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.

Seventeen pigmented maize cultivated in different locations of India were collected and evaluated for their nutritional, anti-nutritional and starch profile. A wide variation was observed in all the parameters evaluated. Protein and total dietary fiber content varied between 7.18 to 10.85 g/100g and 8.76 to 14.04 g/100g, respectively. Among the water-soluble vitamins, B₂ varied from 0.071 to 0.134; B_3, 1.50 to 2.79; B_5, 0.17 to 0.70 and B₆, 0.141 to 0.245 mg/100g; while total tocopherol and tocotrienol varied 1417 to 2246 µg/100g and 18.57 to 30.01 µg/100g, respectively. The resistant starch, total starch and amylose varied significantly and observed between 0.49 to 4.78 %, 61.33 to 69.65 % and 10.91 to 32.01 %, respectively. Among the minerals, Fe and Zn were observed between 1.51 to 5.01 and 2.25 to 5.51 mg/100g, respectively. Total polyunsaturated and total monounsaturated fatty acids were observed up to 45.72 and 55.54 %, respectively. Amongst the anti-nutrients, phytate was detected the lowest in Laal makki, whereas total and soluble oxalates were the lowest in Kashmiri red maize.

Water caltrop starch (WCS) isolated from the dehydrated water caltrop (DWCS) showed higher content of protein and ash as compared to starch isolated from fresh water caltrop (FWCS), leading to slightly lower starch purity. However, the pasting profiles of DWCS and FWCS are similar under a constant solid content of 4% (w/w). WCS/gum mixed systems contain 0.3%–0.9% gum generally showed higher pasting temperature, peak viscosity, and final viscosity than the starch alone system. The increase in peak and final viscosity during rapid-viscosity analysis was most pronounced for WCS/gum mixed systems with konjac glucomannan (KG), followed by guar gum (GG) and xanthan gum (XG). All WCS/gum mixed systems showed shear thinning and thixotropic characteristics. The extent of pseudoplasticity and shear stability, as evidenced by the smaller flow behavior index (n) and area of the hysteresis loop, was most pronounced for WCS/gum mixed system with XG, followed by mixed systems with GG and KG. Dynamic viscoelastic analysis revealed that the addition of gum increased both the storage and loss moduli of WCS, and lowered the frequency dependence of the loss factor significantly. However, the loss factor of WCS/gum mixed systems was generally higher than that of the starch alone system, implying the addition of gums modified the rheological characteristic of WCS to more viscous dominant behavior.

To investigate the effects of milling methods on the properties of rice flour and steamed rice cakes (SRCs), dry, semi-dry, and wet milling methods were compared. Damaged starch, particle size distribution, water hydration properties, gelatinization properties, gel strength, thermal properties, glass transition temperature, dynamic rheological properties of rice flour, sensory and textural properties of SRCs were evaluated. Semidry-milling rice flour (SF) had much less damaged starch and smaller particle size compared with dry-milling rice flour (DF). The pasting, hydration, and rheological properties of SF were similar to that of wet-milling rice flour (WF). Except for adhesion and appearance, the sensory and textural properties of SF SRCs were significantly better than that of DF SRCs, while comparable to WF SRCs. The results showed that semi-dry milling as an environmental, efficient, and convenient method could provide rice flour suitable to prepare SRCs. In view of sustainable and economic development, semi-dry milling could be a good alternative method in industrial production.

The rheological, thermal and textural properties of batter are critical for the eating and processing quality of soft cake products. Wheat starch molecular structures play an important role on these properties. However, the underlying mechanisms are not well understood. In this study, fluorophore-assisted carbohydrate electrophoresis and size-exclusion chromatography were used to measure amylopectin and amylose chain-length distribution. The obtained data were fitted with two different biosynthesis-based models, resulting in few biologically-meaningful parameters. For cake batter, the rheological, thermal and textural properties were measured by rheometer, differential scanning calorimetry and texture analyser. The length of amylose intermediate to long chains and amylopectin long chains was significantly positively correlated with the viscoelasticity of cake batter. The length of long amylose chains showed a negative correlation with the frequency value of crossover point between G′ and G″ curves. Moreover, different combinations of long amylopectin and intermediate-long amylose chains contributed to the formation of multi-endothermic gelatinization peaks. From flour-water system to flour-lipid-protein system, the main factors determining rheological and thermal properties changed from short amylopectin to long amylopectin and intermediate-long amylose chains. This study provides the first associations between starch molecular fine structure and functional properties of cake batter, which could help food industry breed and select suitable wheat varieties for improved batter quality.

This study explored the noodle-making performance of flour blends with different particle sizes and blending ratios of purple-colored wheat bran and their antioxidant properties. The bran particle size was reduced using an ultra-centrifugal mill equipped with 1, 0.5, and 0.2 mm sieves. The damaged starch and swelling capacity of the bran were analyzed. Quality of the flour-bran blends at different blending ratios was analyzed by solvent retention capacity (SRC). Noodles made from the blends and their corresponding antioxidant activities were examined. The damaged starch and swelling capacity of bran were higher for smaller particles than for larger particles. Water and sodium carbonate SRC values of blends increased as the bran particle size decreased. The smaller the bran particles incorporated in the cooked noodles, the greater firmness and springiness measured. The antioxidant activity of noodles made with blends reflected better embedding of the small particles of bran than the large particles into noodle sheets. Small bran particles significantly enhanced noodles’ quality and antioxidant activity at higher blending ratios than large bran particles. Particle size reduction of bran enhanced the noodle-making performance of flour blended with purple-colored wheat bran; this could increase the utilization of bran to produce noodles with health benefits.

Background and objectives: Low-pressure homogenization (30 MPa-3 passes) applied to long (LRF) and medium (MRF) rice grain flours was tested as physical method for improving gluten-free breads (GFB) without additives. Rice flours were blended with faba bean flour (FBF) in the ratio 2:1 (w:w). Findings: Low-pressure homogenization increased damaged starch content of rice flours and decreased the particle size distribution of blends, leading to higher volumes during batters' fermentation. Homogenization treatment improved the GFB texture profile, decreasing hardness and increasing cohesiveness and resilience. The crumb structure, particularly that of GFB from LRF:FBF blends, was greatly improved by the treatment, and better shape (lower width/height ratio) was obtained. No significant differences were found on the hardening rate of stored GFB, when using homogenized rice flours. Conclusions: In general, long rice homogenized flour revealed the greatest capacity to improve the GFB quality. Low-pressure homogenization of long or medium rice flour can be an adequate physical treatment to improve breadmaking properties of rice flours. Significance and novelty: The study confirms the suitability of low-pressure homogenized LRF and MRF blended with FBF as raw ingredient in GF breadmaking without additives.

A diet low in fermentable oligo-, di-, monosaccharides and polyols (FODMAPs) is a successful therapeutic approach to alleviate symptoms of irritable bowel syndrome. However, wheat, as a fructan accumulating grain, is a major source of FODMAPs. Baker's yeast degrades fructans during fermentation, yet conventional whole wheat bread is often still high in FODMAPs. In this study, 96 yeast isolates from different environments were screened regarding their capability to metabolise FODMAPs. Two promising isolates were identified: Lachancea fermentati FST 5.1 and Cyberlindnera fabianii NTCyb, and their potential to produce low FODMAP whole wheat bread was compared to baker's yeast (Saccharomyces cerevisiae). A comprehensive characterisation of the carbohydrate metabolism by the different yeasts was achieved via HPAEC-PAD analysis of flour, doughs, and breads. L. fermentati FST 5.1 fermented fructans and excess fructose much more efficiently than baker's yeast and resulted in bread low in FODMAPs (below all cutoff levels known to induce symptoms). In contrast, C. fabianii NTCyb was unable to ferment FODMAPs in the wheat-dough-matrix. Furthermore, the yeasts’ impact on the GC/MS-TOF profile of volatile aroma compounds, the sensory profile, the breads’ ultrastructure, and the technological quality was examined. While C. fabianii NTCyb bread had poor technological and sensory attributes, the quality characteristics (volume, crumb structure, texture, sensory, aroma) of L. fermentati FST 5.1 bread were comparable to the baker's yeast bread. Ultimately, this study identified Lachancea fermentati FST 5.1 as an alternative to baker's yeast to produce low FODMAP whole wheat bread while maintaining optimal bread quality and consumer acceptance.

Fresh nixtamalized maize dough (NMD) is commonly preferred by producers as raw material for the manufacture of a diversity of nixtamalized products. Based on the application, NMD may have different particle size distributions that may limit their analysis by common methods such as RVA. In the present study, we used the Mixolab to analyze fresh NMD produced with three degrees of cooking (undercooked, adequate cooked and overcooked) and milled to produce coarse, intermediate and fine doughs. Results were correlated with starch and tortilla features in order to evaluate the prediction of pregelatinization and starch damage occurring during processing, and with the quality of the final product. RVA was used for comparison purposes. Unlike RVA curves, Mixolab showed defined peak viscosities during heating independently of the milling degree of samples. Moreover, the Mixolab parameters showed strong correlations with the starch thermal properties, crystallinity, starch damage and lixiviated amylose. More correlations were obtained among Mixolab and RVA parameters in relationship with the attributes of tortillas. Results validated that the Mixolab is an efficient and rapid strategy to discern among different cooking degrees of fresh NMD independently of the particle size distribution, and may be useful to predict the quality of tortillas.

In this study, the effects of moisture changes on rice grain crack, volume and hardness during the semidry grinding process, as well as the damaged starch, microstructure, hydration, and pasting properties of rice flours prepared with different semidry grinding conditions were studied. Moisture changes of semidry grinding showed a “decrease-increase-decrease” pattern which represents hot-air treatment, tempering and drying process, respectively. With the moisture changes of semidry grinding, severe cracks occurred on the rice grains after hot-air treatment, and the hardness of the rice grains decreased rapidly in the first 15 min of tempering. For rice flours, the hot-air treatment and tempering were beneficial to reduce the content of damaged starch, and the tempering process had the greatest influence on the hydration and pasting properties of the rice flours among the three processes of semidry grinding. Moreover, the drying process had a positive effect on thermal paste stability and the resistance of retrogradation of the rice flours. These findings indicated that the “decrease-increase-decrease” pattern of moisture changes during the semidry grinding process affected the rice flour qualities, and could be used to guide the semidry grinding production of specific rice flours.

Modified rice flours were obtained by high-impact milling. A factorial design was performed in a planetary ball mill varying rotational speed (450-650 rpm) and milling time (10-40 min) while milling energy (0.3-4.3 kJ/g), particle size distribution (PSD) of rice flour, and changes in starch structure were recorded. The effect of rotational speed and time on milling energy was satisfactorily modeled by the Response Surface Methodology. Modified flours presented bimodal PSD unlike that of the control flour, which was monomodal with a lower size dispersion. A significant reduction of D[4,3] (mean diameter) was observed as the milling energy increased. However, the effect of milling energy on PSD was dependent on milling speed. Classical milling equations provided a satisfactory fit of energy-size records at low speed (450 rpm), but at higher speed, a poor adjustment was obtained due to the increasing relevance of heat dissipation. The empirical milling equation based on linear or exponential relationships between milling energy and size reduction ratio provided a good fit for experimental data. Significant correlations between milling energy and damaged starch, crystallinity, and gelatinization degree were found. The proposed mathematical models are a contribution to the milling process design for specific modifications of rice flour.

This study investigated the physicochemical properties of rice flour suspensions under ultrahigh hydrostatic pressure (UHP) treatment. Rice flour suspensions were subjected to 200, 400, and 600 MPa of pressure for 10 min, and heat treatment was used as a control. Proximate characteristics of different rice cultivar were analyzed to amylose, damage starch content, and particle size. Changes in physicochemical properties of rice flour suspensions according to UHP treatment were analyzed to microscopic structure, iodine reaction, α-amylase hydrolysis rate, and resistant starch content. Microscopic structural analyses showed that the structures of the rice flours were altered under both heat and 600 MPa treatment conditions. Water absorption rates were highest under heat treatment (467.53-554.85%), followed by 600 MPa treatment (269.55-334.57%). Iodine reaction values increased with increasing applied pressure. α-Amylase hydrolysis rates and resistant starch contents were highest under heat treatment and increased with increasing applied pressure. Based on these results, 600 MPa treatment of rice flour suspensions was shown to be comparable to heat treatment; as a result, the development of the new rice processing method with different physicochemical properties is expected from rice cultivars treated under UHP processing methods.

Three types of freezing methods, namely, spiral tunnel freezing method (SF), cryogenic refrigerator freezing method (RF) and liquid nitrogen spray freezing method (LF), were applied to frozen unfermented dough. The particle size distribution and SEM results showed freezing methods reduced the average particle size of starch granules and destroyed the surface microstructure, especially RF, and the damaged starch content and swelling power of starch after treatment increased. Gelatinization and pasting properties of starches changed to varying degrees, indicating freezing methods caused the internal rearrangement of starch molecules. This view could also be inferred from X-ray diffraction (XRD) and Fourier Transform infrared spectroscopy (FT-IR) data. The relative crystallinity (35.51%-38.56%) and the R_1047/1022 (0.562-0.590) were increased, compared with the control (32.44%, 0.559, respectively). Meanwhile, freezing treatment improved the digestibility of starch by promoting the combination of enzymes and starch, especially RF. Larger ice crystals formed by RF with slower freezing rate produced larger damage to starch structure, more likely to promote the binding with enzymes. LF with faster freezing rate had less effect on the starch composition than RF and SF with slower freezing rate. The data obtained clarified the influence of freezing methods on the structure and properties of starch in a yeast-free dough system, and enriched the knowledge regarding the effect of freezing technology on food components.

Our previous work reported that the brown rice flour prepared by low temperature impact mill possessed excellent physicochemical properties. The performance of brown rice flour in making gluten-free bread was further investigated. It was found that the starch crystal structure was destroyed and the damaged starch content increased as the particle size of brown rice flour decreased. The interaction between the starch and water in the model dough and the matrix structures among the endosperm masses were enhanced as the particle size decreased, making the gluten-free dough more viscoelastic. However, dough made with finer flour was too sticky, which limited the expansion of dough. Gluten-free bread prepared with medium-sized brown rice flour had favorable quality characterized by large specific volume, low hardness, numerous and homogeneous gas cells.

Recent research has shown that pulse‐derived ingredients present a technological alternative to cereals, higher protein and fibre content, and differentiated starch characteristics. In this work, the partial substitution of pulse flours with and without heat moisture treatment (HMT) was evaluated in a biscuit model. The digestion residues at 20 and 120 min that correspond to rapidly, slowly and resistant starch from the Englyst methodology were analysed by DSC, X‐Ray and ATR‐FTIR. The use of pulse flours in biscuits improved their thermal stability (ΔH = 3.01 and 4.99 J/g for control and Lentil + HMT), preserving a fraction of particularly ling glucans, that influenced the decreasing in the rapidly available starch from 55.26 to 24.11 % (Control and Faba bean + HMT), and enhanced its protein's digestibility from 75.26 to 87.43 % for the same sources. Among pulses, there were similarities regarding their resistance to enzymatic hydrolysis that may help select those with better organoleptic attributes.

Background and Objective: Limited data have been reported on the evaluation of physicochemical characteristics in millstreams (MS) obtained from large‐scale mills for hard red spring (HRS) wheat. Therefore, this research was designed to evaluate the MIAG‐Multomat mill that is a large‐scale experimental mill imitating the commercial flour mills. Findings: The MIAG‐Multomat mill yielded different trends across MS for ash and arabinoxylan. Specifically, reduction MS had lower ash content but higher arabinoxylan content than break MS. Moreover, arabinoxylan and other factors such as damaged starch content and coarse particle (over 600‐µm) percent had significant (p < .05) correlations with bread‐making traits including mixograph peak time, water absorption, and bread loaf volume, while ash had nonsignificant correlations with these quality traits. Conclusions: This research investigated the influence of physicochemical characteristics on bread‐making quality for the MIAG‐Multomat MS. Overall, the arabinoxylan, starch damage content, and coarse particle percent rather than flour ash content were identified as primary physicochemical components to influence variation of bread‐making traits for MIAG‐Multomat MS for HRS wheat. Significance and Novelty: The knowledge on composition of MS obtained in this research is valuable to optimize the functionality of flour blends, especially, in the long‐flow milling of HRS wheat.

In this study, the physicochemical characteristics of starch extracted from ten different cultivars of cassava roots, from different soils, were investigated. There are significant (p<0.05) variations in the proportion of starch damaged during extraction, even in samples of the same cultivar. Amylose content differs among cultivars and even within the same cultivar harvested in different soils (varying from 20.00 to 24.07%). According to the type of soil the starch samples showed distinct values for the crystallinity index. This indicates the need for the physicochemical characterization of starch samples to be carried out even when they originate from the same cultivar. The results obtained can be used as support tools for improvement of cassava genetics, optimizing the process of selection and maintenance of a genetic bank. The results, coupled with chemometric analyses (PCAs and clusters), allowed to distinguish cultivars according to their physicochemical and functional peculiarities, suggesting their potential to be used by industries and as food.