Kyriacou Marios C, El-Nakhel Christophe, Pannico Antonio, Graziani Giulia, Soteriou Georgios A, Giordano Maria, Palladino Mario, Ritieni Alberto, De Pascale Stefania, Rouphael Youssef
Department of Vegetable Crops, Agricultural Research Institute, 1516 Nicosia, Cyprus.
Department of Agricultural Sciences, University of Naples Federico II, 80055 Portici, Italy.
Antioxidants (Basel). 2020 Mar 20;9(3):252. doi: 10.3390/antiox9030252.
The present study examined the modulatory effects of natural fiber substrates (agave fiber, coconut fiber and peat moss) and synthetic alternatives (capillary mat and cellulose sponge) on the nutritive and phytochemical composition of select microgreens species (coriander, kohlrabi and pak choi) grown in a controlled environment. Polyphenols were analyzed by UHPLC-Q-Orbitrap-HRMS, major carotenoids by HPLC-DAD, and macro-minerals by ion chromatography. Microgreens grown on peat moss had outstanding fresh and dry yield but low dry matter content. Natural fiber substrates increased nitrate and overall macro-mineral concentrations in microgreens compared to synthetic substrates. The concentrations of chlorophylls, carotenoids and ascorbate were influenced primarily by species. On the contrary, variability in polyphenols content was wider between substrates than species. Out of twenty phenolic compounds identified, chlorogenic acid and quercetin-3--rutinoside were most abundant. Hydroxycinnamic acids and their derivatives accounted for 49.8% of mean phenolic content across species, flavonol glycosides for 48.4% and flavone glycosides for 1.8%. Peat moss provided optimal physicochemical conditions that enhanced microgreens growth rate and biomass production at the expense of phenolic content. In this respect, the application of controlled stress (eustress) on microgreens growing on peat moss warrants investigation as a means of enhancing phytochemical composition without substantial compromise in crop performance and production turnover. Finally, nitrate deprivation practices should be considered for microgreens grown on natural fiber substrates in order to minimize consumer exposure to nitrate.
本研究考察了天然纤维基质（龙舌兰纤维、椰纤维和泥炭藓）及合成替代物（毛细管垫和纤维素海绵）对在可控环境中种植的选定微型蔬菜品种（香菜、球茎甘蓝和小白菜）营养及植物化学成分的调节作用。采用超高效液相色谱-四极杆-轨道阱-高分辨质谱法分析多酚，采用高效液相色谱-二极管阵列检测法分析主要类胡萝卜素，采用离子色谱法分析常量矿物质。在泥炭藓上生长的微型蔬菜具有出色的鲜重和干重产量，但干物质含量较低。与合成基质相比，天然纤维基质增加了微型蔬菜中的硝酸盐及总体常量矿物质浓度。叶绿素、类胡萝卜素和抗坏血酸的浓度主要受品种影响。相反，不同基质间多酚含量的变异性比不同品种间更大。在鉴定出的20种酚类化合物中，绿原酸和槲皮素-3-芸香糖苷最为丰富。羟基肉桂酸及其衍生物占各品种平均酚类含量的49.8%，黄酮醇糖苷占48.4%，黄酮糖苷占1.8%。泥炭藓提供了最佳的理化条件，提高了微型蔬菜的生长速率和生物量产量，但以酚类含量为代价。在这方面，对在泥炭藓上生长的微型蔬菜施加可控胁迫（良性应激）作为一种在不显著影响作物性能和生产周转的情况下提高植物化学成分的方法值得研究。最后，对于在天然纤维基质上生长的微型蔬菜，应考虑采用硝酸盐剥夺措施，以尽量减少消费者接触硝酸盐。
