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ARS Home » Pacific West Area » Hilo, Hawaii » Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center » Tropical Crop and Commodity Protection Research » People » Marisa Wall
Marisa Wall

Center Director

Contact Information

USDA-ARS 
Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center
64 Nowelo St.
Hilo, Hawaii 96720 
Ph: (808) 932-2113
Fax: (808) 959-5470

 

Marisa Wall

Publications

via ARIS System

Education

  • B.S. Horticulture, Pennsylvania State University, 1982
  • M.S., Horticulture, University of Maryland, 1986
  • Ph.D., Horticulture, University of Maryland, 1989

Academic Positions

Research Accomplishments

I have been leading research programs in the areas of postharvest physiology, vegetable breeding, and crop production for over 26 years. My areas of expertise include postharvest physiology of horticultural crops, biochemical quality analyses, and quarantine treatment of fresh commodities. Prior to joining ARS, I was Professor of Horticulture at New Mexico State University where I initiated the first programs in sweet onion breeding and postharvest physiology, with supporting teaching and extension activities. My current research is focused on postharvest physiology, quarantine treatment and export, and food technology for tropical crops, but my unique interdisciplinary experience enables me to lead research programs that encompass an entire production and postharvest system, from the seed to the consumer.


Quality of tropical crops following irradiation treatment
Irradiation can be used as a postharvest treatment to control quarantine insect pests for export of fresh fruit and vegetables to markets where they command premium prices. The economic viability of irradiation as a quarantine treatment improves if a diversity of crops can be treated. My research is focused on defining the radiotolerance limits for high-value, tropical crops, and mixtures of tropical fruit. I have determined the compositional, sensory and storage quality of these crops following quarantine irradiation treatment, and elucidated the preharvest and physiological conditions that impact radiotolerance. The research supports the USDA-APHIS regulations allowing for export of fresh commodities following quarantine irradiation treatment and has greatly expanded exports. Hawaii's specialty crop exporters confidently irradiate and market over 20 million pounds annually.

Tropical fruit entering irradiation facility             Dragon fruit following irradiation treatment

Macadamia nut biochemistry and processing quality
Three major quality defects of macadamia nuts are gray kernel disorder, internal browning after roasting, and off-flavor development (oxidation and rancidity) during storage. My research has defined the biochemical and physical factors that contribute to kernel browning and oxidation, and established the preharvest and processing conditions under which these disorders manifest. Our lab quantified the phytochemicals, tocotrienols and squalene, in several cultivars of macadamia nuts grown in three microclimates, and identified cultivars with superior oxidative stability, enabling longer term storage. We also proved that a bacteria (Enterobacter cloacae) causes gray kernel disorder and established the environmental conditions optimal for disease development. My research provided the first understanding of the impact of initial kernel composition on post-processing quality, and demonstrated the importance of well-controlled processing conditions on macadamia kernel quality. The results have been used by the macadamia industry to optimize harvest and processing steps to enhance quality.

Internal browning of macadamia nuts Grey kernel disorder

Tropical fruit nutritional composition
Following the decline of sugarcane, Hawaii's agricultural base shifted to diversified small farms producing exotic tropical crops. New specialty fruit orchards are being planted annually and market supply is expected to increase greatly as trees reach full production. My research established precise compositional analyses for cultivars of five tropical fruits (banana, papaya, lychee, longan, and rambutan) grown in different micro-climates and soil types. The analyses were the most specific and sensitive determination of vitamin and mineral concentrations to date for tropical fruit. The fruit composition data is used to market these exotic fruit and to evaluate diets for nutritional adequacy.

Banana bunches at harvestFresh PapayaFresh rambutans

Postharvest practices to improve tropical fruit quality
Postharvest practices to manage diseases, improve fruit quality, and extend the shelf-life of longans and rambutans were identified. The most suitable packaging systems were established for maintaining postharvest quality under optimum temperatures, as well as under fluctuating temperature regimes commonly experienced during the postharvest chain.In related research, we are investigating modified atmosphere packaging of fresh papaya for potential marine shipment to export markets.Adoption of a better packaging system for specialty fruit does not require a change in field practices, but can reduce postharvest quality problems which have been major constraints during export and marketing.

Honors, Awards, Achievements and Recognition: