3.6 Impact of high CO2 on sugar accumulation and weight loss reduction
The marked accumulation of major soluble sugars in CO2-treated fruit suggests that is has better osmotic adjustment. This has a significant influence on weight loss reduction in fruit. Detailed data relating to weight loss are presented in Figure 6. During LT storage, average weight loss throughout the early stage of storage at 0 ºC was significantly lower in CO2-treated strawberries in comparison to fruit stored in air. After 7 days of storage at 0 ºC, the percent of weight loss was also more accentuated in fruit stored in air than in the fruit pre-treated with CO2 for 2 days. In this case, a reduction in weight loss of 47-50% was recorded due to high CO2 treatment. Weight loss did not exceed 1% at any stage during LT storage (Figure 8). When fruit were transferred to 20 ºC for 1 day, significantly less weight was lost in fruit previously stored at low temperature than those directly kept at 20 ºC. However, weight loss was not significantly different between fruit with or without CO2. When SL was prolonged for two days, water loss was significantly higher in fruit stored in air than in CO2-treated fruit. Average weight loss in SL+LTA was 1.0%, compared to 0.8% in SL+LTC and 1.5% in fruit stored directly at 20 ºC. CO2-treated strawberries showed the lowest weight losses after 2 days at 20 ºC. Present results show that pre-treatment with 17% CO2 for 2 days limited water loss during SL.
We speculate that increased soluble carbohydrate concentration is engendered by a lower consumption of hexoses. This may be due in part to its low availability as present results evidenced that reduced sucrose breakdown by FvSS1, FvVINV1 and FvVINV2 avoiding water loss.