Influence of ultrasonic and peracetic acid incorporation on microbiological and physicochemical properties of sweet potato (Ipomoea batatas L.)

Sweet potato (Ipomoea batatas L.) has a low glycemic index by low digestibility of the starch Therefore it is very appropriate for diabetic or obesity people. During harvesting, sweet potato tuber is normally contaminated by dust, soil and microorganism. It also has high respiration rate and perishability. Keeping the original tuber without water cleaning in dry cool place can store it for a nearly one month. In case of washing sweet potato tuber to prevent cross-contamination, it can lead to decay or rotten. With the purpose of preservation for the clean tuber in a long period of time, it can be washed in water under bubble blowing with ultrasonic and peracetic acid. Sweet potato tuber was primarily infected E. Coli, Salmonella, Staphylococcus, Listeria strains at 0.1 % to obtain 8.5 log CFU/g. Experiments examined the impact of ultrasonic cavitation at 37 kHz and 50 W at 12 degrees C in different period intervals (2.0 divided by 4.0 minutes), various concentration of peracetic acid (0 divided by 30 ppm) on the survival of these inoculated microbial strains as well as physicochemical properties such as firmness, carotenoid, total phenolic content, total flavonoid content on the control and treated sweet potato. Results showed that ultrasonic at 37 kHz, 50 W at 12 degrees C in 3.5 minutes combined peracetic acid at 15 ppm successfully retarded the pathogen density, effectively maintained physicochemical attributes of sweet potato. Ultrasound and peracetic acid incorporation greatly improved spoilage and pathogenic microorganisms sterilization while maintaining the physicochemical quality attributes in sweet potato with respect to individual treatments.