Pharmacognosy department, College of Pharmacy, Cairo University, Kasr el Aini St., Cairo 11562, Egypt.
Department of Chemistry, School of Sciences & Engineering, The American University in Cairo, New Cairo 11835, Egypt.
Molecules. 2019 Mar 7;24(5):928. doi: 10.3390/molecules24050928.
Brine, the historically known food additive salt solution, has been widely used as a pickling media to preserve flavor or enhance food aroma, appearance, or other qualities. The influence of pickling, using brine, on the aroma compounds and the primary and secondary metabolite profile in onion bulb red cv. and lemon fruit was evaluated using multiplex metabolomics technologies. In lemon, pickling negatively affected its key odor compound "citral", whereas monoterpene hydrocarbons limonene and γ-terpinene increased in the pickled product. Meanwhile, in onion sulphur rearrangement products appeared upon storage, i.e., 3,5-diethyl-1,2,4-trithiolane. Profiling of the polar secondary metabolites in lemon fruit via ultra-performance liquid chromatography coupled to MS annotated 37 metabolites including 18 flavonoids, nine coumarins, five limonoids, and two organic acids. With regard to pickling impact, notable and clear separation among specimens was observed with an orthogonal projections to least squares-discriminant analysis (OPLS-DA) score plot for the lemon fruit model showing an enrichment of limonoids and organic acids and that for fresh onion bulb showing an abundance of flavonols and saponins. In general, the pickling process appeared to negatively impact the abundance of secondary metabolites in both onion and lemon, suggesting a decrease in their food health benefits.
盐水，作为历史上已知的食品添加剂盐溶液，被广泛用作腌制媒介，以保持风味或增强食物的香气、外观或其他品质。本研究采用多元代谢组学技术评估了腌制（使用盐水）对洋葱鳞茎红皮品种和柠檬果实中香气化合物以及主要和次要代谢物谱的影响。在柠檬中，腌制对其关键气味化合物“柠檬醛”产生负面影响，而单萜烃柠檬烯和γ-萜品烯在腌制产品中增加。同时，在洋葱中，储存过程中出现了硫重排产物，即 3,5-二乙基-1,2,4-三硫杂环戊烷。通过超高效液相色谱-质谱联用技术对柠檬果实中的极性次生代谢物进行分析，共鉴定出 37 种代谢物，包括 18 种类黄酮、9 种香豆素、5 种柠檬苦素和 2 种有机酸。就腌制的影响而言，柠檬果实模型的正交投影偏最小二乘法判别分析（OPLS-DA）得分图中观察到样本之间的明显和清晰分离，表明柠檬苦素和有机酸的富集，而新鲜洋葱鳞茎模型中则显示出类黄酮和皂苷的丰富。总的来说，腌制过程似乎对洋葱和柠檬中次生代谢物的丰度产生负面影响，表明其食用健康益处减少。
