S25 - Session O2 - Agronomic and phytochemical characterization of Trigonella caerulea accessions

Authors: Manuel Pramsohler *, Alessia Castellan, Mayra Galarza Pérez, Serhat Sezai Ciçek

Trigonella caerulea (L.) Ser. is an annual herb belonging to the Fabaceae plant family. The aerial parts of T. caerulea are traditionally used in the Alpine Region for flavoring cheese (Switzerland) and bread (Italy), whereas the seeds are used in the Caucasus region as a spice. While the chemical composition of the seeds is well known, the chemical composition of the aerial parts of the plant is less well described. Alpha-keto acids are considered responsible for the characteristic aroma, but nothing is known about their quantity in the dried plant material. Thus, the aim of the present study was to analyze the agronomic traits and the phytochemical composition of seven accessions of T. caerulea harvested in South Tyrol (Italy). During the years 2020 and 2021 the seven accessions were grown in a randomized complete block design with three repetitions at a field site at 620 m altitude. The plants were sown in a greenhouse and ten plants per plot were transplanted in the field in May. The following agronomic traits were studied: plant height, fresh/dry weight, yield. Plants were harvested at full flowering and dried at 30 °C for seven days. For the analysis of alpha-keto acids 1.0 g of dried and ground plant material was defatted with n -hexane and extracted with methanol using pressurized solvent extraction. Quantification was performed with reference standards using UHPLC-MS/MS in the MRM mode and derivatisation with O -(2,3,4,5,6)-pentafluorobenzyloxime. The seven studied accessions showed a low agronomic variability. Yield of the dried herb amounted from 0,8 to 1,3 t/ha and did not show statistically significant differences between the accessions. In contrast, we found significant differences in the content of alpha-keto acids between the years of harvest as well as the different accessions. While in the year 2020 the total amount of alpha-keto acids was ranging from 52 to 98 mg/kg dried plant material, the harvest of the year 2021 was amounting 23 to 72 mg/kg, indicating also a relative difference of up to 300% between the different accessions. The differences in total content were mainly resulting from the three major acids glyoxylic acid, alpha-ketoglutaric acid, and pyruvic acid. However, we observed also compound-specific differences, as e.g. for pyruvic acid and alpha-ketobutyric acid. In conclusion the seven studied accessions showed similar agronomic traits but significant differences in the overall content and content pattern of the flavor-determining alpha-keto acids.