Superheated steam blasting for cleaning and sterilization of clay pots used for curd packaging

Abstract

Use of hygienic packaging materials is very important to avoid microbial contaminations that lead to poor shelf life of curd. Microbial and dust contaminations in clay pots are found to be a major problems in using them for curd packaging and therefore proper cleaning and sterilization of clay pots is essential. The present method of washing, potassium sobate treatment and re-firing is not satisfactory due to poor shelf life of curd and high cost of production. Therefore, the main objective of this experiment was to evaluate the effectiveness of steam injection for cleaning dust and sterilization at once of the clay pots used for curd packaging. Five treatments; steaming inside, steaming both sides, steaming and 1% potassium sobate application inside, steaming and potassium sobate application on both sides and control with four replicates were used for the experiment. A simple com type steam injection nozzle was directly connected to a high pressure steam hose. Pots were treated according to the treatments and total colony counts were determined in pots using Ringer solution and cotton swabs for rubbing the surface and milk agar as the culture media. In addition, the Coliform test was also conducted. Mould growth on the packed curd was observed visually and pH of curd was also measured during storage. The cost analysis was also done to evaluate the feasibility of the new technique and compare with the present method. According to the results, steam blast sterilization significantly reduced (P>0.05) the microbial counts compared to the current method. Further, the combination of steam blasting and application of 1% potassium sobate on the inner surface was found to be the best treatment. The shelf life of curd could be extended by four days up to 11 days while reducing the cost to a half.