Wheat Milling Process Research Articles

Deoxynivalenol in the wheat milling process and wheat-based products and daily intake estimates for the Southern Brazilian population

Fusarium head blight of wheat is caused by the Fusarium species that produces mycotoxins, such as deoxynivalenol (DON). The distribution of DON in wheat products can lead to high economic and health impacts. The objective of this study was to evaluate the natural distribution of DON in the wheat milling process and wheat-based products, as well as the daily intake estimates for the Southern Brazilian population. The fractions of wheat grains (milled wheat, finished flour and bran) were produced in a mill. Additionally, wheat-derived products, such as pasta, bread and crackers were analyzed. The bran fraction had the highest mean concentration of DON (2278 μg kg−1), followed by milled wheat and finished flour (1895 μg kg−1 and 1305 μg kg−1). The distribution factor in the finished flour (69%) fraction demonstrates that DON was reduced when compared to milled wheat, by contrast of bran fraction that presents higher DON levels (120%). A percentage of 35% bran, 35% finished flour and 30% milled wheat samples would not be in compliance with future Brazilian regulations for DON levels. From the wheat-based products analyzed, 17% of whole bread and 10% of salted cracker products were contaminated with DON, with a median of 437 μg kg−1 and 624 μg kg−1, respectively. The finished flour was the fraction that most contributes to the daily intake of DON in Southern Brazil, representing 89.6% of the provisional maximum tolerable daily intake.

Influence of Particle Size of Wheat Powder on Roller Wear Properties

Wheat milling process involves multiple grinding procedures, the wheat powder particles size in different grinding procedure are difference. In order to study the influence of particle size of wheat powder on roller wear performance in different grinding procedure, abrasion experiments were carried out by MLS-225 three-body abrasive wear tester, while different sizes were chosen as abrasive, alloy white iron which frequently used as roller metal materials was chosen as wear sample, wear weight loss and surface microstructure were chosen as the main evaluation indicators. The results showed that the weight loss of samples were showed a linear relationship with wheat the size of wheat powder. The main wear behavior was mainly mechanical polishing while particle sizes was smaller one. For the larger size, wear was made by multiple plastic deformation and low cycle fatigue wear mechanism.

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.

Wheat Mill Stream Properties for Discrete Element Method Modeling

<abstract> <bold><sc>Abstract.</sc></bold> A discrete phase approach based on individual wheat kernel characteristics is needed to overcome the limitations of previous statistical models and accurately predict the milling behavior of wheat. As a first step to develop a discrete element method (DEM) model for the wheat milling process, this study determined the physical and mechanical properties of wheat mill streams (wheat kernels, break stream, and wheat flour) required as input parameters. The parameters measured were particle size and size distribution, bulk density, Young’s modulus, static and rolling coefficients of friction, and coefficient of restitution. The effect of moisture content (12% to 16% wet basis) on these properties was evaluated. The density, Young’s modulus, and coefficient of restitution tended to decrease while the coefficients of friction tended to increase with increasing moisture content of wheat kernels. The effect of moisture content on material properties was significant for break stream, but there was no significant (p > 0.05) material property change with moisture content for flour. It was concluded that moisture content had a greater significant effect on physical properties (bulk, true, and tapped densities and particle size) of the mill streams than it did on the mechanical properties (Young’s modulus, coefficients of static and rolling friction, and coefficient of restitution).

Study of the influence of the milling process on the distribution of deoxynivalenol content from the caryopsis to cooked pasta

The influence of the durum wheat milling process (pre-cleaning, cleaning, hulling, different fineness milling steps) on the deoxynivalenol (DON) content was evaluated, by establishing its contamination distributed in the different products and byproducts (bran, shorts, flour, semolina, and pasta). In order to include also the DON distribution within the pasta manufacturing process, four samples of semolina were worked to obtain four different lots of dried pasta. The results obtained in this study show that, with respect to wheat grain (100%), a reduction of DON contamination of 30%, 66% and 63% in clean wheat, peeled wheat and semolina was observed respectively. On the other hand, an increase of DON contamination was observed in the byproducts, especially in the foliage waste and in the wheat bran fractions, which are intended for feed production. However, at the present time, there is no legal limit set for DON content in feed. As far as the second-stage processing is concerned, with respect to semolina (100%), the observed DON reduction in dry and cooked pasta was estimated 8% and 41% respectively. The overall process, from wheat grain to cooked pasta, leads to a mean DON contamination decrease of 78%. The outputs of this study, confirming the trend of previous works, are of crucial importance in order to early evaluate the safety of the finished products, consistently with their final destination, once the contamination of the raw material is established.

Estimation of Wheat Grain Tissue Cohesion via Laser Induced Breakdown Spectroscopy

During the wheat milling process, the bran fractionation is related to its mechanical properties, which are measured using tensile tests on hand-isolated tissues. However, the dissection of wheat tissues implies a soaking stage in water that can modify tissue properties. New methodologies are required to evaluate wheat tissue properties directly on native grains. The aim of this work was to estimate wheat grain tissue cohesion by the ionization effectiveness via laser-induced breakdown spectroscopy (LIBS) technique. Isolated bran tissues and wheat grains were submitted to LIBS analysis using a pulsed argon fluoride (193 nm, 15 ns, 1 Hz, 2 J cm−2) excimer laser and a compact optic fiber spectrometer (HR2000). The first approach was to correlate the ratios of ionic to atomic emission lines (MgII/MgI and CaII/CaI) of isolated tissues to their mechanical measurements. The energy needed to rupture the tissue was correlated to MgII/MgI (R2 = 0.72). Secondly, native grains were irradiated and chemometrics was applied to discriminate tissue spectra. The aleurone layer isolated after the soaking step presented a higher MgII/MgI than the aleurone layer from native grains, indicating a possible water effect on the tissue cohesion. In conclusion, the LIBS technique may be a potential method for rapid structural analysis of vegetal material allowing wheat population screening of both compositional and mechanical properties.

Physical and Milling Characteristics of Wheat Kernels After Enzyme and Acid Treatments

ABSTRACTThe current wheat milling process separates bran from endosperm by passing tempered wheat kernels through successive break rolls and sifters. Using hydrolytic enzymes during tempering degrades bran and aleurone layers and can improve milling efficiency and yield. This study was conducted to evaluate the effects of chemical and enzymatic treatments of wheat kernels before milling on physical and milling characteristics of the resulting wheat and flour quality. Hard wheat kernels were soaked in dilute acid or water and dried back to original moisture before being tempered with enzymes in water. Kernel physical and milling characteristics (600 g) were evaluated. Dilute acid soaking did not affect the 1,000‐kernel weight and diameter but softened treated kernels. When treated kernels were pearled, bran removal was mostly from ends; and the reducing sugar content in enzyme‐treated bran was significantly higher than the control. Compared with the control, acid‐soaked enzyme‐tempered kernels showed small but significant improvement in straight flour yield, with virtually no difference in protein content, and flour color. Chemical and enzyme treatment resulted in higher ash in flour. These differences were not seen in milling of larger batches (1,500 g) of kernels.