25. Fast Sampling, Analyses and Chemometrics for Plant Breeding: Bitter Acids, Xanthohumol and Terpenes in Lupulin Glands of Hops (Humulus lupulus)

Daniel P. Killeen, Oliver C. Watkins, Catherine E. Sansom, David H. Andersen, Keith C. Gordon and Nigel B. Perry, Phytochemical Analysis, (2016), 28, 50–57, DOI: 10.1002/pca.2642

Lupulin glands from 139 plants (39 cultivars/advanced selections) were analysed by Raman and 1H NMR spectroscopy, and head-space solid-phase microextraction (HS-SPME) GC-FID. The digital X,Y-data were subjected to principal component analysis (PCA) and the results compared with conventional analyses of extracts of whole hops from the same plants. Quantitative 1H NMR analyses were also done for the bitter acids.

Raman spectroscopy rapidly identified hops cultivars with high xanthohumol concentrations and high a:ß bitter acid ratios. 1H NMR spectroscopy was slower, requiring a solvent extraction, but distinguished cultivars by cohumulone content as well as a:ß acid ratios. HS-SPME-GC rapidly distinguished aroma hops with high myrcene and farnesene contents, and pinpointed a novel selection with unusual sesquiterpenes. The quantitative NMR analyses showed correlations between bitter acid concentrations related to biosynthetic pathways.