Influence of drying methods and packaging materials on physico-chemical properties and phytochemical composition of Kalmegh [Andrographis paniculata (Burm. f.) Wall. ex Nees] for shelf life enhancement

Kalmegh [Andrographis paniculata (Burm. f.) Wall. ex Nees] is known for its innumerable medicinal properties and is usually consumed in semi-processed form. Inadequate post harvest operations leads to the deterioration of quality rendering the product unsafe for consumption. Hence, in the present study the impact of washing of the herb, drying methods and packaging materials on the physico-chemical properties and phytochemical composition of Kalmegh-fresh during storage was analyzed. Fresh areal biomass of Kalmegh was subjected to five different methods of drying viz., shade, sun, solar and oven drying and five methods of packaging viz., gunny bags, polypropylene, LDPE, HDPE containers and corrugated box (CFB). The samples were subjected for physico-chemical and phytochemical analysis before drying, after drying and during storage [3, 6, 9 and 12 months after storage (MAS)]. Among different drying methods, shade drying took maximum drying time of around 22 days to reach the desired moisture content (<10%) while, drying was fast in oven drying (45°±1°C) method (2 days). No significant differences were observed for moisture, chlorophyll and andrographolide content in the stored samples with and without washing even at 12 MAS. During storage, absorption of moisture was more in shade dried samples and packed in LDPE container (11.26%) and gunny bags (11.04%), whereas, it was less in oven dried samples (8.67%) and packed in HDPE container (9.52%). Retention of chlorophyll a and b contents after drying and even at 12 months after storage was observed in shade dried samples (1.48 and 1.22 mg/g, respectively) and stored in HDPE container (1.41 and 1.2 mg/g, respectively). During storage, andrographolide content tends to decrease as the storage period increases from 3–12 months. Reduction in the andrographolide content after drying to 12 MAS varied from 10.42–54.12% in different drying methods followed. However, shade dried samples packed in HDPE container retained the maximum andrographolide content (1.53%) even after 12 MAS. Hence, from the present study it can be inferred that among the different methods employed, shade drying and packaging in HDPE container were best methods of drying and packaging of Kalmegh to retain the quality if the dried herb up to 12 MAS.