Abstract：
Boiled lotus rhizome discs (BLRDs), as common processed products of lotus rhizome, have gained increasing attention from consumers and food manufacturers. However, the blue pigment formed during boiling affects its appearance and reduces the appetite of BLRDs. In this study, the effects of polyphenols and iron contents on blue pigment formation in BLRDs in different regions and months were investigated. Results revealed that blue variation was more serious in March and April of the second year in Wuhan, and polyphenols and iron contents in these two months were significantly higher than those in other months. Then, UPLC and UV-Vis analysis showed that polyphenols causing the formation of blue pigment in BLRDs were L-dopa, gallocatechin, catechin, epigallocatechin, chlorogenic acid and epicatechin, among which L-dopa (52.450 mg/100 g in fresh lotus rhizome (FLR)) and gallocatechin (36.210 mg/100 g in FLR) possessed the greatest effect. Moreover, the ESI-Q-TOF-MS analysis of L-dopa-iron chelate and gallocatechin-iron chelate suggested that the blue pigment of BLRDs was mainly in the form of bis-complexes under boiling conditions. The study on formation mechanism of blue pigment in BLRDs can provide a reference for lotus rhizome processing.
摘要：
水煮莲花根茎盘（BLRD），作为莲花的常见加工产品，越来越受到消费者和食品制造商的关注。然而,沸腾过程中形成的蓝色颜料会影响其外观并降低BLRD的食欲。在这项研究中,研究了多酚和铁含量对不同地区和月份BLRD中蓝色色素形成的影响。结果表明，武汉市第二年的3月和4月蓝色变异较为严重，这两个月的多酚和铁含量明显高于其他月份。然后，UPLC和UV-Vis分析表明，导致BLRD中蓝色色素形成的多酚是左旋多巴，gallocatechin,儿茶素,表没食子儿茶素，绿原酸和表儿茶素，其中左旋多巴（新鲜莲花根茎（FLR）为52.450mg/100g）和gallocatechin（FLR为36.210mg/100g）的作用最大。此外，L-多巴-铁螯合物和半乳糖儿茶素-铁螯合物的ESI-Q-TOF-MS分析表明，BLRD的蓝色颜料在沸腾条件下主要呈双配合物形式。对BLRDs中蓝色色素形成机理的研究可为莲花根茎加工提供参考。
