Graduation Year

2019

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Biology (Cell Biology, Microbiology, Molecular Biology)

Major Professor

Maria Cecilia do Nascimento Nunes, Ph.D.

Committee Member

Sandy Westerheide, Ph.D.

Committee Member

Brant Burkhardt, Ph.D.

Keywords

abiotic stress, ascorbic acid, carotenoids, proteomics, supply chain, tomato

Abstract

Fresh fruits and vegetables (FFVs) are the most frequently wasted foods because of their perishability and handling requirements. However, there is a lack of information on how much each step of the supply chain impacts FFVs quality, particularly on tomatoes, and what measures need to be taken for an immediate and effective impact on waste reduction. There is also no information on how the supply chain affects the proteome of the tomato and what proteins are differentially regulated by the most impactful steps of the supply chain. The objectives of the work presented on this thesis were to evaluate the decline in the overall quality and quantify tomato waste at each step of the supply chain, from the farm to consumer; and to determine what proteins are impacted by the decline in quality that is associated with temperature abuse. To determine overall quality and tomato waste, light-red tomatoes were exposed to an optimum temperature (13 °C) and eighteen different time-temperature scenarios, normally encountered during supply chain, and sensory and physicochemical attributes measured at each step. To determine the impact of chilling and non-chilling temperatures normally encountered during tomato supply chain, on the proteome, light-red tomatoes were exposed to an optimum temperature (13 °C) and to two time and temperature supply chain scenarios (2 °C and 25 °C) that showed the most negative impact on tomato overall quality, and physicochemical and proteomic attributes were measured at each step. For the first tomato harvest, the steps with the highest impact on quality and waste were shipping to distribution center (DC; 20°C), cooling at the grower (25°C) and storing at the consumer (4°C). For the second tomato harvest, shipping to the store (2°C), cooling at the farm (10°C) and displaying at the store (20°C) negatively impacted quality. High temperatures during cooling, shipping and

store display impacted sensory quality and resulted in increased weight loss, and decreased sugar, carotenoids, and ascorbic acid contents. Although low temperatures during shipping, cooling and consumer did not impact tomato sensory quality, they contributed to a decline in sugar, carotenoids and ascorbic acid contents. Overall, the most impactful steps on tomato quality and waste, regardless of the temperature, were shipping to DC, cooling, shipping to stores, displaying at the store, and consumer storage. Analysis of the differentially expressed proteins in the tomato showed that metabolic proteins were greatly impacted by temperature abuses such as phosphomannomutase, heme oxygenase 1, and MAP kinase; and that proteins regulating cellular membrane integrity such as vacuolar protein sorting-associated protein were also impacted.

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