ASSESSMENT OF GRAIN SAFETY IN DEVELOPING NATIONS by José Rodrigo Mendoza Jiménez A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy Major: Food Science & Technology Under the Supervision of Professors Andréia Bianchini and Jayne E. Stratton Lincoln, Nebraska December, 2020 ASSESSMENT OF GRAIN SAFETY IN DEVELOPING NATIONS José Rodrigo Mendoza Jiménez, Ph.D. University of Nebraska, 2020 Advisor: Andréia Bianchini Grains are the most widely consumed foods worldwide, with maize (Zea mays) being frequently consumed in developing countries where it feeds approximately 900 million people under the poverty line of 2 USD per day. While grain handling practices are acceptable in most developed nations, many developing nations still face challenges such as inadequate field management, drying, and storage. Faulty grain handling along with unavoidably humid climates result in recurrent fungal growth and spoilage, which compromises both the end-quality and safety of the harvest. This becomes particularly problematic where there is little awareness about health risks associated with poor quality grain. Fungi are contaminants of maize and some can produce toxins, known as mycotoxins, that both devalue crop marketability and have detrimental health effects, especially to those malnourished. As some households depend on their harvest for self- consumption, losses due to fungi endanger their food security. To abate the threat posed by mycotoxigenic fungi on maize among developing nations, this research was conducted as a compilation of works in several countries. More specifically, it describes agricultural practices currently in use in developing nations, provides an overview of mycotoxin prevalence and approaches that can be used to improve grain safety post-harvest through proper storage. Additionally, it provides a platform to evaluate the economic feasibility of storage technologies for maize storage at household level. While the countries of focus were Guatemala, Honduras and Nepal, findings presented can lead to improved decision- making within any maize production chain to safeguard consumers throughout the developing world. iii Acknowledgements I wish to show my gratitude to every professor, colleague, friend and family member for their support during my doctoral studies journey in the Food Science & Technology department at the University of Nebraska-Lincoln. To my advisers and graduate committee, I appreciate your invaluable guidance. “You cannot hope to build a better world without improving the individuals. To that end, each of us must work for our own improvement.” - Marie Skłodowska Curie iv Preface The present doctoral dissertation is organized in five chapters that provide an overview of mycotoxins in maize production chains, mycotoxin surveying, and potential benefits of interventions aiming to decrease fungal and mycotoxin contamination, from farm to fork. Chapter 1 - Mycotoxins in Cereal Grains. José Rodrigo Mendoza Jiménez1, Lakshmikantha Channaiah2, Andréia Bianchini1 1University of Nebraska–Lincoln. Food Science & Technology. Food Innovation Center. 1901 N 21st St. Lincoln, NE 68588. 2Microbiology. AIB International. PO Box 3999. 1213 Bakers Way. Manhattan, KS 66505-3999, USA Chapter 2 - Assessment of Handling Practices for Maize Growers and Marketers in Food-Insecure Regions of Western Honduras. José Rodrigo Mendoza1,2, Luis Sabillón3, Raúl Espinal5, John Leslie4, Andréia Bianchini1,2 1 Food Science & Technology. University of Nebraska-Lincoln, Lincoln, NE 68588. 2 The Food Processing Center. University of Nebraska-Lincoln, Lincoln, NE 68588. 3 Family and Consumer Sciences. New Mexico State University. Las Cruces, NM 88003. 4Plant Pathology. Kansas State University, Manhattan, KS. 5 Food Science & Technology. Zamorano University, P.O. Box 93, Honduras. Chapter 3 - Survey on the Occurrence of Aflatoxins in Maize from Western Nepal. José Rodrigo Mendoza1, Emily Robinson2, Ram Kumar Shrestha4, Gopal Bahadur K.C.4, John Leslie3, Jagger Harvey3, Andréia Bianchini1 1 Food Science & Technology. University of Nebraska-Lincoln, Lincoln, NE. 68588. 2 Statistics. University of Nebraska-Lincoln, Lincoln, NE. 68583. 3Plant Pathology. Kansas State University, Manhattan, KS. 4Plant Pathology. Institute of Agriculture and Animal Science, Nepal. Chapter 4 - Evaluating Maize Storage Technologies for the Control of Fungi and Mycotoxins in the Western Highlands of Guatemala. José Rodrigo Mendoza1, María G. Trejo3, Vivian S. Montoya3, Car Reen Kok1, Walfer Martinez4, Ana Silvia Colmenares2, Carlos Campabadal5, Andréia Bianchini1 1 Food Science and Technology. University of Nebraska-Lincoln, Lincoln, NE. 2 Food Engineering. Universidad del Valle de Guatemala. Guatemala City, Guatemala. 3 Biochemistry and Microbiology. Universidad del Valle de Guatemala. Guatemala City, Guatemala. 4 Agronomic Engineering. Centro Universitario de Noroccidente. Universidad de San Carlos de Guatemala. Huehuetenango, Guatemala. 5 Grain Science and Industry. Kansas State University, Manhattan, KS. Chapter 5 - Financial Feasibility Analysis of Maize Storage Alternatives for Smallholder Farm Households: A Case Study in Guatemala. José Rodrigo Mendoza1, Andréia Bianchini1, Fabio L. Mattos2 1 Department of Food Science & Technology, University of Nebraska. Lincoln, NE, USA 2 Department of Agricultural Economics, University of Nebraska. Lincoln, NE, USA v Table of Contents List of Tables………………………………………………………………………………vii List of Figures……………………………………………………………………………...ix Chapter 1 - Mycotoxins in Cereal Grains Abstract……………………………………………………………………………...1 Mycotoxins…………………………………………………………………………..1 Important mycotoxin-producing fungal species and mycotoxins associated with cereal grains……………………………………………………………………….…2 Factors that influence mold growth and mycotoxin production…..….........................9 Controlling mycotoxins in grains and grain-based products…………………...…..11 Mycotoxin sampling……………………………………………………………......40 Mycotoxin detection methods……………………………………………………...44 References…………………………………………………………………….........52 Chapter 2 - Assessment of Handling Practices for Maize Growers and Marketers in Food-Insecure Regions of Western Honduras Abstract………………………………………………………………………….....80 Introduction………………………………………………………………………...80 Materials and Methods……………………………………………………………..82 Results and Discussion……………………………………………………………..85 Conclusions………………………………………………………………………...99 Acknowledgements……………………………………………………………….100 References………………………………………………………………………...100 vi Chapter 3 - Survey on the Occurrence of Aflatoxins in Maize from Western Nepal Abstract…………………………………………………………………………...105 Introduction……………………………………………………………………….106 Materials and Methods……………………………………………………………109 Results and Discussion……………………………………………………………113 Conclusions……………………………………………………………………….121 Acknowledgements……………………………………………………………….121 References………………………………………………………………………...122 Chapter 4 - Evaluating Maize Storage Technologies for the Control of Fungi and Mycotoxins in the Western Highlands of Guatemala Abstract…………………………………………………………………………...128 Introduction……………………………………………………………………….129 Materials and Methods…………………………………………………………....131 Results and Discussion…………………………………………………………....134 Conclusions……………………………………………………………………….141 Acknowledgements……………………………………………………………….141 References………………………………………………………………………...142 Chapter 5 - Financial Feasibility Analysis of Maize Storage Alternatives for Smallholder Farm Households: A Case Study in Guatemala Abstract…………………………………………………………………………...147 Introduction……………………………………………………………………….148 Materials and Methods……………………………………………………………150 Results and Discussion……………………………………………………………159 Conclusions……………………………………………………………………….163 Acknowledgements……………………………………………………………….163 References………………………………………………………………………...164 Concluding Remarks…………………………………………………………………....169 Future Work…………………………………………………………………………......171 Appendix…………………………………………………………………………………172 vii List of Tables Chapter 1 - Mycotoxins in Cereal Grains Table 1. Selected mycotoxins associated with major cereal grains…………………..4 Table 2. Examples of sufficiency and toxicity of mineral elements in crop plants.....17 Table 3. Examples of thermal processing effects on mycotoxins...............................32 Table 4. Examples of methods used for mycotoxin detection…................................47 Chapter 2 - Assessment of Handling Practices for Maize Growers and Marketers in Food-Insecure Regions of Western Honduras Table 1. Location of surveyed maize growers and marketers in Western Honduras..84 Table 2. Timing of pest control by maize growers in regions of Western Honduras...92 Table 3. Marketed maize origin of selected regions within Western Honduras.......96 Table 4. Frequency of pest control for marketers in regions of Western Honduras....97 Table 5. Marketers’ maize fate in selected regions within Western Honduras...........99 Chapter 3 - Survey on the Occurrence of Aflatoxins in Maize from Western Nepal Table 1. Maize mycotoxin recovery assays via fluorometry…………………....…113 Table 2. Summarized aflatoxin contamination levels in maize collected from districts of Western Nepal, Round 1 (March - April, 2018)……………………………...…115 Table 3. Summarized aflatoxin contamination levels in maize collected from districts of Western Nepal, Round 2 (October - November, 2018)…………………………116 Table 4. Estimated probability of having aflatoxin contamination in maize from Western Nepal. Probabilities