Evaluation of the Physical Properties of Benjakul Decoction and the Possibility of Contamination with Heavy Metals

Abstract

This study involved an evaluation of the physical properties of the Benjakul decoction, the Sa-Moure-Pak recipe (equal proportions) based on the Sa lung and Baht formulae. It was aimed at achieving basic information for users. The raw herbal materials were placed in either a clay pot or beaker for comparison.
Water was added just to cover the herbs and boiled until the volume of liquid was one third of the original. It was found that the volume used could differ depending on the size of the container selected and the water volume used to cover the herbs. The boiled herbal solution in the beaker gave a more intense color and a higher acidic pH compared with the pre-boiling mixture (p<0.05). When immersing the herbs in water for 60 minutes, the herbal solution showed more intense color and more acidity compared with pre-immersion, but the acidity of the herb-immersed solution was less than that produced by the boiling method. Boiling the mixture in the clay pot produced a clear color and more basic pH. However, the pH of the water before and after boiling in the clay pot was found to be similar and was basic (pH ~ 8-9). When boiling herbs following the Sa lung and Baht protocols in a clay pot, the color of the herbal solution was more intense and more acidic than at pre-boiling (p<0.05). However, the acidity of the boiled herbal solution in the clay pot was less than that in beaker. This demonstrated that the clay pot could absorb twice as much water as the clay pot that was previously soaked in water overnight and allowed to dry in the air before use. The raw herbal materials were also found to absorb water such that their weight increased two-fold after boiling. There was no fungal contamination of the boiled herbs or the solution. However, such contamination was found in herbs and solution that were not boiled after keeping them in a refrigerator for one week. The amounts of heavy metals, i.e., lead, cadmium and arsenic, found in the raw herbal materials and in the clay pot were in trace amounts and less than the limits set in the Thai Herbal Pharmacopoeia II. In conclusion, the decoction produces a higher yield of substances from herbs and helps eliminate fungal contamination that might be present in herbal materials and containers, or occur in the process of preparation.