Rye grain is a good source of dietary fiber, phenolic compounds, vitamins, and mineral compounds. To prevent the staling process of bread, semi-finished bakery products are subjected to cooling or freezing, and this process is called the postponed baking method. The aim of this study was to examine the influence of rye arabinoxylans differing in molar mass on the properties of rye bread baked using the postponed baking method. The breads were baked from rye flour types 720 and 1150, without and with a 1% share of unmodified or cross-linked rye arabinoxylans (AXs). The molar mass of the unmodified AXs was 432,160 g/mol, while that of the AXs after cross-linking was 1,158,980 g/mol. The results of this study show that the 1% share of AXs significantly increased the water addition to both types of rye flour and dough yield, and this increase was proportional to the molar mass of the AXs used. It is shown that a 1% share of both AX preparations positively increased the volume and crumb moisture of bread baked by the postponed baking method. Cross-linked AXs proved to be particularly effective in increasing the volume and bread crumb moisture. Both AX preparations had a positive effect on reducing the bread crumb hardness of rye breads baked by the postponed baking method.

Amylase activity in rye flour plays a crucial role in the production of rye bread. When preparing a scald in rye bread production, diastatic rye malt is utilized to augment the amylase activity of the rye flour. This study investigated the effects of the diastatic power (DP) and concentration of rye malt on the Falling Number (FN) and the rheological properties of rye flour. Additionally, it examined reducing sugars in the scalding process and fermentation. Mixolab results provided comprehensive data on dough properties at different temperature stages, highlighting significant changes in starch gelatinization and enzyme activity due to varying malt diastatic power and concentrations. The decline in the gelatinization index (C3-C2) indicated faster starch gelatinization with increased diastatic power. Adding rye malt significantly increased maltose content in the saccharified and fermented scald, promoting a favorable environment for lactic acid bacteria and yeasts. FN and Amylograph results showed that less active malt (DP 170, 179 °WK), at a 1.5% concentration, could achieve similar effects as the more active malt (DP 362, 408 °WK) at 0.5%. Adding rye malt to rye flour allows for the regulation of the flour\'s rheological properties and FN, adjustable based on malt DP and concentration.

BACKGROUND: Assessment of IgE-mediated sensitization to flour allergens is widely used to investigate flour-induced occupational asthma. The diagnostic efficiency of detecting specific IgE antibodies (sIgEs) against wheat and rye flour, however, has not been thoroughly compared with other diagnostic procedures.
OBJECTIVE: We sought to evaluate the diagnostic accuracy of sIgE against wheat and rye compared with specific inhalation challenge (SIC) with flour as the reference standard.
METHODS: This retrospective multicenter study included 264 subjects who completed an SIC with flour in eight tertiary centers, of whom 205 subjects showed a positive SIC result.
RESULTS: Compared with SIC, sIgE levels of 0.35 kUA/L or greater against wheat and rye provided similar sensitivities (84% to 85%, respectively), specificities (71% to 78%), positive predictive values (91% to 93%), and negative predictive values (56% to 61%). Increasing the threshold sIgE value to 5.10 kUA/L for wheat and to 6.20 kUA/L for rye provided a specificity of 95% or greater and further enhanced the positive predictive value to 98%. Among subjects with a positive SIC, those who failed to demonstrate sIgE against wheat and rye (n = 26) had significantly lower total serum IgE level and blood and sputum eosinophil counts and a lesser increase in postchallenge FeNO compared with subjects with a detectable sIgE.
CONCLUSIONS: High levels of sIgE against wheat and/or rye flour strongly support a diagnosis of flour-induced occupational asthma without the need to perform an SIC. The absence of detectable sIgE against wheat and rye in subjects with a positive SIC seems to be associated with lower levels of TH2 biomarkers.

The biscuit-making performance of flour depends on both its botanical source and particle size. Several quality parameters of biscuits produced by partial replacement of wheat flour by barley and rye flours at 0, 10, 20, 30 and 40% were measured. Moreover, in order to investigate the effect of particle size, a commercial and two jet milled finer samples of both rye and barley flours were used. For most of the composite flours, the level of substitution was not statistically significant for the weight and the spread ratio of the biscuits. Biscuits with composite flours were softer and darker than the control biscuit (100% wheat flour). In addition, their total phenolics content and antioxidant activity were greater. Among composite flour biscuits, the finer barley flour biscuits were harder than those with the commercial flour. Moreover, as rye flour is darker than wheat and barley flours, rye biscuits were the darker of all. Porosity, bulk and true densities were affected by the particle size of the substitute flours.

Seven types of wheat and rye flours were studied regarding their physical and chemical properties, as well as the presence of mycotoxins and microorganisms. The results revealed that flours presented moisture and ash contents below the recommended maximum limit. They also presented a low lipid content, which helps avoiding changes in the flours\' smell and taste. From the microbiological analysis, comparing the refined rye and wheat flours, the counting in the analysed microorganisms was not significantly different. The whole flours presented high contents in almost all the tested microorganisms, highlighting the molds counting for the whole wheat flour and the aerobic plate counting for the whole rye flour. None of the samples presented Salmonella spp. Aflatoxins and ochratoxin A were not detected in any of the flours. To the best of our knowledge, this is the first characterization of wheat and rye flours for Portuguese consumers.

Wheat (W) and rye flour (R, R1 and R2) films were developed. The rye flours used differed in their particle size. R1 and R2 resulted from jet milling of the R flour at two different feed rates. The mean particle size of W, R, R1 and R2 flours was 173.87, 100.91, 54.59 and 35.66 μm, respectively. Glycerol was used as plasticizer at concentrations of 0.5, 0.7 and 1 g/g of flour. Films made from mixtures of flours (50:50 w/w) were also studied in the presence of 0.7 g glycerol/g of flour. Colour, moisture content, solubility, thickness, viscosity, microstructure and mechanical properties were assessed. In most cases the films were homogeneous. Film moisture content, thickness, opacity and mechanical properties were correlated to glycerol concentration. Particle size was found important for the mechanical properties. Wheat films were lighter ([L*] ≈ 49) and less opaque (135). For both single and composite films, moisture content varied from 24 to 35%, solubility from 43.5-58%, opacity from 135 to 371, thickness from 0.66-0.72 mm and mechanical strength from 0.68-1.7 MPa. All film-forming solutions exhibited shear thinning behaviour. Wheat flour dominated most of the studied properties in composite films. Rye films were more opaque, with relatively high solubility but greater mechanical strength.

Usually the diagnosis of baker\'s asthma is based on specific inhalation challenge with flours. To a certain extent the concentration of specific IgE to flour predicts the outcome of challenge test in bakers. The aim of this study was to evaluate whether the ratio of specific IgE (sIgE) to total IgE (tIgE) improves challenge test prediction in comparison to sIgE alone. Ninety-five bakers with work-related respiratory symptoms were challenged with rye flour. Total IgE, sIgE, and the sIgE/tIgE ratio were determined. Receiver operator characteristic (ROC) plots including the area under the curve (AUC) were calculated using the challenge test as gold-standard. Total IgE and sIgE concentrations, and their ratio were significantly higher in bakers with a positive challenge test than in those with a negative one (p < 0.0001, p < 0.0001, and p = 0.023, respectively). In ROC analysis, AUC was 0.83 for sIgE alone, 0.79 for tIgE, and 0.64 for the ratio. At optimal cut-offs, tIgE, sIgE, and the ratio reached a positive predicted value (PPV) of 95%, 84% and 77%, respectively. In conclusion, calculating the ratio of rye flour-sIgE to tIgE failed to improve the challenge test prediction in our study group.

Finer barley and rye flours were produced by jet milling at two feed rates. The effect of reduced particle size on composition and several physicochemical and mechanical properties of all flours were evaluated. Moisture content decreased as the size of the granules decreased. Differences on ash and protein contents were observed. Jet milling increased the amount of damaged starch in both rye and barley flours. True density increased with decreased particle size whereas porosity and bulk density increased. The solvent retention capacity profile was also affected by jet milling. Barley was richer in phenolics and had greater antioxidant activity than rye. Regarding colour, both rye and barley flours when subjected to jet milling became brighter, whereas their yellowness was not altered significantly. The minimum gelation concentration for all flours was 16%w/v. Barley flour gels were stronger, firmer and more elastic than the rye ones.

BACKGROUND: Sensitization to wheat flour plays an important role in the development and diagnosis of baker\'s asthma.
OBJECTIVE: We evaluated wheat allergen components as sensitizers for bakers with work-related complaints, with consideration of cross-reactivity to grass pollen.
METHODS: Nineteen recombinant wheat flour proteins and 2 cross-reactive carbohydrate determinants were tested by using CAP-FEIA in sera of 101 bakers with wheat flour allergy (40 German, 37 Dutch, and 24 Spanish) and 29 pollen-sensitized control subjects with wheat-specific IgE but without occupational exposure. IgE binding to the single components was inhibited with wheat flour, rye flour, and grass pollen. The diagnostic efficiencies of IgE tests with single allergens and combinations were evaluated by assessing their ability to discriminate between patients with baker\'s allergy and control subjects based on receiver operating characteristic analyses.
RESULTS: Eighty percent of bakers had specific IgE levels of 0.35 kUA/L or greater and 91% had specific IgE levels of 0.1 kUA/L or greater to at least one of the 21 allergens. The highest frequencies of IgE binding were found for thiol reductase (Tri a 27) and the wheat dimeric α-amylase inhibitor 0.19 (Tri a 28). Cross-reactivity to grass pollen was proved for 9 components, and cross-reactivity to rye flour was proved for 18 components. A combination of IgE tests to 5 components, Tri a 27, Tri a 28, tetrameric α-amylase inhibitor CM2 (Tri a 29.02), serine protease inhibitor-like allergen (Tri a 39), and 1-cys-peroxiredoxin (Tri a 32), produced the maximal area under the curve (AUC = 0.84) in receiver operating characteristic analyses, but this was still lower than the AUC for wheat- or rye flour-specific IgE (AUC = 0.89 or 0.88, respectively).
CONCLUSIONS: Component-resolved diagnostics help to distinguish between sensitization caused by occupational flour exposure and wheat seropositivity based on cross-reactivity to grass pollen. For routine diagnosis of baker\'s allergy, however, allergen-specific IgE tests with whole wheat and rye flour extracts remain mandatory because of superior diagnostic sensitivity.

Three years after beginning employment at a bakery, a 32-year-old Japanese man began experiencing acute asthma exacerbations after exposure to rye flour. Antigen-specific serum IgE antibodies were detected to the albumin and globulin, gliadin, prolamin, and glutenin protein fractions of rye flour purified from the crude antigen, but only to the albumin and globulin fraction of wheat flour. The histamine concentration producing one-half maximal effect was lower for all four rye flour fractions than for the wheat flour fractions. After inhalation of the albumin and globulin fraction of rye flour, forced expiratory volume in 1 sec decreased to 77.7% of that pre-provocation. To our knowledge, this is the first report of baker\'s asthma due to rye flour in Japan.