3:00 pm - 4:00 pm
3-18J Agricultural/Forestry Centre, University of Alberta, Edmonton AB
Event details: A graduate exam seminar is a presentation of the student’s final research project for their degree.
This is an ALES MSc Final Exam Seminar by Yuliya (Julia) Barsukova. This seminar is open to the general public to attend.
MSc with Drs. John Wolodko and Roopesh Syamaladevi.
Thesis Topic: Inactivation of Salmonella enterica in 3D Printed Ready-to-eat Pudding
Three-dimensional (3D) food printing is a rapidly developing technology, that transforms digital data as input to create a 3D edible physical product as output. It has the potential to change the food industry by offering highly customizable nutritional profiles and designs, while reducing food waste and the cost of manufacturing. The most widespread 3D printing method is extrusion-based, and it requires ingredients fluid enough to be extruded and viscous enough to hold their shape after deposition. As a result, many of these ingredients have high moisture contents and some are meant to be consumed immediately after preparation as ready-to-eat products. Microbial food safety is an important consideration for high moisture ready-to-eat 3D printed food products. Despite the technological advancements in 3D food printing, the microbial safety aspect of 3D printed foods has not been fully investigated.
In this study, the inactivation rate of Salmonella enterica serovar Typhimurium in a printed 3D square made of pudding was assessed. Before and during printing, the pudding was heated at selected time-temperature combinations in a plastic syringe inside a 3D food printer. The temperature profiles evaluated at the center point of the syringe were A (56.9°C), B (60.3°C), C (63.3°C) and D (66.7°C) and the combined heating and printing times were 10, 20, 30 and 40 min. Inactivation of Salmonella increased with temperature and heating time, with the highest reduction of >7 log CFU/g after 40 min at temperature profiles C and D. The inactivation of Salmonella after 10 min treatment at all the temperatures was not significantly different, and the 40 min heat treatment at profile B was not significantly different from profiles C and D after 30 min heat treatment.
The second part of this study focused on the simulation of the heating of pudding in the plastic extrusion syringe inside the 3D printer by finite element modeling, using axisymmetric 2D model. The experimental time-temperature relationships at the selected locations of the syringe including at the center and the gap between the syringe and the 3D printer’s stainless-steel barrel during the heating of pudding were compared with mathematical simulation results. There was no considerable difference in the heating profiles of syringe quarter points, however, the contour plots showed heat loss due to convection at the top of the syringe. Overall, the predicted temperature changes were in good agreement with the experimental values. These results indicate the potential of finite element analysis to be used in conjunction with 3DFP as a useful tool for analyzing heat transfer and distribution in a closed system.