Characterization of water mobility in biscuit dough using a low-field 1H NMR technique

Biscuit dough is a complex system containing numerous components in different states, such as starch, gluten, lipids (flour constituents), sugars, fats and water. Proton mobility in these dough systems was studied using low field 1H nuclear magnetic resonance (NMR). Transverse relaxation times (T2) were obtained from single pulse (FID) and Carr-Purcell-Meiboom-Gill (CPMG) experiments. Four populations can be distinguished: the first population observed with FID sequence at T2s*∼11 μs, corresponds to flexible protons associated with the crystalline phase of palm oil, starch and gluten; the other three populations which are measured with CPMG sequence are observed at T2(1)∼2 ms, T2(2)∼12 ms and T2(3)∼105 ms. The population (1) corresponds to intra-granular protons while the population (2) which is more sensitive to moisture and sucrose content, is attributed to protons in interaction with sucrose and starch. The protons of water are assumed to be distributed between these two populations. The population (3) is associated with apolar protons corresponding to the fat fraction present in the biscuit dough formula.