Amberlite FPA OH^- Ion Exchange Resin

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.

Background and Objectives: In many countries, the Codex Alimentarius definition of dietary fiber has been adopted with the optional inclusion of oligosaccharides with a degree of polymerization (dp) of ≥ 3. These oligosaccharides are usually captured as low molecular weight soluble dietary fiber (LMWSDF). The suitability of the AOAC-method 2017.16 for the determination of LMWSDF was evaluated, focusing on the correct differentiation between LMWSDF and mono- and disaccharides using different groups of oligosaccharides. Findings: Desalting of LMWSDF with ion exchange resins resulted in an expected, almost complete loss of uronic acid-based oligosaccharides. Due to their elution behavior in size exclusion chromatography, pentotrioses (arabinotriose, xylotriose) were excluded from LMWSDF. Differently, 1,6-linked hexobioses such as melibiose eluted earlier than 1,4-linked hexobioses (such as the standard maltose) and were incorrectly captured as LMWSDF. Conclusions: A precise determination of LMWSDF content using AOAC-method 2017.16 depends on the sample to be analyzed. As LMWSDF cannot always be analyzed correctly, these data raise additional questions about the suitability of the dietary fiber definition.

Mexican hawthorn fruit (Crataegus mexicana), also known as Tejocote, is an underexploited native Mexican fruit. This study aimed to determine the composition, antioxidant activity, and moisture isotherms of dietary fiber concentrates (DFC) obtained from Mexican hawthorn fruit fractions (pulp, peel, and seed) to assess their suitability as food ingredients. High molecular weight and low molecular weight soluble, insoluble, and total dietary fiber (SDFP and SDFS, IDF, and TDF, respectively) were also determined. Some techno-functional properties were measured including water and oil retention capacity, solubility, and swelling capacity. The TDF content followed the order seed >peel> pulp (92.84 ± 0.81, 59.44 ± 1.43, and 48.38 ± 0.42 g·100 g⁻¹ db). The highest SDF:IDF ratio was found in pulp DFC (0.08:1), highly correlated with its techno-functionality. Conversely, phenolic content and antioxidant activity were higher in the peel DFC. GAB and Peleg models were more suitable for fitting the experimental data for moisture isotherms, which displayed a BET type III behavior for both adsorption and desorption. This study provides novel and supportive information for revalorizing Mexican hawthorn fruit as a potential ingredient in food and functional products.

Oat flour mixed with 30 g/100 g rice flour was extruded with a twin-screw extruder using a central composite orthogonal design. Temperatures (120°C,140°C, 160°C) and moisture (14.5 g/100 g, 17.7 g/100 g, 20.6 g/100 g) were adjusted during extrusion, while screw speed was kept constant (400 rpm). Extrudates were analysed for structure (expansion, density, microstructure), texture (hardness), β-glucan (molecular weight and extractability), as well as fibre content. Expansion varied between 250 and 329%, density between 165 and 457 kg/m³ and hardness between 27 and 64 N. The response surface model showed that more expanded, less dense and less hard extrudates were achieved at low moisture, while high temperature resulted in lower density and hardness. Significant differences in β-glucan extractability were observed depending on extrusion conditions, with values ranging between 0.64 and 1.31 g/100 g. β-glucan extractability correlated with positively with porosity, and negatively with moisture content during extrusion, cell wall thickness and density. The results indicate that conditions that produce a more porous, crispier structure, also increases β-glucan extractability.

The reliable determination of soluble, insoluble and total dietary fibre in baked goods and cereal flours is an important issue for research, nutritional labelling and marketing. We compared total dietary fibre (TDF) contents of selected cereal based foods determined by AOAC Method 991.43 and the new AOAC Method 2009.01. Fifteen bread and bakery products were included in the study. Our results showed that TDF values of cereal products determined by AOAC Method 2009.01 were always significantly higher than those determined by AOAC Method 991.43. This was explained by the inclusion of low molecular weight soluble fibre fractions and resistant starch fractions in the TDF measurement by AOAC 2009.01. This documents that nutritional labelling of cereal products poses the challenge how to update TDF data in nutrient databases in a reasonable time with an acceptable expenditure.