426 Novel food packagi that 40-50kPa O2 accelerated ripening of tomatoes, with 60-100kPa stimulating synthesis of lycopene in rin varieties. 40-80kPa O2 improved the colour of endocarp and juice of orange cultivars, increasing the deepest of orange colour. However, an undesirable change from yellow to orange has been observed in grapefruit. An increase in the red colour of flesh and juice of blood-orange Sanguine'cv has been related to anthocyanin synthesis Superatmospheric O2 was particularly effective in inhibiting browning of different fresh processed vegetables including mixed salads and chicory endive (acxsens et al, 2001, Allende et al., 2002). However, "Bartlett pear slices kept in 40, 60 or 80kPa O2 exhibited similar severity of cut surface browning during storage at 10C(Gorny et al., 2002). 20.5.2 High carbon dioxide effects Tolerance to high CO2 is commonly reduced in fruit and vegetables. As example, levels of 3-5kPa induced superficial scald and abnormal flavour in citrus during cold storage(Artes, 1995; Kader, 1990). For this reason, the use of COz for keeping colour in plant materials must be particularly adapted for each Exposure of mango fruits to 50kPa CO2 at 40-44C for 160 minutes used as a uarantine treatment affected colour during cold storage. After 20 days at 10oC control fruits showed a higher decrease in hue than those heated under co enriched CA. Decrease in hue was a good estimator of the green to yellow colour turn. Yellowing increased in the absence of CO2 and chroma(colour intensity) decreased(Ortega-Zaleta and Yahia, 2000) MAP stored peaches for 21 days at 2C, with equilibrium CO2 level about 20kPa, showed a residual effect of high CO2 during the subsequent three days at 20oC. Colour development was slow and L* and chroma ground values were maintained as at harvest(Fernandez-Trujillo et al, 1998). However, very high CO2 levels(73kPa in MAP) destabilised cyanidin derivatives in the skin of Starkimson' apples(Remon et al., 2000) Despite the benefits of CO2 enriched atmospheres in controlling postharvest decay, anthocyanin concentration is affected and more particularly in the internal tissues During storage of strawberries in air plus 10 or 20kPa CO2, skin chroma increased with time and was not as affected by gas composition as flesh colour which turned pale. The hue of berries held in air was lower than that in CA and chroma under 10kPa COz was slightly higher than under 20kPa CO (Holcroft and Kader, 1999a) In contrast to the effect observed in strawberries co, did not affect anthocyanin in pomegranate fruit. Juice red colour increased in intensity during postharvest storage(8 weeks, 5C)when 5kPa CO2 was combined with 5kPa O2 while air-stored fruits showed a slight pale red (low a" value)colour(Artes et al., 1996). Chroma of the skin was better maintained when fruits were stored in air plus 10kPa CO2 while L' of the internal integuments decreased with time due to browning Integuments were darker after six weeks at 10C and 20kPathat 40–50kPa O2 accelerated ripening of tomatoes, with 60–100kPa stimulating synthesis of lycopene in rin varieties. 40–80kPa O2 improved the colour of endocarp and juice of orange cultivars, increasing the deepest of orange colour. However, an undesirable change from yellow to orange has been observed in grapefruit. An increase in the red colour of flesh and juice of blood-orange ‘Sanguine’ cv has been related to anthocyanin synthesis. Superatmospheric O2 was particularly effective in inhibiting browning of different fresh processed vegetables including mixed salads and chicory endive (Jacxsens et al., 2001, Allende et al., 2002). However, ‘Bartlett’ pear slices kept in 40, 60 or 80kPa O2 exhibited similar severity of cut surface browning during storage at 10ºC (Gorny et al., 2002). 20.5.2 High carbon dioxide effects Tolerance to high CO2 is commonly reduced in fruit and vegetables. As an example, levels of 3–5kPa induced superficial scald and abnormal flavour in citrus during cold storage (Arte´s, 1995; Kader, 1990). For this reason, the use of CO2 for keeping colour in plant materials must be particularly adapted for each species. Exposure of mango fruits to 50kPa CO2 at 40–44ºC for 160 minutes used as a quarantine treatment affected colour during cold storage. After 20 days at 10ºC control fruits showed a higher decrease in hue than those heated under CO2 enriched CA. Decrease in hue was a good estimator of the green to yellow colour turn. Yellowing increased in the absence of CO2 and chroma (colour intensity) decreased (Ortega-Zaleta and Yahia, 2000). MAP stored peaches for 21 days at 2ºC, with equilibrium CO2 level about 20kPa, showed a residual effect of high CO2 during the subsequent three days at 20ºC. Colour development was slow and L* and chroma ground values were maintained as at harvest (Ferna´ndez-Trujillo et al., 1998). However, very high CO2 levels (73kPa in MAP) destabilised cyanidin derivatives in the skin of ‘Starkimson’ apples (Remo´n et al., 2000). Despite the benefits of CO2 enriched atmospheres in controlling postharvest decay, anthocyanin concentration is affected and more particularly in the internal tissues. During storage of strawberries in air plus 10 or 20kPa CO2, skin chroma increased with time and was not as affected by gas composition as flesh colour which turned pale. The hue of berries held in air was lower than that in CA and chroma under 10kPa CO2 was slightly higher than under 20kPa CO2 (Holcroft and Kader, 1999a). In contrast to the effect observed in strawberries, CO2 did not affect anthocyanin in pomegranate fruit. Juice red colour increased in intensity during postharvest storage (8 weeks, 5ºC) when 5kPa CO2 was combined with 5kPa O2 while air-stored fruits showed a slight pale red (low a* value) colour (Arte´s et al., 1996). Chroma of the skin was better maintained when fruits were stored in air plus 10kPa CO2 while L* of the internal integuments decreased with time due to browning. Integuments were darker after six weeks at 10ºC and 20kPa 426 Novel food packaging techniques