A New Processing Technique for Drying Fresh Flowers of Species in Camellia Sect.Theopsis

Ni Sui*  Ying Zhen  Han Qin  Wu Fan

Faculty of Life Science and Biotechnology, Ningbo University, Ningbo 315211, PR China

Plants of Theaceae including tea and camellias are very common and valuable in south China. In China, people started to plant, produce and drink tea several thousand years ago. Tea and camellias are the homology plants in genus of Camellia, so camellias probably have the same components in leaves as tea. Some products made of camellias in Taiwan and Guangxi of China are used as a kind of food by local people.

Sect.Theopsis belongs to Theaceae and Camellia. They have tiny, dense and fragrant flowers. Most of them are evergreen bushes or small trees. At present, research into Sect.Theopsis mostly focuses on features of their growth requirements and classification, but few have been on their chemical components in petals and leaves. In this paper, a new technique for drying fresh flowers has been successfully developed for C.parvicuspidata, C.handelii, C.tsofui, C.buxifolia, C.fraterna, C.cuspidata var.grandifora, which may provide a method of storage for long periods, which is very useful in developing some new camellia products in fields of medicine, health and food.

1 Material and Method

1.1Samples treatment

Flowers of C.parvicuspidata, C.handelii, C.tsofui, C.buxifolia C.fraterna, C.cuspidata var.grandifora were collected inMarch to April 2012, in Jinhua International Camellia Species Garden, Zhejiang Province, China. Prior to beginning the experiment, they were cleaned using pure water and dried at room temperature of 15℃ for one day.

1.2 Instruments

Analytical balance: METTLER TOLEDO AM104; Air dry oven: Jiacheng DHG-9045.; Microwave:  GalanzP70D20P-TD(WO); Oven: Midea MT10AH-AA

1.3 Reagent

Pure water

1.4 Method

1.4.1Pretreatment

Screening out half-opening flower samples by hand.

1.4.2 Blanching

Blanching is a most important process in processing tea, which influences the quality of tea.Sect. Theopsis belong to Theaceae, just like tea. So blanching treatment should be a key step when drying.

1.4.2.1Microwave blanching

Weigh the fresh flower samples. Set the microwave power at 800w, 600w, 500w, 400w and blanching time at 20s, 40s, 60s, 80s, 100s, 120s. Six kinds of fresh flowers were treated at one time.

1.4.2.2 Thermal blanching

Weigh the fresh flowers samples. Set the temperature control at 80℃, 100℃, 120℃, 140℃ and blanching time at 30s, 60s, 90s, 120s, 150s, 180s. Six kinds of fresh flowers were treated at one time.

1.4.3 Drying

The better quality flowers were chosen for next step before drying.

1.4.3.1 Dry by microwave

Choose the better quality samples in 1.4.1 and dry them under microwave at 100w. A sample of them was observed and recorded every 10 min. All of them were dried until water content was less 10%.

1.4.3.2 Thermal drying

Choose the better samples of good appearance in 1.4.1 and dry them under 60℃. A sample of them was observed and recorded every 30 min. All of them were dried until water content was less 10%.

2 Results and analysis

2.1 Blanching results

2.1.1 Blanching by Microwave

Results in Table 1 showed that there was very significant drying effect from microwave treatment. Flowers in six samples turned from half-opening (HO) to full-opening (FO) when microwave power at 800w and blanching time lasting for 20s. and the color of treated flowers has the best appearance and looked like fresh flowers. The color of flowers changed from white (W) to pale yellow (PY) when blanching time lasted for 40s. When blanching time lasted for 80s, the color of flowers was changed to yellow (Y), with average appearances. Flowers were wrinkled up at 100s treatment. At last, the color of treated flowers was changed from pale yellow to deep yellow (DY) in 120s and had the worst appearance. The samples’ color was changed to PY with the best appearance when power at 600w, and blanching time lasted for 60s. At treatment of 80s, flowers changed from HO to FO, and colors were not changed further. At 120s the samples were shrinking (S) and had the worst appearance. Six samples’ appearances were not changed further when microwave power was at 500w or 400w, in which shapes of flowers are still in FO. In 80s, color turned to PY, with the better appearances. But the high water contents resulted in difficult drying. On basis of color variations of six samples in various treatments, we found that the best combinations of treatments is microwave blanching at 600w and lasting for 80s, which produces the best quality of flower appearance.

Table1 Effects of microwave treatment at various times

Shape：full open(FO);half open (HO); shrinking(S); color：deep yellow(DY) ;yellow(Y) ;pale yellow(PY) ;white(W)

2.1.2 Thermal blanching

Table 2 showed that there were no variations for shape of samples at different temperature treatment, but color significantly changed under treatment. At 80℃, six samples’ colors turned to PY at 90s. The worst color was DY at 150s. So this temperature treatment is suitable for blanching. When blanching lasted for 90s at 100℃, the samples’ colors were changed to PY during whole treatment period, but quality of appearance is not sufficiently satisfactory to proceed further with this treatment. We have got suitable appearance quality under the conditions of 120℃ and 90s. If time is increased beyond 150s, samples were become DY. The samples' color were deepened at 60s and at 140℃, and remained deepened at 90s. At last, samples were burned brown after 180s and had the worst appearance. We found that the best blanching treatment is a blanching time of 120s and blanching temperature of 120℃, producing best quality of flower appearance.

Table2   Effects of heat treatments at various times

Shape：full open(FO);half open (HO);shrinking(S); color：deep yellow(DY) ;yellow(Y) ;pale yellow(PY) ;white(W)

2.2 Drying

By comparison of two blanching ways, it was determined that best quality was obtained under microwave treatment of 80s and 600W. So, we chose the blanched samples from this treatment to be dried.

2.2.1 microwave drying

The Fig 1 and table 3 showed that weights of samples were stable when drying lasted for 15min under low power microwave, and color was PY, with the best appearance. If treatment time lasted beyond 25 min, colors and shapes of flowers soon deteriorate. The color of CK changed to PY just for 5 min, and deepened for 10min, resulting in the worst quality of appearance. It was very clearly demonstrated that the best treatment is a drying time of 20 min and under low power microwave.

2.2.2 Thermal drying

The Fig.1 and Table 3 showed that weights of samples were stable while drying time lasted for 120min under low temperature, and better quality of flower appearance was obtained. The samples were apparently shrinking after 150min, and color was changed to yellow; further drying for 180min resulted in the worst quality of flower appearance. After drying for 30min, samples became pale yellow, and then yellow after 90 min. If drying continued for 150 min, the quality of flower appearance was terrible.

By comparison, we found best quality was obtained by using Thermal drying for 120 min under low temperature. Furthermore, thermal drying is better than microwave drying.

3 Conclusions

A new technique for drying fresh flowers of plants in Sect. Theopsis of Theaceae was first successfully developed in our project, and we obtained the optimum condition as below: picking → cleaning → microwave blanching at 600w for 80s → thermal drying for 120min  → storage of samples. The results showed that treated flowers retain their original color and shape, thus producing great potential economic value. At present, the technique for drying flowers was developed only for saving samples for long time. In future studies we will determine nutrition such as tea polyphenols, soluble sugar, amino acid, vitamin and so on, including indexes of food security.

Acknowledgments: This work was supported by the International Cooperation Project of China (2011DFA30490), and Zhejiang Key Flower Breeding Program (2012C12909-6).

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This project was supported by Zhejiang Key Program for Breeding New Flower Varieties (No.2012C12909-6)