Retention of folates in cooked, stored and reheated peas, broccoli and potatoes for use in modern large-scale service systems

This study aimed to evaluate retention of folate in vegetables caused by different processes used in modern large-scale service systems and the food industry. The concentration of folates present in raw samples of peas, broccoli and potatoes was measured during different cooking methods, warm and cold holding and reheating. The main folate forms in vegetables, tetrahydrofolates and 5-methyltetrahydrofolates, were analysed using a validated high-performance liquid chromatography (HPLC) method.This study shows the following decreasing order in folate retention, on DM basis, compared to raw potatoes during heat-processing: sous-vide (103%), boiling (72–59% (unpeeled and peeled)) and oven-baking (63%) and compared to raw green peas during heat processing: boiling (77%), microwaving (75%), steam boiling (73%) and blanching (71%). However, only blanching of peas, boiling of potatoes and oven-baking of unpeeled potatoes caused significant reduction. Storage at various temperatures and length of times followed by reheating caused no further significant losses of total folate.