Effects of drying techniques and storage on raw material safety and stability of phytochemicals of hempedu bumi (Andrographis paniculata (Burm.f.) Wall. ex Nees)

Controlling the quality of finished herbal products with regard to safety aspect begins with proper production, harvesting and postharvest handling systems. However, there is very limited information that gives an overview on the safety and quality of hempedu bumi or Andrographis paniculata focusing on drying techniques and storage duration. Therefore, the objective of this study was to ascertain the effects of drying and storage on safety and stability of phytochemicals of A. paniculata. In terms of safety aspects, heavy metal contaminations showed that Al, As, Cr, Cu, Hg, Ni, Pb and Zn were detected in soil and only Al, Cr, Cu, Ni and Zn found in tissues. Sample collected from Jabatan Pertanian, Serdang, Selangor had less concentrations of Al, Zn, Cr and Cu than Taman Pertanian Universiti (TPU), Universiti Putra Malaysia, Serdang and Kg. Bukit Pulau, Melaka. On the other hand, microbial contaminations depended on the drying technique used and however, increased during storage. Total count of fungi, yeast and bacteria also specific bacteria, Escherichia coli and Staphylococcus aureus were found less in vacuum oven and freeze drying throughout storage. Fortunately, heavy metal and microbial contaminations of dried A. paniculata were within the permissible limits prescribed by WHO. The quality of A. paniculata leaf colour was greatly affected by drying techniques. The leaf colour of freeze-dried samples was much better than other drying techniques, with bright and greenish colour leaves. In addition, the chemical markers of andrographolide (AG) and neoandrographolide (NAG) content of freeze-dried samples were found to be more stable during storage compared to 14-deoxy-11, 12-didehydroandrographolide (DDAG). Microbial contaminations had a significant negative correlation with AG content, which indicating that the presence of microorganism may led to the decreased in AG. Apart of this, freeze-dried samples also showed highest content of TPC, TFC and antioxidant activities (DPPH and FRAP) throughout the storage duration. However, sun drying gave the highest content of DDAG and TFC throughout storage period as compared to vacuum and conventional oven drying techniques. This study also showed high correlation between TPC and TFC which demonstrated that antioxidant activities were contributed by phenolic and flavonoid compounds. Therefore, sun and freeze dryings were selected for future optimization of their quality using proton nuclear magnetic resonance (1H-NMR). Eight compounds were identified in both techniques. Result obtained in PCA revealed that freeze-dried samples had higher amounts of AG and NAG, and also with relatively high amount of chlorogenic acid and alanine. AG, NAG and alanine compounds in freeze-dried samples were optimum within 6 to 8 weeks of storage. Chlorogenic acid, a compound related to antioxidant activities was found increased with storage duration. However, sun-dried samples were rich in DAG and glucose compounds, where, the estimated optimum amount of these compounds was found within 5 to 6 weeks of storage. Conversely, the level of choline in sundried samples increased with storage period. Thus, freeze drying is considered to be an appropriate technique for drying A. paniculata commercially, because this technique can stabilize most of the phytochemicals, at the same time safe for consumption.

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