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Folates in berries

evaluation of an RPBA method to study the effects of cultivar, ripeness, storage and processing

Strålsjö, Lena (2003). Folates in berries. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae. Agraria, 1401-6249 ; 368
ISBN 91-576-6197-9
[Doctoral thesis]

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Folate concentrations in berries and berry products were investigated, determining folate retention from raw material to the final product. Folate content was quantified using a modified and systematically evaluated radioprotein-binding assay (RPBA). The optimised RPBA was demonstrated to be a useful method for folate quantification in berries containing mainly 5-CH₃-H₄folate. Results after internal evaluation regarding selectivity, background radiation, unspecific binding, and accuracy are presented. To avoid unspecific binding purification of sample extracts by solid phase extraction prior to quantification was included for some berries. Microbiological assay (MA) and high performance liquid chromatography (HPLC) were used to compare obtained folate concentrations and to characterise individual folate forms in tested matrices. The predominating folate form in all tested berries was 5-CH₃-H₄folate. Therefore, the recently commercially available natural form (6S)-5-CH₃-H₄folate was chosen as calibrant. Berries rich in folate were rosehips (100-180 µg/100g fresh weight) and strawberries (70-90 µg/100g fresh weight). These two model berries were used to study factors affecting the folate content in berries. Significant effects on folate content were observed from cultivar, grade of ripeness and year of harvest. Folate retention in the two model berries was studied during storage, drying procedures and in commercial products. After storage of fresh strawberries in the refrigerator high folate retention was obtained, whereas storage in room temperature and at exposure to light resulted in folate losses. In rosehips folate retention during various drying procedures was improved by minimising the drying time using high temperature and cutting of berries into slices. Water content affected the stability of both folates and ascorbic acid during drying. Almost no folate losses occurred when strawberries were cooked as jam or stewed as strawberry desserts from frozen berries, with a folate retention of 79-103%. Commercial products from both berries contained 10-20 µg of folate per 100 g FW. Berries and semi-manufactures of berries are suitable ingredients in various food products to increase their nutritional value regarding folate intake. A newly developed human ileostomy model suitable for evaluating folate bioavailability from these products is presented. Increased intake of berries and berry products could well be an alternative to folate supplements and fortification.

Authors/Creators:Strålsjö, Lena
Title:Folates in berries
Subtitle:evaluation of an RPBA method to study the effects of cultivar, ripeness, storage and processing
Series Name/Journal:Acta Universitatis Agriculturae Sueciae. Agraria
Year of publishing :February 2003
Number of Pages:58
ALLI.Strålsjö, L., Arkbåge, K., Witthöft C.M., and Jägerstad, M. (2002) Evaluation of a radioprotein-binding assay (RPBA) for folate analysis in berries and milk. Food Chemistry 79(4) 525-534 II. Strålsjö, L., Åhlin, H., Witthöft, C.M., and Jastrebova, J. Folate determination in berries by radioprotein-binding assay (RPBA) and high performance liquid chromatography (HPLC). Accepted for publication in European Food Research and Technology III. Strålsjö, L., Witthöft, C.M., Sjöholm, I., and Jägerstad, M. Folate content in strawberries (Fragaria x ananassa) - effects of cultivar, year of harvest, ripeness, storage and commercial processing (2003). Journal of Agricultural and Food Chemistry 51(1) 128-133 IV. Strålsjö, L., Alklint, C., Olsson, M.E., and Sjöholm, I. Folate content and retention in rosehips (Rosa ssp) after drying. Manuscript to be submitted. V. Witthöft, C.M., Strålsjö, L., Berglund, G., and Lundin, E. A human model to determine folate bioavailability from food - a pilot study for evaluation. Accepted for publication in Scandinavian Journal of Nutrition vol 1/2003.
Place of Publication:Uppsala
Associated Programs and Other Stakeholders:Z - SLU - Library > Odla mera
ISBN for printed version:91-576-6197-9
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:S Human nutrition > S20 Physiology of human nutrition
Q Food science > Q04 Food composition
Subjects:Not in use, please see Agris categories
Agrovoc terms:folic acid, strawberries, soft fruits, proximate composition, food technology, human nutrition
Keywords:folic acid, 5-methyl-tetrahydrofolate, radioprotein-binding assay, folate retention, strawberries, rosehips, folate bioavailability, method evaluation
Permanent URL:
ID Code:159
Department:(NL, NJ) > Dept. of Food Science (until 161231)
Deposited By: Lena Strålsjö
Deposited On:10 Feb 2003 00:00
Metadata Last Modified:22 Mar 2015 15:09

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