Delchier Nicolas, Ringling Christiane, Maingonnat Jean-François, Rychlik Michael, Renard Catherine M G C
INRA, UMR408 Sécurité et Qualité des Produits d'Origine Végétale, Domaine Saint Paul, Site Agroparc, F-84000 Avignon, France; Université d'Avignon et des Pays du Vaucluse, UMR408 Sécurité et Qualité des Produits d'Origine Végétale, F-84000 Avignon, France.
Bioanalytik Weihenstephan, Research Center of Nutrition and Food Sciences, Technische Universität München, Alte Akademie 10, D-85354 Freising, Germany.
Food Chem. 2014 Aug 15;157:439-47. doi: 10.1016/j.foodchem.2014.02.054. Epub 2014 Feb 22.
Though folates are sensitive to heat treatments, leaching appears to be a major mechanism involved in folate losses in vegetables during processing. The aim of our study was to study folate diffusivity and degradation from spinach and green beans, in order to determine the proportion of each mechanism involved in folate losses. Folate diffusivity constant, calculated according to Fick's second law (Crank, 1975), was 7.4×10(-12) m(2)/s for spinach and 5.8×10(-10) m(2)/s for green beans, which is the same order of magnitude as for sugars and acids for each vegetable considered. Folate thermal degradation kinetics was not monotonous in spinach and green beans especially at 45 °C and did not follow a first order reaction. The proportion of vitamers changed markedly after thermal treatment, with a better retention of formyl derivatives. For spinach, folate losses were mainly due to diffusion while for green beans thermal degradation seemed to be preponderant.
尽管叶酸对热处理敏感，但沥滤似乎是蔬菜加工过程中叶酸损失的主要机制。我们研究的目的是研究菠菜和青豆中叶酸的扩散率和降解情况，以确定每种机制在叶酸损失中所占的比例。根据菲克第二定律（Crank，1975）计算得出，菠菜的叶酸扩散常数为7.4×10(-12) m(2)/s，青豆为5.8×10(-10) m(2)/s，这与所考虑的每种蔬菜中糖和酸的扩散常数处于同一数量级。菠菜和青豆中的叶酸热降解动力学并非单调，尤其是在45°C时，且不遵循一级反应。热处理后维生素形式发生了显著变化，甲酰基衍生物的保留情况较好。对于菠菜，叶酸损失主要是由于扩散，而对于青豆，热降解似乎占主导地位。
