Effect of pectin methyl esterase (PME) and CaCl2 infusion on the cell integrity of fresh-cut and frozen-thawed mangoes: An NMR relaxometry study

This study describes the use of Nuclear Magnetic Resonance (NMR) relaxometry to understand the effect of pectin methyl esterase (PME) + CaCl2 infusion under different conditions on cell integrity of fresh-cut and frozen-thawed mangoes. Infusion experiments were performed at: atmospheric pressure, vacuum conditions of 50 kPa and 10 kPa. For NMR relaxometry experiments T2 (spin-spin relaxation time), T1 (spin-lattice-relaxation times) and 2D T1-T2 experiments were performed. Results showed that, as the severity of the vacuum treatment increased, the relaxation times changed significantly (p < 0.05). The number of compartments observed in 1-D relaxation spectra of fresh and frozen-thawed mangoes changed with different treatments. The changes in relaxation times were explained due to formation of a gel formed by the interaction of pectin and calcium. 2D T1-T2 relaxation maps showed that compartmentalization was retained after vacuum treatment even for frozen-thawed samples. The study showed that NMR relaxometry is a useful tool to analyze the cell integrity of mangoes exposed to different treatments.