This increase
may determine a reduction in water activity, causing unfavourable
conditions for pathogens to establish infection on citrus peel
Moreover,
it has been reported that phenolics and anthocyanins increase
rapidly in the skin of grape berries one week after the start of soluble
sugar accumulation (Pirie and Mullins, 1980) depending on
the availability of phenylalanine, which is synthesized from sugars
through the shikimate pathway .
Thus,
sugar accumulation might provide the substrate needed for the
synthesis of various secondary metabolites including phytoalexins