Investigation of Vibration Technique to Control Physical Properties of Yam Tubers (Dioscorea rotundata Poir.) During Storage

Abstract

Yam  tubers  loss  weight  during  storage  and  prolonged storage  can  reduce  tuber  quality  and  quantity. This study  investigated the application  of  vibration technique  for  the  control  of  physical  properties  of  yam tubers during storage.  Measurements were conducted on  the  physical properties  of  the  tubers:  weight loss,  shrinkage  of  the  middle diameter,  shrinkage  of the  length,  top  and  bottom  diameter,  on  108  tubers treated  and  32  tubers  untreated  (control).  The  factors of  the experimental design  were three levels of vibration  frequencies,  i.e.  low  (1  –  5  Hz),  medium  (60 –  100  Hz)  and  high  (150  –  200  Hz),  amplitudes  of  low (5  mm),  medium  (10  mm),  and  high  (20  mm),  and durations  of  low  (5  minutes),  medium  (10  minutes) and  high  (15  minutes).  Tuber  weights  were  classified as  small  (0.1  –  2.9  kg)  and  large  (3.0  –  5.0  kg).  The tubers were stored for ten weeks after  vibration,  and their physical  properties  were measured  every week during  the storage period. Our study demonstrated that  as  the  frequency,  amplitude,  and  duration  of vibration increase, the physical properties of yam tubers  decrease  significantly  in  both  tuber  classes. The  study  shows that  mechanical vibration can slow down  the changes of  the physical properties of  yam tuber during  storage.