Starch Damage Assay Kit

Procedures for the measurement of starch, starch damage (gelatinised starch), resistant starch and the amylose/amylopectin content of starch, β-glucan, fructan, glucomannan and galactosyl-sucrose oligosaccharides (raffinose, stachyose and verbascose) in plant material, animal feeds and foods are described. Most of these methods have been successfully subjected to interlaboratory evaluation. All methods are based on the use of enzymes either purified by conventional chromatography or produced using molecular biology techniques. Such methods allow specific, accurate and reliable quantification of a particular component. Problems in calculating the actual weight of galactosyl-sucrose oligosaccharides in test samples are discussed in detail.

An American Association of Cereal Chemists/AOAC collaborative study was conducted to evaluate the accuracy and reliability of an enzyme assay kit procedure for measurement of total starch in a range of cereal grains and products. The flour sample is incubated at 95 degrees C with thermostable alpha-amylase to catalyze the hydrolysis of starch to maltodextrins, the pH of the slurry is adjusted, and the slurry is treated with a highly purified amyloglucosidase to quantitatively hydrolyze the dextrins to glucose. Glucose is measured with glucose oxidase-peroxidase reagent. Thirty-two collaborators were sent 16 homogeneous test samples as 8 blind duplicates. These samples included chicken feed pellets, white bread, green peas, high-amylose maize starch, white wheat flour, wheat starch, oat bran, and spaghetti. All samples were analyzed by the standard procedure as detailed above; 4 samples (high-amylose maize starch and wheat starch) were also analyzed by a method that requires the samples to be cooked first in dimethyl sulfoxide (DMSO). Relative standard deviations for repeatability (RSD(r)) ranged from 2.1 to 3.9%, and relative standard deviations for reproducibility (RSD(R)) ranged from 2.9 to 5.7%. The RSD(R) value for high amylose maize starch analyzed by the standard (non-DMSO) procedure was 5.7%; the value was reduced to 2.9% when the DMSO procedure was used, and the determined starch values increased from 86.9 to 97.2%.

A commercially available enzymatic assay kit for the measurement of starch damage in wheat flour was compared with current standard methods, and the kit's precision and repeatability were determined in a collaborative study. Starch damage values determined on a range of flours with the assay kit correlated well (r > 0.96) with those determined by existing standard enzymatic methods. The precision of the kit was evaluated in a comprehensive interlaboratory study. The kit procedure was found to be highly repeatable (relative standard deviation, 2.94-6.80%) and reproducible (relative standard deviation, 5.00-10.30%).

An improved enzymic method for the determination of starch damage in wheat flour has been developed and characterized. The proposed method is simple and reliable, and enables up to 20 samples to be measured in duplicate in 2 h. A single assay takes approximately 40 min. The assay protocol is in two phases. In the first, the flour sample is incubated with purified fungal alpha-amylase to liberate damaged starch granules as soluble oligosaccharides. After centrifugation, the oligosaccharides in the supernatant are hydrolysed by amyloglucosidase to glucose in phase 2. The glucose is then quantified with a glucose oxidase/peroxidase reagent. The proposed method therefore avoids potential errors associated with existing standard assays, which employ unpurified amylase preparations and non-specific reducing group methods to quantify the hydrolytic products. Despite the use of purified assay components, the proposed starch damage method did not exhibit an absolute end-point to the action of alpha-amylase in phase 1. This was due to a low rate of hydrolysis of undamaged granules, and is a feature of enzymic methods for starch damage determination. Other amylolytic enzymes, including beta-amylase, isoamylase and pullulanase, and combinations of these enzymes, were evaluated as alternatives to alpha-amylase in the proposed method. These enzymes, when used alone, gave no benefits over the use of alpha-amylase. When used in combination with alpha-amylase, there was a synergistic action on undamaged granules. A test kit based on the assay format described in this paper is the subject of an international interlaboratory evaluation.

This study investigated the effects of superheated steam (SS) treatment at different temperatures (120°C, 150°C, 180°C) on the physicochemical properties of broken rice flour and the quality of broken rice cakes. SS treatment at 120 °C significantly enhanced the moisture content of broken rice flour (P < 0.05). In contrast, treatments at 150 °C and 180 °C caused decrease of moisture content, amylose leaching, and reduction of damaged starch content. After SS treatment, the pasting properties of broken rice flour increased, along with the rising of storage modulus and loss modulus. The proportion of short chains (DP 6-12) in amylopectin increased from 29.42% to 34.80% (P < 0.05), which could delay starch retrogradation. Compared with untreated ones, the SS-150 broken rice cakes showed a significantly higher specific volume (2.96 mL/g, P < 0.05), more uniform cell structure, and lower hardness (1.66 N) and chewiness (10.22 mJ). After 7 days of storage, cakes from SS-treated rice flour (150°C and 180°C) had significantly reduced hardness and chewiness. The study demonstrated that SS treatment could improve the properties of broken rice flour and enhance the quality of broken rice cakes, especially at 150°C and 180°C. This study presents a method for improving the quality of broken rice flour and rice cakes using superheated steam treatment, addressing challenges related to poor flour characteristics and suboptimal cake quality. The findings offer technical and theoretical support for enhancing rice cake production, contributing to the comprehensive utilization of rice resources.

Despite being an effective and clean-label method, heat-moisture treatment (HMT) is not commonly used for starch modification in industry due to the difficulty of scale-up. This study aimed to develop a novel method of using extrusion combined with high-temperature drying (EHTD) as an alternative to HMT for starch modification. Pea starch was subjected to extrusion at 37.5% moisture level and with a low-temperature profile (≤ 65 °C), followed by immediate heating at 130°C for 1 h. EHTD significantly damaged the granules, altered the X-ray diffraction pattern, and reduced the relative crystallinity of pea starch. Overall, EHTD-modified pea starch exhibited increased gelatinization temperatures and decreased gelatinization enthalpy change, lowered pasting viscosity and gel hardness, as well as enhanced enzymatic resistance than the native pea starch. More importantly, in a human feeding trial (n = 20 healthy participants) to monitor plasma glucose response over a period of 2 h after consuming water-boiled sample (35 g starch, dry basis), EHTD-modified pea starch exhibited 22% reduction (p < 0.01) in plasma glucose incremental area under the curve as compared to the native counterpart. The results indicated that EHTD could be a new simple and clean-label method to produce functional and low-glycemic starch ingredients.

Aim is to explore the breadmaking potential for gluten-free goods of non-conventional starches from Andean crops ahipa, oca, and arracacha. Their characteristics and performance in breadmaking are compared with those of cassava, taken as a reference for conventional gluten-free root starch. Physicochemical properties of breads are studied along with the pasting and thermal properties, composition, and α-amylase hydrolysis of starches. Arracacha starch has the lowest amylose content (2.4%) and the highest water hydration (1.4 g g⁻¹). Its batter shows adequate proofing, but the bread is highly adhesive, with dense crumb. Ahipa starch paste has the lowest peak, trough and final viscosities determined by rapid visco analyzer, and the highest hydrolysis rate (k_RVA = 2.30 min⁻¹). Its batter exhibits, along with oca, the highest volume increase during fermentation (193–197%), but structure collapses in the oven and no alveoli are observed in the crumb. Conversely, oca forms a crumb structure similar to cassava, but with higher cell density (131 alveoli cm⁻²), cohesiveness (0.95), and resilience (0.65) than the latter (71 alveoli cm⁻², 0.88, and 0.45, respectively). Oca starch has lower pasting temperature (64°C) and the starch paste has similar hydrolysis rate (k_RVA = 1.92 min⁻¹) compared to cassava (71.9°C and 2.08 min⁻¹, respectively), making it a suitable option for providing gluten-free yeast-leavened breads with improved technological properties and a comparable glycemic index.

Gluten-free and gum-free breads were developed, with the focus on the impact of raw materials (rice grain or flour) and processing conditions (pre-hydration and mixing time). The evaluation of bread quality primarily involved after the measurement of specific volume (BV), alveolar area (AA), and crumb hardness both before and storage. BV varied within 1.99–2.97 ml/g for rice bread and 2.14–2.26 ml/g for flour bread, with control (containing xanthan gum) values of 2.65 and 3.11 ml/g for rice and flour bread, respectively. An increase in AA was observed (rice: 0.5–1.9 mm² and flour: 0.76–2.0 mm²) compared to controls with gum (rice: 0.36 and flour: 1.41 mm²). Pre-hydration of ingredients and reduced mixing time improved bread quality: volume of bread from hydrated rice and 4 min of mixing time was comparable to that of gum control. Although the aging process, measured by hardness, was faster than in gum-containing bread, process conditions were identified that delayed aging. This information is essential and valuable for future research.

Background and Objectives: This study aimed to compare the quality of purple whole wheat flours (WWFs), which exhibit various health benefits. An ultracentrifugal mill was used to prepare purple WWF samples from four distinct purple wheat cultivars (Ariheukchal, AC; Ariheuk, AH; Arijinheuk, AJ; and Sintong, ST) each with different kernel hardness values and amylose contents. Findings: The average particle diameter (d50) of the WWFs (ST < AJ < AH < AC) was positively correlated with the kernel hardness. The amylose contents of the WWFs increased in the order AC < AH < AJ < ST, whereas their solvent retention capacities (SRCs) in water and sodium carbonate solutions followed the reverse order, similar to the d50. SDS sedimentation volumes did not correlate with the protein contents. ST showed significantly lower total phenolic and anthocyanin contents and antioxidant activities than the other varieties. Conclusions: Kernel hardness and amylose content significantly influenced the particle size, damaged starch content, SRC, and pasting properties of the WWFs. Additionally, the nutritional components and antioxidant activities of AC, AH, and AJ suggested strong potential for diverse functional products.

Techno-functional properties of six sorghum types were determined during spontaneous sourdough batter-type fermentation for Kisra production. All sorghum types showed a progressive decrease in pH to about 3.3 with fermentation for 40 h, accompanied by an increase in titratable acidity and free amino nitrogen. Fermentation increased pasting viscosity at 16 and 24 h, but decreased at 40 h due to starch hydrolysis. Protein hydrolysis as shown by SDS-PAGE leads to disaggregation of flour particles and the release of starch granules to increase the pasting viscosity. Thus, starch was more freely available to absorb water to paste and produce a higher viscosity from zero to 40 h. The decrease in pasting viscosity from 24 h to 40 h of fermentation was related to starch hydrolysis, as there was a reduction in total starch in the batter and pitting of starch granules, as shown by scanning electron microscopy. Fermentation had a more significant effect on techno-functional properties than sorghum types. Low protein and high tannin contents among the sorghum type also showed higher pasting viscosity. The techno-functional changes of sorghum batter during fermentation, especially the high pasting viscosity, might be helpful for structure design of kisra and other gluten-free sorghum-based products.

The aim of this study was to evaluate the effect of freezing rates using direct (LF: Liquid nitrogen) and indirect (RF: Cryogenic refrigerator and UF: ultra-freezer) methods at temperatures of (−20, −80, and − 196°C) on the enzymatic susceptibility with α-amylase for microparticles. In vitro digestibility parameters and technological properties were also analyzed. Lower rates resulted in larger ice crystals, damaging the starch structure. Hydrolysis was more pronounced at slower rates RF: 0.07°C/min and UF: 0.14°C/min, yielding maximum values of RDS: 37.63% and SDS: 59.32% for RF. Type A crystallinity remained unchanged, with only a noted increase in crystallinity of up to 6.50% for FR. Starch pastes were classified as pseudoplastic, with RF exhibiting superior textural parameters and apparent viscosity. (RF: 7.18 J g⁻¹ and UF: 7.34 J g⁻¹) also showed lower values of gelatinization enthalpy. Freezing techniques were viable in facilitating the diffusion of α-amylase and reducing RS by up to 81%.

Breeding of intermediate wheatgrass (Thinopyrum intermedium, IWG) culminated in the release of a commercial cultivar (MN-Clearwater) with attractive environmental and nutritional benefits. Determining the impacts of ambient storage and common postharvest processing on the stability of IWG flour is essential to promote it as a food ingredient. Accordingly, MN-Clearwater and two other potential cultivars, selected for their unique chemical composition, were subjected to extrusion and germination followed by 8 months of storage. Antioxidants, lipase and lipoxygenase activity, free fatty acid (FFA), peroxide value (PV), and volatile odor compounds (VOC) were analyzed at different timepoints.

Pulsed electric field (PEF) technology was used to extract starch from Q. robur flours using low-intensity electric fields (0 and 0.1 kV/cm) and study the impact of PEF on the structure and properties of acorn starch concerning commercial starch. PEF technology is an advantageous method for starch extraction than the aqueous steeping from an industrial perspective since reduces extraction time and allows for continuous processing of larger suspension volumes. PEF technology preserved the amylose and amylopectin contents, hydrogen bonds, and diffraction patterns, as well as the starch native properties. Hence, PEF could be used to obtain native starches, but future studies should verify its economic viability. Acorn starches have lower damaged starch content, gelatinization temperatures, enthalpies, improved pseudoplastic behavior, reduced in-vitro digestibility, and lower resistance to deformation compared to commercial corn starch. The higher solubility and swelling power of acorn starches up to 80 °C make them a suitable food additive in fermented yogurt and milk products and thus help to value acorn and acorn starches. Hence, acorns can be used to obtain native starches, a food ingredient with a wide range of food and non-food usage, using PEF.

Wheat bran brings healthy properties in food products. However, its incorporation requires a first milling step during which it is subject to various loading modes which have an influence on its properties. This study investigated the influence of the loading modes (high shear or impact) generated by grinders during the milling on the hydration properties of common and durum wheat brans. An original study at molecular scale to target the distribution and intensity of hydration water bonds was carried out by gravimetric and spectroscopic methods. Results were analyzed in regards to the particle size distribution and shape factors as well as biochemical composition to highlight the process-structure-function relationships at macro and microscales. Impact grinder has a stronger effect on water vapor sorption capacity and FTIR multimer water at 3600 cm⁻¹ of durum wheat bran as well as a red shift in the band at 1030 cm⁻¹ related to a high decrease in residual starch crystallinity degree (about 17%). High shear grinder tends to increase the proportion of water strongly bound. Low field NMR analysis revealed differences in the high mobility water peak and a significant lower relaxation time T2 for native and ground durum wheat bran (up to 1.7 fold less).

Despite being rich in starch, over half of acorn production is undervalued. High hydrostatic pressure was used to modify the properties of Q. pyrenaica (0.1 and 460 MPa for 20 min) and Q. robur (0.1 and 333 MPa for 17.4 min) acorn starches to obtain high-valued ingredients. Pressure significantly altered the span distribution and heterogeneity of the acorn starch granules depending on the species, but their morphology was unaffected. Pressurization increased the amylose/amylopectin ratio and damaged starch contents, but the effect was more prominent in Q. pyrenaica than in Q. robur. However, the polymorphism, relative crystallinity, gelatinization temperatures, and enthalpies were preserved. The pressure effect on the starch properties depended on the property and species. The solubility, swelling power, and acorn gels’ resistance towards deformation for both species decreased after pressurization. For Q. pyrenaica starch, the in vitro digestibility increased, but the pseudoplastic behavior decreased after pressurization. No differences were seen for Q. robur. Regarding the commercial starch, acorn starches had lower gelatinization temperatures and enthalpies, lower in vitro digestibility, lower resistance towards deformation, superior pseudoplastic behavior, and overall higher solubility and swelling power until 80 °C. This encourages the usage of acorn starches as a new food ingredient.