Effects of flour dynamic viscosity on the quality properties of buckwheat noodles

High moisture extrusion induced interaction of Tartary buckwheat protein and starch mitigating the in vitro starch digestion

This study investigated the effects of adding 4-20 % Tartary buckwheat protein (TBP, with a purity of 93.35 %) on the structural, thermal, and digestive properties of Tartary buckwheat starch (TBS) by high moisture (60 %) extrusion. The added TBP embedded and enwrapped the starch matrix, which formed protein-starch complexes. After adding 4 %-20 % TBP, the shear degradation of AP decreased. Conversely, the shear degradation of AM chains increased. The addition of TBP promoted the retrogradation of starch in extrudates, enhancing their short- and long-range ordered structures. Compared with extruded TBS, extrudates contained TBP showed a reduction of gelatinization enthalpy, a high content of resistant starch, and a lower starch digestibility. These findings provided an insight into the protein-starch interactions under high moisture extrusion, which would promote the advancement of starch-based foods with high TBP content.

Effects of different adzuki bean flour additions on structural and functional characteristics of extruded buckwheat noodles

BACKGROUND

Understanding the effects of different additions of adzuki bean flour (ABF) on structural and functional characteristics of extruded buckwheat noodles is important in developing high-quality starchy foods with desirable glycemic indexes. This study explored how varying amounts of ABF in extruded buckwheat noodles influenced their structural and functional characteristics.

RESULTS

The findings indicated that adding ABF substantially boosted the levels of protein and flavonoids, while decreasing the content of fat and starch. Adding ABF to the noodles extended the optimum cooking time and led to a reduction in both the stickiness of the cooked noodles and the pore size of the starch gel structure, compared with pure buckwheat noodles. Fourier transform infrared spectroscopy indicated that R1047/1022 increased with the content of ABF increased, while R1022/995 decreased. X-ray diffraction showed that the relative crystallinity of buckwheat noodles was enhanced with increasing ABF amount. Adding ABF notably significantly decreased the estimated glycemic index. The buckwheat noodles extruded with 20% ABF addition demonstrated notably stronger α-glucosidase inhibitory effects than those extruded with no ABF addition.

CONCLUSION

The present study demonstrates that the additions of ABF improved the structure and hypoglycemic activity of extruded buckwheat noodles while decreasing starch digestibility, and the optimal value was reached at an ABF addition of 20%. The study might fill gaps in starch noodle research and provide a new strategy for the development of functional food in the food industry. © 2024 Society of Chemical Industry.

The mechanisms of thermal processing techniques on modifying structural, functional and flour-processing properties of whole-grain highland barley

The mechanisms underlying three thermal processing methods, namely hot-air drying, microwave irradiation, and heat fluidization, were systematically investigated to evaluate their effects on the structural, functional, and flour-processing properties of whole-grain highland barley. Starch granules were partially damaged when treated with hot-air drying and microwave irradiation. However, these granules were predominantly aggregated or encapsulated in proteins following heat fluidization. Accordingly, flour produced through heat fluidization exhibited the lowest relative crystallinity of 3.43 % and the greatest α → β shifts in secondary protein structures, compared to other treatments. These structural changes led to improved water/oil holding capacity, enhanced elastic property, reduced enthalpy of 4430 J/kg and breakdown viscosity of 0.24 Pa·s. Moreover, fresh noodles made from heat fluidization-treated highland barley exhibited superior textural features. Overall, heat fluidization could be a more effective method to modify the flour-processing properties of whole highland barley flour and enhance its applicability in the food industry.

Effects of the addition of cassava starch and the size of water clusters on physicochemical and cooking properties of rice noodles

It is meaningful to explore the addition of additives and the structural characteristics of water on the quality of rice noodles. Herein, the effects of the addition of cassava starch and the size of water clusters on physicochemical and cooking properties of rice noodles were systematically studied. The addition of 25 % cassava starch effectively enhanced the swelling performance and textural properties of rice noodles. In comparison to non-activated water with large water clusters (LW), activated water with small water clusters (SW) significantly affected the interaction between water and starch molecules. Compared with LW-RN-25CS (rice noodles made with LW and 25 % cassava starch), SW-RN-25CS (rice noodles made with SW and 25 % cassava starch) presented better textural properties, including hardness, springiness, and adhesiveness. The rehydration time of SW-RN-25CS decreased from 12.31 ± 0.25 min (LW-RN-25CS) to 10.92 ± 0.46 min. This study provides reliable strategy and technology to produce high-quality rice noodles.

Effect of salt and alkali on the viscoelastic behavior of noodle dough sheet with different wheat starch granule sizes

The underlying mechanisms of salt and alkali on the viscoelastic behaviors of noodle dough sheets with varied B/A-type starch ratios were investigated from water state, protein polymerization and conformation, and microstructure. The viscoelastic behaviors of dough sheets increased with increasing B/A-type starch ratio, regardless of the presence of salt and alkali, indicating the addition of salt and alkali did not change the effect law of starch granule size on dough viscoelasticity. The viscoelastic moduli of dough decreased in the presence of salt and alkali, and the effect was more obvious as the ratio of B/A-type starch decreased, which was mainly determined by the interactions of protein-protein, protein-starch, and starch-starch in dough systems. In the low ratio of B/A-type starch dough sheets, NaCl enhanced the non-covalent interactions and β-sheet structure, while alkali promoted the covalent cross-linking of protein. In the high ratio B/A-type starch dough samples, the big starch surface area provided by a high phase volume of starch granules led to the domination of starch-starch interactions over the protein phase, thus determining the viscoelastic behavior of dough. SEM images showed that NaCl caused the gluten to form a fibrous structure, while alkali induced a membrane-like and more closed structure. NaCl and alkali showed different influences on water distribution, molecular conformation, and network structure of dough sheets with varied B/A-type starch ratios and thus contributed to the different viscoelastic behaviors.

Effect of twin-screw extrusion pretreatment on starch structure, rheological properties and 3D printing accuracy of whole potato flour and its application in dysphagia diets

Twin-screw extrusion pretreatment has great potential for the development of three-dimensional (3D) printed food as dysphagia diets. This study aimed to investigate the effect of twin-screw extrusion pretreatment on starch structure, rheological properties and 3D printing accuracy of whole potato flour and its application in dysphagia diets. The results indicated that twin-screw extrusion pretreatment was found to change chain length distributions, short-range ordered structure and relative crystallinity of whole potato flour (WPF), thereby improving its 3D printing performance. With the increasing proportion of long linear chains (DP > 12), the intensity of hydrogen bonds, linear viscoelastic region, storage modulus (G'), loss modulus (G″), viscosity and n of whole potato flour paste were increased, enhancing high printing accuracy and shape retention of 3D printed samples with a denser microstructure and smaller pore diameter distribution. The whole potato flour paste extruded with a peristaltic pump speed at 5.25 mL/min (WPF-4) displayed the highest printing accuracy with excellent rheological properties, good water distribution state and dense network structure, which classified as class 5 level dysphagia diets. This research provides an effective guidance for the modification of whole potato flour using twin-screw extrusion pretreatment as 3D printed food inks for dysphagia patients.

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.

Effect of starch granule size on the properties of dough and the oil absorption of fried potato crisps

Starch is a key element in fried potato crisps, however, the effect of starch granule size on oil absorption of the product have yet to be fully investigated. The study explored the impact of starch granule size on both the dough characteristics and oil absorption in potato crisps. The dough composed of small-sized potato granules showed more compact and uniform network system. Additionally, X-ray Microscope analysis showed that potato crisps prepared with small-sized potato granules had limited matrix expansion and fewer pores, cracks, and voids. The small-sized potato and small-sized wheat starches granule addition crisps displayed a significantly greater average cell thickness (52.05 and 53.44 μm) than other samples, while exhibiting notably lower average porosity (61.37 % and 60.28 %) compared to other samples. Results revealed that potato crisps with medium and small potato granules had 12.91 % and 21.92 % lower oil content than those containing large potato starch. Potato crisps with B-type wheat starch showed 16.36 % less oil absorption than those with A-type wheat starch. Small-sized starches significantly influence the dough structure and contribute to the reduction of oil absorption in fried products. The generated insights may provide monitoring indexes for cultivating potato varieties with low oil absorption.

A comparative study of magnetic field on the maximum ice crystal formation zone and whole freezing process for improving the frozen dough quality

Magnetic field individually applied on the maximum ice crystal formation zone (MMF) and the whole freezing process (WMF) was compared to improve the quality of multiple freezing-thawing treated dough. All treatments showed that the breadmaking performances of magnetic field-assisted freezing were better than the conventional freezing. Especially, the WMF-treated breads exhibited higher resilience and lower firmness than MMF-treated breads. WMF treatment made dough remained a continuous and compact gluten-starch matrix while the starches and glutens got separated in MMF-treated dough. It could keep the gluten macropolymer from freezing-induced depolymerization with the decreased free sulfhydryl by 7.09% and more ordered secondary structure. WMF had positive effects on the homogeneous water distribution and high water-binding ability in frozen dough where the freezable water decreased from 32.47% to 30.77%. This comparative study of different freezing stages provided new insights into the better application of magnetic field on frozen dough-based food.

Changes in Cooking Characteristics, Structural Properties and Bioactive Components of Wheat Flour Noodles Partially Substituted with Whole-Grain Hulled Tartary Buckwheat Flour

The whole-grain, hulled Tartary buckwheat flour (HTBF) with outstanding bioactive functions was prepared, and the effects of partial substitution ratios (0, 30%, 51% and 70%) of wheat flour with HTBF on the characteristics of TB noodles (TBNs) were investigated, mainly including the cooking characteristics, sensory analysis, internal structure, bioactive components, and in vitro starch digestibility. With an increasing replacement level of HTBF, the water absorption index of the noodles decreased, whereas the cooking loss increased. A sensory analysis indicated that there were no off-flavors in all TBN samples. The scanning electron microscope images presented that the wheat noodles, 30% TBNs and 70% TBNs had dense and uniform cross sections. Meanwhile, the deepest color, V-type complexes, and lowest crystallinity (13.26%) could be observed in the 70% TBNs. A HTBF substitution increased the rutin content and the total phenolic and flavonoid contents in the TBNs, and higher values were found in the 70% TBNs. Furthermore, the lowest rapidly digestible starch content (16%) and highest resistant starch content (66%) were obtained in the 70% TBNs. Results demonstrated that HTBF could be successfully applied to make TBNs, and a 70% substitution level was suggested. This study provides consumers with a good option in the realm of special noodle-type products.

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.

Buckwheat: an underutilized crop with attractive sensory qualities and health benefits

The pseudocereal buckwheat is one of the ancient domesticated crops. The aim of the present review was to outline the potential of buckwheat as an agricultural crop and brings studies on buckwheat into a new larger perspective combining current knowledge in agricultural history and practice, nutritional and sensory properties, as well as possible benefits to human health. Historically, buckwheat was an appreciated crop because of its short growth period, moderate requirements for growth conditions, and high adaptability to adverse environments. Nowadays, interest in buckwheat-based food has increased because of its nutritional composition and many beneficial properties for human health. Buckwheat is a rich course of proteins, dietary fibers, vitamins, minerals, and bioactive compounds, including flavonoids. Moreover, it contains no gluten and can be used in the production of gluten-free foods for individuals diagnosed with celiac disease, non-celiac gluten sensitivity, or wheat protein allergies. Buckwheat is traditionally used in the production of various foods and can be successfully incorporated into various new food formulations with positive effects on their nutritional value and attractive sensory properties. Further research is needed to optimize buckwheat-based food development and understand the mechanism of the health effects of buckwheat consumption on human well-being.

Starch granules and their size distribution in wheat: Biosynthesis, physicochemical properties and their effect on flour-based food systems

Starch is a vital component of wheat grain and flour, characterized by two distinct granule types: A-type starch (AS) with granules larger than 10 µm in diameter, and B-type starch (BS) with granules measuring no more than 10 µm in diameter. This review comprehensively evaluates the isolation, purification, and biosynthesis processes of these types of granules. In addition, a comparative analysis of the structure and properties of AS and BS is presented, encompassing chemical composition, molecular, crystalline and morphological structures, gelatinization, pasting and digestive properties. The variation in size distribution of granules leads to differences in physicochemical properties of starch, influencing the formation of polymeric proteins, secondary and micro-structures of gluten, chemical and physical interactions between gluten and starch, and water absorption and water status in dough system. Thus, starch size distribution affects the quality of dough and final products. In this review, we summarize the up-to-date knowledge of AS and BS, and propose the possible strategies to enhance wheat yield and quality through coordinated breeding efforts. This review serves as a valuable reference for future advancements in wheat breeding.

Impact of exopolysaccharides-producing lactic acid bacteria on the chemical, rheological properties of buckwheat sourdough and the quality of buckwheat bread

Exopolysaccharides (EPS) produced in situ by lactic acid bacteria (LAB) during sourdough fermentation have the potential to replace hydrocolloids in gluten-free sourdoughs. This study investigated effects of an EPS-producing Weissella cibaria NC516.11 fermentation on chemical, rheological properties of sourdough and the quality of buckwheat bread. Results indicate that the buckwheat sourdough fermentation by W. cibaria NC516.11 had lower pH (4.47) and higher total titrable acidity (8.36 mL) compared with other groups, and the polysaccharide content reached 3.10 ± 0.16 g/kg. W. cibaria NC516.11 can significantly improve the rheological properties and viscoelastic properties of sourdough. Compared with control group, the baking loss of NC516.11 group bread decreased by 19.94%, specific volume increased by 26.03%, and showed good appearance and cross-sectional morphology. Scanning electron micrograph revealed an intact and less porous cell structure. Meanwhile, W. cibaria NC516.11 significantly improved the texture of the bread and reduced the hardness and moisture loss during storage.

Optimization of freezing methods and composition of frozen rice dough reconstituted by glutinous rice starch and gluten

This study investigated the effects of four different freezing methods on the texture of rice dough reconstituted by glutinous rice starch and gluten, and the changes of properties of rice dough with different gluten ratios after liquid nitrogen (LF) treatment. The profiles of frozen rice dough were studied by texture analyzer, low-field NMR, SEM, FT-IR, DSC, CLSM, X-RD and RVA. Results revealed that with the slowing down of freezing rate, the damage of freezing process to starch granules and protein structure in frozen rice dough increases, resulting in the increase of damaged starch, the decrease of protein ordered structure, the change of bound water in frozen rice dough to free water, the decrease of frozen rice dough hardness and elasticity, the decrease of storage modulus (G') and the deterioration of frozen rice dough texture. The addition of gluten in frozen rice dough will increase the short-range ordered structure and crystal structure of starch, reduce the digestibility of starch, and change the viscosity characteristics of frozen rice dough. Based on the experimental results, adding 10 % gluten is more suitable for making frozen rice dough, while LF has the least effect on frozen rice dough texture.

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.

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.

Phenolic Release during In Vitro Digestion of Cold and Hot Extruded Noodles Supplemented with Starch and Phenolic Extracts

Dietary phenolic compounds must be released from the food matrix in the gastrointestinal tract to play a bioactive role, the release of which is interfered with by food structure. The release of phenolics (unbound and bound) of cold and hot extruded noodles enriched with phenolics (2.0%) during simulated in vitro gastrointestinal digestion was investigated. Bound phenolic content and X-ray diffraction (XRD) analysis were utilized to characterize the intensity and manner of starch-phenolic complexation during the preparation of extruded noodles. Hot extrusion induced the formation of more complexes, especially the V-type inclusion complexes, with a higher proportion of bound phenolics than cold extrusion, contributing to a more controlled release of phenolics along with slower starch digestion. For instance, during simulated small intestinal digestion, less unbound phenolics (59.4%) were released from hot extruded phenolic-enhanced noodles than from the corresponding cold extruded noodles (68.2%). This is similar to the release behavior of bound phenolics, that cold extruded noodles released more bound phenolics (56.5%) than hot extruded noodles (41.9%). For noodles extruded with rutin, the release of unbound rutin from hot extruded noodles and cold extruded noodles was 63.6% and 79.0%, respectively, in the small intestine phase, and bound rutin was released at a much lower amount from the hot extruded noodles (55.8%) than from the cold extruded noodles (89.7%). Hot extrusion may allow more potential bioaccessible phenolics (such as rutin), further improving the development of starchy foods enriched with controlled phenolics.

Effects of Jet Milling on the Physicochemical Properties of Buckwheat Flour and the Quality Characteristics of Extruded Whole Buckwheat Noodles

The effects of jet milling on the physicochemical properties of buckwheat flour and the quality characteristics of extruded whole buckwheat noodles (WBN) were investigated in this study. The results reveal that the application of jet milling significantly reduced the particle size of buckwheat flour. As a result, the damaged starch content, water solubility index, water absorption index and swelling power of buckwheat flour all increased. It was worth noting that moderately ground buckwheat flour powder (D₅₀ = 65.86 μm) had the highest pasting viscosity and gel hardness. The breaking rate and cooking loss of extruded whole buckwheat noodles made from the above powder were reduced by 33% and 16%, respectively. Meanwhile, they possessed the highest lightness and firmest network structure. Jet milling increased the soluble dietary fiber (SDF) content from 3.45% to 4.39%, and SDF further increased to 5.28% after noodle extrusion. This study was expected to provide a reference for exploiting high-quality gluten-free noodles from the perspective of milling.

Rheological, microstructure and mixing behaviors of frozen dough reconstituted by wheat starch and gluten

The effects of starch and gluten on the physicochemical properties of frozen dough were studied using reconstituted flour. The profiles of frozen dough were studied by Mixolab, rheometer, scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). Results revealed that starch, rather than gluten, played a decisive role in mixing properties. The breakdown and aggregation of the gluten network structure as well as the formation of β-turns and β-sheets in the frozen dough would be aggravated by the freezing of wheat starch. Smaller wheat starch granules (B-Type granules) affected the secondary structure of gluten network more than larger granules (A-Type granules), resulting in greater rheological property changes. The viscoelastic properties and freezable water content of frozen dough were more influenced by the freezing of gluten.

Effect of Frying Process on Nutritional Property, Physicochemical Quality, and in vitro Digestibility of Commercial Instant Noodles

The effects of frying process on the nutritional property, physicochemical quality, and in vitro digestibility of instant noodle products are investigated in this study. Scanning electron microscope (SEM) and Fourier transform infrared spectrometer (FT-IR) were also used to explore the changes in the microstructure and protein transformation. Noodles, after the frying process, showed a lower proportion of carbohydrate, protein, fiber, and also total starch and digestible starch, but higher content of fat and resistant starch in the proximate analysis. The frying process was also considered to improve the texture, surface color, and sensory properties of instant noodle products, accompanied by better cooking quality, including shorter cooking time and lower cooking loss during the rehydration. The honeycomb-like, porous, and less uniformed structure, and also the higher levels of β-sheets and β-turns, and the lower proportion of α-helixes of protein structure from fried instant noodle was also observed. The in vitro digestibility of starch and protein were downregulated in the fried group (81.96% and 81.31, respectively, on average) compared with the non-fried group (97.58% and 88.78, respectively, on average). Thus, the frying process lowered the glycemic index and regulated protein secondary structure by inhibiting continuous digesting enzyme activity, generating starch-lipid complexes, and changing the levels of protein transformation. In conclusion, our findings will provide an innovative evaluation of the frying process on instant noodles and even other various starch-based prepared food products.

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.

Hydration and plasticization effects of maltodextrin on the structure and cooking quality of extruded whole buckwheat noodles

In order to improve the structure and cooking quality of extruded whole buckwheat noodles (EWBN), maltodextrin (MD), the homologous substances of starch, was added to buckwheat flour to prepare the EWBN. Hydrogen bonds formed between MD and buckwheat starch molecules and the crystallinity of EWBN decreased as determined by FT-IR and X-ray diffraction, which indicated plasticization effects of MD on buckwheat starch. The content of tightly bound water first increased and then decreased with the increasing amount of MD and the cooking time of EWBM decreased from 5.4 to 3.1 min due to the hydration effects of MD. The cooking loss first decreased and then increased, and showed a minimum value of 9.22% when adding 1 wt% of MD. For texture properties, the hardness, stickiness, chewiness and elongation at break of EWBN first increased and then decreased with the addition of MD, and all reached the maximum value at 3 wt% of MD. These findings showed the potential of adding MD, especially at the appropriate concentration, for improving structure and cooking quality of EWBN.

Buckwheat noodles: processing and quality enhancement

In recent years, buckwheat noodles have gained increased importance because of their functional properties. These qualities are attributed to the abundance of bioactive compounds (e.g., rutin, quercetin) and nutraceuticals (e.g., B vitamins, unsaturated fatty acids). Buckwheat noodle consumption has been shown to be associated with improved metabolic health. Buckwheat flour exhibits properties similar to those of common cereal flours in food processing, but devoid of gluten. However, the maintenance of good textural properties and high sensory acceptability are key challenges in the development of gluten-free products, and these limitations prevented widespread application of buckwheat in the food industry. Nevertheless, continuous technological developments related to raw materials processing, noodle processing, and noodle quality enhancement have contributed to the growing popularity and acceptability of buckwheat noodles in recent times. These improvements could render buckwheat noodles a healthy gluten-free alternative to wheat noodles.

Effect of Moisture Distribution Changes Induced by Different Cooking Temperature on Cooking Quality and Texture Properties of Noodles Made from Whole Tartary Buckwheat

While precooking and processing have improved the quality of gluten-free noodles, the effects of different cooking temperatures on their quality—neither gluten-free noodles nor whole Tartary buckwheat noodles—have rarely been clarified. This study investigated the key role of moisture distribution induced by different cooking temperatures in improving the noodle quality of whole Tartary buckwheat. The results showed that cooking temperatures higher than 70 °C led to a sharp increase in cooking loss, flavonoid loss and the rate of broken noodles, as well as a sharp decrease in water absorption. Moreover, the noodles cooked at 70 °C showed the lowest rate of hardness and chewiness and the highest tensile strength of all cooking temperatures from 20 °C to 110 °C. The main positive attribute of noodles cooked at 70 °C might be their high uniform moisture distribution during cooking. Cooking at 70 °C for 12 min was determined as the best condition for the quality improvement of whole Tartary buckwheat noodles. This is the first study to illustrate the importance of cooking temperatures on the quality of Tartary buckwheat noodles. More consideration must also be given to the optimal cooking conditions for different gluten-free noodles made from minor coarse cereals.

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

The lack of gluten in Tartary buckwheat has always been the main limiting factor of their development. This paper explored how to improve the processing quality of gluten-free Tartary buckwheat noodles (GF-TBNs) by introducing extruded starch into Tartary buckwheat flour (TBF) and the underlying mechanism was also elucidated. Extruded Tartary buckwheat starch (ETBS) was obtained under different extrusion conditions. The thermal properties, molecular weight, and viscosity of ETBS were examined to determine the key parameters closely related to the water distribution and rheological properties of the dough sheet, and tensile properties of GF-TBNs. The results showed that ETBS with a low molecular weight and high viscosity contributed greatly to the GF-TBNs with good tensile properties. It is proposed that ETBS with a low molecular weight and high viscosity might form a gel-entrapped network inside GF-TBNs, which was confirmed by the morphology of GF-TBNs.

Quality Differences between Fresh and Dried Buckwheat Noodles Associated with Water Status and Inner Structure

Buckwheat noodles are mainly sold in the form of fresh and dried noodles in China. Among the noodles with varied proportions of extruded buckwheat flour (20% to 80%), the cooking or textural qualities of fresh and dried buckwheat noodles (FBN and DBN, respectively) were significantly different, and FBN showed a lower cooking loss and breakage ratio and were more elastic than DBN. FBN-20% showed the highest sensory score, followed by DBN-50%. The mechanisms causing the quality differences were investigated using water mobility and the internal structures of the noodles were investigated with low-field nuclear magnetic resonance and scanning electron microscopy, respectively. Compared with FBN, DBN showed a denser internal structure, which explained its higher hardness. The water within FBN and DBN was mainly in the form of softly bound water and tightly bound water, respectively. FBN with highly mobile softly bound water (longer T 22) and a more uniform internal structure had a lower breakage ratio, whereas the trends of water relation with texture properties were different for FBN and DBN. The drying process and added extruded buckwheat flour together contributed to the varied cooking and textural properties.

Effect of extruded starches on the structure, farinograph characteristics and baking behavior of wheat dough

Extruded wheat starch (ES) was obtained by a single-screw extruder to determine its effect on the farinograph, structural properties and baking behaviors of wheat dough. XRD analysis showed that increasing extrusion temperature made the crystalline peaks less pronounced due to the partial gelatinization. In terms of FTIR results, the molecular order of extruded starch was lower than that of native starch. The dough development time was decreased from 3.2 min to 2.7 min while the stability time was increased from 14.4 min to 15.5 min, as 70 ES were added. It was accompanied with increasing levels of α-helix and β-turn transferred from the decreased content of random coil and β -sheet. These effects in bread were to increase loaf volume and reduced loaf hardness. These results indicated that extruded starch had a good potential for producing a high-quality bread.

Effects of Drying Temperature and Relative Humidity on Quality Properties of Chinese Dried Noodles

The influence of the drying conditions on protein structural properties and its impact on Chinese dried noodles (CDN) quality properties is addressed in this study. The CDN were produced under nine different drying conditions utilizing combination of three temperatures (40°C, 60°C, and 80°C) and three relative humidities (65%, 75%, and 85%). The color, texture profile analysis of uncooked and cooked noodles, shrinkage ratio, and cooking quality of CDN were assessed. SEM and FTIR microimaging were investigated to determine the changes in the gluten structural properties. Drying temperature and relative humidity have significant effects on quality characteristics of CDN. However, the influences on different indicators were different. Drying temperature was the main influencing factor of the quality of CDN and protein microstructure. After the drying temperature exceeded 60°C, proteins began to aggregate, and the surface protein distribution became uneven. Compared with cross section, the uniformity of protein distribution on the surface of noodles showed a significant decrease. A high temperature (60°C) could improve the quality of CDN products. The quality of CDN products could be adjusted by the combination of drying temperature and relative humidity.

Impact of aqueous ozone mixing on microbiological, quality and physicochemical characteristics of semi-dried buckwheat noodles

The microbiological, microstructural, and physicochemical impact of aqueous ozone mixing (AOM) on semi-dried buckwheat noodles (SBWN) was elucidated in this study. Microbiological measurements declared that AOM reduced the initial total plate count (TPC) of SBWN significantly (P < 0.05) with a prolonged shelf-life of 2 ~ 5 days. Meanwhile, AOM reduced the cooking loss and water absorption along with the enhancement of hardness and tension force. Scanning electron microscopy (SEM) showed that the protein network of surface and cross section became continuous and compact, and wrapped starch granules more effectively. Moreover, an obvious increase in the intensity of the high molecular protein bands was observed in the sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) patterns. Furthermore, the sodium dodecyl sulfate extractable protein (SDSEP) under non-reducing condition obviously decreased, and then the SDSEP under reducing condition changed insignificantly (P > 0.05). These results indicated that AOM mainly promoted the protein cross-linking of SBWN by disulfide bond (SS) cross-links.

Evaluation of the processing quality of noodle dough containing a high Tartary buckwheat flour content through texture analysis

A texture analysis method for evaluating the processing quality of noodle dough with a high Tartary buckwheat flour (BF) content was established. And then the improvement of wheat flour (WF), wheat gluten (WG), and pre-gelatinized Tartary buckwheat flour (PBF) for the processing quality of buckwheat noodle dough was compared quantitatively, and the mechanism was explored through the observation of gluten network in dough sheets. Texture results showed that the coefficients of variation of tensile strength and adhesiveness of dough sheets among 16 groups were 17.76% and 40.72%, respectively, and the intragroup variation coefficients were only 4.17% and 7.07%, respectively. The tensile strength of dough sheets was significantly positively correlated with gluten index of WF and WG. In addition, with the increase of WG and PBF addition, the tensile strength and adhesiveness of dough sheets showed a linearly increase trend. Furthermore, the gluten network in the dough sheets containing WF or WG with high gluten index distributed more evenly and compactly than that with low gluten index. The dough sheet with 9% PBF showed more uniform gluten network, compared with that without added PBF. Overall, texture analysis of dough sheet can be used to evaluate the processing quality of noodle dough containing 70% BF, and the WF and WG with high gluten index had better improvement than PBF.

Extruded whole buckwheat noodles: effects of processing variables on the degree of starch gelatinization, changes of nutritional components, cooking characteristics and in vitro starch digestibility

The effects of processing variables on the degree of gelatinization (DG), changes of nutritional components, cooking characteristics and in vitro starch digestibility of extruded whole buckwheat noodles were investigated.