Slowly Digestible Starch Content Research Articles

Changes in physicochemical, nutritional characteristics and ATR-FTIR molecular interactions of cereal grains during germination.

The cereal grains such as wheat, barley, sorghum, millets were evaluated before and after germination (24h, 48h and 72h) and compared for their proximate composition, antioxidant activity, total phenolic content, total flavonoid content, pasting properties, in vitro starch digestibility and FTIR spectroscopy. Germination inversely affected the protein, fat, and ash content of different cereal grains. The germinated flours have less water content and higher oil absorption capacities along with reduced starch content. The contents of rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) in the ungerminated cereal flours ranged from 20.7 to 32.1%, 26.9 to 38.0% and 6.2 to 17.6% respectively but after germination of 72h, the RDS content increased from 26.5 to 36.2% while SDS and RS content decreased from 26.1% (sorghum) to 16% (barley) and 14.7% (barley) to 4.6% (wheat) respectively. The drought-tolerant crops (sorghum, millets and barley) are potential sources of antioxidants and phenolic content and yielded lower hydrolysis index and estimated glycaemic index upon germination. The highest section of antiparallal β-sheet, α-helix and β-turns were found in wheat flour followed by sorghum flour and their proportion decreased with continuous germination. The continuous reduction of viscosity was evaluated with the progress in germination. Overall, germination is a way to get health-promoting compounds from less utilizing cereal such as millets, sorghum and barley and enhance their uses to nourish the huge population with the aim to fulfill their nutritional requirements.

Effects of fatty acids with various chain lengths and degrees of unsaturation on the structure, physicochemical properties and digestibility of maize starch-fatty acid complexes

In this study, we investigated the effects of chain length and degree of unsaturation of fatty acid (FA) on the structure, physicochemical properties, and in vitro digestibility of maize starch (MS)–FA complexes. Differential scanning calorimetry, X-ray diffraction, and Raman spectroscopy revealed that crystalline structure with V-type was formed between MS and FA. Nuclear magnetic resonance spectroscopy confirmed that the complexes with various FA structures displayed different V-type polymorphs. The thermal stability of the complexes with 14-carbon and 16-carbon FAs was better than that of other complexes. The complexes with 12-carbon (21.77%) and 14-carbon (26.31%) FAs displayed high resistant starch (RS) content, whereas those with 10-carbon FAs exhibited high slowly digestible starch (SDS) content (28.99%). Additionally, the FAs with a chain length of 10–14 carbons produced more ordered structures and showed stronger intermolecular interactions with MS than other FAs. For the 18-carbon FAs, the complexes with unsaturated FAs displayed higher RS and SDS content than those with saturated FAs. Moreover, the unsaturated FAs showed stronger intermolecular interactions with MS than the saturated FAs. These results indicated that FA structures significantly affected the structures of complexes, further affecting their physicochemical and digestive properties.

Inhibition of Starch Digestion by Dallic Acid and Alkyl Gallates

Abstract Objectives Retardation of starch digestion is an effective way of optimizing glycemic response. Certain bioactive food components inhibit starch digestion by binding with starch digestive enzymes or starch molecules in the digestive tract. Inclusion complexation between starch and guest compounds is a specific non-covalent binding mode and may contribute to a lower digestibility of starch. The aim of this study was to examine the inhibitory effects of alkyl gallates on in vitro starch digestion and the mechanism of inhibition. Methods Raw and cooked high amylose maize starch (HAMS) and potato starch (PS) were tested for in vitro enzymatic digestion. Gallic acid (GA) and alkyl gallates, including butyl (BG), octyl (OG), dodecyl (DG), hexadecyl (HG), and octadecyl (SG) gallates, were either added during digestion or processed to form inclusion complexes with starch prior to digestion. Starch digestibility profiles, represented by rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) contents, were determined. Results GA and alkyl gallates significantly increased (P < 0.05) RS content in raw starches. Cooked starches had significantly lower RS contents than raw starches. GA and BG increased RS content in cooked HAMS, while all compounds except for SG increased RS content in cooked PS. DG and HG caused a significant increase in SDS contents in cooked HAMS but not in raw starches and cooked PS. Significant increases in SDS and RS contents were seen in HAMS inclusion complexes with DG and HG, compared with uncomplexed starch. Conclusions The bioactive food components tested could all inhibit starch digestion either by inhibiting the enzymes or by forming starch inclusion complex. As alkyl chain length increased, their inhibition on enzymatic activity decreased, but their ability to bind starch increased. While cooking makes starch more digestible, adding certain bioactive food components could compensate for RS loss, suggesting a practical way of modulating glycemic response. Funding Sources USDA National Institute for Food and Agriculture.

Enzymatic digestion of amylose and high amylose maize starch inclusion complexes with alkyl gallates

The interactions between starch and phenolic compounds have a great impact on the physicochemical and nutritional properties of starch-containing foods. One particular form of the interaction is starch-guest inclusion complexation, which is a specific non-covalent interaction formed between starch and guest molecules. This study investigates complexation ability and enzymatic digestibility profiles of amylose and high amylose maize starch (HAMS) inclusion complexes with gallic acid (GA) and alkyl gallates of various chain lengths, including butyl (BG), octyl (OG), dodecyl (DG), hexadecyl (HG), and octadecyl (SG) gallates. The formation of inclusion complex was examined by complementary techniques including differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. The digestibility profiles, represented as rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) contents, were obtained through simulated in vitro enzymatic digestion assays. The results showed that while GA, BG, and OG were not capable of forming inclusion complex with either amylose or HAMS, gallates with longer alkyl chains were able to form more stable inclusion complexes. Precipitated amylose and HAMS samples without inclusion complex formation contained the lowest RDS and highest SDS + RS, probably due to starch retrogradation. Amylose and HAMS inclusion complexes with long alkyl chain, particularly HG and SG, also possessed the lowest RDS and highest SDS + RS, but higher SDS proportions than the non-complexed starch samples. It was suggested that the inclusion complexes, especially amylose-HG and SG, and HAMS-DG, HG, and SG, might have contributed to the increase in SDS content. The water insusceptibility and high thermal stability of these inclusion complexes helped retard the starch digestion. The resistant yet steady digestion behavior of the starch-gallate inclusion complexes has significant implications in modulating glycemic response, as well as enabling a slow and sustained release of bioactive guest compounds into the gastrointestinal tract.

Effect of immature wheat flour on nutritional and technological quality of sourdough bread

In this study, the effect of immature wheat flour (IWF) on the fermentation activity of lactic acid bacteria (LAB) and on the nutritional quality properties of bread were evaluated. IWF was added in the as the ratio of 10g/100g in sourdough fermentation medium, and the fermentation activity (total LAB, pH, titration acidity (TA), and total reducing sugar (TRS)) of LAB cultures was monitored. Additionally, some physical quality characteristics (specific volume, texture profile and colour value), estimated glycaemic index (eGI), rapidly digestible starch (RDS), slowly digestible starch (SDS), and the total dietary fibre content of sourdough bread were determined. According to the statistical test, it was revealed that the IWF addition stimulated LAB growth and increased their fermentation activity. The pH of the fermentation medium decreased from 6.57 to 3.50, and TA raised from 0.13% to 1.2% in 48 h. The highest TRS content was determined in IWF enriched sourdough samples, and as a result of this, the eGI of sourdough bread increased. Compared to the control sample, the SDS and total dietary fibre content were higher in IWF added sourdough bread, and a positive correlation was noted between these two components. IWF utilisation of sourdough bread formulation increased the hardness value by nearly 50%.

Effect of Different Heat Treatments on Physicochemical Properties and Structural and Digestibility of Water Caltrop Starch

AbstractWater caltrop has a high starch content and is a promising resource of starch in Asia. Starch can be divided into rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS). Here, the effects of physical modification by microwave treatments, heat–moisture treatments, and pressure–heat treatments on the physiochemical and structural properties and on the in vitro digestibility of water caltrop starch is studied. The results show that, compared with native starch (NS), the solubility and swelling power of modified starch samples decrease with prolonged microwave and heat–moisture treatment. The infrared absorbance ratio at 1047 cm−1/1022 cm−1 is decreased in starch samples modified by microwave treatment and pressure–heat treatment, the NS samples present a C‐type crystalline pattern which changes into an A‐type pattern upon microwave treatment. Water caltrop starch subjected to 50 s of microwave treatment has the highest amylose (48.78%), the highest crystallinity (42.95%), and the highest RS content (67.41%, uncooked and 48.91%, cooked). Water caltrop starch subjected to 3 h of heat–moisture treatment contains the highest SDS content (54.33%, uncooked and 60.11%, cooked).

Glycemic profile is improved by High Slowly Digestible Starch diet in type 2 diabetic patients

AbstractIntroductionConsidering the dramatically increasing incidence of type 2 diabetes (T2D), decreasing glycemic variability in T2D patients is a key challenge to limit the occurrence of diabetic complications. Diet appears as one potential lever that can be set up above medications. Particularly, the ingestion of foods with a high content in slowly digestible starch (SDS) demonstrated both lower postprandial glycemic and insulin responses in healthy and insulin resistant subjects. This study aimed at designing a full high-SDS diet by selecting high-SDS starchy food products and at studying its impact on glycemic response and variability in T2D.Materials and methodsThis pilot randomized controlled cross-over study included eight T2D patients (HbA1c = 7.0 ± 0.2%, BMI = 31.7 ± 2.1 kg/m2, treated by Metformin & Sitagliptin) who consumed twice, for one week a controlled diet containing starchy food products screened and selected to be either High (High-SDS) or Low (Low-SDS) in SDS, as determined by the SDS in-vitro method developed by Englyst et al. During each diet period, the glycemic profile was monitored for 6 days using a Continuous Glucose Monitoring System (CGMS). Multiple metrics related to variability and glycemic responses were calculated.Results222 SDS analyses were realized on commercial food products as consumed. 23 High-SDS and 20 Low-SDS food items with associated specific cooking instructions were selected to design two diets consistent with local T2D recommendations. The High-SDS diet demonstrated a significantly higher SDS content compared to the Low-SDS diet (61.6 vs 11.6 g/day; p < 0.0001), mainly driven by selected pasta, rice and high-SDS biscuits (75.6% of the consumed SDS content). The % of total daily energy intake (TDEI) for all macronutrients remained similar between diets (p > 0.05) and the carbohydrate content specifically represented 49 ± 1 % and 47 ± 2 % of the TDEI for High-SDS and Low-SDS diets, respectively. With the high-SDS diet, the Mean Amplitude of Glycemic Excursion, a key parameter of glycemic variability, was significantly decreased (79.6 for Low-SDS vs 61.6 mg/dL for High-SDS; p = 0.0067). The significant correlation between the meals SDS contents and various glycemic parameters such as postprandial iAUC, tAUC (up to 180 min) or peak value strengthen this finding (p < 0.05 for all).DiscussionIt was the first demonstration that a diet including selected starchy food items and cooking recommendations designed to favor products’ high SDS content beneficially impacts glycemic profile in T2D subjects. Carefully selecting starchy food may be a simple and valuable tool to improve glycemic control in T2D.

A high content of Slowly Digestible Starch decreases glycemic and insulinemic responses similarly in Asians and Caucasians

AbstractIntroductionGlucose intolerance and type 2 diabetes are increasing worldwide. Current scientific evidence tends to demonstrate that people with an Asian phenotype have a lower glucose tolerance compared to Caucasian phenotype. In addition, in Caucasian population, consumption of products with a high content of Slowly Digestible Starch (SDS) significantly decreases postprandial glycemic and insulinemic responses compared to products with a low-SDS content. The aim of this study was to evaluate the effect of consuming products with varying levels of SDS on postprandial glycemic and insulinemic responses, both in Asian and Caucasian populations.Materials and methodsFive products with varying starch digestibility profiles (determined by the SDS method developed by Englyst) and one glucose solution were tested. A randomized cross-over controlled study was set up in the University of Sydney to study the products’ Glycemic and Insulinemic Indexes (GI and II) and postprandial responses over 2 hours. 12 Caucasian and 12 Asian participants were recruited and consumed 50 g of available carbohydrates from each product (norm ISO-26642(2010)).ResultsAsian participants were 28.0 ± 2.6 yo with a body mass index (BMI) of 21.4 ± 0.3 kg/m2 and Caucasians were 26.0 ± 1.1 yo with a BMI of 22.4 ± 0.5 kg/m2 (no difference between groups). Among the products tested, 3 had a high-SDS content (26 to 28 g SDS / 100g) and 2 had a low-SDS content (0 to 2 g SDS / 100g). GI values for Asian participants ranged between 44 and 54 for high-SDS products (low GI) and were medium (64) or high (90) for low-SDS products. GI values for Caucasian participants ranged between 40 and 48 for high-SDS products (low GI) and between 60 and 79 for low-SDS products. In a statistical model including product effect, ethnicity effect, session effect, and the interaction term product*ethnicity, the product effect was the only significant parameter and products were split according to their SDS content. Furthermore, products with a high-SDS content decrease the glycemic peak value by about 1 mM, both in Asian and Caucasian participants. Consumption of high-SDS products also decreases the insulin demand by 29% and 32% in Asians and Caucasians respectively compared to low-SDS products.DiscussionOur study demonstrates that consumption of products with a high-SDS content similarly decreases the glycemic and insulinemic responses in both Asian and Caucasian participants. This decrease may be beneficial in the long term to prevent metabolic diseases.

Structural characteristics of low-digestible sweet potato starch prepared by heat-moisture treatment

The objectives of this study were to optimize the conditions for the preparation of sweet potato starch containing a high proportion of slowly digestible starch (SDS) by heat-moisture treatment (HMT), and to investigate the structural properties of SDS and resistant starch (RS) fractions isolated from this modified starch. Response surface methodology evaluation of considering temperature, time, and moisture content was conducted to determine the HMT condition for maximizing SDS yield. Maximum SDS content (50.9%) was obtained after 8.6 h at 113 °C with 22.8% moisture level. Scanning electron micrographs of RS fractions displayed growth ring structure and hollow regions. X-ray diffraction patterns of SDS + RS and RS fractions were not changed by HMT. Gelatinization enthalpy of the SDS + RS fraction was decreased more than that of the RS fraction. The results indicated that the SDS fraction consisted of less perfect crystallites and amorphous regions, whereas the RS fraction was composed mostly of crystalline regions.

The loosening effect of tea polyphenol on the structure of octenyl succinic anhydride modified waxy maize starch

Octenyl succinic anhydride modified waxy maize starch after heat-moisture treatment (HT-OSAS) is a heat-stable slowly digestible starch (SDS), but the mechanism is poorly understood. Tea polyphenols (TP), as a probe with hydrophobic moiety, were employed to study the structural basis for its slow digestion. The content of RS (8.91%) in the HT-OSAS was significantly increased by TP in a dose-dependent manner (19.06% at TP of 15%) while there is a slight decrease of SDS content (34.85–30.63%). However, after retrogradation for one week, TP significantly reduced the SDS content (29.79%–15.67%). Additionally, TP increased the hydrodynamic radius of HT-OSAS (60–102 nm), but reduced its emulsifying activity (−35%), gelatinization enthalpy (−45%), and viscosity (−66%), demonstrating an inhibitory effect of TP on the association of HT-OSAS molecules, and a compact physical structure of HT-OSAS formed through OSA-mediated hydrophobic interaction is likely the basis to its slow digestion property. Novel strategies to densify the physical structure of starch could improve the nutritional quality of starch with a slow digestion property.

Effect of chitosan on the digestibility and molecular structural properties of lotus seed starch

The effect of chitosan (CS) on the in vitro digestibility and molecular structural properties of lotus seed starch (LS), and the correlation matrix was studied. The addition of CS could delay the hydrolysis of LS due to a increased level of slowly digestible starch (SDS). LS-CS blends exhibited lower pasting viscosity, greater amylose content and higher ordered structure than LS alone. A significant correlation was found between the digestibility and molecular structural properties of LS-CS blends. Rapidly digestible starch content was positively correlated with viscosity and full width at half-maximum height (FWHH) at 480 cm−1; whereas, SDS content was negatively correlated with setback and FWHH. Moreover, CS concentration was positively related to absorbances at 1047 and 1035 cm−1and amylose content. The results indicated that the addition of CS could be beneficial to the formation of an ordered molecular structure in LS-CS blends and decreased digestibility in vitro.

Hierarchical structure and slowly digestible features of rice starch following microwave cooking with storage

By inspecting starch hierarchical structural evolutions, this work explores how microwave cooking with storage tailors the slowly digestible features of indica (IRS) and waxy (WRS) rice starches. Particularly, relative to conventional cooking-storage, the microwave treatment especially at high powers (8 and 10 W/g) increased the molecular orders (crystallites) and periodic amorphous-crystalline structures. Such changes facilitated the formation of domains with intermediately-densely packed starch chains, being modestly accessible to the diffusion, absorption and catalysis of enzymes and dominantly showing slowly digestible features. Consistently, the microwave processed starches showed a higher SDS (slowly digestible starch) level and a lower digestion rate. This microwave-enhanced SDS generation became more prominent for IRS, and the treated IRS at 10 W/g showed the highest SDS content (ca. 54%). This is related to the enhanced reassembly of glucan chains into ordered/semicrystalline structures and the formation of slowly digestible domains as induced by the increase of amylose molecules.

The combined effects of extrusion and heat-moisture treatment on the physicochemical properties and digestibility of corn starch

The combined effects of extrusion (ET) and heat-moisture treatments (EHMT) on the physicochemical properties and in vitro digestibility of corn starch were investigated. Extrusion played a dominant role in reducing relative crystallinity and resistant starch (RS) content, but the swelling power, solubility, rapidly digestible starch (RDS) and slowly digestible starch (SDS) content were increased compared to native starch. EHMT resulted in a decreased swelling power, solubility and a transition in the X-ray diffraction from V- to V+A-type pattern, indicating a structural transformation toward an increased thermodynamic stability. The gelatinization temperatures shifted to higher values while the enthalpy was increased from 1.556 J/g in ET to 3.542 J/g in EHMT. The SDS and RS contents of starch granules were significantly increased, with the latter being increased from 63.03% in ET starch to 71.48% in EHMT starch.

Production of slowly digestible corn starch using hyperthermophilic Staphylothermus marinus amylopullulanase in Bacillus subtilis.

We describe a novel method for enzymatic production of slowly digestible starch (SDS) at 100 °C. A hyperthermophilic amylopullulanase from archaeon Staphylothermus marinus (SMApu) was expressed in a generally recognised as safe (GRAS) microorganism, Bacillus subtilis. Purified SMApu at 80-240 U/g substrate was incubated with 0.1 g/mL of corn starch in a boiling water bath for 2 h. SDS content of the SMApu-modified starch increased significantly from 17.4 to 42.7% (P < 0.05). Molecular weight and amylopectin branch chains A (DP 6-12) of SMApu-modified starch were significantly lower, and amylose content and amylopectin branch chains B1 (DP 13-24) significantly higher (P < 0.05), than those of natural corn starch. These changes in molecular structure partially explained the reduced digestibility. High optimal temperature of SMApu facilitated the simultaneous gelatinisation and hydrolysis of cereal starch. These results demonstrate that SMApu has potential applications in the production of SDS during thermal processing of cereal foods.

The effect of different thermal modifications on slowly digestible starch and physicochemical properties of green banana flour (Musa acuminata colla)

The effect of heat moisture treatment (HMT), annealing (ANN), and dual retrogradation (DR) on functional and pasting properties, digestibility of starch components of banana flour comprising rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) has been investigated, using native banana flour (NBF) as a control. Crystal type, relative crystallinity and morphological changes were characterised by XRD and SEM. HMT has markedly modified the pasting properties and resulted in the highest SDS content. HMT and ANN increased the relative crystallinity but DR decreased it. HMT and DR altered XRD patterns from B to A and A + B type respectively, while ANN did not change the XRD patterns. The NBF compact granule surface remained unchanged with ANN but changed to a more porous surface with HMT and DR, thereby increasing the digestibility. Crystal type and granule morphology affected the digestibility while relative crystallinity might change the pasting point.

In Vitro Starch Digestion and Colonic Fermentation of Thai Jasmine Rice

Resistant starch (RS) enhances gastrointestinal (GI) health but RS content in rice varies depending on cooking and storage conditions. Hydrolysis rates of in vitro starch fractions in simulated GI, colonic fermentation of freshly cooked Thai jasmine rice (control) by rice cooker method (RCM) and boiling method (BM), and reheated jasmine rice stored for 3 days at 4 and −20 °C are evaluated. Storage increased RS, slowly digestible starch (SDS) content of jasmine rice cooked by RCM, and SDS content of jasmine rice cooked by BM due to the decrease in rapidly digestible starch (RDS). The effect of storage on starch fractions in jasmine rice differed with temperature. For simulated GI conditions, 50.07% of jasmine rice hydrolysate escaped hydrolysis similarly among treatments. Jasmine rice hydrolysates selectively enhanced growth of probiotic strains but not pathogenic growth with time. Maximum specific growth rates (μmax, h−1) of strains were measured as Bifidobacterium animalis 2194 &gt; Bifidobacterium bifidum TISTR 2129 &gt; Lactobacillus reuteri AC‐5 &gt; Escherichia coli E010 ≥ Salmonella serovar Enteritidis S003. With regard to quantity and quality, jasmine rice hydrolysate was not affected by cooking and storage conditions but influenced by colonic fermentation.

Physicochemical, rheological, morphological, and in vitro digestibility properties of cross-linked starch from pearl millet cultivars

ABSTRACTThe effect of epichlorohydrin (0.5%) as a cross-linking agent on physicochemical, rheological, morphological, and in vitro digestion properties of pearl millet starches from different cultivars was studied. Degree of cross-linking (DC) ranged between 40.61% and 89.75%, lower values of DC were observed for cv.HC-10 and cv.HHB-67 whereas higher values were observed for cv.HHB-223 and cv.GHB-732. Cross-linked starch from cv.GHB-732 showed the lowest amylose content, swelling power, and solubility as compared to other cultivars. Rheological properties of starches during heating showed their elastic behaviour. G′ value was much higher than the G′′ value at all frequency values for starch pastes. Plots of shear stress (σ) versus shear rate (γ̇) data for cross-linked starch pastes were fitted to Herschel-Bulkley model and yield stress (σo), flow behaviour index (n), and consistency index (K) were evaluated. Scanning electron micrographs (SEM) investigations revealed that cross-linked starch granules had slightly rough surfaceand grooves with slight fragmentations. Readily digestible starch (RDS) of cross-linked starches varied from 46.1% to 50.6%, cv.GHB-732 had the lowest value. Slowly digestible starch (SDS) and resistant starch (RS) content of cross-linked starches ranged from 34.5% to 36.4% and 13.6% to 19.4%, respectively. cv.HC-10 had the highest value for SDS content while the highest RS content was observed for cv.GHB-732. In comparison to native starches, cross-linked modification decreased SDS and RDS content whereas RS content was increased.

In vitro digestion and physicochemical characteristics of corn starch mixed with amino acid modified by heat-moisture treatment

Corn starch was modified with amino acid by heat-moisture treatment (HMT) to investigate the formation of slowly digestible starch (SDS). SDS content in native corn starch and heat-moisture treated corn starch were 17.91% and 4.35% respectively, while the maximum SDS content in amino acid-heat treated starches (HMT-amino acid) reached 41.07%. HMT-Lys displayed reduced birefringence brightness at the periphery, while for HMT-Asp, a weaker birefringence region was observed but without apparent Maltese crosses. HMT-amino acid showed higher gelatinization temperature and lower gelatinization enthalpy. After HMT, relative crystallinity of amino acid-heat treated starches decreased. The lower ΔH and the lowest relative crystallinity had the highest SDS content (41.07%). The results indicated that structural changes of corn starch mixed with amino acid by HMT significantly affected the digestibility.

Effect of pulsed electric fields treatment on the nanostructure of esterified potato starch and their potential glycemic digestibility

Abstract Esterified starch macromolecules were studied in relation to the effects of pulsed electric fields (PEF) on in vitro digestibility and emulsion stability. The results show that starch acetates with higher electric intensity yielded emulsion with lower oil layer separation over a 30 days shelf life trial. The in vitro digestion suggests the quantity of slowly digestible starch (SDS) fractions increased from 6.63% in the control sample to 17.53% at 3.75 kV/cm. Scanning electron microscopy, X-ray diffraction, small-angle X-ray scattering and atomic force microscopy were used to determine the crystalline and nanostructure. The surface of native starch (as observed in the nanosheet images) exhibited a low roughness value (Ra = 0.639 nm), while starch acetates displayed an increase in surface roughness ((Ra = 0.766 nm (non-PEF) and 1.176 nm (PEF-combined)). The results illustrate that PEF has an important impact on the emulsification and SDS contents of potato starch granules. Industrial relevance Pulsed electric fields (PEF) are a technique widely used to improve the sterilization efficiency and help modify macromolecules. The present paper evaluates the potential applications of chemically modified potato starch molecules assisted by PEF process. Based on the investigation of the nanostructure and crystalline texture, the effect of PEF acted on esterificated starch macromolecules is proposed to explain these changes occurred to properties. The results have also demonstrated that the PEF treatment applied on esterification did promote the digestibility and emulsification stability of the product. Through the PEF treatment shows high potentials to be applied with esterification at an industrial level to enhance the reaction efficiency and to obtain novel products with better glycemic digestibility and emulsion stability.

Inter-laboratory validation of the starch digestibility method for determination of rapidly digestible and slowly digestible starch

The digestibility of starch in foods, which is influenced by the ingredients, formulation and preparation conditions, is a major determinant of glycaemic response. The terms rapidly digestible starch (RDS) and slowly digestible starch (SDS) along with the associated analytical methodology were developed by Englyst to characterise this nutritionally relevant food attribute. The measurement uncertainty of this starch digestibility method is evaluated here with an inter-laboratory trial. Six laboratories took part in the study testing ten cereal products with mean (range) contents of RDS: 48.4 g/100 g, (23.4–76·9) and, SDS: 10.9 g/100 g, (0.8–24.2). Based on the repeatability and reproducibility measurements, the calculated uncertainty was 3.6 g/100 g for RDS and 1.9 g/100 g for SDS. This trial has demonstrated acceptable measurement uncertainty and confirmed the transferability of the method between laboratories. The SDS content can identify foods rich in slow release carbohydrates with their associated health benefits.