CSWK and OligoCS obtained from acid/base treatment and enzymatic degradation without the uses of organic solvents or chemical reagents were examined as potential food safety preser- vatives. The treatment of minced pork with OligoCS concentration 0.4% (w/w) brought in 20–30% reduction of LAB, Staphylococcus, Enterobacteriaceae and Salmonella spp. compared to the food with- out any treatment. Furthermore, OligoCS showed a suppression in the BAI values on the second day and retarded both the lipid oxida- tion level and protein oxidation over 7 days of storage at 4 °C. The present work shows how water-based chitosan in nanometer sizes can act as a food preservative for the extension of shelf-life. The main factors are suspected to relate to (i) positively charged chito- san, (ii) the high surface area for effective assessment, and (iii) the efficient reaction between the free amino groups along chitosan and free radicals, including radical scavengers during meat spoil- age to retard the lipid and protein oxidation.