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|Type:||Artigo de periódico|
|Title:||Importance Of Cis-isomer Separation In Determining Provitamin A In Tomato And Tomato Products|
|Abstract:||An attempt was made to estimate the error in the determination of the vitamin A value (activity) when the cis- and trans-isomers are not separated and quantified individually. In 10 sample lots of fresh tomatoes, cis-isomers were not detected. However, in 52 samples of tomato products, varying amounts of cis-isomers of β-carotene were found. Utilising the currently employed calculation procedure, overestimations of 8-13% in juice, 10-66% in puree and paste, 15-26% in ketchup were observed when isomer separation was not undertaken. When column loss was taken into consideration, these errors decreased to 4-8%, 6-62% and 11-21%, respectively. Using the biopotencies obtained by Sweeney and Marsh (1970), aside from column loss, the overestimations were 4-8%, 3-52% and 7-15%, respectively. Thus, the error can be considerable, but the magnitude depends on how the calculation is carried out, demonstrating the necessity of establishing the true biopotencies, aside from obtaining more efficient chromatographic separation and accurate quantitation. © 1992.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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