Strawberry Bruising and Energy Dissipation

A strong correlation was obtained between bruise volume and energy absorbed for impact and quasi‐static compression of Redlands Earlisweet and Redlands Crimson strawberries. The Redlands Earlisweet variety of strawbem'es was significantly more resistant to bruising than Redlands Crimson. Strawberry tissues was more easily bruised by slow compression than by impact for both varieties. For the same amount of energy, bruise volumes were aproximately 40% higher under slow compression. A simple model is formulated to exptain the behavior of strawberries under compression Strawberry tissue is likened to an orderly arrangement of liquid file & spherical cells bounded by viscoelastic membranes with air filled interstitials. It is postulated that compression results in change of cell shape leading to cell wall fracture, i.e., cell bursting, in regions of high shearing stress. Distortion and bursting of cells explains the energy dissipative nature of bruising. The work shows that energy absorbed is a good predictor of bruising and is thus a useful parameter in evaluating handling and packaging systems for strawberries.