Effect of pH on Rhodomonas salina growth, biochemical composition, and taste, produced in semi-large scale under sunlight conditions

Abstract

Rhodomonas salina is a microalgal species, belonging to the cryptophytes, and is widely used as aquaculture feed because of its high nutritional profile and phycoerythrin content. This study investigated the effect of pH on the growth, biochemical composition, and taste of R. salina when cultivated on a semi-large scale under natural light conditions. Two tubular photobioreactors (200 L) were used for the cultivation of R. salina with sunlight as the only illumination source. Two different pH setpoints were applied, 7 and 8.5. Optimal temperature and nutrient conditions were applied, according to previous research findings. The results demonstrated that the productivity of R. salina was higher at pH 7, 0.06–0.14 gdry weight L−1 day−1, compared to pH 8.5, 0.03–0.12 gdry weight L−1 day−1. It was found that protein and total fatty acid concentrations were higher in the biomass that was produced at pH 8.5, 33.7% and 12.3% of dry weight, respectively, while at pH 7, the protein content was 31.9% and the total fatty acids 8.8% of dry weight. The phycoerythrin concentration, like protein, was higher at pH 8.5, 2.7% of dry weight, compared to pH 7, 1% of dry weight. The free amino acid and nucleotide profile of R. salina was affected by the pH, resulting in increased equivalent umami concentration at pH 7. For the sensory evaluation, an expert panel on algae flavors evaluated the effect of pH on the taste of R. salina, reporting that the biomass that was produced at pH 7 had more umami flavor than the biomass that was produced at pH 8.5, which was evaluated as more bitter.

Interspecific Interactions Drive Nonribosomal Peptide Production in Nodularia spumigena

“…1 and Table S3), it is plausible that once the alga became adapted to the higher pH during the lag phase, the growth resumed at the normal rate. In R. salina , a decrease in cell density has been observed at high (>10.5) pH levels ( 19 ), and recently, a growth inhibition at pH 8.5 compared to pH 7 has been demonstrated ( 48 ). In our experiment, however, the pH values never exceeded 8.5, which might explain the adaptation and compensatory growth resulting in no significant change in the AUC values.…”

Review on microalgae protein and its current and future utilisation in the food industry

“…Interestingly, at higher TCO 2 concentrations, the PC decreased, potentially due to insufficient nitrogen and carbon compounds. Latsos et al (2022) examined two distinct pH, namely 7 and 8.5 and observed that the PC reached its highest level (33.7%) at pH 8.5. In contrast, at pH 7, the PC was slightly lower (31.9%).…”

“…Latsos et al . (2022) examined two distinct pH, namely 7 and 8.5 and observed that the PC reached its highest level (33.7%) at pH 8.5. In contrast, at pH 7, the PC was slightly lower (31.9%).…”

The Impact of Non-Concentrated Storage on the Centrifugation Yield of Microchloropsis gaditana: A Pilot-Scale Study

“…A disadvantage of this non-concentrated storage approach is that large volumes of algae cultures must be stored. However, the pre-concentration of algae biomass (to 10-40 g OM/L) via low-shear technologies can offer a solution in this respect [10].…”