Process for recycling slaughterhouses wastes and by-products by fermentation

Abstract

Slaughterhouse wastes including animal and poultry wastes, were mixed separately with 15% molasses and inoculated with a starter culture of Lactobacillus plantarum. The mixture was incubated at 22–24 °C for 10–15 days. Physico-chemical and chemical determinations including pH, dry matter, ash, Total Nitrogen (TN), Non Protein Nitrogen (NPN), Total Volatile Nitrogen (TVN), lipids and reducing sugars were determined on the products. In parallel, microbiological analyses, including standard plate count, coliforms, Salmonella, Clostridium, were also determined daily. Results indicated that the product obtained from the animal wastes showed low counts of coliforms. Salmonella was not detected. Chemical determinations showed a net decrease of the pH and low levels of total volatile nitrogen with a decrease in total sugars. Non protein nitrogen was high in the product relative to the raw material, while the product obtained from poultry by-products showed very interesting data for both chemical and microbiological characteristics: that is, pH decrease to low levels was rapid and the preservation was ensured by the net decrease in Gram negative bacteria and Clostridium, the absence of Salmonella and the stabilization of the standard plate counts. The product had a high level of fat and crude protein.