Characterization of wheat gluten subunits by liquid chromatography – Mass spectrometry and their relationship to technological quality of wheat

The quality of common wheat is largely influenced by the composition of its storage proteins. The currently presented research explores factors influencing observed differences in quality and quantity between wheat cultivars, in particular in relation to gluten composition and its relationship to technological characteristics. Eight wheat cultivars (H. Wieser, Seilmeier, W., Belitz, H.D., 1994 Parsi, Sirvan, Sivand, Pishgam, Pishtaz)were selected for evaluation. Analysis results demonstrated that Morvarid and Sirvan cultivars yielded the highest quality of wheat, while the Chamran cultivar was indicated as the most favorable for baking Taftoon bread. Conversely, the Sepahan cultivar was deemed to have the worse quality in both categories. A Q Exactive LC-MS/MS system was employed to evaluate the most effective sub-fractions of gliadin and glutenin on wheat quality. Matching peptides resulting from trypsin digestion on gliadin and glutenin fractions, led to the identification of subunits α/β-gliadin, γ-gliadin, HMW-Dx5, HMW-Bx17, HMW-Dy3, HMW-Dy10, HMW-By15, LMW-m, LMW-s, and LMW-i. The obtained results indicated that the most influential subunits of glutenin on wheat quality were Dy10, Dy3 and Dx5, while the most effective gliadin subfraction was noted to be α/β-gliadin However, the most important subunit influencing the quality of flat breads in particular was identified as the x-HMW-GS, in particular the Bx17 subunit, and LMW-GS.     

Effect of enzymatic and technological treatments on solubilisation of arabinoxylans from brewer's spent grain

Brewer's spent grain (BSG), the most abundant brewing by-product, has hidden and underexploited nutritional potential. In order to valorize BSG, the effects of three commercial xylanases and a peptidase on water unextractable arabinoxylans (WUAX) were studied. Comparing all treatments, higher addition of xylanase resulted in an increase in water extractable arabinoxylans (WEAX). In the most efficient treatment, xylanase alone was able to solubilise 23.7% of WUAX, while the peptidase showed no effect. However, when added together with xylanase, peptidase increased the solubilisation of WUAX up to 1.6 folds. A positive correlation between particle size reduction and solubilisation of WUAX was also proved through milling BSG. These results suggest that access to xylan backbone increases with proteolytic activities, proving a synergistic effect of these specific enzymes. Therefore, if properly treated before being added as ingredient, BSG could add health functionalities to foodstuff while reducing the environmental impact of brewing industries.     

Alpha-amylase treatment increases extractable phenolics and antioxidant capacity of oat (Avena nuda L.) flour

In this work, α-amylase was used to treat oat flour with the intent to release phenolic compounds with known antioxidant properties. After methanol extraction, the amounts of nine beneficial phenolic compounds were measured using HPLC. The antioxidant activities of the extracts were assessed using 2,2′-azinobis (3- ethylbenzothiazoline-6-sulfonic acid) (ABTS)，2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and protein oxidative damage protection assays. Compared with heating-only treated oat flour, that treated with α-amylase showed significant increase of extractable total phenolic content (0.46–1.35 μmol gallic acid equivalents per gram oat), total antioxidant capacity, and an increased ability on the protection of protein from oxidative damage. Heating-only increased caffeic acid and vanillin content by 17 (0.03 vs 0.54 μg/g oat) and 1.8 (0.62 vs 1.11 μg/g oat) folds, but slightly increased the content of other phenols. Excluding heating effect, α-amylase treatment increased gallic acid content by 2.6 folds (0.38 vs 1.38 μg/g oat), caffeic acid content by 2.4 (0.54 vs 1.82 μg/g oat) folds, and other phenols by 1.0–1.8 folds. In conclusion, α-amylase treatment can yield oat products containing more extractable phenolic compounds with increased antioxidant capacity.     

Bioactivity and chemical components of Thai rice in five stages of grain development

Tracking changes in the bioactive compounds of white (ML-W), red (ML-R) and black (RB) rice during the 5 stages of grain development were studied. Total anthocyanin (TAC) was found only in RB (stages 3–5) and proanthocyanidin (TPAC) contents were only found in ML-R (stages 2–5). Considerable amounts of total phenolic contents (TPC) were found in stages 2–4 of ML-R, while total flavonoid contents (TFC) were most detected in stages 4–5 of RB. The DPPH activity of ML-W and ML-R decreased from stages 1–5. The highest FRAP activity was found in ML-R (stages 2–3) indicating that it is highly related to the bioactive compound content. Cyanidin-3-glucoside and peonidin-3-glucoside were found in RB at stages 3–5. The cyanidin of RB in stages 4–5 was related to the amount of TAC. The proanthocyanidin compound catechin was first found and reported in stages 2–3 of ML-R. Principal component analysis indicated that antioxidant activity and the bioactive components were highly related. The data from this study suggests that ML-R at stage 2 and RB at stage 4 are the most suitable stages for harvesting to achieve the highest level of bioactive compounds, which have many health benefits.     

Phenolic Acids,Antioxidant Capacity,and Estimated Glycemic Index of Cookies Added with Brewer’s Spent Grain

Plant Foods for Human Nutrition - Brewers’ spent grain (BSG) is the major by-product of the brewing industry, with great potential as a functional ingredient due to its bioactive compounds....     

Optimization of the ultrasound-assisted extraction of tryptophan and its derivatives from rice (Oryza sativa) grains through a response surface methodology

An analytical ultrasound-assisted extraction (UAE) technique has been optimized and validated for the extraction of tryptophan and its derivatives from rice grains. A Box–Behnken design in conjunction with a response surface methodology based on six factors and three levels was used to evaluate the effects of the studied factors prior to optimizing the UAE conditions. The significant (p < 0.05) response surface models with high coefficients of determination were fitted to the experimental data. The most significant (p < 0.0001) effect is the solvent-to-sample ratio while quadratic effects caused by temperature and solvent-to-sample ratio were of moderate importance (p < 0.05). The optimal UAE conditions were as follows: extraction time of 5 min, ultrasound amplitude of 30%, cycle of 0.7 s⁻¹, extraction temperature of 30 °C, 8% methanol in water as the extraction solvent at pH 3 and a solvent/solid ratio 5:1. The method validation ensured that appropriate values were obtained for the LOD, LOQ, precision and recovery. Furthermore, the method was successfully applied to the analysis of a number of rice samples of different varieties. It was demonstrated that this particular UAE method is an interesting tool for the determination of tryptophan and tryptophan derivatives in rice grain samples.     

Brewers' spent grain: generation,characteristics and potential applications

Brewers' spent grain (BSG) is the major by-product of the brewing industry, representing around 85% of the total by-products generated. BSG is a lignocellulosic material containing about 17% cellulose, 28% non-cellulosic polysaccharides, chiefly arabinoxylans, and 28% lignin. BSG is available in large quantities throughout the year, but its main application has been limited to animal feeding. Nevertheless, due to its high content of protein and fibre (around 20 and 70% dry basis, respectively), it can also serve as an attractive adjunct in human nutrition. Recently, attempts have been made to use BSG in biotechnological processes, such as in cultivation of mushrooms and actinobacteria, as a source of value-added products, such as, ferulic and p-coumaric acids, xylose, arabinose, or as raw material for xylitol and arabitol production. The main characteristics and potential applications of BSG are reviewed focussing on these alternative uses of this agro-industrial by-product as a raw material in foods, in energy production and in biotechnological processes.     

Carotenoid profiling of Hordeum chilense grains: The parental proof for the origin of the high carotenoid content and esterification pattern of tritordeum

The outstanding high carotenoid content of the tritordeum (×Tritordeum Ascherson et Graebner) grains, a promising novel cereal derived from the crossing of durum wheat and the wild barley Hordeum chilense, has previously been assigned as a character derived from the genetic background of its wild parent. The carotenoid profile of H. chilense, especially the lutein esters presented in this study, provide biochemical evidences to confirm this affirmation, being the first time that the individual carotenoid profile of this cereal has been characterized. The total carotenoid content (6.14 ± 0.12 μg/g) and the individual carotenoid composition were very similar to the tritordeum grains, with lutein being the major carotenoid (88%; 5.38 ± 0.11 μg/g) and very low levels of β-carotene. In contrast to tritordeum, H. chilense presented a considerable amount of zeaxanthin (12%; 0.74 ± 0.01 μg/g). Up to 55% of lutein was esterified with palmitic (C16:0) and linoleic (C18:2) acids, presenting a characteristic acylation pattern, in agreement with the tritordeum one, and composed by four monoesters (lutein 3′-O-linoleate, lutein 3-O-linoleate, lutein 3′-O-palmitate and lutein 3-O-palmitate) and four diesters (lutein dilinoleate, lutein 3′-O-linoleate-3-O-palmitate, lutein 3′-O-palmitate-3-O-linoleate, lutein dipalmitate). These data may be useful in the field of carotenoid biofortification of cereals.     

Physicochemical and functional characterization of wheat milling co-products: Fine grinding to achieve high fiber antioxidant-rich fractions

Milling of wheat produces co-products rich in dietary fiber, micronutrients and phytochemicals which can be used to integrate healthy functional foods. In the study different co-products including bran, shorts, and red dog were identified by physicochemical and functional analyses. The results showed that the fat, protein and starch contents decreased in order of red dog > shorts > bran (P < 0.05). The ash, neutral detergent fiber (NDF), acid detergent fiber (ADF), hemicellulose, water and oil holding capacities (WHC, OHC) were in order bran > shorts > red dog, respectively (P < 0.05). Antioxidant capacity was in order red dog > shorts > bran (P < 0.05). The bran was selected as the co-product with the highest fiber that was finely grounded to four different fractions (>355, 250–355, 180–250, <180 μm) and they were characterized more detail. The fat, protein and starch contents decreased with increasing bran particle size (P < 0.05). The ash, crude fiber, NDF, ADF, hemicellulose and WHC and OHC increased with the increasing bran particle size (P < 0.05). DPPH radical scavenging activity increased with increasing particle size (P < 0.05). The bran fractions 250–355 and >355 μm can be used as high fiber ingredients rich in antioxidants to generate functional foods.     

Chemical composition of lipids in brewer's spent grain: A promising source of valuable phytochemicals

Brewer's spent grain (BSG) is an important by-product from the brewing process produced in high amounts worldwide. BSG is rich in carbohydrates, lignin, proteins and lipids. In this work, the chemical composition of the lipids in BSG was studied in detail by gas chromatography and mass spectrometry. The predominant lipids were triglycerides (67% of total extract), followed by a series of free fatty acids (18%). Lower amounts of monoglycerides (1.6%) and diglycerides (7.7%) were also identified among the lipids in BSG, together with minor amounts of other aliphatic series such as n-alkanes and alkylresorcinols. Steroid compounds (steroid hydrocarbons, steroid ketones, free sterols, sterol esters and sterol glycosides) were also found in important amounts in BSG (ca. 5%), with free and conjugated sterols being the most abundant steroids. BSG can thus be regarded as a valuable source of phytochemicals of interest for the pharmaceutical, cosmetic, food or other industries.     

Carotenoid evolution during postharvest storage of durum wheat (Triticum turgidum conv. durum) and tritordeum (×Tritordeum Ascherson et Graebner) grains

The process of in vivo esterification of xanthophylls has proven to be an important part of the post-carotenogenesis metabolism which mediates their accumulation in plants. The biochemical characterization of this process is therefore necessary for obtaining new and improved crop varieties with higher carotenoid contents. This study investigates the impact of postharvest storage conditions on carotenoid composition, with special attention to the esterified pigments (monoesters, diesters and their regioisomers), in durum wheat and tritordeum, a novel cereal with remarkable carotenoid content. For tritordeum grains, the total carotenoid content decreased during the storage period in a clear temperature-dependent manner. On the contrary, carotenoid metabolism in durum wheat was very much dependent on the physiological adaptation of the grains to the imposed conditions. Interestingly, when thermal conditions were more intense (37 °C), a higher carotenoid retention was observed for tritordeum, and was directly related to the de novo esterification of the lutein induced by temperature. The profile of lutein monoester regioisomers was constant during storage, indicating that the regioisomeric selectivity of the XAT enzymes was not altered by temperature. These data can be useful for optimizing the storage conditions of grains favoring a greater contribution of carotenoids from these staple foods.     

The recycling of brewer's processing by-product into ready-to-eat snacks using extrusion technology

Brewer's spent grain (BSG) is the main by-product of the brewing industry. The incorporation of BSG into ready-to-eat expanded products and its effects on the textural and functional properties of extrudates have been studied. Dried and milled BSG at levels of 10–30% was added to the formulation mix made of wheat flour, corn starch and other ingredients. The results obtained from the analysis of the extrudates are discussed in terms of the interaction between the ingredients and effects of processing conditions. The samples were processed in a twin-screw extruder with a combination of parameters including constant feeding rate of 25 kg/h, process temperatures 80–120 °C and screw speeds of 150–350 rpm. Pressure, torque and material temperature during extrusion were recorded. The extrudate properties of nutritional and textural characteristics were measured. Image technique investigations provided useful information on internal structure of the extruded products, total cell area, and their contribution to the appearance and texture. It was found that addition of BSG significantly increased protein content, phytic acid and bulk density, decreased sectional expansion index, individual area and total area of the cells. The higher level of BSG resulted in cells with thicker walls with a rougher surface.     

A systematic micro-dissection of brewers’ spent grain

Brewers’ spent grain (BSG), one of the co-products of the brewing industry, has been mainly used as cattle feed. Spent grain was shown to contain a number of potentially high-value components such as feruloylated arabinoxylan and protein, as confirmed by microscopy and chemical analysis. A significant quantity of starch was also identified, a polysaccharide generally considered to be removed through the malting and mashing steps of brewing. As part of a study to increase the exploitation of spent grain, five separate fractions were prepared through combined milling and vibratory sieving and characterised in terms of chemical composition (polysaccharide composition and linkage; phenolic composition) and by fluorescence microscopy. Material retained on sieve mesh plates of 500, 250 and 150 μm consisted mainly of arabinoxylan-rich palea and lemma, while material passing through 106 and 55 μm sieves was fine, crumb-like material enriched in protein and starch. Lignin was present in all fractions, and originated from the fragmented palea and lemma. The results are discussed in relation to the potential for whole BSG exploitation.     

Sensory properties and aromatic composition of baked snacks containing brewer's spent grain

The incorporation of brewer's spent grain (BSG) into baked snacks (crispy-slices) was investigated in terms of nutritional, sensory and aromatic properties. Wheat flour was replaced with BSG at the levels of 10, 15 and 25%. Snacks containing 10% BSG exhibited high Crispiness index (Ci), low Crispiness work (Wc) and a high number of peaks during texture analysis, indicating that the crispiness of the samples was not negatively affected. However higher levels of BSG affected the texture and the crumb structure of snacks and the results were significantly different to the 100% wheat control. Addition of BSG altered the odour profile of the snacks as shown by the volatile profiles, however sensory results indicated that BSG-containing snacks at a level of 10% were highly acceptable and highlighted the possibility of using BSG as a baking ingredient in the formulation of enhanced fibre baked snacks.     

Phenolic compounds profile in sorghum processed by extrusion cooking and dry heat in a conventional oven

Sorghum (Sorghum bicolor L.) is a gluten-free cereal that has the highest content of phenolic compounds among cereals. It needs to be processed prior to use for human consumption, which may change its antioxidant profile. The knowledge on the effects of extrusion and dry heat in a conventional oven on flavones, flavanones, and proanthocyanidins is limited. Thus, the content and stability to dry heat in a conventional oven (DHCO) and extrusion cooking on phenolic compounds profile in sorghum genotypes were evaluated. Flavanones and flavones decreased after extrusion cooking (100%) and DHCO (31.7–61.6%). The 3-deoxyanthocyanidins were stable in DHCO but were susceptible to extrusion cooking (70.7–93.9%). Proanthocyanidins were identified only in the genotype SC391 and were reduced after both treatments (DHCO: 39.2% and extrusion cooking: 52.1%). Phenols decreased in the genotype SC319 submitted to DHCO (8.3%) and in all extruded genotypes (13.6–14.9%). The DHCO increased the antioxidant capacity in all genotypes, whereas extrusion cooking reduced antioxidant capacity in only two genotypes. In general, differential stability of the major flavonoids in sorghum was observed under DHCO and extrusion cooking, implying that different processing techniques can be selected to minimize losses of bioactive polyphenols in sorghum depending on the flavonoid composition.     

Magnetically modified spent grain for dye removal

Spent grain, the major by-product of the brewing industry, was magnetically modified by contact with water-based magnetic fluid. The prepared material has been used as a new inexpensive magnetic adsorbent for the removal of water-soluble dyes. The dye adsorption could be described both with the Langmuir and Freundlich isotherms. The maximum adsorption capacities reached the value up to 72.4 mg of dye (Bismarck brown Y) per g of dried magnetically modified spent grain.     

Superfine grinding improves functional properties and antioxidant capacities of bran dietary fibre from Qingke (hull-less barley) grown in Qinghai-Tibet Plateau,China

The effect of particle size of hull-less barley (HLB) bran DF on antioxidant and physicochemical properties was investigated. HLB bran and extracted DF was ground by regular and superfine grinding, their particle sizes were determined using laser diffraction method. The results showed that superfine grinding could significantly pulverize DF particles to micro-scale; the particle size distribution was close to a Gaussian distribution. The soluble DF in HLB bran was increased effectively with superfine grinding. Insoluble DF with submicron scale showed increased total phenolic content (TPC), DPPH radical scavenging activity and ferric reducing antioxidant power (FRAP). With particle size reduction, the water retention capacity (WRC), swelling capacity (SC), oil binding capacity (OBC), and nitrite ion absorption capacity (NIAC) were significantly (p < 0.05) increased and the water holding capacity (WHC) had no significant change. A kind of health beneficial DF with higher soluble DF content, WRC, SC, OBC, NIAC and antioxidant activity was obtained using superfine grinding.     

Protease-induced solubilisation of carbohydrates from brewers' spent grain

The impact of microbial proteases on the release of carbohydrates from BSG was studied. The proteases were able to release the non-cellulosic glucose, a portion of feruloylated arabinoxylan and over 50% of the protein from brewers' spent grain (BSG) after 24 h hydrolysis. The non-cellulosic glucose was derived from residual starch-derived products persisting in BSG after mashing. The proteases did not cleave the hydroxycinnamate ester linkages present on the arabinoxylan backbone, and thus do not behave as feruloyl esterases. However, the material solubilised from spent grain by the proteases contained up to 198 μg bound ferulic acid/g extract, which represented 8.6% of the total ferulic acid present in BSG. These results suggest that a portion of water-extractable feruloylated arabinoxylan and starch is trapped within the BSG matrix by a proteinaceous barrier.     

Protease-induced solubilisation of carbohydrates from brewers' spent grain

The impact of microbial proteases on the release of carbohydrates from BSG was studied. The proteases were able to release the non-cellulosic glucose, a portion of feruloylated arabinoxylan and over 50% of the protein from brewers' spent grain (BSG) after 24 h hydrolysis. The non-cellulosic glucose was derived from residual starch-derived products persisting in BSG after mashing. The proteases did not cleave the hydroxycinnamate ester linkages present on the arabinoxylan backbone, and thus do not behave as feruloyl esterases. However, the material solubilised from spent grain by the proteases contained up to 198 μg bound ferulic acid/g extract, which represented 8.6% of the total ferulic acid present in BSG. These results suggest that a portion of water-extractable feruloylated arabinoxylan and starch is trapped within the BSG matrix by a proteinaceous barrier.