Toward a comprehensive understanding of various milling methods on the physicochemical properties of highland barley flours and eating quality of corresponding sugar-free cookies

Highland barley (HB) was subjected to dry-, semidry-, wet-milling methods and assessed for flour physicochemical properties and eating quality of corresponding sugar-free cookies. Results showed that there were significant differences between different milled flours in damaged starch content, particle size, hydration, pasting properties, and color. High a* values and poor hydration/pasting properties of wet-milled flours were associated with its smallest particle size and lowest content of damaged starch (25.3%), β-glucan (1.87%), and dietary fiber (10.87%), resulting in dark brown color, slightly high spread ratio, low hardness, and fast digestibility of the corresponding cookies. Conversely, the low digestibility of the cookies (predicted glycemic index 58.85) prepared from dry-milled flours was attributed to the higher content of dietary fiber, β-glucan and V-type starch-lipid complex, which would affect enzyme accessibility and may be beneficial for making HB sugar-free cookies. This study is expected to promote the development of HB functional foods.

Extraction and characterization of waxy and normal barley β-glucans and their effects on waxy and normal barley starch pasting and degradation properties and mash filtration rate

Interactions between β-glucan and starch influence the health benefits of barley-based foods and barley brewing performance. Here, we characterized β-glucans from waxy and normal barley varieties and compared the effects of different β-glucans on the pasting and degradation of waxy and normal barley starches as well as the filterability of mashes from unmalted waxy and normal barley. Waxy barley Zangqing18 β-glucan displayed more compact micrographic features, higher molecular weight, larger particle size, higher thermal decomposition temperature and lower rheological viscosity than normal barley Zangqing2000 β-glucan. β-Glucan not only significantly decreased the pasting viscosities of waxy and normal starches but also lowered the pasting temperatures and peak times of normal starch, likely by inhibiting granule swelling and disrupting the integrity of the continuous phase. β-Glucan also decreased in vitro digestion extent of starch and increased the resistant starch. The unmalted waxy barley had a mash filtration rate much faster than normal barley because starch and β-glucan in waxy barley were rapidly and completely digested and formed more open filter passages. The effects of β-glucan on starch properties varied with the types and contents of β-glucans, whilst the types of starches showed more significant effects. CHEMICAL COMPOUNDS STUDIED: β-Glucan (Pubchem CID: 439262); Amylopectin (Pubchem CID: 439207); Starch (Pubchem CID: 156595876).

Highland Barley Starch: Structures, Properties, and Applications

Highland barley (HB) is a nutritious crop with excellent health benefits, and shows promise as an economically important crop with diverse applications. Starch is the main component of HB and has great application potential owing to its unique structural and functional properties. This review details the latest status of research on the isolation, chemical composition, structure, properties, and applications of highland barley starch (HBS). Suggestions regarding how to better comprehend and utilize starches are proposed. The amylopectin content of HBS ranged from 74% to 78%, and can reach 100% in some varieties. Milling and air classification of barley, followed by wet extraction, can yield high-purity HBS. The surface of HBS granules is smooth, and most are oval and disc-shaped. Normal, waxy, and high-amylose HBS have an A-type crystalline. Due to its superb freeze-thaw stability, outstanding stability, and high solubility, HBS is widely used in the food and non-food industries. The digestibility of starch in different HB whole grain products varies widely. Therefore, the suitable HB variety can be selected to achieve the desired glycemic index. Further physicochemical modifications can be applied to expand the variability in starch structures and properties. The findings provide a thorough reference for future research on the utilization of HBS.

Color, Starch Digestibility, and In Vitro Fermentation of Roasted Highland Barley Flour with Different Fractions

Highland barley (HB) is commonly milled into flour for direct consumption or further processed with other food formulations. Nevertheless, the association between milling and HB flour properties remains lacking. This work studied the effect of particle sizes (coarse, 250–500 μm; medium, 150–250 μm; fine, <150 μm) on physicochemical and nutritional properties of raw and sand-roasted HB flour. Gelatinization enthalpy decreased with increasing particle sizes of raw HB flour, while no endothermic transitions were observed in sand-roasted flour. Sand roasting destroyed starch granules and decreased short-range molecular order. Starch digestibility increased while total short-chain fatty acids (SCFAs) production decreased with decreasing particle sizes in all samples. The relative crystallinity of sand-roasted HB flour decreased by 80–88% compared with raw samples. Sand roasting raised in vitro starch digestibility, while total SCFAs during in vitro fecal fermentation decreased. Sand-roasted HB flour with particle sizes <150 μm had the highest starch digestibility (94.0%) but the lowest production of total SCFAs (1.89–2.24 mM). Pearson’s correlation analysis confirmed the relationship between the nutritional qualities of HB flour and milling.

Highland barley starch (Qingke): Structures, properties, modifications, and applications

Highland barley (HB) is mainly composed of starch, which may account for up to 65% of the dry weight to the kernel. HB possesses unique physical and chemical properties and has good industrial application potential. It has also been identified as a minor grain crop with excellent nutritional and health functions. Highland barley starch (HBS) features a number of structural and functional properties that render it a useful material for numerous food and non-food applications. This review summarizes the current status of research on the extraction processes, chemical composition, molecular fine structures, granular morphology, physicochemical properties, digestibility, chemical and physical modifications, and potential uses of HBS. The findings provide a comprehensive reference for further research on HBS and its applications in various food and non-food industries.

Effects of β-glucan and various thermal processing methods on the in vitro digestion of hulless barley starch

This study explored the effects of β-glucan and various processing methods on the digestion of hulless barley starch in vitro. The whole hulless barley showed significantly lower starch digestibility compared to that hydrolyzed by β-glucanase, indicating that β-glucan had inhibitory effects on starch digestion. However, β-glucan slightly accelerated the hydrolysis of extracted starch. Microscope observations of grains and flours revealed that the inhibitory effects of β-glucan benefited from the integral cellular structure of hulless barley. Besides, the hulless barley processed through flaking-roasting and stir-frying exhibited significantly lower starch digestibility (41.5% and 38.9%, respectively) and considerable intact cells and starch granules. The hulless barley processed by steam flash-explosion showed moderate starch digestibility (48.2%), which may be attributed to the encapsulation of starch-protein-β-glucan complexes. This elucidated the possible mechanism of β-glucan limiting the hydrolysis of hulless barley starch and provided useful direction to produce hulless barley products with desirable starch digestibility.

Effects of Two Starch Synthase IIa Isoforms on Grain Components and Other Grain Traits in Barley

Starch biosynthesis in cereal crops is a complex pathway regulated by multiple starch synthetic enzymes. Starch synthase IIa (SSIIa) is well-known to be one of the major starch synthases and is very important in amylopectin biosynthesis. It has significant effects on grain composition and kernel traits. However, there are few reports on the association of natural variation of SSIIa in barley and grain composition and characteristics. In this work, two SSIIa isoforms were first identified as SSIIa^H and SSIIa^L by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis, mass spectrometry, and Western blotting. Sequence analysis of the SSIIa gene demonstrated that a 33 bp insertion coding a peptide of APPSSVVPAKK caused different SSIIa, e.g., SSIIa^H and SSIIa^L. Based on this molecular difference, a polymerase chain reaction marker was developed, which could be used to screen different SSIIa genotypes easily. Kernel hardness of SSIIa^L genotypes was significantly higher than that of SSIIa^H Chinese barley cultivars. The proportion of SSIIa^L genotypes was extremely low in Australian barley cultivars (5/24) and much higher in Tibetan hull-less barley cultivars (46/74), consistent with the end-use requirements of barley grain. This study provided new information in barley endosperm starch synthesis and indicated that it is valuable for choosing the preferred SSIIa genotype according to the end-use requirements.

Nutritional value of barley cereal and better opportunities for its processing as a value-added food: a comprehensive review

Barley is one of the most important cereal crops and arranged globally as fourth after wheat, rice, and corn. It is known for its beneficial effects against degenerative diseases including diabetes, obesity, hypertension, and colon inflammation which are associated with eating habits and improper lifestyles. These effects are mainly attributed to its rich dietary fibers, i.e., β-glucan composition. Moreover, barley considered as a good source of starch, minerals, vitamins, and protein pose it as an ideal food supplement. Nevertheless, about 2% of the barley global production is utilized due to unacceptable organoleptic characters. Therefore, continuous modifications are ongoing either to develop new cultivars for different purposes, or novel processing methods to improve its organoleptic characters. In this review, we provide a comprehensive overview of the macroconstituents and microconstituents of barley, its nutritional value and prebiotic effects. Further, different processing procedures performed to improve its organoleptic characters or to decrease its antinutrient levels are outlined with suggestions for further needed cultivars that could preserve the different benefits of barley and maximize its value as a major cereal crop.

Effects of the addition of waxy and normal hull-less barley flours on the farinograph and pasting properties of composite flours and on the nutritional value, textural qualities, and in vitro digestibility of resultant breads

Hull-less barley (HLB), especially waxy HLB, contains many physiologically active ingredients; however, its poor processing performance and end-product quality are unfavorable. In this study, 80% waxy or normal HLB wholegrain flour (WGF) and 20% wheat flour were used for baking bread. The farinograph and pasting properties of composite powders, and the nutritional value, textural properties, and in vitro hydrolysis of resultant breads were evaluated. The addition of a high proportion of HLB WGFs significantly increased the nutritional value of breads, especially the β-glucan contents of waxy HLB breads. The addition of HLB WGFs and a suitable amount of wheat gluten led to a lower degree of softening of HLB bread flours but improved its farinograph characteristics, such as higher water absorption rate, development time, stability time, and farinograph quality number. Although the sensory profiles of HLB breads were considerably lower than those of wheat bread, they still received a good overall acceptability from a panel of sensory evaluators. HLB breads, particularly the waxy types, exhibited higher hardness, gumminess, chewiness, and lower specific volume, glycemic index and equilibrium concentration in starch hydrolysis. After baking, the starch crystallinity of dough changed from A to V type, and the relative crystallinity decreased. Overall, waxy HLB breads had more nutritional value than normal HLB breads. Higher β-glucan and total dietary fiber content in HLB might have a positive effect on the nutritional value of the resultant breads. However, high β-glucan and total dietary fiber was also accompanied by a negative effect on the sensory quality and processing performance of the end product. PRACTICAL APPLICATION: The composite flour with 80 g hull-less barley wholegrain flour, 20 g wheat flour, and 30 g wheat gluten can be substituted in breadmaking. Compared to wheat bread, hull-less barley bread exhibited different but acceptable sensory properties and had more nutritional value, particularly the waxy one. Therefore, a high proportion of hull-less barley could be recommended for bread production.