Effect of freezing and storage on quality factors in Hamburg and leafy parsley

Two types of parsley — the Hamburg cv Berlińska and leafy type cv Paramount — were frozen and stored at temperatures of −20 and −30 °C for 9 months. One half of the material was blanched before freezing and the other half was non-blanched. In 100 g fresh leaves of Hamburg parsley there were 20.0 g of dry matter, 310mg of vitamin C, 7.5mg of β-carotene, 203mg of chlorophyll, 30.8 mg NNO3 and 0.078 mg NNO2. For the leafy type the corresponding values were 17.3 g, 257 mg, 9.4mg, 68.5mg, and 0.077mg. The material blanched before freezing showed significant losses in the contents of vitamin C (47–51%), nitrates (22–33%), and nitrites (43–55%) and distinctly smaller ones but also significant in the case of dry matter. During freezing and storage of frozen products there were losses in vitamin C, β-carotene, and chlorophyll while the levels of nitrates and nitrites were variable. Particularly great losses of vitamin C and β-carotene were observed in the non-blanched frozen leaves stored at −20 °C. After 9 monthsʹ storage, frozen products preserved 10–44% of vitamin C, 37–91% of β-carotene, 78–95% of chlorophyll, and 78–153% of nitrates. Of the types of parsley analyzed the Hamburg type was a better raw material for freezing because of a significantly higher content of vitamin C and chlorophyll and significantly less nitrates in frozen products. When the storage temperature was −30 °C, the blanching of leaves was not necessary, although it helped their pressing into cubes.