The goal of the study was to assess the content of vitamin C in wild rose (dog rose – Rosa canina L.) in relation to the storage method and storage duration. The material for the study was collected from three sites in Poland. The first set of samples was collected in Chełmno and the city of Koło (in the region of Wielkopolska). The second set of samples was obtained in Busko Zdrój. The third set of samples was collected near the city of Mielec. 12 samples of fresh rosehips were collected from each of the areas listed above (1 sample = 1 bush). In total, 36 samples were gathered, weighing approximately between 500 g and 600 g. The material for laboratory analysis was divided into fresh fruit, fruit intended for freezing, and fruit intended for drying. Vitamin C content was determined by the use of the Tillmans method. A part of the rosehips was frozen in a freezer at a temperature of about –18°C, and stored for subsequent months. Another batch of rosehips was subjected to drying. Next, the analysis was performed on freshly preserved samples. The dried rosehips were divided into two groups: Group 1 – dried rosehips, stored at room temperature (about 21°C) in a dark room; Group 2 – dried rosehips, stored at a temperature of about 3°C in a refrigerator. Subsequent measurements were made two, three, five and nine months after freezing or drying. As a result of conducted analyses, it was determined that the highest average content of vitamin C in fresh dog rose fruit was found in rosehips from the vicinity of Mielec, followed by those collected from Wielkopolska. The lowest content was found in the rosehips collected in Busko−Zdrój. On average, after preservation, rosehips lost approximately 25% of their vitamin C content (23% loss after drying, and 25% loss after freezing). During storage of rosehips in different conditions, it was found that the content of vitamin C decreased at the slowest rate in frozen fruits, while in dried rosehips this process was much faster. It was also observed that dried rosehips stored at room temperature, after 5 months of storage, lost vitamin C faster than the dried rosehips that were stored in the refrigerator. The test results clearly show that freezing and storing frozen rosehips is the best method of rosehip stabilization as far as the preservation of the highest content of ascorbic acid is concerned. The loss in the amount of vitamin C after a prolonged storage period amounted to about 10% in relation to the amount of the vitamin measured immediately after freezing. It was also noted that after about 5 months of storage, the content of vitamin C in dried rosehips decreased rapidly, and after 9 months, the loss was about 45% for dried rosehips stored in the refrigerator, and about 80% for dried rosehips stored at room temperature.

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