Analysis of protein expression and the production of aroma compounds during strawberry ripening

Strawberry is a plant species widely grown in the temperate regions of the world, and it is a commercially important non-climacteric soft fruit. To gain insight into the biochemical determinants associated with fruit ripening, we analysed protein expression and volatile aroma compounds during fruit ripening. In addition we assayed lipoxygenase (LOX) and hydroperoxide lyase (HPL) activities during strawberry ripening. These enzymes are involved in the biogenesis of the major constituents of "green odour". Two-dimensional maps revealed that a relevant number of proteins were differentially expressed in the green (180 polypeptides) and the pink (227 polypeptides) maturation stages compared to the red stage. LOX activity was higher in pink than in green fruit, then decreased in mature fruit. HPL activity reached a maximum level at the early maturation stage and decreased slowly during ripening. The occurrence of hexanal, trans-2-hexenal and ethyl hexanoate and their relationship with LOX and HPL are discussed.