Bacterial Disinfection Using Ozone Gas to Extent Spinach’s Shelf Life: The Effect of Dosage, Duration, and Spraying Frequency

Spinach (Amaranthus tricolor) is one type of leafy vegetable famous as a nutrition source in Indonesia. However, it has short shelf life due to bacterial activity, which requires an alternative preservation solution besides drying. Ozone can be used as a disinfectant that is not harmful to humans and has been applied in food and agricultural product preservation. Ozone gas spraying reduces bacterial growth so that quality degradation due to decay can be slowed. In this research, spinach is preserved by spraying ozone gas to the extent of its shelf life. Spinach is ozonated with ozone gas at various dosages of 30.72 mg/hr, 48.60 mg/hr, and 80.16 mg/hr, with the spraying frequency of once, twice, and 3 times for 15 minutes. Ozone gas spraying duration is also variated: 2 minutes, 3 minutes, and 6 minutes. Then, the sample is stored for 7 days to see the change of its characteristic. The best quality during storage is shown by spinach treated with ozonation at a dosage of 48.60 mg/hr; 6 minutes; and the frequency of 3 times. In addition to variations in duration, dosage, and frequency, the same ozone exposure with different combination of duration-frequency and duration-dosage were also observed to evaluate the optimum ozone treatment for preserving spinach, and it was found that longest duration-least frequency and moderate duration-moderate dosage are preferred in maintaining the quality of spinach during storage.