Comparative Evaluation of Drying Techniques for Maximizing Nutrient Retention and Phytochemical Profiles in Two Medicinal Tulsi Varieties: An Approach to Reduce Post-Harvest Loss

Abstract

Objective:
Tulsi (Ocimum sanctum and Ocimum tenuiflorum) is a pharmacologically important adaptogenic herb with a diverse phytochemical profile and several potential therapeutic applications. However, inappropriate drying practices may adversely affect its nutritional quality, antioxidant potential, and bioactive compounds. This study aimed to compare different drying techniques and identify the most effective method for preserving the nutritional and phytochemical properties of Rama and Krishna Tulsi leaves.
Methods:
Fresh leaves of Rama and Krishna Tulsi were subjected to five drying methods: sun drying, pan drying, hot air oven drying, oven drying at 100°C, and oven drying at 120°C, with fresh leaves serving as controls. The resulting powders were evaluated for proximate composition, functional properties, mineral content, qualitative and quantitative phytochemical constituents, and volatile bioactive compounds using Gas Chromatography-Mass Spectrometry (GC-MS).
Results:
Drying technique influenced the nutritional and phytochemical composition of both Tulsi varieties. Krishna Tulsi dried at 100°C demonstrated superior retention of protein, while Rama Tulsi showed greater retention of carbohydrates under the evaluated drying conditions. GC-MS analysis revealed variations in the volatile bioactive compound profiles across the different drying treatments, with moderate thermal processing showing comparatively better preservation of bioactive constituents.
Discussion:
The findings indicate that drying temperature and processing conditions play an important role in determining the nutritional and phytochemical quality of Tulsi powders. Oven drying at 100°C provided a favorable balance between moisture removal and retention of key nutritional and bioactive constituents, particularly in Krishna Tulsi. These findings highlight the importance of selecting an appropriate post-harvest drying method to minimize quality deterioration and enhance the functional value of Tulsi for food and nutraceutical applications.
Conclusion:
Oven drying at 100°C was identified as the most effective drying technique for preserving the nutritional quality and phytochemical composition of Krishna Tulsi under the conditions evaluated. The findings support the use of controlled thermal drying as a standardized post-harvest processing approach for developing value-added functional foods and nutraceutical products from Tulsi leaves.