Understanding the multi-scale structure and digestibility of different waxy maize starches

Fractionation on debranched waxy maize starch by gradient ethanol combined with annealing to improve in vitro digestion resistance and hydrothermal stability of type 3 resistant starch

Retrograded resistant starch (RS3), as a prebiotic, has attracted great attention owing to a good stability and an edible feature. This study aims to demonstrate how molecular weights, structural properties, in vitro digestibility and hydrothermal behaviors of RS3 are influenced by gradient ethanol fractionation assisted with annealing. Waxy maize dextrin (WMD) was sequentially precipitated by different volume ratios of dextrin solution to absolute ethanol in an order of 0.5:1, 1:1, and 1.5:1. RS3 prepared from WMD through tertiary precipitation (RWMD 1.5) exhibited higher resistance to digestibility and hydrothermal stability. This was attributed to the high production of slowly digestible starch (SDS, 63.1 %) and resistant starch (RS, 32.1 %), together with the highest peak temperature (101.3 °C) and gelatinization enthalpy (16.2 J/g). Moreover, RWMD 1.5 was largely formed by uniform and short WMD (weight-average molecular weight, 2.990 kDa), which thus caused the formation of homogeneous A-type crystals with ordered structures.

A novel starch from Trichosanthes kirilowii roots: A comparison of its composition, structure and physicochemical properties with conventional root starch

This study investigated the properties of a novel medicinal starch isolated from the roots of Trichosanthes kirilowii (TKRS). The multiscale structural and physicochemical properties of TKRS were characterized and compared with two common starches, sweet potato starch (SPS) and kudzu starch (KS), to elucidate the influence of structural characteristics on the physicochemical properties of these root starches. TKRS granules exhibited elliptical and irregular polygonal shapes, with the largest median particle size (14.48 μm). TKRS had a lower amylose content (15.03 %) and a lower molecular weight (8.40 × 107 g/mol). XRD analysis confirmed a C-type crystallinity pattern, with a higher crystallinity degree (21.51 %) and a high degree of short-range ordered structure. Further analysis of the chain length distribution revealed that TKRS contained a larger proportion of long-chain amylopectin. Compared to SPS and KS, TKRS showed a lower gelatinization temperature (72.65 °C) but a higher peak viscosity (7351 cP). Additionally, despite its relatively lower water retention capacity, TKRS exhibited higher storage modulus and loss modulus than conventional tuber starches. In vitro digestibility analysis indicated that TKRS had a lower rapidly digestible starch content and a higher resistant starch content, highlighting its potential for processing into healthy starch-based food products.

Structure changes of starch complexed with green tea catechin or lemon peel caffeic acid under thermomechanical-assist low moisture and their prebiotics during in vitro digestion and fermentation

This paper highlighted the structural changes of rice starch complexed with green tea catechin and lemon peel caffeic acid under thermomechanical-assist low moisture, and their prebiotics during in vitro digestibility and fermentation were further explained. Extruded starch with caffeic acid, characterized by enhanced short-range order, a distinct fractal structure, and a V-amylose helical arrangement, exhibited slower glucose release due to V-type inclusion crystalline structures and strong hydrogen bondings. Additionally, extruded starch with catechin or caffeic acid changed the composition of gut microbiota by increasing the proliferation of good bacteria and reducing pathogenic microorganisms, which led to a greater synthesis of short-chain fatty acids. According to a PICRUSt2 analysis, the extruded starch with caffeic acid may trigger metabolic alterations via altering the gut microbiota and increasing bile acid metabolism. Thus, extruded starch with caffeic acid demonstrates significant potential as a prebiotic for developing nutritionally tailored starch-based foods.

Effect of Canna edulis starch addition on the properties of flour, rheology of dough and quality of semi-dry noodles

BACKGROUND

Canna edulis is a high-quality resistant starch raw material, especially for making flour products. This study aimed to investigate the effect of Canna edulis starch (CES) on the properties of flour, rheology of dough and quality of semi-dry noodles. The CES replaced part of the wheat flour in the semi-dry noodle formula. One control formula containing wheat flour only, and five formulations based on wheat flour containing 8CES, 16CES, 24CES, 32CES and 40CES were prepared.

RESULTS

The findings revealed that with the increase of CES, the peak viscosity and retrogradation value of the flour increased, and the melting enthalpy decreased. CES caused some bound water to migrate to a semi-bound water state, improving the rheological properties of the dough and enhancing the texture characteristics of the noodles. When the added amount of CES was 24%, the cooking loss rate was 1.687%, and the highest sensory score was 86 points. Simulation of starch in vitro digestion revealed that the hydrolysis rate of starch first increased and then decreased with the increase of CES addition, with the highest proportion of resistant starch content ranging from 44.27% to 79.66%. Compared with the control group, the expected glycemic index decreased after adding CES.

CONCLUSION

These results assist in realization of comprehensive utilization of Canna edulis resources for the production of noodles with desirable qualities. © 2025 Society of Chemical Industry.

Understanding the role of Radix Paeoniae Alba polysaccharide for corn starch gel amelioration: Physicochemical, structural, and digestive properties

To ameliorate the limitations of corn starch (CS) processing, Radix Paeoniae Alba polysaccharide (RPAP) was used to modulate the physicochemical and digestive properties of CS. The main purpose of this paper is to investigate the effects of RPAP on the pasting, rheological, thermal, structural, and digestive properties of CS. The results show that the addition of RPAP could increase the peak viscosity and final viscosity of CS gel, and RPAP could increase the apparent viscosity, storage modulus, loss modulus, hardness, and strength of CS gel, implying that RPAP can effectively improve the pasting and viscoelasticity properties of CS. Moreover, RPAP could be bound to CS through non-covalent interaction, and RPAP could improve the relative crystallinity and thermal stability, whereas decreased the spin relaxation time (T2) of CS from 312.16 to 203.25 ms. The microstructure of CS-RPAP gels showed a honeycomb-like porous structure, and RPAP could increase the pore size and thickness of CS-RPAP gels. Furthermore, RPAP could inhibit the digestibility of CS, while increased the resistant starch (RS) content. The findings can provide important references for expanding the application of starch-based products in various fields including food industry, pharmaceuticals, textiles, papermaking, and biodegradable materials.

Mechanism of multiscale structural reassembly controlled by molecular chains during amylase digestion of wheat starch

The digestive characteristics of wheat starch (WS) are closely related to its structure. However, the mechanisms underlying the multiscale structural evolution and reassembly controlled by molecular chains during digestion are poorly understood. To address this issue, amylopectin of wheat starch (APWS) and amylose of wheat starch (AMWS) were separated and digested in vitro. After digestion, chains in WS with a degree of polymerization (DP) < 12 or DP > 37 were degraded, the double-helix content decreased from 58.65 % to 48.77 %, and many particles were degraded. For APWS, the DP > 36 chains increased, the B-type crystallinity increased to 9.55 %, and the particles were transformed into new aggregated structures. For AMWS, the number of 18 < DP < 270 chains was increased, the double-helix content increased from 19.78 % to 37.92 %, the B-type crystallinity increased from 6.65 % to 19.40 %, and a dense granular structure was formed. Overall, our study confirmed that WS, APWS, and AMWS had distinct multiscale structural reassembly mechanisms during in vitro digestion. The DP > 36 chains in APWS and 18 < DP < 270 chains in AMWS were the primary contributors to the formation of enzyme-resistant multiscale structures. This study can serve as a theoretical basis for designing the WS multiscale structure using molecular chains to improve its nutritional value.

Recent Advances in Physical Processing Techniques to Enhance the Resistant Starch Content in Foods: A Review

The physical modification of starch to produce resistant starch (RS) is a viable strategy for the glycemic index (GI) lowering of foods and functionality improvement in starchy food products. RS cannot be digested in the small intestine but can be fermented in the colon to produce short-chain fatty acids rather than being broken down by human digestive enzymes into glucose. This provides major health advantages, like better blood sugar regulation, weight control, and a lower chance of chronic illnesses. This article provides a concise review of the recent developments in physical starch modification techniques, including annealing, extrusion, high-pressure processing, radiation, and heat-moisture treatment. Specifically, the focus of this paper is on the alteration of the crystalline structure of starch caused by the heat-moisture treatment and annealing and its impact on the resistance of starch to enzymatic hydrolysis, as well as the granular structure and molecular arrangement of starch caused by extrusion and high-pressure processing, and the depolymerization and crosslinking that results from radiation. The impacts of these alterations on starch's textural qualities, stability, and shelf life are also examined. This review demonstrates how physically modified resistant starch can be used as a flexible food ingredient with both functional and health benefits. These methods are economically and ecologically sustainable since they successfully raise the RS content and improve its functional characteristics without the need for chemical reagents. The thorough analysis of these methods and how they affect the structural characteristics and health advantages of RS emphasizes the material's potential as an essential component in the creation of functional foods that satisfy contemporary dietary and health requirements.

Structure and functional characteristics of starch from different hulled oats cultivated in China

This work aimed to evaluate the structure and functional characteristics of starch from ten hulled oat cultivars grown in different locations in China. The protein, phosphorus, amylose, and starch contents were 0.2-0.4 %, 475.7-691.8 ppm, 16.2-23.0 %, and 93.6-96.7 %, respectively. All the starches showed irregular polygonal shapes and A-type crystallization with molecular weights ranging from 7.2 × 107 to 4.5 × 108 g/mol. The amounts of amylopectin A (DP 6-12), B1 (DP 13-24), B2 (DP 25-36), and B3 (DP > 36) chains were in the ranges of 10.3-16.0 %, 54.5-64.8 %, 16.5-21.1 %, and 4.9-13.1 %, respectively. The starches differed significantly in gelatinization temperatures, pasting viscosity, solubility, swelling power, rheological properties, and digestion parameters. The results revealed that the larger particle size could increase the peak viscosity of the starch paste. The presence of phosphorus increased the gelatinization temperature and enhanced the resistant starch content. The starch granules with higher crystallinity contained a higher proportion of phosphate, which increased final viscosity and setback viscosity but decreased rapidly digestible starch. Overall, oat starch with a high phosphorus content could be used to prepare low-glycemic-index food for diabetes patients.

Effects of exogenous salicylic acid on starch physicochemical properties and in vitro digestion under heat stress during the grain-filling stage in waxy maize

Waxy maize starch serves as a pivotal component in global food processing and industrial applications, while high temperature (HT) during the grain-filling stage seriously affects its quality. Salicylic acid (SA) has been recognized for its role in enhancing plant heat resistance. Nonetheless, its regulatory effect on the quality of waxy maize starch under HT conditions remains unclear. In this study, two waxy maize varieties, JKN2000 (heat-tolerant) and SYN5 (heat-sensitive) were treated with SA after pollination and then subjected to HT during the grain-filling stage to explore the effect of SA on grain yield and starch quality. The results indicate that exogenous SA under HT treatment led to an increase in kernel weight and starch content in both varieties. Moreover, SA reduced the HT-induced holes on the surfaces of starch granules, enlarged the starch granule size, elevated the amylopectin branching degree, and reduced amylopectin average chain length. Consequently, improvements of pasting viscosity and the decrease of retrogradation percentage of starch were observed with SA under HT. Exogenous SA reduced HT-induced rapidly digestible starch content in SYN5, but had no significant effect on that in JKN2000. In summary, SA pretreatment effectively alleviated the detrimental effects of HT on starch pasting and thermal properties of waxy maize.

Improvement of in vitro digestibility and thermostability of debranched waxy maize starch by sequential ethanol fractionation

This study aimed to improve the in vitro digestibility and thermostability of debranched waxy maize starch (DWMS) by sequential fractionation. Waxy maize starch was debranched by pullulanase, followed by sequential precipitation through controlling the ratio of starch supernatants to ethanol at 1:0.5, 1:1, and 1:1.5 (v/v). Subsequently the structural, thermal, in vitro digestive properties of DWMS were investigated. In vitro digestion results showed that the secondary ethanol fractionation of 1:1 on the basis of the initial fractionation (1:0.5) induced a significant higher amount of slowly digestive starch (SDS, 30.0 %) and resistant starch (RS, 58.6 %) amongst all three fractions, along with the highest peak temperature (Tp, 106.4 °C) and the highest decomposition value (Td, 310.0 °C) in calorimetric (DSC) and thermogravimetry (TGA) measurements. Chain length distribution, surface morphology, and laser confocal micro-Raman spectroscopy (LCM-Raman) analyses revealed that medium (degree of polymerization, DP 13- 36) and long chains (DP ≥37) respectively constituting 72.0 % and 10.2 % of DWMS resulted in the formation of spheroidal crystallites with higher homogeneity and more ordered short-range structures. Overall, this work confirmed that ethanol fractionation is an efficient method for improving the in vitro digestibility and heat stability of waxy maize starch.

Comparison of structures and properties of gels formed by corn starch with fresh or dried Mesona chinensis polysaccharide

Starch is a major dietary carbohydrate, but its digestion properties need to be improved. Mesona chinensis polysaccharides (MCPs) had a unique function in improving the flocculation performance of starch. This study investigated the effects of adding Mesona chinensis polysaccharide extracted from wet fresh and dry plants with one-year storage, namely WMCP and DMCP, on the physicochemical properties and digestion kinetics of corn starch(CS). The composition analysis showed both WMCP and DMCP were an acidic heteropolysaccharide rich in galacturonic acid and galactose, whereas showed different average main fraction molecular weights (Mw) of 47.36 kDa and 42.98 kDa, respectively. In addition, WMCP showed higher yield, purity and better physicochemical properties to CS than DWCP. Thermal analysis showed WMCP decreased more gelatinization temperatures and enthalpy of CS, and increased more freeze-thaw stability, water holding capacity, and textural parameters of CS gels than DMCP. Structural analysis revealed WMCP induced more changes in crystallinity, short-range order, and microstructure of CS, which inhibited retrogradation than DMCP. In vitro digestion assays demonstrated WMCP addition significantly increased higher resistant starch content by altering starch-starch and starch-MCP interactions than DWCP. Overall, MCPs addition beneficially modulated CS properties and digestion kinetics, providing a novel way to improve starch functionalities. Moreover, WMCP had more advantages to be chosen to form hydrocolloid with CS than DMCP.

Cross-linked modifications of starches from colored highland barley and their characterizations, digestibility, and lipolysis inhibitory abilities in vitro

To promote the stability and functionality of native starch from colored highland barley (CHBS), the cross-linked modifications with sodium trimetaphosphate (STMP)/sodium tripolyphosphate (STPP) and citric acid were conducted to prepare CHB resistant starches (CHRSs), whose physicochemical characteristics, digestibility, and lipolysis inhibitory potential were also assessed. Results showed that the resistant starch amounts in CHBS were significantly increased after cross-linking and differed slightly among CHRSs. Citric acid modification of CHBS resulted in significantly higher amylose amounts, solubilities, swelling powers, and water-binding capacities than those under STMP/STPP modification within the cultivars (p < 0.05), with their crystalline patterns of A-type (white and blue) and CB-type (black). STMP/STPP modified CHBS exhibited higher degrees of crystalline regions with B-type crystalline patterns. Due to the differences in structural properties and structure-based morphology, STMP/STPP cross-linked CHBS showed lower digestibility and citric acid cross-linked CHBS exhibited higher lipolysis inhibitory activities. Besides, the cross-linked modifications demonstrated more enhancements in functionalities of starches from white and blue cultivars than black cultivar.

Effects of biochar coupled with chemical and organic fertilizer application on physicochemical properties and in vitro digestibility of common buckwheat (Fagopyrum esculentum Moench) starch

Common buckwheat starch, a functional ingredient, has wide food and non-food applications. Excessive chemical fertilizer application during grain cultivation decreases quality. This study examined the effects of different combinations of chemical fertilizer, organic fertilizer, and biochar treatment on the physicochemical properties and in vitro digestibility of starch. The amendment of both organic fertilizer and biochar was observed to have a greater impact on the physicochemical properties and in vitro digestibility of common buckwheat starch in comparison to organic fertilizer amendment solely. The combined application of biochar, chemical, and organic nitrogen in an 80:10:10 ratio significantly increased the amylose content, light transmittance, solubility, resistant starch content, and swelling power of the starch. Simultaneously, the application reduced the proportion of amylopectin short chains. Additionally, this combination decreased the size of starch granules, weight-average molecular weight, polydispersity index, relative crystallinity, pasting temperature, and gelatinization enthalpy of the starch compared to the utilization of chemical fertilizer alone. The correlation between physicochemical properties and in vitro digestibility was analyzed. Four principal components were obtained, which accounted for 81.18 % of the total variance. These findings indicated that the combined application of chemical fertilizer, organic fertilizer, and biochar would improve common buckwheat grain quality.

Fabrication of octenyl succinic anhydride starch grafted with folic acid and its loading potential for doxorubicin hydrochloride

In this study, octenyl succinic anhydride (OSA) starch with different folic acid (FA) grafting time was prepared and the degree of FA substitution at different grafting time was determined. The results of XPS quantitatively reflected the surface elemental composition of OSA starch grafted with FA. FTIR spectra further confirmed the successful introduction of FA on OSA starch granules. SEM images showed that the surface roughness of OSA starch granules was more obvious with higher FA grafting time. The particle size, zeta potential, and swelling properties were determined to study the effect of FA on the structure of OSA starch. TGA indicated that FA effectively enhanced the thermal stability of OSA starch at high temperature. The crystalline form of the OSA starch gradually transformed from A type to a hybrid A and V-type with the progress of FA grafting reaction. In addition, the anti-digestive properties of OSA starch were enhanced after grafting FA. Using doxorubicin hydrochloride (DOX) as the model drug, the loading efficiency of OSA starch grafted with FA for DOX reached 87.71 %. These results provide novel insights into OSA starch grafted with FA as potential strategy for loading DOX.

Study on structural characteristics and physicochemical properties of starches extracted from three varieties of kudzu root (Pueraria lobata starch)

Kudzu root (Pueraria lobata) is well known for its traditional use as a medicinal food homologous plant in China. Three varieties of kudzu roots, such as Gange-1, Gange-2, and Gange-6, are commonly used. Nowadays, kudzu starch (KS) is commercially available as satiating foods or product ingredients. Differentiation and selection of the variety are important components of quality control for KS-based products. Thus, the present work was aimed at comparing the physicochemical properties, such as thermodynamic properties, pasting properties, solubility, swelling, as well as the structural characteristics of the starches extracted from the three varieties of kudzu roots. The results show that KS-6 has a higher content of functional ingredients thus can be used as an ideal functional starch. However, KS-6 has a higher amylopectin:amylose ratio of 4.65, resulting in a better solubility, higher transition temperature, and higher gelatinization enthalpy. KS-2 showed lower transition temperature and gelatinization enthalpy, as well as higher peak viscosity, through viscosity, and final viscosity. KS-1 could result in a soft texture after pasting. The appropriate variety of KS should be differentiated and selected according to application scenarios. This study provided valuable insights into the potential use of different KS in the food and nonfood industries. PRACTICAL APPLICATION: 1. KS-1 was found to be suitable for use as a food supplement. 2. KS-6 has the highest nutritional value. 3. They can be used as a substitute for other similar starches.

Effects of non-covalent binding of lignans with rice starch driven by high-pressure homogenization on the starch structure and in vitro nutritional characteristics

As a type of phytoestrogen, lignans have attracted attention in recent years for their nutritional functions. To investigate the effects of lignans on the structural and nutritional functions of starch, honokiol (HK) and arctiin (AC) were complexed with rice starch respectively under high-pressure homogenization (UHPH) (UHPHRS/HK and UHPHRS/AC). The results showed that both HK and AC could form inclusive complexes with rice starch via non-covalent bonding (hydrophobic interaction and hydrogen bonds), and these complexes could further form V-type crystals and aggregates, which reduced the starch digestibility as well as endowing them with the ability to retard glucose release and bind sodium cholate. Interestingly, due to its smaller molecular size, HK could induce starch to form a more compact structure than AC, leading to better nutritional functions. When the addition of HK/AC reached 8%, the resistant starch content could reach 26% and 19.8%, respectively. Meanwhile, the glucose dialysis retardation index could increase to 17.2% and 14.8%, respectively, and the sodium cholate-binding capacity could increase to 33.1 mg g^-1 and 21.8 mg g^-1, respectively. These results demonstrated that UHPH with lignans' molecular interaction could be beneficial for controlling the nutritional functions of starch products with the desired digestibility.

Multi-scale structures and physicochemical properties of waxy starches from different botanical origins

The multi-scale structures and physicochemical relationships of three different types of waxy starches (maize, tapioca, and potato) were investigated. The maize and tapioca starches exhibited A-type crystalline polymorph compared to potato starch (B-type). The WMS showed higher amorphous content (5.56 %) than other waxy starches. The WTS exhibited a low tendency of retrogradation with its high f_a (DP 6-12) and low f_b3 (DP ≥ 37) proportion of chains. Double helix content of WPS was observed highest with a high pasting viscosity (952.3 BU). Low f_a (DP 6-12) and high f_b3 (DP ≥ 37) chain proportions of the WPS retrograded easily. The compactness of the semi-crystalline aggregation structure influenced the retrogradation properties of waxy starches with a positive correlation. Furthermore, the peak viscosity of pastes was correlated with the proportion of f_b3 (DP ≥ 37) chains, mass fractal dimension, and double helix content. The results provide guidance to design the application of waxy starches in the production of clean-labels.

Increasing agar content improves the sol-gel and mechanical features of starch/agar binary system

Starch/agar systems are highly potential for versatile applications such as packaging and biomedical materials. Here, how combined factors affect the features of a starch/agar binary system were explored. An increase of starch amylose/amylopectin ratio from 0/100 to 50/50 increased the sol-gel transition temperature and gel hardness of the aqueous starch/agar mixture. An increased agar content (mainly from 30% to 70%) allowed increases in both the tensile strength (reaching 50-60 MPa) and elongation at break of the starch/agar binary films. This phenomenon should be related to the strengthened crystalline structure and the weakened hydrogen bonding between starch chains (reflected by infrared spectroscopy). Furthermore, a higher relative humidity (from 30% to 70%) allowed enhanced chain interactions and probably nanoscale molecular order but weakened the crystalline structure, leading to reduced tensile strength and increased elongation at break. This work could facilitate the design of starch/agar binary systems with improved sol-gel and mechanical performance.

Development changes in multi-scale structure and functional properties of waxy corn starch at different stages of kernel growth

Waxy corn starch is widely used in food and papermaking industries due to its unique properties. In this work, the structural and functional properties of starch isolated from waxy corn at different stages of kernel growth were investigated and their relationships were clarified. The results showed that with kernel growth, the surface of starch granules became smooth gradually, and the inner growth rings and the porous structure grew and became clear. Meanwhile, the weight-average molecular mass (M_w), root mean square radius (R_g), and average particle size increased while the amylose content decreased, which should account for the decreased pasting temperature (from 71.37 to 67.44 °C) and increased peak viscosity (1574.2 to 1883.1 cp) and breakdown value observed. Besides, the contents of slowly digestible starch (SDS) and resistant starch (RS) in waxy corn starch decreased significantly (from 44.01% to 40.88% and from 16.73% to 9.80%, respectively, p < 0.05) due to decreases in the double helix content, crystallinity, and structural order, and increases in the semi-crystalline lamellae thickness and the amorphous content. This research provides basic data for the rational utilization of waxy corn starch at different stages of kernel growth.

Analysis of Sour Porridge Microbiota and Improvement of Cooking Quality via Pure Culture Fermentation Using Lacticaseibacillus paracasei Strain SZ02

The microbial composition of sour porridge at different fermentation times was analyzed through high-throughput sequencing, and a pure culture fermentation process was established to optimize production process and improve the edible quality of the porridge. In natural fermentation, Firmicutes and Proteobacteria were abundant throughout the process. Specifically, Aeromonas, Acinetobacter, and Klebsiella were dominant on fermentation days 1–5 (groups NF-1, NF-3, and NF-5), while Lactobacillus and Acetobacter gradually became the dominant bacteria on fermentation day 7 (group NF-7). Further, we isolated one strain of acid-producing bacteria from sour porridge, identified as Lacticaseibacillus paracasei by 16SrRNA sequencing and annotated as strain SZ02. Pure culture fermentation using this strain significantly increased the relative starch and amylose contents of the porridge, while decreasing the lipid, protein, and ash contents (P < 0.05). These findings suggest that sour porridge produced using strain SZ02 has superior edible qualities and this strategy may be exploited for its industrial production.

In vitro digestibility and structural control of rice starch-unsaturated fatty acid complexes by high-pressure homogenization

This study emphasized on structural alteration of rice starch-unsaturated fatty acid complexes by adding trans-2-dodecaenoic acid (t12), trans-oleic acid (t18), cis-oleic acid (c18) and linoleic acid (loa) with different concentration under high-pressure homogenization treatment, and further illustrated the underlying mechanism of modulating digestibility. Results showed that the complex primarily presented as V6 or type IIa polymorph; complex index, content of ordered structure and thermal stability appeared to be positively correlated to the concentration of unsaturated fatty acids. t12 was too mobile to form single helix, leading to the formation of loose matrix; t18 fitted better within the cavity of starch than c18, and formed structural domain with higher compactness and thermal stability; Rloa had lower complex index but higher degree of short-range order, and tended to form alternating amorphous and crystalline structure. The digestibility was higher in the order of Rloa, Rt18, Rc18 and Rt12.