Location: Food Quality Laboratory
2023 Annual Report
Objectives
Objective 1. Enhance key organoleptic and nutritional qualities of major horticultural crops using emerging production and post-harvest handling practices.
Sub-obj. 1A. Improve food quality and nutrition, and harvesting efficiency for vegetables grown via controlled environment agriculture (CEA).
Sub-obj. 1B. Develop novel technologies to support NASA’s mission in growing microgreens in space.
Objective 2. Reduce post-harvest loss and waste and enhance marketability of
fresh produce.
Sub-obj. 2A. Non-destructive monitoring of produce quality and maturity via a paper sensor.
Sub-obj. 2B. Improve quality and shelf life of fresh produce through collaborative breeding and cultivar selection.
Sub-obj. 2C: Predicting consumers’ preferences for fruits and vegetables through advanced analyses of digital imagery and emotions.
Objective 3. Improve product quality and sustainability through novel fresh-cut processing technologies and process optimization.
Sub-obj. 3A. Develop novel fresh-cut produce wash and disinfection technologies for comprehensive improvement in food quality and safety.
Sub-obj. 3B. Determine chemical profile of fresh-cut produce wash water in support of cost-effective water treatment and reuse.
Sub-obj. 3C. Assess the potential use of nanoparticle coatings on the contact surface of equipment to optimize fresh-cut processing.
Approach
This project takes an integrated and holistic approach to tackle major food security problems by supporting efficient growth and harvesting of nutrient-dense food products and reducing post-harvest food loss and waste. This project consists three objectives. In objective 1, we will investigate the effect of light wavelength, intensity, and photoperiod on the growth, sensorial quality, and phytonutrient content of specialty vegetables. We will develop mechanical devices to facilitate harvesting of microgreens while minimizing tissue damage. We will also develop and/or evaluate soil mixes and soil-less growth media for seed fixation in microgravity. In objective 2, our team of scientists will collaborate with ARS breeders to identify lettuce cultivars resistant to enzymatic browning and having improved post-harvest quality and shelf life. We will continue collaborating with our university partner (and co-inventor) to advance our patent-pending paper sensor array for nondestructive quality evaluation. In objective 3, we will work with our industry partners to further develop, optimize, and commercialize our patented produce washing and disinfection technology. We will develop and optimize a novel in-flight washing system to improve the food quality and safety of fresh-cut products. This will be a continuation and expansion of the patented in-flight washing technology developed under a previous project. We will also investigate the major chemical components of fresh-cut produce wash water and develop approaches to support safe and cost-effective water reuse. Specifically, we will identify major compounds present in produce; their release during cutting; their reactivity with free chlorine during different washing stages; how such reaction contributes to the loss of free chlorine in wash water, and to difficulties in maintaining adequate chlorine levels; the type and amount of harmful disinfectant byproducts thus produced during washing; and effective methods to remove or mitigate the chemical oxygen demand (COD) and chlorine demand (CLD) in wash water during fresh-cut processing.
Progress Report
Progress was made on all 3 objectives and their subobjectives, all of which fall under NP306, Produce Quality and New Uses. Progress on this project centers on enhancing key organoleptic and nutritional qualities of major horticultural crops using innovative controlled environment agricultural production, novel post-harvest handling technologies and process optimization, reducing post-harvest losses and enhancing marketability of fresh produce.
In Objective 1, we initiated the design and development of a harvesting device for microgreens and tested its functionality for harvesting microgreens. We found that the diameter and strength of thin wire are critical factors for harvesting efficiency. Follow up studies will focus on material selection and configurations to achieve desired harvested crop quality. We also conceptualized and developed (in collaboration with University of Massachusetts) seed spacing and irrigation system (SSIS) to support seed delivery, germination, and programmable hydration under simulated microgravity. We shared information on this design to NASA who expressed interest in its potential use for irrigation in space. In addition, we also designed and prototyped a flexible hydroponics system which allows for control of plant spacing and root zone depth. The system also includes a top surface which physically separates plant shoots and leaves from the nutrient solution/root zone, improving usefulness for microbial inoculation studies and reducing the incidence of algae growth in the system. Because this system houses plants in individual net cups, plants are significantly easier to handle, move between systems, and harvest than in comparable setups. This system could further enable the automated harvesting of CEA leafy greens without touching the growth media, leading to improvement in food safety and quality of harvested leafy greens.
In Objective 2, we tested a novel chromogenic sensor array for detecting plant pathogens affecting produce and floral plants. Among the 21 dyes tested, 9 responded to the volatile organic compounds (VOCs) from Ralstonia. These results will facilitate further development and optimization of the sensor array as a non-destructive surveillance and early detection tool for plant pathogens. We broadened the research scope for the identification of browning resistant romaine lettuce cultivars and further investigated (in collaboration with a geneticist) the genome-wide association study (GWAS) of browning discoloration in cut lettuce. We also conducted product quality evaluation using both in person and on-line images. In our analysis of digital images we concluded that total time from harvest is critical for shelf life of fresh cut lettuce, regardless of when the processing occurs after harvest. We studied the effects of fixation and gaze-based metrics using iMotion and Tobii Pro Fusion eye tracker software in identifying areas of interest in the evaluation of sensory traits and determination of liking and intent to purchase fresh produce.
In Objective 3, we developed and tested the second prototype of our in-flight washer (IFW) for organic matter removal and bacterial inactivation. We collaborated with a large fresh-cut produce company to further evaluate the performance of this second IFW prototype. Our industry collaborators considered this innovation a “game changer” for fresh-cut produce wash system and operation. We also systematically characterized chlorine disinfection byproducts via laboratory, pilot plant, and commercial trials.
We worked with a collaborator (Binghamton University) to develop and test the application of an AI-enhanced E-nose for volatile compounds. We also collaborated with University of Florida to characterize the specific gravity, refractive index, and viscosity of 25 vegetable oils (sunflower, chia, walnut, virgin coconut, etc). We reported that sunflower oil is the most effective medium for stimulating saliva production without increasing the mortality of the targeted insects. These results enabled the collection of large amounts of saliva samples, advancing the understanding of the mechanisms of plant diseases induced by those pests.
Accomplishments
1. Smart use of far-red light to produce nutritious edible mustard flowers. Far red (FR) light has traditionally been considered as not photosynthetically useful. Although its value in increasing plant stem elongation as a part of shade response is gradually being recognized, its overall effect on plant growth, flowering, and phytonutrient synthesis remains largely unknown. ARS researchers at Beltsville, Maryland, comprehensively investigated the effects of FR on the vegetative and reproductive growth and phytonutrient composition of Ruby Streaks mustard. They reported, for the first time, that FR alone and in combination with other light spectra remarkably accelerated flower emergence and development. They also reported the exceptionally high glucosinolate content in Ruby Streaks flowers for the first time which, together with the accelerated flower production, opens the opportunity of utilizing flowers from this crop as a nutritious edible product.
2. Pioneering research on nutrition and microbial profiles of CEA leafy greens. Controlled environment agriculture (CEA) is the fastest growing specialty crop sector and has the potential to greatly enhance the specialty crop industry’s climate resilience, water and land use efficiency, and year-round production. However, as a new production system, CEA has unique challenges and opportunities, with critical data gaps and unmet research needs hindering further growth and profitability. ARS researchers at Beltsville, Maryland, pioneered research that comparatively evaluated the phytochemical profiles and microbiome composition of baby spinach grown using CEA and open field production (OFP) methods. They tested a diversity of CEA and OFP samples from local retail stores and conducted focused studies on baby spinach from two large CEA and OFP brands. While they found similar nutrient profiles for baby spinach from CEA and OFP, they reported for the first time a vastly different microbiome composition, in which Pseudomonas and Pantoea are the predominate genera in OFP while a Cyanobacteria genus Synechocystis was identified as the most abundant bacteria on CEA baby spinach. Since Synechocystis is commonly associated with algae growth, our findings underscore the importance of algae control during CEA production. Findings on nutrition profile also provide important information for health-conscious consumers to make informed purchasing decision, and for industry to formulate evidence-based marketing and process improvement strategies, as well as new products.
3. Can you use a half of a peanut kernel as a seed and the other half as food. Peanuts are America’s favorite food and peanut farmer’s key income source. Yet, ~182 million pounds per year of edible peanuts are used as seeds. As peanut embryos (7-8% of total kernel mass) contain all the genetic material for propagation, peanut kernels could potentially be split into embryos (EM) or embryo plus partial cotyledons (EPC) for use as “seeds”, and the remaining cotyledons recovered as food. While this “out of the box” idea has been embraced by the industry, systematic evaluation of its feasibility is lacking. ARS researchers at the Food Quality Lab in Beltsville, Maryland, were sought out by peanut experts for technical support. Pioneering research showed that peanut kernels can be split to recover a portion of the cotyledon tissue as food, leaving the remaining embryo-containing partial kernel as seed. Study results are being used by engineers at the University of Maryland to develop a machine vision-guided cutting and sorting device to enable peanut kernel splitting at the commercial scale. Project success could lead to recovery of up to 174 million pounds (~$124 million) of the nutrient-rich cotyledons for edible markets without compromising seed germination and plant growth, a win-win for sustainable peanut production, and food and nutrition security.
4. Pioneering research on the application of emotion sensors for the online food environment. Online grocery shopping spiked during the COVID-19 pandemic, and while it has declined from 2021, the current sales are still over 100% greater than pre-pandemic years. Fresh (perishable) foods are currently accounting for nearly 40% of all online food sales. E-commerce can potentially influence consumption of fresh produce in the USA, especially among younger consumers and selected population groups that are inclined to use e-shopping. ARS researchers at Beltsville, Maryland, utilized emotion sensors, in particular an eye tracking device, to investigate areas of interest (AOI) of the online food environment such as image quality, descriptive information, and stickers/labeling. The research addresses how the AOI individually or in combination influence consumer behavior and potential decisions. The results with four apple cultivars demonstrated that knowledge of AOI can be instrumental in developing effective online food environments that aid consumers in making decisions about fresh produce purchases.
5. A digital app to help consumers navigate and select their ideal apples. There are over 7,500 apple varieties grown worldwide, each with its own set of characteristics such as flavor, texture, and appearance. In the United States, 11.1 billion pounds of apples of more than 100 different varieties were produced in 2021 with a farm gate value of $3.2 billion. The sheer variety of apples available provides a good opportunity for a digital app that can help consumers navigate and select the ideal options based on their preferences. ARS researchers at Beltsville, Maryland, in collaboration with the U.S. Apple Association are developing an app that would provide information on sensory traits and nutritional content of available apple varieties, including sweetness, sourness, juiciness, crispness, flavor, color, texture, and selected nutrient content. Physicochemical data has been continually collected, and studies on apple qualities valued by consumers are ongoing, both in person and online. The final goal is to build a robust database that can help guide and determine consumer preferences, serving as a reference for markets and for future research studies.
Review Publications
Teng, Z., Luo, Y., Pearlstein, D.J., Zhou, B., Johnson, C.M., Wang, Q., Fonseca, J.M. 2022. Agarose hydrogel composite supports microgreen growth with continuous water supply under terrestrial and microgravitational conditions. International Journal of Biological Macromolecules. 220:135-146. https://doi.org/10.1016/j.ijbiomac.2022.08.046.
Zhang, T., Luo, Y., Zhou, B., Teng, Z., Huang, C., Nou, X. 2022. Sequential application of peracetic acid and UV irradiation (PAAUV/PAA) for improved bacterial inactivation in fresh-cut produce wash water. ACS Environmental Science & Technology Water. 2(7):1247-1253. https://doi.org/10.1021/acsestwater.2c00087.
Teng, Z., Luo, Y., Pearlstein, D.J., Wheeler, R., Johnson, C., Wang, Q., Fonseca, J.M. 2022. Microgreens for home, commercial, and space farming – a comprehensive update of the most recent developments. Annual Review of Food Science & Technology. 14:539-562. https://doi.org/10.1146/annurev-food-060721-024636.
Liu, Z., Teng, Z., Pearlstein, D.J., Chen, P., Yu, L., Zhou, B., Luo, Y., Sun, J. 2022. Effects of different light-emitting diode illumination on bioactive compounds in mustard “Ruby Streak” microgreens by ultra-high performance liquid chromatography high-resolution mass spectrometry. ACS Food Science and Technology. 2(9):1483–1494. https://doi.org/10.1021/acsfoodscitech.2c00193.
Luo, X., Plunkert, M., Teng, Z., Mackenzie, K., Guo, L., Luo, Y., Hytönen, T., Liu, Z. 2023. Two MYB activators of anthocyanin biosynthesis exhibit specialized activity in petiole and fruit of diploid strawberry. New Phytologist. 74(5):1517-1531. https://doi.org/10.1093/jxb/erac507.
Zhou, B., Luo, Y., Huang, L., Fonseca, J.M., Yan, H., Huang, J. 2022. Determining effects of temperature abuse timing on shelf life of RTE baby spinach through microbial growth models and its correlation with sensory quality. Postharvest Biology and Technology. 133. Article 108639. https://doi.org/10.1016/j.foodcont.2021.108639.
Zhou, B., Luo, Y., Nou, X., Mwangi, E., Poverenov, E., Demokritou, P., Fonseca, J.M. 2023. Effects of a novel combination of gallic acid, hydrogen peroxide and lactic acid on pathogen inactivation and shelf-life of baby spinach. Food Control. 143. Article 109284. https://doi.org/10.1016/j.foodcont.2022.109284.
