Microstructural indicators of quality-related characteristics of blueberries - An integrated approach

Structure/function relationships associated with blueberry (Vaccinium corymbosum L.) fruit textural quality were studied using an approach which integrated microstructural, compositional and physical data. Microstructural preservation was optimized using standard and novel sample preparation techniques and equipment. A modified light microscopy (LM) technique most clearly illustrated differences among 'Coville', 'Elliot' and 'Burlington' highbush blueberry cultivars, in retention of flesh cell shape, cell wall integrity, degree of contact and amount of space between cells, and could account for storage life differences. Using the LM technique, parenchymal cell wall thickening in the flesh of 'Burlington' blueberries was observed in air stored fruit. The number and arrangement of flesh stone cells, and their cell wall thickness may also contribute to the firming effect observed. When berries lost water during storage, firming was reduced Berry epidermal cells retained their integrity and sub-epidermal cell walls appeared "corrugated". The slight compression used to measure berry firmness caused separation between the sub-epidermal and flesh layers, while uncompressed berries showed no separation. An integrated approach can describe berry quality, aid in trait selection for breeding, and determine optimal storage conditions. Standard berry quality assessment methods may cause microstructural changes which could explain apparent inconsistencies in data. (C) 2001 Academic Press.