Analysis of traditional food additive kolakhar for its physico-chemical parameters and antimicrobial activity

Kolakhar had been prepared from banana plants and used by people of Assam since time immemorial. This work has investigated its physicochemical properties as well as its activity against pathogenic micro-organisms. This highly alkaline preparation is found to contain high amount of alkali elements and significant quantity of vanadium and zinc along with its inhibitory property against the tested strains. The bioactivity of kolakhar may be attributed to its very high pH due to its metal content. Thus, this traditional food additive has potential therapeutic applications along with providing the trace element like vanadium.


Introduction
Kolakhar is a traditional ingredient and a popular food additive in Assam. This antacid is made by filtering water through the ashes of a banana tree (the name derived from the local term of Banana, "kol" or "kola"). It can be made from banana stem, Mudiar Rinky Hemanta, Varsha Kelkar Mane, Ashok Bhagwat-Analysis of traditional food additive kolakhar for its physico-chemical parameters and antimicrobial activity rhizome & peel. Amongst the available varieties of banana in North East region, khar made from Musa balbisiana Colla (a wild variety heavily seeded banana tree) has the best quality.
Along with its routine use as food additive in cooking, kolakhar has been used to treat various ailments. It is used to normalize digestive disorders of stomach and to prevent bacterial attacks on freshly cut injury to heal fast. Use of kolakhar as soaps and detergent for washing clothes and shampooing hair has been practiced in villages. It is also used by farmers to kill leaches and prevent their attack while working in leech infected fields. It also cures and prevents certain cattle diseases 1 .
M. balbisiana (athiya kol/ bhim kol) is an indigenous variety of banana in Assam. Young banana pseudo-stem is cooked as vegetable (called posola) which is a very rich source of iron and fibers. Rhizomous stem exudates intake of this plant treat dysentery 2 , pinworm infection 2 as well as sore throat. Ability of liquid exudates of banana trunk in treating infertility in males has also been reported. Banana plant has been found to possess insecticidal 3 , anthelminthic 4 , anti-ulcerogenic, anti microbial 5 , anti-venom, anti-allergic, anti-hyperlipidemic, antidiebetic 6 , anti-oxidant 5.7,8 as well as anti cancer properties.
Banana and its pseudo-stem contain pathogenesis proteins possessing antimicrobial properties. However, bioactivity of kolakhar against micro-organisms has not been reported yet. Till date, only chemical investigation of kolakhar has been carried out 1 .

Objective:
The current research focuses on the physicochemical parameters of the food additive as well as anti-microbial effect of kolakhar on various pathogenic micro-organisms.

Methodology
Sample preparation: kolakhar was prepared by traditional method. Briefly, pseudo-stem of a mature healthy tree of M. balbisiana was collected (from Kahilipara, Guwahati, Assam), cut into pieces and kept under sun drying for 10 days. After complete drying, the pieces were burned into ashes and sieved. 50gm of this ash was suspended in 100ml sterile deionized water and filtered through muslin cloth. This filtrate (50% aqueous extract) is referred to as kolakhar and it can be stored at RT for a year.

Physicochemical analysis:
The kolakhar sample was tested for physicochemical characteristics namely pH, electrical conductivity (EC), Total solids (TS), Total alkalinity, Total hardness, Na + , K + and Clcontent. The reagents used were of AR grade and deionized water was used for reagent preparation.
Elemental analysis: The sample was analyzed for Zn, Pb, Cd, As and V using inductively coupled plasma atomic absorption spectroscopy (AAS). The analysis was carried out in SAIF (IIT, Bombay).

Bioassay:
The activity of kolakhar on micro-organisms was checked by agar cup method. Nine pathogenic strains of microorganisms were inoculated in MH agar (from Hi-Media) and 0.1ml sample was added to the wells of 10mm diameter. The plates were kept for pre-diffusion under refrigeration. After incubation at 37 0 C for 24 hours, the diameters of zone of inhibition were measured. Sterile distilled water was taken as control for experiment.

Result and discussions
The results for physicochemical, elemental and bioassay are presented in table 1, 2 and 3 respectively.   Kolakhar prepared from M. balbisiena was found to have very high pH (pH 13.0). Also, the sample was found to contain significant amount of vanadium and zinc. Banana plant is accumulating the elements from soil and water and hence contributing to its high amount in the Kolakhar. This bio-antacid was found to inhibit the growth of the pathogens used. The bioactivity of Kolakhar may be attributed to its high alkalinity which is mainly due to its alkali element such as potassium, sodium, calcium, carbonate, chloride etc. P. aeruginosa was found to be more sensitive towards kolakhar followed by others.
Hence, these results evaluate the use of this traditional food additive among the native people of Assam.