EVALUATION, MODELING AND OPTIMIZATION OF THE CLEANING PROCESS OF CONTAMINATED PLASTIC FOOD REFILLABLES

In this study several types of bottle materials (glass, PET (polyethyl ene terephthalate), PC (polycarbonate), HDPE (high density polyethylen e), PP (polypropylene) and PVC (polyvinyl chloride)) were evaluated in order to be used as food refillables, comparing the residual chemical contamination after classical caustic washing. Bottles were contamina ted with model chemicals (chloroxylenol and d-limonene) and caustic wa shed with varied process parameters using a simulated laboratory-scale washing procedure. After washing, the chemical-contaminated bottles w ere filled with water and stored for 28 days at 37 degrees C. The conc entrations of the model chemicals in the water after storage were take n as a measure of chemical contamination. The influence of the cleanin g parameters (temperature, caustic and commercial additive concentrati on) was studied using response surface methodology. Washing temperatur e showed a significant influence on the removal of absorbed chemicals from surfaces compared with the effect of the caustic and especially t he additive concentration. Optimization of caustic cleaning for the cl eaning process in question led to better cleaning effectiveness, altho ugh none of the different washing conditions were able to remove all a bsorbed chemicals out of the polymeric resins. Commercially available plastic refillables (PET and PC) showed the best chemical rinsability. Glass bottles, however, had in every case the best rinsing characteri stics.