Amylose/Amylopectin 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 modified procedure for the determination of amylose in cereal starches and flours based on complex formation between the lectin concanavalin A (Con A) and amylopectin has been developed and characterised. The assay format is suitable for multi-sample analysis, allowing the analysis of up to 20 samples per day. In the procedure, the amylopectin in a solubilised, lipid-free starch sample is precipitated by reaction with Con A and removed by centrifugation. The amylose remaining in the supernatant is then determined after amylolytic hydrolysis to glucose and expressed as a proportion (%) of the glucose derived from amylolytic hydrolysis of the total starch in a separate aliquot of the solubilised sample (i.e. prior to Con A treatment). The Con A procedure correlates well (r>0•993) with existing Con A-based and iodine-based procedures and yields a linear standard curve for starch samples containing from ∼0 to ∼100% amylose. Advantages of this modified Con A procedure for amylose determination include its applicability to flour samples without the need for prior starch purification; it allows the simultaneous estimation of total starch and does not require a calibration curve. Repeated analyses of a set of samples yielded repeatability (within laboratory) relative standard deviations of <5% for pure starches and ∼10% for flours. A commercially available assay kit has been developed to facilitate the use of the Con A procedure in routine amylose determinations.

Static magnetic field (SMF), an innovative and eco-friendly technology, has attracted widespread attention in the field of modified starch physicochemical properties. This study aimed to investigate the effects of SMF treatment on the structural and digestive properties of germinated corn (GC) starch. In vitro digestibility examination of GC starch revealed that SMF treatment (30 mT, 2 h) led to a 12.76% reduction in the rapidly digestible starch (RDS), while slowly digestible starch (SDS) and resistant starch (RS) increased by 45.57% and 15.78%, respectively. Additionally, SMF treatment endowed GC starch with higher crystallinity and improved short-range order. Furthermore, the physicochemical property analysis indicated that SMF treatment decreased the swelling power, solubility, and oil absorption of GC starch by 31.62%, 51.19%, and 25.92%, respectively. These findings support the development of low-glycemic index (GI) foods and demonstrate a potential to modify GC starch structure and reduce starch digestibility through a green pathway.

Individuals affected by celiac disease or non-celiac gluten sensitivity disease need to adhere to a lifelong gluten-free (GF) diet. However, most of the GF products available in the market are low in nutritional qualities, as they are mainly starch-based. The use of wholegrain cereals in GF bread is therefore a promising strategy to improve its nutritional quality, in particular when using pigmented varieties. Pigmented rice is high in anthocyanins and phenolic acids that can help preventing chronic diseases. This study investigated the applicability of wholegrain pigmented rice (brown, red, black) in developing GF bread using ohmic and conventional heating processes. The addition of pigmented rice to GF breads resulted in higher specific bread volume, lower crumb firmness and relative elasticity, while porosity was increased, although with less unform pore size, compared to control bread from white (polished) rice. Wholegrain pigmented rice addition resulted in significantly higher amounts of total dietary fiber, total phenolic content, and antioxidant activities of GF breads. Overall, this study demonstrated that wholegrain pigmented rice flours have the potential to improve the physical and nutritional values of GF breads.

Starch–lipid complexes have attracted widespread attention owing to high anti-digestibility and thermal stability. However, methods to increase the content of starch-lipid complexes are limited. Therefore, this study aims to investigate the effect of atmospheric cold plasma (ACP) treatment for different times (0, 1, 3, 5, and 7 min) on the formation and structure of complexes between maize starch (MS) and lauric acid (LA). The results showed that the amylose content of MS increased from 18.44% to 31.01% after ACP treatment. Moreover, structural characterization of complexes revealed that short-term ACP treatment (1 min) favored the formation of MS–LA complexes, resulting in a better V-type crystalline structure (14.90%) and short-range ordered structure (0.793) with higher thermal stability (4.47 J/g) and no obvious morphological differences. In addition, the resistant starch content of MS-LA complexes increased from 30% to 33% in MS treated with ACP for 1 min. This may be because the active substances in ACP depolymerized starch, destroyed α-1,6 glycosidic bonds, broke branch chains, and increased amylose content, which promoted the formation of complexes to a certain extent. This study proposes a method to promote the formation of starch-lipid complexes, broadening potential application of complexes in low-GI food, stabilizer, and microcapsule carrier.

Background and Objectives: Effects of the physicochemical properties of buckwheat flour (BKF), quinoa flour (QF), proso millet flour (PMF), and whole wheat flour (WWF) were evaluated in a pancake product made with unbleached fine wheat pastry flour (FWF). Pancakes were formulated with 25%, 50%, 75%, and 100% (w/w) substitution levels. FWF was used as the control. Findings: The flours varied in composition, affecting their functional properties. BKF was characterized by high total dietary fiber (TDF), FWF had the highest starch content, WWF had the highest protein content, and PMF had the highest peak and onset temperature. The influential functional properties on pancake quality were the content of TDF and insoluble dietary fiber, as well as the water and oil holding capacity. Due to the rapid cooking time in pancakes, the PMF starch did not gelatinize adequately, likely due to the amylose content or shape and size of the starch, resulting in a low-hardness pancake without a continuous matrix. When a pancake was prepared with partial pregelatinized PMF, the pancake had a continuous matrix. Conclusion: BK, QF, and WWF can be incorporated into pancake formulations without flour modification. PMF must be modified before usage in a pancake application to ensure that a continuous matrix is formed.

To uncover the variation patterns of the nutritional components in sweetpotato storage roots during long-term storage comprehensively, the general nutrients, phytochemicals, and starch properties of nine sweetpotato varieties with different flesh colors were quantified and analyzed by chemical and physical techniques. During the storage, the starch content decreased firstly and then increased, with sugar content the opposite. The crude protein content and the total dietary fiber content both increased continuously. The β-carotene content decreased or kept constant, while the anthocyanin content showed different variation patterns in the three purple-fleshed varieties. The four types of polyphenols and two types of flavonoids showed no obvious content changes during the storage. The amylose contents of all varieties showed various patterns, while the crystallinity was C-type. The proportion of small-sized starch granules reduced, and the combined proportion of medium-sized and large-sized granules increased. New correlations among the nutritional parameters for each variety were revealed for the first time. Principal component analysis indicated that the orange-fleshed varieties were distinguished from other varieties. Finally, the most storage-resistant variety ZZ3 and the suitable variety for each quality trait was selected. This study provides not only theoretical basis for comprehensive understanding of the nutrient's variations in sweetpotato storage roots during long-term storage, but also guidelines for evaluation of nutritional quality of sweetpotato roots during storage and improvement of storage methods.

In this study, four varieties of glutinous rice were screened out of 18 varieties as representative model inks. Gel prepared using variety WN9612 of high amylose content displayed high viscosity and large overall print deviation (OPD = 17.4 ± 0.4 %) due to difficulties in extrusion. Printed item by variety 19415 of medium amylose content showed good printability (OPD = 4.4 ± 0.4 %) and highest hardness (197.5 ± 7.3 N). Similarly good printability was demonstrated by variety 19416 (OPD = 4.1 ± 0.2 %) containing low amylose content but abundant protein and bound-water. Variety WN9446 lacking protein and moisture created item with fluid structure, lowest gel strength (738.5 ± 20.9 Pa) and standing ability. Therefore, low to medium amylose content rendered suitable viscosity, extrudability and printability of rice gel while non-starchy components predominated water mobility and texture of 3D printed items. This study for the first time establishes theoretical groundwork of selecting glutinous rice varieties with appropriate chemical composition as all-natural materials in 3D printing and food customization.

The potential for improving sweetpotato quality remains underutilized due to a lack of comprehensive quality data on germplasm resources. This study evaluated 296 core germplasms, revealing significant phenotypic diversity across 24 quality traits in both stem tips and roots. Landraces had higher sugar content in roots, while wild relatives showed increased total flavonoid and phenol contents. Accessions with red-orange flesh were rich in sugars and carotenoids, whereas those with purple flesh had higher dry matter, flavonoids, and phenols. The accessions were classified into three clusters: high sugars and carotenoids, high phenolic compounds, and high starch. A comprehensive quality scoring model identified SP286 and SP192 as superior for stem tips and roots, respectively. Near-infrared spectroscopy, combined with a random forest algorithm, enabled rapid screening of superior germplasm, achieving prediction accuracies of 97% for stem tips and 98% for roots. These findings offer valuable resources and high-throughput models for enhancing sweetpotato quality.

Sweet potato is a rich source of resistant starch, fibre, vitamins and minerals, which is associated with healthy benefits. In this study, the effects of high hydrostatic pressure (HHP) treatment at 200–600 MPa on the digestibility of sweet potato flour (SPF) through starch composition analysis, in vitro digestion assays, and glycemic index (GI) and response in diabetic mice. Changes in the morphology of starch granules post-treatment were observed using an scanning electron microscope (SEM). Treatments at 400 and 600 MPa increased amylose in sweet potato starch and significantly increased the proportion of slowly digestible starch (SDS), as indicated by in vitro digestion assays. Resistant starch content decreased, with no significant change in rapidly digestible starch. Peak glucose levels in diabetic mice post-consuming SPF treated at 400 and 600 MPa were 476 and 514, respectively, significantly lower than 608 in the control group. The area under the curve (AUC) of 400 MPa treated-SPF is 14% lower than control SPF. The GI of SPF in the control group was 78.6, reducing to 66.2 and 68.3 post-HHP treatment at 400 and 600 MPa, respectively, with no significant difference in the 200 MPa group from that of the control group. SEM observations showed that damage to starch granules increased with increasing processing pressure. HHP caused the starch granules to gelatinize and recoagulate, forming an irregular shape. The HHP treatment changed the composition of SPF, significantly increasing SDS content and it stabilized postprandial blood glucose levels and reduced GI, rendering it a potential method to develop processed products of sweet potatoes with a low GI, providing a novel technical option for developing health-promoting products.

This study examined the impacts of four wheat cultivars and enzyme supplementation on growth performance, nutrient digestibility, and ileal microbiota composition in broiler chickens. Six hundred forty-eight male broilers (1-day-old, Ross 308) were studied in a completely randomized design factorial 4 × 2 along with control (9 treatments) with 6 replications (12 birds per pen). The Diets consisted of the four varieties of wheat (Sardari, Azar2, Sirvan, and Pishgam) with and without enzyme supplementation, alongside a corn-based control diet. All diets were iso-caloric and iso-nitrogenous. Daily weight gain (DWG) and feed conversion ratio (FCR) were not significantly affected by the dietary treatments. Broilers fed the corn-based diet displayed higher feed intake (FI) than those fed diets containing different wheat cultivars. Enzyme supplementation in wheat-based diets did not impact broiler growth performance. There was an interaction between enzyme and wheat type for protein, fat, calcium, and phosphorus digestibility. Ileal microbiota analysis revealed no significant changes in Lactobacillus and Escherichia coli populations across treatments. Conversely, Enterococcus and Bifidobacteria populations exhibited significant differences, with the Sirvan cultivar diet promoting the highest bacterial counts. It was concluded that different wheat cultivars could affect growth performance, nutrient digestibility, and ileum microbiota, and the beneficial effect of supplemental enzymes was only evident in certain variables and depended on the specific wheat variety.

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.

Investigations on the pyrolysis and potential flame retardancy imparted by solvent-free and semi-dry phosphorylation of different starches using sodium orthophosphates were conducted. The samples – low-substituted starch phosphates (SP) with degrees of substitution DS_P < 0.5 - were subjected to differential scanning calorimetry, thermogravimetry coupled with evolved gas analysis and pyrolysis – gas chromatography – mass spectrometry. The data obtained as well as features of charring residues examined using microscopic and spectroscopic methods were related to structural aspects of SP – analysed by means of various spectroscopic techniques - and compared with those of native starches. It was found that charring and polyphosphate formation and the thermal resistance of the solid SP residues increased significantly if the DS_P was at least 0.1. Accordingly, the exothermal decomposition, the temperature-induced loss of mass and the decomposition rates of SP decreased distinctly compared to native starch. The activation temperatures of SP and the formation of low-molecular pyrolysis products including aliphatic, cyclic, and aromatic aldehydes and ketones as well as anhydrosugars decreased markedly, even at DS_P < 0.1. The results confirm the potential flame-retardancy of SP achieved by flame-inhibiting effects, despite low phosphorylation degrees, in both the gas and condensed phases.

In a 21-d study, 480 Cobb 500 (off-sex) male broiler chicks were used to investigate the effects of feeding different sources and levels of resistant starches (RS) on growth performance, nutrient and energy utilization, and intestinal health in broiler chickens. The birds were allocated to 10 dietary treatments in a 3 × 3 + 1 factorial arrangement. The factors were 3 RS-sources (RSS): banana starch (BS), raw potato starch (RPS), and high-amylose corn starch (HCS); each at 3 levels (RSL) 25, 50, or 100 g/kg plus a corn-soybean meal control diet. Birds and feed were weighed on d 0, 8, and 21. On d 21, samples of jejunal tissue and digesta were collected for chemical analysis. Data were analyzed using the mixed model procedure of JMP with factor levels nested with the control. In the 0 to 21 phase, the birds fed the RPS diets had higher (P = 0.011) FI than those fed HCS or control diets, and FCR was greater (P = 0.030) in birds that received BS diets than in other diets. RSS × RSL was significant (P < 0.05) for total tract nutrient retention, AME, and AMEn on d 21. The starch digestibility was higher (P < 0.001) in birds that received the control diet than in RS diets, and decreased as RS levels increased, except for HCS. The apparent metabolizable energy (AME) and nitrogen-corrected AME (AMEn) were higher (P < 0.001) in birds fed 100 g/kg HCS diet, with both decreasing with increasing levels of BS and RPS, except for HCS. Relative ileal oligosaccharides profile showed significant (P < 0.05) RSS × RSL with a higher relative abundance of Hex(3) (P = 0.01) and Pent(3) (P = 0.001) in HCS diets. In conclusion, RS may influence gut health and growth performance in broiler chickens through modulation of cecal SCFA and nutrient digestion, but these depend largely on the botanical origin and concentrations of individual RS.