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.

Coconut oil, rice bran oil and sunflower oil were added to rice, corn, banana and mung bean starches and the effect on physicochemical properties, amylose-lipid formation and digestive properties were investigated. Starch samples were heated while oil was added and starch treated without oil addition served as the control. Starches with different botanical origins complexed diversely with vegetable oils. The RDS content in corn and rice starches with oil addition decreased, while SDS and RS fractions increased. By contrast, the RS content of treated banana and mung bean starches decreased compared with native starch but RS and SDS contents increased when oil was added compared with the control sample. The A-type crystalline polymorph of corn and rice starches changed to a mixed A + V form, whereas native mung bean (C_(A)-type) changed to B-pattern and banana starch remained unchanged (B-type). FTIR spectra indicated new peaks corresponding to starch-lipid complexes. Starches added with oils and the control showed lower peak viscosity, trough viscosity final viscosity and setback but higher pasting temperature and delayed pasting time compared to native starch. Heat-moisture treatment with added vegetable oil showed promise as a process to prepare functional starch high in SDS and RS.

In recent years, resistant starch (RS) and slowly digestible starch (SDS) have been linked to the prevention of chronic noncommunicable diseases, such as obesity and its complications. Southern Mexico has an important role in the tuber crop production of M. esculenta and I. batatas, which contain considerable amounts of starch. The aim of this study was to evaluate the morphological and physicochemical changes of M. esculenta and I. batatas after pyrodextrinization, including the production of RS and SDS. The factors used in this study were the starch/acid ratio (2.2 HCl) (80:1 and 160:1 p/v); temperature (90°C and 110°C) and reaction time (1 and 3 h). The highest production of RS in M. esculenta was obtained with the highest starch/acid ratio and temperature, and the lowest reaction time. For pyrodextrins, loss of crystallinity and an increase in swelling power and water absorption capacity were observed. The highest production of RS in I. batatas was obtained with the highest starch/acid ratio and reaction time, and the lowest temperature. Crystallinity and enthalpy of gelatinization decreased in modified starches. The solubility, swelling power and water absorption capacity increased in both sources.

Microwave-assisted infrared is an emerging green technology that can be used in the thermal processing of lentils to modify their functional and nutritional properties as high-value plant-based protein ingredients. The study employed this technology to heat lentil seeds tempered to three higher moisture contents to produce modified flours. The influence of thermal process conditions on the starch structure was evaluated by reducing the degree of order through gelatinization, and the protein structure was assessed through denaturation, which led to the decline in the ordered structure of protein, β-band and α-helix, and the rise in the aggregated intermolecular structure, β-I, and unordered structure, random coil. Results showed that seeds tempered to the highest moisture content, 50%, and processed in higher thermal intensities, by the rise in microwave power and infrared combinations, experienced a higher degree of starch gelatinization and protein denaturation, improving the water holding capacity while reducing protein solubility. Particle size distributions and scanning electron microscopy analyses illustrated that thermal treatment eased the milling process in breaking down coarse particles. The modification process was also an effective way to improve nutritional properties by increasing in vitro starch and protein digestibility.

We previously observed beneficial effects of native banana starch (NBS) with a high resistant starch (RS) content on glycemic response in lean and obese participants. Here, we aimed to determine the effects of NBS and high-amylose maize starch (HMS) on glycemic control (GC) and glycemic variability (GV) in patients with type 2 diabetes (T2D) when treatments were matched for digestible starch content. In a randomized, crossover study, continuous glucose monitoring (CGM) was performed in 17 participants (aged 28-65 years, BMI ≥ 25 kg/m², both genders) consuming HMS, NBS, or digestible maize starch (DMS) for 4 days. HMS and NBS induced an increase in 24 h mean blood glucose during days 2 to 4 (p < 0.05). CONGA, GRADE, and J-index values were higher in HMS compared with DMS only at day 4 (p < 0.05). Yet, NBS intake provoked a reduction in fasting glycemia changes from baseline compared with DMS (p = 0.0074). In conclusion, under the experimental conditions, RS from two sources did not improve GC or GV. Future longer studies are needed to determine whether these findings were affected by a different baseline microbiota or other environmental factors.

Wheat flour was substituted by flour from roasted chickpeas at 10-20% (flour basis) and a multi-instrumental analytical approach was employed to explore the dough rheological behavior of the composite starch-proteins hydrated networks, the quality attributes of the resultant breads, as well as the staling process. Fortifications with roasted chickpea flour at 15 and 20% level significantly increased dough viscosity and elasticity as showed by oscillatory and creep-recovery rheological tests, implying higher dough resistance to flow and deformation that resulted in breads with significantly lower specific volumes and harder crumb than the control (bread without chickpea flour). Moreover, at 20% substitution level, the staling kinetics of composite breads, as monitored by texture profile analysis, indicated a greater extent of crumb hardening at the end of storage, whereas the level of retrograded amylopectin in the crumb as assessed by calorimetry (DSC) did not differ among samples. Nevertheless, for bread with 20% chickpea flour, FTIR spectroscopy revealed a large increase in protein β-sheets and a further increment of such conformational change in the stored crumb, suggesting dehydration of gluten and its involvement in the staling process. Instead, formulations with 10% roasted chickpea flour did not exhibit any major influence on dough rheological behavior, as well as on textural attributes and bread staling. Furthermore, at 10% substitution of wheat flour by roasted chickpea flour, there was complete masking of the “grass-like” and reduced “beany" and "earthy” off-flavor notes in breads, as assessed by a trained panel, pointing to a product with high overall acceptability.

The objective of the present work was to produce dog foods from a single recipe at three levels of resistant starch (RS). The low (LS), medium (MS), and high shear (HS) foods were produced on a single-screw extruder at target screw speeds of 250, 375 and 460 rpm, respectively, and with increasing in-barrel moisture as shear decreased. Post-production, kibble measurements and starch analyses were conducted. Kibble parameters were compared by ANOVA with significance noted at p < 0.05 with a single degree of freedom orthogonal contrasts for extrusion outputs, starch analyses, and viscosity (RVA). The MS and LS kibbles exiting the extruder were denser and less expanded (p < 0.05) than the HS treatment. Resistant starch, starch cook, and raw:cooked starch RVA AUC increased linearly as shear decreased. These results confirmed that lower mechanical energy processes led to decreased starch gelatinization and greater retention of in vitro RS.

Animal models indicate that butyrate might reduce motor symptoms in Parkinson’s disease. Some dietary fibers are butyrogenic, but in Parkinson’s disease patients their butyrate stimulating capacity is unknown. Therefore, we investigated different fiber supplements’ effects on short-chain fatty acid production, along with potential underlying mechanisms, in Parkinson’s patients and age-matched healthy controls. Finally, it was investigated if this butyrate production could be confirmed by using fiber-rich vegetables. Different fibers (n = 40) were evaluated by in vitro fermentation experiments with fecal samples of Parkinson’s patients (n = 24) and age-matched healthy volunteers (n = 39). Short-chain fatty acid production was analyzed by headspace solid-phase micro-extraction gas chromatography-mass spectrometry. Clostridium coccoides and C. leptum were quantified through 16S-rRNA gene-targeted group-specific qPCR. Factors influencing short-chain fatty acid production were investigated using linear mixed models. After fiber fermentation, butyrate concentration varied between 25.6 ± 16.5 µmol/g and 203.8 ± 91.9 µmol/g for Parkinson’s patients and between 52.7 ± 13.0 µmol/g and 229.5 ± 42.8 µmol/g for controls. Inulin had the largest effect, while xanthan gum had the lowest production. Similar to fiber supplements, inulin-rich vegetables, but also fungal β-glucans, stimulated butyrate production most of all vegetable fibers. Parkinson’s disease diagnosis limited short-chain fatty acid production and was negatively associated with butyrate producers. Butyrate kinetics during 48 h fermentation demonstrated a time lag effect in Parkinson’s patients, especially in fructo-oligosaccharide fermentation. Butyrate production can be stimulated in Parkinson’s patients, however, remains reduced compared to healthy controls. This is a first step in investigating dietary fiber’s potential to increase short-chain fatty acids in Parkinson’s disease.

Since starch is the major energy source of the human diet, retarding starch digestion could serve as an effective way for modulating glycemic response and for the prevention and treatment of obesity. In this study, a dietary bioactive compound, ascorbyl palmitate (AP), was evaluated as a potential inhibitor in the digestion of raw, cooked, and retrograded high amylose maize starch (HAMS) and potato starch (PS). The inhibitory effect of AP was compared with that of palmitic acid (PA), without the ascorbyl group. In addition, HAMS inclusion complexes with AP and PA were formed and treated by annealing (ANN), acid hydrolysis (ACH), and the combination of both. Upon the addition of AP, the resistant starch (RS) contents in raw, cooked, and retrograded starches were increased significantly, indicating the inhibitory effect of AP against starch digestion. Although both HAMS-AP and HAMS-PA inclusion complexes exhibited minimal RS contents, all the hydrothermal treatments enhanced the RS contents in both inclusion complexes, marking their potential to serve as a new type of RS, i.e., RS5. Among the treatments, ANN followed by ACH (ANN-ACH) was most effective to retard starch digestion by increasing RS contents. The study findings could have practical implications in designing functional starch-based ingredients and increasing their nutritional value.

With the changing of lifestyles globally, the demand for ready-to-eat (RTE) foods has increased. However, most of these RTE foods have been associated with intermediate (55-70) to high glycaemic index (GI) (>70) linked to high incidences of type 2 diabetes. Nyandarua County in Kenya is a major producer and consumer of potato and has the second highest type 2 diabetes prevalence (10.8%). Therefore, there is need to investigate whether there is a relationship between the potato and potato products consumed and the high type 2 diabetes prevalence. Total phenolic content (TPC), dry matter, and the levels of rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) may vary depending on potato variety and the form of the product, and may affect the rate and extent of starch digestibility, which affects the GI. This study investigated the effects of variety and processing method (product form) on the levels of TPC, dry matter, RDS, SDS, RS and GI in chips and crisps prepared from 3 potato varieties (Shangi, Dera mwana and Dutch Robijn). Potato variety significantly affected TPC, RDS, SDS and GI but did not significantly affect RS (p>0.05). Processing method results in different product forms which significantly affected dry matter content and GI (p<0.05). Higher levels of TPC and lower scores of GI were found in chips and crisps prepared from Dera mwana variety. Significant positive correlation relationships were observed between GI, and RDS and SDS (p < 0.05), and RDS and SDS (p<0.05). This study recommends reduced consumption of chips prepared from Shangi in favour of Dera mwana variety which has better potential for glycemic control.