Comparative Effects of Oven and Microwave Drying on Nutrient Retention and Consumer Acceptability of Watermelon (Citrullus Lanatus)

Background: Watermelon (Citrullus lanatus) is a nutrient-rich fruit with a high moisture content (~92%), making it highly perishable and prone to post-harvest losses. Preservation through drying can reduce spoilage; however, the choice of drying method and pre-treatment may impact nutrient retention and sensory quality. Methods: This study assessed the effects of oven drying at 54°C and microwave drying at 60°C on the proximate composition, mineral content (iron, calcium), vitamin retention (vitamin C, β-carotene), total soluble solids (TSS), and sensory attributes of watermelon slices, both untreated and pre-treated with ascorbic acid solution (3 g/250 ml). Analyses followed AOAC-standardized methods, while sensory evaluation was conducted by a 15-member trained panel using a 9-point hedonic scale. Results: Oven drying retained higher vitamin C (24.53 mg/g) and β-carotene (14.56 mg/g) compared to microwave drying (16.78 mg/g and 8.56 mg/g, respectively) (p < 0.05). Ascorbic acid pre-treatment improved iron retention (1.62 mg/g in oven-dried slices) but reduced vitamin stability. Sensory scores were highest for untreated oven-dried samples, with appearance (8.33), taste (7.87), and overall acceptability (8.00) outperforming other treatments. Microwave drying reduced processing time but increased TSS (88.47°Brix) and negatively affected sensory attributes. Conclusion: Oven drying without chemical pre-treatment is recommended for optimal nutrient preservation and consumer acceptability in dehydrated watermelon products.

Watermelon dehydration; Oven drying; Microwave drying; Ascorbic acid pre-treatment; Nutrient retention; Sensory evaluation

1. Maranesi M, Magnani M, Chiarini F. Chemical characterization and bioactivity of seeds from watermelon fruits. International Journal of Food Science & Technology, 50(7): 1543–1551, 2015. https://doi.org/10.1111/ijfs.12804 [Google Scholar] [Crossref]

2. Singh, K. (2024). Dose-Response Effect of Watermelon Consumption on Ambulatory Blood Pressure in Adults With Pre-Hypertension: A Randomized Controlled Pilot Trial (Master's thesis, Illinois Institute of Technology). [Google Scholar] [Crossref]

3. Lovato, F., Kowaleski, J., da Silva, S. Z., Kottwitz, L. B. M., Martin, C. A., Tiuman, T. S., & Zara, R. F. (2025). Watermelon juice microfiltration: optimization to maximize antioxidant compounds and influence mineral content. Journal of Food Science and Technology, 1-10. [Google Scholar] [Crossref]

4. Srivastava, P. K., & Sit, N. (2025). A review on fruit and vegetable processing using traditional and novel methods. Future Postharvest and Food, 2(1), 4-26. [Google Scholar] [Crossref]

5. Aslan, M., Önal, Y., Akbulut, Y., & Başar, C. A. (2021). INVESTIGATION OF DRYING KINETICS OF APRICOTS IN DIFFERENT ENVIRONMENTS. İnönü Üniversitesi Sağlık Hizmetleri Meslek Yüksek Okulu Dergisi, 9(2), 385-401. [Google Scholar] [Crossref]

6. Tufan, E. G., Borazan, A. A., & Koçkar, Ö. M. (2021). A review on edible film and coating applications for fresh and dried fruits and vegetables. Bilecik Şeyh Edebali Üniversitesi Fen Bilimleri Dergisi, 8(2), 1073-1085. [Google Scholar] [Crossref]

7. Ankeli, J. A., Igbum, O. G., & Okibe, F. G. (2025). Comparative Effects of Drying Methods on Physicochemical Properties of Puree Blends of Some Indigenous Varieties of Watermelon (Citrullus lanatus), Orange (Citrus sinensis) and Mango (Mangifera indica) Fruits. Journal of Agriculture, Aquaculture, and Animal Science, 2(1), 15-29. [Google Scholar] [Crossref]

8. Liu, L., & Xi, J. (2021). Mechanochemical-assisted extraction of protein from watermelon seeds with surfactant. Lwt, 142, 111025. [Google Scholar] [Crossref]

9. Matouk, A. M., El-Khouly, M. M., Tharwat, A., El-Shenawy, M. A., & Elfar, S. E. (2022). Thin layer infrared drying of crimson seedless grapes. Journal of Soil Sciences and Agricultural Engineering, 13(9), 303-310. [Google Scholar] [Crossref]

10. Oprică, L., Grigore, M. N., VochiȚA, G., Jijie, R., & Popovici, L. F. (2023). Biochemical responses of Silybum marianum seedlings to independent and combined salt and SiO2 treatments. Notulae Botanicae Horti Agrobotanici Cluj-Napoca, 51(3), 13375-13375. [Google Scholar] [Crossref]

11. Association of Official Analytical Chemists. Official Methods of Analysis (18th ed., Methods 932.12, 932.14), 2005. [Google Scholar] [Crossref]

12. Hasan, M. M., Ara, R., Sayem, A. S. M., & Alam, M. (2025). Maximizing quality in dried tomatoes: Evaluating the effects of immersion pretreatments on physicochemical attributes, antioxidant capacity, and microbial load. Food Bioscience, 64, 105982. [Google Scholar] [Crossref]

13. Duraivel, B., Muthuswamy, N., & Gnanavendan, S. (2024). Comprehensive analysis of the greenhouse solar tunnel dryer (GSTD) using Tomato, snake Gourd, and Cucumber: Insights into energy Efficiency, exergy Performance, economic Viability, and environmental impact. Solar Energy, 267, 112263. [Google Scholar] [Crossref]

14. Khama, R., Aissani-Benissad, F., Alkama, R., Fraikin, L., & Léonard, A. (2022). Modeling of drying thin layer of tomato slices using solar and convective driers. Agricultural Engineering International: CIGR Journal, 24(1). [Google Scholar] [Crossref]

15. Dai, Y., Lu, X., Li, R., Cao, Y., Zhou, W., Li, J., & Zheng, B. (2022). Fabrication and characterization of W/O/W emulgels by sipunculus nudus salt-soluble proteins: Co-encapsulation of vitamin C and β-carotene. Foods, 11(18), 2720. [Google Scholar] [Crossref]

16. Raj, G. B., & Dash, K. K. (2022). Effect of intermittent microwave convective drying on physicochemical properties of dragon fruit. Food Science and Biotechnology, 31(5), 549-560. [Google Scholar] [Crossref]

17. Carvalho, M. J. (2021). Practical handbook sensory analysis. [Google Scholar] [Crossref]

18. Osman, O. A., Sulieman, A. M. E., & Ahmed Osman, O. (2023). Principles and Techniques of Sensory Evaluation for Assessing the Quality of Halalfoods. In Halal and Kosher Food: Integration of Quality and Safety for Global Market Trends (pp. 175-188). Cham: Springer International Publishing. [Google Scholar] [Crossref]

19. Delfiya, D. A., Prashob, K., Murali, S., Alfiya, P. V., Samuel, M. P., & Pandiselvam, R. (2022). Drying kinetics of food materials in infrared radiation drying: A review. Journal of Food Process Engineering, 45(6), e13810. [Google Scholar] [Crossref]

20. Badin, E. E., Quevedo-Leon, R., Ibarz, A., Ribotta, P. D., & Lespinard, A. R. (2021). Kinetic modeling of thermal degradation of color, lycopene, and ascorbic acid in crushed tomato. Food and Bioprocess Technology, 14(2), 324-333. [Google Scholar] [Crossref]

21. Karimi, R., Mirbagheri, S. M., & Davtalab, M. (2022). Pre-harvest Application of Potassium and Iron Promotes Phenolic Acids and Anthocyanidin Accumulation and Boosts Antioxidant Capacity in Raisin Produced from ‘Red Sultana’Grape (Vitis vinifera L.). International Journal of Horticultural Science and Technology, 9(3), 315-328. [Google Scholar] [Crossref]

22. Wiset, L., Poomsa-ad, N., & Onsaard, W. (2021). Drying characteristics and quality evaluation in microwave-assisted hot air drying of cherry tomato. Engineering and Applied Science Research, 48(6), 724-731. [Google Scholar] [Crossref]

23. Somjai, C., Siriwoharn, T., Kulprachakarn, K., Chaipoot, S., Phongphisutthinant, R., & Wiriyacharee, P. (2021). Utilization of Maillard reaction in moist-dry-heating system to enhance physicochemical and antioxidative properties of dried whole longan fruit. Heliyon, 7(5). [Google Scholar] [Crossref]

24. Kazosi, M. (2023). Development of dried African nightshade products for post-harvest loss reduction and shelf-life extension in Tanzania (Doctoral dissertation, NM-AIST). [Google Scholar] [Crossref]

• Bamboo Shoots (Bambusa Vulgaris) Bites: A Flavorful Twist On Siomai