Characterisation of phenolic compounds and polysaccharides in strawberry: Cultivar and harvest effects and their correlation with nectar colour stability.

Low colour stability in strawberry nectar during storage led to the study of polyphenols and polysaccharides in fruit and their potential role in colour after processing in relation with cultivar, ripening stage and harvest time. Cultivar had a significant effect on both polyphenols and cell wall polysaccharides. Anthocyanins and proanthocyanidins (PACs), including procyanidin and propelargonidin, were the main polyphenols in strawberry. Ripening and late harvest increased anthocyanin contents and reduced PACs contents whereas changes in other polyphenols were minor. Cell walls were mainly composed of cellulose, highly methylated pectins rich in arabinan and galactan side chains, and xyloglucan. Ripening and late harvest increased the loss of pectin side chains, yet these effects were cultivar-dependent. Overripe samples from late harvest exhibited greater colour stability after nectar production. Strawberries with a high content in anthocyanins, low content of PACs, and with pectins rich in galactose, were correlated with nectars of higher colour stability.