| Abstract
| - Bioavailability of dietary folate might be impaired by the polyglutamate chain to which ∼70% of dietaryfolates are bound. This chain must be removed enzymatically in the intestine before folate is absorbedas a monoglutamate. To increase formation of monoglutamate folate in vegetables, the vegetableswere subjected to various processing treatments. Treatments included freezing (−18 °C, 16 h) andthawing (4 °C, 24 h) and hydrostatic high-pressure treatment (200 MPa, 5 min). Both freezing/thawingand high-pressure treatment increased the proportion of folate in the monoglutamate form in leeks,cauliflower, and green beans 2−3-fold. However, loss of total folate after these treatments was >55%.It is concluded that conversion of folate polyglutamate to the monoglutamate form in vegetables ispossible by certain processing treatments. Potentially this could lead to vegetables with higher folatebioavailability. However, to prevent folate loss into processing water, processing in a closed systemshould be applied. Keywords: Folate; monoglutamate; polyglutamate; processing; freezing; high-pressure treatment;blanching; steaming; vegetables
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