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This study evaluated the effects of four highland barley proteins (HBPs), namely, albumin, globulin, gliadin and glutenin, on the short-term retrogradation of highland barley starch (HBS). The findings reveal that HBPs could reduce the viscosity, storage modulus and hardness of HBS, with albumin and globulin showing more prominent effects. Furthermore, with the addition of HBPs, the loss tangent (tan δ) of HBS loss increased from 0.07 to 0.10, and the enthalpy of gelatinization decreased from 8.33 to 7.23. The degree of retrogradation (DR%) of HBS was 5.57%, and the DR% decreased by 26.65%, 38.78%, 11.67% and 20.29% with the addition of albumin, globulin, gliadin and glutenin, respectively. Moreover, the relative crystallinity (RC) and the double helix structures were inhibited with the HBPs' incorporation. Meanwhile, the HBPs also could inhibit water migration and improve the structure of HBS gels. In summary, HBPs could inhibit the retrogradation behavior of HBS, which provides new theoretical insights for the production studies of highland barley foods. [ABSTRACT FROM AUTHOR]

BACKGROUND: This study aimed to investigate the effects of semidry milling on the quality attributes of highland barley flour and highland barley bread. Highland barley flours were prepared by dry (DBF), semidry (SBF), and wet (WBF) milling methods. The properties of different highland barley flours were analyzed, and highland barley breads made from different highland barley flours were evaluated. RESULTS: The results showed that WBF had the lowest damaged starch content (15.2 g kg−1), and the contents of damaged starch in SBF‐35 and SBF‐40 (43.5 g kg−1 and 24.1 g kg−1 respectively) were lower than that of DBF (87.6 g kg−1). And SBF‐35 and SBF‐40 with large particles exhibited low hydration performance. In addition, SBF‐35 and SBF‐40 had higher pasting viscosity, pasting temperature, ΔH, and relative crystallinity, consequently resulting in better gel properties than other highland barley flours. These properties could help SBF‐35 and SBF‐40 develop high‐quality bread with large specific volume and superior crumb structure and texture that is similar to the bread with WBF. CONCLUSION: Overall, semidry milling not only could improve the characteristics of HBF, but also avoid high starch damage by dry milling and water wasting by wet milling. What is more, highland barley breads with SBF‐35 and SBF‐40 had preferable appearance and crumb texture. Therefore, semidry milling could be regarded as a feasible way to produce highland barley flour. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Summary: To explore the effects of wet milling method on highland barley flour and highland barley bread, we investigated the characteristics of highland barley flours and the quality of highland barley breads made from whole grain highland barley flour (WGBF), dry‐milled highland barley flour (DBF) and wet‐milled highland barley flour (WBF). Compared to other highland barley flours, WBF had lower damaged starch content (1.37 g/100 g), higher pasting temperature and higher gel strength. In addition, WBF with large particles exhibited low hydration performance. These properties induced a large specific volume (2.62 mL g−1) and good crumb structure of bread with WBF. However, due to the negative effects of damaged starch and insoluble dietary fibre in WGBF and DBF, the specific volumes of bread with WGBF and DBF (1.30 and 1.70 mL g−1) were lower than the bread with WBF. The results showed that WBF with high starch granules integrity could produce preferable highland barley bread. [ABSTRACT FROM AUTHOR]

[Display omitted] • The contribution of fermenting on quality of highland barley vinegar was explored. • 18 volatile compounds were considered as the key volatile compounds. • Isoamyl acetate, acetyl methyl carbinol and ethyl caprylate were aroma biomarkers. • Lactobacillus and Acetobacter were the dominate bacteria during fermentation. • Flavor compounds were correlated to metabolism by dominated microorganisms. Highland barley vinegar, as a solid-state fermentation-type vinegar emerged recently, is well-known in Qinghai-Tibet plateau area of China. This work aimed to explore the main physicochemical factors, key flavor volatile compounds, and dominate microorganisms of highland barley vinegar during fermentation. The results showed that the decrease trend of reducing sugar, pH and the increase trend of amino acid nitrogen were associated with the metabolism of dominate bacteria, especially Lactobacillus and Acetobacter. Totally, 35 volatile compounds mainly including 20 esters, 10 alcohols, 2 aldehydes, 1 ketone and 2 pyrazines and 7 organic acids were identified. Especially, isoamyl acetate, acetyl methyl carbinol, ethyl caprylate, 1,2-propanediol, 3-methyl-1-butanol and ethyl isovalerate with high odor activity values were confirmed as key aroma compounds. Meanwhile, the relative average abundance of bacteria at genus level decreased significantly as fermentation time goes on. Among these microbes, Lactobacillus were the dominate bacteria at alcohol fermentation stage, Lactobacillus and Acetobacter were dominate at acetic acid fermentation stage. Furthermore, the correlations between dominate bacteria and the key volatile compounds were revealed, which highlighted Lactobacillus and Acetobacter were significantly correlated with key volatile compounds (|r| > 0.5, P < 0.01). The fundings of this study provide insights into the flavor and assist to improve the production quality of highland barley vinegar. [ABSTRACT FROM AUTHOR]

The influences of egg white (EW), egg yolk (EY) and whole egg (WE) on the structure of highland barley dough and the quality of highland barley bread were explored. The results showed that egg powder reduced G' and G" of highland barley dough, which led to the softer texture of dough and endowed bread with a larger specific volume. EW increased the percentage of β-sheet of highland barley dough, EY and WE promoted the transformation from random coil to β-sheet and α-helix. Meanwhile, more disulfide bonds were formed from free sulfhydryl groups in the doughs with EY and WE. These properties of highland barley dough could help highland barley bread develop a preferable appearance and textural feature. It is worth noting that highland barley bread containing EY has more flavorful substances and a better crumb structure, which were similar to that of whole wheat bread. The highland barley bread with EY received a high score according to the sensory evaluation in consumer acceptance. [Display omitted] [ABSTRACT FROM AUTHOR]

• Steam explosion pretreatment (SE) increased SDFP yield in highland barley bran. • SE-assisted citric acid or cellulase treatment maintained SDFP thermal stability. • SDFP obtained using SE-assisted ultrasound had the highest water holding capacity. • SDFP obtained using SE-assisted cellulase exhibited the best antioxidant activities. The effects of steam explosion (SE)-assisted ultrasound (SEU), citric acid (SEC), sodium hydroxide (SEA), and cellulase (SEE) treatment on the properties of soluble dietary fibre (SDFP) extracted from highland barley bran were analysed. The results showed that SE pretreatment combined with other methods effectively improves the SDFP yield. The highest yield of SDF (20.01%) was obtained through SEA treatment. SEU-SDFP had a loose and porous structure, whereas the surface of SEC-SDFP and SEA-SDFP presented a complicated and dense texture. Although SE pretreatment reduced the thermal stability of SDFP, SEC and SEE treatment maintained its thermal stability. Furthermore, SEU-SDFP exhibited the highest water and oil holding capacities, and cholesterol and nitrite ion adsorption capacities. SEE-SDFP exhibited the best DPPH and ABTS radical scavenging abilities. In summary, four SE-assisted extraction methods had different advantages, and highland barley bran SDF can be considered as a potential functional additive in the food industry. [ABSTRACT FROM AUTHOR]

High-pressure microfluidization treatment (HPMT) was performed on the insoluble dietary fiber (IDF) of highland barley bran (HBB), with conditions set at 60 MPa (IDF-60), 120 MPa (IDF-120), and two consecutive high-pressure treatments at 120 MPa (IDF-120-2), respectively. Then the particle size, structural, physicochemical and adsorption properties of different IDF samples were analyzed. After HPMT, the particle size of IDF samples gradiently decreased (p < 0.05), and part of IDF was transferred into soluble dietary fiber (SDF), accompanied by the decrease of hemicellulose and lignin content. In addition, the morphology of the IDF samples became more fragmented and wrinkled, and the two consecutive treatments at 120 MPa significantly damaged the crystalline structure of the IDF. Moreover, the adsorption capacities to water, oil, cholesterol, and NO 2 − were basically enhanced with the increase of treatment pressure and treatment number. The IDF-120-2 sample had the strongest water/oil-holding, swelling, and cholesterol trapping capacities, and the IDF-120 showed strongest NO 2 − trapping capacity (pH = 2). Through the correlation analysis, the adsorption capacities were positively to the particle size and SDF content, and negatively correlated with the specific surface area (SSA) and IDF content. The adsorption capacities of IDF for the four substances were positively correlated with each other. [Display omitted] • Particle size (PS) of insoluble dietary fiber (IDF) decreased after high-pressure microfluidization treatment (HPMT). • HPMT increased the specific surface area (SSA) of the IDF and partially destroyed the crystalline structure of the IDF. • Water/oil holding capacity of modified IDF increased by 46.71% and 54.4%. • Adsorption capacity (AC) of modified IDF for cholesterol and NO 2 - increased by 68.03% and 19.63%. • AC of modified IDF was positively to the PS, SDF content, and negatively to the SSA and IDF content. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare the structural, thermal, rheological and digestive properties of highland barley starch (HBS) by different extraction methods. Five techniques were used to extract HBS: Alkali extraction, Ultrasound extraction, double enzyme extraction (DE), three enzyme extraction (TE) and ultrasonic assisted TE (U-TE). The results indicated that the Ultrasound extracted HBS had fewer Maltese crosses, lower molecular weight (Mw), and higher content of damaged starch (P < 0.05). Meanwhile, DE extracted HBS had higher Mw, and the content of short amylopectin than that of Alkali extracted HBS (P < 0.05). Additionally, the DE extracted HBS showed the highest relative crystallinity and good short-range ordered structure, which led to the outcome of stronger thermal stability and higher values of G′ and G′′ (P < 0.05). These results indicated that enzymatic extraction could better protect the resistance of HBS by protecting its physicochemical properties. [Display omitted] • Double enzyme extraction (DE) had advantages in retaining the antidigestibility of HBS. • DE had the highest relative crystallinity (26.05%) and the content of RS (14.23%). • Alkali had lowest thermal stability and rheological properties. • The digestibility of DE (86.65%) was significantly lower than Alkali (93.18%). [ABSTRACT FROM AUTHOR]

[Display omitted] • Continuous instant pressure drop (CIPD) affected thermal and pasting properties. • CIPD enhanced gelatinization stability of whole highland barley flour (WHBF). • A total of 68 volatile compounds were identified in raw WHBF. • CIPD preserved the original flavor of WHBF better than traditional hot air treatment. Continuous instant pressure drop (CIPD) treatment effectively reduces microbial contamination in whole highland barley flour (WHBF). Base on it, this study further investigated its effects on flour properties (especially rheological properties) and volatile compounds (VOCs) profile of WHBF, and compared it with that of ultraviolet-C (UV-C), ozone and hot air (HA) treatments. The results showed that the damaged starch content (6.0%) of CIPD-treated WHBF was increased, leading to a rough surface and partial aggregation of starch particle, thereby increasing the particle size (18.06 μm of D10, 261.46 μm of D50 and 534.44 μm of D90). Besides, CIPD treatment exerted a positive influence on the structure and rheological properties of WHBF, including an elevation in pasting temperature and viscosity. Notably, CIPD-treated WHBF exhibited higher storage modulus and loss modulus compared to the other three groups of sterilization treatments, contributing to the formulation of a better-defined and stable gel strength (tan δ = 0.38). UV-C and ozone, as cold sterilization techniques, also induced alterations in specific characteristics of WHBF. UV-C treatment led to changes in WHBF's crystallinity, while ozone treatment caused modifications in the secondary protein structure of WHBF. A total of 68 VOCs were identified in raw WHBF (including 3 acids, 19 alcohols, 25 aldehydes, 1 alkene, 8 esters, 2 ethers, 3 furans, and 7 ketones). The maximum flavor-contributing VOC in CIPD-treated WHBF remained dimethyl sulfide monomer (cabbage aroma), consistent with the raw WHBF. Conversely, in HA-treated WHBF, the maximum flavor-contributing VOC shifted to 2-furanmethanethiol monomer (roasted coffee aroma), altering the initial flavor presentation. These findings will provide strong support for the application of CIPD technology in the powdery foods industry. [ABSTRACT FROM AUTHOR]