Effect of improved extrusion cooking technology modified buckwheat flour on whole buckwheat dough and noodle quality

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.

Exploring the relationship between starch structure and physicochemical properties: The impact of extrusion on highland barley flour

Highland barley (HB) is an intriguing plateau cereal crop with high nutrition and health benefits. However, abundant dietary fiber and deficient gluten pose challenges to the processing and taste of whole HB products. Extrusion technology has been proved to be effective in overcoming these hurdles, but the association between the structure and physicochemical properties during extrusion remains inadequately unexplored. Therefore, this study aims to comprehensively understand the impact of extrusion conditions on the physicochemical properties of HB flour (HBF) and the multi-scale structure of starch. Results indicated that the nutritional value of HBF were significantly increased (soluble dietary fiber and β-glucan increased by 24.05%, 19.85% respectively) after extrusion. Typical underlying mechanisms based on starch structure were established. High temperature facilitated starch gelatinization, resulting in double helices unwinding, amylose leaching, and starch-lipid complexes forming. These alterations enhanced the water absorption capacity, cold thickening ability, and peak viscosity of HBF. More V-type complexes impeded amylose rearrangement, thus enhancing resistance to retrogradation and thermal stability. Extrusion at high temperature and moisture exhibited similarities to hydrothermal treatment, partly promoting amylose rearrangement and enhancing HBF peak viscosity. Conversely, under low temperature and high moisture, well-swelled starch granules were easily broken into shorter branch-chains by higher shear force, which enhanced the instant solubility and retrogradation resistance of HBF as well as reduced its pasting viscosity and the capacity to form gel networks. Importantly, starch degradation products during this condition were experimentally confirmed from various aspects. This study provided some reference for profiting from extrusion for further development of HB functional food and "clean label" food additives.

Structural modification of starch and protein: From the perspective of gelatinization degree of oat flour

To clarify the relationship between gelatinization degree and structure characteristics, oat kernels were roasted to different gelatinization degree of 15 %-90 % based on tempering water content of 22.5 %-35 %, and the structure characteristics of starch and protein were evaluated. The results showed that the increased gelatinization degree dependent on tempering water content promoted protein aggregation on the surface of starch particles, forming larger aggregates with molecular weight >100 kDa. Oat kernels presented a dense starch gel network structure induced by gelatinized starch. Partial gelatinization of starch led to a decrease in pasting viscosities (setback viscosity, 3.91 Pa·s-1.59 Pa·s) and enthalpy (5.12 J/g-0.11 J/g). With the increase of gelatinization degree, the starch crystal structure conversed from A + V type to V type, accompanied by the formation of starch-lipid complexes and a decrease of relative crystallinity (22.28 %-8.72 %). Moreover, 50 % gelatinized oat flour possessed the highest β-sheet structure (38.04 %), but a decrease in surface hydrophobicity and an increase in endogenous fluorescence intensity were found in oat flour of gelatinization degree >50 %. This study provided a theoretical reference for the application of oat flour with different gelatinization degrees to match suitable products.

Comparative study on nutritional and technological properties of two varieties of black wheat flour and their noodle-making potential

Comparative studies were conducted on physicochemical and technological properties of two black wheat (BW) varieties (cultivated in Shanxi Agricultural University) and their noodle-making potential. Whole-grain BW noodles showed acceptable cooking loss (≤10%) and strong antioxidant capacity. However, their textural quality remains to be enhanced. Regarding refined flour (RF) of the two BW varieties, Yunhei 14207 showed more anthocyanins, brighter color, and greater thermal stability (as reflected by the higher pasting temperature). 16W16 resulted in greater gluten content and better gluten quality of flour and higher dough stability, which contributed to the lower cooking loss and stronger tensile property of noodles. RF noodles of Yunhei 14207 displayed brighter appearance, although they had weaker tensile property. The stronger gluten network in noodles of 16W16 protected phenolics from release and degradation during drying, cooking, and steaming. Despite phenolics loss, RF noodles of Yunhei 14207 showed antioxidant capacity up to 14.97 mg TE/100 g. This research would promote understanding of characteristics of BW varieties. Considering the stronger gluten network of 16W16, its fortification in common wheat noodles at high proportion (>50%) may be promising to develop antioxidant noodles with further improved sensory quality.

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.

Effect of low temperature extrusion-modified potato starch addition on properties of whole wheat dough and texture of whole wheat youtiao

In this study, low temperature extrusion-modified potato starch (MPS) was added to improve properties of whole wheat dough and textural quality of resulted youtiao. Extrusion temperature (60, 90 ℃) and barrel moisture content (30, 42 and 54%) were set as test variables. The results suggested that the low temperature extrusion processing caused moderate gelatinization and improved gel-forming properties of potato starch. MPS addition decreased the setback by up to 46%, and enhanced the viscoelasticity of whole wheat dough significantly. Compared to the whole wheat-based youtiao, the addition of 10% MPS decreased the hardness by up to 72%, and increased the springiness and specific volume by 32% and 22%, respectively. The addition of MPS prepared at lower extrusion temperature (60 ℃) and moderate moisture content (42%) resulted in the optimum textural qualities of whole wheat youtiao. This study will help better understand the role of MPS in whole wheat-based food product.

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.