Mechanical properties of mulberry fruit under compression and nuclear magnetic resonance tests
Junming Hou, Weixue Hu, Liang Zhang, Zhaotan REN, Qijie Sun, Wei Wang
Abstract
Abstract During the mechanized production and processing of mulberry, the fresh fruit can experience serious mechanical damage. In this study, compression tests were conducted to investigate the effect of different parameters on the compression damage to mulberry. The results showed that the extent of compression damage was mainly influenced by the loading displacement rate applied during compression; the damage was increased with increasing loading displacement. At an initial moisture content of 86.76%, the indentation area ratio was increased from 0.0725 to 0.2756 when the loading displacement increased from 3.0 to 6.0 mm. Nuclear magnetic resonance (NMR) spectroscopy was used to observe the changes in the internal moisture content of mulberry before and after compression under different loading rates. When the loading displacement increased from 3.0 to 6.0 mm, the loss of free and bound water in mulberry also increased. Further, with the increase in extrusion, the damage to the mulberry fruit increases significantly. It is proved that the method of image recognition and NMR is feasible to verify the damage to the mulberry fruit. Practical Applications Because mulberry has a soft texture, it can be easily damaged by extrusion during mechanized production and processing. In this study, a relationship between various factors of compression process and mulberry extrusion damage was established using compression test results. This can be used as a reference for reducing mulberry extrusion damage in the process of mechanized production and processing. Because the extent of damage to mulberry is difficult to identify, this study provides a feasible method to identify the crushing damage to mulberry.