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

Structure/function relationships associated with blueberry (Vaccinium corym bosum L.) fruit textural quality were studied using an approach which integ rated microstructural, compositional and physical data. Microstructural pre servation was optimized using standard and novel sample preparation techniq ues 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 fo r storage life differences. Using the LM technique, parenchymal cell wall t hickening in the flesh of 'Burlington' blueberries was observed in air stor ed fruit. The number and arrangement of flesh stone cells, and their cell w all thickness may also contribute to the firming effect observed. When berr ies lost water during storage, firming was reduced Berry epidermal cells re tained their integrity and sub-epidermal cell walls appeared "corrugated". The slight compression used to measure berry firmness caused separation bet ween the sub-epidermal and flesh layers, while uncompressed berries showed no separation. An integrated approach can describe berry quality, aid in trait selection f or breeding, and determine optimal storage conditions. Standard berry quali ty assessment methods may cause microstructural changes which could explain apparent inconsistencies in data. (C) 2001 Academic Press.