Controlled—modified atmosphere storage vegetables

Methanethiol has a very low flavor threshold value (0.02 ppb in water 15), and possesses a strong, offensive, fecal-like odor (18). It also is readily converted to very unpleasant oxidized sulfurous off-flavor compounds with low detection thresholds, such as dimethyl disulfide and dimethyl trisulfide (18,25). Thus, suppression or modulation of methanethiol formation in cruciferous vegetables would le to a reduction of off-flavors associated with methanethiol-related compounds, and enhance the utility of controlled and modified atmosphere storage technologies for these vegetables. 

In addition to the traditional canning, freezing, pickling and dehydration processes, several new processing techniques have surfaced in recent years. Irradiation with gamma rays, storage with controlled and modified atmospheric environment, reverse osmosis and ultrafiltration will be discussed in subsequent chapters. The emphasis will be on chemistry of quality improvement of the processed fruit and vegetable products. 

Literature is scarce on the effects of controlled atmosphere (CA) and modified atmosphere (MA) storage on carotenoid content and colonr retention in yellow and red vegetables. Sozzi et al. (1999), reported a lower content in total carotenoids and lycopene in tomatoes, which had been stored in 3% O2 or 20% CO2 than after storage in air (control). No differences were fonnd after storage in low O2 and high CO2. When the samples were transferred to air, the total carotenoid and lycopene contents were lower in the tomatoes, which were subjected to different storage treatments from those stored in air all the time. 

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