Avaliação intralaboratorial do desempenho de analistas na análise de carotenoides utilizando material de referência certificado / Intralaboratory assessment of analysts’ proficiency for carotenoidanalysis using a certified reference material

Carotenoid analysis is inherently challenging, requiring the analysts’ expertise and attention to manydetails. To guarantee the reliability of carotenoid data generated in our laboratory, aside from methoddevelopment, optimization and validation, periodic evaluation of the analysts’ performance is carried out.This paper reports the results obtained in one of our evaluations, using a certified reference material. Fiveanalysts with varying experience in carotenoid analysis participated. The same liquid chromatograph andstandard curves were used, restricting the evaluation to the analysts’ performance. The HPLC methodconsisted of extraction with acetone, partition to petroleum ether, saponification with 10 % methanolicKOH, washing with water, concentrating in a rotary evaporator, drying with nitrogen, dissolving inacetone, separation, identification and quantification. The z-score for each carotenoid was calculated.There was very good agreement in terms of the carotenes and b-cryptoxanthin for the five analysts. Forlutein and zeaxanthin, the analyst with little experience in carotenoid analysis obtained lower values,but the z-scores were still satisfactory. One analyst who had experience only with carotene analysis alsogot lower concentrations for the xanthophylls. This was due to the fact that ethyl ether was not used inpartitioning the carotenoids from the extracting solvent to petroleum ether.

Teores de carotenóides em produtos de tomate / Carotenoid contents in Brazilian tomato products

A composição dos carotenóides em produtos de tomate foi anteriormente determinada em nosso laboratório, utilizando-se cromatografia em coluna aberta. Em virtude da introdução de novas variedades de tomate, do desenvolvimento de novos produtos e dos avanços tecnológicos nas áreas de processamento e de técnicas analíticas, esses dados necessitavam ser atualizados. Neste contexto, no presente estudo determinou-se a composição de carotenóides em produtos de tomates por meio de técnica CLAE. As amostras de extrato, catchup, polpa, molho pronto e tomate seco foram adquiridas em supermercados em Campinas-SP. Para cada produto, foram adquiridos cinco lotes diferentes de cada uma das três marcas (no total de 65 amostras), em que cada lote foi composto por três embalagens coletadas ao acaso. As faixas de licopeno e de β-caroteno total (μg/g) foram, respectivamente, 188-261 e 9,3-13 para extrato, 111-203 e 5,1-7,0 para catchup, 77-117 e 4,4-73 para polpa, 93-112 e 5,1-6,4 para molho pronto e 231-471 e 7,0-25 para tomate seco. O tomate seco, que foi analisado pela primeira vez, apresentou os maiores teores de licopeno e luteína. Os teores 2 de β-caroteno do extrato e licopeno do extrato e catchup foram maiores nas amostras analisadas neste estudo, quando comparados com os resultados obtidos no trabalho anterior.

The carotenoid contents in Brazilian tomato produc0ts were previously determined at our laboratory byusing raw material. The data regarding the development of new products, the advances on processingtechnologies and analytical techniques, need to be updated. In this context, the present study was carried out in order to determine the carotenoid contents of processed tomato products by means of HPLC. Samples of ketchup, sauce, paste, pulp and dried tomato were purchased at supermarkets in Campinas, Brazil. Foreach product, five different lots from each of the three brands (a total of 65 samples) were purchased, each lot consisting of three randomly collected packages. The lycopene and β-carotene concentration ranges (μg/g) were 188-261 and 9.3-13 for paste, 111-203 and 5.1-7.0 for ketchup, 77-117 and 4.4-7.3 for pulp, 93-112 and 5.1-6.4 for sauce, 231-471 and 7.0-25 for dried tomato, respectively. Dried tomatoes, which were analyzed for the first time, showed the highest lycopene and lutein concentrations. β-carotene contents in the paste and lycopene contents in tomato paste and in ketchup samples analyzed by the present study were higher than those obtained in the previous investigation.

Uncultivated Brazilian green leaves are richer sources of carotenoids than are commercially produced leafy vegetables.

BACKGROUND: With the continuing problem of vitamin A deficiency, the recognition of the role of carotenoids in disease prevention, and international programs promoting biodiversity, determination of the carotenoid content of indigenous Brazilian foods is needed. OBJECTIVE: To determine the principal carotenoids in native leaves and compare the levels with those in commercially produced leafy vegetables. METHODS: The indigenous Brazilian leafy vegetables caruru, mentruz, taioba, serralha, and beldroega were analyzed with the use of a previously developed and validated high-performance liquid chromatography (HPLC) method. Parsley and coriander leaves, which were previously shown to be the richest in carotenoids among commercially produced leaves, were analyzed for comparison. Five sample lots of each vegetable collected at different times during the year were analyzed immediately after harvest. RESULTS: Lutein concentrations were 119 +/- 21, 111 +/- 48, 104 +/- 44, 87 +/- 7, and 34 +/- 14 microg/g, and beta-carotene contents were 114 +/- 22, 97 +/- 40, 66 +/- 18, 72 +/- 9, and 32 +/- 14 microg/g for caruru, mentruz, taioba, serralha, and beldroega, respectively. Except for beldroega, these values were higher than those for commercial leaves. Parsley had 88 +/- 18 microg/g of lutein and 65 +/- 13 microg/g of beta-carotene. Coriander leaves contained 74 +/- 6 microg/g of lutein and 55 +/- 5 microg/g of beta-carotene. The violaxanthin and neoxanthin concentrations were also higher in the native leaves. Comparison with values for previously analyzed commercial leafy vegetables confirmed the higher carotenoid levels of the native leaves. CONCLUSIONS: The indigenous leaves investigated are richer sources of carotenoids than are commercially produced leafy vegetables.