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.

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.

Rice's yield, cooking, and sensory quality are primary considerations in selecting new breeding rice varieties, which are determined by the rice eating quality such as processing and flavor characteristics. Thus, in this study, to advance the breed of new superior japonica rice varieties, the differences in the rice quality, processing characteristics, and flavor characteristics between 12 newly-bred varieties (H2-36, H2-42, H2-53, H2-59, H2-63, H2-73, H2-74, H2-79, H2-81, H2-82, H2-89, and H2-91) and 1 commercial variety (Kenyu38) were analyzed. The results indicated that H2-42 has a reasonable length-to-width ratio (1.51), high rice yield, good color, reasonable amylose, protein content, excellent water existence index, accessible storage, and the highest taste value. Electronic nose results showed significant differences in aldehydes, ketones, and alcohols among 13 rice varieties. Aroma analysis results showed that H2-42 had the highest n-hexanal (14.63 µg/kg), (E,E)-2,4-nonadienal (37.24 µg/kg), nonanal (19.93 µg/kg), and decanal (4.81 µg/kg); those were important aroma components in cooked rice. The Pearson correlation analysis showed that hardness, springiness, cohesiveness, trough viscosity, peak time, and pasting temperature were the crucial factors that affected rice quality. According to partial least squares regression analysis, total color change, final viscosity, setback, (E)-2-heptenal, and 2-methyl-undecanol were the most important factors that distinguished the rice quality. In conclusion, H2-42 rice was better apparent quality, processing characteristics, and aroma compounds. Therefore, H2-42 has the potential for identification and promotion.

The purpose of this study was to physically process Hi-maize 260® granules and investigate the size reduction towards obtaining starch nano-particles, stable in aqueous suspensions. We developed a novel sequential three-step physical process consisting of hydrothermal gelatinization, nano-precipitation and ultrasonic treatment. Ultrasonication proved to be a key-step to dismantle the ununiform agglomerates nanoparticles produced by the nanoprecipitation of the hydrothermally gelatinized starch, furnishing uniform nanoparticles (170 nm). This was unveiled by complementary Dynamic Light Scattering (DLS) and electrophoretic mobility (Z-potential) studies, as well as fluorescence spectroscopy. Notably, this 3-step process reduced the size of the starch particles to nano dimensions without destroying their crystallographic structure, as shown by X-ray diffraction (XRD) and Small Angle X-ray Scattering (SAXS), or changing. their chemical integrity, as validated by Fourier transform infrared spectroscopy (FTIR) and Thermogravimetric Analysis (TGA) analyses. Finally, we evaluated the hydrophobicity of the isolated nanoparticles by employing the sessile drop method, witnessing an increment to the hydrophobicity as a result of size reduction. Collectively, we developed a handy protocol enroot to reduce the size of RS2 starch particles enabling its application in an array of meaningful real-world food applications.

Orange-fleshed sweet potato (OFSP) has attracted increasing attention due to its high carotenoid levels, which is beneficial to human health. However, the changes in the chemical composition of OFSP after cooking are not fully elucidated yet. In this study, the contents of starch, soluble sugar, carotenoids, volatile compounds, and metabolites of OFSP before and after cooking (steaming, boiling, and baking) were determined to evaluate the changes in its flavor and chemical composition. After cooking, the contents of starch decreased from 18.15% to 7%, and soluble sugar increased from 11.78% to 39.33%. The baked OFSP was the sweetest one due to the production of most sugars during baking. Additionally, the aroma of baked OFSP was the best due to the abundance of furans, aldehydes, ketones, and monoterpenes, including 6 volatiles produced by carotenoids. However, the steamed OFSP retained more carotenoids, while all carotenoids were reduced 7%-23% after cooking. Furthermore, 593 metabolites were identified in OFSP, of which 82.5% were well preserved after cooking. Overall, understanding of chemical profile changes of OFSP after cooking will provide a theoretical basis for broadening sweet potato processing and application.

The effects of maize starch (MS) and rice starch (RS) addition on rice noodle quality were investigated, aiming to develop high-quality noodles with both desirable textural properties and low starch digestibility. The results showed that the MS had more short branch chains and higher branch density when compared to RS, and the final viscosity and gel strength of rice paste decreased with its addition. The textural properties between rice noodles with less than 20% MS and without MS did not differ significantly, while the network structure of rice noodles with more MS was significantly weakened due to the steric hindrance of short branch chains. The addition of RS increased the texture quality of rice noodles. Moreover, their addition reduced the estimated glycemic index of rice noodles, because more starch promoted the arrangement of starch chains and formed ordered double helix. The MS with more short chains was conducive to the formation of double helix to reduce digestion rate, and the RS with more long chains formed stabler gel and crystal structures to reduce digestible starch content. Therefore, MS and RS addition had potential to produce rice noodles with high comprehensive quality, and MS content should be controlled below 20%.

The chestnut is widely cultivated fruit tree enriched with nutrients and has pleasant tasting fruit. The starch properties of kernels greatly influence the nutritional quality of chestnuts. Although various studies have examined the production and accumulation of starch in chestnuts, the transcription alteration linked with starch properties in the kernels has not yet been fully assessed. The present study was conducted to compare transcriptomic variation and starch profiling of three chestnut cultivars: “Garrone rosso” (eur), Castanea sativa Mill., native to Europe; “Dahongpao” (dhp) and “Jiandingyouli” (jdy), and Castanea mollissima Bl., native to China. The results revealed that “dhp” and “jdy” had higher amylose, amylopectin and total starch content than “eur”. Based on transcriptome data, we screened 63.17G clean bases, and detected numerous differentially expressed genes (DEGs) that were associated with starch and sucrose metabolism. Through the combined transcriptomic and starch profiling analysis showed that DEGs in “the starch and sucrose metabolism”, “bZIP transcriptional factors”, and “zinc finger protein” pathways were positively correlated with starch accumulation, genes encoding sucrose synthase (CMHBY215664 and CMHBY203813), USPase (CMHBY206855), and PGI (CMHBY200699) were found to participate in the biosynthesis, transport, and regulation of starch according to their expression patterns in chestnut kernels. Furthermore, genes encoding different transcription factors (ERF, bZIP, MYB, and WRKY) that potentially regulate the expression of genes involved in starch and sucrose metabolism were selected by coexpression analysis, which highlighted that most MYB and WRKY TF members were positively correlated with starch synthase (SS). qRT-PCR assay results of nine selected DEGs confirmed the accuracy of the RNA-Seq data. Our results provide insights into genetic resources for deciphering the molecular mechanisms of chestnut starch accumulation.

The study aims to investigate the structural properties of wheat starch (WS) after treatment with β-amylase at different hydrolysis times and to explore the physicochemical and storage properties of β-amylase hydrolyzed wheat starch (BA-WS). As the enzymatic digestion time increased, the degree of hydrolysis of the enzymatic starch samples increased, the amylose/amylopectin ratio decreased, the molecular weight decreased, and the relative content of low polymerization (DP) branched chains increased. The physicochemical properties of BA-WS changed as a result of the change in structural properties, such as the solubility index (SI) increased, while the swelling capacity (SP), storage modulus (G′), and loss modulus (G'') decreased. The differences between BA-WS stored for 1 day and 14 days were studied by low field NMR (LF-NMR) and confocal laser microscopy (CLSM), demonstrating that β-amylase increased the proportion of smaller particles, resulted in better water-holding gels due to the inhibition of water migration meanwhile.

Maize grain hardness influences storage pest resistance, a key characteristic valued by smallholder farmers. The structural changes in the endosperm determine grain hardness and are influenced by agronomic practices. The purpose of this study was to establish whether supply of calcium and magnesium based fertilizers can alter physicochemical properties of local and hybrid maize varieties and reduce the infestation by larger grain borer (Prostephanus truncatus (Coleoptera: Bostrichidae)) during storage. Two local and one hybrid maize varieties commonly grown by smallholder farmers in Malawi were cultivated under three fertilizer treatments (NPK (nitrogen, phosphorous, potassium), NPK plus gypsum, and NPK plus dolomite). After harvest, the grains were classified into flint and dent types, followed by P. truncatus infestation and determination of their physicochemical properties. The addition of gypsum and dolomite fertilizers led to higher levels of amylose, total zein and β-14 zein, traits associated with kernel hardness, compared to the application of NPK fertilizer. Moreover, local maize varieties showed higher resistance to P. truncatus infestation, hardness and biochemical properties associated with hardness (total zein, α-19 and β-14 zein, starch lysophosphatidylcholine, and non-starch free fatty acid) compared to hybrid variety. Our study suggests the potential for utilizing Ca and Mg nutrition in maize to improve kernel hardness, thus adoption of gypsum and dolomite by smallholder farmers may be beneficial against P. truncatus during storage.

Glycogen is a complex branched glucose polymer found in many tissues and acts as a blood-glucose buffer. In the liver, smaller β glycogen particles can bind into larger composite α particles. In mouse models of diabetes, these liver glycogen particles are molecularly fragile, breaking up into smaller particles in the presence of solvents such as dimethyl sulfoxide (DMSO). If this occurs in vivo, such a rapid enzymatic degradation of these smaller particles into glucose could exacerbate the poor blood-glucose control that is characteristic of the disease. High-amylose resistant starch (RS) can escape digestion in the small intestine and ferment in the large intestine, which elicits positive effects on glycemic response and type 2 diabetes. Here we postulate that RS would help attenuate diabetes-related liver glycogen fragility. Normal maize starch and two types of high-amylose starch were fed to diabetic and non-diabetic mice. Molecular size distributions and chain-length distributions of liver glycogen from both groups were characterized to test glycogen fragility before and after DMSO treatment. Consistent with the hypothesis that high blood glucose is associated with glycogen fragility, a high-amylose RS diet prevented the fragility of liver-glycogen α particles. The diets had no significant effect on the glycogen chain-length distributions.

The physicochemical properties and nutritional fractions of the starches isolated from nine Canadian-grown peas, including marrowfat, green, and yellow pea types, were studied and compared with six commercial starches, to explore the unique properties of these pea starches. These nine pea starches were found to have high apparent amylose content (marrowfat peas, 51.3%–51.6%; yellow peas, 50.6%-53.8%; and green peas, 49.9%-54.2%) and a higher tendency than most commercial starches to retrograde. Although their physicochemical properties were not drastically different, a green pea variety, Limerick, stood out for its significantly high apparent amylose content (54.2%) and also the highest resistant starch (RS) content after cooking (29.5%), the latter even comparable with a commercial high amylose corn starch (29.8%). Principal component analysis indicated that amylose content, amylose leaching, and Rapid Visco Analyzer (RVA) parameters at the cooling stage are significantly positively correlated to the starch nutritional fractions of cooked samples. Cluster analysis showed a clear pattern that the RS content in cooked starches increased with the increasing amylose content in these starch samples. In general, these pea starches were rich in slowly digestible starch and high in RS after cooking (>16%). This study highlighted the unique properties of these pea starches, including their high amylose content, and ease of gelatinization yet strong tendency toward retrogradation, which resulted in superior final pasting viscosity and high RS content; thus, these pea starches could be the best alternative to commercial high amylose starches, to address the latter's deficiencies in pasting properties when applying in gel-based low glycemic index (GI) foods.

In the production of starch, the drying process is a unit operation that can affect its functional properties; however, there is scarce information about the effect of dying process on modified starches such as OSA (2-octenyl-succinic anhydride) plantain starch. The modified starch was dried by convection (50°C) and spray drying (Ti = 150°C). The physicochemical, morphological, functional and digestibility characteristics of the samples were assessed. The gelatinized samples showed an increase in the SDS fraction related to starch modification, and the convection-dried sample showed an increase in the RS fraction. The drying process that presented a high nutraceutical starch fraction (SDS plus RS) was convection drying (58%). The drying process affects the functional properties of OSA-modified plantain starch due to a partial loss of organization within the granular structure of the modified starch, which is reflected in the spray-dried sample as high WAI (2.46 ± 0.04 g.100 g^-1), SP (2.48 ± 0.1 g.100 g^-1), low WSI (2.07 ± 0.1 g.100 g^-1), high pasting peak viscosity (0.39 Pas^-1) and low onset gelatinization temperature (66.0 ± 0.1°C) and gelatinization enthalpy (6.3 ± 0.1 J g⁻¹). The differences in the functional properties can be relevant to different industrial-technological applications.

This study aimed to investigate the proximate composition, mineral content, functional properties, molecular structure, in vitro starch digestibility, total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activity (DPPH, FRAP) of green banana flour (GBF) cultivars grown in South Africa. With proximate composition, Finger Rose and Pisang Awak had the highest protein (4.33 g/100 g) and fat (0.85 g/100 g) content, respectively. The highest ash content (3.50 g/100 g) occurred with both Grand Naine and FHIA-01 cultivars. Potassium and copper were the most abundant and least minerals, respectively. Pisang Awak cultivar had the highest water absorption capacity (67.11%), while Du Roi had the highest swelling power (0.83 g/g) at 90 °C. Scanning electron microscopy (SEM) images revealed that starch granules from all GBF cultivars were irregular in shape and they had dense surfaces with debris. All the GBF cultivars had similar diffraction patterns with prominent peaks from 15°-24° diffraction angles. The resistant starch (RS) and amylose content of the FHIA-01 cultivar indicates that the GBF has the potential to lower risks of type 2 diabetes and obesity. The highest TPC, TFC and antioxidant activity occurred with the Grande Naine cultivar. Based on their functional characteristics, the Grand Naine and FHIA-01 GBF cultivars could potentially be used as raw materials for bakery products as well as for the fortification of snacks.