Studies of different drying methods on the quality parameter of Dutch rose

Introduction

The rose, often admired as the "Queen of Flowers," is considered one of the most beautiful creations of nature. It is a member of the Rosaceae family and falls under the genus Rosa. Globally, nearly 120 Rosa species are identified, and nearly 30,000 cultivars are grown across different regions. Roses represent love, purity, admiration and hold significant importance in cultural, religious, and social practices around the world. Because of their beauty and growing customer preference, they occupy a major share of the international cut flower market. In India, roses are cultivated on a large scale for various uses, including cut flowers, floral decorations, gulkand, rose water, garlands, worship and perfumery (Vijayalaxmi et al., 2017) [42] . Their dried petals are used to make potpourri, vinegar, and wine, while rose hips, which are rich in vitamin C, are processed into syrups, jams and jellies. Rose extracts are also extensively applied in the cosmetic and fragrance industries (Irshad et al., 2020) [14] . Rose ranks as the leading cut flower in the global flower trade in terms of both production and consumption. It is highly valued for its remarkable diversity in shape, size, color and its pleasant fragrance. Numerous value-added products can be created from dried rose flowers, including collages, floral artworks, flower balls, greeting cards, decorative covers, pomanders, festive ornaments, bouquets, wreaths and fragrant potpourri (Vishnupriya and Jawaharlal, 2014) [43] . In India, dried flower industry is as old as 40 years. But it is only the last decade that brought in a lot of changes and widened the scope of this industry. The momentum of growth was surprisingly high during the past 10 years (Kulkarni et al., 2004) [16] . The life of dried flowers varies with different flowers according to the species, texture of their petals and total consistency of flowers. The United States is the largest consumer of dried and artificial flowers, with an estimated annual expenditure of US $2.4 million, followed by Germany and the United Kingdom. Other major importing regions include Western Europe, Japan, Hong Kong and Singapore (Mishra et al., 2014) [19] . India, endowed with a rich diversity of flora, acts as a key raw material supplier for the dried flower industry and holds the potential for a market value of approximately Rs. 40 million in this sector. One of the main advantages of dried flowers is their long-lasting beauty; they can be preserved for years, enduring both winter chills and summer heat. With increasing eco-consciousness, natural and sustainable decorative options like dried flowers are becoming a preferred choice. The longevity of dried flowers depends on their species, petal texture and structural integrity. These flowers can be effectively utilized in decorative floral crafts for interior decoration as well as for commercial purposes (Ranjan and Misra, 2002) [27] . To promote eco-friendly trade, the government provides a 25% rebate on freight for dried flower products. India exports substantial quantities of raw materials to developed countries such as the UK, Japan, and the USA, where there is a high demand for dried floral arrangements (Raju, 2001) [30] . Rose flowers are traded through a well-organized international market system, providing employment opportunities for numerous entrepreneurs worldwide. Floriculture has emerged as a highly profitable profession, offering greater returns than many traditional field and horticultural crops (Dilta et al., 2011) [10] . In India, however, the export potential of the dried flower industry has largely been overlooked, and the sector remains one of the most neglected. The field holds immense prospects, and with sustained efforts, India can establish a significant presence in the global market. There is an urgent need to optimize flower drying techniques, taking into account the local flora and fauna and the prevailing climatic conditions in the country. Therefore, the present study was undertaken to standardize drying technology for Dutch roses. The quality of dried flowers is largely influenced by factors such as flower structure, moisture content, stage and time of harvest and the drying method employed. Therefore, the present study was conducted with the objective of evaluating the effects of variety, harvest stage and drying methods on the quality of dried flowers. Given the significant potential of Dutch roses in the dried flower industry, the present study was designed to determine the most effective drying method, the most suitable cultivar and the optimal drying duration using microwave, hot air oven, and air-drying techniques. Flowers, as natural symbols of human emotions, contribute greatly to aesthetic appeal and help create an ecofriendly environment. With the increasing global demand for flowers, the industry is experiencing rapid growth. However, fresh flowers are costly, highly perishable, and not available year-round in all regions (Datta, 2019). To ensure year-round availability and extend the longevity of flowers, drying is considered one of the most effective preservation methods.

Dried flowers retain their aesthetic appeal and are long-lasting regardless of season (Koley, 2020). Among cut flowers, Dutch rose is highly valued for its vibrant colour, uniform bloom, long stalk and excellent vase life, making it a top choice in both domestic and export markets. Dutch roses are mainly grown under protected conditions, such as polyhouses, in states like Karnataka, Gujarat, West Bengal and Chhattisgarh to meet the high demand during special occasions, including Valentine's Day, Christmas and weddings. Protected cultivation helps reduce the effects of climate-related stresses, such as heat, drought and pest infestations, while ensuring consistent production of high-quality flowers. Although fresh roses are visually appealing, they are highly perishable and not available throughout the year. Drying offers a way to preserve their ornamental value and fulfill year-round decorative requirements. With increasing eco-consciousness, dried flowers are becoming more popular for home décor, crafts, and commercial products due to their natural beauty and long shelf life (Mahapati et al., 2015) [18] . Considering the commercial significance of Dutch roses and the limitations in the availability of fresh flowers, the present study aims to evaluate different drying techniques microwave, hot air oven and air drying to produce high-quality dried Dutch rose flowers under naturally ventilated polyhouse conditions. The study also examines the performance of various cultivars in Karnataka's Northern dry zone, where high summer temperatures restrict rose cultivation (Datta, 2004; Datta et al., 2007) [12,11] . The lowest fresh and dry weights were observed in T₁ (Room drying without desiccant), likely due to slow moisture loss leading to excessive shrinkage and petal damage.

Materials and Methods

Room drying treatments retained the highest residual moisture, indicating slow dehydration, which could lead to microbial growth. T₁₃ (Hot air oven drying at 45 °C with silica gel) showed the lowest moisture content, suggesting rapid and uniform water removal, which is crucial for long-term preservation. Sun drying (T₆) and oven drying at 40 °C resulted in intermediate moisture levels, indicating partial dehydration but not as efficient as 45 °C with desiccants.

The moisture loss was significantly influenced by different drying methods and use of desiccants. Among all treatments, the highest moisture loss was recorded in T₁ (Room drying without desiccant, 66.67%), which was statistically at par with T₂ (Room drying with silica gel, 65.64%), T₃ (Room drying with borax, 65.80%), and T₄ (Room drying with sand, 65.87%). The lowest moisture loss was observed in hot air oven drying at 45 °C, particularly T₁₃ (with silica gel, 61.40%), which was statistically at par with T₁₄ (with borax, 62.76%) and T₁₅ (with sand, 63.00%).

The largest flower diameter was recorded in T₁₃ (Hot air oven drying at 45 °C with silica gel, 4.12 cm), which was statistically at par with T₁₄ (Hot air oven drying at 45 °C with borax, 4.02 cm) and T₁₅ (Hot air oven drying at 45 °C with sand, 3.98 cm). Room drying caused significant shrinkage with the smallest diameters (3.52 cm).

The minimum reduction in flower diameter was recorded in T₁₃ (Hot air oven drying at 45 °C with silica gel, 0.184 cm), which was statistically at par with T₁₄ (Hot air oven drying at 45 °C with borax, 0.195 cm) and T₁₅ (Hot air oven drying at 45 °C with sand, 0.214 cm). Room drying treatments, including T₂ (with silica gel, 0.437 cm), T₃ (with borax, 0.455 cm), T₄ (with sand, 0.470 cm), and T₁ (without desiccant, 0.490 cm), recorded the highest reductions in flower diameter, indicating greater shrinkage under slow drying conditions.

Flower color

The results revealed that the most intense and desirable color was retained in T₁₃ (Hot air oven drying at 45 °C with silica gel), T₁₄ (Hot air oven drying at 45 °C with borax), and T₁₅ (Hot air oven drying at 45 °C with sand), all exhibiting dark yellow coloration. Room drying treatments, T₁ (without desiccant), T₂ (with silica gel), T₃ (with borax), and T₄ (with sand), exhibited bronze yellow to raisin yellow coloration.

Flower shape

The most desirable high-centered blooms were observed in T₁₃ (Hot air oven drying at 45 °C with silica gel), T₁₄ (Hot air oven drying at 45 °C with borax), and T₁₅ (Hot air oven drying at 45 °C with sand). These treatments were significantly superior to all other drying methods in maintaining the natural, aesthetic form of the flowers. Room drying treatments, including T₁ (without desiccant), T₂ (with silica gel), T₃ (with borax), and T₄ (with sand), produced cupped blooms, showing maximum distortion and shrinkage of petals due to slow and uneven moisture loss.

Petal texture and quality

Results revealed that the finest flower texture was recorded in T₁₃ (Hot air oven drying at 45 °C with silica gel), T₁₄ (Hot air oven drying at 45 °C with borax), and T₁₅ (Hot air oven drying at 45 °C with sand), which were rated as fine texture.

Overall appearance

The appearance of flowers was significantly influenced by different drying methods. The most attractive and bright flowers were observed in T₁₃ (Hot air oven drying at 45 °C with silica gel), T₁₄ (Hot air oven drying at 45 °C with borax), and T₁₅ (Hot air oven drying at 45 °C with sand), which were rated as having more bright colour. Resulted in moderate colour fading, while room drying treatments T₁ (without desiccant), T₂ (with silica gel), T₃ (with borax), T₄ (with sand) produced flowers with dull or more faded colours, reflecting significant pigment degradation due to prolonged drying at ambient conditions.

Conclusion

The study revealed that the hot air oven drying treatment T₁₃ (Hot air oven drying at 45 °C with silica gel) consistently produced the best results across all flower quality parameters of Dutch rose, which was statistically at par with T₁₄ (Hot air oven drying at 45 °C with borax) and T₁₅ (Hot air oven drying at 45 °C with sand). These treatments maintained maximum fresh (8.26 g) and dry weight (3.19 g), lowest residual moisture (61.40%) and highest flower diameter (4.12 cm) with minimal reduction (0.184 cm), intense dark yellow color, high-centered bloom shape and fine petal texture, resulting in the most attractive overall appearance. In contrast, room drying treatments T₁ (without desiccant), T₂ (with silica gel), T₃ (with borax) and T₄ (with sand) exhibited the lowest flower weight, highest moisture content, greater shrinkage, duller coloration, cupped blooms and poorer petal texture, highlighting the inefficiency of slow ambient drying for maintaining ornamental and structural quality. Overall, hot air oven drying at 45 °C with silica gel T₁₃ proved to be the most effective method for preserving Dutch rose flowers, ensuring superior quality and long-term storage potential.

References

1. Acharya P, Biswas S, Saha S, Chakraborty L. Studies on methods of dehydration of rose buds Gold Medal and Minu Parle. Department of Horticulture. Institute of Agricultural Science, University of Calcutta. 2013;35.
2. Aprajita K, Kishtwaria J, Raj D, Rana A, Dadwal M. Study on different methods of dehydration of Acroclinum flower. Journal of Ornamental Horticulture. 2010;13(3):223-227.
3. Batra A. Dissemination of dry flower technology for societal good. International Journal Research Bioscience and Plant Biology. 2016;3(5):97-101.
4. Batra A. To study the behaviour of colour change in some dehydrated ornamental flowers. International Journal of Latest Research in Science and Technology. 2015;4(4):141144.
5. Boyar S, Bayhan AK, Dikmen E. Investigation on drying behavior of Isparta rose flower (Rosa damascene Mill.) under natural shade conditions. Bulg Journal of Agriculture Science. 2010;19(2):361-374.
6. Bhalla R, Moona, Dhiman SR, Thakur KS. Standardization of drying techniques of Chrysanthemum (Dendranthema grandiflorum Tzvelev). Journal of Ornamental Horticulture. 2006;9(3):159-163.
7. Bhattacharjee SK, De LC. Dried flowers and plant parts. Advanced Commercial Floriculture. 2003;162-173.
8. Crepean A. Methods of preserving roses. International Journal Current Research Bioscience Plant Biology. 2016;3(5):97-101.
9. Dilta BS, Behera TB, Gupta YC. Effect of embedding media, temperature and durations on hot air oven drying of Rose (Rosa hybrid L.) cv. "First Red". 2014;4(1).
10. Dilta BS, Sharma BP, Baweja HS, Kashyap B. Flower drying technique -A review. International Journal of Farm Science. 2011;1(2):1-16.
11. Dhatt KK, Singh K, Kumar K. Studies on methods of dehydration of rose buds. Journal of Ornamental Horticulture. 2007;10(4):264-267.
12. Datta SK. Dehydration of flowers: A new diversified product for floriculture industry. Emerging Trends in Ornamental Horticulture. Indian Society of Ornamental Horticulture. 2004;157-161.
13. Dahiya DS. Dehydration of annual chrysanthemum. Acta Horticulturae. 2003;624:385-387.
14. Irshad M, Subhani MA, Ali S, Hussain A. Biological importance of essential oils. Essential Oils -Oils of Nature. 2020;1.
15. Jain R, Jankiraman T, Kumawat GL. Drying techniques in ornamental plants. Commercial Horticulture. 2016;501-502.
16. Kulkarni SB, Patil VK, Reddy SB. Studies on drying of marigold (Tagetes erecta) flowers. National Symposium on Recent Trends and Future Strategies in Ornamental Horticulture. Indian Society of Ornamental Horticulture, New Delhi. 2004;Abstracts:123.
17. Lee WY, Yoon M, Pak C, Kwack B. Effects of various drying methods for wild flowers. Korean Journal Horticulture Science Technology. 2003;21:50-56.
18. Mahapati S, Naik BH, Chougala S, Pujeri US, Shivakuma. Standardization of drying temperature and time in hot air oven of gerbera var. impireal. 2015;4(12).
19. Mishra S, Dwivedi AK, Kulshreshtha K. To study the effect of texture of flower petal and moisture content during floral dehydration. International Journal of Latest Research in Science and Technology. 2014;3(2):144-146.
20. Nair B, Singh KP. Aesthetic quality of chrysanthemum flowers as affected by the dessicants. Agronomy Crop Science. 2011;2(2):12-18.
21. Nirmala AR, Chandrasekha M, Padma, Rajkumar M. Standardization of drying techniques of carnation (Dianthus caryophyllus). Journal Ornamental Horticulture. 2008;11:168-172.
22. Nataraj SK, Kulkarni SB, Gangadharappa PM, Reddy BS, Hegde NK, Mathad GV. Standardization of drying techniques in Nerium oleander. National Symposium on Recent Trends and Future Strategies in Ornamental Horticulture. Indian Society of Ornamental Horticulture, New Delhi. 2004;Abstracts:121.
23. Panse VG, Sukhatme PV. Statistical methods for agricultural workers. ICAR; 1985.
24. Renuka SKJ, Arya CK. Effect of drying techniques and embedding media on dried flower quality of rose (Rosa chinensis Jacq.) and water lily (Nymphaea alba L.). Horticulture Floriculture Research Spectrum. 2016;5(4):289-294.
25. Radharani P, Mahalakshmi V, Reddy. Dehydration techniques for flowers. International Journal of Applied Research. 2015;1(10):306-311.
26. Ravichandra S, Pedapati A. Effect of pre-drying treatment on carnation dried flower quality. 2014.
27. Ranjan JK, Mishra S. Dried flowers: A way to enjoy their beauty for a long period. Indian Horticulture. 2002;46:3233.
28. Raghava SPS. Floriculture -a viable diversification option in agri-business. Indian Horticulture. 2001;45:44-45.
29. Raj D. Making floral crafts from forest products of the Himalayas. Indian Horticulture. 2001;46:26-27.
30. Raju MS. Standardization of drying techniques for China aster cut flower. MSc Thesis, University of Agricultural Sciences, Bangalore. 2001;25-31.
31. Raghupathy R, Amuthan G, Kailappan R. Dried flowers: Significance. Kisan World. 2000;27:39.
32. Sindhuja S, Padmalata T, Padmavathamma AS. Effect of embedding media on production of quality dry flowers in carnation. Plant Archives. 2015;15(1):27-33.
33. Singh I. Drying behaviour of French marigold (Tagets patuala Linn) flowers. International Journal of Farm Sciences. 2014;4(2):100-106.
34. Safeena SA, Patil VS. Studies on the effect of microwave oven drying on flower quality of dried Dutch rose flowers. Natl Acad Sci Lett. 2014;37(1):19-24.
35. Safeena SA, Patil VS. Effect of hot air oven drying on production of quality dry flowers of Dutch roses. Journal of Agriculture Science. 2013;5(4):16-23.
36. Song C, Qin Y, Chen X, Zhou L. Effect of vacuum microwave (VMV) drying on quality of rose. International Conference on Agricultural and Biosystems Engineering Advances in Biomedical Engineering. 2011;1-2:144.
37. Safeena SA, Patil VS. Suitability of Dutch rose varieties for dry flowers. Karnataka Journal Agriculture Science. 2007;10:105-108.
38. Safeena SA, Patil VS, Hemlanaik B. Standardization of stage of harvest for better quality of dry flowers of rose. Journal of Ornamental Horticulture. 2006;9(3):224-226.
39. Safeena SA, Patil VS, Hemlanaik B. Response of drying in hot air oven on quality of rose flowers. Journal of Ornamental Horticulture. 2006;9(2):114-117.
40. Singh A, Dhatuk BK. Effect of dehydration techniques in some selected flowers. Journal of Ornamental Horticulture. 2005;8(2):155-156.
41. Singh A, Dhatuk BK, Shah RR. Effect of dehydration on post harvest life and quality of zinnia flowers. Journal of Ornamental Horticulture. 2003;6(2):141-142.
42. Vijayalaxmi GP, Seetaramu GK, Balaji SK. Performance of floribunda roses for yield parameters under north eastern transitional zone of Karnataka. Plant Architecture. 2017;17(2):11.
43. Vishnupriya K, Jawaharlal M. Glycerinization of foliages for dry flower products making. The Bioscan. 2014;9(2):507-511.
44. Wilson D, Attri BL, Sharma SK. Evaluation of different methods for drying of chrysanthemum flowers. The Asian Journal of Horticulture. 2013;8(2):743-745.