Abstract
Sandhan Kalpana, a unique pharmaceutical process in Ayurveda, represents the classical art of natural fermentation used for preparing self-generated alcoholic and acidic formulations. Preparations such as Asava and Arishta exemplify this concept, where herbal decoctions or juices undergo controlled fermentation without the addition of external alcohol. Sweetening agents like Guda (Jaggery) or Madhu (Honey) act as substrates, while fermentative agents such as Dhataki (Woodfordia fruticosa) initiate and sustain the process. The self-generated ethyl alcohol formed during fermentation serves as a natural preservative and efficient bioenhancer, improving the extraction, assimilation, and therapeutic potency of the herbal constituents.A comparative analysis of classical Sandhan Kalpana and modern fermentation techniques reveals remarkable similarities in principles of microbial metabolism, substrate utilization, and process optimization. Ancient Ayurvedic scholars demonstrated a sophisticated understanding of biochemical transformation, environmental control, and product stability long before the development of modern microbiology. The traditional process, though empirical, aligns closely with modern biotechnological concepts such as anaerobic fermentation, microbial enzymatic action, and metabolite regulation. Reinterpreting classical Sandhan Kalpana through a modern scientific lens emphasizes its potential contribution to standardization, quality assurance, and innovation in Ayurvedic pharmaceutics. Bridging these two knowledge systems can lead to the development of novel, naturally fermented herbal formulations with enhanced efficacy and global therapeutic acceptance.

Key words: Ayurveda, Asava and Arishta, Fermentation, Sandhan Kalpana.