Optimization of Concentrate Production from the Microalga Nannochloropsis oceanica
Author: Cynthia Maria Oliveira Couto (Currículo Lattes)
Advisor: Dr. Dariano Krummenauer
Abstract
This thesis aimed to optimize the production of concentrates from the microalga Nannochloropsis oceanica. The work was divided into three chapters. In the first chapter, the influence of bacterial presence and organic matter on the formation of dimethyl sulfide (DMS) during the shelf life of the concentrates was assessed. To this end, the shelf life of two types of concentrates—one control and one that underwent a washing process—was evaluated at two storage temperatures (24 °C and −4 °C). The washing process significantly extended the shelf life of the concentrate from 17 to 85 days at −4 °C. The second chapter compared the use of a skimmer and a washing process as strategies to reduce bacterial density in the concentrates over time. Five treatments were tested: a control, individual application of the skimmer and washing process, a combination of both, and a variation of the washing procedure. The best results were obtained from the combination of the two methods (skimmer + washing) and the intensified washing process. The two washing variations showed statistically significant differences. In the third chapter, the washing process was optimized to improve bacterial removal efficiency without affecting cell viability, while also enhancing the cost-benefit ratio to make the process economically feasible. To make the process viable, a 10% increase in the selling price of the concentrate was required. The optimal result was achieved by repeating the process five times at a relative centrifugal force of 3,405 (279 g), at 24 °C for 20 minutes.
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