Progress 10/10/14 to 09/30/18
Outputs
Target Audience:Food manufacturers, food product developers, plant breeders Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Two PhD students received research training as a result of this project. How have the results been disseminated to communities of interest?Results have been disseminated in peer-reviewed publications and in scientific meetings. They have also been shared in workshops, meetings with food companies, and in individual discussions. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
The broad objectives of the NC-213 Multistate Project are to: 1) characterize quality and safety attributes of cereals, oilseeds, and their processed products, and to develop related measurement systems; 2) develop efficient operating and management systems that maintain quality, capture value, and preserve food safety in the farm-to-user supply chain; and 3) be a multiinstitutional framework for the creation of measurable impacts generated by improvements in the supply chain that maintain quality, increase value, and protect food safety/security. Our group's contribution to this project was on objective 1. Our specific objectives were to: 1) improve the microbial safety of wholegrain and straight-grade flours by conditioning wheat with different combinations of organic acids and salt or by steam-treatment prior to milling; 2) determine functional and sensorial properties of products made from wholegrain and straight-grade flours that were conditioned with combinations of organic acids and salt or steam-treatment prior to milling; 3) determine the efficacy of conditioning wheat with different combinations of organic acids and salt or treating with steam at prolonging the shelf life of wheat flours--especially wholegrain flours; 4) determine the variation in asparagine concentration in Nebraska wheat to determine conditions that will reduce free asparagine and thus acrylamide-forming potential in wheat-based foods. This project will reduce incidents of food borne illness, improve safety, and maintain consumer confidence in wheat-based products and keep the Nebraska agricultural and food industries strong. First, a survey was performed to determine the microbial contamination of wheats produced in Nebraska. In the first season, aerobic plate count (APC), Enterobacteriaceae (Eb), yeasts and molds, and internal mold infection (IMI) were significantly lower in grain samples collected from Panhandle as compared to grain harvested from the South Central and Southeastern districts. No significant differences in the yeast counts were found in grain collected from all districts in the second year, but levels of IMI and mold counts were significantly higher in the Southeastern district as compared to the Panhandle district. Deoxynivalenol was detected in all districts, but was below the advisory level of 1 mg/kg for processed wheat. In general, microbial load in wheat grain tended to be lower in those areas with lower relative humidity (below 65%) and with temperatures of less than 13.7°C and greater than 31.5°C. These results were published in a peer-reviewed journal. The results from this project may impact grain buyers and processors. For these individuals relative humidity and temperature following wheat flowering should be used as an additional parameter when selecting grain for higher microbiological safety. A microbial survey was also conducted in a pilot scale flour milling facility to determine microbial loads and microbial distribution across the milling equipment. Pathogens were detected at very low levels and microorganisms tended to concentrate in the equipment used to sort and clean wheat kernels prior to milling, on the break rolls, and on the screw conveyors that carry the final milled products. Further data analysis is still being carried out including a quantitative microbial risk assessment (QMRA) to evaluate the impact of the milling process on the ultimate safety of milling end products. The QMRA model will simulate the steps followed by grain after harvesting, from entering the milling system to the end product (i.e. flour or flour-based products). The model will be developed to evaluate the public health risks associated with the consumption of wheat-based products contaminated with E. coli O157:H7, Salmonella, and non-O157 STEC in the United States. The findings of this project will lead to better decision-making regarding strategies that could be applied throughout the wheat milling process to reduce microbial contamination and safeguard consumers. Next, the efficacy of adding organic acids and NaCl to tempering water to reduce microbial contamination in wheat was evaluated. The combination lactic acid (5.0%) and NaCl (52%) was the most effective at reducing aerobic plate count and Enterobacteriaceae, with an average reduction of 4.3 and 4.7 log CFU/g, respectively, in hard wheat, and 3.1 and 4.5 log CFU/g, respectively, in soft wheat. The best combination for reducing Salmonella enterica were achieved using lactic acid 5%+NaCl 26% solution at 2?C, which resulted in 2.1 log CFU/g reduction. These treatments did not affect functionality of straight-grade flours milled from both hard and soft wheats. The treatment did change hard whole wheat flour functionality slightly but significantly. These results were published in several peer-reviewed journal articles. Implementation of saline organic acid tempering prior to milling wheat could benefit the milling industry and consumers by preventing or reducing the risk of pathogen contamination in milled products. In a related project, steaming of wheat kernels prior to milling was assessed to determine the effects on storage stability of whole wheat flour and on microbial load of wheat flour. Steam-treatment of wheat four up to 90 s reduced microbial load of flour and improved lipid stability of whole wheat flour. This treatment may be used alone or in combination with saline organic acid treatment to further improve the microbial safety of wheat flour or improve stability of whole grain flours. The variation in asparagine concentration in Nebraska wheat was measured because asparagine can be converted to acrylamide, a toxic compound, during baking of wheat products. We found that the major differences in asparagine concentration were due to growing environment, although the cultivar Freeman may be a low asparagine accumulating genotype. We also found that delayed harvest leads to higher asparagine accumulation in wheat kernels. This information may be used to produce wheats with lower levels of free asparagine and thus produce safer baked wheat products. In the final year of this project, we initiated a project on creating germinated wheat flour in collaboration with a large milling company. In this project we found that the phytic acid, thiamine, and dough strength of whole grain flour from germinated wheat decreased, whereas lysine, asparagine, GABA, lipase, esterase, and lipoxygenase activities increased compared with flour from ungerminated wheat. A small but significant effect of drying temperature was observed for asparagine, GABA, dough strength, and lipase and esterase activities. Drying temperature did not show any differences when the grains were germinated for up to 48 h. Whole grain flour from germinated wheat was added to ungerminated whole wheat flour at 2, 5, and 10 % (flour basis). Doughs and breads made from these composite flours had improved mixing properties, loaf volume, and firmness, except at the highest proportions and from longer germination times. This study is being used to develop commercial germinated whole wheat flours.
Publications
- Type:
Journal Articles
Status:
Accepted
Year Published:
2018
Citation:
Navrotskyi S, Beanziger PS, Regassa T, Guttieri MJ, Rose DJ. Variation in asparagine concentration in Nebraska wheat. Cereal Chemistry in press.
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Poudel R, Bhatta M, Regassa T, Rose DJ. 2017. Influence of foliar fungicide treatment on lipolytic enzyme activity of whole wheat. Cereal Chemistry 94:633-639.
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Sabill�n L, Bianchini A, Stratton J, Rose DJ. 2017. Effect of saline organic acid solutions applied during wheat tempering on flour functionality. Cereal Chemistry 94:502-507.
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Sabill�n L, Stratton J, Rose DJ, Flores RA, Bianchini A. 2016. Reduction in microbial load of wheat by tempering with organic acid and saline solutions. Cereal Chemistry 93:638-646.
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Sabill�n, L, Stratton J, Rose DJ, Regassa TH, Bianchini A . 2016. Microbial load of hard red winter wheat produced at three growing environments across Nebraska, USA. Journal of Food Protection 79:646-654.
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Progress 10/01/16 to 09/30/17
Outputs
Target Audience:Food manufacturers, food product developers, plant breeders Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Two graduate students received research training as a result of this project. How have the results been disseminated to communities of interest?Results have been disseminated in peer-reviewed publications and in scientific meetings. They have also been shared in workshops, meetings with food companies, and in individual discussions. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Cereals are important staple foods in the American diet. As staple foods, it is important that these foods be free of both microbial and chemical hazards and have sufficient shelf-life. The recent incidence of foodborne disease outbreaks caused by products containing flour has highlighted the fact that flour can be a source of microbial hazards. Examples of chemical hazards in cereal products include free asparagine, a precursor to acrylamide in baked products. Finally, whole wheat flour is subject to lipid degradation during storage that renders the flour rancid and not usable for human food. These three issues were addressed in this reporting year. This reporting year, our research on wheat microbial safety has resulted in current and potential impacts. Our group met with several milling companies that are testing our saline organic acid tempering and our steam-treatment processes on pilot scales in their facilities. We have previously shown that these treatments are effective in reducing microbial load in wheat flour. We expect that the implementation of these treatments in commercial production of wheat flour will reduce the risk of food borne illness outbreaks caused by consuming raw wheat flour. In our project on free asparagine in wheat flour we found that delayed harvest leads to higher asparagine accumulation in wheat kernels. In future years we will share this information with producers to reduce free asparagine in wheat and thus reduce the potential for acrylamide in wheat-based foods. The broad objectives of the NC-213 Multistate Project are to: 1) characterize quality and safety attributes of cereals, oilseeds, and their processed products, and to develop related measurement systems; 2) develop efficient operating and management systems that maintain quality, capture value, and preserve food safety in the farm-to-user supply chain; and 3) be a multiinstitutional framework for the creation of measurable impacts generated by improvements in the supply chain that maintain quality, increase value, and protect food safety/security. Our group's contribution to this project was on objective 1. No contributions to objectives 2 and 3 were made during the reporting year. Two projects were completed under this objective. In the first project, the variation in asparagine concentration was measured in Nebraska wheat. Acrylamide, a toxic compound, can be formed from asparagine during baking of wheat products. Three widely grown wheat cultivars ('Goodstreak', 'Camelot', 'Freeman') and seven experimental lines were grown at five locations in 2014. Due to the large environmental effect on asparagine concentration, the named cultivars were also evaluated at twelve locations in 2016. Asparagine concentration varied widely among samples (200-1100 mg/kg). In 2014, the highest concentration of asparagine was measured in samples grown at a location where delayed harvest resulted in excess solar radiation. In 2016, the highest asparagine concentration was measured in wheat grains grown in a location that experienced high disease pressure. In pairwise comparisons among all 17 locations sampled, asparagine was generally lower in Freeman compared with Goodstreak and Camelot. Asparagine concentration was positively correlated with kernel size and weight (r=0.37; p=0.03). In conclusion, the major differences in asparagine concentration were due to growing environment, although the cultivar Freeman may be a low asparagine accumulating genotype. In the second project, steaming of wheat kernels prior to milling was assessed to determine the effects on storage stability of whole wheat flour and on microbial load of wheat flour. Lipase, lipoxygenase, polyphenol oxidase, and peroxidase activities were decreased by up to 81%, 63%, 22%, and 34%, respectively, as the time of steaming increased up to 90 s. Steaming had no effect on starch and gluten properties. Steaming for 90 s reduced the total plate count in wheat by log 7 CFU/g. Upon storage free fatty acids decreased with respect to time of steaming. Time of steaming did not affect lipid oxidation in flour; however, total carbonyls produced in dough made from stored flour were decreased with the increase in steaming duration. Thus, steaming wheat kernels prior to milling reduced lipase activity and consequently hydrolytic rancidity during storage without affecting starch and gluten fractions. This treatment also dramatically reduced the microbial load in flour. Steam treatment did not affect oxidative rancidity in flour during storage, but did reduce oxidation once the flour was made into a dough.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Sabill�n L, Bianchini A, Stratton J, Rose DJ. 2017. Effect of saline organic acid solutions applied during wheat tempering on flour functionality. Cereal Chemistry 94:502-507.
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Poudel R, Bhatta M, Regassa T, Rose DJ. 2017. Influence of foliar fungicide treatment on lipolytic enzyme activity of whole wheat. Cereal Chemistry 94:633-639
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Progress 10/01/15 to 09/30/16
Outputs
Target Audience:Food manufacturers, food product developers, plant breeders Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Two graduate students received research training as a result of this project. How have the results been disseminated to communities of interest?Results have been disseminated in peer-reviewed publications and in scientific meetings. They have also been shared in workshops, meetings with food companies, and in individual discussions. What do you plan to do during the next reporting period to accomplish the goals?Continue our work on evaluating interventions to improve microbiological and chemical safety of wheat products.
Impacts
What was accomplished under these goals?
Cereals are important staple foods in the American diet. As staple foods, it is important that these foods be free of both microbial and chemical hazards. Examples of microbial hazards can include toxin-producing E. coli and Salmonella species. These microbes do not grow in dry grain or flour, but can stay dormant in the flour for many months. If the flour is then consumed without heat treatment contaminated flour can cause illness. The increased incidence of foodborne disease outbreaks caused by products containing flour has highlighted the fact that the food industry cannot rely on heat treatments applied by the consumers to ensure safety of flour-based products; therefore, strategies to reduce the microbial load of flour are needed. Cereal products can also be sources of chemical hazards, including mycotoxins, acrylamide, and heavy metals. Strategies to reduce the accumulation of these toxic substances through plant breeding or food processing are needed. The broad objectives of the NC-213 Multistate Project are to: 1) characterize quality and safety attributes of cereals, oilseeds, and their processed products, and to develop related measurement systems; 2) develop efficient operating and management systems that maintain quality, capture value, and preserve food safety in the farm-to-user supply chain; and 3) be a multi-institutional framework for the creation of measurable impacts generated by improvements in the supply chain that maintain quality, increase value, and protect food safety/security. Our group's contribution to this project was on objective 1. No contributions to objectives 2 and 3 were made during the reporting year. Specifically, we focused on pre-milling interventions to reduce the microbial load of wheat. In the first project, we continued our efforts to improve the safety of wheat grain prior to milling by further testing the saline-organic acid solutions as antimicrobial treatments. The tempering process of soft wheat was evaluated. At first tempering solutions were tested against enteric pathogens including Salmonella, E. coli O157:H7, and non-O157 shiga toxin-producing E. coli (STEC). In these experiments soft red winter wheat was inoculated with cocktails of either five serotypes of S. enterica, five kanamycin-resistant strains of E. coli O157:H7, or six serotypes of non-O157 STEC to achieve a 6.0 log CFU/g, followed by a resting time of 7 days to allow for microbial adaptation and moisture equilibration. During the resting period, inoculated samples were placed at temperatures of 2?C, 11?C, 24?C and 33?C to mimic the winter, spring/fall, and summer temperatures, respectively, encountered by wheat in storage. Besides water, solutions containing a combination of organic acid (acetic or lactic; 2.5% and 5.0% v/v) and NaCl (26% w/v) were used for tempering the wheat samples to 15.0% moisture. Grain samples were analyzed before and after tempering to determine the microbial reduction achieved by the tempering treatments at different seasonal temperatures. Regardless of temperature, the initial load of pathogens was reduced significantly by all treatments when compared to the control which was tempered with water (p<0.05). The best results for S. enterica were achieved using lactic acid 5%+NaCl 26% solution at 2?C, which resulted in 2.1 log CFU/g reduction. Implementation of organic acids and salt in tempering water prior to milling could benefit the milling industry and consumers by preventing or reducing the risk of pathogen contamination in milled products. Further experiments will be conducted using hard red winter wheat. Besides pathogenic microorganisms, the efficacy of adding organic acids and NaCl to tempering water to reduce natural microbial flora in soft wheat prior to milling and the impact on the microbiological quality and functional properties of the resulting flour were evaluated. Soft red winter wheat was tempered to 15.0% moisture by adding sterile distilled water (control) or tempering solutions containing acid (acetic or lactic; 2.5% and 5.0% v/v) and NaCl (26% w/v) and holding for 18 h at 23-24°C and 60% relative humidity. Wheat was analyzed before and after tempering for Total Plate Counts (TPC), yeasts, molds, coliform, and Enterobacteriaceae (Eb). The microbial load of the tempered wheat was significantly reduced by all organic acid-NaCl treatments (p<0.05). The combination of lactic acid (5%) and NaCl was the most effective against TPC and Eb (p<0.05), with an average reduction of 3.1 and 4.5 log CFU/g, respectively. After milling on a Quadrumat Jr, milled fractions were collected and sieved to separate the bran and germ from flour. Flour was evaluated by the same microbial analysis described for wheat. Additionally, flour functionality was evaluated by Rapid Visco Analyzer and Solvent Retention Capacity (SRC). The microbial load of the flour obtained from wheat tempered with lactic acid (5%)-NaCl was significantly lower (p<0.05) than the control flour and no significant differences in pasting properties among resulting flours were observed (p>0.05). In addition, there were no significant differences (p>0.05) in the SRC values among flours for the sodium carbonate solvent, which indicates that starch granules were not damaged by the tempering solutions. Addition of organic acids and NaCl in tempering water provides milled products with improved microbiological quality, with a minimal impact on functionality. This project may impact grain processors by affording them a strategy to produce soft wheat flour with higher microbial safety. In the second project, a microbial survey was conducted in a pilot scale flour milling facility to determine microbial loads and microbial distribution across the milling equipment. Indicator microorganisms of fecal contamination such as coliforms and Enterobacteriacea, as well as Salmonella spp. are among the microorganisms included in the survey. One hundred and seven sampling points were distributed among all processing areas including wheat receiving/cleaning, wheat milling, and finished product handling. A preliminary review of the data shows that pathogens are distributed at very low levels and microorganisms tend to concentrate in the equipment used to sort and clean wheat kernels prior to milling, on the break rolls, and on the screw conveyors that carry the final milled products. Further data analysis is still being carried out including a quantitative microbial risk assessment (QMRA) to evaluate the impact of the milling process on the ultimate safety of milling end products. The QMRA model will simulate the steps followed by grain after harvesting, from entering the milling system to the end product (i.e. flour or flour-based products). The model will be developed to evaluate the public health risks associated with the consumption of wheat-based products contaminated with E. coli O157:H7, Salmonella, and non-O157 STEC in the United States. The findings of this project will lead to better decision-making regarding strategies that could be applied throughout the wheat milling process to reduce microbial contamination and safeguard consumers.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Sabill�n, L, Stratton J, Rose DJ, Flores RA, Bianchini A. 2016. Reduction in microbial load of wheat by tempering with organic acid and saline solutions. Cereal Chemistry 93:638-646.
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Progress 10/10/14 to 09/30/15
Outputs
Target Audience:Food manufacturers, food product developers, plant breeders Changes/Problems:In addition to Improving the microbial safety of wheat flour through non-thermal pre-milling interventions, we will also assess the genotypic and environmental variation in lipase activity and asparagine in hard winter wheat produced in Nebraska. What opportunities for training and professional development has the project provided?Three graduate students received research training as a result of this project. How have the results been disseminated to communities of interest?Results have been disseminated in peer-reviewed publications and in scientific meetings. They have also been shared in workshops, meetings with food companies, and in individual discussions. What do you plan to do during the next reporting period to accomplish the goals?Determine functional and sensorial properties of products made from wholegrain and straight-grade flours that were conditioned with combinations of organic acids and salt prior to milling Determine the genotypic and environmental variation in lipase activity and asparagine in hard winter wheat produced in Nebraska.
Impacts
What was accomplished under these goals?
Cereals are important staple foods in the American diet. As staple foods, it is important that these foods be free of both microbial and chemical hazards. Examples of microbial hazards can include toxin-producing E. coli and Salmonella species. These microbes do not grow in dry grain or flour, but can stay dormant in the flour for many months. If the flour is then consumed without heat treatment contaminated flour can cause illness. The increased incidence of foodborne disease outbreaks caused by products containing flour has highlighted the fact that the food industry cannot rely on heat treatments applied by the consumers to ensure safety of flour-based products; therefore, strategies to reduce the microbial load of flour are needed. Cereal products can also be sources of chemical hazards, including mycotoxins, acrylamide, and heavy metals. Strategies to reduce the accumulation of these toxic substances through plant breeding or food processing are needed. The broad objectives of the NC-213 Multistate Project are to: 1) characterize quality and safety attributes of cereals, oilseeds, and their processed products, and to develop related measurement systems; 2) develop efficient operating and management systems that maintain quality, capture value, and preserve food safety in the farm-to-user supply chain; and 3) be a multi-institutional framework for the creation of measurable impacts generated by improvements in the supply chain that maintain quality, increase value, and protect food safety/security. Our group's contribution to this project was on objective 1. No contributions to objectives 2 and 3 were made during the reporting year. Specifically, we focused on pre-milling interventions to reduce the microbial load of wheat. First a survey was performed to determine the microbial contamination of wheats produced in Nebraska. Then, saline and acid solutions were used to temper wheat to determine the reduction in microbial load of the resulting wheat. In the first project, the effects of weather variables following wheat flowering on the microbiological quality of wheat were evaluated over two consecutive seasons. Three hard red winter wheat lines, three cultivars were planted in three contrasting regions. The natural microbial flora and deoxynivalenol (DON) concentration were analyzed. In the first season, aerobic plate count (APC), Enterobacteriaceae (Eb), yeasts and molds, and internal mold infection (IMI) were significantly lower in grain samples collected from Panhandle as compared to grain harvested from the South Central and Southeastern districts. No significant differences in the yeast counts were found in grain collected from all districts in the second year, but levels of IMI and mold counts were significantly higher in the Southeastern district as compared to the Panhandle district. DON was detected in all districts, but was below the advisory level of 1 mg/kg for processed wheat. In general, microbial load in wheat grain tended to be lower in those areas with lower relative humidity (below 65%) and with temperatures of less than 13.7°C and greater than 31.5°C. These results were published in a peer-reviewed journal. The results from this project may impact grain buyers and processors. For these individuals relative humidity and temperature following wheat flowering should be used as an additional parameter when selecting grain for higher microbiological safety. In the second project, the efficacy of adding organic acids and NaCl to tempering water to reduce microbial contamination in hard wheat was evaluated. Hard red winter wheat was tempered to 15.5% moisture by adding sterile distilled water (control) or tempering solutions containing organic acids (acetic, citric, lactic, or propionic; 1.0%, 2.5% or 5.0% v/v), NaCl (26%, or 52% w/v) or a combination of organic acid (acetic or lactic; 2.5% and 5.0% v/v) and NaCl (26%, or 52% w/v) and holding for 24 h at 23-24°C and 60% relative humidity. After tempering, the initial microbial load was significantly reduced by all the acid and NaCl treatments when compared to the control. Wheat tempered with 5% acetic, propionic, and lactic acids resulted in reductions of 1.7, 2.3 and 3.8 log CFU/g in aerobic plate count (APC), Enterobacteriaceae (Eb) and mold counts, respectively. The combined lactic acid and NaCl effects on reducing APC and Eb counts were greater than any single or paired combination effect, which suggests a synergistic interaction. The combination lactic acid (5.0%) and NaCl (52%) was the most effective against APC and Eb, with an average reduction of 4.3 and 4.7 log CFU/g, respectively. This project may impact grain processors by affording them a strategy to produce flour with higher microbial safety. The milling process of hard wheat tempered with organic acids and saline solutions may provide milled products with improved microbiological quality when compared with the traditional tempering process using water.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Sabillon L, Bianchini A, Stratton J, Rose D, Regassa T, Flores R. 2015. Microbial load of hard winter wheat varieties produced at three growing environments across the state of Nebraska, USA. AACC International Annual Meeting, Minneapolis, MN.
- Type:
Journal Articles
Status:
Accepted
Year Published:
2016
Citation:
Sabill�n, L, Stratton J, Rose DJ, Regassa TH, Bianchini A. 2016. Microbial load of hard red winter wheat produced at three growing environments across Nebraska, USA. Journal of Food Protection in press.
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