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QUAFETY project: effects of hot water treatment on fresh-cut produce

The Reserach Group, coordinated by Maria Grzegorzewska, at Research Institute of Horticulture Skierniewice (Poland), partner in Quafety European Project, has investigated the effect of hot water treatment on shelf-life of rocket, Chinese cabbage, and muskmelon.

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 38C to 57C 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 - 20C.

It was found, that after short immersion in water at above 53C, 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 53-55C 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 18C 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 40C for 10 minutes and 53C for 3 seconds were packed into plastic bags (20 x 20 cm) with perforation (10 holes with 0,04cm).

The intact melons were washed, dried and peeled. Then, the fruits were cut into 14 - 16 pieces, treated with water at 53C 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 18C 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 18C for 4 days contained highest amounts of soluble polyphenols regardless the postharvest treatment, while cabbage stored at 1C for 7 days had the highest antioxidant activity. Treatment with water at 40C 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 55C for 3 seconds and stored at 18C for 2 days or stored at 5C 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 5C. Storage of cut muskmelon, especially at 18C, regardless of hot water treatment, affected the decrease of nitrates content.

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Publication date: 5/29/2014


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