Undiagnosed maternal phenylketonuria

Abstract

Recently, rosé ciders and pink apple juices, appeared as a real opportunity to diversify the offer. Juices obtained from red-fleshed apple varieties were used to study the impact of raw material on colour intensity and stability. Juices prevented from oxidation were compared to the corresponding oxidised juices. Juice colours were measured in the CIE Lab space. Polyphenoloxidase activity and pH were measured. Detailed phenolic composition, including anthocyanins, was characterised by reversed phase HPLC coupled to UV-visible and MS detection. Red-fleshed apple varieties revealed great variation regarding red colour intensity of the juice and its enzymatic oxidative degradation. Statistical classification of juices highlighted three behaviours regarding colour and colour degradation; (i) highly coloured juices resistant to colour degradation, (ii) red juices that shifted to orange-yellow colour and (iii) red juices that became pale. No factor could explain alone, nor the classification of juices, nor the oxidation of anthocyanin. Colour degradation must be considered as a multifactorial evolution. Results suggested that PPO activity, pH, concentration of PPO favourite substrates are among the main factors involved, but the amount of the other polyphenols (dihydrochalcones, catechins and procyanindins) must also be taken into account.