Influence of different pectins, process and storage conditions on anthocyanin and colour retention in strawberry jams and spreads

Strawberry jams and spreads were prepared under reduced pressure at various temperatures (70, 75 and 90 °C, respectively) using amidated, high and low esterified commercial pectins. For their full characterisation, dry matter, ash contents and amounts of selected metal ions were determined. Gel strength measurements were performed, and the products were stored in the dark (+20 ± 2 °C and +4 ± 2 °C, respectively) and under light exposure (+20 ± 2 °C/4500 lux) over a period of 24 weeks. Amounts of monomeric and polymeric anthocyanins were monitored spectrophotometrically, individual anthocyanins were assessed by HPLC-DAD-MSn, and colour measurements were carried out applying the CIE L*a*b* system.Pigments and colour were best retained immediately after processing, when jams were cooked at 70 °C under reduced pressure. Anthocyanin storage stability was generally higher in the jams than in the spreads strongly depending on pectin type and water activity. Storing the products at +4 °C in the dark was indispensable for sufficient colour and pigment retention, while illumination resulted in rapid discolouration.

► Strawberry jam and spread preparation on pilot-plant scale with different pectins. ► Anthocyanin storage stability was markedly higher in jams than in spreads. ► The pectin type strongly affected anthocyanin storage stability in jams and spreads. ► Best colour and pigment retention was achieved by cold storage of the products. ► Illumination proved to markedly decrease colour and pigment stability.