3D printed functional cookies fortified with Arthrospira platensis: Evaluation of its antioxidant potential and physical-chemical characterization

Highlights

• Antioxidant extraction from the microalga A. platensis was optimised using DoE.

• Edible inks were made using encapsulated microalgae extracts and food hydrocolloids.

• All cookie dough formulations (edible inks) were suitable for 3D food printing.

• 3D printed cookies exhibited colour, texture and microbiological stability over time.

• Extract encapsulation improved cookies antioxidant potential and colour stability.

Abstract

In the last few decades, consumers' growing attention to the close relationship between health and nutrition is emerging as a new trend, mostly regarding the incorporation of natural ingredients into food. Among those ingredients, microalgae are considered as innovative and promising compounds, rich in valuable nutrients and bioactive molecules. In the present work, 3D printed cookies were fortified with the microalga Arthrospira platensis aiming at developing a new functional food with antioxidant properties. A. platensis antioxidants were recovered using ultrasound-assisted extraction in hydroalcoholic solutions. Ethanol/water and biomass/solvent ratios were optimised through a Design of Experiments (DOE) approach, using the antioxidant activity (ORAC and ABTS) and total phenolic content (TPC) as response variables. The highest ORAC, ABTS and TPC values were observed in the extract obtained with 0% ethanol and 2.0% biomass; thus, this extract was chosen to be incorporated into a printable cookie dough. Three different incorporation approaches were followed: (1) dried biomass, (2) freeze-dried antioxidant extract and (3) antioxidant extract encapsulated into alginate microbeads to enhance the stability to heat, light, and oxygen during baking and further storage. All dough formulations presented shape fidelity with the 3D model. The cookies had a_w values low enough to be microbiologically stable, and the texture remained constant after 30 days of storage. Moreover, the extract encapsulation promoted an improvement in the ORAC value and colour stability when compared to all other formulations, revealing the potential of A. platensis for the development of a functional 3D food-ink.

Introduction

Many nutrition concepts have changed during the past few decades, and the food industry has made a significant effort to follow them and adapt their products to these changes. Traditionally, the primary role of diet was to provide enough nutrients to meet metabolic requirements while giving consumers a feeling of satisfaction and well-being. Nowadays, however, it is established that beyond meeting nutritional needs, the diet may modulate various bodily functions and may play detrimental or beneficial roles in some diseases (Bigliardi & Galati, 2013; Roberfroid, 2000). In this regard, it is possible to observe an increasing consumer's health consciousness and demand for healthy foods - facts that are stimulating innovation and new product development in the food industry. This trend is also responsible for an ever-increasing worldwide interest in functional food, which also can be explained by the increasing cost of the health care and the steady boost of life expectancy (Betoret, Betoret, Vidal, & Fito, 2011; Lopez-Rubio, Gavara, & Lagaron, 2006; Plaza, Herrero, Cifuentes, & Ibánez, 2009; Sun, Zhou, Yan, Huang, & Lin-ya, 2018).

Functional food is a natural or processed food that contains known biologically-active compounds which, when in defined quantitative and qualitative amounts, provide a clinically proven and documented health benefit; and, hence, a useful tool for the prevention, management and treatment of diseases. There is a wide range of compounds that have already been incorporated into functional foods, with particular attention being given to ingredients from natural resources (Day, Seymour, Pitts, Konczak, & Lundin, 2009; Herrero, Martín-Álvarez, Senoráns, Cifuentes, & Ibánez, 2005).

Microalgae can be considered an innovative and promising food ingredient, rich in nutrients such as high-value proteins, long-chain polyunsaturated fatty acids, carotenoids, vitamins, minerals, and phenolic compounds, as well as other bioactive molecules (Gouveia, Marques, Sousa, Moura, & Bandarra, 2010). Among them, Arthrospira platensis is one of the main species exploited by the food and nutrition industries, being traditionally used as food by different cultures. This microorganism is a blue-green filamentous prokaryotic cyanobacterium well known for its unique composition, comprising not only up to 70% of protein containing all the essential amino acids, but also polysaccharides, vitamin B₁₂, C, E, and γ-linolenic acid (GLA). Furthermore, it is a source of potent antioxidants, such as carotenoids, polyphenols and phycobiliproteins -a group of photosynthetic pigments majority represented by C-phycocyanin, which are related to numerous reported pharmacological properties; including anticancer, antidiabetes, hepatoprotective and anti-inflammatory (Czerwonka et al., 2018; Da Silva, Fernandes, Barros, Fernandes, & José, 2019; Hu, Fan, Qi, & Zhang, 2019; Plaza, Herrero, Cifuentes, & Ibáñez, 2009; Soni, Sudhakar, & Rana, 2017).

The incorporation of microalgae biomass into traditional foods (e.g. breakfast cereals, bread, pasta, cookies, gelled desserts, and beverages), which are primarily consumed on a daily basis, has been researched and several products have already been launched in the market (Gouveia et al., 2010; Lafarga, 2019). In particular, cookies are considered a convenient dense snack food, offering a valuable supplementation vehicle for nutritional improvement as they are widely accepted and consumed by all age groups. There is a trend for research and innovation in this market segment, which promotes the inclusion of healthy ingredients into cookies, such as antioxidants, vitamins, minerals, proteins and fibers (Batista et al., 2017; Nogueira & Steel, 2018; Šaponjac et al., 2016).

Besides the change in consumer's attitudes towards a healthier diet, it is noteworthy that food ingredients and their nutritional needs vary among individuals, especially children, elderly and athletes (Tan, Toh, Wong, & Li, 2018). This context motivates a growing market for personalized healthy nutrition, which aims to tailor food and diets specifically based on an individual's health condition. In light of this, three dimensional (3D) food printing has gained increasing attention for its distinctive potential to create complex geometric structures, enabling mass customisation while having economic and environmental benefits. The main advantage of this emerging technology is being able to personalize food by tailoring nutrition in a novel multi-flavoured, coloured and textured structure, allowing the incorporation of a broad range of ingredients (Dankar, Haddarah, Omar, Sepulcre, & Pujolà, 2018; Liu et al., 2018a; Pérez, Nykvist, Brøgger, Larsena, & Falkeborg, 2019; Sun et al., 2018).

Considering the above mentioned, this study aimed at developing 3D printed functional cookies fortified with antioxidants extracted from A. platensis, to create a new functional food based on an innovative 3D food-ink. Due to the inherent instability of C-phycocyanin, carotenoids and other antioxidant compounds present in this microalga, the encapsulation of its extract in alginate microbeads was proposed as a way of improving the cookies stability to heat, light, and oxygen during the baking and further storage. Parameters such as colour, texture, water activity and antioxidant potential were investigated and compared with the freeze-dried extract and whole biomass incorporation into the cookie dough.