Polyphenol Profile and In Vitro Antioxidant and Enzyme Inhibitory Activities of Different Solvent Extracts of Highland Barley Bran.

Five different solvent extracts of highland barley bran were analyzed and compared for their polyphenol profile, antioxidant activity, and α-glucosidase and α-amylase inhibitory activities. The highland barley bran acetone extract had the highest total phenolic content, total flavonoid content, and antioxidant capacity. It was followed by the methanol and ethanol extracts, while n-butanol and ethyl acetate extracts exhibited lower measured values. Diosmetin, luteolin, protocatechuic acid, vanillic acid, ferulic acid, phlorogucinol, diosmin, isoquercitrin, catechin, and isovitexin were among the most abundant phenolic compounds identified in different solvent extracts, and their concentrations varied according to the solvent used. The highest α-glucosidase and α-amylase inhibitory activity were observed in the ethyl acetate extract of highland barley bran, followed by the acetone and methanol extracts. In contrast, n-butanol and ethanol extracts exhibited lower measured values. The different solvent extracts were effective inhibitors for α-glucosidase and α-amylase with activity reaching to 34.45-94.32% and 22.08-35.92% of that of positive control acarbose, respectively. There were obvious correlations between the phenolic content and composition of different solvent extracts and their in vitro antioxidant activity, α-glucosidase inhibition activity and α-amylase inhibition activity. Black barley bran is an excellent natural raw material for developing polyphenol-rich functional foods and shows good antioxidant and hypoglycemic potential to benefit human health.

Effects of high-pressure microfluidization treatment on the structural, physiochemical properties of insoluble dietary fiber in highland barley bran.

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 NO2- 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 NO2- 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.

The structural and functional properties of dietary fibre extracts obtained from highland barley bran through different steam explosion-assisted treatments.

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.

Comparison of distribution and physicochemical properties of ß-glucan extracted from different fractions of highland barley grains.

Highland barley grains were roller-milled to produce five different fractions (B-1, B-2, B-3, B-4, and B-5). The distribution and physicochemical properties of ß-glucans from five roller-milled fractions were investigated. The B-4 fraction contained the highest concentration of ß-glucan (4.40%), and the outermost bran (B-1) had the lowest ß-glucan content (1.01%). Besides, ß-glucans from inner core B-5 (BG-5) had higher Mw (6.482 × 105 g/mol), whereas ß-glucans from outer bran B-1 (BG-1) showed lower Mw (5.859 × 104 g/mol) than those from other fractions. Accordingly, the viscosity of BG-5 was highest (0.038-0.365 Pa·s), and the water solubility index of BG-1 was highest (50.43-90.71%). BG-5 showed stronger foam stability and emulsifying properties but weaker foaming capability, while BG-1 exhibited stronger foaming capability. The foaming capability and emulsifying properties of ß-glucan samples were better under the neutral condition (pH = 7). The foam capabilities of all ß-glucan samples displayed higher values at 65 °C, and emulsifying properties exhibited higher values at 45 °C. This study is expected to promote the application of highland barley ß-glucans in food industry.

Nutritional Component and Chemical Characterization of Chinese Highland Barley Bran Oil.

The nutritional composition and chemical properties of the Chinese highland barley bran oil were characterized in this study. The barley bran oil extracted with solvent possessed relatively high acid value and peroxide value, indicating that the oil should be further refined before using. The fatty acid composition of the oil showed that the content of unsaturated fatty acids was 80.12 g/100 g, in which the content of polyunsaturated fatty acids was as high as 60.41 g/100 g. The overall triacylglycerol profile showed that the oil contained 27 TAGs including 21 regioisomers. Major TAGs included LLL (21.08 g/100 g), PLL (19.27 g/100 g), LLO (12.24 g/100 g), and LLLn (12.17 g/100 g). The total unsaponifiable matter of the oil reached up to 10.74 g/100 g oil. The total phytosterol content reached 7.90 g/100 g oil, in which ß-sitosterol was the most predominant, with the content of 5.69 g/100 g oil. Other important sterols included campesterol (1.32 g/100 g oil), lanosterol (0.70 g/100 g oil) and stigmasterol (0.19 g/100 g oil).

Effects of Highland Barley Bran Extract Rich in Phenolic Acids on the Formation of Nε-Carboxymethyllysine in a Biscuit Model.

Highland barley, a staple food in northwest China, is a well-known source of bioactive phytochemicals, including phenolic compounds. This study evaluated the inhibitory effects of highland barley bran extract (HBBE) on the advanced glycation end product (AGE) levels in a biscuit model, as measured by Nε-carboxymethyllysine (CML) content. CML was detected in all inhibition models using HBBE extracted with different solvents. Under optimal conditions, CML formation in the heated model system composed of glucose/lysine/linoleic acid was effectively inhibited by HBBE. This inhibition effect using extracts from 60% acetone solution was 45.58%. Five major phenolic acids from HBBE (ferulic, syringic, sinapic, p-coumaric, and caffeic acids) were further tested for their trapping and scavenging abilities of glyoxal, a reactive carbonyl species and a key intermediate compound for forming CML. This study has demonstrated that HBBE can potentially control CML formation during food processing, therefore effectively reducing glycation in foods and benefiting those with chronic diseases.