9:00 am - 10:00 am
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 Khemiga (Gaam) Khemacheevakul. This seminar is open to the general public to attend.
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Meeting ID: 960 1874 6087
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Thesis Topic: Manufacture & Characterization of 3D-Printed Sugar-Reduced Chocolates and their Sensory Perception
MSc with Drs. Wendy Wismer and John Wolodko
High global sugar consumption exceeding recommendations and an increased awareness of health concerns associated with excess sugar consumption have promoted the development of sugar-reduced foods by manufacturers, and consumption of sugar-reduced foods by consumers. As confectionary items are a major contributor to total sugars intake, sugar-reduction strategies should focus on this group of foods. 3D food printing (3DFP) is an emerging area of research, and previous studies have investigated single-extruder 3D printers, with a focus on optimizing material formulation and 3D printing parameters. However, few have addressed sensory perception of the printed foods, and none have utilized 3DFP for sugar-reduction. Furthermore, novel methods to optimize 3DFP can be developed as there are several ways to define a ‘good’ print. Therefore, this research comprises two studies that aimed to demonstrate the capability of a dual-extruder 3D food printer as an innovative tool to manufacture sugar-reduced 3D printed chocolates with desirable sensory qualities.
In the first study, six variations of a three-layered hollow cylinder (diameter 28.00 mm, height 10.80 mm, wall thickness 4.37 mm) were designed in computer-aided-design software. Each variation had different layering orders of H or L chocolate to create chocolates with different total % sugar concentrations. A four-step procedure was used to optimize 3D printing parameters for a dual-extruder 3D printer. 3D printer speed and flow rate settings were first quantified. Then, chocolate lines that were 3D printed at varying print speed and flow rate were assessed by qualitative criteria to determine optimal print settings. Then, printed product accuracy and precision was validated by comparing measured mass and dimensions of 3D chocolate prints to digital designs. Finally, 3D printed chocolate quality was evaluated by determining chocolate melting properties prior to and after 3D printing. The optimal print setting for both extruders was identified as print speed 35 (2.92-2.94 mm/s) and flow rate 100 (6.11-6.55 mm3/s) as it manufactured 3D printed chocolates with no qualitative defects and with similar mass and dimensions compared to the digital designs. The six designs had mean total % sugar (g sugar/g chocolate) of 51.5%, 41.6%, 41.6%, 34.9%, 34.0%, and 26.7%. Melting properties suggested that a printing temperature between 28-30℃ was suitable for both chocolates, as the chocolates remained tempered after 3D printing at these temperatures.
In the second study, the temporal sensory profile, perceived sweetness intensity, and acceptance of the six manufactured sugar-reduced and non-sugar reduced 3D printed chocolates were investigated. The chocolate with 51.5% total sugar (printed with only H chocolate) was used as a high sugar control. A consumer panel (n=72) completed a temporal dominance of sensations (TDS) evaluation, rated overall sweetness intensity on a 5-point scale (1=not at all sweet, 5=extremely sweet), and rated liking on a 9-point hedonic scale (1=dislike extremely, 9=like extremely). 3D printed chocolates with 19% sugar reduction were perceived as similarly sweet compared to the high sugar control, while samples with 32% sugar reduction were perceived as less sweet. Layering order of H and L chocolates changed the temporal sensory attribute profile of the 3D printed chocolates, which influenced perceived overall sweetness. A sugar concentration gradient between layers improved the sweetness enhancement effect. All the manufactured 3D printed chocolates were similarly well-liked.