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United States Department of Agriculture

Agricultural Research Service

2009 Annual Report

1a.Objectives (from AD-416)
The primary goals of this research project are to establish the role of naturally occurring biologically active citrus phytochemicals, in particular citrus limonoids, in human health and nutrition, to enhance citrus co-product utilization and to utilize molecular level methods to improve citrus quality and optimize important biologically active phytochemicals in new citrus varieties.

1b.Approach (from AD-416)
1) Characterize naturally occurring phytochemicals, in particular limonoids, isolated from citrus fruit and juice, and assess their biological activity, determine their potential contribution to the improvement of human health and nutrition, and establish the nature and scope of their action in biological systems. .
2) Develop and refine methodology to reclaim pure biologically active citrus limonoids important to human health and nutrition from citrus processing co-products. .
3) Determine the origins and modulating chemical and biochemical factors for natural phytochemicals in citrus and develop molecular level strategies to modify and/or enhance the character or amount of these compounds to achieve improve citrus quality, increased consumer acceptance and optimized nutritional value of citrus. Replaces 5325-41430-008-00D (01/2005).

3.Progress Report
The Metabolic Analysis of Mandarin Orange - For this project, we have continued our analysis of Satsuma mandarin orange juices obtained from 10 different orchards located in Placer County and expanded the scope of the study to include metabolite profiling and molecular analyses. Profiling experiments target carotenoids, limonoids and volatile juice components. Molecular analyses focused on the expression of enzymes in the synephrine biosynthetic pathway. No progress on the analyses yet.

The CDFA-Funded Citrus Project - This multi-step project consists of four steps that include the collection of citrus samples, primary analysis of physicochemical properties, metabolite profiling by both GC-MS and LC-MS, and data analysis. During the past growing session we have collected commercial samples of Navel, Valencia and Mandarin orange varieties from multiple locations throughout California and have completed the primary chemical analysis of these samples. Additionally, we have established schedules to collect additional samples during the coming months and have secured samples from Florida and the Citrus Variety Collection.

Trust - Efforts in support of this project have been directed at the continued recovery of limonin glucoside from available starting materials and the isolation and characterization of the degradation products resulting from the vitamin B2 catalyzed oxidation of limonin glucoside. Additionally, the evaluation and introduction of various pretreatment methods resulted in improved recovery efficiencies downstream and led to the recovery of enough limonin glucoside for testing on another four study participants.

1. Presence of Synephrine Verified in California-Grown Mandarin Oranges. Mandarin orange growers have been looking to increase consumer utilization of their product by identifying value-added biomolecules present in mandarin oranges. ARS researchers in the Processed Foods Research Unit, Albany, CA, determined that mandarin oranges contain significant levels of dietary synephrine. Synephrine is a bioactive molecule that has shown some promise as an aid to weight management and also possess decongestant properties. ARS researchers also determined intragrove and intergrove variability and the effect of storage on synephrine concentrations. Results from this study were distributed through a peer-reviewed article and were picked up by the popular press. Growers indicated that these outputs were instrumental in generating increased consumer demand and ultimately contributed to the growers selling out of their crop for the 2008-2009 season.

6.Technology Transfer

Number of Other Technology Transfer10

Review Publications
Dragull, K.D., Breksa III, A.P., Cain, B.R. 2008. Synephrine Content of Juice from Satsuma Mandarins (Citrus unshiu Marcovitch). Journal of Agricultural and Food Chemistry. 56:8874-8878.

Breksa III, A.P., Dragull, K.D. 2009. Development and Validation of a Decigram-Scale Method for the Separation of Limonin from Limonin Glucoside by C-18 Flash Chromatography. Food Chemistry. 113:1308-1311.

Breksa III, A.P., Hidalgo, M., Lee-Yuen, M. 2009. Liquid Chromatography-Electrospray Ionization Mass Spectrometry Method for the Rapid Identification of Citrus Limonoid Glucosides in Citrus Juices and Extracts. Journal of Food Chemistry. 117(4)739-744.

Last Modified: 10/22/2014
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