Phycocyanin (PC) is commercially exploited in various commercial sectors, as novel applications are developed rapidly. However, the state-of-the-art is difficult to define, given the extremely heterogeneous information available. Hence, this study aimed to perform a technological and scientific review on PC production from Spirulina (Arthrospira spp.), based on a bibliometric analysis of patents and research articles deposited from 2015 to 2023. To close the knowledge gap evidenced by the prospection, we optimized the instrumental conditions of microalgae cultivation, i.e., orbital agitation, culture volume, and cultivation time, for the production of PC. We assessed the color parameters and stability of the PC used as an ice cream colorant. The prospection highlighted rather diverse points of view between academia and the industry regarding PC production methods. The optimization showed a substantial impact of cultivation time on PC yield and purity. A purification step via precipitation was note necessary to obtain food-grade PC (purity > 0.7). Optimal experimental conditions were 180 rpm, 250 mL, and 14 days of cultivation. The ice cream colored using PC from the optimized cultivation conditions showed concentration-dependent color variations, without significant color losses for 90 days.

Currently, all feed and food come from plant- or animal-based production systems. The potential of the natural biodiversity of microorganisms for the highly efficient production of nutrients has yet to be leveraged. We present an overarching concept that ranges from the development of a national collection of regional microalgae to the decentralised production of nutrient-rich biomass for animal feed production. The focus is on the substitution of classic plant-based feed to reduce competition for arable land, to increase the nutritive value of animal-based food, and to reduce methane emissions from ruminants. The photoautotrophic and mixotrophic cultivation of microalgae are well aligned with the goals of CO2 fixation and the later contribution to the valorisation of side streams from the food industry. We also present the initial results on strain adaptation to diverse cultivation conditions.

The efficiency and outcomes of mechanically disrupting microalgal cell walls depend on various factors and are case-specific. In general, bead milling is reproducible and scalable, and it can successfully increase the digestibility of microalgal biomass. However, its effects on the aroma of microalgal biomass have not yet been assessed. This study is the first to report the use of the NanoWitt-100 bead mill to break down microalgal biomass. Optimization of processing time and cell concentration revealed that the optimal conditions were a milling time of 15 min, and a cell concentration of 50 g L ⁻¹ . Under these conditions, we then compared the in vitro protein and amino acid digestibility as well as volatile organic compound (VOC) profiles of undisrupted and disrupted samples. Bead milling substantially increased total protein digestibility from 62.2 ± 2.28 to 99.7 ± 0.06%. The digestibilities of all amino acids and the in vitro digestible indispensable amino acid scores (DIAAS) also increased. Although the release of VOCs increased in the disrupted biomass, the VOC profiles indicated an improvement in the final aroma of the biomass. This outcome was due to a reduction in acid concentration and an increase in ester concentration as a proportion of the total VOCs. Overall, these findings support further scalability tests, sensory analysis, and in vivo trials using microalgae disrupted with the bead mill NanoWitt-100.

Microalgae have been proposed for the bioremediation of wastewater, as well as for biofertilization and biostimulation of several plant species. This study used Limnospira sp. biomass produced in brewery wastewater to formulate a pelletized biofertilizer. Its efficacy in promoting barley (Hordeum vulgare) growth was then compared with chemical fertilizers and a control group without fertilization on lab- and pilot-scale setups. On a 100-day lab-scale experiment under controlled light (260–280 µmol photons m⁻² s⁻¹) and temperature (20 ± 2 °C), minor differences in plant growth were observed, whereas the elemental composition of the barley plants did not differ, including toxic elements. On a pilot-scale agricultural setup (5 m²) under environmental conditions, barley productivity, protein content, and the percentage of class I grains (diameter ≥ 2.5 mm) significantly increased based on the different dressing techniques used (p < 0.05). Using the microalgae-based biofertilizer for both base and top dressing increased productivity, protein content, and grain size (% class I) by 26.9%, 14.4%, and 8.78%, respectively, compared to using chemical fertilizers (NPK 5:20:20 and urea). These results indicate the great potential of using microalgae biomass from wastewater treatment as biofertilizer for more sustainable agriculture.