Exploring and strengthening the potential of R-phycocyanin from Nori flakes as a food colourant

Spotlight on the long-term effects of micro/nanoplastics exposure on Spirulina platensis: Algal cells, extracellular polymeric substances, and phycocyanin

Spirulina platensis (SP) provides humans with proteins and natural pigments. The effects of micro/nanoplastics (MNPs) on SP are of great interest. We focused on the effects of high concentrations (100-300 mg/L) of polystyrene MNPs on SP for 50 days. MNPs caused growth retardation, a decrease in peak concentration of algal cells, the emergence of surface cracks and pores, and stimulated the secretion of extracellular polymeric substances that promoted heterogeneous aggregation of SP. During the first 35 days, there were significant differences between the exposure groups in the phycocyanin concentration, yield and purity and the ratio of phycocyanin to phycobiliprotein, with the higher MNPs concentration resulting in lower values, whereas on day 50 there were no statistically significant differences in any of these metrics between the control or exposure groups. This study enriches the knowledge about the long-term effects of MNPs on SP for microalgae culture and food industry.

Comparison of Pressurized Water Extraction With Ultrasound Assisted Extraction for Isolation of Phycobiliproteins From Arthrospira platensis (Spirulina)

INTRODUCTION

Cyanobacterium Arthrospira platensis (AP) (Nordstedt) Gomont contains high content of phycobiliproteins (PBP), which are an important source for food industry. Methods effectively extracting proteins contained in AP cells are demanded to provide a supply of the material. Water-based extraction methods are advisable due to the high solubility of the PBP.

OBJECTIVES

Extraction techniques such as ultrasound assisted extraction (UAE) and pressurized water extraction (PWE) are popular due to their environmental friendliness, better extraction efficiency, and faster extraction process. In this paper, efficiency of the two methods is compared.

MATERIALS AND METHODS

PWE along with UAE is utilized for release of PBP from the AP cells. The extraction parameters including time, temperature, pressure, and ultrasound intensity are tested to obtain the most efficient setup. The methods were evaluated using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and the replicates of PWE extracts were further analyzed by capillary isoelectric focusing with laser-induced fluorescence (cIEF-LIF).

RESULTS

The developed PWE method using higher pressure treatment at lower temperature was significantly faster than UAE methods, and the SDS-PAGE results showed a high content of phycobiliproteins in the extracts. cIEF-LIF analysis showed that the sequential PWE of individual samples was repeatable, and the mild extraction provided a fluorescent profile similar to the commercially available C-phycocyanin standard.

CONCLUSION

Pressurized water extraction was shown to be an efficient, rapid, and well-automated extraction method for AP proteins in general, including bioactive phycobiliproteins. Obtained results encourage the use of PWE in small-scale analytical applications for primary extraction of proteins.

Enhancing the stability and functionality of phycobiliproteins as natural food colourants through microparticle formulation

The food industry is increasingly turning to microalgae pigments as natural functional colourants to replace potentially harmful synthetic dyes. Among those, phycobiliproteins offer deep and vibrant colours with bioactivities, showing to be a promising alternative. However, incorporating them into a food matrix can be challenging due to their inherent instability, low bioavailability, and off-flavours. Accordingly, the present work aimed to prepare microparticles of phycocyanin (PCMP) and of an ultrasound-assisted phycoerythrin-rich extract from Porphyridium purpureum (PEMP) to improve these natural colourants' stability and functional properties. The microparticles were prepared by Nano spray-drying using inulin and gum Arabic as coating materials, resulting in particles with high yield, encapsulation efficiency (from 69 % to 80 %), solubility, and colour retention. Combining inulin and gum Arabic allowed the formation of smaller and more homogeneous particles with increased antioxidant potential when compared to using inulin alone. Moreover, gum Arabic improved the bioaccessibility of PEMP from 35 % to 51 %, demonstrating the potential of this microparticle formulation to enhance the stability and functionality of phycobiliproteins.

Probing the structural stability of R-phycocyanin under pressure

The red macroalgae Porphyra, commonly known as Nori, is widely used as food around the world due to its high nutrient content, including the significant abundance of colored phycobiliproteins (PBPs). Among these, R-phycocyanin (R-PC) stands out for its vibrant purple color and numerous bioactive properties, making it a valuable protein for the food industry. However, R-PC's limited thermal stability necessitates alternative processing methods to preserve its color and bioactive properties. Our study aimed to investigate the in-situ stability of oligomeric R-PC under high pressure (HP) conditions (up to 4000 bar) using a combination of absorption, fluorescence, and small-angle X-ray scattering (SAXS) techniques. The unfolding of R-PC is a multiphase process. Initially, low pressure induces conformational changes in the R-PC oligomeric form (trimers). As pressure increases above 1600 bar, these trimers dissociate into monomers, and at pressures above 3000 bar, the subunits begin to unfold. When returned to atmospheric pressure, R-PC partially refolds, retaining 50% of its original color absorbance. In contrast, heat treatment causes irreversible and detrimental effects on R-PC color, highlighting the advantages of HP treatment in preserving both the color and bioactive properties of R-PC compared to heat treatment.

A comprehensive review on novel synthetic foods: Potential risk factors, detection strategies, and processing technologies

Nowadays, the food industry is facing challenges due to the simultaneous rise in global warming, population, and food consumption. As the integration of synthetic biology and food science, novel synthetic foods have obtained high attention to address these issues. However, these novel foods may cause potential risks related to human health. Four types of novel synthetic foods, including plant-based foods, cultured meat, fermented foods, and microalgae-based foods, were reviewed in the study. The original food sources, consumer acceptance, advantages and disadvantages of these foods were discussed. Furthermore, potential risk factors, such as nutritional, biological, and chemical risk factors, associated with these foods were described and analyzed. Additionally, the current detection methods (e.g., enzyme-linked immunosorbent assay, biosensors, chromatography, polymerase chain reaction, isothermal amplification, and microfluidic technology) and processing technologies (e.g., microwave treatment, ohmic heating, steam explosion, high hydrostatic pressure, ultrasound, cold plasma, and supercritical carbon dioxide) were reviewed and discussed critically. Nonetheless, it is crucial to continue innovating and developing new detection and processing technologies to effectively evaluate these novel synthetic foods and ensure their safety. Finally, approaches to enhance the quality of these foods were briefly presented. It will provide insights into the development and management of novel synthetic foods for food industry.

Narrative Review of the Current and Future Perspectives of Phycobiliproteins' Applications in the Food Industry: From Natural Colors to Alternative Proteins

Vivid-colored phycobiliproteins (PBPs) have emerging potential as food colors and alternative proteins in the food industry. However, enhancing their application potential requires increasing stability, cost-effective purification processes, and consumer acceptance. This narrative review aimed to highlight information regarding the critical aspects of PBP research that is needed to improve their food industry potential, such as stability, food fortification, development of new PBP-based food products, and cost-effective production. The main results of the literature review show that polysaccharide and protein-based encapsulations significantly improve PBPs' stability. Additionally, while many studies have investigated the ability of PBPs to enhance the techno-functional properties, like viscosity, emulsifying and stabilizing activity, texture, rheology, etc., of widely used food products, highly concentrated PBP food products are still rare. Therefore, much effort should be invested in improving the stability, yield, and sensory characteristics of the PBP-fortified food due to the resulting unpleasant sensory characteristics. Considering that most studies focus on the C-phycocyanin from Spirulina, future studies should concentrate on less explored PBPs from red macroalgae due to their much higher production potential, a critical factor for positioning PBPs as alternative proteins.

Stability and bioactivities evaluation of analytical grade C-phycocyanin during the storage of Spirulina platensis powder

C-phycocyanin (C-PC) is a natural high-value blue phycobiliprotein from Spirulina platensis, which has wide biological applications in food, pharmaceutical, and cosmetics. However, the freshness of S. platensis powder (SPP) materials and C-PC purification play critical roles in evaluating the stability and bioactivities of C-PC, which severely affect its commercial application. This study investigated the effect of spray-dried SPP freshness on the biofunctional activities of analytical grade C-PC (AGC-PC). The yield of AGC-PC extracted from spray-dried SPP could reach 101.88 mg/g (75% recovery ratio) after purification by reversed phase high-performance liquid chromatography (RP-HPLC) system. The half-life period (t1/2 ) of AGC-PC stability at 60°C and 8000 lux light could remain 171.70 min and 176.11 h within 6 months storage of spray-dried SPP. The emulsifying activity index (EAI) and foaming capacity (FC) of AGC-PC from fresh-dried SPP showed maximum values of 68.64 m2 /g and 252.9%, respectively. The EC50 of AGC-PC from fresh spray-dried SPP on 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzothiazoline -6-sulfonic acid (ABTS+·) scavenging activity could reach 63.76 and 92.93 mg/L, respectively. The EC50 of AGC-PC from fresh spray-dried SPP on proteinase inhibition and anti-lipoxygenase activity were 302.96 and 178.8 mg/L, respectively. The stability and biofunctional activities of AGC-PC remained stable within 6 months storage of SPP, and then rapidly decreased after 9 months storage due to the disintegration of the trimeric (αβ)3 and hexameric (αβ)6 forms of C-PC. It is concluded that the optimal storage period of SPP for preparation of AGC-PC in commercial use should be less than 6 months. PRACTICAL APPLICATION: The C-phycocyanin (C-PC) from dried Spirulina platensis powder (SPP) has been widely applied in food nutritional, florescent markers, pharmaceuticals, cosmetics, etc, due to its blue color, fluorescence, and antioxidant properties. However, the effect of dried SPP freshness on the stability and functional activity of C-PC has been rarely reported. This study found that the thermostability, photostability, emulsifying, antioxidant, and anti-inflammatory activities of analytical grade C-PC (AGC-PC) significantly decreased after 6 months storage of SPP. Based on investigations, we have proposed that the suitable storage time of dried SPP for preparation of AGC-PC in commercial application should be within 6 months.