Starch Pretreatment Research Articles

Effects of different pretreatment methods on the degree of substitution, structure, and physicochemical properties of synthesized malic acid sweet potato starch ester.

The preparation of malic acid starch ester (MSE) is mostly carried out using a high temperature method, but there are problems such as high energy consumption, long preparation time, and uneven heating. Microwave technology can be used to overcome these limitations. The semi-crystalline structure of starch granules hinders the modifier's access to the matrix, thus limiting the esterification reaction. Physical techniques can act on the interior of the starch to create a number of active sites, thereby facilitating the reaction of the starch with esterification reagents. Therefore, this study investigated the effect of starch pretreatment by microwave, heat-moisture, and ultrasonic techniques on the degree of substitution (DS), structure, and physicochemical properties of MSE synthesized by the microwave method. The DS of MSE was increased after pretreatments. The modified starch obtained by different pretreatment methods did not show new characteristic peaks, while the MSE synthesized showed new absorption peaks near 1735 cm-1. The granular structure and morphology of the modified starch obtained by microwave and heat-moisture pretreatment were gelatinized and aggregated, while some of the starch particles of the modified starch obtained by ultrasonic pretreatment appeared pore-sized. The relative crystallinity and gelatinization enthalpy of the MSE were reduced, but the crystallization pattern remained as A-type. Overall, the results suggest that various pretreatment methods can enhance the DS of MSE by disrupting the structure of starch. The findings of this study provide theoretical support for improving the DS of esterified starch. © 2024 Society of Chemical Industry.

Synergistic effect of enzymatic pre-treatment and amylose–lipid complex construction on the physicochemical properties of maize starch

In this study, the effects of maltogenic amylase (MAA) pre-treatment and starch–fatty acid complex construction on the physicochemical properties of maize starch (MAS) were investigated. The average chain length of MAA-modified MAS was found to decrease from 18.15 to 14.92. Moreover, MAA pre-treatment of starch induced the formation of a V-type complex. This behaviour was demonstrated by the higher diffraction intensity, enzymatic resistance and short-range ordering of the samples pre-treated with MAA compared with unmodified samples. X-ray diffraction and rheological analysis revealed that the re-crystallisation peak intensities and storage modulus of MAA–MAS–lauric acid (LA)/stearic acid (SA) complexes were lower than those of MAA–starches, MAS–LA/SA complexes and control. The rate of starch re-crystallisation was effectively decreased by the combination of MAA pre-treatment and V-type complex construction. The anti-retrogradation (long-term) characteristics of the tested samples were in the following order: MAA–MAS–LA/SA complexes > MAA–starches > MAS–LA/SA complexes > control.

Correction to: Which one is important to achieve maximum degree of hydrolysis, starch pre-treatment or activated α-amylase: kinetics and mathematical modeling for liquefaction

Correction to: Which one is important to achieve maximum degree of hydrolysis, starch pre-treatment or activated α-amylase: kinetics and mathematical modeling for liquefaction

Pilot-scale bioethanol production from the starch of avocado seeds using a combination of dilute acid-based hydrolysis and alcoholic fermentation by Saccharomyces cerevisiae

BackgroundA processing methodology of raw starch extraction from avocado seeds (ASs) and a sequential hydrolysis and fermentation bioprocess in just a few steps was successfully obtained for the bioethanol production by a single yeast Saccharomyces cerevisiae strain and this research was also to investigate the optimum conditions for the pretreatment of biomass and technical procedures for the production of bioethanol. It successfully resulted in high yields and productivity of all the experiments from the laboratory scale and the pilot plant. Ethanol yields from pretreated starch are comparable with those in commercial industries that use molasses and hydrolyzed starch as raw materials.ResultsBefore the pilot-scale bioethanol production, studies of starch extraction and dilute sulfuric acid-based pretreatment was carefully conducted. The amount of starch extracted from dry and fresh avocado seed was 16.85 g ± 0.34 g and 29.79 ± 3.18 g of dry starch, representing a yield of ∼17% and 30%, respectively. After a dilute sulfuric acid pretreatment of starch, the released reducing sugars (RRS) were obtained and the hydrolysate slurries containing glucose (109.79 ± 1.14 g/L), xylose (0.99 ± 0.06 g/L), and arabinose (0.38 ± 0.01 g/L). The efficiency of total sugar conversion was 73.40%, with a productivity of 9.26 g/L/h. The ethanol fermentation in a 125 mL flask fermenter showed that Saccharomyces cerevisiae (Fali, active dry yeast) produced the maximum ethanol concentration, pmax at 49.05 g/L (6.22% v/v) with a yield coefficient, Yp/s of 0.44 gEthanol/gGlucose, a productivity or production rate, rp at 2.01 g/L/h and an efficiency, Ef of 85.37%. The pilot scale experiments of the ethanol fermentation using the 40-L fermenter were also successfully achieved with essentially good results. The values of pmax,Yp/s, rp, and Ef of the 40-L scale were at 50.94 g/L (6.46% v/v), 0.45 gEthanol/gGlucose, 2.11 g/L/h, and 88.74%, respectively. Because of using raw starch, major by-products, i.e., acetic acid in the two scales were very low, in ranges of 0.88–2.45 g/L, and lactic acid was not produced, which are less than those values in the industries.ConclusionsThe sequential hydrolysis and fermentation process of two scales for ethanol production using the combination of hydrolysis by utilizing dilute sulfuric acid-based pretreatment and fermentation by a single yeast Saccharomyces cerevisiae strain is practicable and feasible for realistic and effective scale-up strategies of bioethanol production from the starch of avocado seeds.

Which one is important to achieve maximum degree of hydrolysis, starch pre-treatment or activated α-amylase: kinetics and mathematical modeling for liquefaction

Which one is important to achieve maximum degree of hydrolysis, starch pre-treatment or activated α-amylase: kinetics and mathematical modeling for liquefaction

Effect of freezing-thawing pre-treatment on enzymatic modification of corn and potato starch treated with activated α-amylase: Investigation of functional properties

Owing to the semi-crystalline structure of native starch granules, enzymatic modification is low efficient. In order to achieve highly effective amylolysis by α-amylase, freezing/thawing pre-treatment (FTF) of starch was performed to produce damaged starch with raised surface area. Afterwards, the effect of non-activated and activated α-amylase by the concomitant performance of ultrasonication (64.5 W, 25 + 40 kHz, 5 min) and Ca2+ ions (12.5 and 25 mM) on starch digestibility were investigated. Corn (NCS) and potato (NPS) starches were suspended in water by being exposed to activated and non-activated α-amylase (0.15% w/v) for a period of 10 h at a temperature of 25 °C. The physicochemical, morphological, and structural properties of native, FTF starches and hydrolyzed starches were studied. An increasingly damaged starch was the result of FTF according to the porous and cracking surface observed on starch granules. FTF of potato (PFTF) and corn (CFTF) starches exposed to non-activated and activated α-amylase showed a significantly greater percentage of hydrolysis, consequently destroyed the integrity of starch granules. The ratio of 1047/1022 cm− 1 reduced from 1.112 to 0.947 (NPS), 0.987 to 0.670 (PFTF), 1.293 to 1.154 (NCS) and 1.211 to 1.038 (CFTF) after being treated with activated α-amylase by 25 mM Ca2+ + 64.5 W sonication; additionally, relative crystallinity decreased respectively from 34.1% to 13.8% (PFTF) and 39.3%–17.7% (CFTF). Significantly low pasting viscosities (determined by RVA) along with the gelatinization temperature and enthalpy (determined by DSC) of FTF treated with α-amylases could be the reason behind the degradation of granular and molecular structures and low swelling power as well.

Dry extrusion pretreatment of cassava starch aided by sugarcane bagasse for improved starch saccharification

The enzymatic hydrolysis of native starch lacks efficiency because starch is mostly confined in semi-crystalline granules. To address the challenges associated with gelatinization and render native cassava starch (CS) amenable to enzymatic hydrolysis (enzyme cocktail from Aspergillus awamori and Trichoderma reesei), dry-extrusion pretreatment of CS mixed with sugarcane bagasse (SB) was studied. Results showed that among the CS:SB mass ratios studied (1:1; 1:0.5 and 1:0.25), extruded CS:SB (1:0.25) gave the highest 3-hour glucose yield (71.5%) after enzymatic hydrolysis. Extrusion reduced CS:SB (1:0.25) crystallinity by 78% and increased the intensity of all major FTIR absorption bands by 67–202%. The optimum 3-hour glucose yield from extruded CS:SB (1:0.25) hydrolysis was 74.1%, which was 330% higher than from untreated CS. The water absorption and solubility indices of the treated biomass increased by 145% and 12,640%, respectively under the optimum conditions, aiding the hydrolysis process. The dry extrudates were easy to manipulate and store.

Improved production of gamma-cyclodextrin from high-concentrated starch using enzyme pretreatment under swelling condition

High substrate viscosity during the production process suppressed the formation of gamma-cyclodextrin (γ-CD) from starch. Although liquefaction can be carried out by enzymes with high temperature optimum, some CGTases of interest are not suitable due to loss of activity at the gelatinization temperature. In order to apply a gamma-cyclodextrin glucosyltransferase (γ-CGTase) with an optimum temperature of 50 °C to the liquefaction of 10% w/v cassava starch, an improved process combining moderate heat treatment (30 °C increased to 70 °C) with enzymatic treatment was established. The substrate viscosity dropped from 2456 to 23 cP after the pretreatment, and the rate of γ-CD production increased from 10.43 to 26.34%. This process was further applied to the liquefaction of 30% w/v cassava starch, and the pretreated substrate was finally converted into 21.81% γ-CD. In general, evaluation indicators and basic principles of starch pretreatment were established, providing a reference for the production of γ-CD.

Enhancement of large ring cyclodextrin production using pretreated starch by glycogen debranching enzyme from Corynebacterium glutamicum

Synthesis of large-ring cyclodextrins (LR-CDs) in any significant amount has been challenging. This study enhanced the LR-CDs production by Thermus filiformis amylomaltase (TfAM) enzyme by starch pretreatment using glycogen debranching enzyme from Corynebacterium glutamicum (CgGDE). CgGDE pretreated tapioca starch gave LR-CD conversion of 31.2 ± 2.2%, compared with LR-CDs produced from non-treated tapioca starch (16.0 ± 2.4%). CgGDE pretreatment enhanced amylose content by approximately 30%. Notably, a shorter incubation time of 1 h is sufficient for CgGDE starch pretreatment to produce high LR-CD yield, compared with 6 h required for the commercial isoamylase. High-Performance Anion Exchange Chromatography coupled with Pulsed Amperometric Detection (HPAEC-PAD) and Gel Permeable Chromatography (GPC) revealed that CgGDE is more efficient than the commercial isoamylase in debranching tapioca starch and gave lower molecular weight products. In addition, lower amount of by-products (linear oligosaccharides) were detected in cyclization reaction when using CgGDE-pretreated starch. In conclusion, CgGDE is a highly effective enzyme to promote LR-CD synthesis from starch with a shorter incubation time than the commercial isoamylase.

Sustainable Hydrogen Production from Starch Aqueous Suspensions over a Cd0.7Zn0.3S-Based Photocatalyst

We explored the photoreforming of rice and corn starch with simultaneous hydrogen production over a Cd0.7Zn0.3S-based photocatalyst under visible light irradiation. The photocatalyst was characterized by UV–vis diffuse reflectance spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The influence of starch pretreatment conditions, such as hydrolysis temperature and alkaline concentration, on the reaction rate was studied. The maximum rate of H2 evolution was 730 μmol·h−1·g−1, with AQE = 1.8% at 450 nm, in the solution obtained after starch hydrolysis in 5 M NaOH at 70 °C. The composition of the aqueous phase of the suspension before and after the photocatalytic reaction was studied via high-performance liquid chromatography, and such products as glucose and sodium gluconate, acetate, formate, glycolate, and lactate were found after the photocatalytic reaction.

In situ dual crosslinking strategy to improve the physico-chemical properties of thermoplastic starch

This study is focused on enhancing the stability of mechanical and chemical properties of thermoplastic starch (TPS) by dual crosslinking strategy through melt processing conditions. The dually crosslinked TPS was prepared by in situ reaction of starch, glycerol, and epichlorohydrin (ECH), resulting in both noncovalent and covalent bond formation. The TPS was characterized by tensile testing, dynamic mechanical analysis (DMTA), rheology, and solubility in water. A substantial increase in tensile strength, Young's modulus, insoluble portion, and stability in water for dually crosslinked TPS was observed in comparison with conventional TPS. The rheology results indicated that the ECH induced the formation of 3D networks and significantly limited the chain mobility of the melted TPS, resulting in an extended relaxation process, which was also verified by DMTA. The suggested strategy avoids any chemical modification pretreatment of starch for introducing covalent bonds into TPS before one-step mixing using the melt processing technique.

Fabrication of starch-based high-performance adsorptive hydrogels using a novel effective pretreatment and adsorption for cationic methylene blue dye: Behavior and mechanism

Herein, NaOH solution of a finite concentration was used to pretreat starch, which serves a novel effective pretreatment. A starch-based high-performance adsorptive hydrogel (STAH) was successfully prepared by grafting polyacrylic acid (PAA) onto starch and then crosslinking with N,N'-methylene-bisacrylamide (MBA). This adsorbent was employed to adsorb typical organic cationic dye contaminants (methylene blue (MB)) from high concentration effluents. The effect of the pretreatment time of starch on adsorption capacity of STAH was investigated in detail based on starch molecular weight, solid state 13C nuclear magnetic resonance spectra and grafting parameters. The results suggested that the optimal adsorbent (STAH20) presented the highest grafting parameters (50.06% reaction ratio of C6 in starch, 90.79% grafting efficiency, and 248.49% grafting ratio of PAA). STAH20 exhibited maximum adsorption capacity (2967.66 mg/g) in optimal conditions and excellent reusability after 4 rounds of recycling. The adsorption process of STAH20 for MB was consistent with the Langmuir model, obeyed the pseudo-first order model with intra-particle diffusion, and was endothermic and spontaneous. Using this pretreatment, the semi-crystalline structure of starch was destroyed, and numerous hydroxyl groups were gradually exposed with time, which is conducive to the graft reactions. The number of –COOH/ –COO– groups increased, which significantly enhances the hydrogen-bonding interaction and electrostatic interaction between STAH and MB and improves the adsorption capacity. Our study provides a method for low-energy, inexpensive, effective and simple starch pretreatment for the fabrication of STAH that exhibits significant potential for application in the removal of organic cationic dye contaminants.

Study on the mechanism of ultrasound-accelerated enzymatic hydrolysis of starch: Analysis of ultrasound effect on different objects

Enzymatic hydrolysis of starch is an important process in the food industry. In the present work, ultrasound was introduced in glucoamylase pretreatment, starch pretreatment and mixed reaction system treatment to enhance starch hydrolysis efficiency. These different processes were studied to explore the mechanism of ultrasound in promoting enzymatic reactions. The hydrolysis degree of starch was determined via measuring the reducing sugar yield. Ultrasound caused enzyme inactivation under high temperatures, high ultrasonic power and long-time treatment, especially at high temperatures exceeding 65 °C. Ultrasound pretreatment of starch before enzymolysis led to the furtherance of starch hydrolysis degree. Meanwhile, sonicating the mixed enzymatic reaction system below 65 °C promoted starch hydrolysis significantly, inducing more than five- fold growth in the degree of starch hydrolysis as much as the ultrasound pretreatment caused. Molecular weights analysis conducted by the MALLS system reflected the enormous damage of starch molecules caused by ultrasound. The amylose contents and chain length distributions of samples were separately analyzed by iodine binding method and size exclusion chromatography. The results of the two experiments illustrate that ultrasound could promote the enzymatic hydrolysis of amylopectin, which is harder for glucoamylase to hydrolyze compared to amylose.

Discovery and Characterization of a Novel Method for Effective Improvement of Cyclodextrin Yield and Product Specificity

Cyclodextrins(CDs) are widely used in food, pharmaceuticals, drug delivery, and chemical industries and in agriculture and environmental engineering. To improve the yield and selectivity of CDs, this work presented a facile, scalable and efficient enzymatic synthesis of β-CD from starch using β-cyclodextrin glycosyltransferase (CGTase, EC 2.4.1.19) from Bacillus cereus. First, we found that the pretreatment of starch dramatically influenced CDs yield that was related to the structure and molecular weight of the substrate starch. Second, alcohol solvents influenced the yield and product selectivity of CDs; tertiary alcohols enhanced CDs yield(from 54.95% to 68.21%) and secondary alcohols increased the product selectivity(β-CD/γ-CD changed from 6.25 to 8.05). Fluorescence quenching analysis showed that the binding constants and entropy of the solvents influenced the yield and product selectivity, respectively. In conclusion, the results demonstrate that this study provides a promising method for the industrial production of β-CD.

Effect of photocatalytic pretreatment of potato starch for bioethanol production using Saccharomyces cerevisiae during simultaneous saccharification-fermentation (SSF)

In this study, the effect of the photocatalytic (PC) pre-treatment with TiO2 during gelatinization (GE) stage in a simultaneous saccharification-fermentation process (SSF) of potato starch for bioethanol production was evaluated. Maximum amount of reducing sugars was 119.3, 114.6 and 104.8 g l-1 for PC→GE, GE→PC and reference (without PC), respectively while bioethanol concentration it increased gradually up to a maximum amount of 128.21, 106.74 and 85.91 g l-1 after 30 h, for PC→GE, GE→PC and reference (without PC), respectively. These results were consistent with the reducing sugars concentration, because bioethanol concentration increased slightly during 18–30 h of fermentation. Although enzymatic activity (ʋmax) for reactions was similar, in reference (without PC pre-treatment) it not promoted quick substrate conversion into ethanol, despite showing the higher affinity enzyme-substrate (Km). Considering traditional potato starch hydrolysis, PC pre-treatment shortened the reaction time of the biological reactions. Thus, the PC pre-treatment of potato starch for bioethanol production could be an environmentally feasible process without acid and alkali addition.

Synthesis, characterization and application of TiO2–Bi2WO6 nanocomposite photocatalyst for pretreatment of starch biomass and generation of biofuel precursors

This study explores a novel photocatalytic approach for the conversion of complex biomass into smaller molecular units for their utility in generation of biofuel precursors. Following hydrothermal method, TiO2/Bi2WO6 nanocomposite photocatalyst for different ratio of TiO2 viz. 15% and 25% by weight have been synthesized. The efficiency of photodegradation of organic molecule is determined. Composite loaded with 25% TiO2 found to represent maximum photocatalytic efficiency of 99.9%. The structural and optical properties of the synthesized photocatalyst nanomaterial were characterized. A band gap of 2.7 eV was observed for 25% TiO2 composition which displayed an excellent visible light photoactivity, examined by removal of Rhodamine B. We further observe a four-fold higher photocatalytic activity in this composite compared to pristine Bi2WO6. Using this composite, solar energy is harvested to perform photocatalytic fragmentation of a biopolymer, namely starch, to derive smaller molecule precursors. Colorimetric analysis of reducing sugars from the degraded biomass quantifies the monomarization of starch. The linear chain molecular fragments thus formed were further analyzed by Raman, FTIR and ESI-MS. The results demonstrate photocatalytic pretreatment of starch by nanocomposite of TiO2/Bi2WO6 resulted in the formation of organic precursors that are common feedstock for the microbiota of anaerobic methanation and ethanol fermentation. We therefore conclude that photocatalytic pretreatment of biomass can be utilized for hydrolysis and partial acedogenesis of biomass in biofuel conversion processes. Such an approach represent environmentally benign way to convert biomass waste to biofuel.

Heat pretreatment improves the enzymatic hydrolysis of granular corn starch at high concentration

Abstract Heat pretreatment was investigated as a way to improve the α-amylase-catalyzed hydrolysis of granular corn starch at high concentration (45%, w/w). Native and preheated starches were hydrolyzed in the granular state for 1 h at 40 °C using a commercially available α-amylase. The initial dextrose equivalent (DE) value of the native granular starch (8.0%) increased significantly (to 12.6%) after pretreatment at 60 °C for 15 min. Microscopic analysis of the starch granules indicated that heat pretreatment increased the number and size of the pores and pinholes on the granule surface, which facilitated the adsorption and subsequent penetration of enzyme molecules. Furthermore, the amylose present in amorphous regions leached rapidly when corn starch was incubated at 60 °C, suggesting weaker interactions within the granules. The DE value of the hydrolysate showed a linear dependence on the amount of amylose that leached during the course of heat pretreatment (R 2 = 0.9771). Mobilization of amylose chains within the granule, caused by the heat pretreatment, may have allowed the enzyme to make greater use of amylose, which is its primary substrate during starch granule hydrolysis. In addition, a 35% reduction in the K m value showed that heat pretreatment increased the affinity of α-amylase for the starch granules. This can be attributed to the mobilization of amylose chains within the granule and expansion of the surface pinholes. These effects demonstrate that proper heat pretreatment of granular starch before amylolysis has great potential in industry.

Effects of heat pretreatment of starch on graft copolymerization reaction and performance of resulting starch-based wood adhesive

In this study, effects of starch heat pretreatment at 70, 80 and 90°C on graft copolymerization reaction with vinyl acetate (VAc) and the performance of the resulting starch-based wood adhesive (SWA) were investigated. It was shown that SWA pretreated at 90°C achieved the best performance. At this temperature, the bonding capacity improved by 17.84% compared to the adhesive synthesized without heat pretreatment and the viscosity increased by 18.16% after 7 free-thaw cycles, much better than other samples. Scanning electron microscopy (SEM) and polarizing microscopy demonstrated that structures of starch granules were fully damaged after heat pretreatment at 90°C. The reaction took place not only on the surface of starch granules, but also internally, leading to improvement in the grafting amounts and grafting efficiency by 42.86% and 39.03%, respectively. This was further confirmed by Fourier transform infrared spectroscopy (FT-IR), Confocal Raman microscopy (CRM) and X-ray photoelectron spectroscopy (XPS), which also showed better reaction homogeneity both between different starch granules and from granule surface to its internal structure.

Optimization of large-ring cyclodextrin production from starch by amylomaltase from Corynebacterium glutamicum and effect of organic solvent on product size.

To increase yield of starch conversion to large-ring cyclodextrins (LR-CDs) by amylomaltase from Corynebacterium glutamicum (CgAM). In this work, LR-CDs produced from pea, tapioca, corn, potato, rice and glutinous-rice starch by the recombinant CgAM were analysed by High-Performance Anion-Exchange Chromatography Using Pulsed Amperometric Detection (HPAEC-PAD). Among these, pea starch gave the highest yield of LR-CDs. Pretreatment of pea starch with isoamylase prior to incubation with CgAM resulted in the increase in LR-CD products by 20%. Surprisingly, CgAM converted starch into LR-CDs within a wide pH range (pH 5·5-9·0). LR-CD syntheses at alkaline pH or at a long incubation time favoured low-degree of polymerization (DP) products (CD22-CD32). Addition of 5-15% dimethyl sulfoxide (DMSO) promoted the synthesis of medium-DP species (CD33-CD43) by 10-25%. Pretreatment of pea starch with isoamylase could enhance the yield of LR-CDs. The ratio of LR-CD products depends on pH, incubation time and addition of organic solvents such as DMSO. LR-CD yield can be increased by thorough optimization of starch types, starch concentrations, enzyme activities, pH and incubation times. This study is the first report of the effect of organic solvents on LR-CD production by amylomaltase.

Effect of pretreatment on the enzymatic synthesis of rosin acid starch

Esterification reaction efficiency was improved by pretreatment of starch, and the high DS of RAS was achieved.