QUAFETY project: effects of hot water treatment on fresh-cut produce
Rocket
Rocket salad (Eruca sativa M.) cv. ‘Siewna’ and wild rocket (Diplotaxis tenuifolia L) cv. ‘Gourmet F1’ were tested. Salad rocket was cultivated at Experimental Field of Research Institute of Horticulture in Skierniewice, but wild rocket was bought from vegetable producer. The plants immediately after harvest were sorted and trimmed, and then treated with hot water.
The temperature of hot water ranged from 38°C to 57°C and the time duration of treatment varied from 20 minutes to 3 seconds. The parameters of hot water were evaluated in subsequent tests on the basis of previous results. After hot water treatment, the leaves were dried, cooled to equal temperature, packed into polystyrene foam trays and stored at room temperature 18 - 20°C.
It was found, that after short immersion in water at above 53°C, the leaves maintained the green colour longer than untreated leaves. The rocket salad appeared to be more susceptible to the treatments resulting in the tissue decay. The decay rate depended on the hot water temperature and the time of treatment. The wild rocket was more resistant against tissue decay. After 4 days at room temperature, leaves treated in water at 53-55°C maintained significantly a higher marketable value compared to those treated in lower temperature or not treated.
Chinese cabbage and muskmelon
The effects of treatment with hot-water on quality of fresh-cut Chinese cabbage (Brassica rapa L. var. pekinensis) and muskmelon (Cucumismelo L.) during storage at 1, 5 and 18°C were investigated.
The leaves of Chinese cabbage were cut into strips of width 1,0 – 1, 5 cm. The cabbage strips washed in tap water (control or untreated) or after treatment with hot water at 40°C for 10 minutes and 53°C for 3 seconds were packed into plastic bags (20 x 20 cm) with perforation (10 holes with ø 0,04cm).
The intact melons were washed, dried and peeled. Then, the fruits were cut into 14 - 16 pieces, treated with water at 53°C for 3 seconds and packed into polystyrene foam trays placed in crate lined with PE film. Vegetables were analysed for content of dry matter, vitamin C, total sugars, soluble polyphenols and nitrates. The loss of dry matter during storage at 1, 5 and 18°C in untreated and hot water-treated cabbage was measured. Untreated cabbage maintained the highest content of vitamin C and was characterized by a higher antioxidant activity.
Cabbage stored at 18°C for 4 days contained highest amounts of soluble polyphenols regardless the postharvest treatment, while cabbage stored at 1°C for 7 days had the highest antioxidant activity. Treatment with water at 40°C resulted more effective in preserving cabbage quality.
As regards muskmelon, there was an increase of dry matter content in fresh-cut fruits treated with water at 55°C for 3 seconds and stored at 18°C for 2 days or stored at 5°C for 5 days. Level of vitamin C and total sugars were affected by neither hot water treatment or storage temperature. Soluble polyphenols content was significantly affected by hot water treatment and storage at 5°C. Storage of cut muskmelon, especially at 18°C, regardless of hot water treatment, affected the decrease of nitrates content.
For further info contact:
maria.grzegorzewska@inhort.pl