| Flos Chrysanthemi, the dried flower heads of Chrysanthemum morifolium Ramat. (Asteraceae), is a commonly used cooling herb in traditional Chinese medicine to treat fever, dizziness, headache, blurred vision, cold, conjunctival congestion, acne, sore throat etc. Caffeoylquinic acids and flavonoids were considered to be the important active components and frequently determined in the quality evaluation of the herb.Many kinds of factors have been found to influence the quality of Flos Chrysanthemi, such as cultivar, environment, soil, fertilizer, collection, processing and storage. However, it is inadequate to evaluate the quality by analyzing only one or a few active compounds. In this paper, simultaneous determination of multiple components was developed, which was used to evaluate the effect of postharvest, collection time and different parts of flower head on the herb's quality. The activities of polyphenol oxidase (PPO) and peroxidase (POD) were investigated to understand the mechanism of postharvest processing. The drying characteristics and dynamic parameters were also measured to optimize the drying process and equipment. The main results are as follows:1. Two HPLC methods were developed to simultaneously determine multiple components in Flos Chrysanthemi for the first time. Validation of the methods proved that these two methods were sensitive, accurate, reliable, repeatable and helpful to the quality evaluation of Flos Chrysanthemi.2. The activities of PPO and POD were measured in the flower heads steam-blanched for different times (0-120 s). The results revealed that the enzyme activities decreased rapidly with increasing steam-blanching time, and steam-blanching for 90 s could inactivate 98% of PPO and 100% of POD.3. The flower heads were sun-dried or oven-dried at different temperatures (60, 80 or 100℃) with or without pretreatment (steam-blanching for 90 s). The results indicated that the contents of caffeoylquinic acids and flavonoids were negatively correlated with drying temperature in those none steam-blanched flower heads, however, positive relationships were obtained in the flower heads with steam-blanching. Steam-blanching combined with drying at 100℃gave a produce of high quality.4. Steam-blanched flower heads were dried at 60,80,100 and 120℃, weighed at an interval of 20 min, and the data were fit to different drying models. The results showed that Midilli model could better fit the drying behaviour of steam-blanched flowers. The effective diffusivities were calculated from the data of the first falling rate stage and ranged from 1.10×10-9 to 6.44×10-9 m2/s, and the activation energy was found to be 1829.5 kJ/kg. Besides, it was found that no significant difference in the pH of the extracts made from the flowers dried at 60-100℃, whereas the pH value of the water extract of those dried at 120℃decreased significantly; electrical conductivity, anti-oxidant activity and caffeoylquinic acid contents were higher in the flowers dried at 100℃and 120℃than at 60℃and 80℃.5. Similar young flower heads were selected and labeled at the early flowing stage, harvested every two days, and nine components were determined by HPLC. It was showed that the contents of caffeoylquinic acids and flavonoids significantly decreased with the flower blooming expressed in unit weight, but they not varied greatly if indicated in per dried flower head.6. The moderately bloomed flower heads were split into several parts:involucre and receptacle, white ligulate flowers, yellow ligulate flowers, bud of ligulate flower and tubular flowers, the contents of nine active components were determined by HPLC. The results showed that the components determined were inhomogeneous in different parts. Involucre and receptacle have a low content of determined compounds; apigenin-7-O-β-glucoside and acacetin-7-O-β-glucoside were highest in white ligulate flowers; 3,5-dicaffeoylquinic acid and 1,5-dicaffeoylquinic acid were highest in yellow ligulate flowers; luteolin-7-O-β-glucoside was highest in ligulate flower buds; chlorogenic acid,4,5-dicaffeoylquinic acid, diosmetin-7-O-β-glucoside and apigenin mainly distributed in tubular flowers.Generally speaking, in this paper, the HPLC method was firstly developed to simultaneously determine the contents of multiple compounds in Flos Chrysanthemi. The activities of deteriorating enzymes and drying characteristics of steam-blanched flower heads were revealed; and the drying parameters were calculated. The effects of drying, collecting time and parts of flower head on the quality of this herb were evaluated. The results laid foundations for the harvesting and processing of the flower heads, and help to stabilize and improve the quality of the herb. |
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