the amount of panose and isomaltotriose in extruded maize flours. Nevertheless, all results were constrained by the type of solvent used in the washing step. In this regard, ethanol was more efficient in terms of keeping isomaltooligosacharides and forming amylose–ethanol complexes, whereas water removed maltose and kept higher the amount of long linear amylose chains and the ratio of short chains to longer chains in amylopectin of extruded flours.

Hydrothermal modification of wheat starch. Part 2. Thermal characteristics of pasting and rheological properties of pastes

Water suspensions of starch (with the concentration of 8 g/100 g) were prepared in a measuring vessel of a Brabender viscograph and heated to temperatures of 74, 76.5, 79, 81.5, 84, 86.5, 89, 91.5 or 94 °C under continuous stirring. The resultant solution was cooled and frozen, and then defrosted. Thermal characteristics of re-pasting, rheological properties of produced pastes, starch solubility in water and swelling power were determined.The heating and freezing of the wheat starch suspension induced changes in its properties, with tendency and extent of these changes depending on temperature of pre-heating. The thermal characteristics of the analyzed starches revealed three peaks that corresponded to transitions proceeding during solubilization of retrograded amylopectin and retrograded amylose and solubilization of amylose–lipid complexes. Retrogradation of amylose induced by starch pre-heating followed by its freezing affected also the consistency coefficient and yield stress of the pastes formed by the analyzed starches. Values of these rheological parameters were higher at higher temperatures of pre-heating, compared to the pastes prepared from native starch, and were changing accordingly to the determined second order polynomial function. Amylose retrogradation occurring during the production of starch preparations diminished their solubility in water and increased their swelling power compared to native starch.

Development of ready‐to‐eat rice starch‐based puffed products by coupling freeze‐drying and microwave

SummaryThe rice starch mixtures with varying amylose contents (AC) of 0.12–19.00% weight were prepared by mixing waxy and nonwaxy rice starches. The 5% rice bran oil shortening was added in the starch paste. After gelatinisation, thin slabs of starch pastes were aged at 4 °C for 24 h. The aged slabs were dried by freeze‐drying to obtain 25% moisture content. A microwave oven set to 600 J s−1 for 90 s was then used for puffing. The crucial factors affecting the snack purchase were texture and nutrition. The relative crystallinity and retrogradation enthalpy (∆Hr) of freeze‐dried pellets increased with increasing the AC. From using a differential scanning calorimeter (DSC), endotherms of pellets were shown only when AC &gt; 0.12%. An amylose–lipid complex was shown in pellets with AC ≥ 9.00%. Relationships between the AC and all puffed product properties were linear. Increasing AC provided greater hardness, fracturability, bulk density, but lower expansion ratio. From the sensory evaluation, the panellists preferred the puffed products with 9.00% AC. Increasing the AC gave higher crispness, hardness, brittleness, air cell opacity and density, but resulted in less puffiness. Thus, the microwave drying has the potential to puff a healthy expanded snack but giving the desirable properties depends on AC.

Pysicochemical properties of Tibetan hull-less barley starch

Objectives of this study were to (1) determine the starch physicochemical properties of two commercial Tibetan hull-less barley varieties, Beiqing (BQ) and Kangqing (KQ); and (2) understand the relationship between unique properties of the starches, their structures, and impacts of growing conditions. The BQ barleys were grown at a location with lower temperature and less rainfall compared with the KQ barleys. The BQ starches showed significantly lower onset-gelatinization temperature (54.1–54.9°C), larger gelatinization-temperature range (9.4–10.6°C), and higher peak-viscosities (138.9–153.9RVU) than the KQ starches (55.1–56.1°C, 7.4–8.8°C, and 63.4–64.7RVU, respectively). After a treatment with 2% sodium-dodecyl-sulphate solution, the KQ starches showed substantially greater increases in peak viscosities than the BQ starches. Annealing of starch and enhanced amylose–lipid complex formation, resulting from higher growing temperature during the development of the KQ starches, likely contributed to the differences in thermal and pasting properties between the BQ and KQ starches.

Overcoming hydrolysis of raw corn starch under industrial conditions with Bacillus licheniformis ATCC 9945a α-amylase.

α-Amylase from Bacillus licheniformis ATCC 9945a (BliAmy) was proven to be very efficient in hydrolysis of granular starch below the temperature of gelatinization. By applying two-stage feeding strategy to achieve high-cell-density cultivation of Escherichia coli and extracellular production of BliAmy, total of 250.5 U/mL (i.e. 0.7 g/L) of enzyme was obtained. Thermostability of amylase was exploited to simplify purification. The hydrolysis of concentrated raw starch was optimized using response surface methodology. Regardless of raw starch concentration tested (20, 25, 30 %), BliAmy was very effective, achieving the final hydrolysis degree of 91 % for the hydrolysis of 30 % starch suspension after 24 h. The major A-type crystalline structure and amorphous domains of the starch granule were degraded at the same rates, while amylose-lipid complexes were not degraded. BliAmy presents interesting performances on highly concentrated solid starch and could be of value for starch-consuming industries while response surface methodology (RSM) could be efficiently applied for the optimization of the hydrolysis.

Physicochemical and Thermal Properties of Extruded Instant Functional Rice Porridge Powder as Affected by the Addition of Soybean or Mung Bean.

Legumes contain protein, micronutrients, and bioactive compounds, which provide various health benefits. In this study, soybean or mung bean was mixed in rice flour to produce by extrusion instant functional legume-rice porridge powder. The effects of the type and percentage (10%, 20%, or 30%, w/w) of legumes on the expansion ratio of the extrudates were first evaluated. Amino acid composition, color, and selected physicochemical (bulk density, water absorption index, and water solubility index), thermal (onset temperature, peak temperature, and transition enthalpy), and pasting (peak viscosity, trough viscosity, and final viscosity) properties of the powder were determined. The crystalline structure and formation of amylose-lipid complexes and the total phenolics content (TPC) and antioxidant activity of the powder were also measured. Soybean-blended porridge powder exhibited higher TPC, 2,2-diphenyl-1-picrylhydrazyl radical scavenging capacity, ferric reducing antioxidant power, amino acid, and fat contents than the mung bean-blended porridge powder. Incorporating either legume affected the product properties by decreasing the lightness and bulk density, while increasing the greenness and yellowness and the peak temperature and transition enthalpy. Expansion capacity of the extrudates increased with percentage of mung bean in the mixture but decreased as the percentage of soybean increased. Amylose-lipid complexes formation was confirmed by X-ray diffraction analysis results. Addition of soybean or mung bean resulted in significant pasting property changes of the porridge powder.

Effect of the ways of adding stearic acid on properties of sweet potato starch and sweet‐potato‐starch‐based films

Starch‐fatty acid composites were prepared using sweet potato starch (SPS) and stearic acid (SA). The SA was added into the starch system by employing two different ways; i.e., either prior to heating (Method I) or after heating (Method II). The ways of adding SA changed the SPS pasting characteristics as determined by Rapid Viscosity Analyzer (RVA). In differential scanning calorimetry (DSC) thermograms, both of the composites exhibited a new peak which was regarded as the melting peak of amylose–lipid complex. Scanning electronic microscope (SEM) images indicated that the quantity of intact starch granules decreased (Method I), while the starch granules in the composite prepared by Method II remained the intact morphology. The composite prepared by Method I exhibited lower relative crystallinity than their counterparts. Compared with the control film, the light transmission of the films prepared by Method I showed a decrease of 10.1%, while the films prepared by Method II exhibited a decrease of 5.1%. The films prepared by Method II had better moisture barrier properties than the films prepared by Method I. The films prepared by Method II showed higher tensile strength and elongation at break values compared with the films prepared by Method I.

Composition and thermodynamic properties of starches from facultative wheat varieties

Effects of wheat variety and time of sowing on chemical composition and thermodynamic properties of starches isolated from grains of three facultative wheat varieties, which are spring varieties that can be grown either as winter or as spring ones, were estimated. Contents of proteins, lipids, amylose and phosphorus in starch granules as well as fatty acid profiles of surface lipids were determined. For each of the three wheat varieties, percentages of starch surface proteins and lipids (free and adsorbed on the surface of starch granules, FL and SSL) and gelatinization parameters of the isolated starches were significantly affected by sowing time. The impact of FL and SSL levels on starch gelatinization parameters and forms of amylose-lipid (AML) complexes was assessed by the differential scanning calorimetry (DSC). Spring-sowing of three tested wheat varieties resulted in reduced susceptibility to gelatinization of starches isolated from their grains, compared to starches derived from the winter-sown counterparts, due to higher percentages of both FL among total surface starch lipids (TSSL) and unsaturated fatty acids contained in TSSL as well as stronger interactions between surface lipids and proteins. The higher FL percentages among TSSL in starches from the spring-sown crops resulted in 1.8–3.8-fold higher percentages of AML complexes formed during gelatinization, compared to the winter-grown counterparts. During heating, these complexes were more prone to restructurization from the amorphous to stable crystalline form than AML complexes contained in the gelatinized starches from the winter-sown facultative wheat varieties.