wizyta

od 2020-09-20

Title: Acid induced gelation of low methoxyl pectins studied by 1H NMR and rheological methods

Source: Applied Magnetic Resonance

Year : 2008

Abstract:

The various 1H NMR techniques (1H NMRD, water proton spin-spin relaxation time and diffusion measurements) in combination with rheological measurements were applied to the analysis of the acid induced gelation of 3% w/w aqueous LM pectin solutions at 279 K. A decrease of the pH value of solutions from 5 to 2.6 leads to a slowdown in the dynamics of the water molecules and to a substantial modification in the structure of the system studied. The most significant changes in the 1H NMRD and T2 measurements were observed when the pH was varied from 5 to 3, which reflected an increase in the stiffness of the pectin chains caused by non-ionic associations and by an increase of water molecules that were trapped between the pectin chains in the gelled ste. The results obtained by the rheological method are consistent with those of 1H NMR, indicating a solution-like mechanical response for the sample at pH 5 and a gel-like response at pH 3. Results of 1H NMR measurements have also shown an important role for aggregation processes of the LM pectin molecules in the acid-induced gel network formation.

DOI: 10.1007/s00723-008-0107-7   (Pobrane:  2020-10-21)