Dairy Products through the Addition of Microalgae

Dairy Products through the Addition of Microalgae: History

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Subjects: Food Science & Technology

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Microalgae are prokaryotic or eukaryotic photosynthetic microorganisms which have the ability to grow fast and to live under conditions not favorable to other species. They are attracting increasing attention, as their incorporation in foods and beverages can be a promising strategy to develop sustainable foods with improved nutritional profiles and a strong positive impacts on health. Despite the increasing market demand in plant-based foods, the popularity of fermented dairy foods has increased in the recent years since they are a source of microorganisms with health-promoting effects. In this context, the incorporation of microalgae in cheeses, fermented milks and other dairy products represents an interesting approach towards the development of innovative and added-value hybrid products based on animal proteins and enriched with vegetable origin ingredients recognized as extremely valuable sources of bioactive compounds. Considering the importance of commercialization, regulatory issues about the use of microalgae in dairy products are also discussed.

microalgae
dairy products
bioactive compounds
legislation

1. Introduction

Microalgae are prokaryotic or eukaryotic photosynthetic microorganisms which have the ability to grow fast and to live under conditions not favorable to other species [1]. The biomass of these microorganisms is characterized for being a remarkable source of bioactive compounds and other products, which has led to a huge interest in their use in recent years [2,3]. Although approximately 10 million species of microalgae have been described in nature, so far only 50 of these species (mainly from Arthrospira (Spirulina), Chlorella, Porphyry, Nannochloropsis, Haematococcaceae, and Dunaliella genera) have been studied in detail in relation to their biotechnological use [4,5,6]. The nutritional composition of microalgae is very variable and depends enormously on the species and even within the species, depending on the growth conditions (composition of the medium, temperature and light regime) [7]. Table 1 shows the nutritional composition (protein, fat, carbohydrates, and minerals, among others) of the most studied microalgae species.

Table 1. Physicochemical composition of the most studied species of microalgae.

Physicochemical Composition	Species
	Chlorella vulgaris¹	Nannochloropsis gaditana²	Arthrospira platensis³	Auxenochlorella protothecoides⁴	Euglena gracilis⁵	Dunaliella bardawil⁶	Tetraselmis chuii⁷
Protein (% dry matter)	12–44	18–50	50–70	6–43	41–47	29–31	11–46
Lipid (% dry matter)	22–46	10–17	8–9.3	7–59	13–23	10–19	0.3–23
Carbohydrate (% dry matter)	24–39	15–31	13–48	15–35	34–43	11–12	30–54
Pigments
Lutein (mg/kg)	0.2–5	n.r	n.r	n.r	n.r	4.2–6.7	624
Chlorophyll (mg/L)	6–18	0.3–2.3	5–14	0.1–4	1–5.3	7.9–9.1	353–400
Phycocyanin (mg/mL)	n.r	n.r	0.5–2.3	n.r	n.r	n.r	n.r
Beta-carotene (mg/g)	n.r	0.1–2.9	n.r	0.1–1.1	0.1–52	0.8–1.5	0.1–1
Vitamins (mg/kg)
B2	20–34	25–62	34–81	n.r	n.r	n.r	5.3
B3	0.2–0.3	51–70	0.1–55	n.r	n.r	n.r	80
B9	0.7–1	17–26	2.6–7.9	n.r	n.r	n.r	200
B12	0.3–2.4	0.9–1.7	1.6 –3.2	n.r	n.r	0.42	78–195
E	n.r	n.r	n.r	n.r	0.2–1.6	1.5–2	0.2
C	n.r	n.r	n.r	n.r	0.9–1.3	1.8–2.2	0.8
Fatty acids (% total fatty acids)
C16:0 (palmitic)	20–30	13–41	43–57	11–25	14–16	15–17	19–36
C18:3 n-3 (alpha-linolenic)	22–24	0.9–3	1.3–23	2.4–30	0.1–0.3	22–31	22–28
C18:3 (linolenic)	26–28	0.3–7.4	14–19	22–35	n.r	3.2–3.7	n.r
C16:2 (hexadecadienoic)	12–23	0.1–2	2.2–6	0.4–3.5	1–2.5	12–14	1.8–5
C18:1 (oleic)	29–33	1.6–7.3	1–19	7.6–50	3.7–6.4	5.3–8.9	12.5–20

Information adapted from: ¹ Ran et al. [12]; Mehariya et al. [13]; Rodrigues-Sousa et al. [14]; ² Ran et al. [15]; Fattore et al. [16]; Nogueira et al. [17]; ³ Shanthi et al. [18]; Batista de Oliveira et al. [19]; Morais et al. [20]; ⁴ Xing et al. [21]; Polat et al. [22]; Bohutskyi et al. [23]; ⁵ Jung et al. [24]; Zhu et al. [25]; Kottuparambil et al. [26]; ⁶ Kumudha and Sarada [27]; Mixson Byrd and Burkholder [28]; Torres-Tiji et al. [7]; ⁷ Pereira et al. [29]; Schulze et al. [30]; Qazi et al. [31]. n.r—not reported.

The use of microalgae covers different areas, involving many applications. In the food industry, microalgae are used in the development of vegetarian and vegan foods as a substitute for macronutrients of animal origin, namely proteins [8,9], essential fatty acids and vitamins [5]. Furthermore, these microorganisms are employed to enrich different products, such as biscuits, nutritional bars, juices, pasta, breads, and dairy products [10,11].

In addition, microalgal biomass has been used in animal feed due to its high content of protein and carbohydrates, beyond improving the immune response and fertility in animals [32]. Another promising application of microalgae is their use in the medical field, mainly as a source of health beneficial compounds with anti-cancer, anti-inflammatory or anti-hypertensive properties [8,33]. Moreover, the use of microalgae extends to areas such as biofuel or bioplastic production, due to their high lipid and protein content [34,35,36].

In recent years, the development of new products with improved nutritional, structural and sensory characteristics has been highly demanded by consumers. Food industries are continually exploring the potential of new ingredients, and some of these innovative ingredients are referred as functional or nutraceutical ingredients, since besides their nutritional value, they also have benefits on the human body, reducing the risk of disease or improving consumers’ health [4,11]. In the last decades, there has been a rising interest in finding natural innovative, nutritive and sustainable sources to produce nutraceutical ingredients. In this sense, microalgae are considered as one of the promising sources of functional food ingredients, resulting from their large amounts of bioactive compounds [37,38]. Various studies have shown the impact of fortification with microalgal biomass on several food products such as pasta, bread, and cookies, among others, evidencing the great potential of these microorganisms, even at low levels, in the production of healthy foods [12,16,18].

On the other hand, dairy products are considered an excellent nutritional source and are widely consumed by a large part of the world’s population [39,40,41]. In addition, these products are characterized by having great benefits on human health, for instance, positive effects on bones and teeth [42,43], hypertension [44], cardiovascular diseases [45,46], gastrointestinal health [47,48], muscle repair after exercise and the immune system [49]. Moreover, fermented dairy products have been attracting special attention, as beyond their nutritional and sensory profile they are a potential source of probiotics with a remarkable impact in the food–gut axis. However, in recent years the consumption of dairy products has been decreasing, since there is skepticism among the general consumers about the health effects of dairy foods, and also an increasing public concern about their sustainability since they are products of animal origin. For this reason, the search for new, healthier and more sustainable solutions is essential.

2. Applications of Microalgal Biomass and Its Derivatives in Yogurt

Fermented milks as yogurt with probiotic microorganisms, presenting positive effects on health, are currently in high demand. Therefore, it is possible to find them in different types of markets everywhere worldwide. In order to increase their beneficial properties, there are some studies focused on the incorporation of different matrices rich in nutraceutical compounds in fermented milks, for instance, microalgal biomass or its derivatives (Table 2). In these studies, two ways to add microalgal biomass to yogurt were identified: the addition to the milk before the fermentation process (i), or the addition to the final product after the fermentation process (ii). The choice of each approach can affect the physicochemical, sensory or mechanical characteristics of the final product.

Table 2. Studies on the application of microalgal biomass or derivates in yogurt. BFP—before the fermentation process; AFP—after the fermentation process.

Microalgae or Derivate	Addition Rate	Physicochemical, Sensory, Rheology, Textural or Functional Characteristics	References
Chlorella vulgaris	0.25, 0.50 and 1% (w/v) BFP	Final acidity (°D) and final redox potential (mv) were higher than the controls, pH and acetic acid (%) values were not different compared to the controls. Oral texture and feel in the mouth, appearance and nonoral texture were lower than the control.	Beheshtipour et al. [52]
Isochrysis galbana	2% (w/w) AFP	Protein and ash percentages were higher than the controls, lipid content (%) was not different compared to the control. Levels of ω3-fatty acids were higher than the control.	Matos et al. [53]
Pavlova lutheri	0.25 and 0.5% (w/v) AFP	Moisture, carbohydrate, protein and fat contents were not different compared to the control. pH values during storage (28 days) were similar to the control. Addition rate in the treatments was negatively correlated with color, liking of flavor, liking of texture and overall acceptability.	Robertson et al. [54]
Phycocyanin from Arthrospira platensis	2, 4 and 8% (w/w) BFP	Treatments showed pH values higher than the control during 21 days of storage. Supplemented yogurts showed a lower viscosity compared to the control during 21 days of storage. Treatment with 4% of phycocyanin was the most accepted by the panelists.	Mohammadi et al. [55]
Arthrospira platensis	0.25, 0.50, 0.75 and 1% (w/v) BFP	Total solids, protein, ash and fat contents were higher than the control. There was a reduction in pH values of the treatments compared to the control. Fortified samples exhibited lower firmness compared to the control. Yogurts containing 2% of A. platensis had the highest score for acceptability.	Barkallah et al. [56]
Arthrospira platensis	1.% (w/w) AFP	Moisture, fat, protein, lactose, and ash levels were higher compared to the control. pH values in fortified samples were greater than the control as well.	Da Silva et al. [51]
Arthrospira platensis	0.13, 0.25, 0.38 and 0.5% (w/v) BFP	Acidity levels in fortified yogurt were greater than the control during 16 days of storage. Overall acceptability decreased with higher amounts of A. platensis. The antioxidant capacity was reduced during storage.	Alizadeh et al. [57]
Arthrospira platensis	1% (w/w) BFP	Ash, total solid, fat, and protein contents had an increase compared to the control. There were no significative changes in the acidity and pH values. Total phenolic content and total antioxidant activity were increased in treatments with A. platensis. Apparent viscosity values of fortified samples were greater than the control.	Atallah et al. [50]
Spirulina platensis	0.1, 0.3 and 0.5% (w/v) BFP	Solid content, protein, fat, ash, carbohydrate and acidity levels in supplemented yogurts were higher than the control. There was a reduction in the pH values compared to the control. There was an increase in hardness and viscosity values of fortified samples compared to the control.	Bchir et al. [58]

3. Applications of Microalgal Biomass and Its Derivatives in Ice Cream

Ice cream is a dairy product that has a great consumption worldwide because of its nutritional properties and refreshing effect, especially in warmer weather days. This product is made from milk, sweeteners, stabilizers, emulsifiers, flavoring and coloring agents [76]. Some studies have shown the use of microalgal biomass in ice cream due to the high presence of pigments and compounds with stabilizing roles. Since food dyes have become common in the food production industry, there has been a debate about the harmful effects of artificial food colors. Therefore, the use of natural and functional pigments has increased in the recent years [76]. Table 3 presents some research on the incorporation of microalgae and their derivatives in ice cream.

Table 3. Studies on the application of microalgal biomass or derivates in ice cream.

Microalgae or Derivate	Addition Rate	Physicochemical, Sensory, Rheological, Textural or Functional Characteristics	References
Nannochloropsis oculata	0.1, 0.2 and 0.3% (w/w)	Fortified samples were greenish in color. There were no changes in the melting behavior of fortified samples. Consistency index (K) values of the samples were close to the control.	Durmaz et al. [76]
Arthrospira platensis	0.075, 0.15, 0.23 and 0.3% (w/w)	Acidity in supplemented ice cream was increased compared to the control. pH values of fortified samples were lower than the control sample. Higher amounts of microalgae resulted in a decrease of the viscosity. Overrun in supplemented samples was enhanced compared to control.	Malik et al. [71]
Arthrospira platensis	Pure and microencapsulated with maltodextrin or Arabic gum	Protein, fat and total solid were increased in ice cream with microencapsulated or pure Spirulina compared to control. Overall acceptability was higher in ice cream without microencapsulated or pure Spirulina. Melting time in samples with pure microalgae was lower than samples with microencapsulated Spirulina.	Balensiefer et al. [77]
Arthrospira platensis	0.6 and 1.2%	Total solid, protein and fat content were increased in enriched ice cream compared to control. Ice cream overrun and melting point were higher in fortified samples. Sensory analysis showed that the panelists preferred ice cream without microalgae.	Agustini et al. [78]
Diacronema vlkianum	0.1, 0.2 and 0.3% (w/w)	Supplemented ice cream was greenish in color. The panelists found a bitter taste in enriched samples. Ice cream with microalgae showed lower K values than the control.	Durmaz et al. [76]
Phycocyanin from Arthrospira platensis	0.025%	Fortified ice cream was bluish in color (negative values of b) whereas control samples were yellowish in color (positive values of b). Antioxidant capacity of supplemented samples was improved after digestion compared to control.	Campos et al. [79]
Porphyridium cruentum	0.1, 0.2 and 0.3% (w/w)	Protein, fat and total solid were increased in ice cream with microencapsulated or pure Spirulina compared to control. Phenolic compounds increased with greater amounts of microalgae. A higher quantity of microalgae adversely affected the ice cream general sensory parameters.	Durmaz et al. [76]
Phycocyanin from Arthrospira platensis	0.013%	There was no difference in the fat content of supplemented samples compared to control. Melting time in samples with phycocyanin was lower compared to control. Overall acceptability was higher in non-fortified samples.	Rodrigues et al. [80]

4. Applications of Microalgal Biomass in Cheeses

Cheese is a highly consumed dairy product around the world with a remarkable variety of aromas and shapes associated with the interaction of milk proteins, carbohydrates and fat, and the effect of bacteria in raw milk initiates microorganisms and probiotics [90]. In order to improve the sensory, nutritional and functional characteristics of cheeses, in recent years, studies have been carried out on the incorporation of microalgal biomass. Table 4 presents some of more recent research.

Table 4. Studies on the application of microalgal biomass in cheeses.

Microalgae	Addition Rate	Physicochemical, Sensory, Rheology, Textural or Functional Characteristics	References
Chlorella vulgaris	1, 2 and 3% (w/w)	There were significant differences between the control and cheese analogue enhanced by 3% C. vulgaris biomass in all the chemical components (moisture, fat, carbohydrate and salt content). The microalgae protein and carbohydrates promoted the increase of firmness and the decrease of oil separation indexes of the cheeses.	Mohamed et al. [91]
Chlorella vulgaris	2, 4 and 6% (w/w)	The pH of the cheeses increased with the percentage of microalgae added. The addition of microalgae to the processed cheese increased the degree of meltability compared with the control sample before and after storage.	Tohamy et al. [92]
Arthrospira platensis	0.5, 1 and 1.5% (w/w)	The increase in the amount of microalgae led to a reduction in moisture and an increase in protein and fat content in soft cheese. Cheeses fortified with Spirulina showed higher values of β-carotene than then control.	Agustini et al. [78]
Arthrospira platensis	0.25, 0.5 and 1% (w/w)	There was an increase in the protein and fat content in supplemented samples compared to control. Cheeses with 0.25% and 0.5% incorporated Spirulina were mostly preferred by the panelists.	Bosnea et al. [93]
Arthrospira maxima	1, 2 and 3% (w/w).	pH of fortified samples decreased slightly compared to the control. Fat, protein and solid total content were increased in samples with 3% of microalgae. Antioxidant capacity was enhanced in supplemented samples at storage compared to the control. Overall acceptability had high scores for all treatments and control.	Mohamed et al. [94]
Arthrospira platensis	0.5, 1 and 1.5% (w/w)	Protein and ash content of enriched cheeses were not affected by microalgae addition. The L* values of Spirulina-fortified samples decreased by increasing microalgae concentration. Spirulina-fortified samples showed significantly lower degrees of hardness than the control, both at the beginning and end of storage.	Golmakani et al. [95]
Arthrospira platensis	0.5, 1 and 1.5% (w/w)	Fat and protein content of the supplemented cheeses was improved by microalgae addition compared to the control. The addition of microalgae to the cheese increased the phenolic compound and flavonoid content and also the antioxidant capacity.	Mohamed [96]

5. Other Dairy Products

The effect of the incorporation of microalgae has also been studied in some dairy products not included in the aforementioned categories, for instance: fermented milk powder, kefir, buttermilk beverage and Labenah (a product originated in the Middle East considered as a hybrid mixture between cheese and yogurt).

Vlasenko et al. [108] developed a fermented beverage based on buttermilk enriched with A. platensis at 1.0, 1.5, 2.0 and 2.5% (w/w) and the results indicated that treatments with percentages of microalgal biomass lower than 2% showed acceptable acidity values (75–80 °T); however, treatments with algae concentrations greater than 2% resulted in very high acidity values (87–90 °T). Due to a higher substrate concentration, lactic acid bacteria were able to produce a higher amount of lactic acid during fermentation [109]. The fat content value for all treatments and the control was 0.4% (p > 0.05).

Martelli et al. [110] reported the effect of adding A. platensis (0.25 and 0.5% w/v) and Lactobacillus bulgaricus and Streptococcus thermophilus in reconstituted fermented milk powder (10% w/v), and it was observed that there was a significant decrease in the pH values (4.3 and 4.1) when the microalgae concentration was increased. This behavior is similar to that reported by Varga et al. [111], who observed a decrease in pH values in milk containing A. platensis and inoculated with S. thermophilus and L. bulgaricus when the algae concentration was increased. Likewise, the authors studied the effect of microalgal biomass addition on rheological behavior in terms of flow index (n) and consistency index (K). The results showed that there was a decrease in K values (2.56 and 1.77 Pa.sⁿ) with the addition of 0.25 and 0.5% A. platensis, related to a reduction in the consistency when compared to the control sample (product without microalgae). The values of flow index (n) were increased with microalgae addition, ranging from 0.366 to 0.439, revealing a reduction in the shear thinning behavior.

Mohamed et al. [112] developed a high-quality protein Labenah enriched with A. platensis (0.5% w/w), and the results indicated that there was a significant increase in protein content (13.08% w/w) when compared to a control sample of 10.60% w/w. Microalgal biomass of A. platensis is known to have high levels of protein [18,19], and therefore its incorporation in Labenah resulted in an increase in the content value of this macronutrient. A similar trend was observed by Laela et al. [113], who reported a protein content of 5.53% in kefir fortified with 2% A. platensis compared to 4.02% in the control sample. In addition, the effect of storage on the acidity level of Labenah was also evaluated. Mohamed et al. [112] observed that there was an increase in the acidity values of this product, going from 2.2% (day 0) to 2.8% lactic acid (day 27) in samples enriched with A. platensis (0.5% w/w). This increase was more significant than in the control sample (from 1.7 to 1.8% lactic acid on day 0 and 27, respectively), which indicates that lactic acid production was beneficially influenced by the addition of microalgal biomass.

This entry is adapted from the peer-reviewed paper 10.3390/foods11050755

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