The effects of extruded endogenous starch on the processing properties of gluten-free Tartary buckwheat noodles

Effects of different extrusion temperatures on the physicochemical properties, edible quality and digestive attributes of multigrain reconstituted rice

Multigrain reconstituted rice, as a nutritious and convenient staple, holds considerable promise for the food industry. Furthermore, highland barley, corn, and other coarse cereals are distinguished by their low glycemic index (GI), rendering them effective in mitigating postprandial blood glucose levels, thereby underscoring their beneficial physiological impact. This study investigated the impact of extrusion temperature on the physicochemical properties, edible quality, and digestibility of multigrain reconstituted rice. The morphology revealed that starch particles that are not fully gelatinized in multigrain reconstituted rice are observed at an extrusion temperature range of 60 °C-90 °C. As the extrusion temperature increased, the degree of gelatinization (DG) increased, while the contents of water, protein, total starch, and amylopectin decreased substantially. Concurrently, the relative crystallinity, orderliness of starch, and heat absorption enthalpy (ΔH) decreased significantly, and water absorption (WAI) and water solubility (WSI) increased markedly. Regarding edible quality, sensory evaluation displayed an initial increase followed by a decrease. In terms of digestibility, the estimated glycemic index (eGI) increased from 61.10 to 70.81, and the GI increased from 60.41 to 75.33. In addition, the DG was significantly correlated with both eGI (r = 0.886**) and GI (r = 0.947**). The results indicated that the ideal extrusion temperature for multigrain reconstituted rice was 90 °C. The findings underscored the pivotal role of optimal extrusion temperatures in the production of multigrain reconstituted rice, which features low GI and high nutritional quality.

Effect of starch degradation induced by extruded pregelatinization treatment on the quality of gluten-free brown rice bread

There is considerable interest in preparing high-quality gluten-free bread. The effect of the molecular structure of extruded pregelatinization starch on the dough's rheological properties and the brown rice bread's quality was investigated. Extruded rice starch (ERS) was prepared with various added moisture contents of 20 % (ERS20), 30 % (ERS30), and 40 % (ERS40), respectively. ERS had smaller molecular weight and more short branched chains as the moisture content decreased. The dough elasticity and deformation resistance were improved with the ERS supplementation and in the order of ERS40 > ERS30 > ERS20 at the same level. Fortification with ERS improved the gluten-free brown rice bread quality. Compared to the control group, breadcrumbs supplemented with ERS20 at the 10 % level showed an increase in cell density from 17.87 cm-2 to 28.32 cm-2, a decrease in mean cell size from 1.22 mm2 to 0.81 mm2, and no significant change in cell area fraction. In addition, the specific volume increased from 1.50 cm3/g to 2.04 cm3/g, the hardness decreased from 14.34 N to 6.28 N, and the springiness increased from 0.56 to 0.74. The addition of extruded pregelatinization starches with smaller molecular weights and higher proportions of short chains is promising for preparing high-quality gluten-free bread.

Influence of enzymatic modification on the basis of improved extrusion cooking technology (IECT) on the structure and properties of corn starch

Enzymatic modification can directly affect the structure and properties of starch, but generally causes high energy consumption in drying process. Improved extrusion cooking technology (IECT) itself is a starch modification technology. In this work, a co-extrusion method of starch with 42 % moisture and enzyme was adopted to reveal the effects of different enzyme dosages on the structure and properties of corn starch. After enzyme treatment on the basis of IECT, starch granules were broken into fragments without the occurrence of clear Maltese cross. R1047/1022 and R995/1022 values, peak intensity of Raman spectra and gelatinization temperature decreased, and the full width at half maximum at 480 cm-1 of Raman spectra raised. Moreover, the bound water proportion decreased from 87.44 % to 85.84 % ∼ 78.67 %, and the maximum light transmittance and dextrose equivalent values increased to 34.13 % and 26.14, respectively. The solubility of starch granules was all above 60 %. Findings supported that the mechanochemical effect of IECT on starch was conducive to the enzymatic modification.

Effect of improved extrusion cooking technology (IECT) on structure, physical properties and in vitro digestibility of starch

Extrusion can modify the structure and physical properties of starch, while the extent of improved extrusion cooking technology (IECT) affects the starch with high moisture content and different crystal types remaining unclear. Therefore, the influence of IECT at different screw speeds on the structure, physical properties and in vitro digestibility of corn (A-type), potato (B-type) and pea (C-type) starches with high moisture content (42 %) was explored. Results indicated that IECT treatment caused similar variations on structure, physical properties, and in vitro digestibility of the 3 types of starches. The contents of slowly digestible starch (SDS) and resistant starch (RS) decreased by IECT treatment, accompanied by a reduction of crystallinity, enthalpy of gelatinization, gelatinization temperature and viscosity, while the content of rapidly digestible starch (RDS) and the ratio of bound water increased. And the changes in in vitro digestibility of starch were closely related to the damage to starch structure caused by IECT. Furthermore, most of starch granules were in the agglomeration stage by appropriate IECT treatment, which induced the exposure of a great quantity of enzyme binding sites to enhance the in vitro digestibility.

Effect of sodium carbonate on the properties of seventy percent of Tartary buckwheat composite flour-based doughs and noodles and the underlying mechanism

The impact of Na2 CO3 on the properties of doughs and noodles containing 70% Tartary buckwheat flour was investigated. Low-field 1 H nuclear magnetic resonance showed the mobility of water in the doughs significantly declined with the addition content of alkali from 0% to 0.9%. Na2 CO3 promoted the transformation from free sulfhydryl groups to disulfide bonds in doughs because the sulfhydryl groups in cysteine preferred to form thiolate anion and then oxidate under alkaline conditions. As for non-covalent chemical interactions, a significant increase of hydrogen bonds and a decrease of hydrophobic interactions were observed after Na2 CO3 addition. Quantitative analysis of microstructure showed that more uniform and denser gluten networks with higher branching rate and shorter average protein length and width formed in the doughs with 0.3%-0.6% of Na2 CO3 . The aggregated glutenin macropolymer and enhanced protein structure led to significantly stronger tensile of Tartary buckwheat dough sheets, which could meet the demand of continuous processing in the factory. Dough with alkali had higher swelling power and pasting viscosities, contributing to higher water absorption, and improved textural attributes of cooked noodles. This study demonstrated the possibility of adding Na2 CO3 at a moderate level for promoting the sheeting, cooking, and eating properties of high Tartary buckwheat flour composite noodles.

Enhancing the quality of steamed oat cake by partially gelatinized starch in oat flour and its molecular mechanism

The aim of this study was to investigate the effect and mechanism of partially gelatinized starch in oat flour on the rheological characteristics of the oat batter and the quality of steamed oat cakes. The results showed that an increase in the gelatinization degree of oat flour destroyed the starch granular structure and the long-range molecular order of starch, accompanied by a decrease of crystallinity from 22.28 % to 8.72 % and the formation of a starch-lipid complex. The increased gelatinization degree of oat flour destroyed the protein network and promoted the formation of the starch gel network in oat batter. Meanwhile, the addition of gelatinized oat flour enhanced the elastic behavior of the oat batter and the gas retention ability of the fermented oat batter, while decreased the total gas volume from 1075.5 mL to 827.0 mL. The steamed oat cake containing 50 % gelatinization degree of oat flour (G50) showed moderate hardness, springiness and chewiness, as well as the largest cell area fraction (37.35 %), due to the formation of a dense starch gel-protein double network and the enhancement of long/short-range molecular order of starch. Thus, this study provided the feasibility of improving the quality of oat-based fermented products by changing the gelatinization degree of oat starch.

Impact of okara on quality and in vitro starch digestibility of noodles: The view based on physicochemical and structural properties

The development of cereal foods with slow starch digestibility is important for the general improvement of human health. In this study, the quality properties of noodles with added okara, in vitro starch digestibility, and the underlying mechanisms of the influence of okara on noodles were studied. Low concentrations (5 and 10 %) of okara improved the texture, cooking, and sensory properties of the noodles. Okara decreased the rapidly digestible starch (RDS) content, increased the resistant starch (RS) content, and reduced the predicted glycaemic index (pGI) of noodles. The pasting viscosity, thermal stability, and dynamic rheological results indicated that okara improved the starch crystallite stability of wheat flour and viscoelasticity of dough. Moreover, Fourier transform infrared (FTIR) spectroscopy showed that okara promoted the formation of starch-lipid complexes and improved the short-range structural order of starch. Additionally, microstructure imaging and protein network analysis (PNA) indicated that low addition of okara promoted the compactness of the okara-gluten-starch matrix, thus reducing the contact between starch and hydrolytic enzymes. These results reveal the effect of okara on the quality properties and starch digestibility in a starch-gluten complex system.

Effects of primary, secondary and tertiary structures on functional properties of thermoplastic starch biopolymer blend films

To better understand the correlation between structure and properties in thermoplastic starch biopolymer blend films, the effects of amylose content, chain length distribution of amylopectin and molecular orientation of thermoplastic sweet potato starch (TSPS) and thermoplastic pea starch (TPES) on microstructure and functional properties of thermoplastic starch biopolymer blend films were studied. After thermoplastic extrusion, the amylose contents of TSPS and TPES decreased by 16.10 % and 13.13 %, respectively. The proportion of the chains with the degree of polymerization between 9 and 24 of amylopectin in TSPS and TPES increased from 67.61 % to 69.50 %, and from 69.51 % to 71.06 %, respectively. As a result, the degree of crystallinity and molecular orientation of TSPS and TPES films increased as compared to sweet potato starch and pea starch films. The thermoplastic starch biopolymer blend films possessed a more homogeneous and compacter network. The tensile strength and water resistance of thermoplastic starch biopolymer blend films increased significantly, whereas thickness and elongation at break of thermoplastic starch biopolymer blend films decreased significantly.

Starch-based noodles: Current technologies, properties, and challenges

Starch noodles are gaining interest due to the massive popularity of gluten-free foods. Modified starch is generally used for noodle production due to the functional limitations of native starches. Raw materials, methods, key processing steps, additives, cooking, and textural properties determine the quality of starch noodles. The introduction of traditional, novel, and natural chemical additives used in starch noodles and their potential effects also impacts noodle quality. This review summarizes the current knowledge of the native and modified starch as raw materials and key processing steps for the production of starch noodles. Further, this article aimed to comprehensively collate some of the vital information published on the thermal, pasting, cooking, and textural properties of starch noodles. Technological, nutritional, and sensory challenges during the development of starch noodles are well discussed. Due to the increasing demands of consumers for safe food items with a long shelf life, the development of starch noodles and other convenience food products has increased. Also, the incorporation of modified starches overcomes the shortcomings of native starches, such as lack of viscosity and thickening power, retrogradation characteristics, or hydrophobicity. Starch can improve the stability of the dough structure but reduces the strength and resistance to deformation of the dough. Some technological, sensory, and nutritional challenges also impact the production process.

Characterization of gallic acid-Chinese yam starch biodegradable film incorporated with chitosan for potential use in pork preservation

The widely use of petroleum-based plastics causes serious environmental pollution and oil resource shortage. In this work, biodegradable films were prepared based on gallic acid (GA)-induced Chinese yam starch (YS) and chitosan (CS). The fresh-keeping effect of biodegradable films on the pork meat preservation were investigated. The prepared GA/YS/CS biodegradable films exhibited thinner thickness and better light transmittance, because CS effectively decreased the viscosity of film-forming solution and weaken its internal link structure. The SEM results and mechanical results revealed that the YS, GA, and CS had a good compatibility, GA modification and adding CS markedly improved the tensile strength of YS-based film, because the interaction between CS and starch molecular was facilitate owing to the NH₃⁺ of CS tended to form hydrogen bonds with the hydroxyl group of starch. Sensory analysis results suggested that GA/YS/CS films can effectively improve the quality of pork during storage compared to the package of polyethylene film. In summary, the prepared GA/YS/CS film in this work had practical application potential in pork preservation due to its excellent mechanical, antibacterial, oxidation resistance properties, and the development and application of biodegradable starch film can greatly reduce the increasingly serious environmental pollution pressure.

Effect of Frozen Treatment on the Sensory and Functional Quality of Extruded Fresh Noodles Made from Whole Tartary Buckwheat

Extruded noodles made from whole Tartary buckwheat are widely known as healthy staple foods, while the treatment of fresh noodles after extrusion is crucial. The difference in sensory and functional quality between frozen noodles (FTBN) and hot air-dried noodles (DTBN) was investigated in this study. The results showed a shorter optimum cooking time (FTBN of 7 min vs. DTBN of 17 min), higher hardness (8656.99 g vs. 5502.98 g), and less cooking loss (5.85% vs. 21.88%) of noodles treated by freezing rather than hot air drying, which corresponded to better sensory quality (an overall acceptance of 7.90 points vs. 5.20 points). These effects on FTBN were attributed to its higher ratio of bound water than DTBN based on the Low-Field Nuclear Magnetic Resonance results and more pores of internal structure in noodles based on the Scanning Electron Microscopy results. The uniform water distribution in FTBN promoted a higher recrystallization (relative crystallinity of FTBN 26.47% vs. DTBN 16.48%) and retrogradation (degree of retrogradation of FTBN 34.67% vs. DTBN 26.98%) of starch than DTBN, strengthening the stability of starch gel after noodle extrusion. FTBN also avoided the loss of flavonoids and retained better antioxidant capacity than DTBN. Therefore, frozen treatment is feasible to maintain the same quality as freshly extruded noodles made from whole Tartary buckwheat. It displays significant commercial potential for gluten-free noodle production to maximize the health benefit of the whole grain, as well as economic benefits since it also meets the sensory quality requirements of consumers.

Effect of Tartary Buckwheat Bran Substitution on the Quality, Bioactive Compounds Content, and In Vitro Starch Digestibility of Tartary Buckwheat Dried Noodles

This study aimed to investigate the impact of partial replacement of Tartary buckwheat flour (TBF) with Tartary buckwheat bran flour (TBBF) on the quality, bioactive compounds content, and in vitro starch digestibility of Tartary buckwheat dried noodles (TBDNs). When the substitution of TBBF was increased from 0 to 35%, the cooking and textural properties decreased significantly (p < 0.05), while the content of bioactive compounds (phenolic, flavonoids and dietary fiber) increased significantly (p < 0.05). In addition, the substitution of TBBF decreased the starch digestibility of TBDNs. A 10.4% reduction in eGI values was observed in the TBDNs with 35% TBBF substitution compared to the control sample. The results of differential scanning calorimetry showed that with the increase of TBBF, TBDNs starch became more resistant to thermal processing. Meanwhile, the X-ray diffraction and Fourier transform infrared spectroscopy results revealed that the long- and short-range ordered structures of TBDN starch increased significantly (p < 0.05). Furthermore, the substitution of TBBF decreased the fluorescence intensity of α-amylase and amyloglucosidase. This study suggests that replacing TBF with TBBF could produce low glycemic index and nutrient-rich TBDNs.

A review of extrusion-modified underutilized cereal flour: chemical composition, functionality, and its modulation on starchy food quality

Compared with three major cereals, underutilized cereals (UCs) are those with less use but having abundant bioactive components and better functionalities after proper processing. As a productive and energy-efficient technology, extrusion has been used for UC modification to improve its technological and nutritional quality. Extrusion could induce structural and quantitative changes in chemical components of UC flour, the degree of which is affected by extrusion intensity. Based on the predominant component (starch), functionalities of extruded underutilized cereal flour (EUCF) and potential mechanisms are reviewed. Considering bioactive compounds, it also summarizes the physiological functions of EUCF. EUCF incorporation could modulate the dough rheological behavior and starchy foods quality. Controlling extrusion intensity or incorporation level of EUCF is vital to achieve sensory-appealing and nutritious products. This paper gives comprehensive information of EUCF to promote its utilization in novel staple foods.

Influence of the Addition of Extruded Endogenous Tartary Buckwheat Starch on Processing and Quality of Gluten-Free Noodles

Extruded starch could be used as a thickener for food processing due to its pre-gel properties. This study aimed to explore the influence of the addition of extruded endogenous Tartary buckwheat starch (ES) on the process and quality of gluten-free noodles. ES was mixed with Tartary buckwheat flour in different proportions (10–40%) to prepare the blended flour and noodles. When the content of ES was increased, the swelling power of blended flour at 90 °C had no significant changes, and the decrease in peak viscosity of blended flour was reduced. This indicated that the high-content ES could afford better thermal stability for blended flour and inhibit the swelling ability. The higher level of ES was beneficial to the formation and stabilization of dough, and the improvement of noodle tensile strength. Furthermore, there was no difference in cooking loss between noodles with 30% and 40% ES addition. The microstructure and water distribution of the noodles prepared by blended flour indicated that the gel-entrapped structure organized by the higher content ES could be closely related to the above results. In conclusion, higher ES could contribute to improving the processing properties and quality of noodles.