Design of Food Process Controls Systems

Author(s):  
Mark T. Morgan ◽  
Timothy A. Haley
2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Erin K. McMurtrie ◽  
Suzanne D. Johanningsmeier

Commercial cucumber fermentation produces large volumes of salty wastewater. This study evaluated the quality of fermented cucumbers produced commercially using an alternative calcium chloride (CaCl2) brining process. Fermentation conducted in calcium brines (0.1 M CaCl2, 6 mM potassium sorbate, equilibrated) with a starter culture was compared to standard industrial fermentation. Production variables included commercial processor(n=6), seasonal variation (June–September, 2 years), vessel size (10,000–40,000 L), cucumber size (2.7–5.1 cm diameter), and bulk storage time (55–280 days). Cucumber mesocarp firmness, color, bloater defects, pH, and organic acids were measured. Complete lactic acid fermentation was achieved, resulting in terminal fermentation pH values of 3.23 ± 0.09 and 3.30 ± 0.12 for CaCl2and NaCl processes, respectively. On average, CaCl2brined, fermented cucumbers were 1.8 N less firm, which remained significant in the finished product(P<0.0001). Color differences evidenced by higher hue and lower chroma values(P<0.0269)were consistent with increased photooxidation in CaCl2brined cucumbers. Commercial implementation of CaCl2brines for cucumber fermentation in open tanks variably resulted in texture and color defects that can impact product quality. Additional research is needed to understand the atypical softening observed at the commercial scale and identify process controls for quality improvements.


Author(s):  
Eniko T. Enikov ◽  
Estelle Eke

Teaching classical controls systems design to mechanical engineering students presents unique challenges. While most mechanical engineering programs prepare students to be well-versed in the application of physical principles and modeling aspects of physical systems, implementation of closed loop control and system-level analysis is lagging. It is not uncommon that students report difficulty in conceptualizing even common controls systems terms such as steady-state error and disturbance rejection. Typically, most courses focus on the theoretical analysis and modeling, but students are left asking the questions…How do I implement a phase-lead compensator? …What is a non-minimum phase system? This paper presents an innovative approach in teaching control systems design course based on the use of a low-cost apparatus that has the ability to directly communicate with MATLAB and its Simulink toolbox, allowing students to drag-and-drop controllers and immediately test their effect on the response of the physical plant. The setup consists of a DC micro-motor driving a propeller attached to a carbon-fiber rod. The angular displacement of the rod is measured with an analog potentiometer, which acts as the pivot point for the carbon fiber rod. The miniature circuit board is powered by the USB port of a laptop and communicates to the host computer using the a virtual COM port. MATLAB/Simulink communicates to the board using its serial port read/write blocks to command the motor and detect the deflection angle. This presentation describes a typical semester-long experimental protocol facilitated by the low-cost kit. The kit allows demonstration of classical PID, phase lead and lag controllers, as well as non-linear feedback linearization techniques. Comparison between student gains before and after the introduction of the mechatronic kits are also provided.


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