Isothiocyanates (ITC) play an important role in health promotion and cancer prevention due to their anti-bacterial, anti-inflammatory, and anti-cancerogenic properties. However, ITC are highly reactive so that a reaction with further food components is very likely. For example, a reaction of ITC with nucleophilic amino acid side chains of proteins such as cysteine and lysine can occur, reducing the bioavailability of indispensable amino acids and protein functions may be altered. Therefore, it is of great interest to investigate the fate of ITC in the food matrix. Accordingly, the aim of the present study was to investigate the interaction of milk proteins and the ITC benzyl isothiocyanate (BITC) and allyl isothiocyanate (AITC) forming dithiocarbamates and thioureas in milk and curd. After incubating milk and curd with pure ITC or ITC-containing garden cress (Lepidium sativum L.), proteins were isolated, digested, and analyzed via LC-ESI-MS/MS as amino acid derivatives (“conjugates”). Protein conjugates of AITC and BITC were detected in all samples investigated. Further, the acidic pH value in curd favored the formation of dithiocarbamates over the formation of thioureas. Slightly acidic or neutral conditions like in fresh milk favored the formation of thioureas. The investigations also indicated that AITC shows a higher reactivity and dithiocarbamates are formed preferably, whereas incubation with BITC lead to less protein conjugates and the ratio of thioureas and dithiocarbamates was more balanced. In addition, amino acid modifications were often analyzed with indirect methods like measuring the decline of the amino acid residues. In this study, the modified amino acids were analyzed directly leading to more reliable results concerning the amount of modification.

异硫氰酸盐（ITC）由于具有抗菌，消炎和抗癌的特性，因此在健康促进和癌症预防中起着重要作用。但是，ITC具有很高的反应活性，因此很可能与其他食品成分发生反应。例如，可能发生ITC与蛋白质（例如半胱氨酸和赖氨酸）的亲核氨基酸侧链的反应，从而降低了必不可少的氨基酸的生物利用度，并可能改变蛋白质的功能。因此，研究ITC在食物基质中的命运非常重要。因此，本研究的目的是研究牛奶蛋白与ITC异硫氰酸苄酯（BITC）和异硫氰酸烯丙酯（AITC）的相互作用，从而在牛奶和凝乳中形成二硫代氨基甲酸酯和硫脲。番茄L.），将蛋白质分离，消化并通过LC-ESI-MS / MS作为氨基酸衍生物（“结合物”）进行分析。在所有调查的样品中都检测到了AITC和BITC的蛋白质结合物。此外，凝乳中的酸性pH值比硫脲的形成更有利于二硫代氨基甲酸酯的形成。像在鲜牛奶中那样的弱酸性或中性条件有利于硫脲的形成。研究还表明，AITC表现出较高的反应性，并且优选形成二硫代氨基甲酸酯，而与BITC的孵育会导致较少的蛋白质结合物，并且硫脲和二硫代氨基甲酸酯的比例更加平衡。此外，经常通过间接方法（例如测量氨基酸残基的下降）来分析氨基酸修饰。在这项研究中，