Effects of packaging film, temperature, and storage time on the biochemical properties of dried leaves of Rosmarinus officinalis L. were investigated in a factorial experiment based on a completely randomized design at Gorgan University of Agricultural Sciences and Natu
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Effects of packaging film, temperature, and storage time on the biochemical properties of dried leaves of Rosmarinus officinalis L. were investigated in a factorial experiment based on a completely randomized design at Gorgan University of Agricultural Sciences and Natural Resources during 2017-2018. Plant samples were collected and shade-dried from the newly grown branches of eight-year-old plants in June. Then, the samples were packed in packaging films including control (without coating), polyamide 80, 90, and 120 µ, polyethylene 90 µ and common plastic, before they were stored at 4 ℃ and 25 ℃ for one year. The biochemical compounds of the plant were measured every three-months. Chlorophylls and carotenoids were measured using dimethyl sulfoxide method. Phenols, flavonoids, and antioxidant activity were assayed by Folin-Ciocalteu, aluminum-chloride, and DPPH method. Findings showed that chlorophylls and carotenoids decreased over time; however, 4 ℃ preserved the pigments better than 25 ℃. The highest phenol content (4.5 mg/g) was observed in common plastic after 6 months, and the highest flavonoids (2.87 mg/g) was observed in polyamide 90 µ and polyethylene 90 µ stored for 3 months at 4 ℃. Total phenols and flavonoids in treatments were 1.78 and 3 times higher than the samples without coating stored for 12 months at 25 ℃. The highest antioxidant activity was observed in all packages at the beginning of the experiment, and the antioxidant activity decreased by 30.8% after 12 months storage at 25 ℃ without coating. According to the findings of the study, in order to preserve the quality of dried rosemary leaves, they are recommended to be stored in polyamide 90 and 120 µ and polyethylene 90 µ at 4 ℃ for 3 months, because in these treatments, in addition to the increase in total phenols and flavonoids (1.2-1.3 times compared to the beginning of the experiment), the content of total chlorophylls, carotenoids, and antioxidant activity did not increase highly.
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