Effects of tempering with steam on the water distribution of wheat grains and quality properties of wheat flour

Mechanistic insights into starch behavior and starch-protein interactions in whole grain oat flour: Structural and functional modifications by steam explosion treatment

This study explores the effects of steaming, roasting, and steam explosion treatment on the structural, rheological, and functional properties of whole grain oat flour, with a particular focus on starch changes and starch-protein interactions. Steam explosion treatment altered the physicochemical properties of whole grain oat flour, evidenced by changes in color parameters (L* from 70.9 to 67.4, WI from 58.6 to 54.4), degree of gelatinization (increased from 21.4 % to 89.9 %), and gel network stability. Notably, steam explosion treatment uniquely disrupted starch crystallinity and reduced amylopectin content (40.8 % to 31.1 %). Microscopic analysis (scanning electron microscopy, confocal laser scanning microscopy) and multi-scale structural characterization (infrared spectroscopy, differential scanning calorimetry) revealed that the oat starch-protein mixture exhibited a three-dimensional cellular network, with significantly increased hydrogen bonding between starch and protein. This interaction formed a cross-linked gel network structure, enhancing gel strength, water retention, and thermal stability while delaying starch retrogradation, ultimately improving the shelf life of oatmeal porridge. Mechanistic analysis revealed that steam explosion treatment enhanced water molecule binding to macromolecules, mitigating water migration and structural degradation during storage. This research provides new insights into the molecular interactions underpinning whole oat processing, offering a foundation for the development of high-quality whole oat-based products.

Elucidation on the quality improvement of dumpling wrappers by glycosylated potato protein under freeze-thaw cycle treatment

Dumplings are the favorite quick-frozen food for people in many countries. However, the formation and recrystallization of ice crystals damage the quality of dumpling wrappers during storage. Research has shown that proteins and polysaccharides can improve the quality of frozen dough and that the Maillard reaction can improve the functional properties of proteins and polysaccharides. Therefore, the effects of glycosylated protein between potato protein and xanthan gum (PXM) on the overall changes in dumpling wrappers during freeze-thaw cycles (FT) were studied in this study. The results showed that the addition of PXM (1 %) slowed the deterioration of texture and rheological properties and reduced the cooking loss rate and freezable water content of dumpling wrappers during FT, thus improving the texture quality of dumpling wrappers. Moreover, the addition of PXM delayed the changes in the contents of free sulfhydryl (SH) and disulfide (SS) bonds during storage, weakening the damage to the secondary structure and network structure of the protein. The reason for this difference may be that protein glycosylation significantly increases the zeta potential (13.5 %), surface hydrophobicity (63.9 %), emulsifying activity (192.6 %) and emulsification stability (116.7 %) of potato protein (PP). These results suggest that the application of the glycosylated protein provides a potentially feasible approach to improve the quality of frozen dumpling.

Enhancement of dietary fiber yoghurt using high-pressure homogenized bacterial cellulose: Effects on microstructure, water distribution, and sensory properties

In this study, bacterial cellulose (BC) was first treated with high-pressure homogenization (HPH), which effectively dispersed the BC fiber network and enhanced its sodium cholate adsorption capacity (0.28 ± 0.06 mL/g). Subsequently, BC was used as a dietary fiber source, mixed with raw cow's milk, subjected to HPH, and fermented to produce yoghurt. Results showed that BC yoghurt (C2), prepared at 10,000 rpm and 800 bar, exhibited improved water binding capacity, reduced free water content, and particle size distributions of D10 = 3.29 μm, D50 = 8.78 μm, and D90 = 22.31 μm. Scanning electron microscopy revealed that BC in C2 tightly bound to casein micelles, effectively filling whey pores. Textural analysis indicated that C2 had higher hardness, adhesiveness, and resilience. Color analysis demonstrated a brightness L* of 97.74 ± 0.87, indicating optimal color properties. During storage, C2 yoghurt maintained desired pH and acidity levels, with significantly higher water-holding capacity (68.67 ± 1.00 %, p < 0.05). Sensory evaluation confirmed its excellent organoleptic properties and high acceptance. In conclusion, HPH-treated yoghurt (10,000 rpm, 800 bar) provides a valuable reference for developing functional yoghurt products.

Strategy for Enhancing Wheat Drying Efficiency and Flour Quality: Hybridization of Tempering and Hot Air Drying

The moderate processing of wheat is increasingly valued. One of the technological means to achieve moderate processing is the hybridization of tempering and hot air drying for postharvest wheat. The initial moisture content at onset of tempering (IMCOT) of wheat significantly influences the efficiency of hot air drying as well as the yield and quality of wheat flour. This study investigates the effects of varying IMCOT and tempering durations on the drying characteristics of wheat, the flour yield, the flour properties, and the properties of flour slurries. The findings revealed that tempering treatments reduced the drying time and altered the pasting characteristics of the flour slurries. This phenomenon could be attributed to the alteration of the kernel structure and starch destruction caused by tempering treatment. Tempering significantly (P < 0.05) affected the protein content and wet gluten content of wheat flour (WF). For the effect of IMCOT, the shortest drying time (35 min) was observed at an IMCOT of 0.17 g/g d.b., while the highest wet gluten content of WF was achieved when it was 0.19 g/g d.b. The lowest breakdown value (908.00 Brabender Units, BU) and highest setback value (811.50 BU) of WF were observed at an IMCOT of 0.19 g/g d.b. For the effect of tempering duration, the shortest drying time (35 min) was achieved at a tempering duration of 40 min. Tempering duration improved the whiteness and brightness of the flour, as well as increased its protein content. Considering the drying efficiency and the quality attribute, the optimal tempering condition was the IMCOT of 0.19 g/g d.b. and a tempering duration of 40 min.

Effects of the hot air roasting process on brown rice moisturized by water-spraying method

The hard texture of brown rice, attributed to its bran layer, poses significant challenges in improving its palatability. This study investigated the effects of hot-air roasting on the morphological characteristics, thermal properties, and water absorption of brown rice, moisturized using a water-spraying method to enhance texture. Moisture-controlled roasting resulted in a significant difference in the L* values, with the highest observed at 20 % water content. The extent of cracking and fine fissure formation varied with roasting temperature, resulting in increased water absorption. These structural changes subsequently influenced the tan δ value, hardness, and stickiness in the rheological analysis post-cooking. The gelatinization degree significantly increased with higher roasting temperatures and retrogradation effects were noted at 130 °C and 150 °C with a 15 % water content during cooking. Texture and sensory evaluations confirmed an increase in hardness as retrogradation progressed. The observed changes in this study have a profound impact on the textural and sensory attributes of the final cooked product.

Dynamic behaviors of protein and water associated with fresh noodle quality during processing based on different HMW-GSs at Glu-D1

In this study, dynamic behaviors of proteins and water during fresh noodles processing associated with the quality of fresh noodles were systematically investigated by using wheat near-isogenic lines carrying high-molecular-weight glutenin subunits (HMW-GS) 2 + 12, 3 + 12 or 5 + 10 at the Glu-D1 locus. The results showed that subunits 5 + 10 tend to form a complex gluten network and had a poorly hydrated ability, that prevent the intrusion of external water during cooking; subunits 3 + 12 formed a moderate strength gluten network that generated a medium ability to resist the hydrated and mechanical treatment, which explained the highest water absorption and less cooking loss of cooked noodles; while subunits 2 + 12 formed fragile protein aggregates that had a poor ability to resist mechanical. The findings demonstrated that subunits 3 + 12 provided a suitable gluten network which was crucial for intrusion and hydration of external water thus formed a uniform gluten network and excellent fresh noodle quality.

Influence of roasted flaxseed marc flour on rheological, structural, fermentation, water distribution, and migration properties of wheat dough

Roasted flaxseed (RF) marc, which is a by-product obtained from RF oil extraction, has high nutritional value. This study evaluated the impact of RF marc flour on rheological, structural, fermentation, water distribution, and migration properties of the wheat dough. Results showed that adding RF into wheat flour (WF) could effectively increase the water absorption in the dough and retard the retrogradation of starch. The fermentation results revealed that adding RF could improve the gas retention coefficient of dough. Compared to the dough prepared with WF, the doughs enriched with RF had higher tan δ values (ratio of loss modulus G″ to storage modulus G'), indicating a more liquid-like property. The mobility of tightly bound and free water in dough was decreased by adding RF, whereas the distribution of free water was increased. On the one hand, adding RF would dilute the gluten content in dough, resulting in a weaker protein network. On the other hand, the dietary fiber and proteins in RF could offset the gluten dilution effect to some extent. Overall, the results suggested that the substitution level of RF in WF should be below 25% to avoid serious dough quality deterioration, and the RF-WF blended flour could be a potential ingredient to produce wheat products with moist taste. These findings could be useful for guiding the future usage of RF marc in wheat-based products.

Comparison of milling methods on the properties of common buckwheat flour and the quality of wantuan, a traditional Chinese buckwheat food

The microstructural and techno-functional properties of buckwheat flour and its processability for making wantuan, as affected by different milling methods, were investigated. Results showed that the particle sizes (d(0.5)) of the flours made by stone-milling (SM), hammer-milling (HM), laboratory grinding with steaming pretreatment for 5 min (LG-5) and 10 min (LG-10) were 95.5, 111.5, 35.4 and 41.1 μm, respectively. Moreover, SM and HM flours had less liberated starch granules and 20.84%-24.32% higher relative crystallinity than LG-10 flour. Slurries of laboratory-grinded flours showed excellent suspension stability. LG-10 flour had lowest pasting viscosities but greatest storage modulus and loss modulus. Color differences among the wantuan made from different flours were not visibly perceived (ΔE < 5). Wantuan made from LG-5 flour exhibited highest textual quality due to its greatest resilience (0.376), good springiness (0.933) and accepted chewiness (1093.31). Concluding, steaming prior to grinding could improve the qualities of buckwheat flour for wantuan making.

Occurrence of Antibiotic Resistant Bacteria in Flours and Different Plant Powders Used in Cuisine

In recent years, several alimentary diseases have been connected with the consumption or tasting of raw flour and dough. Microbiological quality concern is also raising due to increased consumer demand for plant powders, while some of them can be consumed without prior thermal processing. In this study, we have focused on the occurrence of antibiotic-resistant coliform bacteria and enterococci in flour, plant powder and dough from Slovak retail. Our results indicated the presence of both total and antibiotic-resistant coliform bacteria and enterococci in the flour and powder samples. Lower numbers of the total, as well as resistant bacteria, were detected in flours compared to plant powders. Coliform bacteria isolates were predominantly identified as Klebsiella spp. and Enterobacter spp. Ampicillin resistance appeared in 97% of isolates followed by chloramphenicol resistance (22%) and tetracycline resistance (17%). The presence of the bla_SHV gene was confirmed in 13% of isolates. The tetA and tetE genes were present in 25% of isolates of coliform bacteria. The presence of enterococci was detected only in plant powders. Antibiotic-resistant strains were identified as the following: Enterococcus casseliflavus, E. gallinarium and E. faecium. Despite the isolates showing resistance to vancomycin, the presence of the vanA gene was not detected. The majority of antibiotic-resistant isolates belonged to the group of medium biofilm producers. None of these isolates showed efflux pump overproduction. Antibiotic-resistant coliform bacteria and enterococci were not detected in the processed doughs.

Effect of Tempering Conditions on White Sorghum Milling, Flour, and Bread Properties

The effects of room temperature water, hot water, and steam tempering methods were investigated on sorghum kernel physical properties, milling, flour, and bread-making properties. Overall tempering condition and tempering moisture content were found to have a significant effect on the physical properties. Milling properties were evaluated using a laboratory-scale roller milling flowsheet consisting of four break rolls and eight reduction rolls. Room temperature tempering (18% moisture for 24 h) led to better separation of bran and endosperm without negatively impacting flour quality characteristics i.e., particle size distribution, flour yield, protein, ash, damaged starch, and moisture content. Bread produced from the flour obtained from milling sorghum kernels tempered with room temperature water (18% m.c for 24 h) and hot water (16% m.c at 60 °C for 18 h) displayed better bread-making properties i.e., high firmness, resilience, volume index, higher number of cells, and thinner cell walls when compared to other tempering conditions. Room temperature water tempering treatment (18% m.c for 24 h) could be a better pretreatment process for milling white sorghum kernels without negatively impacting the flour and bread-making quality characteristics.