Background: Hardness is one of the important qualities influencing consumer appeal and marketing of fresh sweet cherry (Prunus avium L.). Moisture loss is one of the main causative factors of cherry softening. In this work, moisture loss and softening process of sweet cherry during postharvest storage at 0 and 4 °C were studied. In addition, low-field 1 H nuclear magnetic resonance (LF-NMR) was used to analyze water distribution and migration in sweet cherry during storage at 4 °C.
Results: Moisture content correlated significantly (p < 0.01) with both skin and flesh hardness of cherry fruit at the two storage temperatures. According to the transverse relaxation curve, relaxation time, as T21 (0.01-10 ms), T22 (10-150 ms), and T23 (150-1000 ms) were ascribed to cell wall protons, cytoplasmic water, and vacuolar water respectively. Contents of cytoplasmic (p < 0.05) and vacuolar water (p < 0.01) changed significantly with storage time. Magnetic resonance imaging results illustrated that water distributes uniformly in fresh tissue. With prolonged storage time, free water content increased gradually, and then internal damage occurred.
Conclusion: Sweet cherry softening closely correlated with moisture loss during low-temperature storage. LF-NMR is a useful technique to investigate moisture migration of fruits and vegetables. © 2017 Society of Chemical Industry.
Keywords: low-field nuclear magnetic resonance; low-temperature storage; moisture migration; softening; sweet cherry.
© 2017 Society of Chemical Industry.