Effect of germination and thermal treatments on folates in rye.
Effects of germination conditions and thermal processes on folate contents of rye were investigated. Total folate contents were determined microbiologically with Lactobacillus rhamnosus (ATCC 7469) as the growth indicator organism, and individual folates were determined by high-performance liquid chromatography after affinity chromatographic purification. Germination increased the folate content by 1.7-3.8-fold, depending on germination temperature, with a maximum content of 250 micro g/100 g dry matter. Hypocotylar roots with their notably high folate concentrations (600-1180 micro g/100 g dry matter) contributed 30-50% of the folate contents of germinated grains. Germination altered the proportions of folates, increasing the proportion of 5-methyltetrahydrofolate and decreasing the proportion of formylated folate compounds. Thermal treatments (extrusion, autoclaving and puffing, and IR and toasting) resulted in significant folate losses. However, folate levels in grains that were germinated and then were heat processed were higher than for native (nongerminated) grains. Opportunities to optimize rye processing to enhance folate levels in rye-based foods are discussed.
Kariluoto
Susanna
S
Viikki Food Science, Department of Applied Chemistry and Microbiology, FIN-00014, University of Helsinki, Finland. susanna.kariluoto@helsinki.fi
Liukkonen
Kirsi-Helena
KH
Myllymäki
Olavi
O
Vahteristo
Liisa
L
Kaukovirta-Norja
Anu
A
Piironen
Vieno
V
D005492:Folic Acid / Q000032:analysis*; D018525:Germination / Q000502:physiology*; D006358:Hot Temperature; D018517:Plant Roots / Q000737:chemistry; D012434:Secale / Q000737:chemistry*; D012639:Seeds / Q000737:chemistry*
D005492:Folic Acid