Low resolution 1H NMR assignment of proton populations in pound cake and its polymeric ingredients

Based on a model system approach, five different proton populations were distinguished in pound cake crumb using one dimensional low resolution H-1 NMR spectroscopy. In free induction decay (FID) measurements, proton populations were assigned to (i) non-exchanging CH protons of crystalline starch, proteins and crystalline fat and (ii) non-exchanging CH protons of amorphous starch and gluten, which are in little contact with water. In Carr-Purcell-Meiboom-Gill (CPMG) measurements, three proton populations were distinguished. The CPMG population with the lowest mobility and the FID population with the highest mobility represent the same proton population. The two CPMG proton populations with the highest mobility were assigned to exchanging protons (i.e., protons of water, starch, gluten, egg proteins and sugar) and protons of lipids (i.e., protons of egg yolk lipids and amorphous lipid fraction of margarine) respectively. Based on their spin-lattice relaxation times (T-1), two dimensional H-1 NMR spectroscopy further resolved the two proton populations with the highest mobility into three and two proton populations, respectively. (c) 2013 Elsevier Ltd. All rights reserved.