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.     

Slowly digestible starch from heat-moisture treated waxy potato starch: Preparation,structural characteristics,and glucose response in mice

Heat-moisture treatment (HMT) was optimised to increase the formation of slowly digestible starch (SDS) in waxy potato starch, and the structural and physiological properties of this starch were investigated. A maximum SDS content (41.8%) consistent with the expected value (40.1%) was obtained after 5 h 20 min at 120 °C with a 25.7% moisture level. Differential scanning calorimetry of HMT starches showed a broadened gelatinization temperature range and a shift in endothermal transition toward higher temperatures. After HMT, relative crystallinity decreased with increasing moisture level and X-ray diffraction patterns changed from B-type to a combination of B- and A-types. Hollow regions were found in the centres of HMT waxy potato starches. HMT intensity significantly influenced SDS level. This study showed that HMT-induced structural changes in waxy potato starch significantly affected its digestibility and the blood glucose levels of mice who consumed it.     

Effect of gelatinisation on slowly digestible starch and resistant starch of heat-moisture treated and chemically modified canna starches

The effects of gelatinisation on slowly digestible (SDS) and resistant starch (RS) of native and modified canna starches were investigated. Starch slurries (10% w/w) were gelatinised at 100 °C for 5, 10, 20 and 40 min using a rapid visco analyzer (RVA). Significant change in the degree of gelatinisation (DG) values of all starch samples was observed during the initial 10 min of gelatinisation; after that the DG values increased gradually with gelatinisation time. The RS contents in all gelatinised starches decreased with increasing gelatinisation time, while the SDS values fluctuated. Chemical modification affected DG values as well as RS/SDS contents. The RS contents in 10% (w/w) acetylated, hydroxypropylated, octenyl succinylated and cross-linked canna starches gelatinised at 100 °C for 40 min were 26.6%, 32.0%, 45.3% and 19.8%, respectively, which were higher than that of the native starch (12.4%). Canna starch modified by crosslinking had the highest SDS content when gelatinised for 20-40 min. Modification of canna starch by heat-moisture treatment resulted in a lower content of RS for all treated samples. However, the Vt-HMT25 (canna starch containing moisture content of 25% during heat treatment) when gelatinised for 5-20 min contained a higher amount of SDS, compared to unmodified starch. The most effective modification method for RS and SDS formation was octenyl succinylation, where the sum of RS and SDS approached that of Novelose260.     

Resistant starch and thermal,morphological and textural properties of heat‐moisture treated rice starches with high‐, medium‐ and low‐amylose content

This study investigated the effects of heat‐moisture treatment (HMT) on the resistant starch content and thermal, morphological, and textural properties of rice starches with high‐, medium‐ and low‐amylose content. The starches were adjusted to 15, 20 and 25% moisture levels and heated at 110°C for 1 h. The HMT increased the resistant starch content in all of the rice starches. HMT increased the onset temperature and the gelatinisation temperature range (T_finish–T_onset) and decreased the enthalpy of gelatinisation of rice starches with different amylose contents. This reduction increased with the increase in the moisture content of HMT. The morphology of rice starch granules was altered with the HMT; the granules presented more agglomerated surface. The HMT affected the textural parameters of rice starches; the high‐ and low‐amylose rice starches subjected to 15 and 20% HMT possessed higher gel hardness.     

Influence of heat–moisture treatment and annealing on functional properties of sorghum starch

Sorghum starch was annealed in excess water at 50 °C for 24 h. Starch was also modified under heat–moisture treatment at 110 °C after adjusting various moisture contents (20, 30 and 40%) for 8 h. Significant decrease in chain lengths of amylose fraction in HMT starches was observed. Heat moisture treated (HMT) and annealed (ANN) starches showed lower granule sizes, swelling power, peak and setback viscosity but higher retrogradation as compared to native starch. HMT starch with addition of 40% moisture showed a decrease in relative crystallinity. HMT and ANN starch gels were observed to be harder than native starch gel.     

颗粒态绿豆抗性淀粉的制备及性质研究

以绿豆淀粉为原料,采用湿热处理制备颗粒态抗性淀粉,并研究其颗粒形貌、直链淀粉含量、溶胀度、黏度及结晶性质等。试验表明:淀粉经过湿热处理后,抗性淀粉含量显著提高;湿热处理淀粉仍保持完整的颗粒外观,属于颗粒态抗性淀粉,部分淀粉颗粒表面出现了裂纹和凹坑,偏光十字强度有所减弱;湿热处理淀粉的直链淀粉含量明显增加,而溶解度、膨胀度和峰值黏度下降,淀粉糊化变得困难;X-射线衍射图谱表明原淀粉和湿热处理淀粉都为"A"型结晶,且湿热处理淀粉在15.2°、17.4°、22.9°左右的衍射峰强度有所加强。     

Effect of Heat‐Moisture Treatment on Structural and Thermal Properties of Rice Starches Differing in Amylose Content

Starches from glutinous rice (1.4% amylose), Jasmine rice (15.0% amylose) and Chiang rice (20.2% amylose) were exposed to heat‐moisture treatment (HMT) at 100 °C for 16 h and at different moisture levels (18, 21, 24 and 27%). The effect of heat‐moisture treatment on structural and thermal properties of these three rice starches was investigated. The HMT did not change the size, shape and surface characteristics of rice starch granules. The A‐type crystalline pattern of rice starches remained unchanged after HMT. The relative crystallinity (RC) and the ratio of short‐range molecular order to amorphous (RSA) of heat‐moisture treated glutinous and Jasmine rice starches decreased with increasing moisture level of the treatments. In contrast, the RC of the treated Chiang rice starch remained practically unchanged. A peak of crystalline V‐amylose‐lipid complexes was clearly presented in all treated Chiang rice starches. The peak became progressively stronger with increasing moisture level of the treatment. Differential scanning calorimetry (DSC) of all treated rice starches showed a shift of the gelatinization temperature to higher values. Increasing moisture level of the treatments increased the onset gelatinization temperature (T_o) but decreased the gelatinization enthalpy (ΔH) of rice starches. A broad gelatinization temperature range (T_c‐T_o) with a biphasic endotherm was found for all treated Chiang rice starches and Jasmine rice starch after HMT₂₇ (HMT at 27% moisture level). Additionally the (T_c‐T_o) of treated Chiang rice starches increased linearly with increasing moisture level of the treatments.     

Effect of heat-moisture treatment on rice starch of varying amylose content

The effect of heat-moisture treatment (HMT) on the properties of rice starches with high-, medium- and low-amylose content was investigated. The starches were adjusted to 15%, 20% and 25% moisture levels, and heated at 110 °C for 1 h. The swelling power, solubility, pasting properties, morphology, enzymatic susceptibility and X-ray crystallinity of the starches were evaluated. HMT reduced the swelling power and solubility of the starches. The strongest effect of HMT occurred on the high-amylose starch; the pasting temperature was increased and the peak viscosity, breakdown, final viscosity and the setback were reduced. HMT increased the starch’s susceptibility to α-amylase and promoted a reduction in the starch relative crystallinity.     

Hydrothermal treatments of rice starch for improvement of rice noodle quality

Two types of hydrothermal treated rice starches were prepared by annealing and heat-moisture treatment (HMT). Annealing of starch slurry was conducted at 55 °C for 24 h and HMT was applied in starch with 20 g/100 g moisture at 110 °C for 1.5 h, based on the optimization of the treatment conditions. The apparent changes on gelatinization, swelling, RVA paste viscosities and gel hardness of starch were observed. The study on 50% substitution of rice flour with untreated (UR), annealed (AR) or heat-moisture treated (HR) rice starches proved that the cooking and texture quality of rice noodle was substantially affected by the treatments. The composite noodles of flour and hydrothermal treated rice starches exhibited quality parameters which were closer to those of commercial noodles. The results revealed the possibility of utilizing these starches with low quality rice flour so as to produce noodles of acceptable quality. The study also inferred that characterization of RVA paste viscosities and gel texture of flour could become a practical method for predicting the quality of the derived noodle.     

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.     

Development of oxidised and heat-moisture treated potato starch film

This study investigated the effects of sodium hypochlorite oxidation and a heat-moisture treatment of potato starch on the physicochemical, pasting and textural properties of potato starches in addition to the water vapour permeability (WVP) and mechanical properties of potato starch films produced from these starches. The carbonyl contents, carboxyl contents, swelling power, solubility, pasting properties and gel texture of the native, oxidised and heat-moisture treated (HMT) starches were evaluated. The films made of native, oxidised and HMT starches were characterised by thickness, water solubility, colour, opacity, mechanical properties and WVP. The oxidised and HMT starches had lower viscosity and swelling power compared to the native starch. The films produced from oxidised potato starch had decreased solubility, elongation and WVP values in addition to increased tensile strength compared to the native starch films. The HMT starch increased the tensile strength and WVP of the starch films compared to the native starch.     

Pasting,Thermal, Hydration,and Functional Properties of Annealed and Heat-Moisture Treated Starch of Sword Bean (Canavalia gladiata)

The effects of annealing (ANN) and heat-moisture treatments (HMT) on the physicochemical and functional properties of Sword bean starches were investigated. The pasting properties differ significantly among the starches, with peak viscosity ranging from 399.17 RVU to 438.33 RVU; however, all the starches exhibited ‘Type C’ class with restricted swelling. The HMT starches had the highest gelatinization temperature, while change in enthalpy of gelatinization, ΔH_gel of the native starch, was higher (13.82 J/g) than that of the modified starches (1.39–6.74 J/g). The solubility and swelling power of all the starches increased as the temperature increased. The oil and water absorption capacity of the starches ranges between 3.24–3.91 g/g and 2.42–3.35 g/g, respectively. HMT (at 25 and 30% moisture level) changes the X-ray diffraction pattern of the starch from Type ‘B’ to Type ‘C’. The Scanning electron micrograph results revealed the starch granules with smooth ellipsoids and indentation in their centre, hydrothermal modification showed little effect on the morphology and size of the granules. Hydrothermal modification improved the physicochemical and functional properties of the starch without destroying the granule of the starch.     

Effect of deproteinization on degree of oxidation of ozonated starch

Effects of deproteinization on the degree of oxidation of ozonated starch (corn, sago, and tapioca) were investigated. Starch in dry powder form was exposed to ozone for 10 min at different ozone generation times (OGTs: 1, 3, 5, 10 min), and then native starches (NS) and deproteinized starches (DPS) were analyzed for protein content. Deproteinization caused a significant reduction in protein content for corn (∼21%) and sago (∼16%) starches relative to NS. Carbonyl and carboxyl contents increased significantly in all ozonated deproteinized starches (ODPS) with increasing OGT. Carbonyl and carboxyl contents of ODPS ranged from 0.03 to 0.13% and 0.14 to 0.28%, respectively. The carboxyl content for all ODPS was significantly higher than that of ozonated native starches (ONS). A Rapid Visco Analyser was used to analyze pasting properties of all starches. Deproteinization increased the pasting viscosities of corn and sago starches compared to their native forms. Generally, pasting viscosity of all ODPS decreased drastically as OGT increased. At the highest oxidation level (10 min OGT), all ODPS exhibited the lowest pasting viscosities compared to their ozonated native form, except for peak viscosity, breakdown viscosity, and setback viscosity for ozonated deproteinized corn starch. In conclusion, deproteinization as a pretreatment prior to starch ozonation successfully increased the degree of oxidation in the three types of starch studied. However, the extent of starch oxidation varied among the different starches, possibly due to differences in rates of degradation on amorphous and crystalline lamellae and in rates of oxidation of carbonyl and carboxyl groups.     

Effect of heat moisture treatment on resistant starch content among carbohydrate sources: a meta-analysis

Resistant starch (RS) can be generated through heat moisture treatment (HMT). The HMT was conducted by modifying starch using different ratio of moisture content, high temperature and heating time. A number of studies showed that the effects of HMT on RS contents in cereals, pulses, tubers and fruits were inconsistent. This study aimed to analyse the impact of HMT on RS level in various carbohydrate sources through a meta-analysis approach. Study selection was conducted with the PRISMA method. There were 21 relevant studies and 67 data used for meta-analysis. The database was analysed by using Hedges’ d. The results showed that there was a significant impact of HMT on RS level of cereals, especially wheat. The highest increase in RS levels for various carbohydrate sources in starch was influenced by the interaction of treatment between water content at 15 ≤ x < 25%, heating time at 0.25 < x ≤ 6 h and temperature at 120 ≤ x ≤ 130 °C.     

Mild hydrolysis of resistant starch from maize

To investigate structural changes of resistant starch (RS) caused by mild-acid treatment, native maize starch, retrograded (RS3), and cross-linked (RS4) resistant starches, prepared from maize starch, were hydrolyzed with 0.1 M HCl at 35 °C for 30 days. The hydrolysis rate of RS3 was shown to be the highest, at 44.1% after 30 days of the hydrolysis. The hydrolysis rapidly progressed upto 10 days but gradually changed after that. Native starch and RS4 showed less than 5% of hydrolysis during the period of hydrolysis. As for the RS level of the residue after the hydrolysis, RS4 did not show any significant change, but RS3 exhibited an increase of up to 25.9% after 30 days, which led to 88% increase in comparison with 13.8% at the initial stage. As a result of examining the molecular weight (MW) of RS3 by the SEC-MALLS-RI system, the non-hydrolyzed RS3 exhibited three peaks, having MW 53.4 × 10⁶, 7.4 × 10⁶, and 0.8 × 10⁶, respectively, but the MW of the molecules decreased to 4.9 × 10⁶ and 0.6 × 10⁶ after 7 days of hydrolysis. It was difficult to verify the MW of RS4 because this was not dispersed in 1 M NaOH. The crystallinity of native starches, RS3 and RS4, by X-ray diffractometry of the residue hydrolyzed with 0.1 M HCl was equal to that of the non-hydrolyzed starch. The peak intensity at 2θ = 17° of RS3 increased sharply after hydrolysis.     

Impacts of acid-methanol treatment and annealing on the enzymatic resistance of corn starches

Normal corn, Hylon V and Hylon VII starches were acid-methanol-treated at 25 °C for 1–30 days in methanol containing 0.36% HCl, and then annealing at 50 °C for 72 h in excess water. The rapid digestible starch (RDS), slow digestible starch (SDS) and resistant starch (RS) contents of starch before and after treatments were determined. The molecular structure, thermal properties, double helix content and relative crystallinity of starch were observed for elucidating the impacts of acid-methanol treatment and annealing, as well as the molecular structure, on the enzymatic resistance of starch. Results showed that the weight-average degree of polymerization of acid-methanol-treated corn starches ranged from 884 × 10³ to 404, 778 × 10³ to 299 and 337 × 10³ to 250 anhydrous glucose units for normal corn, Hylon V and Hylon VII starches, respectively. Annealing increased the RS content of starch, and the increment of RS increased with decreasing molecular size of starch. Furthermore, the change in RS content after treatments depended on the content and weight-average chain length of amylose fraction of starch. The RS content of starch after treatments increased from 19.2 to 56.2%, 69.9 to 86.1%, and 73.1 to 89.1% for normal corn, Hylon V and Hylon VII starches, respectively. The gelatinization peak temperature and double helix content of starch increased after acid-methanol treatment or annealing. Results demonstrate that the degradation of starch, causing by acid-methanol treatment, enhances the mobility and realignment of starch chains in molecules during treatments and further increases the enzymatic resistance of starch granules.     

Molecular structure,rheological and thermal characteristics of ozone-oxidized starch

The effects of oxidation by ozone gas on the molecular structure, rheological and thermal properties of starch (corn, sago and tapioca) were investigated. Starch, in dry powder form, was exposed to ozone for 10 min at different ozone generation times (OGTs). Average molecular weight decreased in oxidized corn and sago starches but increased in oxidized tapioca starch. All oxidized starches exhibited non-Newtonian shear-thinning behaviour. Starch viscosity decreased drastically with increasing OGT. Young’s modulus for all oxidized corn and sago starch gels stored for 1 and 7 days at 4 °C increased significantly compared to unmodified starch. No differences were noted in gelatinization temperatures and gelatinization enthalpies of all oxidized starches compared to unmodified starch. Retrogradation enthalpy increased markedly in corn starch after 1 min OGT. These results show that the extent of starch oxidation varies among starches of different botanical origins under similar ozone treatment conditions.     

Effect of single and dual hydrothermal treatments on the crystalline structure,thermal properties,and nutritional fractions of pea,lentil, and navy bean starches

Pea, lentil and navy bean starches were annealed at 50 °C (70% moisture) for 24 h and heat-moisture treated at 120 °C (30% moisture) for 24 h. These starches were also modified by a combination of annealing (ANN) and heat-moisture treatment (HMT). The impact of single and dual modifications (ANN–HMT and HMT–ANN) on the crystalline structure, thermal properties, and the amounts of rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) were investigated. Birefringence remained unchanged on ANN but decreased on HMT. Granular swelling and amylose leaching decreased on ANN and HMT. Relative crystallinity, gelatinization enthalpy, and short-range order on the granule surface increased on ANN but decreased on HMT. Gelatinization transition temperatures increased on ANN and HMT. Gelatinization temperature range decreased and increased on ANN and HMT, respectively. ANN and HMT increased SDS and decreased RS levels in all starches. However, RDS levels increased on ANN and HMT in pea and lentil starches but decreased in navy bean starch. In gelatinized starches, ANN and HMT decreased RDS level and increased SDS and RS levels. Changes to crystalline structure, thermal properties and amounts of RDS, SDS, and RS were modified further on ANN–HMT and HMT–ANN.     

An assessment of changes in thermal and physico-chemical parameters of jack bean (<Emphasis Type="Italic">Canavalia ensiformis</Emphasis>) starch following hydrothermal modifications

Starch isolated from jack bean was modified by heat moisture treatment (HMT) and annealing. Scanning electron micrograph indicates oval and round shape for the starch granules, with heterogeneous sizes. The range of the granule size for the starches was between 10 and 20 μm for the width and 14 and 32 μm for the length. The starches exhibited the characteristic “C” pattern for legume starches with increased starch crystallinity after modifications. Swelling power and solubility reduced following annealing and heat moisture treatment. The results also revealed that water absorption capacity increased following the heat moisture treatment but reduced after starch annealing. Both annealing and heat moisture treatment improved gelation capacity of the native starch. Gelatinization temperature increased after modifications. Both annealing and heat moisture treatments reduced starch retrogradation.     

Effect of Heat-Moisture Treatment and Acid Modification on Rheological, Textural, and Differential Scanning Calorimetry Characteristics of Sweetpotato Starch

Sweetpotato starches were characterized to understand the changes upon modification by acid and heat‐moisture treatment (HMT) in the rheological, differential scanning calorimetry (DSC), and textural characteristics of starch isolated from the sweetpotato variety PSP‐21 and to compare these findings with those of commercially available arrowroot starch. The native sweetpotato starch had a Type A pasting profile characterized by a high peak viscosity (PV) (741.5 rapid viscoanalyzer unit [rvu]), with a high breakdown (378.8 rvu) and low cold paste viscosity (CPV) (417.6 rvu). After HMT, there was a marked decrease in the PV (639.1), a very slight breakdown (113.5 rvu) and an increase in CPV (759.5 rvu), more like a Type C pasting profile. However, acid modification did not notably change the pasting profile of native sweetpotato starch. The DSC characteristics were also affected significantly after modifications. The gelatinization temperature parameter to onset (T_o) decreased significantly after HMT and acid modification. The gelatinization enthalpy decreased during HMT from 15.98 to 14.42 J/g. The gel strength of acid‐modified starch was the highest compared with that of HMT and native sweetpotato and arrowroot starches.