Alkali-treated Starch Research Articles

The impact of sodium carbonate on physico-chemical properties and cooking qualities of starches isolated from alkaline yellow noodles

The physicochemical and cooking properties of wheat starch isolated from alkaline yellow dough treated with sodium carbonate (Na2CO3; 0–3.2 g/100 g) were investigated. With increasing Na2CO3 addition, swelling power increased from 7.28 to 10.70 g/g. X-ray diffraction showed no changes in crystalline patterns while the relative crystallinity decreased from 30.11% to 23.13%. Differential scanning calorimetry results suggested that alkaline salt shifted the gelatinization peak of starch to higher temperatures. The values of pasting viscosity and pasting temperature in alkali-treated starch increased and decreased, respectively. Farinograph results revealed the strengthened structure of dough with alkali-treated starch that was manifested by an increase in the dough development time and dough stability time. Cooking loss and rehydration values of noodles prepared from alkali-treated starch increased by 42% and 36%, respectively. The results suggested that Na2CO3 affected starch crystalline structure, swelling power, gelatinization, pasting properties, starch-gluten interactions and cooking characteristics of noodle products.

Alkali-treated starches as a new class of templates for CaCO3 spherulite formation: Experimental and theoretical studies

Biomineralization is the study of minerals produced by biomaterials or living organisms, and it has attracted considerable attention in industry and fundamental research. Here, for the first time, the roles of alkali-treated mung bean (MB) and cassava (CS) starches as templates for calcium carbonate (CaCO3) spherulite formation were investigated by bulk rheology and molecular dynamics (MD) simulations. The rheological results, including yield stress, flow behavior index, consistency coefficient, and hysteresis area of alkali-treated MB and CS starch suspensions containing Ca2+, revealed that the Ca2+ induced the folding of starch chains via Ca2+ crosslinking, leading to aggregation of starch–Ca2+ complexes. After the starch films were fabricated from the suspensions, CaCO3 spherulites were observed inside the films. The size and number of the spherulites increased with increasing concentration of Ca2+ in the suspensions as a result of an increase in nucleation sites needed for spherulite growth. Moreover, to gain a deeper understanding of the interactions between Ca2+ and starch and of the formation of the nucleation sites for spherulite growth, MD simulations were performed. Our findings pave the way for the design of new biomaterial-based templates, which can efficiently control crystal shape and size of CaCO3.

Physicochemical properties of modified trifoliate yam starches

Physicochemical properties of modified trifoliate yam starches were determined. Trifoliate yam starches were harvested and the starch was extracted. The extracted starch was modified using four methods (acid and alkali treatment, oxidation and acetylation). Colour and physicochemical properties of the modified starches were determined. Colour of pre-gelatinized trifoliate yam starch was significantly different (p<0.05) from other starches. The colour was yellowish/reddish while other starches were lighter in colour. The structures of untreated, oxidized, pre-gelatinized and acetylated starches were polygonal in shape. Granule sizes of native and modified trifoliate yam starches ranged from 2.53 to 3.86 μm. Amylose content of trifoliate yam starches ranged from 10.01 to 16.17%. Swelling power of pre-gelatinized starch increased from 2.15 at 60o C to 3.00 at 70 oC but the values decreased at 80 to 90o C. Acid-treated starch exhibited higher paste clarity at refrigerated temperature than ambient temperature but at ambient temperature, oxidized starch had high paste clarity during storage. Acid and alkali-treated starches had higher water exudate at day 0 which later decreased with storage. Acetylated starch had higher peak viscosity (3833.00 cP). Acid and alkali treatment reduced the viscosities and had low freezethaw stability.Keywords: Colour, Modification, Physicochemical, Trifoliate yam starch

Effect of CaCl2 on the formation of Ca-induced starch aggregates and spherulitic structure in dried starch film

ABSTRACTThis study investigated structure-forming process of Ca–starch aggregates and CaCO3 in alkali-treated starch suspensions and dried films. It was found that the addition of CaCl2 in starch suspensions (pH 13.4) induced the formation of Ca–starch aggregates having different flow behaviors from the suspensions in the absence of CaCl2. Drying the Ca–starch suspensions at 43°C to obtain dried starch films further induced the formation of CaCO3 spherulitic crystals (5–7 µm) homogeneously embedded in the films shown by X-ray diffractometry and scanning electron microscopy. This study revealed the use of alkali-treated starches as the template for CaCO3 crystallization during dehydration.

Scalable preparation, characterization, and application of alkali-treated starch as a new organic base catalyst

Preparation, characterization, and application of alkali starch (AS) given by dry co-grinding of starch and alkali is described in this work. Grinding using a mortar (agate) and pestle or, more conveniently, a ball mill has been found to be satisfactory for the preparation of the AS. The AS products were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) and x-ray fluorescence (XRF) analyses. The base capacities of ASs were 4.25–4.45 mmol/g, respectively. AS is a low cost and easy to handle base catalyst that showed promising catalytic performance in the synthesis of a dihydroquinazoline-based antibacterial drug that involves tandem hydration or decarboxylative amidation, imination, and Aza-Michael reactions.

WITHDRAWN: Scalable preparation, characterization, and application of alkali-treated starch as a new organic base catalyst

WITHDRAWN: Scalable preparation, characterization, and application of alkali-treated starch as a new organic base catalyst

Effect of alkali-treatment on physicochemical, pasting, thermal, morphological and structural properties of Horse Chestnut (Aesculus indica) starch

Horse Chestnut (Aesculus indica) starch (HCN) was treated with 0.1, 0.25 and 0.5 % (w/v) alkali (NaOH) for 0, 5, and 10 days at ambient temperature (25 °C). Native and alkali-treated starches were characterized for physicochemical, pasting, thermal, morphological and structural properties. The amylose content of the starch decreased after alkali treatment from 26.10 (native) to 13.56 %. Swelling power and solubility increased significantly for treated starch as compared to native HCN starch. Pasting properties of treated starches revealed significant decrease in peak, breakdown and setback viscosity whereas pasting temperature was slightly affected. Gel firmness of native starch was decreased upon treatment from 0.850 to 0.219 N. Thermal properties showed increase in onset, peak and conclusion temperatures at higher concentration of alkali and treatment time. Morphology revealed that the granular shape of starch was affected when treated with higher concentration of alkali. X-ray diffraction of treated starches showed a similar profile but the relative crystallinity decreased with the severity of the treatment from 32.78 (native) to 27.64 %. The effect of alkali on the crystalline structure including short-range ordered structure was not pronounced with a similar trend for all the starches.

Structural and functional properties of alkali-treated high-amylose rice starch

Native starches were isolated from mature grains of high-amylose transgenic rice TRS and its wild-type rice TQ and treated with 0.1% and 0.4% NaOH for 7 and 14days at 35°C. Alkali-treated starches were characterised for structural and functional properties using various physical methods. The 0.1% NaOH treatment had no significant effect on structural and functional properties of starches except that it markedly increased the hydrolysis of starch by amylolytic enzymes. The 0.4% NaOH treatment resulted in some changes in structural and functional properties of starches. The alkali treatment affected granule morphology and decreased the electron density between crystalline and amorphous lamellae of starch. The effect of alkali on the crystalline structure including long- and short-range ordered structure was not pronounced. Compared with control starch, alkali-treated TRS starches had lower amylose content, higher onset and peak gelatinisation temperatures, and faster hydrolysis of starch by HCl and amylolytic enzymes.

Effect of alkali treatment on structure and function of pea starch granules

The effect of alkaline treatment on the structural and functional properties of pea starch granules was studied using a range of characterization methods including amylose content, scanning electron microscopy (SEM), X-ray diffraction (XRD), 13C nuclear magnetic resonance (NMR), swelling power, differential scanning calorimetry (DSC), the Rapid Visco Analyser (RVA) and in vitro digestibility. The amylose content decreased by about 20–25% after 15days of alkaline treatment and there were small decreases in relative crystallinity and double helix content. Deformations were observed on the surface of alkali-treated granules, and there was evidence of adhesion between some of the granules. There was a 25–30% reduction in peak and final RVA pasting viscosities, but only a small reduction in swelling power. The endothermic transition of alkali-treated starch was broadened with a shift of the endothermic peak to higher temperature. However, the endothermic enthalpy remained largely unaffected. Alkali-treatment greatly increased the rate of in vitro enzymatic breakdown of the pea starch. More prolonged alkaline treatment for 30days did not cause further significant changes to the structural and functional properties of the starch granules. The effects of alkali on structure and function of pea starch are explained on the basis of limited gelatinization of the granules.

Comparative susceptibilities of sago, potato and corn starches to alkali treatment

The effects of steeping starch (sago, corn, and potato), in 0.025 M of sodium hydroxide for 0, 15, and 30 days at 30 °C, on its granular structure and other physicochemical properties were investigated. Changes in the morphology of starch granules indicated that the alkaline solution affected the granular structure of the starch. Pasting studies showed that the peak viscosity, breakdown, and setback of sago and potato starch decreased significantly, whereas that of corn starch increased significantly, when steeping time was prolonged. Swelling power increased significantly for treated potato and corn starches, but it decreased for sago starch. The amylose content of all alkali-treated starches also decreased significantly after treatment. Onset and peak temperatures of gelatinization (as analyzed with a differential scanning calorimeter) increased significantly, but the enthalpy decreased, for both gelatinization and retrogradation. The results showed that the physicochemical properties of starch of various botanical origins were affected to variable degrees when it was treated with alkaline solution.

Pasting and retrogradation properties of alkali-treated sago ( Metroxylon sagu) starch

Sago ( Metroxylon sagu) starch was treated with 0.1% (w/v) and 0.5% (w/v) alkali (sodium hydroxide, NaOH) for 0, 15, and 30 days at ambient temperature (30 °C). Alkali-treated starches were characterized for pasting properties, retrogradation, intrinsic viscosity, swelling power, and solubility using various physical methods. Increase in swelling power and solubility of the alkali-treated starch could be attributed to the leaching of amylose chain, probably due to the propensity of alkali to attack the amorphous regions of the granules. This was evident by the blue regions (amylose–iodine complex) which were recognizable outside the starch granules when observed using iodine staining microscopy. Partial depolymerization of starch by alkali was also evidenced by a decrease in intrinsic viscosity. Peak viscosity and breakdown of alkali-treated starch were significantly reduced, whereas pasting temperature was not significantly affected. Microscopic examination showed that the granular shape of starch was less affected by alkaline treatment, except for the roughened surface on some granules treated with 0.5% NaOH. The effect of alkali on the crystalline region was not pronounced because the X-ray diffraction pattern was not significantly altered and the birefringence of the alkali-treated starch still remained after 30 days of treatment. Data from pulsed nuclear magnetic resonance and uniaxial compression tests for starch gels stored for 7 days at 4 °C indicated that retrogradation was markedly reduced, possibly due to depolymerization of starch polymer chains. The effects of alkali on pasting and retrogradation properties were more pronounced for starch treated with 0.5% alkali and longer duration.

Studies on Alkali Decomposition of Rice Kernel : 3. A new alkali test using rice flour

Method for eveluating the alkali digestibility of rice flour was investigated. And a rapid alkali test could be done by measuring light transmission rate of alkali-treated flour paste with a modified turvidmeter. The procedure of test is as follows. 500 mg sample of rice flour is put in a flat-bottomed glass container 50 mm in internal diameter. After being wetted wits 1.2ml of distilled water, the sample is added with 25ml of 2.2% potassium hydroxide solution. The flour-alkalii suspension is then stirred magnetically at 120 r. p. m. for 10 minutes on a water bath which is also stirred magnetically and regulated at 40±0.5°C. The paste is cooled with runnihg water to room temperature and set in the measuring apparatus together with glass container. A modified turvidimeter having a light beam of vertical direction was used for measuring light transmission of the paste. Alkali decomposition value is represented by percent light transmission. The procedure can be satisfactorily applied to rice starch sample as well. Compound starch granules in alkali-treated starch pastes of various light transmission rates were observed through a phase-different microscope. And a close relation was revealed between alkali decomposition value and disintegration of starch granules. Rate of light transmission or alkali decomposition value, therefore, may be said to be an adequate indicator for evalualuating the alkali digestibility of pulverized rice whose major component is starch. Rice flour pulverized finer than 120 mesh or coarser than 40 mesh considerably affected the decomposition value. So the test should be done on a fixed mesh of flour within the range of 40 to 120 mesh.