Reactive Extrusion as a Pretreatment in Cassava (Manihot esculenta Crantz) and Pea (Pisum sativum L.) Starches to Improve Spinnability Properties for Obtaining Fibers.

Starch is a biocompatible and economical biopolymer in which interest has been shown in obtaining electrospun fibers. This research reports that cassava (CEX) and pea (PEX) starches pretreated by means of reactive extrusion (REX) improved the starches rheological properties and the availability of amylose to obtain fibers. Solutions of CEX and PEX (30-36% w/v) in 38% v/v formic acid were prepared and the rheological properties and electrospinability were studied. The rheological values indicated that to obtain continuous fibers without beads, the entanglement concentration (Ce) must be 1.20 and 1.25 times the concentration of CEX and PEX, respectively. In CEX, a higher amylose content and lower viscosity were obtained than in PEX, which resulted in a greater range of concentrations (32-36% w/v) to obtain continuous fibers without beads with average diameters ranging from 316 ± 65 nm to 394 ± 102 nm. In PEX, continuous fibers without beads were obtained only at 34% w/v with an average diameter of 170 ± 49 nm. This study showed that starches (20-35% amylose) pretreated through REX exhibited electrospinning properties to obtain fibers, opening the opportunity to expand their use in food, environmental, biosensor, and biomedical applications, as vehicles for the administration of bioactive compounds.

Effect of Microwave Irradiation on Acid Hydrolysis of Faba Bean Starch: Physicochemical Changes of the Starch Granules.

Starch is the most abundant carbohydrate in legumes (22-45 g/100 g), with distinctive properties such as high amylose and resistant starch content, longer branch chains of amylopectin, and a C-type pattern arrangement in the granules. The present study concentrated on the investigation of hydrolyzed faba bean starch using acid, assisted by microwave energy, to obtain a possible food-grade coating material. For evaluation, the physicochemical, morphological, pasting, and structural properties were analyzed. Hydrolyzed starches developed by microwave energy in an acid medium had low viscosity, high solubility indexes, diverse amylose contents, resistant starch, and desirable thermal and structural properties to be used as a coating material. The severe conditions (moisture, 40%; pure hydrochloric acid, 4 mL/100 mL; time, 60 s; and power level, 6) of microwave-treated starches resulted in low viscosity values, high amylose content and high solubility, as well as high absorption indexes, and reducing sugars. These hydrolyzed starches have the potential to produce matrices with thermo-protectants to formulate prebiotic/probiotic (symbiotic) combinations and amylose-based inclusion complexes for functional compound delivery. This emergent technology, a dry hydrolysis route, uses much less energy consumption in a shorter reaction time and without effluents to the environment compared to conventional hydrolysis.

Effect of amylose/amylopectin content and succinylation on properties of corn starch nanoparticles as encapsulants of anthocyanins.

In this study, succinylated nanoparticles from normal (NPS-N), high-amylose (NPS-H), and high-amylopectin corn starch (NPS-W) were synthesized, characterized, and studied for the nanoencapsulation of the Ardisia compressa anthocyanins. The nanoparticle‒anthocyanin interaction was also investigated. The succinylated starch nanoparticles (S-SNPs) had hydrodynamic sizes of 65-390 nm, degrees of substitution (DS) of 0.014-0.032, ζ-potential values of up to -34 mV and a nanocolloid behavior. NPS-N and NPS-W showed the highest (p < 0.05) encapsulation efficiencies (EE) (52 and 49 %, respectively) compared than NPS-H (45 %). Thereby, the lowest DS obtained, and the branched amylopectin structure favored the EE. The nanoparticle-anthocyanin interaction occurred through hydrophobic and electrostatic interactions and influenced significantly (p < 0.05) the hydrodynamic size and surface properties of the resulting nanocapsules. The relative crystallinity (RC) decreased significantly (p < 0.05) in the S-SNPs, but the nanocapsules mostly experimented a structural recrystallization and showed melting temperatures>150 °C.

High-energy alkaline milling as a potential physical and chemical cornstarch ecofriendly treatment to produce nixtamalized flours.

In this study, hard corn grains were nixtamalized (alkali-heat treatment) by a high-energy ball mill to investigate the effects on its physicochemical, textural, and microstructural properties. Ball milling modifies the structure and properties of cornstarch. The gelatinization peak of starch was evidenced and thermal and pasting properties were significantly affected. With regard to rheological properties, the viscosity peak increased from 2454 cP in traditional nixtamalized flour to 4294 cP in high-energy milling treatments with 1.4% of Ca(OH)2 and 20% moisture content, C1.4, while enthalpy ranged from 3.5 to 0.34 J/g, respectively. High-energy milling influenced the Fourier-Transform InfraRed Spectroscopic (FT-IR) patterns. All of the samples of the corn-grain starches presented the typical A-type X-ray diffraction pattern. The crystallinity of starch from CG showed a lower intensity in peaks 2θ ~ 15 and 23° compared with starch from WG and YG. The textural properties of the masas were influenced, adhesiveness was reduced, but cohesiveness was increased by the addition of Ca(OH)2. In the structural characterization by E-SEM, the control presented a greater amount of agglomerated starch granules, followed by the high-energy milling treatments. The results suggest that high-energy alkaline milling could be a potential physical and chemical method to modify corn-starch properties and obtain nixtamalized products.

Microencapsulation of Red Sorghum Phenolic Compounds with Esterified Sorghum Starch as Encapsulant Materials by Spray Drying.

Phenolic compounds with antioxidant properties are highly sensitive molecules, which limits their application. In response, extruded esterified starch has been proposed as efficient encapsulating material. In this work, we aim to describe the encapsulation of red sorghum phenolic compounds by spray drying using extruded phosphorylated, acetylated and double esterified sorghum starch as wall material. Their respective encapsulation yields were 77.4, 67.4 and 56.8%, and encapsulation efficiency 91.4, 89.7 and 84.6%. Degree of substitution confirmed esterification of the sorghum starch and Fourier transform infrared spectroscopy showed the significant chemical and structural changes in the extruded esterified starch loaded with phenolic compounds. Microcapsules from phosphorylated sorghum starch showed the highest endothermic transition (173.89 °C) and provided a greater protection of the phenolic compounds during storage at 60 °C for 35 days than the other wall materials. Extruded esterified sorghum starch proved to be effective material for the protection of phenolic compounds due to its high encapsulation efficiency and stability during storage.

Optimization of corn starch acetylation and succinylation using the extrusion process.

Starch chemical modification can be used in order to obtain modified starches (MS) with low affinity to water. Acetylated and succinylated starches whose applications as food ingredient depend upon their degree of substitution (DS) may be produced by esterifying starch through the extrusion process (EP). The Food and Drug Administration recommends a DS of 0.2 and 0.05 for acetylated and succinylated starches, respectively. The objective of this study was to find mathematical models to obtain the optimum values of DS, Water absorption Index (WAI) and Water Solubility Index (WSI) for MS with safe-for-food-use DS and low affinity to water, modifying the starches by acetylation and succinylation using EP. The process variables were Barrel Temperature (BT, 80-160 °C), Screw Speed (SS, 100-200 rpm) and Reactant Concentration (RC, Acetylation, 0-13% and Succinylation, 0-3%). The best conditions to obtain acetylated starches were RC = 7.88%, BT = 80 °C and SS = 100 rpm, presenting values of DS = 0.2, WAI = 7.67 g/g and WSI = 6.15%. On the other hand, the optimum conditions to obtain succinylated starches were RC = 1.12%, BT = 80 °C and SS = 126 rpm, obtaining values of DS = 0.05, WAI = 3.40 g/g and WSI = 7.92%. These results showed that it is possible to obtain acetylated and succinylated MS with safe-for-food-use levels of DS and with low affinity to water, using EP.

Effects of the Addition of Flaxseed and Amaranth on the Physicochemical and Functional Properties of Instant-Extruded Products.

The addition of flaxseed and amaranth on the physicochemical, functional, and microstructural changes of instant-extruded products was evaluated. Six mixtures with different proportions of amaranth (18.7-33.1%), flaxseed (6.6-9.3%), maize grits (55.6-67.3%) and minor ingredients (4.7%) were extruded in a twin-screw extruder. Insoluble and soluble fiber contents in extrudates increased as the proportions of amaranth and flaxseed increased. However, the highest flaxseed proportion had the highest soluble fiber content (1.9%). Extruded products with the highest proportion of flaxseed and amaranth resulted in the highest dietary fiber content and hardness values (5.2 N), which was correlated with the microstructural analysis where the crystallinity increased, resulting in larger, and more compact laminar structure. The extruded products with the highest maize grits proportion had the highest viscosity, expansion, and water absorption indexes, and the lowest water solubility index values. The mixtures with amaranth (18.7-22.9%), flaxseed (8.6-9.3%), and maize grits (63.8-67.3%) resulted in extruded products with acceptable physicochemical and functional properties.

Mechanical, physical and microstructural properties of acetylated starch-based biocomposites reinforced with acetylated sugarcane fiber.

Fiber-reinforced starch-based biocomposites provide an environmentally friendly alternative to replace petroleum-based plastics. Nevertheless, these materials present structural stability problems owing to their hydrophilicity. Therefore, a chemical modification is usually necessary. Hence, the aim of this research is to obtain biocomposites based on acetylated corn starch (AS), acetylated sugarcane fiber (AcSF) and glycerol. Also, to assess the AcSF content (FC, 0.0-20.0%) and glycerol content (GC, 20.0-30.0%) on their physical, mechanical and microstructural properties. A single-screw extruder and central composite rotatable design were employed. Due to acetylation and possible interaction between matrix-fiber, there was an improvement in water resistance; while the mechanical properties were enhanced by increasing FC up to 12.0%. Biodegradability recorded a range of 24.2-39.3%. Microstructural analysis evidenced the extrusion process effect, chemical modification and new interactions formation. It was found that an optimum blend was of FC = 12.0% and GC = 24.0%. The acetylation of both sugarcane fiber and corn starch allowed us to obtain eco-friendly materials with good mechanical properties and water resistance.

Synthesis and succinylation of starch nanoparticles by means of a single step using sonochemical energy.

In the present research work, esterified nanoparticles with 2-octen-1-ylsuccinic anhydride were synthesized from waxy corn starch, to our knowledge for the first time, in a single step of ultrasonic treatment. First, the ultrasound time to produce non-esterified nanoparticles was studied. The results showed that non-esterified nanoparticles had sizes ranging from 63 to 48 nm, as well as polydispersity indexes (PDI) ranging from 0.458 to 0.224 and ζ-potential values ranging from -16 to -24 mV in ultrasonication times ranging from 20 to 100 min. Succinylated nanoparticles were obtained at 80 min with two degrees of substitution i.e., 0.003 and 0.01, hydrodynamic sizes of 57 and 83 nm, PDI of 0.479 and 0.91, and ζ-potential values of -6.27 and -14.03 mV, respectively. The succinylation of nanoparticles was confirmed by FTIR spectroscopy, and it was possible to elucidate the conversion of amylopectin molecules into amylose blocks. The nanoparticles showed stability during storage in aqueous suspension at 4 °C. By means of the ultrasonic technology, destructuring of the waxy corn starch and, at the same time, the succinylation of the nanoparticles in a total time of 120 min was effectively achieved.

Effect of High-Energy Milling on Bioactive Compounds and Antioxidant Capacity in Nixtamalized Creole Corn Flours.

This study aimed at evaluating the effect of high-energy milling (HEM) and traditional nixtamalization (TN) on bioactive compounds and antioxidant capacity in nixtamalized creole corn flours obtained from a maize genotype cultivated under rainy temporal conditions in the Mexican semidesert. Four creole grains, including San José de Gracia white and blue (WG and BG), Negritas (NG), and Ahualulco white corn grains (SG), were used. For HEM nixtamalization, corn grains were hammer-milled; then, two different conditions were evaluated: treatment H1, with raw flours with 14% moisture content and 1.1% Ca(OH)2, and treatment H2, with raw corn flours with a 23% moisture content and 1.4% Ca(OH)2. The TN process was utilized as a control. TN recorded significant losses in luminosity value L* (p < 0.05), while HEM nixtamalized blue corn flours remained close to -b* values, that is, near to those of raw flour. Anthocyanin content showed higher content values in HEM treatments compared with TN (759.55 and 252.53 mg cyanidin 3-O-ß-D-glucoside (C3G)/kg, respectively) (p < 0.05). Total soluble phenolic content was higher in HEM nixtamalization compared with the traditional process, except for WH2 and SH2 (H2 treatment for WG and SG). Two redundant radical scavenging assays were used: antioxidant capacity (DPPH assay) exhibited less value in nixtamalized flours than in raw flour (p < 0.05). Antioxidant activity by (ABTS) assay was higher in HEM than in TN. Nixtamalized flours produced by HEM demonstrated more improvement in nutraceutical properties than those produced employing TN.

Physico-chemical, thermal, and rheological properties of nixtamalized creole corn flours produced by high-energy milling.

High-energy milling (HEM) was used to produce nixtamalized corn flours, the traditional nixtamalization process was used as a control. Four creole grains were stone-milled, adjusted to an appropriate moisture content and calcium hydroxide concentration and milled using HEM. The physicochemical, thermal, and rheological characteristics of the flours and corn masas were affected by the HEM process. Negritas and Ahualulco creole grains nixtamalized by HEM showed similar viscosity profiles as a control. HEM reduced the gelatinization enthalpy compared to control and raw flours. Diffractograms showed changes in the crystalline structures and FT-IR demonstrated different regions for lipids, proteins, and carbohydrates in all control and treated grains. The texture of corn masas revealed significant differences according to the grain type. ESEM analysis showed smaller particles of HEM flours compared to those of the control. HEM could be a faster, non-pollutant, energy-saving, alternative nixtamalization process.

Physicochemical, thermal, and rheological properties of nixtamalized blue-corn flours and masas added with huitlacoche (Ustilago maydis) paste.

The aim of this work was to evaluate the effect of the addition of huitlacoche paste to nixtamalized blue-corn flours (NBCF) on the physicochemical, thermal, and rheological properties of masas. Raw blue maize was nixtamalized (hydrothermal alkalinized process), then was wet-milled in a stone mill, masa was dehydrated, pulverized and sieved to obtain NBCF; commercial nixtamalized blue-corn flour (CNBCF) was used as a control. Huitlacoche paste in concentrations of 3, 6, 9, 12, 15, and 18% was added to nixtamalized flours. Characteristics of the blue grain showed its great effects on water absorption, viscosity, and masa cohesiveness; the addition of huitlacoche significantly influenced adhesiveness, water-absorption, color, and the rheological properties (p < 0.05). Values between 0.03 and 0.083 kg-force resulted in masas with optimal adhesiveness. The inclusion of huitlacoche paste can be achieved with a maximal addition of 9% in NBCF for an industrial process and could comprise a new industrialization alternative.

Encapsulation and pigmenting potential of betalains of pitaya (Stenocereus pruinosus) fruit.

Betalains of pitaya (Stenocereus pruinosus) fruit can be used as natural pigment, but they are susceptible to deterioration by temperature, pH, and presence of sugars. In this work, a refined extract (Er) of betalains was obtained through aqueous two-phase extraction, which reduced significantly sugar and mucilage contents. In order to favor stability, the encapsulation of the refined extract was evaluated, with native potato starch that was modified through phosphorylation or succinylation and reactive extrusion. Starches were evaluated in terms of degree of substitution, Fourier transform infrared spectroscopy, scanning electron microscopy, and viscous behavior. Microcapsules were formed by spray drying and their stability was evaluated at 40 °C for 39 days and by using them as pigmenting agent of yogurt at 4 °C during 32 days. The behavior of modified starches during encapsulation was superior to that of commercial N-Lok® starch. Microcapsules based on modified starches showed better pigmenting potential and higher stability than Er and microcapsules based on N-Lok® starch. The separation of betalains from pitaya fruit may be a good alternative for adding value to this plant genetic resource.

Preparation and characterization of octenyl succinylated normal and waxy starches of maize as encapsulating agents for anthocyanins by spray-drying.

The encapsulation by spray drying of maize anthocyanins was evaluated using two types of wall materials, consisting of normal and waxy maize starch, which were esterified with octenyl succinic anhydride. The X-ray diffraction analysis revealed that SWMS possessed a completely amorphous, while SNMS had a crystalline structure. SNMS showed peaks at 2θ = 13.1°, 19.8° and 22.4°. The results revealed that SNMS and SWMS had almost the same encapsulation productivity (EP); SNMS showed the best performance because its EP was higher (95%) than in SWMS (90%). The stability of microcapsules produced with SNMS showed the highest anthocyanin retention after storage in the water activity (aw) range of 0.11-0.94 at 40 °C.

Optimization of Extrusion Process of Directly Expanded Snacks Based on Potato Starch in a Single Step for the Formation of Type IV Resistant Starch.

Resistant starch type IV (RSIV) can be produced by chemical modifications (etherized or esterified) such as conversion, substitution, or cross-linking, which can prevent its digestion by blocking enzyme access and forming atypical linkages. In this research, the effects of barrel temperature (145.86-174.14 °C), the screw speed (42.93-57.07 Hz) and derivatization (esterification) in the formation of RSIV content of directly expanded snacks (second generation snacks) were studied. Potato starch was chemically modified by phosphorylation and succinylation, and expanded by using the extrusion cooking process. Snacks with phosphorylated starch showed expansion index from 2.57 to 3.23, bulk density from 306.19 to 479.00 kg/m3 and RSIV from 43.27 to 55.81%. Snacks with succinylated starch had expansion index from 3.52 to 3.82, bulk density from 99.85 to 134.51 kg/m3 and RSIV from 23.17 to 35.01%. The results found in this work showed that it is possible to manufacture extruded directly expanded snacks (second-generation snacks) such as a ready-to-eat (RTE) with good physicochemical properties and without substantial loss of extrusion functionality, which could bring a healthy benefit due to the presence of RSIV.

Physicochemical and Microstructural Characterization of Corn Starch Edible Films Obtained by a Combination of Extrusion Technology and Casting Technique.

Starch edible films (EFs) have been widely studied due to their potential in food preservation; however, their application is limited because of their poor mechanical and barrier properties. Because of that, the aim of this work was to use the extrusion technology (Ex T) as a pretreatment of casting technique to change the starch structure in order to obtain EFs with improved physicochemical properties. To this, corn starch and a mixture of plasticizers (sorbitol and glycerol, in different ratios) were processed in a twin screw extruder to generate the starch modification and subsequently casting technique was used for EFs formation. The best conditions of the Ex T and plasticizers concentration were obtained using response surface methodology. All the response variables evaluated, were affected significatively by the Plasticizers Ratio (Sorbitol:Glycerol) (PR (S:G)) and Extrusion Temperature (ET), while the Screw Speed (SS) did not show significant effect on any of these variables. The optimization study showed that the appropriate conditions to obtain EFs with the best mechanical and barrier properties were ET = 89 °C, SS = 66 rpm and PR (S:G) = 79.7:20.3. Once the best conditions were obtained, the optimal treatment was characterized according to its microstructural properties (X-ray diffraction, Scanning Electron Microscopy and Atomic Force Microscopy) to determine the damage caused in the starch during Ex T and casting technique. In conclusion, with the combination of Ex T and casting technique were obtained EFs with greater breaking strength and deformation, as well as lower water vapor permeability than those reported in the literature.

Effect of Malting and Nixtamalization Processes on the Physicochemical Properties of Instant Extruded Corn Flour and Tortilla Quality.

This research aimed to prepare instant flour from malted and raw (un-malted) corn flours nixtamalized by the extrusion process and evaluate the effect on the physicochemical properties of tortillas prepared using these flours. White maize was malted for 24 h, dried at 50 ± 1 °C, and ground. Subsequently, 0.3 % lime and 25 or 30 % water were added to ground malted or un-malted corn, and the mixture was refrigerated (4 °C) for 12 h. These samples were nixtamalized by an extrusion process in a single screw extruder at two temperature profiles within four heating zones, TP1 (60, 60, 70, and 80 °C) and TP2 (60, 70, 80, and 90 °C), to obtain corn flour. Water was added to the extruded corn flours to make a dough, or masa, and the masa was then molded and baked to obtain tortillas. The corn flours were characterized according to their ability to absorb water and viscosity profile (RVA). The firmness and rollability after 2 and 24 h of storage were determined, and a sensory evaluation was conducted. The malted corn flour extruded with a 25 % moisture content and TP2 temperature profile yielded tortillas with the best firmness and rollability. In conclusion, the changes during the malting of corn grain and the nixtamalization by the extrusion process improved the water absorption capacity of flours and textural properties of the tortilla and produced a product with acceptable sensory properties.

Effect of different calcium sources on the bioactive compounds stability of extruded and nixtamalized blue maize flours.

The stability of antioxidants in extruded and nixtamalized blue maize flours with calcium hydroxide [Ca(OH)2] and calcium lactate [C6H10O6Ca] were evaluated. Extruded blue maize flours batches were obtained by mixing blue maize flours separately with different Ca(OH)2 (0.1, 0.2 and 0.3 %) and C6H10O6Ca (0.3, 0.6 and 0.9 %) concentrations respectively and extruded to obtain the extruded flours. For nixtamalized flours, the maize grains were cooked at 1 % Ca(OH)2 and 2.95 % C6H10O6Ca concentrations respectively. Color, antioxidant activity, total phenolics, total anthocyanins and individual anthocyanins, contents were analyzed. Color, antioxidant activity, anthocyanins contents and total phenolics decreased as the calcium hydroxide concentration increased. In contrast, increasing the calcium lactate concentration on the extruded flours had the opposite effect. The extrusion process retained 57-47 %, 72-62 % and 79-65 % of the anthocyanins content, total phenolic content and antioxidant activity, respectively. These retention rates were higher than those of the nixtamalized flours using the same calcium sources. Cyanidin-3-glucoside and pelargonidin-3-glucoside were identified in the maize kernel and flours. Cyanidin-3-glucoside concentration was increased by both extrusion and nixtamalization processed with either of the two calcium sources. In contrast, pelargonidin-3-glucoside concentration decreased by both processes. Other anthocyanins were observed, but they were not identified.