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United States Department of Agriculture

Agricultural Research Service

Title: Significant Variation Exists among Laboratories Measuring Onion Bulb Quality Traits

Authors
item Havey, Michael
item Cantwell, Marita - UNIV OF CA, DAVIS
item Jones, Meriel - UNIV OF LIVERPOOL, UK
item Jones, Richard - SEMINIS VEG SEEDS, TX
item Schmidt, Norman - GEORGIA SOUTHERN UNIV, GA
item Uhlig, John - SEMINIS VEG SEEDS, TX
item Watson, J - SUNSEEDS, OR
item Yoo, Kil - TEXAS A&M UNIV

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 2, 2002
Publication Date: N/A

Interpretive Summary: Onion flavor (pungency) is a major quality attribute with many consumers demanding less pungent onions. In recent years, some growers and retailers have attempted to measure pungency of onions produced in different regions to guarantee a desired level of pungency. However there are few data on the variability among laboratories using standardized protocols to estimate relative levels of pungencies. Onion cultivars were grown in replicated trials at each three locations. Random samples of bulbs from each plot were harvested and shipped to at least three cooperating laboratories, each of which measured percent dry weights (%DW), soluble solids content (SSC), and pungencies using the same techniques. For all tests except one, laboratories always represented highly significant sources of variation for measurements of %DW, SSC, and pungency. Therefore, one cannot make recommendations on relative pungencies of the same lots of onions measured by different labs. We recommend that the onion research community develop specific procedures to reduce variation among laboratories and agree on a repeatable standardized assay for the measurement of onion pungency.

Technical Abstract: Onion pungency is a major quality attribute with many consumers demanding less pungent onions. In recent years, some growers and retailers have attempted to measure pungency of onions produced in different regions to guarantee a desired level of pungency. However there are few data on the variability among laboratories using standardized protocols to estimate relative levels of pungencies. Onion cultivars were grown in replicated trials at three locations. Random samples of bulbs from each experimental unit were harvested and shipped to at least three cooperating laboratories, each of which measured percent dry weights (%DW), soluble solids content (SSC), and pungencies using the same techniques. As expected, cultivars and locations often showed significant differences. For all tests except one, laboratories were always a highly significant source of variation (P<0.002) for measurements of %DW, SSC, and pungency. Therefore, one cannot make recommendations on relative pungencies of the same lots of onions measured by different labs. The onion research community must identify specific procedures to reduce variation among laboratories to develop a more repeatable standardized assay for the measurement of onion pungency.

Last Modified: 9/10/2014
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