Folate retention in nuts and seeds – Effects of household cooking

Abstract

Folate is a water-soluble vitamin known as being sensitive to various conditions, but little is known about its stability during household cooking. The effect of heat treatments, simulating household cooking, on the folate content and retention of folate was studied. In addition, the effect of exposure of the solution of folate vitamers to daylight, yellow and UVB light was studied as well. Nuts (almonds, hazelnuts, and peanuts) and seeds (pumpkin, sesame, and sunflower seeds) were boiled (100 °C, 5–60 min) and/or roasted (175 °C, 2–15 min) in three independent processes. Six folate vitamers were extracted by single-enzymatic step and quantified by liquid chromatography tandem mass spectrometry (LC-ESI-MS/MS). Light had no significant effect on folate stability (p > 0.05). Total folate retention was on average 81% ± 7% ranging from 71% in roasted hazelnuts to 92% in boiled sesame seeds. The retention of total folate and specific vitamers depended on the food type and processing (p ≤ 0.05). Folic acid and formyl forms were more stable than 5-methyltetrahydrofolate and tetrahydrofolate. An average retention of formyl forms and folic acid in nuts was not significantly different from 100%. The data enable correction and better understanding of folate dietary intake from thermally processed nuts and seeds.