Determination of some physicochemical and microbiological properties of rosehi̇p marmalades produced by traditional methods in Çorum region

This study aimed to investigate the physicochemical and microbiological properties of rosehip marmalade samples produced by traditional methods in Çorum. Additionally, industrially produced samples were evaluated and compared in terms of their product characteristics. A total of 88 marmalade samples were analyzed, 70 of which were produced traditionally in 2021 (n=40) and 2022 (n=30), while 18 samples were produced industrially. Water-soluble dry matter, pH, total acidity, ash, total phenolic substance, total flavonoid, ascorbic acid, total carotenoid, antioxidant capacity, HMF, sugar, organic acid and color analyses were performed in all samples. In addition, the samples were evaluated microbiologically in terms of total aerobic mesophilic bacteria, total yeast-mold, coliform bacteria and osmophilic yeast counts. The water-soluble dry matter contents of the traditionally produced marmalade samples (average 34,8±5,3) were found to be below the legally specified limit. Strong positive correlations were observed between the bioactive components and antioxidant capacity, indicating that samples with higher levels of total phenolic substances, total flavonoids, and total carotenoids exhibited greater antioxidant capacities. It was determined that the production technique had an impact on the ascorbic acid and HMF levels, with marmalade samples produced traditionally having lower ascorbic acid and higher HMF contents compared to commercial samples. The organic acid, sugar, and color contents of the marmalade samples exhibited a relatively wide range. The microbial analysis results of commercial samples were found to be below the detectable level, while the samples produced traditionally were found to be susceptible to microbial growth, and 8 out of 70 traditional samples were found to contain yeast-mold above the limits. Within the scope of the study, changes in physicochemical, microbiological and sensory properties of rosehip marmalade samples stored in refrigerated conditions and at room temperature for 9 months were also discussed. While there were no significant changes in parameters such as organic acid, ash, and total carotenoids during the storage of marmalade samples produced by the traditional method, there were losses up to 10% in the total phenolics and total flavonoid contents of the samples depending on the storage temperature. The loss of ascorbic acid was much higher, at the level of 28% in samples stored in refrigerator conditions and 48% in samples stored at room temperature. There was no increase in the HMF content of the samples during storage. The change in color values remained at a much more limited level in samples kept under refrigerator conditions. Similarly, marmalade samples kept in refrigerator conditions got higher scores in sensory evaluation. No microbial growth was detected in the microbiological analyses performed during storage.