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.

The present study investigated the effects of milling conditions, particle size, and wheat variety on the properties of whole-wheat flour (WWF) and its performance in baking dough- and batter-based sweet goods. Two milling methods, ultra-centrifugal and cutting milling, were used to produce WWFs with varying particle sizes (four groups) from two wheat varieties, Goso (GS) and Joongmo (JM). WWFs with smaller particle sizes (two groups) exhibited higher damaged-starch content and pasting viscosities, which benefited batter-based sweet goods such as muffins by increasing their volume. In contrast, larger particle sizes (two groups) were associated with lower damaged-starch content and pasting viscosities, favoring dough-based sweet goods such as cookies by yielding larger diameters and smaller heights. Although the wheat variety influenced the cookie- and muffin-making performance, its impact was less significant than the particle-size variations resulting from milling. GS WWFs demonstrated equal or marginally superior performance compared to JM WWFs in both batter- and dough-based sweet goods. In summary, the particle size exhibited a more pronounced effect on the baking performance of sweet goods than the wheat variety. These findings highlight the critical role of milling conditions and particle size in optimizing the functional properties of WWFs for diverse baking applications.

This study investigated the effects of three structurally similar oligosaccharides, stachyose (STA), raffinose (RAF), and sucrose (SUC), with prebiotic activity on the rheological properties of wheat starch subjected to various freezing rates. The results demonstrated that these oligosaccharides effectively inhibited ice crystal growth and protected starch granules through hydrogen bonding. STA, with a long-chain structure (DP = 4) and high hydroxyl density, reduced the freezable water content by forming a three-dimensional hydration network, minimizing the ice crystal volume, and stabilizing the double-helix structure. RAF (DP = 3) exhibited a moderate protective effect, whereas SUC (DP = 2) notably inhibited starch swelling, owing to its small molecular size. Furthermore, STA decreased the storage and loss moduli, reduced viscosity and shear stress, suppressed retrogradation, and enhanced the overall system stability. These findings reveal that oligosaccharides specifically interact with wheat starch by binding to water under various freezing conditions. The selection of appropriate oligosaccharides can regulate both the anti-retrogradation and rheological properties of frozen starch, offering a molecular design strategy for optimizing the quality of frozen food.

Companies face challenges in transforming pulse grains into powders. The current practice of pulse millers remains largely empirical and scientific expertise in pulse grinding is required. This study investigates the impact of cylinder configuration, rotation speed and speed ratio settings on the properties of pea powder, using a laboratory roller mill. The aim is to provide a comprehensive description of the effects of the grinding process parameters on the granulometric characteristics, damaged starch content and hydration behavior of pea powders. The present study proposes an original approach to describe particle sizes distribution curves for pea powders, taking into account the systematic presence of 3 different particle populations of particles that differ in size and composition. Experimental design and response surface methodology were used to manage the approach and to analyze the results. Different pea powders of similar composition were produced by modifying the grinding conditions. The findings indicated that the use of splined cylinders improves the fragmentation mechanisms and the release of subcellular components, increasing the proportions of fine and very fine particles in pea powders. In addition, the contribution of particle populations on pea powder hydration behavior is dependent on the degree of hydration.

This study investigated the effects of mill type, milling conditions, and wheat variety on the mean particle size, particle size distribution, and quality characteristics of whole wheat flour (WWFs). Three wheat varieties (Goso [GS], Hojoong [HJ], and Joongmo [JM]), representing varying protein contents, were milled using two types of mills: an ultra-centrifugal mill (UM) and a cutting mill (CM). The milling conditions were adjusted based on the sieve openings (0.5 and 1.0 mm) and rotor speeds (UM: 6000 and 14,000 rpm; CM: 2000 and 4000 rpm). The mean particle size and particle size distribution of the WWFs were significantly influenced by the mill type, milling conditions, and their interactions. UM and CM produced distinct particle size distributions, with CM yielding a broader range and a more pronounced bimodal distribution. Furthermore, the type of mill and milling conditions, along with their interactions, affected the damaged starch content, water and sodium carbonate solvent retention capacity, pasting properties, and antioxidant activity of the WWFs. The wheat variety influenced parameters such as moisture, ash, damaged starch content, sodium dodecyl sulfate sedimentation volume, rapid viscoanalyzer (RVA) pasting properties, total phenolic content, and antioxidant activity. Notably, selecting an appropriate mill type and milling conditions is critical for producing WWFs with high gluten strength from high-protein wheat varieties.

This research investigated the changes in physiochemical and techno-functional properties, protein nutritional quality, and microbial properties of Canary seed flour following hydrothermal treatment. Four hairless Canary seeds were dehulled, steamed, dried, and ground to flour. The hydrothermal treatment increased the mean particle size (~80 %), damaged starch content (~260%), and water absorption capacity (~46 %), while not affecting the flour’s acidity (pH ~6.4), bulk density (~0.6 g/mL), or oil absorption capacity (~2.0 %). Hydrothermal treatment affected all the pasting and thermal properties of Canary seed flour except for the pasting temperature. Nutritionally, the treatment significantly improved in vitro protein digestibility, although it did not affect protein content (~20.0 %), amino acid content, amino acid score (0.3-0.5), or in vitro protein digestibility corrected amino acid score (in vitro PDCAAS) (0.2-0.4). Most importantly, heat treatment significantly enhanced the microbial quality by eliminating the microbial load in the raw Canary seed flour, ensuring the safety of the product. Our results suggest that hydrothermally treated canary seed flour has improved physicochemical and functional properties, making it a better substitute than its raw counterpart.

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.