Effect of Germination and Thermal Treatments on Folates in Rye

Abstract

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.

Content of Vitamins B1 and B2 in Germinating Grain

“…A maximum 3.6-fold folate concentration in the sprouted wheat and 1.7-3.8-fold in sprouted rye were obtained on day 5 of germination [8,9]. The total folate concentration remained above the baseline after subsequent heat treatment of sprouted rye [8].…”

“…A maximum 3.6-fold folate concentration in the sprouted wheat and 1.7-3.8-fold in sprouted rye were obtained on day 5 of germination [8,9]. The total folate concentration remained above the baseline after subsequent heat treatment of sprouted rye [8]. However, the data were presented on substantial reduction in vitamin B 1 content after 3 days of germination in corn and oats [6].…”

Effect of germination and subsequent oven-drying on folate content in different wheat and rye cultivars

“…The B-vitamin folate is essential for cell replication and occurs naturally in cereal-based foods. Germinated cereals are reported to be an even richer folate source (Kariluoto et al, 2006;Koehler et al, 2007;Hefni and Witthöft, 2011), because of de novo synthesis of folate in the growing seedling (Jabrin et al, 2003).…”

The Magic and Challenges of Sprouted Grains

“…According to EU Regulation (EC) No. 1924No. /2006 it is possible to claim that sprouted grains are a "source of fibers" or are "rich in fibers" depending on their fiber content.…”

“…However, when looking at the existing scientific evidence, the results are mixed (28), and the published studies are difficult to compare because the types and varieties of grains, soaking conditions (water quality), germination conditions (duration and temperature), and measurement methods differ from one study to another. Several studies (8,9,13,14,17,(19)(20)(21)(22)27,31,(36)(37)(38)(39) reported an increase in the levels of some vitamins and minerals with sprouting, while other studies reported no impact or even reduced levels of some vitamins and minerals (2,8,9,17,19,30,31,35). A summary of the results observed for two vitamins, B 9 and E, across various studies is provided in Table I.…”