Progress 10/01/19 to 09/30/20
Outputs
Target Audience:Grain farmers, agricultural extension agents, scientists and quality control managers in food and feed industry, researchers in cereal sciences and food science and food safety officials. Changes/Problems: Major problems or delays: Due to COVID-19 pandemic, the labs were lockdown from March 15 to June 22. The lab in the Center of Excellence for Post-Harvest Technology was not reopen until July 6, 2020. During this period, only limited research was conducted. After reopening, the research activity was slower than planned in the proposal because of the social distance issue. Due to the pandemic and social distance issues in the lab, there was no undergraduate students to participate in the project activity. Significant deviations from research schedule or goals: Since March 15,2020, graduate students were required to work on thesis writing due to lab lockdown and limited access to the lab. Both graduate students completed their literature review parts of the thesis. In addition, we conducted the research activities based on what we could do under current condition/situation, not according to the approved Timeline in the proposal. The chemical compositions of essential oils used in the research were obtained from literatures, not by GC analysis because the collaborator who is responsible for chemical composition analysis retired right after the project started, and the new personnel in charge of the analytical lab does not know how to operate GC. What opportunities for training and professional development has the project provided?Three graduate students have been involved in the project. Sawo Eesiah has been trained to test the anti-insect potential of essential oils (EOs) as her thesis research. She has been trained to test the anti-insect activity of 5 EOs and she will select two most effective EOs to test their synergy. Ivana Ramos Pedroso was trained to conduct anti-fungal activity of essential oils which will be her thesis research. She has been trained with experimental design, mycotoxin extraction, and purification. Both of them are under training to write thesis and make presentations. Rabiatu Bonku was a continued graduate student. She was supported by this project for 2 semesters and involved in this project by helping Sawo Eesiah in terms of data collection, calculation and graphing. How have the results been disseminated to communities of interest?The results of anti-insect activity of different essential oils were virtually disseminated at CAES student showcase. Due to COVID-19 pandemic, other events for dissemination such as 2020 Small Farms Week and 2020 Small Farm Field Day were canceled. We submitted abstracts to The Southwest & Southeastern Regional Meeting of the American Chemical Society scheduled on October 15-16, 2020 in New Orleans. However, the meeting was canceled about one week before the scheduled meeting date due to the pandemic. We recently submitted three abstracts to IFT 2021 Annual Meeting and Food Expo. We also plan to disseminate the research findings in 2021 Small Farms Week and 2021 Small Farm Field Day, and other conferences either virtually or in person if possible. What do you plan to do during the next reporting period to accomplish the goals?During the next reporting period, the team plans to complete the rest part of objective 2 (study the impacts of single EOs, PSE and GSE on insect mortality and oviposition in the corn grains), objective 3 (evaluate the effect of single EO, GSE and PSE on mold growth and mycotoxin production) and part of the objective 4 (study the synergies among EOs, between EO and GSE/PSE against storage insects, molds and mycotoxins). However, we may be unable to test and anti-insect and antifungal activities of GSE (grape seed extract) and PSE (peanut skin extract) due to the problems/issues below.
Impacts
What was accomplished under these goals?
1. Major activities completed; For objective 1: We have purchased five different EOs, prepared GSE and PSE to be used for the project, but their composition analyses have not been done due to the personnel change of college's analytical service lab and COVID-19 pandemic. The five EOs are cinnamon oil, clove oil, orange terpenes, oregano oil and thyme oil. They are approved by FDA as General Recognized as Safety (GRAS). We have done literature review to obtain the chemical composition data of each EO and they will be used to interpret the results obtained from other objectives of this project. For objective 2: The team has done anti-insect experiments of five EOs at concentrations 1%, 5% and 10% in organic corn grains using a simulated fumigation method. The mortality of corn weevils during storage at each EO concentration was calculated. The experiment at each EO concentration was repeated 3 times. For objective 3: The team has worked together and got USDA's Approval to purchase pathogenic mold cultures for the research (it took about 6 months to get the approval). We purchased all mold cultures, equipment and supplies needed to conduct the research activities. The methods for extraction and purification of aflatoxins and ochratoxin A were optimized. We are in the stage to determine mold growth and mycotoxin production in organic corn grains under different storage conditions (moisture-temperature combinations). 2. Specific objectives met; Achievement of Objective 1: Through literature review, the chemical composition of the five essentials were identified. The major chemical constituents of cinnamon bark oil are cinnamaldehyde (65-80%) and eugenol (5-10%). The main constituents of the clove essential oil are eugenol (55.60-74.64 %), eugenyl acetate (8.7-20.54 %), caryophyllene (12.79-14.84 %), and α-humulene (1.53-2.75 %) varied with source plant. Orange essential oil is produced from rind of an orange fruit and it is composed of mostly d-limonene (91-97%) followed by β-myrcene (1.9-4.3%) and β-pinene (0.2-1%). The major components of oregano essential oil were carvacrol (70.2 -92.5%), c-terpinene (1.0-5.6%), and thymol (2.2-2.5%). The chemical composition (the percentage of each compound) of essential oils determines if they attract, repel or kill corn weevils. Achievement of Objective 2: The anti-insect activity tests show the mortality of corn weevils increased with the concentrations of essential oils (EOs), and cinnamon oil and clove oil showed highest anti-insect activity among all tested EOs. Most of EOs at concentration 1% did not affect the maize weevil in the organic corn grains. Fumigation with 5% EO significantly increased mortality of maize weevils and the highest mortality was observed in the corn grains fumigated with clove oil (40%) and cinnamon oil (37%). At 10% EO concentration, cinnamon oil had caused highest mortality to corn weevils followed by clove oil. At week 4, the mortality of weevils in the corn grains treated 10% cinnamon oil and clove oil were 83% and 80% respectively, but no significant increase in weevil mortality was observed from week 4 to week 5. For all treatments (including control), the mortality of maize weevil increased with storage time. Achievement of Objective 3: We found that 80% methanol in water at solvent to sample ratio 4:1 gave the highest aflatoxin recovery. Florisil column was the best for aflatoxin purification, Osis-HLB column was good for OTA purification, but Puri Tox column did not give good purification result. Under the optimized the extraction and purification condition, the recoveries of aflatoxin B1, B2, G1 and G2 were 96.01%, 89.04%, 85.09% and 85.01%. It was found that at lower moisture level (9.9%) the organic corn grains were not molded when they were stored at 35 °C for 5 weeks, but at higher moisture (14.6-16.9%) the molds were visible within one week at all storage temperatures (25, 30 and 35°C), and aflatoxin B1, B2, G1 and G2 were detected correspondingly in the molded corn grains. 3. Significant results achieved, including major findings, developments, or conclusions (both positive and negative); Cinnamon oil and clove oil showed significant anti-insect activity against maize weevil at concentration 5% and higher. Moisture of corn grains was the most detrimental factor for the deterioration of stored organic corn grains in terms of mold growth and aflatoxin production. The extraction and purification procedures are extremely important for accurate quantification of mycotoxins in cereal grains, and have to be optimized for each type of grain. 4. Key outcomes or other accomplishments realized; The results obtained so far indicate that cinnamon oil and clove oil have great potential to replace toxic pesticide such as Centynal™ EC Insecticide for corn grain preservation. Because these two essential oils are GRAS (Generally Recognized as Safe), their use should be environmentally friendly and safer to the agricultural workers. The project outcomes obtained during this reporting period will not only contribute to the knowledge about insecticidal activity of essential oils, but also contribute to food security, food safety and human health.
Publications
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