Metabolic profiling of blueberries (Vaccinium Spp.) to quantitatively and qualitatively assess bruise damage and fruit deterioration

Bruise damage is a type of subcutaneous tissue failure in fresh produce and may seriously affect postharvest quality, limiting machine harvesting of blueberries for fresh resale. In the present study, an empirical model of finite elements was built to predict bruise susceptibility and position in blueberries with varying mechanical force. Fruit quality tests revealed that blueberries were sensitive to mechanical damage in predicted positions, which appeared as softening, cell membrane damage, decay weight and titratable acidity losses in whole fruit. Liquid chromatography mass spectrometry (LC–MS) revealed that blueberries had at least 87 distinct and annotated metabolites related to bruise damage. Lipids and lipid-like metabolites were highly responsive factors for damage development. 6-{3,5-Dihydroxy-2-[3-(4-hydroxy-3-methoxyphenyl)-2-oxopropanoyl]phenoxy}-3,4,5-trihydroxyoxane-2-carboxylic acid and 2,6-dimethoxy-1,4-benzoquinone (DMBQ) showed good correlation with damage severity, showing potential as mechanical damage indicators. Moreover, the LC–MS results confirmed bruise damage reduced the content of DMBQ in blueberries, which is one of effective mediators stimulate efficiency of biodegradation processes of fungi. This study quantitatively and qualitatively assessed bruise damage and identified potential damage-responsive factors and indicators of blueberries under excessive mechanical force.