Influence of Temperature and Relative Humidity on Physico-chemical Characters and Fungal Spoilage of Katha

Physico-chemical characters and fungal spoilage of machiney and desi Katha dried at six different temperatures and nine relative humidity levels were studied. Catechin content was maximum and tannins were least when Katha batties were dried at 5 or 10°C. Discolouration of batties and mould incidence (Aspergillus niger and Penicillium funiculosum) was also least when drying was carried at 5°C followed by 10°C. Maximum catechin was in Katha dried at 40 and 45 per cent relative humidity. As the relative humidity during Katha drying was increased above 50 per cent, there was corresponding increase in tannins. Discolouration and catechin/tannin ratio was also least when Katha was dried at 40 or 45 per cent relative humidity. Drying at higher relative humidity (above 55%) favours invasion by A. niger and P. funiculosum moulds.