Digestible and Resistant Starch Assay Kit

Background and objectives: The importance of selectively measuring available and unavailable carbohydrates in the human diet has been recognized for over 100 years. The levels of available carbohydrates in diets can be directly linked to major diseases of the Western world, namely Type II diabetes and obesity. Methodology for measurement of total carbohydrates by difference was introduced in the 1880s, and this forms the basis of carbohydrate determination in the United States. In the United Kingdom, a method to directly measure available carbohydrates was introduced in the 1920s to assist diabetic patients with food selection. The aim of the current work was to develop simple, specific, and reliable methods for available carbohydrates and digestible starch (and resistant starch). The major component of available carbohydrates in most foods is digestible starch. Findings: Simple methods for the measurement of rapidly digested starch, slowly digested starch, total digestible starch, resistant starch, and available carbohydrates have been developed, and the digestibility of phosphate cross‐linked starch has been studied in detail. The resistant starch procedure developed is an update of current procedures and incorporates incubation conditions with pancreatic α‐amylase (PAA) and amyloglucosidase (AMG) that parallel those used AOAC Method 2017.16 for total dietary fiber. Available carbohydrates are measured as glucose, fructose, and galactose, following complete and selective hydrolysis of digestible starch, maltodextrins, maltose, sucrose, and lactose to glucose, fructose, and galactose. Sucrose is hydrolyzed with a specific sucrase enzyme that has no action on fructo‐oligosaccharides (FOS). Conclusions: The currently described “available carbohydrates” method together with the total dietary fiber method (AOAC Method 2017.16) allows the measurement of all carbohydrates in food products, including digestible starch. Significance and novelty: This paper describes a simple and specific method for measurement of available carbohydrates in cereal, food, and feed products. This is the first method that provides the correct measurement of digestible starch and sucrose in the presence of FOS. Such methodology is essential for accurate labeling of food products, allowing consumers to make informed decisions in food selection.

This study optimised the production of starch nanoparticles (SNPs) from cassava, quinoa, and faba bean starches using a combined gelatinisation-ultrasound treatment. Response surface methodology with a Box-Behnken design was used to optimise ultrasound parameters (power: 140-700W, sonication time: 10-30 min, and starch concentration: 1-5%). Optimised conditions (420W, 20 min, 3% concentration) effectively produced uniform nanoparticles (65.7-87.6 nm) with narrow size distributions (PDI: 0.317-0.410) across all three botanical sources, achieving a substantial 99.7% reduction in particle size compared to native granules. The modified SNPs displayed altered crystallinity patterns (transitioning from type-A and C to type-V) with significantly reduced relative crystallinity (60-65% reduction) and amylose content (29.6-58.7% reduction), while maintaining their fundamental chemical structure as confirmed by FTIR and NMR analyses. Notably, the SNPs exhibited substantially increased water solubility (95.1-98.2% compared to 5.3-10.4% for native starches), improved oil absorption capacity (87.2-105.5% versus 58.9-69.5%), and significantly increased slowly digestible starch fractions (up to 63.8% in faba bean SNPs). This optimised treatment provides a sustainable, chemical-free method for producing functional starch nanoparticles with tailored digestibility profiles and enhanced technological properties for diverse food applications.

The aim of this study was to substitute wheat flour with barley, buckwheat and lupin flour mixture to design nutritional bread formulation that meets expectations of today's consumer. However, storage stability of such flour mixtures is problem for manufacturers. The effect of microwave (MW) treatment (350 W-700 W power levels and 30s–90s–150s exposure times) on flour and bread properties was investigated to overcome this problem. Bread with maximum specific volume and minimum hardness was obtained from formulation of 10% barley flour, 37.5% buckwheat flour and 2.5% lupin flour by using D-optimal mixture design. The lowest free fatty acid and total yeast-mold were obtained from 700 W-150s treatment. MW treatment increased total phenolic content and antioxidant activity while decreased total yeast-mold of flours and breads. Although MW treatment increased hardness of breads, no statistically significant difference was found between specific volume, springiness, cohesiveness, chewiness, water evaporation enthalpy.

The objective of this study was to investigate the impact of 24‐ and 48‐h germination on antinutrient levels (phytic acid, trypsin inhibitors, saponins, and tannins), in vitro starch and protein digestibility, and the content and bioaccessibility of phenolic compounds and antioxidants in chickpeas, peas, mung beans, and lentils. Germination resulted in reductions of phytic acid by up to 75.65% and trypsin inhibitor activity by up to 39.20% in the pulses studied. In contrast, saponin levels showed a significant increase, rising nearly threefold with germination, while mung beans exhibited an exceptional 27‐fold increase. Tannins decreased in lentils (2.6‐fold) and mung beans (5.8‐fold), increased in peas (1.6‐fold), and remained unchanged in chickpeas following germination. In vitro protein digestibility generally increased with germination, reaching up to 4.40%, except in peas, where a decline was observed. Germination significantly enhanced total digestible starch content while reducing resistant starch in all pulses except chickpeas. Mung beans exhibited the highest total phenolic content and antioxidant capacity, followed by lentils. Although germination significantly elevated total phenolic content in all pulses, this increase did not always align with antioxidant capacity outcomes. Additionally, germination led to a decline in the bioaccessibility of phenolics. However, the amount of phenolic compounds progressively increased during gastric and intestinal digestion, with intestinal digestion further enhancing the total antioxidant capacity of the pulses.

This study investigates the potential of superheated steam (SS) as a rapid and sustainable method for synthesising millet starch citrates with improved physicochemical and functional properties. Millet starch was esterified with citric acid (CA) under varying SS conditions (160-180°C, 15-45 min) to optimise the degree of substitution (DS) and evaluate its influence on starch functionality. A range of DS values (0.023 to 0.121) were achieved, with the highest DS observed at 170°C for 45 min. Structural analysis using Fourier-transform infrared spectroscopy confirmed successful esterification, with the appearance of a new peak at 1735 cm⁻¹ indicating ester bond formation. X-ray diffraction showed a reduction in crystallinity with increasing DS, while polarised light microscopy and confocal scanning laser microscopy revealed alterations in molecular organisation. Scanning electron microscopy demonstrated minimal disruption to granule morphology. Contact angle measurements indicated increased hydrophobicity, with water contact angles rising from 29.63° in native starch to 71.63° in high DS samples. Additionally, a significant (p < 0.05) reduction in amylose content and paste viscosities was observed, correlating with improved resistance to gelatinisation and retrogradation. In vitro digestibility analysis showed a substantial increase in resistant starch content, from 18.69% in native starch to 40.11% in high DS samples. These findings highlight SS as an efficient and eco-friendly technology for producing starch citrates with tailored functionalities, particularly suited for low-glycaemic response and health-promoting food applications.

The aim of this research was to assess nutritional and technological features of a traditional cereal-based baked product: Apulian Taralli. Three different formulations were studied for this product, evaluating the protein composition and the rate of protein aggregates formation, through electrophoretic and chromatographic approaches. Additionally, two different production technologies were compared, highlighting that technological process affects the protein extractability. Based on our knowledge, no other researches were focused on the analysis of this typical product from this perspective. The overall outcomes of the study provided new information on the protein organization for baked products, assessing the formation of high molecular weight protein aggregates, characterized by a different extractability and suggesting the need of testing different buffers to optimize the extraction conditions to deepen the organization of the protein network in baked products. Finally, the rate of starch digestion and the predicted glycemic index were measured, revealing how the two employed production technologies influenced also the nutritional features, obtaining promising outcomes for the formulation and production of a low-glycemic index cereal-based baked product, since the application of a patent technology allowed to have a final product with a low predicted glycemic index (pIG=48) for the three tested formulations.

Background: Legumes are a key component of the human diet and a primary source of plant‐based protein. They have attracted global attention as potential plant‐based meat alternatives due to their numerous health benefits, and they contribute to a more sustainable and healthy food system. Among pulses, peas (Pisum sativum L.) are considered a good source of proteins, fibers, starch, minerals, and vitamins. This study evaluated the effect of environmental conditions on nutritional profile of peas cultivated in an organic farming system, in different Italian environments (mountainous and hilly), during different cultivation years (2021 and 2022). Pea grain from peas cultivated under the various conditions was used to prepare pea‐based crackers containing 6% pea flour. The appearance, physical properties (rheology and texture), and nutritional profile of the snacks were evaluated, and sensory analysis was conducted. Results: The nutritional and bioactive compounds were strongly related and the environment exerted a substantial impact on most of the nutritional components (proteins and carbohydrates), due to climatic conditions during the vegetative and reproductive stage of the crop. The incorporation of cultivated peas into wheat‐based crackers improved their functional and nutritional quality while maintaining consumer acceptability, as demonstrated by sensory analysis. Conclusions: The results confirmed that growing conditions significantly influence the nutritional composition of peas, enhancing their quality and that of the resulting crackers. This aligns with the increasing global demand for high‐quality, sustainable food products.

The combined effects of extrusion and enzymatic hydrolysis with a neutral protease (endoprotease) on quinoa germ flour have been studied in this work. A 2 × 3 factorial design with two temperature levels (60°C-90°C-100°C and 60°C-100°C-120°C) and three protease concentrations (0 %w/v, 0.6%w/v, 1.2 %w/v). The hydrolyzed quinoa germ flours were characterized in terms of their physicochemical and rheological properties, antioxidant capacity by ABTS+, in-vitro digestibility of carbohydrates and protein, infrared spectroscopy, and their rheological behavior in aqueous dispersion at 12% (w/w). The results showed that enzymatic hydrolysis and extrusion temperature influenced hydrolyzed quinoa germ flours properties. The highest protein digestion (65 mg leucine/g protein) was obtained with 0.6% protease and 100°C extrusion. Antioxidant activity increased with protease concentration but decreased with temperature. The solubility of hydrolyzed quinoa germ flours improved after enzymatic hydrolysis, while water absorption decreased. The treatment with 0.6 % protease and 100 °C extrusion produced high amounts of slowly digestible starch and RS, and enhanced protein digestibility compared to the other treatments. Infrared spectroscopy revealed changes in amide functional groups A, B, and I due to hydrolysis. The modification of these flours through enzymatic hydrolysis and extrusion after the tecno-functional properties. This research highlights the importance of understanding the interactions between different sources of proteins and how they contribute to the overall characteristics of the final product.

This study investigated the effects of the physicochemical properties of filled hydrogels based on rice flour with varying amylose contents on the stability of encapsulated vitamin D₃ (VD, cholecalciferol). The filled hydrogel, prepared based on Saemimyeon with an amylose content of 25.5%, formed a gel with strong elasticity, showing the highest stability during in vitro digestion, as well as excellent pH and storage stability of the encapsulated VD. Dodamssal, which had the highest amylose content (> 40%) and gelatinization temperature, retrograded rapidly due to its high leached amylose content. This phenomenon caused gel shrinkage and subsequent emulsion leakage, resulting in a relatively lower VD retention rate after in vitro digestion compared to the Saemimyeon-based filled hydrogel. Nevertheless, compared to the emulsion system, the rice flour-based filled hydrogels formed various types of gel matrices that provided a physical barrier to the VD-containing lipid droplets, thereby significantly protecting them from the external environment.

This study investigated the effect of grape seed (GSd) and grape skin (GSk) tannins on the physicochemical, rheological properties and in-vitro digestibility of starches (corn, pea and wheat) derived from three different botanical sources. Quantification of bound and unbound tannins using MCP and HPLC analysis demonstrated that majority of the tannins were bound to starch molecules. The results of particle size distribution, starch-iodine binding and FTIR studies indicated the development of inclusion complexes through hydrophobic interactions with tannins in pea starch, while other two starches prominently formed non-inclusion complexes via hydrogen bonding. Back extrusion analysis of textural properties indicated that wheat starch-tannin complexes resulted in firmer starch-tannin gels compared to other two starches. Rheological studies revealed an increase in the viscoelastic modulus (G’ and G”) with improved elastic behavior for all starch-tannin gels. Starches complexed with tannins demonstrated strong antioxidant properties and in-vitro starch digestion studies revealed significant reductions in rapidly digestible starch (RDS) and slowly digestible starch (SDS), along with an increase in resistant starch (RS), particularly in pea starch complexed with GSd tannins. This study enhanced our understanding of how GSd and GSk tannins influence the properties of starches from various botanical origins, helping in understanding starch-tannin interactions and enabling the creation of foods with improved texture and digestibility.

Starch and proteins interact non-covalently by hydrogen bonding, electrostatic and hydrophobic interactions. While their impact on crumb stability in conventionally baked breads has been explored, the role of these interactions when using alternative baking technologies remains understudied. This study aimed to determine how non-covalent interactions affect rheological, nutritional and technological properties of gluten-free (GF) bread when baked using a deck oven or ohmic heating (OH). A GF formulation composed of maize starch and six structurally different non-gluten proteins was tested. Rheological and pasting properties, bread volume and starch digestibility were evaluated to study the significance of these interactions. Batter analyses indicated that protein functionality, particularly free sulfhydryl groups and surface hydrophobicity, strongly influenced pasting. Critical strain (0.09–0.14%) and flow transition points (1.01–3.69%) varied with protein type, showing distinct microstructural variations within the batter. Non-covalent interactions, especially hydrophobic and electrostatic forces, played a major role in stabilizing the OH bread, while conventional baking probably relied more on covalent interactions. Hydrogen bonding between polymers contributed to an increase in resistant starch (RS). This study revealed that specific non-covalent interactions played a crucial role in the structural and nutritional properties of GF bread, particularly when applying OH.

Germination is a sustainable and economical process that can enhance the bioactivities of commonly consumed cereal and pulses, contributing to healthier diets. Its effectiveness in increasing bioactives depends on the germination conditions. This study examined the impact of varying germination periods (2, 4, 6, and 8 days) following 12 h of steeping on rice, maize, green gram, and soy, focusing on key bioactive compounds, including total polyphenols, flavonoids, and total digestible starch. Cereal and pulses germinated for eight days demonstrated a significantly higher (P < 0.05) total polyphenol and flavonoid content along with elevated antioxidant activity. Antioxidant activity strongly correlated to increased total polyphenol and flavonoid levels throughout the extended germination period. Moreover, the total digestible starch content (TDS) in rice, maize, and soy increased significantly (P < 0.05) because of the hydrolysis of starch molecules, while green gram showed twofold decrease in TDS, indicating the impact of germination on TDS content may differ across the type of cereal and pules. Using locally grown Sri Lankan grain varieties, such as rice, maize,green gram,and soy, this study fills the gap in existing database on the investigation of bioactive compounds and total digestible starch content, exploring the potential of germination of cereal and pulses to use in nutritionally rich products in the food and agriculture industry with a focus on sustainable food systems and healthier eating habits.

Sprouted wheat wholemeal was reported to enhance the nutritional and sensory properties of cereal products, but few human studies exist. The effect of blending 50 % sprouted wheat wholemeal in a bread recipe on the postprandial glycemic and satiety responses, and sensory-related sensations was investigated in this randomized crossover human study with 12 healthy participants. Capillary blood samples were collected and glycemic response was determined at 0, 15, 30, 45, 60, 90, 120 min. Satiety visual analogue scales were given every 30 min. While substituting bread wheat flour with sprouted wheat wholemeal significantly increased the α-amylase activity in the dough (p < 0.05), it did not alter in vitro digestibility or postprandial glycemic and satiety responses (p > 0.05). Likewise, participant overall acceptability was not adversely affected. Sprouted wheat wholemeal can be used as a functional ingredient in breadmaking, although it did not, in this study, significantly affect digestibility parameters.

Sorghum (Sorghum bicolor L. Moench), characterized by substantial genetic diversity, encompasses some lines rich in health-promoting polyphenols. Laboratory studies have demonstrated anticancer properties of sorghum phenolics; however, their presence may impact nutritional factors, such as digestible starch. The objective of this study was to determine the effects of pH and high-moisture heating on starch digestibility, phenolic profile, and anticancer activity in sorghum. High Phenolic sorghum flour line SC84 was combined with buffer solutions (pH 3, 4, 5, 7, and 8) and heated for 0, 10, 30, 60, or 120 min. Starch digestibility was assessed using the K-DSTRS kit from Megazyme. Changes in phenolic composition were analyzed using total phenolic content (TPC) and condensed tannin content (CTC) assays coupled with reversed phase high performance liquid chromatography (RP-HPLC) analysis. Anticancer potential against human colorectal cancer cells (HCT116 and SW480) was determined though cell viability assay. Results indicated a significant increase in total starch digestibility of sample after heating. Heating samples for 10 min did not significantly reduce TPC of samples. However, CTC was significantly reduced with heating time, while pH exhibited no significant effect on CTC. The measured 3-deoxyanthocyanidins experienced a significant decrease (p < 0.0001), while certain flavonoids increased significantly (p < 0.05) after heating for 30 min or longer. Notably, the 10 min heating duration minimally affected anticancer activity, whereas longer heat times diminished extract efficacy against human colorectal cancer cells. Alkaline pH levels significantly decreased anticancer activity, regardless of heating time. Importantly, heating sorghum for 10 min improved starch digestibility with minimal compromise to potential health benefits. These findings suggest promising implications for the development of high-phenolic sorghum products, and provide valuable insights to guide forthcoming animal and clinical studies. The demonstrated impact of wet-heating on increased starch digestibility, coupled with the preservation of phenolic content and bioactivity, underscores the potential of incorporating high-phenolic sorghum lines in future functional food formulations.

Frequent consumption of processed, high-glycemic, low-fiber foods is associated with an increased risk of hyperglycemia, hyperinsulinemia, and ultimately of type-2 diabetes. This work investigated the impact of enriching high-glucose doughs with citrus fiber and various processing methods (baking and extrusion cooking) on glycemia using a novel combination of in vitro and in vivo methodology and relating to product-specific characteristics. Starch digestibility, dietary fiber composition, product structure and in vitro glucose release were determined. In vivo glycemia and insulinemia were evaluated in 11 adults at metabolic risk in a randomized, double-blind crossover study. The fiber-enriched products significantly reduced in vitro glucose release by up to 15%. Extrusion at 180°C increased soluble and total dietary fiber contents by 10 % and resistant starch content by 60%, impairing in vitro glucose release. Neither fiber-enrichment nor processing methods significantly influenced postprandial glucose and insulin concentrations in study participants emphasizing the need for combined developmental approaches.