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Summary: Wheat tempering conditions grains before a milling process begins. Process adjustments must be made to reach a desired level of flour quality and yield, depending on multiple factors. This article aims to develop a decision support tool to help operators adjust the first‐stage tempering parameters. It is based on a regression model that predicts an increase in organic wheat moisture content according to the properties of the wheat (initial wheat moisture content, wheat protein content and wheat temperature), process parameters (targeted wheat moisture content, wheat flow rate, water flow rate, wheat quantity and resting time) and tempering conditions (water quantity, average day temperature and average day humidity). The increase in wheat moisture achieved during the first tempering stage varies between 0% and 5%. Five regression models were compared: OLS, LASSO, RIDGE, ElasticNet and XGBoost. The models have been developed and tested from a case study at an organic wheat mill. The results indicate that the LASSO model outperformed others, with an average prediction error of 0.428%. The model showed the importance of humidity and temperature factors during the tempering process. The flow of water and wheat were the most influential parameters for an increase in wheat moisture content. [ABSTRACT FROM AUTHOR]

Wheat tempering is an important step in wheat milling process. Appropriate tempering method is beneficial to shorten tempering time, reduce microbial content, improve the quality of flour and by-products, reduce energy consumption and save production cost. However, tempering process is often affected by multiple factors such as raw grain varieties, water quality, water addition, time, temperature, season and climate. At present, wheat flour processing enterprises are facing technical problems such as uneven tempering and easy breeding of microorganisms in the tempering process. In this paper, the basic principle of wheat tempering and the effects of raw grain, water addition, different temperature and humidity, time and other factors on wheat tempering were introduced in detail. The effects of different tempering methods such as heat treatment, vibration, ultrasound, vacuum, fracturing damage, biological enzyme preparation, salt water, acid water and other sterilization treatment on wheat processing and product quality were emphatically expounded. The advantages and disadvantages of different tempering methods and their application in current domestic production were also summarized in order to provide reference for wheat milling enterprises. Finally, it is pointed out that further research should be carried out on the accurate calculation and regulation of water content and the combination of different tempering methods and its effects on flour application quality for different wheat varieties.

Slightly acidic electrolyzed water (SAEW) was prepared and used as wheat tempering water. This study explored the impacts of tempering with SAEW on microbial load and diversity and quality properties of wheat flour. As SAEW volume ratio increased, the residual level of total plate counts (TPC) and mould/yeast counts (MYC) decreased dramatically (p < 0.05). Based on genomics analysis, bacterial 16S rRNA gene and fungal ITS1 gene region were performed to characterize the changes in microbial communities' composition and diversity in response to SAEW treatment. SAEW optimal volume ratio (6.5:10, v/v) of SAEW with distilled water influenced wheat microbiome composition, with a higher microbial diversity and abundance discovered on the control grains. Bacteroidetes of predominant bacterial phylum and Ascomycota of the most abundant fungal phylum were reduced after SAEW optimal volume ratio tempering. The flour yield is higher and ash content is lower than the control samples. Falling number and "b*" in terms of colour markedly increased. DSC (Differential Scanning Calorimetry) test showed that To (onset temperature), Tp (peak temperature), and Tc (conclusion temperature) were significantly decreased in thermal characteristics of flour. Gluten content, protein content, ΔH and pasting properties tests showed no significant change. It can be concluded that SAEW should be applied on wheat tempering for producing clean wheat flour. ANOVA and Tukey's honestly significant difference (HSD) test were used for the analysis of variance and differences between the experimental and control groups, with p < 0.05. [ABSTRACT FROM AUTHOR]

Deoxynivalenol (DON) in wheat (Emai596) was degraded by five ways of ozone treatments, including ozone-gas treated wheat flour, wheat kernels before and after tempering, and tempering and washing with ozonated-water. For lab-scale milling, the effect on flour quality was investigated. The DON was quantified via high-performance liquid chromatography after extraction with immunoaffinity columns. The measure indicated all treatments could decrease the DON content of flour below 1.00 mg/kg. Ozone-gas treated wheat kernels after tempering had the highest DON degradation rate 33.33%. Ozonation produced no significant difference in gluten qualities, dynamic viscoelasticity, pasting and mixing properties, when wheat kernels were treated with ozone-gas or ozonated-water. Although ozone-gas treated flour had the highest whiteness (85.56), but it had negative effect on the rest of quality indicators. The results suggested the treatment of Ozone-gas treated tempered wheat kernels could not only degrade DON most efficiently but also ensure quality of flour.

Slightly acidic electrolyzed water (SAEW) was prepared and used as wheat tempering water. This study explored the impacts of tempering with SAEW on microbial load and diversity and quality properties of wheat flour. As SAEW volume ratio increased, the residual level of total plate counts (TPC) and mould/yeast counts (MYC) decreased dramatically (p < 0.05). Based on genomics analysis, bacterial 16S rRNA gene and fungal ITS1 gene region were performed to characterize the changes in microbial communities’ composition and diversity in response to SAEW treatment. SAEW optimal volume ratio (6.5:10, v/v) of SAEW with distilled water influenced wheat microbiome composition, with a higher microbial diversity and abundance discovered on the control grains. Bacteroidetes of predominant bacterial phylum and Ascomycota of the most abundant fungal phylum were reduced after SAEW optimal volume ratio tempering. The flour yield is higher and ash content is lower than the control samples. Falling number and “b*” in terms of colour markedly increased. DSC (Differential Scanning Calorimetry) test showed that To (onset temperature), Tp (peak temperature), and Tc (conclusion temperature) were significantly decreased in thermal characteristics of flour. Gluten content, protein content, ΔH and pasting properties tests showed no significant change. It can be concluded that SAEW should be applied on wheat tempering for producing clean wheat flour. ANOVA and Tukey’s honestly significant difference (HSD) test were used for the analysis of variance and differences between the experimental and control groups, with p < 0.05.

Deoxynivalenol (DON) in wheat (Emai596) was degraded by five ways of ozone treatments, including ozone-gas treated wheat flour, wheat kernels before and after tempering, and tempering and washing with ozonated-water. For lab-scale milling, the effect on flour quality was investigated. The DON was quantified via high-performance liquid chromatography after extraction with immunoaffinity columns. The measure indicated all treatments could decrease the DON content of flour below 1.00 mg/kg. Ozone-gas treated wheat kernels after tempering had the highest DON degradation rate 33.33%. Ozonation produced no significant difference in gluten qualities, dynamic viscoelasticity, pasting and mixing properties, when wheat kernels were treated with ozone-gas or ozonated-water. Although ozone-gas treated flour had the highest whiteness (85.56), but it had negative effect on the rest of quality indicators. The results suggested the treatment of Ozone-gas treated tempered wheat kernels could not only degrade DON most efficiently but also ensure quality of flour. [ABSTRACT FROM AUTHOR]

Background and objectives: In recent years, special concern has been raised about the safety of wheat‐based products. In light of several incidents of foodborne illness associated with flour, the objectives of this study were designed to (a) evaluate the efficacy of saline organic acids solutions to reduce the natural microbiota of soft wheat grain and flour, and (b) to assess the impact of these tempering solutions on the functional properties of soft wheat flour. Findings: The microbial load of the tempered wheat was significantly reduced by all saline organic acid treatments. The combination of 5.0% lactic acid–NaCl was the most effective against aerobic mesophilic bacteria and Enterobacteriaceae, with average reductions of 3.1 ± 0.1 and 4.5 ± 0.0 log CFU/g, respectively. In addition, this tempering solution yielded flour with a significantly lower microbial load compared with the control. Tempering with saline organic acid solutions did result in minor, but significant, variations in the solvent retention capacity profile of some flours. However, the treatments did not cause significant changes in the pasting profile of flours or in the physical characteristics and texture profile of baked cookies. Conclusions: The addition of organic acids and NaCl to the tempering water improved the microbiological quality of the wheat grain and the resulting flour without compromising its functionality. Significance and novelty: This study evaluates the inclusion of antimicrobial agents in the water used to temper wheat grain prior to milling as a practical method to reduce the number of microbial contaminants in flour and flour‐based foods that are at risk for consumption without cooking or any killing step. [ABSTRACT FROM AUTHOR]

The occurrence of recalls involving pathogenic Escherichia coli-contaminated wheat flours show the need for incorporating antimicrobial interventions in wheat milling. The objectives of this study were to assess the efficacy of sodium bisulfate (SBS) tempering in reducing E. coli O121 (ATCC 2219) and O26 (ATCC 2196) wheat load and to evaluate the impact of effective (≥3.0 log reductions) SBS treatments on wheat flour quality. Wheat grains were inoculated with E. coli (~6 log CFU/g) and tempered (17% moisture, 24 h) using the following SBS concentrations (%wheat basis): 0, 0.5, 0.75, 1.0, 1.25, and 1.5% SBS. Reductions in E. coli O121 and O26 wheat load at different time intervals (0.5, 2, 6, 12, 18, and 24 h) during tempering were evaluated. The addition of SBS during tempering resulted in E. coli (O121 and O26) log reductions of 2.0 (0.5% SBS) to >4.0 logs (1.5% SBS) (p ≤ 0.05). SBS tempering (1.25 and 1.5% SBS) produced acidic wheat flours (pH = 4.51–4.60) but had comparable wheat flour properties in terms of composition, dough, and bread-making properties relative to the control (0% SBS). SBS tempering reduced the E. coli O121 and O26 load of wheat after tempering with minimal effects on wheat flour quality.

The effects of tempering with phosphoric acid (PA) and potassium carbonate (PC) solutions on the microbial load and the quality of wheat flour and fresh noodles (FNs) were studied. With the increase of PA/PC concentration, total plate count (TPC) and mold and yeast count (MYC) of tempered wheat kernels and flour streams decreased significantly (p < 0.05), and 3B and 3M flour streams had the greatest microbial reduction. PA/PC tempering had little effect on grinding characteristics of wheat kernels. Specifically, the whiteness of the obtained straight-grade flour increased and polyphenol oxidase (PPO) activity decreased significantly (p < 0.05) and the pH and acidity changed slightly. RVA and Mixolab showed that the pasting viscosity decreased slightly after PA tempering, and the protein strength increased slightly after PC tempering. The initial microbial quantity and browning rate of FNs made from flour obtained from wheat tempered with PA/PC solutions decreased significantly (p < 0.05) and the texture characteristics of FNs were significantly enhanced (p < 0.05). The results showed that tempering with PA/PC solutions could effectively reduce the microbial content of flour streams without detrimental effects on the quality of flour and FNs. [Display omitted] • PA/PC tempering reduced the microbial load of tempered wheat kernels and six flour streams. • PA/PC tempering was more effective for microbial reduction of 3B and 3M flour streams. • PA/PC tempering reduced PPO activity of bran and flour and increased the whiteness of flour. • PA/PC tempering reduced the initial microbial load and browning rate of fresh noodles. • PC tempering improved the dough structure of flour and texture properties of fresh noodles. [ABSTRACT FROM AUTHOR]

[Display omitted] • PAW was used to replace pure water in the traditional tempering process. • Tempering with PAW can be used to degrade DON in wheat. • Tempering with PAW efficiently inactivated the microorganisms of wheat grains. • Tempering with PAW has no significant impact on wheat quality except vitamin E. Deoxynivalenol (DON) is prevalent in wheat and threatens the health of humans and animals. It has been certificated that plasma activated water (PAW) can effectively degrade DON in wheat. However, the application of PAW used in the production of wheat flours was not reported nowadays. Thus, PAW was used to replace pure water in the traditional tempering process to eliminate DON in wheat, and DON degradation effect of PAW was compared with H 2 O 2 and O 3. The DON degradation rate was 58.78 % by tempering for 24 h with PAW prepared at 50 kV for 10 min. The H 2 O 2 and O 3 were found to be critical contributors in PAW for DON degradation. Afterwards, effects of PAW on microorganism inactivation and wheat qualities were studied. After tempering with PAW, the bacterial and fungal counts, the number of surviving Fusarium graminearum in wheat were decreased significantly. Moreover, no negative effects were observed except a slight decrease in vitamin E content. Therefore, tempering with PAW can be a promising strategy to control DON pollutant in wheat. [ABSTRACT FROM AUTHOR]

Nonthermal plasma-activated water (PAW) was prepared and used as wheat tempering water. The effects of tempering with PAW on total plate count and quality properties of wheat flour streams were studied. With the extension of plasma activation time, the content of NO 3 −, NO 2 − and H 2 O 2 in PAW significantly increased, and pH decreased dramatically (p < 0.05). After tempering with PAW activated for 40 min, total plate counts in bran, low-grade and patent flour were significantly decreased by 68.85%, 60.91% and 27.27%, respectively (p < 0.05). The polyphenol oxidase, lipase and lipoxygenase activities in low-grade flour markedly decreased by 41.27%, 18.07% and 31.42%, respectively, with the treatment of PAW (p < 0.05). Rapid Visco Analyzer results showed a decrease in peak, trough and final viscosity of straight-grade flour. The free sulfhydryl content in straight- and low-grade flour also decreased. Mixolab test showed there was no significant change in dough rheological characteristics of straight-grade flour. Overall, tempering with PAW could be a promising nonthermal technique to decrease the microbial loads of flour without obvious detrimental effects on its processing quality. [Display omitted] • PAW was used as tempering water to reduce microbial loads of flour streams. • Tempering with PAW inhibited the enzymes activity in bran and low-grade flour. • Tempering with PAW reduced the paste viscosity and free sulfhydryl content of flour. • Tempering with PAW could maintain the processing properties of flour. [ABSTRACT FROM AUTHOR]

The occurrence of recalls involving pathogenic Escherichia coli -contaminated wheat flours show the need for incorporating antimicrobial interventions in wheat milling. The objectives of this study were to assess the efficacy of sodium bisulfate (SBS) tempering in reducing E. coli O121 (ATCC 2219) and O26 (ATCC 2196) wheat load and to evaluate the impact of effective (≥3.0 log reductions) SBS treatments on wheat flour quality. Wheat grains were inoculated with E. coli (~6 log CFU/g) and tempered (17% moisture, 24 h) using the following SBS concentrations (%wheat basis): 0, 0.5, 0.75, 1.0, 1.25, and 1.5% SBS. Reductions in E. coli O121 and O26 wheat load at different time intervals (0.5, 2, 6, 12, 18, and 24 h) during tempering were evaluated. The addition of SBS during tempering resulted in E. coli (O121 and O26) log reductions of 2.0 (0.5% SBS) to >4.0 logs (1.5% SBS) ( p ≤ 0.05). SBS tempering (1.25 and 1.5% SBS) produced acidic wheat flours (pH = 4.51-4.60) but had comparable wheat flour properties in terms of composition, dough, and bread-making properties relative to the control (0% SBS). SBS tempering reduced the E. coli O121 and O26 load of wheat after tempering with minimal effects on wheat flour quality.

• This paper presents a new technology for low bacterial wheat flour production. • Tempering with steam greatly shortened the tempering time of wheat grains. • Tempering with steam reduced the microbial load in tempered grains and wheat flour. • Tempering with steam changed grinding properties of wheat grains. • Tempering with steam improved the rheological properties of wheat flour. In this study, the effects of tempering with steam on the water distribution of wheat grains and the microbial load in wheat flour were investigated, as well as the physicochemical properties of wheat flour. Results showed that when steam treatment time was 320 s, the total plate count (TPC), yeast and mold count (YMC), and mesophilic aerobic spores (MAS) in flour decreased by 1.74, 1.99 and 1.01 lgCFU/g, respectively. Nuclear magnetic resonance (NMR) results showed that tempering with steam accelerated the water distribution of grains and significantly (p < 0.05) shortened the tempering time. Moreover, flour yield, particle size, ash content, and damaged starch content of flour were all altered. Furthermore, after tempering with steam, proteins were aggregated and starches were partially gelatinized, which caused dough development time and stability of flour increasing. Collectively, our findings indicated steam tempering could shorten the tempering time and improve the qualities of flour partly. [ABSTRACT FROM AUTHOR]

As a raw agricultural commodity, wheat is exposed to microbial contamination; therefore, enteric pathogens may be among its microbiota creating a food safety risk in milled products. This research evaluates (1) the effectiveness of organic acids dissolved in saline solutions to reduce the counts of pathogenic microorganisms in soft and hard wheat, and also investigates the effect of seasonal temperature on (2) survivability of pathogens in wheat kernels and on (3) pathogen inactivation during tempering with saline organic acid solutions. Wheat samples were inoculated with cocktails of either 5 serovars of Salmonella enterica , 5 E. coli O157:H7 or 6 non-O157 Shiga toxin-producing E. coli (STEC) strains to achieve a concentration of ~7 log CFU/g. Inoculated samples were allowed to stand for 7-days at temperatures (2.0, 10.8, 24.2, 32 °C) corresponding to those experienced during winter, spring/fall, and summer (average and maximum) in the main wheat growing regions in the state of Nebraska, USA. Besides water, solutions containing acid (acetic or lactic 2.5% or 5.0% v/v) and NaCl (~26% w/v) were used for tempering the wheat to 15.0% (soft) and 15.5% (hard) moisture at the different seasonal temperatures. The survival of pathogenic microorganisms throughout the resting period, and before and after tempering was analyzed by plating samples on injury-recovery media. The survival rate of pathogenic microorganisms on wheat kernels was higher at temperatures experienced during the winter (2.0 °C) and spring/fall (10.8 °C) months. Regardless of tempering temperature, the initial pathogen load was reduced significantly by all solutions when compared to the control tempered with water (P ≤.05). The combination of lactic acid (5.0%) and NaCl was the most effective treatment against Salmonella enterica , E. coli O157:H7 and non-O157 STEC, with average reduction values of 1.8, 1.8 and 1.6 log CFU/g for soft wheat and 2.6, 2.4 and 2.4 log CFU/g for hard wheat, respectively. Implementation of organic acids and NaCl in tempering water may have the potential to reduce the risk of pathogen contamination in milled products. Unlabelled Image • Winter and fall temperatures favor the survival of enteric pathogens in wheat. • Tempering temperatures did not impact the efficacy of the saline organic acid solutions. • Lactic acid was more effective than acetic acid at reducing pathogen load. • Pathogens were reduced by 1.7 and 2.5 log CFU/g in soft and hard wheat, respectively. [ABSTRACT FROM AUTHOR]