Wheat Milling Fractions Research Articles

Analysis of mixed linkage β-glucan content and structure in different wheat flour milling fractions

β-glucan is a dietary fibre component with health benefits that relate to its structure and solubility. The polysaccharide structure consists predominantly of β-(1–4) linked cellotriosyl (G3) and cellotetraosyl (G4) units joined together with β-(1,3) linkages. The ratio of G3:G4 blocks affects the solubility with very high or very low ratios causing lower solubility. Wheat, a major staple crop, is a source of β-glucan in the human diet; however, there is a lack of research on β-glucan in wheat, especially white flour which is used in many food products. Here we quantified β-glucan in different wheat milling fractions, showing a low content in the first and second break (white) flour fractions (0.2%) with increasing amounts in bran flour (0.5%), wholemeal (0.8%) and bran (2.8%). A high proportion (30%) of β-glucan in the white flour fractions was soluble, while in bran a far smaller proportion (10%) was soluble. In agreement with differences in solubility, the G3:G4 ratio also differed, with the white flour fractions having lower ratios (∼2.5) and bran-containing fractions having higher ratios (∼3.8). We conclude that while total β-glucan in white flour is low, it is substantially soluble, and that high extraction and wholemeal flours have the potential to be a significant source of β-glucan.

Bran-Enriched Milled Durum Wheat Fractions Obtained Using Innovative Micronization and Air-Classification Pilot Plants

Dietary guidelines recommend the consumption of unprocessed, or minimally processed, wheat foods because they are richer in health-promoting components (i.e., minerals, vitamins, lignans, phytoestrogens, and phenolic compounds) compared to traditionally refined products. The design and implementation of technological solutions applied to the milling process are becoming a key requirement to obtain less refined mill products characterized by healthier nutritional profiles. This study presents the development of an upgraded micronization plant and of a modified air-classification plant to produce several novel types of durum wheat milling fractions, each enriched in bran particles of different sizes (from 425 µm > Ø to Ø < 180 µm) and percentage ratios. A preliminary quality assessment of the milling fractions was carried out by measuring yield percentages and ash content, the latter being related to detect the presence of bran particles. A wide array of milling fractions with different original particle size compositions was provided through the study of the process. Results indicate the ability of the novel pilot plants to produce several types of less refined milling fractions of potential interest for manufacturing durum wheat end-products beneficial for human health.

Development of functional foods using psyllium husk and wheat bran fractions: Phytic acid contents.

Wheat grain is a rich source of phosphorus which is present mostly as phytic acid and is distributed mainly in the bran and germ fractions. Phytic acid has now been recognized as an important phytochemical having antioxidant properties. This study deals with the determination of total as well as phytic phosphorus contents of psyllium (PS), course (CB) and fine wheat bran (FB) enriched pan bread and Arabic flat bread. The concentration of phytic acid in CB, FB, wheat germ, wholegrain wheat flour (WGF), white wheat flour (WWF), and psyllium were found to be 8.86 mg/g, 8.52 mg/g, 6.05 mg/g, 1.74 mg/g, 0.46 mg/g and 0.02 mg/g, respectively. Most of the phosphorus existed as phytic phosphorus (74.7–90.8%) in FB, CB, germ, and WGF as compared to only 42.6% in WWF. The level of phytic phosphorus in pan bread containing 10% CB, 20% FB (both containing with 5% PS) was found to be 0.63 mg/g and 1.53 mg/g respectively, as compared to only 0.34 mg/g in WWF pan bread, and 0.90 mg/g in WGF pan bread. The phytic phosphorus content in Arabic bread made with WGF and 3% psyllium was 1.32 mg/g as compared to only 0.48 mg/g in WWF Arabic flat bread. The results obtained indicate that the level of phytic phosphorus significantly increased in bread formulations containing CB, FB, and WGF, but no change with psyllium addition was observed. Adding these wheat mill fractions, and psyllium will enable bakeries not only to produce fiber-enriched pan bread and Arabic bread but would also benefit consumers to increase their dietary fiber intakes, and health-promoting phytochemicals coming from wheat bran and germ fractions.

Influence of heat treatment for some wheat milling fractions on fino bread quality.

The influence of incorporating dry-heated wheat bran, at 5, 10, 15, and 20g/100g levels with dry-heated wheat germ at 3g/100g level, on fino dough rheology and bread quality was studied in comparison with fino bread containing unheated fractions, and white wheat bread. Dry heat treatment showed insignificant effects on the chemical composition and the dietary fibers of wheat bran and wheat germ, but was effective in reducing lipase activity by half in wheat bran, and by 100% in wheat germ. Dough containing dry heated fractions lowered the water absorption, extended the development time, strengthened the protein network, and increased the stability time, starch gelatinization, hot-gel stability, and starch retrogradation. Fino bread had larger loaf volume, darker crumb color, and lesser firm, gummy, and chewy texture. Sensory acceptability of fino bread loaves containing heated fractions indicated significant (P ≤ 0.05) improvement in taste, flavor and overall acceptability scores. Fino bread provided 9.0 to 21.5% of the dietary fiber intake (DFI) for the adults, showed significant loss of phytic acid (30-34%), had higher significant total phenolic contents (109.2-198.2mg GAE/100g), and antioxidant activity (40.17-47.46%). Levels of 10 and 15g heated bran with 3g heated germ/100g showed acceptable results among all studied characteristics. Dry heat treatment could be applied on wheat bran and wheat germ to mitigate their negative influences on dough rheological behavior, and to deliver functional fino bread to consumers, with more dietary fiber, high-quality nutrients and antioxidant activity.

Phenolic acid contents and antioxidant activities of wheat milling fractions and the effect of flour extraction rate on antioxidant activity of bread

Phenolic acid contents and antioxidant activities of wheat milling fractions and the effect of flour extraction rate on antioxidant activity of bread

Study on the variation of stable isotopic fingerprints of wheat kernel along with milling processing

In the present study, the variation of stable isotopic ratio of carbon and nitrogen in wheat kernel along with milling fractions (bran, germ, break flour, reduction flour) in three genotypes from three different locations in five years (2012–2016) was investigated. Isotope ratio mass spectrometry (IRMS) was used to analyze the samples. Analysis of variance revealed significant differences among regions, genotypes, years, and their interactions for all wheat fractions. Region showed the largest variability in the δ13C and δ15N values of wholemeal and different fractions. A Significant positive correlation was found between whole kernel and different milling fractions for both carbon and nitrogen isotopes suggesting reliability of fractions fingerprints for geographical traceability of wheat. Moreover, a classification model based on the canonical discriminant analysis (CDA) was built which correctly classify 93.8% samples in all regions using light stable carbon and nitrogen isotope of whole wheat and milling fractions. Present findings significantly contribute to understand the variations of isotopic composition in different wheat milling fractions depending on geographical origins and offer valuable insight into the control of mislabeling regarding geographical origin.

Impact of pre-harvest rainfall on the distribution of fusarium mycotoxins in wheat mill fractions

Legislative limits for Fusarium mycotoxins decrease from unprocessed wheat to processed products. A previous observational study identified a seasonal difference in the distribution of deoxynivalenol (DON) but not zearalenone (ZON) within mill fractions. Rainfall is known to influence the production of these mycotoxins in wheat, but the effects of rainfall on their distribution within mill fractions is not known. Laboratory and field experiments were conducted to determine the impact of different watering regimes on the distribution of DON and ZON in wheat mill fractions. Results indicated that repeated wetting and drying could cause movement of DON towards equilibrium across the mill fractions. Whereas, high levels of rainfall could cause a large reduction of DON in the grain, predominantly from the bran fraction, resulting in a proportional increase within white flour. ZON was detectable in fewer samples but results indicated it is less mobile within the grain. It is important for processors to be aware of the variation of mycotoxin distribution within mill fractions and the drivers of this variation to ensure limits set for grain intake result in mill products within mycotoxin legislative limits.

Monitoring of heat-treated wheat milling fractions by near infrared spectroscopic method

Near infrared (NIR) technology is used effectively in the quality control field of cereal science and technology. The aim of this study is to elaborate on the usage of the near-infrared method for testing purposes, as well as on the recognition of the heat-treatment effects in the case of wheat milling fractions and changes in quality in these fractions. The heat treatment processes are being applied to increase the shelf life properties of products or to change the physical/rheological properties of goods. The wheat products and fractions examined in this study had been produced under industrial conditions The following products have been analysed: Hungarian wheat fraction (WF), Hungarian cake flour (CF) and aleurone-rich wheat flour (ARF). These basic flours were originated and produced by Gyermelyi Corp. flour mill. After that, the entire heat treatment process of WF, CF, ARF flour fractions were achieved and completed in cooperation of Buhler AG and Budapest University of Technology and Economics. The samples were collected based on the heat treatments, and involved hydrothermal and dry-thermal treated samples as well as untreated samples. The changes in the main chemical components (such as starch and protein) were analysed with dispersive spectrophotometers, using visible and NIR regions of the electromagnetic radiation with regards to the heat treatments. Close correlation has been established between the data of spectroscopic measurement techniques processed by various chemometric methods (e.g. principal component analysis, cluster analysis) and the types of treatments that were used. Not only differences caused by the milling technology and the heat treatment settings have been clearly observed, but also differences between the dry-thermal and the hydrothermal treatment. During this task, it became obvious that the NIR methods can detect the deviation in parameters of the heat treatments.

Characterizations of stable carbon and nitrogen isotopic ratios in wheat fractions and their feasibility for geographical traceability: A preliminary study

The study aims to investigate the characterization of stable isotopic ratios in wheat milling fractions (bran, wheat shorts, and flour) and extracts (defatted flour, gluten, lipid, starch, and crude fiber) and correlations among different matrices for each isotope, which could provide some references for the development and application of stable isotopes for geographical traceability of wheat and its milling products. Wheat samples with three genotypes were collected from three regions in China. δ13C and δ15N values in wholemeal, milling fractions and extracts were determined. Results showed that δ13C varied significantly among milling fractions and extracts, while no significant difference was found among δ15N values of different milling fractions or extracts. Each isotope shows significantly positive correlations among wheat fractions (p < 0.01). The variations of δ13C and δ15N were most contributed by fraction and region, respectively. Therefore, δ15N is suitable for geographical traceability of wheat and its milling products.

Total Phenolic and Yellow Pigment Contents and Antioxidant Activities of Durum Wheat Milling Fractions.

The aim of this study was to investigate the distribution of total yellow pigments, total phenolic compounds, and their antioxidant activities in various durum wheat milling fractions. Carotenoid composition of yellow pigment extract was also examined using UPLC. The ABTS radical scavenging activity of the milling fractions decreased in the order of short bran/bran > feed flour > flour/semolina in both total phenolic and total yellow pigment extracts. Yellow pigments extracts from bran, short bran, and feed flour exhibited 5.6–15.4% higher antioxidant activity than those of total phenolic extracts from the corresponding milling fractions. The UPLC results showed a non-carotenoid peak at Rt 0.47 min which was present in fractions of the grain outer layers but absent in semolina and flour. This peak absorbed in the UV range of 271 to 327 nm. These observations suggest that the unknown peak could be composed of phenolic compounds co-extracted in their free form with carotenoids in the polar water-saturated butanol solvent. The compounds in this peak could result in overestimation of carotenoid content and antioxidant activity in bran, short bran and feed flour as the peak contributed to 18.3–26.0% of total carotenoids if it was taken into account.

Deoxynivalenol in wheat milling fractions: A critical evaluation regarding ongoing and new legislation limits

New maximum limits (ML) for deoxynivalenol (DON) in wheat and its products were set in Brazil in 2017, and new changes are scheduled for 2019. The concentration of DON in wheat and milling fractions (bran, shorts, break flour, reduction flour) was evaluated in samples from commercial fields to discuss the effects of the new legislation. Cleaned wheat samples contaminated with DON had concentrations ranging from 308 to 2373 ng g−1 (n = 29), and one sample had a concentration of 3426 ng g−1. DON concentration obtained in bran and shorts were significantly higher than that of the flours. Compared to the initial concentration in cleaned wheat, DON relative concentrations were 73 and 35% higher in bran and shorts, respectively, and 67% lower in the straight run flour (break plus reduction flour). The bran and straight run flour contained DON concentrations that were 62.1 and 17.2% respectively higher than that of the ML set in Brazil in 2017; additionally, these values would reach 65.5 and 34.5%, respectively, according to the changes to be in effect in 2019. The present study demonstrates DON distribution in wheat milling fractions, thus, providing updated information for the management of DON contamination for the industry and policymakers.

O–H–C stable isotopes as discriminant markers for fruits botanical origin

In the present study, the variation of stable isotopic ratio of carbon and nitrogen in wheat kernel along with milling fractions (bran, germ, break flour, reduction flour) in three genotypes from three different locations in five years (2012–2016) was investigated. Isotope ratio mass spectrometry (IRMS) was used to analyze the samples. Analysis of variance revealed significant differences among regions, genotypes, years, and their interactions for all wheat fractions. Region showed the largest variability in the δ13C and δ15N values of wholemeal and different fractions. A Significant positive correlation was found between whole kernel and different milling fractions for both carbon and nitrogen isotopes suggesting reliability of fractions fingerprints for geographical traceability of wheat. Moreover, a classification model based on the canonical discriminant analysis (CDA) was built which correctly classify 93.8% samples in all regions using light stable carbon and nitrogen isotope of whole wheat and milling fractions. Present findings significantly contribute to understand the variations of isotopic composition in different wheat milling fractions depending on geographical origins and offer valuable insight into the control of mislabeling regarding geographical origin.

A novel method for ash analysis in wheat milling fractions by using laser-induced breakdown spectroscopy

Ash content is an important quality control parameter in milling industry. Measurement of ash content is routinely performed using standard ash analysis method in which the sample is burned at 500–600 °C for 5–6 h. However, this method is not convenient for industrial applications, and thus, rapid and reliable methods are needed to be developed. The aim of this study was to develop a new method for ash analysis to be used in wheat milling fractions by using laser induced breakdown spectroscopy (LIBS). LIBS is an optic based multi-elemental, spectroscopic method which can analyze high number of samples in a considerably short time. In the study, wheat flour, whole wheat meal and semolina samples with different ash contents were analyzed using LIBS, and the spectra were evaluated with partial least squares (PLS) method. The results were correlated with the ones taken from standard ash analysis method. Calibration graph showed good linearity with the ash content between 0.48 and 2.44%, and 0.997 coefficient of determination (R2). Limit of detection for ash analysis was calculated as 0.11%. The results indicated that LIBS is a promising and reliable method with high sensitivity for routine ash analysis in milling industry.

Change in B and E vitamin and lutein, β-sitosterol contents in industrial milling fractions and during toasted bread production

Wheat constitutes a major part of the daily diet in Europe and represents an important source of vitamins. Thus, it is important to monitor the levels of vitamins upon the wheat-based foods processing operations, such as production of new wheat milling fractions, bread and breadmaking toasted bread. The variability in B and E vitamin, and Lutein, β-sitosterol contents were measured in semi-coarse wheat flours and milled fractions obtained from industrial milling company, as well as in the toasted breads made from them by means of LC-MS/MS and stable isotope dilution assay. The concentration of nicotinic acid, pyridoxal, pyridoxine, pantothenic acid, β-γ-tocopherol were significantly higher in the coarse bran, while an important amount of lipid-soluble bioactive compounds was recovered in the discard sifting. The toasting step induced a significant increase of α-tocopherol (+216%), β-γ-tocopherol (+52%), α-tocotrienol (+83%), β-γ-tocotrienol (+32%), nicotinic acid (+55%), nicotinamide (+97%) and of pyridoxine (+77%). Our finding emphasized the need to determine for each bioactive compounds the part which is bioavailable in the interesting part of the bran. In addition, we demonstrated that the toasting process can release bound bioactive compounds and led to enhance the nutritional quality of toasting bread.

Effect of cleaning, sorting and milling processes in wheat mycotoxin content

Mycotoxins are a ubiquitous contaminant and are difficult to prevent or to diminish; it is, therefore, important to establish the contributions of processing steps to eliminating mycotoxins in the production of safer foods. The objective of this study was to investigate the effects of wheat cleaning, sorting, and milling processes on Fusarium mycotoxin distribution in two naturally contaminated wheat cultivars. The study focused on evaluating the effects of first-stage processing methods, cleaning, and gravity separator, on wheat mycotoxin content. The distribution of Fusarium mycotoxins was analyzed after two milling processes. Firstly, a Laboratory Mill 3100 was used to obtain the whole milled wheat. Secondly, a pilot-scale mill Quadrumat Senior was used to get wheat milled fractions (finished flour and bran). Wheat samples (BRS Parrudo and BRS 374) were collected during the 2014 season that were highly vulnerable to Fusarium outbreaks in Southern Brazil. Fusarium toxin (DON, 3-ADON, 15-ADON, NIV, and ZON) levels were determined for all milled fractions via chromatography (UHPLC-MS/MS). The cleaning and sorting methods employed post-harvest significantly reduced the mycotoxin content in wheat. The reduction of mycotoxin was progressive through each processing method, and the gravity separator equipment resulted in the lowest contamination levels in products intended for human consumption for both cultivars. Through the milling process, the DON contamination in finished flour was significantly lower than in milled wheat; however, there were no significant differences in contamination between the milled wheat and bran. The cleaning and sorting methods for both wheat cultivars generated safer foods when compared with unsorted wheat samples (BRS Parrudo and BRS 374).

Distribution of Fusarium mycotoxins in wheat milling process

Fusarium head blight (FHB) is a fungal disease that affects cereals and is capable of producing mycotoxins, creating health concerns. In southern Brazil, FHB of wheat is caused by the Fusarium graminearum species complex that produces mainly deoxynivalenol (DON) and zearalenone (ZON) mycotoxins. There is a need for research-based information on how different contamination levels affect these mycotoxins' distribution in the milling process. The objective of this study was to analyze the Fusarium mycotoxin distribution within each milled fraction, extracted from wheat lots artificially contaminated with a crescent gradient of mycotoxins. Wheat samples produced in 2013 season in Southern Brazil region were obtained from plots of breeding program. The wheat samples were artificially contaminated with residues of cleaning and pre-cleaning process, including light and shriveled grains, obtained from a Fusarium nursery screening plot. Pilot-scale milled wheat fractions were collected, comprising finished flour and bran. The Fusarium mycotoxin content was determined by chromatography (UHPLC-MS/MS). The results obtained show that DON presented exponential growth relative to the initial levels of mycotoxin in wheat milled fractions (finished flour and bran). The DON concentration was significativelly higher in bran, when compared with milled wheat and finished flour, in the DON levels lower than 1000 μg kg−1. The finished flour presented lower DON levels when compared with milled wheat, but this reduction was inadequate, to meet the current regulation limits for food.

From wheat to sourdough bread: a laboratory scale study on the fate of deoxynivalenol content

The effect of wheat processing by scouring, milling and sourdough bread making on the fate of deoxynivalenol was studied using wheat samples artificially contaminated with Fusarium graminearum. The scourer assures an intensive treatment of grain surface, allowing the reduction of deoxynivalenol content by 34.6-46.2%. After milling, the deoxynivalenol was found in all wheat mill fractions. The highest deoxynivalenol contents were found in bran fractions (bran and shorts). Concerning the flour fractions, those with low ash content, resulting from the first break and first reduction flours, were found to have higher deoxynivalenol concentrations than other flour fractions. The sourdough fermentation with selected lactic acid bacteria allowed the significant decrease (58.6-66.5%) of deoxynivalenol content of flour, while the spontaneous fermentation induced a much lower decrease (26.2-29.1%). The baking process caused the reduction of deoxynivalenol content by 11.4-15.5% compared to fermented dough.

Baking properties and biochemical composition of wheat flour with bran and shorts

Bran, being a by-product of grain grinding, is characterised by a high biological value and is thus widely used in food production. In this study, different streams of bran and shorts from the wheat graded milling process were incorporated into wheat flour at levels of 5, 11, 17 and 23% (w/w) to investigate their influence on the nutritional and baking properties of flour. Bran and shorts streams improved the baking properties of flour blends. The best result in the case of graded flour blends with different bran products was obtained at the 95:5 ratio. The products containing peripheral parts of grain had higher proteolytic enzyme and superoxide dismutase activities and lower trypsin inhibitor content and β-amylase activity compared with graded flour. Streams of wheat milled fractions including peripheral parts of grain increase the content of bioactive substances and dietary fibre in blends with wheat graded flour.

Properties of Arabinoxylans from Wheat Bran, Shorts and Flour

Arabinoxylans were prepared from bran, shorts and flour, three wheat milling fractions. The yields of bran arabinoxylan (WBAX), shorts arabinoxylan ( WSAX) and flour arabinoxylan ( WFAX) were 8.99%, 7.28% and 1.12% respectively. Sugar composition analysis showed that WFAX contained less non-cellulosic sugars ( 75.56%) compared with WFAX and WSAX. WBAX had the lowest Ara/Xyl ratio compared with WSAX and WFAX. HPSEC analysis showed that WFAX had higher molecular weight compared with WBAX and WSAX, and WBAX had the lowest molecular weight. WBAX, WSAX and WFAX in water solution had higher molecular weight than in 0.5mol/L NaOH and 1.0mol/L NaOH. In 1.0 mol/L NaOH solution, arabinoxylans had the lowest molecular weight compared that in 0.5 mol/L NaOH and distilled water. From the recovery of WBAX, WSAX and WFAX in different solvents, it showed that 1.0N NaOH had good dissolved effect for arabinoxylans, and water heating treatment ( 80°C 2hr, then stirring overnight at room temperature) had poor dissolved properties compared with 0.5 mol/L NaOH and 1.0 mol/L NaOH ( 25°C,2hr)

Assessment of antioxidant activity and rheological properties of wheat and buckwheat milling fractions

This study examined the antioxidant properties of the ethanolic extracts of wheat milling fractions (wheat flour type 500 and type 850, and bran) and their polyphenol and tocopherol content, and rheological characteristics of wheat dough supplemented with buckwheat flours (light and wholegrain). The results obtained in this study were correlated with our previously published data on wheat flour type 400, wholegrain wheat flour and buckwheat flours. Buckwheat flours exhibited significantly higher ( P < 0.05) antiradical activity on hydroxyl ( OH), superoxide anion (O 2 −) and (1,1-diphenyl-2-picrylhydrazyl) DPPH radicals, antioxidant activity and reducing power than all investigated wheat milling fractions when their corresponding IC 50 values were compared. The rheological parameters of wheat dough supplemented with light and wholegrain buckwheat flour (0–50%) were obtained by using Mixolab. Results indicated changes in protein and starch properties of dough. The obtained results indicate the benefit of using buckwheat flours in wheat-based food products, i.e. their contribution in functional and tailor-made-food production.