Faculty of Food Sciences, University of Warmia and Mazury in Olsztyn, 10-957 Olsztyn, Poland.
Plant Foods Hum Nutr. 2012 Dec;67(4):401-6. doi: 10.1007/s11130-012-0312-2.
Folates (B vitamins) are essential for the proper function of many bodily processes. Although a rich natural source are vegetables, the literature lacks data on the effect of the pre-treatment and freezing technologies used in vegetable processing and frozen storage time on the folate content in these materials. Moreover, since folates are very unstable nutrients, the amount available in processed and stored foods can be significantly lower than in raw products. In tested vegetables (green beans, yellow beans, peas, cauliflower, broccoli and spinach), one folate form was identified, 5-methyltetrahydrofolate (5-CH₃-H₄folate). It was observed that pre-treatment and freezing technology significantly (p < 0.05) decreased 5-CH₃-H₄folate content only in vegetables with the largest degree of fragmentation (cut and briquetted spinach) and the smallest size (peas). In all analyzed samples, the 5-CH₃-H₄folate content decreased with the time of frozen storage. In frozen cauliflower, the 5-CH₃-H₄folate loss exceeded 95 % compared to the fresh product just after the third month of frozen storage. Meanwhile, in green and yellow beans, significant 5-CH₃-H₄folate losses (at the level of 75 % and 95 %, respectively) were observed no earlier than after the 9th month of frozen storage.
叶酸（B 族维生素）是许多身体机能正常运作所必需的。虽然蔬菜是叶酸的丰富天然来源，但文献中缺乏关于蔬菜加工过程中预处理和冷冻技术以及冷冻储存时间对这些材料中叶酸含量影响的数据。此外，由于叶酸是非常不稳定的营养物质，加工和储存食品中的可用量可能明显低于生产品。在所测试的蔬菜（青豆、黄豌豆、豌豆、花椰菜、西兰花和菠菜）中，确定了一种叶酸形式，即 5-甲基四氢叶酸（5-CH₃-H₄folate）。研究发现，预处理和冷冻技术仅显著（p<0.05）降低了碎裂程度最大（切碎和压块的菠菜）和尺寸最小（豌豆）的蔬菜中的 5-CH₃-H₄folate 含量。在所有分析的样本中，5-CH₃-H₄folate 含量随冷冻储存时间的延长而降低。在冷冻花椰菜中，与刚收获的新鲜产品相比，在冷冻储存第三个月后，5-CH₃-H₄folate 的损失超过 95%。相比之下，在青豆和黄豌豆中，5-CH₃-H₄folate 的大量损失（分别为 75%和 95%）直到冷冻储存第 9 个月后才观察到。
