The effect of high hydrostatic pressure on the anthocyanins of raspberry (Rubus idaeus)

The colour stability of fruit puree made from raspberries (Rubus idaeus), which were subjected to high hydrostatic pressure, was studied by measuring the anthocyanin content. High hydrostatic pressure is an alternative method of food preservation to heat treatment. In this study, we assess the impact of high pressure on the colour molecules in raspberries. Fruit samples were pressured under 200, 400, 600 and 800 MPa for 15 min at a temperature controlled between 18 and 22°C. After application of pressure, the high pressure treated samples were kept at refrigerator temperature (4°C), room temperature (20°C) and at 30°C. The anthocyanin content of the raspberries was analysed after 1, 2, 4, 7 and 9 days of storage by HPLC-UV using an isocratic elution system. Two pigments were identified and quantified: cyanidin-3-glucoside and cyanidin-3-sophoroside. The highest stability of the anthocyanins was found when raspberries were pressured under 200 and 800 MPa and stored at 4°C. © 2004 Elsevier Ltd. All rights reserved

The effects of high hydrostatic pressure on β-glucosidase, peroxidase and polyphenoloxidase in red raspberry (Rubus idaeus) and strawberry (Fragaria x ananassa)

The effects of high hydrostatic pressure on 3 important enzymes involved in flavour and colour bioformation, namely β-glucosidase, peroxidase and polyphenoloxidase, in red raspberry (Rubus idaeus) and strawberry (Fragaria×ananassa) were studied. Fruit samples were pressurised under 400, 600 and 800 MPa for 5, 10 and 15 min at a temperature controlled between 18 and 22°C. After application of pressure, the enzymatic activities (A) were measured and compared to the initial activities of the samples (A0). The effect of high pressure is presented as a function of the ratio A/A 0 over pressurising time. The inactivation of the enzymes is linked to the stability of anthocyanins in both fruits. © 2004 Elsevier Ltd. All rights reserved