Design and performance of ohmic-based fermentor model for controlling fermentation process

Abstract

Traditional fermentation process usually takes a long time and hard to achieve and maintain the optimum temperatures condition. The controlled fermentation process can be done using a fermentor for conditioning the temperature at the beginning of the process as bacteria and yeast can develop optimally at certain temperatures. However, traditional heaters that utilize heat transfer by conduction and convection have not been able to homogenize the temperature of products so that the fermentation process is not well controlled. Heating technology that has great potential to produce fast and uniform heating is by using ohmic technology. This research aims to design and to conduct a test of ohmic-based fermentor model. Methods used in this study were a functional and structural analysis of fermentor design and performance test of the fermentor model. The test was conducted using two materials as the heated product (0.02 M NaCl solution as a liquid product and soybean as a non-liquid product) with three variations of voltage treatment (110, 165, and 220 V). Design of the ohmic-based fermentor model had been constructed and tested. Analysis of alternative methods, types, and ohmic fermentor material has been carried out as a reference in designing. Test results showed that the fermentor had been proven to be able to maintain, control, and monitor the temperature in the reactor in real-time. The energy efficiency achieved a high value of 81.96% up to 86.29%. The temperature distribution in the fermentor was also determined uniform for both liquid and non-liquid products with the average value of 40.01±0.16°C (the reference temperature is 40°C). It was indicated that the fermentor model can be used for further fermentation test using various products.

Ohmic Heating: A Review and Application in Food Industry

“…Recently the use of ohmic technology has also begun to be applied to the fermentation on cocoa products and on arabica coffee products to reduce the acidity of coffee beans [31]. During fermentation the temperature used is different based on the optimum temperature of the microorganism.…”

Recent studies and prospective application of ohmic heating for fermentation process: a mini-review

“…The heating rate can be calculated by using equation 2. Then, the amount of heat received by the heated material can be calculated using equation 3 [5,20]. Where, is heating rate (°C/s), Tf is the final temperature (°C), Ti is initial temperature (°C), Δt is heating time (s), Q is heat energy received (J), m is sample mass heated (kg), and cp is specific heat of the heated sample (J.kg -1 °C -1 ).…”

“…Due to the dangers of electricity transmission, materials that can transmit electricity are not permitted to be used in the chamber material for ohmic heating.Plastic, ceramic, glass or something similar (isolator) that cannot transmit electricity is strongly recommended for the ohmic container [5]. In food products, plastics made of polypropylene (PP) are ideal (for low-temperature application) or ceramic/glass material (for high-temperature application).…”

“…The additional feature that must be embedded in ohmic heating equipment is a control system. This feature has the function to control the temperature and electric current [5]. Several researchers have tested that the increase in product temperature increases the electrical current due to the change of electrical conductivity in the product [12,21,23].…”

“…However, a warming generator still uses a conventional heater that utilize heat transmission by conduction and convection. This type of heater has not been able to homogenize the temperature of the products, resulting in a poorly regulated fermentation process [5].…”