Raw Rice Starch Research Articles

Extraction process, physicochemical properties, and digestive performance of red yeast rice starch.

In the present study, taking red yeast rice (RYR) as the raw material, the optimum extraction process of RYR starch was investigated through a single-factor experiment and the Box-Behnken design: The liquid-to-solid ratio was 5mL/g, the concentration of sodium hydroxide solution was 0.075mol/L, and the extraction time was 3.1h. Under these extraction conditions, the extraction rate of starch reached 90.077%. To explore the influence of solid-state fermentation on RYR starch, three different fermentation stages of RYR starch, raw rice starch, semi-gelatinized rice starch, and RYR starch were used as test materials to determine the changes in the physicochemical properties and glycemic index (GI) values of RYR starch during solid-state fermentation. The results showed that with the advancement of the RYR solid-state fermentation process, the starch particle size gradually increased, the light transmittance gradually decreased, and the solubility and swelling power significantly increased. In addition, the amylose content of starch gradually increased, whereas the amylopectin content gradually decreased; the content of fast digestible starch and slow digestible starch decreased, whereas the content of resistant starch increased. In parallel, during solid-state fermentation, the hydrolysis index significantly decreased, and the GI values also decreased. In summary, solid-state fermentation reduced the digestibility of RYR starch. These results provide a theoretical basis for the structural and physicochemical properties of RYR starch and lay a foundation for its subsequent application and expansion of RYR starch.

Morphological, physicochemical, and functional properties of 15 different dietary carbohydrate sources in Sri Lanka

AbstractBackgroundCarbohydrate is the primary source of energy in the human diet and plays an important role in a healthy diet. In this study, 15 different carbohydrate sources (white raw rice, red raw rice, white basmati rice, red basmati rice, wheat, atta flour, soy, black gram, corn, finger millet, water lily seeds, kithul, chickpea, oats, and palmyra sprouts) in Sri Lanka were investigated for their physicochemical and functional properties.ResultsThe shape of the extracted starch granules varied according to the source, and the amylose content ranged from 17.22% to 36.12%. Kithul and black gram showed the highest water swelling capacity and water absorption index, respectively. Flour of white raw rice and finger millet showed significantly higher (p < 0.05) freeze–thaw stability than other sources. Flour of Soy, black gram, and chickpea showed significantly higher (p < 0.05) dietary fiber content and potassium content than other samples. Water lily seeds showed remarkable in vitro prebiotic activity from the studied carbohydrate sources.ConclusionThe study indicates the potential utilization of raw white rice, palmyra, and finger millet starch in the food processing industry as alternatives to conventional starch sources. Furthermore, the flour from water lily seeds, white basmati rice, soy, and black gram has the potential for use in functional food preparation, offering a wide range of health benefits.

Effect of starch retrogradation on molecular dynamics of cooked rice by quasi-elastic neutron scattering

Starch retrogradation can be evaluated using X-ray diffraction (XRD) techniques, which can estimate the crystallinity of starch. It is well known that the crystallinity is reflected in the mechanical properties of foods and materials. Crystallinity should be also related to the structural dynamics of starch, but there are no reports on the relationship between these properties. In this study, we used quasi-elastic neutron scattering (QENS) to investigate changes in the molecular dynamics of cooked rice starch during retrogradation. The width of the measured QENS narrowed with retrogradation. The elastic incoherent structure factor (EISF) increased, which indicated that the molecular dynamics are spatially suppressed upon retrogradation. However, the width of the quasi-elastic scattering component was independent of retrogradation in the measured Q-range. Analysis of EISF with a bimodal continuous diffusion model, where low and high mobilities are assumed to correspond to crystalline and amorphous phases, respectively, showed that the fraction of the low-mobility component increases with retrogradation. The suppression of the molecular dynamics during retrogradation was correlated with the crystallinity evaluated by XRD. The molecular dynamics of the crystalline region that appeared after gelatinization and retrogradation were different from that of raw rice starch. These results suggest that molecular dynamics reflect the state of retrogradation and can be used to monitor retrogradation of starch in foods.

Preparation of Resistant Rice Starch and Processing Technology Optimization

AbstractResistant starch has been attracting increasing attention due to its health benefits. Rice, is composed of 80% starch and represents a potential resource for resistant starch production with low. Using rice starch as a raw material displayed no noticeable adverse effects on the taste and texture of applied food. This study aimed to produce an effective method for improving resistant rice starch. A commercial rice ground to prepare the rice starch, after which the protein is removed using NaOH. The autoclave‐cooling processing technology is optimized via single‐factor experiments and the Box‐Behnken response surface methodology design. The results indicated that the highest yield of resistant starch reached 9.78%, about 10 times the level in raw rice starch. The optimal conditions included a starch slurry concentration of 18%, and autoclave gelatinization at 115 °C for 80 min, followed by natural cooling to room temperature.

AmyZ1: a novel \u03b1-amylase from marine bacterium Pontibacillus sp. ZY with high activity toward raw starches

BackgroundStarch is an inexpensive and renewable raw material for numerous industrial applications. However, most starch-based products are not cost-efficient due to high-energy input needed in traditional enzymatic starch conversion processes. Therefore, α-amylase with high efficiency to directly hydrolyze high concentration raw starches at a relatively lower temperature will have a profound impact on the efficient application of starch.ResultsA novel raw starch digesting α-amylase (named AmyZ1) was screened and cloned from a deep-sea bacterium Pontibacillus sp. ZY. Phylogenetic analysis showed that AmyZ1 was a member of subfamily 5 of glycoside hydrolase family 13. When expressed in Escherichia coli, the recombinant AmyZ1 showed high activity at pH 6.0–7.5 and 25–50 °C. Its optimal pH and temperature were 7.0 and 35 °C, respectively. Similar to most α-amylases, AmyZ1 activity was enhanced (2.4-fold) by 1.0 mM Ca2+. Its half-life time at 35 °C was also extended from about 10 min to 100 min. In comparison, AmyZ1 showed a broad substrate specificity toward raw starches, including those derived from rice, corn, and wheat. The specific activity of AmyZ1 towards raw rice starch was 12,621 ± 196 U/mg, much higher than other reported raw starch hydrolases. When used in raw starch hydrolyzing process, AmyZ1 hydrolyzed 52%, 47% and 38% of 30% (w/v) rice, corn, and wheat starch after 4 h incubation. It can also hydrolyze marine raw starch derived from Chlorella pyrenoidosa, resulting in 50.9 mg/g DW (dry weight of the biomass) of reducing sugars after 4 h incubation at 35 °C. Furthermore, when hydrolyzing raw corn starch using the combination of AmyZ1 and commercial glucoamylase, the hydrolysis rate reached 75% after 4.5 h reaction, notably higher than that obtained in existing starch-processing industries.ConclusionsAs a novel raw starch-digesting α-amylase with high specific activity, AmyZ1 efficiently hydrolyzed raw starches derived from both terrestrial and marine environments at near ambient temperature, suggesting its application potential in starch-based industrial processes.

Extensive hydrolysis of raw rice starch by a chimeric α-amylase engineered with α-amylase (AmyP) and a starch-binding domain from Cryptococcus sp. S-2.

Recombinant chimeric α-amylase (AmyP-Cr) was constructed by a catalytic core of α-amylase (AmyP) from a marine metagenomic library and a starch-binding domain (SBDCr) of α-amylase from Cryptococcus sp. S-2. The molecular fusion did not alter optimum pH, optimum temperature, hydrolysis products, and an ability of preferential and rapid degradation towards raw rice starch, but catalytic efficiency and thermostability were remarkably improved compared with those of the wild-type AmyP. AmyP-Cr achieved the final hydrolysis degree of 61.7 ± 1.2% for 10% raw rice starch and 47.3 ± 0.8% for 15% raw rice starch after 4h at 40°C with 1.0U per mg of raw starch. The catalytic efficiency was very high, with 3.6-4.0 times higher than that of AmyP. The enhanced catalytic efficiency was attributed to the better thermostability and the higher adsorption and disruption to raw rice starch caused by SBDCr. The properties of AmyP-Cr open a new way in terms of a new design of raw rice starch processing.

Identification and characterization of a novel raw-starch-degrading α-amylase (AmyASS) from the marine fish pathogen Aeromonas salmonicida ssp. salmonicida

A glycoside hydrolase family protein, designated AmyASS, from the marine fish pathogen Aeromonas salmonicida ssp. salmonicida A449 was expressed in Escherichia coli as inclusion bodies, which was renatured by a simple stepwise dialysis. AmyASS has more than 50% identity with many putative glycosidases. Based on the mode of hydrolytic action and the type of substrates, AmyASS was clearly defined as a saccharifying-type α-amylase, which is the third extracellular α-amylase of A. salmonicida ssp. salmonicida. AmyASS showed a raw starch digesting ability, and the specific activity toward raw rice starch (23.5±1.6Umg−1) was much higher than that toward raw wheat starch and raw mung starch. The catalytic region of AmyASS has 50% identity with the raw starch-degrading α-amylase AmyP, whereas AmyASS does not possess a starch-binding domain (SBD). AmyASS was optimally active at pH 6.0 and 40°C toward soluble starch and at pH 7.0 and 40°C toward raw starch. The enzyme exhibited stability under acidic (pH 6.0) conditions, while the activity decreased rapidly under neutral (pH 7.0) conditions. The AmyASS activity was stimulated by Ca2+, Co2+ and Cu2+.

A starch‐binding domain identified in α‐amylase (AmyP) represents a new family of carbohydrate‐binding modules that contribute to enzymatic hydrolysis of soluble starch

A novel starch-binding domain (SBD) that represents a new carbohydrate-binding module family (CBM69) was identified in the α-amylase (AmyP) of the recently established alpha-amylase subfamily GH13_37. The SBD and its homologues come mostly from marine bacteria, and phylogenetic analysis indicates that they are closely related to the CBM20 and CBM48 families. The SBD exhibited a binding preference toward raw rice starch, but the truncated mutant (AmyPΔSBD) still retained similar substrate preference. Kinetic analyses revealed that the SBD plays an important role in soluble starch hydrolysis because different catalytic efficiencies have been observed in AmyP and the AmyPΔSBD.

Purification, crystallization and preliminary crystallographic analysis of the marine α-amylase AmyP.

AmyP is a raw-starch-degrading α-amylase newly identified from a marine metagenome library. It shares low sequence similarity with characterized glycoside hydrolases and was classified into a new subfamily of GH13. In particular, it showed preferential degradation to raw rice starch. Full-length AmyP was cloned and overexpressed in Escherichia coli, then purified and crystallized in the presence of its substrate analogue β-cyclodextrin. X-ray diffraction data were collected to a resolution of 2.1 Å. The crystal belonged to space group P2₁2₁2, with unit-cell parameters a=129.824, b=215.534, c=79.699 Å, α=β=γ=90°, and was estimated to contain two molecules in one asymmetric unit.

Prececal digestibility of various sources of starch in minipigs with or without experimentally induced exocrine pancreatic insufficiency

Low prececal digestibility of starch leads to a higher starch flux into the hindgut, causing a forced microbial fermentation, energy losses, and meteorism. For exocrine pancreatic insufficiency (EPI), lack of pancreatic amylase can be compensated mostly by hindgut fermentation of starch. Even in pigs with complete loss of pancreatic secretion, starch digestibility over the entire tract is reaching levels of controls. To optimize diets for human patients with EPI, the proportion of starch that is digested by the ileum is important. Minipigs were fitted with an ileocecal reentrant fistula (n = 8) to determine prececal digestibility of starch. In 5 minipigs the pancreatic duct was ligated (PL) to induce EPI; 3 minipigs served as controls (Con). Various starch sources were tested in a 1-d screening test; therefore, disappearance rate (DR) instead of digestibility was used. Test meals consisted of 169 g DM of a basal diet plus 67.5 g DM of the starch (without thermal treatment; purified; starch content of 89 to 94.5%) and Cr(2)O(3). The test meal contained (% of DM) starch, 67; crude fat, 1.69; CP, 15; crude fiber, 2.0; and Cr(2)O(3), 0.25. In PL, prececal DR of starch was lower than in Con (P < 0.05) for all starch sources. In Con, prececal DR of starch was almost complete (>90%) but was lower (P < 0.05) for potato (Solanum tuberosum) starch (75.4%). In PL, prececal DR of starch was higher (P < 0.05) for wheat (Triticum aestivum) starch (61.2%) than corn (Zea mays) starch (43.0%) and rice (Oryza sativa) starch (29.2%) and intermediate for potato and field pea (Pisum sativum) starch. For patients with EPI, wheat starch seems favorable due to the higher prececal digestibility whereas raw corn and rice starch should be avoided.

Preferential and rapid degradation of raw rice starch by an α-amylase of glycoside hydrolase subfamily GH13_37

The α-amylase (AmyP) from a marine metagenomic library belongs to the recently classified glycoside hydrolase subfamily GH13_37. The degradation abilities of AmyP on a broad range of raw starch granules were examined at 40 °C and pH 7.5. It was found that AmyP is a raw starch-degrading enzyme, exhibiting a unique and remarkable ability to preferentially and very rapidly digest raw rice starch. The specific activity of raw rice starch was reached 118.5 ± 0.6 Umg(-1), which was much higher than that of other raw starches. The final hydrolysis degrees were obtained in 4 h for 1 % raw rice starch and 1 h for 8 % concentration, indicating a very rapid speed of hydrolysis. The presence of a starch residue resistant was the main limiting factor for complete hydrolysis, although end product inhibition also existed, especially at high starch concentrations. AmyP randomly attacks unique or susceptible sites on raw rice starch granules, and releases glucose, maltose, and maltotriose as end products. This is the first biochemical characterization of the raw starch-degrading ability of an α-amylase of family GH13_37. The specific ability towards raw rice starch has never been described before, and this makes AmyP a promising candidate for use as a novel enzyme in rice starch processing.

Confocal laser scanning microscopy of dextran-rice starch mixtures.

The microstructure of rice starch and dextran-rice starch mixtures was studied using confocal laser scanning microscopy (CSLM) and scanning electron microscopy (SEM). Surface pores and channels of rice starch were looked for. Channels could not be found in rice starch granules after reaction with 3-(4-carboxybenzoyl)-quinoline-2-carboxaldehyde (CBQCA). Fluorescein-labeled dextran was mixed with rice starch in order to locate hydrocolloid molecules in hydrocolloid-rice starch mixtures. The results showed that FITC-dextran (ave. Mw 4000; FD4) penetrated into raw rice starch granules, with the degree of penetration varying from granule to granule. FD4 could penetrate throughout cooked rice starch granules. FITC-dextran with an average Mw of more than 10,000 could not penetrate either raw or cooked rice starch granules.

Utilization of different carbohydrate sources and starch forms by bagrid catfish (Mystus nemurus) (Cuv &amp; Val)

Two experiments were conducted to ascertain the utilization of different carbohydrate sources and different forms of starch present in bagrid catfish (Mystus nemurus) fry. The nutritional quality and starch forms of cornstarch, dextrin, broken rice, and sago flour were evaluated in a 4 × 2 factorial design. All diets were formulated to be isonitrogenous (400 g kg−1 crude protein) and isolipidic (150 g kg−1 crude lipid), fed to triplicate groups of bagrid catfish fry (initial weight 6.04 ± 0.04 g). Growth studies, enzymatic response and postprandial plasma glucose were observed. A two-way anova (P > 0.05) analysis of the data obtained showed that the final body weight, specific growth rate (SGR) and food conversion ratio (FCR) were significantly affected by carbohydrate source, but not significantly affected by starch form. Fish fed broken rice and corn starch had similar SGR and FCR compared to fish fed with dextrin and sago flour. The postprandial plasma glucose trend in fish fed with corn starch and broken rice showed a gradual increase while sago flour and dextrin-fed fish peaked at 2 and 3 h, respectively. Lipogenic enzyme (G6PDH) activity were more pronounced than gluconeogenic enzyme (ME) in M. nemurus irrespective of carbohydrate source and starch form. Therefore, we suggest that raw broken rice and corn starch are suitable carbohydrate sources in the M. nemurus diet.

Formation, characterization, and glucose response in mice to rice starch with low digestibility produced by citric acid treatment

The optimum conditions for producing rice starch enriched in slowly digestible and resistant fractions by citric acid treatment determined by a response surface methodology (RSM) model equation, were: reaction temperature, 128.4 °C; reaction time, 13.8 h; and citric acid, 2.62 mmol/20 g starch. The slowly digestible and resistant starch fractions of the optimally acid-treated rice starch totalled 54.1%, which was 28.1% higher than the control. The slowly digestible and resistant fractions of the acid-treated rice starch did not differ significantly after heat treatment, whereas those of raw rice starch decreased by 49.6–63.8%, depending on the type of heat treatment (cooking at 100 °C or autoclaving). The slowly digestible fraction of the acid-treated starch increased by 8.9–14.2%. After autoclaving, the glucose response of the acid-treated starch was lower than untreated starch, but similar to that of Novelose 330. After heat treatment, the rate of blood glucose decrease was slower for the acid-treated starch than for Novelose 330. Compared to raw rice starch, the acid-treated starch exhibited increases in apparent amylose content, blue value, dextrose equivalent, cold-water solubility and transmittance, and decreases in wavelength of maximum absorbance, viscosity, and gel-forming ability.

Transglycosylation reaction and raw starch hydrolysis by novel carbohydrolase fromLipomyces starkeyi

A novel carbohydrolase, which is a DXAMase, containing both dextranase and amylase equivalent activities, was purified fromLipomyces starkeyi KSM22. The purified DXAMase was also found to hydrolyze cellobiose, gentiobiose, trehalose and melezitose, while disproportionation reactions were exhibited with various di-and tri-saccharides, such as maltose, isomaltose, gentiobiose, kojibiose, sophorose, panose, maltotriose, and isomaltotriose with various kinds of oligosaccharides produced as acceptor reaction products. Furthermore, the purified DXAMase hydrolyzed raw waxy rice starch and produced maltodextrin to the extent of 50% as a glucose equivalent.

Production of an amylase-degrading raw starch by Gibberella pulicaris.

An endophytic fungus, Gibberella pulicaris, produced an amylase which degraded raw starches from cereals and other crops including raw potato, sago, tapioca, corn, wheat and rice starch. In each case, glucose was the main product. Among the raw starches used, raw potato starch gave the highest enzyme activity (85 units mg−1 protein) and raw wheat starch the lowest (49 units mg−1 protein). The highest amylase production (260 units mg−1 protein) was achieved when the concentration of raw potato starch was increased to 60 g l−1. Optimum hydrolysis was at 40 °C and pH 5.5.

Direct fermentative production of lactic acid on cassava and other starch substrates

Lactobacillus amylovorus utilized raw corn, rice and wheat starch medium to produce lactic acid with a productivity of 10.1, 7.9 and 7.8 g lactic acid/L, but had lower productivities of 4.8 g/L and 4.2 g/L on cassava and potato starch in basal medium respectively. When peptone (1%) is added to basal medium with cassava starch as substrate, conversion rate increased from 43% conversion to 70% conversion (7.7 g lactic acid/L). The availability of some components of protein in corn starch is assumed to be the reason for high lactic acid production as compared to that of cassava starch.

Crystallinity of Raw Rice Starch Granules as Indexed by Corrosion with Hydrochloric Acid and Amylase

AbstractAfter 15 d in 2.2N HCl at 35°C, residual starch of 34 granular rice starches differing in apparent amylose content (AC) and final gelatinization temperature (GT) ranged from 1.3 to 20.8% and was verified to correlate significantly with GT (r = 0.69**) and AC (r = 0.44**). Residual starch after 5 h corrosion with crude Chalara paradoxa amylase ranged from 0 to 29.4% and also correlated significantly with GT (r = 0.45**) and AC (r = 0.70**). The amounts of residual starch after Lintnerization and after C. paradoxa amylase digestion were significantly correlated (r = 0.72**).

Raw Starch Digestion by α‐Amylase and Glucoamylase from Chalara paradoxa

AbstractGlucoamylase and α‐amylase of Chalara paradoxa were separated by hydrophobic column chromatography using butyl‐Toyopearl 650M. The α‐amylase showed the highest activity at pH 5.5 and 45°C, and was stable in the pH range of 5.5–6.5 and at temperatures lower than 40°C. The glucoamylase showed the highest activity at pH 5.0 and 45°C, and was stable in the pH range of 4.0–7.5 and at temperatures lower than 45°C. The molecular mass of the α‐amylase and glucoamylase estimated by SDS polyacrylamide gel electrophoresis was 80,000 and 68,000, respectively. Both glucoamylase and α‐amylase could digest more effectively raw rice starch and raw corn starch than raw sago starch and raw potato starch. 2% raw rice starch in 10 ml solution was digested by more than 90% by 100 units of each amylase. When these amylases were used combined, raw corn starch was more effectively digested than they were used singly. This cooperative action in raw corn starch digestion was also observed when. C. paradoxa α‐amylase and R. niveus glucoamylase were combined.

Nature of Starch Crystallinity in Parboiled Rice

AbstractA‐type X‐ray diffraction spectra of raw rice was weakened upon mild parboiling and completely disappeared in moderately severe parboiled rice. A feeble V pattern of lipid‐amylose complex appeared in its place. There was no unambiguous evidence of a B‐type spectra of retrograded starch, although partial and weak B‐like spectra could be seen. Differential scanning calorimetry showed that raw rice flour and starch had a large gelatinization and a small lipid‐amylose endotherm, the latter disappearing after defatting. The gelatinization endotherm first decreased and eventually disappeared in samples with moderately severe parboiling, but a small lipid‐amylose endotherm was visible in most parboiled rice samples. On the whole, parboiled rice appeared largely amorphous with only minor crystallinity, and the peculiar properties of parboiled rice could not be definitely ascribed to a definite crystalline form of starch.