Chapter 1: Introduction
Chapter 2: Theory of the Analytical Procedure
Chapter 3: Kit Content & Reagent Preparation
Chapter 4: Weighing of Samples
Chapter 5: Starch Pretreatment
Chapter 6: Precipitation of Amylopectin with Con A & the Determination of Amylose
Chapter 7: Determination of Total Starch
Chapter 8: Determination of D-Glucose in Amylose and Total Starch Fractions
Chapter 9: Calculation of Amylose Content
100 assays per kit
Prices exclude VAT
Available for shipping
|Content:||100 assays per kit|
Short term stability: 2-8oC,
Long term stability: See individual component labels
|Stability:||> 2 years under recommended storage conditions|
|Limit of Detection:||Amylose 5-95% of total starch content|
|Total Assay Time:||~ 120 min|
|Application examples:||Cereal starches, flours, pure starches and foods.|
|Method recognition:||Novel method|
The Amylose/Amylopectin test kit is suitable for the measurement and analysis of amylose/amylopectin ratio and content in cereal starches and flours. Based on a Con A precipitation procedure.
See our full list of polysaccharide test kits.
- Very cost effective (cost per test)
- All reagents stable for > 12 months after preparation
- Only enzymatic kit available
- Accurate and reliable amylose / amylopectin ratio determination
- Simple format
- Standard included
McCleary, B. V., Charnock, S. J., Rossiter, P. C., O’Shea, M. F., Power, A. M. & Lloyd, R. M. (2006). Journal of the Science of Food and Agriculture, 86(11), 1648-1661.
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.Hide Abstract
McCleary, B. V., Gibson, T. S. & Mugford, D. C. (1997). Journal of AOAC International, 80, 571-579.
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%.Hide Abstract
Gibson, T. S., Solah, V. A. & McCleary, B. V. (1997). Journal of Cereal Science, 25(2), 111-119.
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.Hide Abstract
Variability in waxy (Wx) allele, in-vitro starch digestibility, glycemic response and textural behaviour of popular Northern Himalayan rice varieties.
Naseer, B., Naik, H. R., Hussain, S. Z., Shikari, A. B. & Noor, N. (2021). Scientific reports, 11(1), 1-10.
Eight commonly cultivated and consumed rice varieties of Northern Himalayan regions and a popular high amylose rice variety were characterized at Wx locus and evaluated for resistant starch (RS), in-vitro starch digestibility, predicted glycemic index (pGI), glycemic load (GL) and textural parameters. Cytosine and thymine repeats (CT)n at waxy locus (Wx) showed high association with apparent amylose content (AAC). Both pGI and GL varied substantially within the selected varieties. The pGI was relatively lower in high and intermediate amylose Indica varieties compared to low amylose Japonica ones. However, Koshikari despite being a low amylose variety showed relatively lower pGI and GL, due to its higher RS, dietary fiber, protein and fat content. It was thus presumed that in addition to AAC, RS and other grain components also affect the glycemic response. Inherent resistance to enzymatic hydrolysis was also found to be higher in firm textured and less sticky rice varieties. The genotypes-Lalat, Basmati-1509 and Koshikari, in view of their low to moderate pGI and relatively higher RS content, can be explored in future breeding programmes to develop rice varieties whose consumption will help to prevent hyper/hypo glycemic responses in Northern Himalayan regions, where daily staple diet is rice.Hide Abstract
Composition of Different Carbohydrate Fractions in Potatoes: Effect of Cooking and Cooling.
Raigond, P., Parmar, V., Thakur, A., Lal, M. K., Changan, S. S., Kumar, D., Dutt, S. & Singh, B. (2021). Starch‐Stärke, 2100015.
Effect of cooking methods (boiling, microwaving, pressure cooking) and storage conditions (-20, 4, 12°C) on resistant starch (RS), amylose, and sugars in the Indian cultivars, viz., Kufri Pukhraj and Kufri Chipsona-1 is investigated. Starch decreased significantly in Kufri Pukhraj and non-significantly in Kufri Chipsona 1 with a concomitant significant increase in reducing sugars and sucrose in cooked potatoes. Storage of microwaved tubers at 4°C for 48 h results in 4-6% reduction in starch content with 66-109% and 16-18% increase in reducing sugars and sucrose, respectively. Increase in RS content at -20, 4 and 12°C after 48 h is 14%, 21%, and 27% after microwaving, 12%, 25%, and 23% after boiling, and 13%, 15%, and 20%, respectively, after pressure cooking. Amylose showed high positive correlation with RS at 4°C (R = 0.756) and 12 h storage (R = 0.924). The study reveals that storage of microwaved potatoes at 12°C for 48 h increases the RS to a higher extent, therefore, these cooking and storage conditions may be used by potato consumers. Due to inverse relation of RS and amylose with glycemic index they can be used for indirect estimation of glycemic index.Hide Abstract
Effects of ultrasound-assisted enzymolysis on the physicochemical properties and structure of arrowhead-derived resistant starch.
Liang, Q., Chen, X., Ren, X., Yang, X., Raza, H. & Ma, H. (2021). LWT, 147, 111616.
The effects of ultrasound-assisted enzymolysis on the physicochemical properties and structure of arrowhead-derived type 3 resistant starch (RS3) were investigated. Compared with the traditional enzymolysis, ultrasonic treatment significantly (p < 0.05) increased the resistant starch yield by 34.46%. Enzymolysis reaction kinetics revealed that ultrasound-assisted enzymolysis remarkably increased the enzymolysis rate and amylose content. After ultrasound treatment, RS3 displayed higher solubility, swelling power, transparency, and water absorption capacity. The results of particle-size distribution, differential scanning calorimetry, X-ray diffraction, Fourier transform-infrared spectroscopy, and scanning electron microscopy analyses demonstrated that RS3 prepared by ultrasound-assisted enzymolysis exhibited a larger granule size, higher crystallinity, a more ordered and stable double helix structure with increased surface roughness compared to those of RS3 prepared by traditional enzymolysis. These findings provide a theoretical background for the preparation of RS3 using an ultrasound-assisted enzymatic method and will promote the development of ultrasound chemistry in starch science and technology.Hide Abstract
Tracking physical breakdown of rice-and wheat-based foods with varying structures during gastric digestion and its influence on gastric emptying in a growing pig model.
Nadia, J., Olenskyj, A. G., Stroebinger, N., Hodgkinson, S. M., Estevez, T. G., Subramanian, P., Singh, H., Singh, R. P. & Bornhorst, G. M. (2021). Food & function, 12(10), 4349-4372.
There is currently a limited understanding of the effect of food structure on physical breakdown and gastric emptying of solid starch-based foods during gastric digestion. Moisture uptake, pH, particle size, rheological, and textural properties of six solid starch-based diets from different sources (Durum wheat and high amylose white rice) and of different macrostructures (porridge, native grain, agglomerate/couscous, and noodle) were monitored during 240 min of gastric digestion in a growing pig model. Changes in the physical properties of the gastric digesta were attributed to the influence of gastric secretions and gastric emptying, which were both dependent on the buffering capacity and initial macrostructure of the diets. Differences between the proximal and distal stomach regions were found in the intragastric pH and texture of the gastric digesta. For example, rice couscous, which had the smallest particle size and highest buffering capacity among the rice-based diets, had the shortest gastric emptying half-time and no significant differences between proximal and distal stomach digesta physical properties. Additionally, a relationship between gastric breakdown rate, expressed as gastric softening half-time from texture analysis, and gastric emptying half-time of dry matter was also observed. These findings provide new insights into the breakdown processes of starch-based solid foods in the stomach, which can be beneficial for the development of food structures with controlled rates of breakdown and gastric emptying during digestion.Hide Abstract
Molecular structure, morphological, and physicochemical properties of highlands barley starch as affected by natural fermentation.
Waleed, A. A., Sajid, B. M., Mahdi, A. A., Al-Maqtari, Q. A., Abduqader, A. A., Ahmed, A., Fan, M., Li, Y., Qian, H., Jinxin, L. & Wang, L. (2021). Food Chemistry, 356, 129665.
The influence of natural fermentation on the highlands barley starch chemical structure, morphological, physicochemical, and thermal properties was studied. The findings showed that fermentation had no impact on starch fine structure but it decreased the molecular-weight from 2.26 to 1.04 × 108 g/mol in native highlands barley and after 72 h fermentation (FHB72) respectively. Also, it decreased amylopectin long-chains (B1 and B2) while increased short-chains. The intensity ratio of FT-IR at 995/1022 and 1047/1022 bands were found to be higher as the time of fermentation progressed, and the highest absorption-intensity at 3000-3600 cm−1 and higher swelling capacity were noticed in the starch of FHB72. During fermentation, pasting peak, final and setback viscosities were decreased. Microscopically, granules with more pores, damaged, cracked, and no growth rings were found in starches isolated after 48 h and 72 h of fermentation. This study indicated that fermentation up to 72 h is an effective method to modify highlands barley starch.Hide Abstract
Analysis of β-amylase gene (Amyβ) variation reveals allele associated with low enzyme activity and increased firmness in cooked sweetpotato (Ipomoea batatas) from East Africa.
Banda, L., Kyallo, M., Entfellner, J. B. D., Moyo, M., Swanckaert, J., Mwanga, R. O., Onyango, A., Magiri, E., Gemenet, D. C., Yao, N., Pelle, R. & Muzhingi, T. (2021). Journal of Agriculture and Food Research, 4, 100121.
β-amylase is a thermostable enzyme that hydrolyses starch during cooking of sweetpotato (Ipomoea batatas) storage roots, thereby influencing eating quality. Its activity is known to vary amongst genotypes but the genetic diversity of the beta-amylase gene (Amyβ) is not well studied. Amyβ has a highly conserved region between exon V and VI, forming part of the enzyme's active site. To determine the gene diversity, a 2.3 kb fragment, including the conserved region of the Amyβ gene was sequenced from 25 sweetpotato genotypes. The effect of sequence variation on gene expression, enzyme activity, and firmness in cooked roots was determined. Six genotypes carrying several SNPs within exon V, linked with an AT or ATGATA insertion in intron V were unique and clustered together. The genotypes also shared an A336E substitution in the amino acid sequence, eight residues upstream of a substrate-binding Thr344. The genotypes carrying this allele exhibited low gene expression and low enzyme activity. Enzyme activity was negatively correlated with firmness (R = -0.42) in cooked roots. This is the first report of such an allele, associated with low enzyme activity. These results suggest that genetic variation within the AmyB locus can be utilized to develop markers for firmness in sweetpotato breeding.Hide Abstract
Soft Durum Wheat as a Potential Ingredient for Direct Expanded Extruded Products.
Gu, B. J., Kerr, C. J., Morris, C. F. & Ganjyal, G. M. (2021). Journal of Cereal Science, 103184.
Soft durum wheat was extruded to assess the influence of independent parameters (moisture content, screw speed, and barrel temperature each) on system responses (back pressure, torque value, and specific mechanical energy input) and product responses (expansion ratio, unit density, water absorption index (WAI) and water solubility index (WSI)). The lowest barrel temperature (120 °C) and moisture content (16%) with the highest screw speed (250 rpm) resulted in the highest specific mechanical energy input, expansion ratio, and water solubility index in the extrudates. Among the three independent parameters evaluated, moisture content was the most influential factor on the system and product responses. Energy efficiency on solubility (EES) was defined, and the notable impact of moisture content on EES was observed. Extrudates made from soft durum wheat had a reasonable expansion ratio, proving its potential usage in snack and cereal products.Hide Abstract
The dynamic changes of glycogen molecular structure in Escherichia coli BL21 (DE3).
Wang, M., Liu, Q., Li, F., Tang, J., Xiong, X., Yang, Y., Ju, P., Wang, Z., Gilbert, R. G., Wang, L. & Wang, L. (2021). Carbohydrate Polymers, 117773.
Diurnal alteration of glycogen molecular structure has been identified in healthy mice. Recently, both fragile (disintegration in dimethyl sulfoxide) and stable (not disintegrating in DMSO) glycogen particles were found in Escherichia coli. However, how glycogen structure changes dynamically in E. coli is not clear. The question examined here is whether fragile, stable glycogen α particles occur in bacteria, following a similar pattern as in mice. In this study, we examine the dynamic changes of glycogen molecular structure over 24-h in E. coli BL21(DE3), using transmission electron microscopy, size exclusion chromatography and fluorophore-assisted carbohydrate electrophoresis at representative time points. It was found that glycogen structure was mainly fragile at the synthesis stage and largely stable during the degradation stage. qRT-PCR results indicated that balance of anabolic and catabolic gene expression levels in glycogen metabolism could be a key factor affecting the fragility of glycogen α particles in bacteria.Hide Abstract
Genetic and Environmental Variation in Starch Content, Starch Granule Distribution and Starch Polymer Molecular Characteristics of French Bread Wheat.
Rhazi, L., Méléard, B., Daaloul, O., Grignon, G., Branlard, G. & Aussenac, T. (2021). Foods, 10(2), 205.
This study investigates genetic and environmental variation in starch content and characteristics of 14 French bread cultivars. Understanding the impact of these factors on wheat quality is important for processors and especially bakers to maintain and meet the requirements of industrial specifications. Different traits were evaluated: starch content, distribution of starch granules, percentage of amylose and amylopectin and their molecular characteristics (weight-average molar mass, number-average molar mass, polydispersity and gyration radius). Genetic, environment and their interaction had significant effects on all parameters. The relative magnitude of variance attributed to growth conditions, for most traits, was substantially higher (21% to 95%) than that attributed to either genotype (2% to 73%) or G × E interaction (2% to 17%). The largest environmental contribution (95%) to total variance was found for starch dispersity. The highest genetic influence was found for the percentage of A-type starch granules. G × E interaction had relatively little influence (≈7%) on total phenotypic variance. All molecular characteristics were much more influenced by environment than the respective percentages of amylose and amylopectin were. This huge difference in variance between factors obviously revealed the importance of the effect of growing conditions on characteristics of cultivars.Hide Abstract
Enhancement of resistant starch content in modified rice flour using extrusion technology.
Gulzar, B., Hussain, S. Z., Naseer, B. & Naik, H. R. Cereal Chemistry, In Press.
Background and objectives: The present study was conducted with an aim to modify rice flour for enhancement of resistant starch content using extrusion technology. The effects of feed moisture, barrel temperature, and screw speed on resistant starch (RS), predicted glycemic index (pGI), glycemic load (GL), and instrumental color (L*, a*, and b* values) were investigated using response surface methodology. Findings: RS, pGI, GL, L*, a*, and b* varied between 4.91%-6.83%, 73.20-76.90, 48.0-53.04, 70.43-85.95, 6.92-10.32, and 15.09-30.81, respectively. Models obtained for these parameters were highly significant (p ≤ .0028). Significantly (p < .05) higher RS content (6.20%) and lower pGI and GL values (75.10 and 50, respectively) were recorded in modified rice flour (MRF) as compared to native rice flour (NRF). Lower values of pasting properties and higher thermal properties were recorded in MRF than NRF. Scanning electron micrographs showed continuous and dense network structures in MRF, whereas ungelatinized granules were evident in NRF. Conclusion: Extrusion processing caused significant changes in the digestibility of rice flour which increased the RS content and decreased the pGI in MRF. 30% moisture content, 140°C barrel temperature, and 70 rpm screw speed were found most feasible conditions to enhance RS content in MRF.Hide Abstract
A study on Australian sorghum grain fermentation performance and the changes in Zaopei major composition during solid-state fermentation.
Xu, X., Waters, D., Blanchard, C., & Tan, S. H. (2021). Journal of Cereal Science, 98, 103160.
Sorghum is an essential raw material traditionally used for baijiu production by solid-state fermentation (SSF). China imports Australian sorghum for animal feed and for baijiu production. Determination of the sorghum characteristics specific for baijiu production will enable target breeding for such purpose. This study used five Australian grain sorghum varieties and one Chinese variety for baijiu solid-state fermentation in order to determine the grain sorghum properties most suitable for ethanol production. Ethanol content was highly correlated with the grain total starch content (TS) (r = 0.675, p < 0.05), amylopectin (AP) content (r = 0.590, p < 0.05), C/N ratio (r = 0.837, p < 0.001) and crude protein content (r = −0.813, p < 0.01). This study concluded that the grain sorghum variety that produced high ethanol content, had higher TS, AP and C/N ratio but lower crude protein content. Changes in grain composition during fermentation was also studied. SSF involved the consumption of mainly amylopectin instead of amylose and non-resistant starch instead of resistant starch irrespective of sorghum variety. All fermented samples were found to have increased protein content.Hide Abstract
Influence of starch and protein molecular interactions on the in vitro digestion characteristics of biscuits partially substituted with pulse flours.
Chávez‐Murillo, C. E., Aceves‐Flores, M. S., Verástegui‐Quevedo, M. & de la Rosa‐Millán, J. International Journal of Food Science & Technology, In Press.
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.Hide Abstract
Effects of green wheat flour on textural properties, digestive and flavor characteristics of the noodles.
Zhang, K., Di, Z., Song, J., Guo, D., Xiao, Y. & Shen, R. Journal of Food Processing and Preservation, e15199.
The aim of this study was to compare the physicochemical and nutritional properties of three different varieties of green wheat kernel (ZhengMai7698, ZhongMai207, and BaiNong175), and then, evaluate the effect of whole grain green wheat flour on the noodle quality and develop a kind of the natural hypoglycemic noodle. ZhengMai7698, with high protein and fat contents, had a lower predicted blood glucose value. The effects of green wheat flour incorporation at different levels (0, 10, 20, and 30%) on the noodle‐making properties of wheat flour were investigated. The optimal cooking time, water absorption, and cooking loss of raw noodles increased, while the springiness and chewiness of cooked noodles decreased, with the addition of green wheat flour. From the study, it can be concluded that highly acceptable noodles can be prepared by incorporating the whole grain green wheat up to 30 g/100 g of wheat flour.Hide Abstract
Storage of biofortified maize in Purdue Improved Crop Storage (PICS) bags reduces disulfide linkage-driven decrease in porridge viscosity.
Nkhata, S. G., Liceaga, A. M., Rocheford, T., Hamaker, B. R. & Ferruzzi, M. G. (2021). LWT, 136, 110262.
Assessing rheological properties of biofortified maize through post-harvest storage is critical for its successful translation to consumer foods. Changes in flour rheology were assessed following post-harvest storage in Purdue Improved Crop Storage (PICS) of a white and two biofortified orange maize genotypes (OPVI and OPVII). Whole grains were stored in PICS bags with (PICS-oxy) or without (PICS-noxy) oxygen scavenger and compared to storage in traditional polypropylene woven bags. Flour pasting profiles were assessed over 8 months of storage. Initial porridge viscosities from biofortified maize were lower than from white maize. After 8 months, higher viscosities (p < 0.05) were observed in grain stored in PICS relative to woven bags. Sequestration of oxygen had a modest but significant effect (p < 0.05) on peak and final viscosities supporting the notion that oxidative processes mediate these effects. DTT treatment partially restored porridge viscosity suggesting disulfide linkages are involved in rheological changes during storage. Raman spectral analysis suggested storage-induced structural changes to the starch matrix. Overall, storage of biofortified maize in PICS alleviated disulfide linkage-driven decreases in viscosity of cooked porridge. With the potential to improve cooking quality of biofortified maize flours, application of PICS may be useful in translation of these grains to consumers.Hide Abstract
Physicochemical, thermal and rheological properties of isolated Argentina quinoa starch.
López-Fernández, M. P., Rodríguez, S. D., Favre, L. C., Busch, V. M. & del Pilar Buera, M. (2021). LWT, 135, 110113.
The aim of the present study was to evaluate the physicochemical, thermal and pasting properties of the starch of six quinoa genotypes native to the northwest of Argentina. The genotypes belonging to two genotype groups, highlands and dry valley, were grown in Jujuy, Argentina. Significant differences among genotypes were observed (P < 0.05) in amylose content, swelling power, water-binding capacity, thermal and pasting properties. In the different genotypes, the starch was characterized by a typical A-type X-ray diffraction pattern, with relative crystallinity ranging between 26.1 and 28.5%. Granule-bound starch synthase (GBSS), which is the single enzyme responsible for amylose biosynthesis, was also identified, with the 67- and 58-kDa quinoa polypeptides corresponding to the full-length and mature GBSS proteins. Studies of the pasting properties showed that the starch of the genotypes from the highlands had lower peak viscosity and lower breakdown parameter than that of the genotypes from the dry valleys. The results showed that the genotypic background and the environment influence the pasting curves. The novel findings discussed in this study constitute a starting point for research focusing on incorporating innovative technologies in the food and biomaterials industry.Hide Abstract
Granule morphological and structural variability of Thai certified glutinous rice starches in relation to thermal, pasting, and digestible properties.
Thitisaksakul, M., Sangwongchai, W., Mungmonsin, U., Promrit, P., Krusong, K., Wanichthanarak, K. & Tananuwong, K. (2020). Cereal Chemistry, In Press.
Background and objectives: Variation in composition and functionality of glutinous rice starch greatly affects their industrial application. This study examined the starch compositional, structural, and functional variability among five Thai glutinous rice cultivars, and the effect of molecular structure and composition on starch functionality was pinpointed. Findings: Amylose content, amylopectin chain‐length distribution (CLD), and relative crystallinity were not different among the cultivars (p ≤ .05), whereas RD14 possessed largest mean granule diameter. Conclusion temperature of gelatinization and peak viscosity (PV) were lowest in RD6 and RD10, respectively, while RD6, RD10, and RD14 had lower breakdown (BD) compared to others. Despite small variation within each parameter, multivariate analysis revealed the distinct characteristic of waxy donor, RD6, and RD10 compared to others. Proportion of amylopectin B1 chains and granule size showed negative correlation (r > 0.5) with PV and BD, respectively, whereas proportion of amylopectin B2 chains positively correlated (r > 0.5) with PV and final viscosity (FV). Conclusion: Amylopectin CLD and starch granule size were the key factors determining starch pasting properties among these waxy rice genotypes. Significance and novelty: Variations in composition, structure, and properties of Thai glutinous rice starches were observed, which could be adopted for a diverse array of end uses.Hide Abstract
Soaking induced discrepancies in oenological properties, flavor profiles, microbial community and sensory characteristic of Huangjiu (Chinese rice wine).
Yang, Y., Xia, Y., Hu, W., Tao, L., Liu, H., Xie, C., Bai, W. & Ai, L. (2020). LWT, 110575.
Soaking is a crucial process in adjusting initial fermentation acidity and achieving desired flavor quality of rice wines. Effects of soaking time on physicochemical characteristic of rice, flavor profiles, microbial community and sensory characteristic of Huangjiu were investigated. Soaking caused significantly changes in amylopectin content, and rice with high amylopectin content was conducive to produce esters and aldehydes during Hungjiu brewing. High-throughput sequencing showed that bacteria types were more abundant than fungi during brewing, suggesting that bacterial community might be primarily responsible for Huangjiu flavor. Differential analysis revealed that Weissella and Enterobacter contributed greatly to the accumulation of alcohols, esters and aldehydes during Huangjiu brewing, while Clostridium, Acinetobacter, Cyanobacteria, Zymomonas and Exiguobacterium were responsible for the rancidity. Based on spearman's correlation analysis, Lactococcus, Weissella, Pediococcus, Lactobacillus and Staphylococcus were the key microbial genera responsible for the flavor characteristic of Huangjiu. While favorable soaking caused an increased intensity in alcohol-aroma, full body and continuation of resultant Huangjiu, insufficient soaking led to a higher intensity of bitter taste. Summarily, soaking acidity ranged from 2 to 3 g/L was beneficial for preventing rancidity and improving the production of flavor compounds in Huangjiu.Hide Abstract