Impact of Pressurized Liquid Extraction and pH on Protein Yield, Changes in Molecular Size Distribution and Antioxidant Compounds Recovery from Spirulina.

Jianjun Zhou,Houda Berrada,Mladen Brncic,Francisco J Barba,Zhenzhou Zhu,Celia Carrillo,Min Wang

doi:10.3390/foods10092153

Abstract

The research aims to extract nutrients and bioactive compounds from spirulina using a non-toxic, environmentally friendly and efficient method—Pressurized Liquid Extraction (PLE). In this work, Response Surface Methodology (RSM)–Central Composite Design (CCD) was used to evaluate and optimize the extraction time (5–15 min), temperature (20–60 °C) and pH (4–10) during PLE extraction (103.4 bars). The multi-factor optimization results of the RSM-CCD showed that under the pressure of 103.4 bars, the optimal conditions to recover the highest content of bioactive compounds were 10 min, 40 °C and pH 4. Furthermore, the compounds and antioxidant capacity of PLE and non-pressurized extraction extracts were compared. The results showed that under the optimal extraction conditions (10 min, 40 °C and pH 4), PLE significantly improved the antioxidant capacity (2870.5 ± 153.6 µM TE), protein yield (46.8 ± 3.1%), chlorophyll a (1.46 ± 0.04 mg/g), carotenoids (0.12 ± 0.01 mg/g), total polyphenols (11.49 ± 0.04 mg/g) and carbohydrates content (78.42 ± 1.40 mg/g) of the extracts compared with non-pressurized extraction (p < 0.05). The protein molecular distribution of the extracts was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and the results showed that there were more small-molecule proteins in PLE extracts. Moreover, Liquid Chromatography Triple Time of Flight Mass Spectrometry (TOF–LC–MS–MS) was used to analyze the phenolic profile of the extracts, and the results showed the extracts were rich on phenolic compounds, such as p-coumaric acid and cinnamic acid being the predominant phenolic compounds in the PLE extract. This indicates that PLE can promote the extraction of bioactive compounds from Spirulina, which is of great significance for the application of PLE technology to obtain active substances from marine algae resources.

Highlights

Functional foods are generally foods rich in ingredients that can provide or promote specific beneficial effects for human health
The results showed that using ethanol as the extraction reagent, samples with higher antioxidant capacity can be obtained at 170 ◦ C and 15 min
The results obtained from this study showed that spirulina is a relevant source of nutriThe results obtained from this study showed that spirulina is a relevant source of ents and bioactive compounds with antioxidant capacity, but the recovery of these valuable nutrients and bioactive compounds with antioxidant capacity, but the recovery of these constituents was greatly influenced valuable constituents was greatly by the extraction conditions explored in this study

Summary

Introduction

Functional foods are generally foods rich in ingredients that can provide or promote specific beneficial effects for human health. These ingredients, such as proteins, lipids, vitamins and trace elements, can be derived from microalgae [1,2]. There are more than 1000 kinds of algae in the ocean, and they are used as an important food source in many countries, such as China, Japan and South Korea. Among the numerous species of algae, spirulina (Arthrospira platensis), a cyanobacteria, has been extensively studied due to its commercial importance as a source of proteins, vitamins and fatty acids [5]. The main problem in practical industrial applications is how to use green, highly efficient and low-cost extraction methods to make the bioactive compounds of spirulina useful in the industry

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Conclusion