Submitted to: Journal of Food Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2004
Publication Date: 6/1/2004
Citation: Link, S.O., Drake, S.R., Thiede, M.E. 2004. The prediction of firmness from mass loss and shrinkage in apples. Journal of Food Quality. 27:13-26.
Interpretive Summary: Apples lose firmness and thus quality during storage. It is difficult to track firmness in storage because the standard method is destructive and requires entry into storage rooms. A technique that can predict firmness reliably without entering storage rooms would be helpful for determining when to pack fruit for best quality. Prediction of firmness from mass loss and shrinkage was determined in this study. I was determined that the relationship between firmness and mass loss, or shrinkage was dependent on apple cultivar. Firmness was linearly related to mass loss and shrinkage in 'Delicious' apples, but not 'Fuji' apples. It is possible to predict firmness of 'Delicious' apples by mass loss or shrinkage and never enter the storage area. Use of mass loss to predict firmness has the advanage that the entire apple is measured while shrinkage was measured at only two points.
Technical Abstract: The prediction of firmness from mass loss and shrinkage was investigated in apples (Malus x domestica Borkh.) under regular atmosphere (RA) storage conditions. The 'Delicious' variety was compared with the 'Fuji' variety. Apples were repeatedly weighed to determine mass loss. Shrinkage was measured with a strain gauge sensor. 'Delicious' apples lost firmness (73 to 58 N) while 'Fuji' apples maintained firmness at 69 N over 57 days in storage. Apples lost mass at a constant rate with 'Delicious' losing slower (0.6% per month) than 'Fuji' (1.1% per month). The 'Delicious' apple shrank less (0.28 mm) than the 'Fuji' (0.70 mm) over 57 days. The relationship between firmness and mass loss, or shrinkage was dependent on apple variety. Firmness was significantly and linearly related to mass loss and to shrinkage in 'Delicious' apples. It is possible to predict firmness of 'Delicious' apples under RA storage conditions by tracking mass loss or shrinkage. Further work is needed to confirm these results and to determine the effect of other factors on the relationship between firmness and mass loss, or shrinkage such as variety, fruit size, initial water content, wax, plus growth, harvest, and storage conditions. Use of mass loss to predict firmness has the advantage because the entire fruit is measured while shrinkage is measured at only two points.