Effects of blanching on polyphenol stability of innovative paste-like parsley (Petroselinum crispum (Mill.) Nym ex A. W. Hill) and marjoram (Origanum majorana L.) products

Fresh herbs were water- and steam-blanched at 90–100 °C and 100 °C, respectively, for 1–10 min and 30 s to 7 min for parsley and marjoram, respectively, and subsequently minced to obtain a paste. For the first time, phenolic compounds of unheated marjoram were characterised by high-performance liquid chromatography coupled to mass spectrometry (HPLC–MS). Hereby, 10 phenolics were detected. Among them, apigenin-glucuronide, lucenin-2 and lithospermic acid were tentatively identified for the first time. In unheated parsley, apart from the major compound apiin, 10 further phenolics were characterised including several p-coumaric acid derivatives which were newly detected. Except for apiin, short-time steam- and water-blanching (1 min), respectively, did not cause significant losses of phenolic compounds, and thus proved to be the most suitable measures to ensure polyphenol retention. Consequently, blanching is a recommendable initial operation in the processing of parsley and marjoram into novel paste-like products.