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United States Department of Agriculture

Agricultural Research Service

Research Project: Metabolomic and Microbial Profiling of Tropical/subtropical Fruits and Small Fruits for Quality Factors and Microbial Stability

Location: Citrus and Other Subtropical Products Research

Project Number: 6034-41430-005-00
Project Type: Appropriated

Start Date: Jul 20, 2010
End Date: Jul 19, 2015

Objective:
1. Evaluate the effect of genetics on microbial stability and composition of flavor and healthful compounds - sugars, acids, volatiles, carotenoids, total phenolics, pectin and fiber – in citrus, tomato, and subtropical-bred small fruit breeding lines. 2. Relate chemical composition to sensory flavor and pathogen resistance data from Objective 1 to determine which compounds are important for flavor or have anti-microbial properties. a) Modeling for quality evaluation. b) Modeling for shelf life as limited by decay and identify natural compounds with antimicrobial activity. 3. Develop pre- and postharvest treatment protocols for reducing specific decay pathogens using sanitizers, antimicrobials, such as plant (including citrus) essential oils, with or without coatings and/or other surface treatments and storage atmospheres to minimize postharvest losses and maximize shelf life of the of citrus, tomato, berries and select tropicals for both intact and fresh-cut products. a) Pre-harvest treatments to reduce postharvest pathogens and to enhance postharvest quality. b) Postharvest treatments to prevent decay and transference of fruit surface microbes.

Approach:
Evaluate advanced breeding lines for citrus tomato and small fruits to determine optimal harvest maturity, microbial stability, and overall flavor quality. Evaluate diverse breeding material for citrus, tomato, and strawberry to determine desirable flavor aromas and tastes. Flavor analyses will be done using sensory panels as well as chemical analyses using gas chromatography (GC) mass spectroscopy (MS), GC-olfactometry, and electronic nose for aroma compounds and liquid chromatography (HPLC), HPLC-MS and microplate readers for sugars, acids, vitamin C, carotenoids, phenolic and antioxidant analyses coupled with flame ionization, refractive index and ultraviolet light and photo diode array among other detectors. Sensory panels will consist of consumer or trained descriptive panels to determine preference and fundamental flavor information. Multivariate and other statistics will be used to relate chemical to sensory data. Storage of commodities under study will be done using simulated commercial or abusive conditions for monitoring of quality and decay. Causal decay organisms will be indentified and pre- and postharvest treatments to reduce their population will be tested including pre-harvest deployment of wax-based sprays, sanitizers, and nutrients as well as use of postharvest sanitizers, anti-microbial agents or antagonists with or without coatings. Produce will also be subjected to short-term antimicrobial atmospheres of low oxygen, high carbon dioxide alone or combined with other anti-microbial volatile compounds. Effect of disease (Huanglongbing) on orange juice flavor will also be analyzed and identification and threshold of off-flavor compounds determined.

Last Modified: 10/30/2014
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