Novel Intelligent Detection of Safer Water Activity by LF-NMR Spectra for Selected Fruits and Vegetables during Drying

This study investigated the water status provided by LF-NMR spectra measurements for selected fruits (apple and carrot) and vegetables (white cabbage, cauliflower, and radish) during drying with or without sugar or salt treatment. Different shapes of the spectrum for different items and one to four peaks for different stages of drying were observed. A distinct different T-21 peak was observed for every sample when a(w) was less than 0.6. This prominent peak observed at less than 1ms relaxation time enabled us to conclude that the product a(w) is less than 0.6. A completely different effect of sugar and salt on LF-NMR spectra were also reported. A strong correlation between a(w) and total area (A(T)) was observed with the correlation coefficient=0.695 to 0.971.