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Water and oil signal assignment in low‐moisture mozzarella as determined by time‐domain NMR T 2 relaxometry
Author(s) -
Vermeir Lien,
Declerck Arnout,
To Chak Ming,
Kerkaert Barbara,
Van der Meeren Paul
Publication year - 2019
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.4842
Subject(s) - chemistry , relaxometry , mozzarella cheese , moisture , relaxation (psychology) , water content , bonito , t2 relaxation , deuterium , proton nmr , matrix (chemical analysis) , analytical chemistry (journal) , nuclear magnetic resonance , chromatography , food science , magnetic resonance imaging , organic chemistry , fish <actinopterygii> , psychology , social psychology , physics , geotechnical engineering , spin echo , quantum mechanics , engineering , radiology , fishery , biology , medicine
A time‐domain 1 H nuclear magnetic resonance relaxometry method was elaborated for the rapid microstructural characterization of mozzarella cheese. For this purpose, there is a strong need to know how the experimentally determined T 2 relaxation time distribution can be related to specific constituents in mozzarella. In this study, a detailed investigation is offered for fresh and aged low‐moisture mozzarella cheese, often applied as a pizza cheese, by application of both a conventional Carr–Purcell–Meiboom–Gill (CPMG) sequence and a free‐induction decay CPMG (FID‐CPMG) sequence. The relaxation behavior was further elucidated by addition of deuterium oxide and by mild heat treatment of samples. The relaxation times of water protons in mozzarella were found to range from a few microseconds to some tens of milliseconds (in aged mozzarella) or to about hundred milliseconds (in fresh mozzarella). The upper limit of the T 2 distribution can even be extended to the seconds range upon releasing water protons from the mozzarella matrix using a mild heat treatment or upon addition of deuterated water. Both stimuli also provided evidence for the absorption of water into the cheese matrix. The potential release and uptake of water demonstrated that mozzarella acts as a very dynamic system during production and storage. The detected differences in the behavior of the water fraction between fresh and aged low‐moisture mozzarella might be utilized to study the influence of either production and/or storage conditions on the cheese ripening process.