Stability of Fatty Acids, Tocopherols, and Carotenoids of Sea Buckthorn Oil Encapsulated by Spray Drying Using Different Carrier Materials

Abstract

The aim of this study was to determine the retention of fatty acids, α-tocopherol, and carotenoids in sea buckthorn oil (SBO) encapsulated with gum arabic (GA), β-cyclodextrin (β-CD), and their mixture (1:1) under pre-optimized spray drying conditions in comparison to the bioactive molecule (BAM) content of the non-encapsulated oil. In addition, the color parameters in the spray-dried powders and the bioaccessibility of β-carotene, which has the highest provitamin A activity, were evaluated. The fatty acid content remained almost unchanged, while statistically significant differences in α-tocopherol and carotenoid content were found between the SBO encapsulated with different carriers and the non-encapsulated oil. The retention of tocopherols and carotenoids compared to the non-encapsulated SBO ranged from 62.13 to 87.23% and from 21.17 to 97.61%, respectively. SBO encapsulated with β-CD showed significantly higher retention of α-tocopherol (87.23%) and individual carotenoids (40.71–97.61%). In addition, the powders showed no significant differences in color parameters, and the powders encapsulated with GA and β-CD showed high bioaccessibility of β-carotene (92.50 and 90.45%, respectively). β-CD proved to be the most suitable carrier for the encapsulation of the carotenoids and α-tocopherol of SBO, resulting in powders with high bioaccessibility of β-carotene.

1. Introduction

The sea buckthorn (Elaeagnus rhamnoides (L.) A. Nelson) berry is known as an important source of natural antioxidant and antimicrobial bioactive molecules (BAM) with numerous health benefits. The most valuable sea buckthorn product is the berry oil (SBO), with intense color due to its high content of carotenoids such as zeaxanthin and β-carotene [1]. The oil has a unique richness in saturated (palmitic acid and stearic acid), and polyunsaturated essential fatty acids (α-linolenic acid, ɣ-linolenic acid, linoleic acid, palmitoleic acid, and oleic acid), which contribute to its nutritional profile and provide a variety of health-promoting properties. SBO also contains significant amounts of tocopherols, especially α-tocopherol, the main vitamin E compound, which has a strong antioxidant effect and is, therefore, important for the oxidative stability of the oil [2]. The presence of omega fatty acids and fat-soluble vitamins in oils can improve the bioaccessibility and bioavailability of carotenoids [3], which is particularly important for the bioavailability of β-carotene, the most potent precursor of vitamin A, which is a necessary nutrient for the eyes, immune system, reproduction, cell differentiation, and embryonic development [4]. However, in the food industry, the use of the oil is limited because of the instability of these lipophilic BAM during the various stages of food production and storage, as well as their low bioavailability, poor water solubility, rapid release and chemical instability, and high susceptibility to oxidation under various environmental conditions (oxygen, acids, metal ions, light, and high temperatures) [5]. Therefore, in order to utilize their nutritional and pharmaceutical benefits, it is important to preserve these valuable compounds. In this sense, encapsulation technology has been used to protect pigments and other valuable molecules and to produce lipophilic powders with suitable properties for food applications and development of functional foods. Encapsulation is based on the coating of the core material or active molecule with a carrier or dispersion in a polymer matrix, creating solid or liquid particles capable of protecting the encapsulated material by forming a physical barrier against the external environment. It is, therefore, a useful method for improving the distribution of BAM in food and its delivery to the gastrointestinal tract. Except the protection and controlled release of lipophilic BAM, encapsulation can also provide other benefits, such as masking undesirable odors and bitter tastes of certain oils, improved water dispersibility of fat-soluble compounds, and easier handling and storage of powders [6,7]. A cost-effective, simple, flexible, and widely used encapsulation technique in food and pharmaceutical industries to preserve heat-sensitive molecules is spray drying (SD) [8,9]. In SD, an emulsion containing BAM is atomized in hot air, allowing the solvent to be quickly removed to obtain powdered products [10]. SD can protect oil droplets in an emulsion from lipid oxidation, especially oils rich in polyunsaturated fatty acids which have a high tendency to demonstrate oxidative deterioration and the formation of undesirable flavors [11]. However, despite rapid SD (a few seconds), high drying temperatures (150 to 250 °C) are used, and excessively high inlet temperatures can lead to heat degradation, alter heat-sensitive products, and cause defects on the membrane surface of the dried product, which increase the loss of BAM during SD [12,13] and, consequently, affect the color of spray-dried products [14].

The proper selection of the type and concentration of carrier with good protective effect reduces the influence of SD on the retention of BAM [15] and affects the properties of the spray-dried powders produced [16]. In fact, the protection or controlled release of BAM and the masking of unpleasant tastes or odors depends primarily on the structure and content of the carrier, as the carrier can act as a barrier to oxygen, water, light, and other constituents. Numerous carrier materials were tested for their suitability as carrier material for SD, and considering the hydrophobic nature of oils, carriers with good emulsifying properties are more suitable for the encapsulation and protection of this type of core [17].

For the encapsulation of lipophilic BAM by SD, gum arabic (GA) and β-cyclodextrin (β-CD) are usually used [15,18,19]. GA can interact with both hydrophobic and hydrophilic compounds due to its branched carbohydrate chain and the presence of glycoproteins linked by covalent bonds. β-CD is composed of seven glucopyranose units in the shape of a truncated cone with a molecule that is hydrophilic outside and hydrophobic inside and is suitable for the entrapment of hydrophobic compounds as it forms inclusion complexes in the hydrophobic central cavity [19]. Due to these properties, cyclodextrins have good biocompatibility and an excellent ability to encapsulate a variety of guest molecules [20]. The combination of carrier materials instead of using a single carrier material could lead to a higher retention of BAM due to their different properties [19].

To the best of our knowledge, there is limited information on how SD conditions affect the retention of lipophilic compounds in encapsulated SBOs. Therefore, the aim of this study was to determine the retention of fatty acids, α-tocopherol, and carotenoids in the encapsulated SBOs using GA, β-CD, and their mixture (1:1) at optimal SD conditions in comparison to the BAM content of the SBO. In addition, the color parameters in the spray-dried powders and bioaccessibility of β-carotene, which has the highest provitamin A activity, were evaluated.

2. Materials and Methods

2.1. Materials

SBO was obtained by Supercritical CO₂ extraction in an supercritical fluid extraction (SFE) system according to Čulina et al. [21] and used for SD. GA and β-CD (Sigma-Aldrich, Taufkirchen, Germany) and their mixture (1:1) were used as carrier materials and Tween 20 (Sigma-Aldrich, Taufkirchen, Germany) as surfactant for the preparation of the oil-in-water emulsion.

2.2. Spray Drying

SD was performed (SD 06 Labplant, North Yorkshire, UK) under the pre-optimized SD conditions defined in the previous study by Čulina et al. [21], which include the following: carrier-to-oil ratio of 2.7 for GA, 4 for β-CD, and 3.2 for GA:β-CD (1:1) and drying temperature of 120 °C. The solutions of GA, β-CD, and the mixture of GA and β-CD (1:1) were prepared by dissolving the carriers in distilled water with constant stirring (800 rpm) at a constant temperature of 50 ± 1 °C overnight. After the complete saturation of the polymer molecules, 1 g of the surfactant Tween 20 and 15 g of SBO were added and homogenized (20,000 rpm/5 min) at room temperature using an Ultra-Turrax (T25, IKA, Staufen, Germany). The spray-dried SBO powders were collected and transferred to opaque and airtight containers and stored at 20 °C in a desiccator until analysis.

2.3. Characterization of the Encapsulated SBO

2.3.1. Fatty Acid Composition

The preparation of fatty acid methyl esters (FAMEs) and their determination by gas chromatography was carried out according to the ISO 12966-2:2017 [22], ISO 12966-4:2015 [23], and Balbino et al. [24]. The FAMEs were separated on a TRACE TR-FAME capillary column (30 m × 0.22 mm × 0.25 µm) with a stationary phase of 70% cyanopropyl polysilphenylene–siloxane (Thermo Scientific, Waltham, MA, USA) and identified by comparing their retention time (Rt) with an authentic standard mixture of 37 component FAMEs (C4–C24) (Supelco, Sigma-Aldrich, St. Louis, MO, USA). The results were expressed as a percentage of total fatty acids (%).

2.3.2. α-Tocopherol Content

The SBO oil and powders were diluted in n-hexane, and the chromatographic separation of α-tocopherol was performed on an Agilent 1260 Infinity quaternary liquid chromatography system with fluorescence detector (HPLC-FID) (Agilent Technologies, Santa Clara, CA, USA) using a LiChroCART Silica 60 column (250 mm 94.6 mm, 5 L; Merck, Darmstadt, Germany) according to method ISO 9936-1:2016 [25]. A standard calibration curve of D-α-tocopherol (Sigma-Aldrich, St. Louis, MO, USA) was used for quantification. The results were expressed in mg per 100 g of oil (mg/100 g).

2.3.3. Carotenoid Composition

High-performance liquid chromatography coupled to a diode array detector (HPLC-DAD, Agilent Technologies, Santa Clara, CA, USA) was used for carotenoid determination according to the method of Castro Puyana et al. [26]. The analysis was performed in an Agilent 1260 Infinity quaternary LC system (Agilent Technologies, Santa Clara, CA, USA) and the separation was performed on a Develosil RP-Aqueous (C30) reversed-phase column (250 mm × 4.6 mm i.d., 5 µm particle size) (Phenomenex, Torrance, CA, USA). The carotenoids were detected at 450 nm and identified based on the Rt of authentic standards for lutein, zeaxanthin, and β-carotene (Sigma-Aldrich, St. Louis, MO, USA) and absorption spectra reported in the literature [27]. Quantification was performed using calibration curves of above-mentioned standards. The results were expressed in mg per 100 g of oil (mg/100 g).

2.3.4. Determination of Color Parameters

The color of the SBO powders was evaluated with a colorimeter (CM-3500d, Konica Minolta, Japan) according to the CIELab color system. The device was calibrated with a white and black standard plate. The measured parameters were degree of lightness/darkness (L*), redness and greenness (positive and negative a*), and yellowness and blueness (positive and negative b*). The H*-value (hue angle) calculated as arctan b*/a* is the color tone or tonality, i.e., the visual experience that represents the sensation caused by different parts of the spectrum with the same brightness. The C-value (chroma, saturation) represents the color intensity or color saturation, which is calculated according to Equation (1):

C = (a*² + b*²)^1/2

(1)

2.3.5. Bioaccessibility

The in vitro bioaccessibility of β-carotene was assessed by the simulation of gastrointestinal digestion using the harmonized static approach previously described by Brodkorb et al. [28] with some modifications. Firstly, 500 mg of SBO was mixed with 2 mL of ultrapure water and then combined with SGF in 1:1 ratio (v/v), as suggested by the original procedure [25]. The samples were incubated for 2 h at 37 °C in a water bath (Büchi B-490, Flawil, Switzerland), maintaining constant shaking at 110 rpm. Following the incubation, SIF was added to the mixture, where the gastric chime–SIF ratio was set to 1:1 as suggested by the original method [25]. The simulation of intestinal digestion was conducted by shaking the samples for subsequent 2 h, at 37 °C in the shaking water bath (110 rpm). To eliminate the crude components from the sample, the mixture was placed on ice for 10 min and then centrifuged for 20 min at 4 °C at 4100× g rpm. Enzyme activity in collected supernatants containing bioavailable fraction was halted by subjecting the sample to a heat shock at 100 °C for 5 min using a Thermomixer R (Eppendorf, Hamburg, Germany). Afterwards, the samples were cooled in an ice bath for another 10 min before being centrifuged, again under identical conditions. The resulting supernatant, which represented the bioavailable fraction of the samples, was stored at −80 °C until further analysis. A blank sample containing only the digestion solutions was also prepared to ensure that there were no interferences from the reagents used. The β-carotene concentrations were quantified following the official AOAC method [29]. The β-carotene bioaccessibility after the simulation of gastrointestinal digestion was determined by calculating the percentage (%) according to Equation (2):

% Bioaccessibility = (amount in bioaccessible fraction/amount in undigested extract) × 100

(2)

2.3.6. Experimental Design and Statistical Analysis

Statistica ver. 10.0 (Statsoft Inc., Tulsa, OK, USA) was used for the statistical analysis. One-way ANOVA and Tukey’s HSD test were performed to compare the mass concentrations of different lipophilic molecules (fatty acids, α-tocopherol, and carotenoids) of encapsulated SBO and non-encapsulated SBO and to evaluate the influence of different carriers (GA, β-CD and GA:β-CD (1:1)) on the retention of fatty acids, α-tocopherol, and carotenoids. In addition, the influence of the carriers on the color parameters and bioaccessibility of β-carotene in the obtained powders was investigated. All tests were performed with a significance level of p ≤ 0.05. The results of the statistical analysis are expressed as mean ± standard error (SE).

3. Results and Discussion

The fatty acid and α-tocopherol content as well as the individual carotenoid content of the encapsulated SBO using three different carriers were determined by HPLC-DAD, GC-MS, and HPLC-FID, respectively. The mean values of determined BAMs in encapsulated and non-encapsulated SBOs were compared, and the results are shown in

Table 1. Fatty acid composition (weight percentage of total fatty acids) of non-encapsulated SBO and encapsulated SBO produced by spray drying using gum arabic, β-cyclodextrin, and their mixture.

Fatty Acids		SBO	SD-GA	SD-β-CD	SD GA:β-CD (1:1)
Saturated (%)
Myristic	p = 0.07	0.15 ± 0.01 a	0.18 ± 0.00 a	0.17 ± 0.00 a	0.16 ± 0.00 a
Pentadecanoic acid	p = 0.94	0.07 ± 0.01 a	0.07 ± 0.00 a	0.07 ± 0.00 a	0.07 ± 0.00 a
Palmitic	p = 0.36	25.44 ± 1.05 a	25.20 ± 0.00 a	25.49 ± 0.00 a	25.38 ± 0.01 a
Heptadecanoic acid	p = 0.27	0.11 ± 0.01 a	0.14 ± 0.00 a	0.15 ± 0.00 a	0.14 ± 0.00 a
Stearic	p = 0.83	1.59 ± 0.02 a	1.59 ± 0.00 a	1.63 ± 0.00 a	1.66 ± 0.00 a
Arachidic acid	p = 0.08	0.28 ± 0.02 a	0.24 ± 0.00 a	0.28 ± 0.00 a	0.29 ± 0.00 a
Docosanoic acid	p = 0.65	0.12 ± 0.01 a	0.13 ± 0.00 a	0.13 ± 0.00 a	0.12 ± 0.01 a
SUM:	p = 0.20	27.76 ± 0.06 a	27.55 ± 0.00 a	27.92 ± 0.01 a	27.81 ± 0.01 a
Unsaturated (%)
Monounsaturated (%)
Palmitoleic acid	p = 0.27	31.85 ± 1.15 a	31.67 ± 0.01 a	31.26 ± 0.00 a	30.94 ± 0.01 a
Oleic acid	p = 0.84	16.38 ± 1.04 a	16.36 ± 0.02 a	16.57 ± 0.01 a	16.53 ± 0.01 a
Vaccenic acid	p = 0.74	7.43 ± 1.03 a	7.40 ± 0.01 a	7.28 ± 0.00 a	7.24 ± 0.00 a
SUM:	p < 0.01	55.66 ± 0.09 b	55.44 ± 0.02 b	55.11 ± 0.00 a	54.71 ± 0.00 a
Polyunsaturated (%)
Linoleic acid	p = 0.35	11.20 ± 0.45 a	11.32 ± 0.01 a	11.75 ± 0.00 a	12.01 ± 0.00 a
α-Linolenic acid	p = 0.43	5.24 ± 0.14 a	5.35 ± 0.00 a	5.17 ± 0.00 a	5.14 ± 0.00 a
SUM:	p = 0.28	16.44 ± 0.45 a	16.67 ± 0.02 a	16.93 ± 0.00 a	17.15 ± 0.00 a

Results are expressed as mean ± standard error. Values with different letters within a row are significantly different at p ≤ 0.05. SBO = Sea buckthorn oil, SD-GA = encapsulated oil produced by spray drying using gum arabic, SD-β-CD = encapsulated oil produced by spray drying using β-cyclodextrin, SD-GA:β-CD (1:1) = encapsulated oil produced by spray drying mixture of gum arabic and β-cyclodextrin.

and

Table 2. Carotenoid content (mg/100 g) of non-encapsulated SBO and encapsulated SBO produced by spray drying using gum arabic, β-cyclodextrin, and their mixture.

Carotenoids		SBO	SD-GA	SD-β-CD	SD-GA:β-CD (1:1)
Zeaxanthin	p < 0.05	8.77 ± 0.02 c	3.62 ± 0.09 a	4.42 ± 0.09 b	3.46 ± 0.13 a
β-cryptoxanthin	p < 0.01	6.85 ± 0.03 d	1.45 ± 0.12 a	3.26 ± 0.01 c	2.56 ± 0.07 b
γ-carotene	p < 0.01	0.18 ± 0.00 c	0.13 ± 0.00 a	0.16 ± 0.00 b	0.12 ± 0.00 a
cis γ-carotene	p < 0.01	1.18 ± 0.00 c	0.68 ± 0.03 a	0.97 ± 0.01 b	0.77 ± 0.02 a
β-carotene	p < 0.05	2.09 ± 0.01 c	0.55 ± 0.01 a	2.04 ± 0.00 c	1.32 ± 0.06 b
β-cryptoxanthin palmitate	p < 0.01	0.14 ± 0.00 d	0.03 ± 0.00 a	0.07 ± 0.00 c	0.05 ± 0.00 b
Zeaxanthin-myristate	p < 0.01	28.65 ± 0.09 d	9.51 ± 0.11 a	23.44 ± 0.51 c	16.62 ± 0.55 b
Lutein-palmitate	p < 0.01	3.30 ± 0.10 c	0.78 ± 0.00 a	3.12 ± 0.10 b,c	2.21 ± 0.34 b
Zeaxanthin-pamitate	p < 0.01	31.01 ± 0.04 d	16.83 ± 0.35 a	24.78 ± 0.66 c	19.14 ± 0.06 b
Lutein di-myristate	p < 0.05	10.39 ± 0.02 c	2.40 ± 0.19 a	4.23 ± 0.01 b	2.96 ± 0.24 a
Zeaxanthin-palmitate-myristate	p < 0.01	36.22 ± 0.03 b	27.01 ± 0.51 a	27.18 ± 0.24 a	27.25 ± 0.97 a
lutein di palmitate	p < 0.01	24.17 ± 0.03 d	16.00 ± 0.16 a	22.36 ± 0.19 c	19.15 ± 0.28 b
Zeaxanthin-di-palmitate	p < 0.01	58.08 ± 0.03 d	34.53 ± 0.14 a	54.61 ± 0.32 c	46.29 ± 0.01 b
Lutein palmitate stearate	p < 0.01	4.37 ± 0.02 d	1.16 ± 0.06 a	3.12 ± 0.00 c	1.94 ± 0.01 b
SUM:	p < 0.01	215.40 ± 0.18 d	114.68 ± 0.90 a	173.76 ± 0.22 b	143.84 ± 0.95 c

Results are expressed as mean ± standard error. Values with different letters within a row are significantly different at p ≤ 0.05. SBO = Sea buckthorn oil, SD-GA = encapsulated oil produced by spray drying using gum arabic, SD-β-CD = encapsulated oil produced by spray drying using β-cyclodextrin, SD-GA:β-CD (1:1) = encapsulated oil produced by spray drying mixture of gum arabic and β-cyclodextrin.

and Figure 1.

The sea buckthorn berries contained 14.47% oil and spray-dried powders obtained with GA, β-CD, and GA:β-CD (1:1) contained 10.30%, 25.57%, and 13.00% oil, respectively. The fatty acid composition of the encapsulated oil was the same as that of the non-encapsulated oil, with unsaturated fatty acids predominating, including monounsaturated fatty acids, such as palmitoleic acid (30.94–31.67%), oleic acid (16.36–16.57%), and vaccenic acid (7.24–7.40%), and polyunsaturated fatty acids, such as linoleic acid (11.32–12.01%) and α-linolenic acid (5.14–5.35%). Among saturated fatty acids, palmitic acid (25.20–25.49%) was the most abundant, followed by stearic acid (1.59–1.66%), arachidic acid (0.24–0.29%), myristic acid (0.16–0.18%), heptadecanoic acid (0.14–0.15%), docosanoic acid (0.12–0.13%), and pentadecanoic acid (0.07%). As shown in Table 1, a considerable retention of fatty acids was in encapsulated SBOs; the total saturated fatty acid content decreased by 0.21% in oil encapsulated with GA, while it increased by 0.06% and 0.05% in the oil encapsulated with β-CD and a mixture of GA and β-CD (1:1), respectively. The total polyunsaturated fatty acid content increased in all encapsulated oils, namely by 0.23% in the powders encapsulated with GA, by 0.49% in the β-CD powders, and by 0.71% in the powders using a mixture of GA and β-CD, but these differences were not significant. In contrast, the total monounsaturated fatty acid content decreased statistically significantly (p < 0.05) in oil encapsulated with β-CD and a mixture of GA and β-CD (0.55 and 0.99%, respectively), while no significant difference was found when comparing the retention of individual monounsaturated fatty acids. It is likely that the intermolecular forces between carriers and fatty acids in oils leading to the formation of inclusion complexes, van der Waals and electrostatic interactions, hydrophobic transfer interactions, hydrogen bonding, release of conformational stresses, and exclusion of high-energy bonds in cavities contribute to their thermal stability [30]. For example, Liu et al. [30] reported improved thermal stability of oleic acid due to host–guest interactions between oleic acid and β-CD. In addition, other lipophilic compounds present in SBO are also important for the preservation and conservation of oxidizable fatty acids, as they can delay or interrupt the oxidation of large unsaturated hydrocarbon chains, such as PUFAs [31,32,33,34]. In addition, tocopherols can improve the oxidative stability of vegetable oils exposed to high temperatures because of their ability to transfer a hydrogen atom to peroxyl radicals faster than unsaturated fatty acids, resulting in hydroperoxides and tocopheroxyl radicals that are more stable than peroxyl radicals [35]. Hogan et al. [36] reported an antioxidant effect of the addition of α-tocopherol to fish oil subjected to SD. In agreement with our results, Wang et al. [37] also reported no significant effect of the SD method on the fatty acid composition in peony oil, which was characterized by a high PUFA content of α-linolenic acid (39.24%) and ɣ-linolenic acid (26.96%). Castejón et al. [38] and Damerau et al. [39] also reported that encapsulation by SD had no effect on the omega-3 fatty acid profile when different carriers were used, i.e., sodium caseinate and lactose, sunflower, pea, and soy proteins in combination with maltodextrin or whey protein. In contrast, Calvo et al. [40] reported that the SD of extra virgin olive oils significantly changed the fatty acid composition, and reduced the PUFA content by 5.3–69.6% depending on the olive variety. Rubilar et al. [41] also reported a reduction in PUFAs in spray-dried linseed oil. The studies of Ogrodowska et al. [42,43] also reported significant changes in the fatty acid content of spray-dried pumpkin seed oil and evening primose oil. It is, therefore, important to select suitable carrier materials and operating SD parameters to reduce the loss of fatty acids.

The α-tocopherol content of the encapsulated SBOs varied between 63.65 and 89.37 mg/100 g (Figure 1). ANOVA showed that the mass concentration of α-tocopherol decreased statistically significantly compared to the non-encapsulated oil (p < 0.05). Furthermore, there were significant differences in α-tocopherol content between oils encapsulated with different carriers. Oil encapsulated with a β-CD carrier had a significantly higher retention of α-tocopherol (87.23%) compared to oil encapsulated with GA and a mixture of GA and β-CD carriers (62.13 and 66.30%, respectively). Various studies have shown that inclusion complexes with β-CD are more stable against oxidation compared to other carrier materials [44,45,46,47]; therefore, lower losses in α-tocopherol were observed in oils encapsulated with β-CD. Similar losses in α-tocopherol in spray-dried powders have been reported in other studies. For example, in the study by Ogrodowska et al. [48], the α-tocopherol content in spray-dried rapeseed oil decreased by 16.8%, while δ-tocopherol was completely degraded. In encapsulated linseed oil, α-tocopherol remained stable, while it decreased by 54.7% in the encapsulated safflower oil. Gawrysiak-Witulska et al. [47] investigated the effects of drying temperature on the changes in individual tocopherol homologues in yellow-grained rapeseed oil and reported that the losses in α-tocopherol did not exceed 2% when drying was at 40 °C and 60 °C while increasing the temperature to 100 °C and 120 °C resulted in higher losses in α-tocopherol (23%).

In the study by Ogrodowska et al. [42], the loss in the total tocopherol content in encapsulated evening primrose oil was about 60%, while lower losses of 9.5% and 15% were found for encapsulated borage and red cabbage oil.

The carotenoid profile of the encapsulated SBOs was the same as that of the non-encapsulated oil, which was characterized by the following compounds: carotenoid zeaxanthin, β-cryptoxanthin, γ-carotene, cis-γ-carotene, and β-carotene in free form and the esterified forms of zeaxanthin (zeaxanthin-myristate, zeaxanthin-pamitate, zeaxanthin-palmitate-myristate, zeaxanthin-di-palmitate), lutein (lutein-palmitate, lutein di-myristate, lutein di-palmitate, lutein-palmitate-stearate), and β-crypoxanthin (β-cryptoxanthin-palmitate). The total content of carotenoids in the encapsulated SBOs varied between 114.68 and 173.76 mg/100 g. The most abundant compounds were zeaxanthin and lutein esters as follows: zeaxanthin di-palmitate (34.53–54.61 mg/100 g), zeaxanthin-palmitate-myristate (27.01–27.25 mg/100 g), zeaxanthin-palmitate (16.83–24.78 mg/100 g), lutein di-palmitate (16.00–22.36 mg/100 g), and zeaxanthin-myristate (9.51–23.44 mg/100 g). Lutein-palmitate, lutein di-myristate, and β-cryptoxanthin-palmitate were identified in a significantly lower concentration (0.03–4.23 mg/100 g). The free forms of carotenoids accounted for less than 10% of the total carotenoids in encapsulated SBO, with the mass concentration of β-carotene ranging from 0.55 to 2.04 mg/100 g. ANOVA showed that the mass concentration of individual and total carotenoid contents decreased statistically significantly (p < 0.05) in all encapsulated oils compared to non-encapsulated oil, but no significant difference was found for β-carotene and lutein-palmitate in oil encapsulated with β-CD and non-encapsulated oil (Table 2). Furthermore, there were significant differences in carotenoid content between oils encapsulated with β-CD compared to GA and a mixture of GA and β-CD, with the exception of zeaxanthin-palmitate-myristate. The highest mass concentrations of total carotenoids determined by HPLC were found in oil encapsulated with β-CD, and a loss of less than 10% of β-carotene, lutein-palmitate, lutein di-palmitate, and zeaxanthin di-palmitate was observed. In addition, high retention was observed for γ-carotene (88.89%), cis γ-carotene (82.20%) zeaxanthin-myristate (81.82%), zeaxanthin-palmitate (79.90%), and lutein-palmitate-stearate (71.40%). The better retention of carotenoids with β-CDs can be explained by their ability to rapidly replace the water molecules inside the ring with non-polar molecules that have a higher affinity for the CDs. This process of forming the host–guest inclusion complexes is thermodynamically advantageous [49]. Moreover, β-CD was added in a larger proportion compared to other carriers, and the time required for the formation of a surface crust during the initial drying process decreases with increasing solid concentration in the feed solution, and the formed crust is not permeable to compounds and protects the BAM from oxidation [50,51]. β-cryptoxanthin and lutein di-myristate showed poorer stability during SD with β-CD, and their loss was more than 50%. Zeaxanthin-palmitate-myristate losses were similar for all encapsulated oils and amounted to less than 30%. On the other hand, the highest losses in carotenoids were observed when GA carrier was used, namely, β-cryptoxanthin, cis γ-caroten, β-carotene, zeaxanthin-myristate, lutein-palmitate, zeaxanthin-pamitate, lutein di-palmitate, zeaxanthin-di-palmitate, and lutein-palmitate-stearate. GA in combination with another carrier shows better encapsulation properties; therefore, the mixture of GA and β-CD contributed to a lower loss of the mentioned compounds. Similar studies showed better properties of GA in combination with other carriers such as maltodextrin [52,53]. The choice of carrier material and the structural properties of the pigments influence the stability of the carotenoids during encapsulation [54].

The carotenoid pigments are responsible for the color of the SBO powders, and an analysis of the color parameters was performed according to the CIELab color system. The mean values of the parameters L*, a*, b*, H*, and C* for each carrier were compared, and the results are shown in

Table 3. Color parameters of powders produced by spray drying using gum arabic, β-cyclodextrin and their mixture.

Source of Variation	L*	a*	b*	H*	C*
	p = 0.55	p = 0.61	p = 0.12	p = 0.21	p = 0.14
SD-GA	86.53 ± 1.12 a	11.26 ± 0.98 a	43.98 ± 1.24 a	75.67 ± 0.81 a	45.40 ± 1.14 a
SD-β-CD	88.51 ± 1.22 a	11.25 ± 0.97 a	38.56 ± 1.31 a	73.77 ± 0.81 a	40.17 ± 0.99 a
SD-GA:β-CD (1:1)	87.05 ± 1.26 a	12.44 ± 0.69 a	42.19 ± 1.28 a	73.58 ± 0.39 a	43.99 ± 1.81 a

Results are expressed as mean ± standard error. Values with different letters within a row are significantly different at p ≤ 0.05. SD-GA = powder produced by spray drying using gum arabic, SD-β-CD = powder produced by spray drying using β-cyclodextrin, SD-GA:β-CD (1:1) = powder produced by spray drying mixture of gum arabic and β-cyclodextrin.

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Similar values were determined for the parameter L*; 86.53 for the powder spray dried with GA, 88.51 for the powder with CD and 87.05 for the powder spray dried with mixture of GA and β-CD (1:1). The color parameter L* indicates the brightness of the powder (100 = light to 0 = black), and since the color of the SBO is orange-red, an orange-yellow color of the powder was preferred. A positive a* value indicates a higher proportion of red in the powder, while a negative a* value indicates a higher proportion of green. All powders had a positive value for the a* parameter; 11.26 powders spray dried with GA, 11.25 for β-CD and 12.44 powders spray dried with a mixture of GA and β-CD, indicating that the red color dominated in the powders. A positive value of the color parameter b* indicate a yellow color, and negative values indicate a blue color. For all powders, the values of the parameter b* were positive (43.98 for GA, 38.56 for β-CD, and 42.19 for the mixture of GA and β-CD, respectively), indicating the yellow color of the powders. The hue (H) parameter is described as a rainbow or spectrum of colors; the H values 0° or 360° correspond to the red color tone, yellow corresponds to 90°, blue-green 180°, and blue 270°. According to the H* values obtained, yellow color tones predominate in the SBO powders (75.67 for GA, 73.77 for β-CD, and 73.58 for the mixture of GA and β-CD carriers). The values of the color parameter C* (chroma,) which indicates the intensity of the color in SBO powders, were 42.26 for GA, 40.17 for β-CD, and 50.21 for the mixture of GA and β-CD. Heat treatment may lead to the degradation and isomerization of the carotenoids, which would reduce the yellow color of the samples [55].

Statistical analysis showed no significant difference (p > 0.05) in color parameters between powders obtained with different carriers, although significantly higher concentrations of pigments responsible for the color were detected in powders with β-CD. Probably a higher concentration of β-CD in the original emulsion, affected brighter color of the obtained powders. Peng et al. [56] and Caparino et al. [14] also reported that the brightness of powders depends on the proportion of carriers used in powder production and that color is one of the most important sensory parameters determining the acceptability of products for food and pharmaceutical applications.

Due to the health-promoting properties of carotenoids, they are increasingly being used for food fortification, and their daily consumption is strongly recommended. β-Carotene, an essential source of vitamin A in the human diet, is very sensitive to chemical degradation due to its unsaturated groups, particularly when exposed to pro-oxidants, high temperatures, and light [57]. Encapsulation allows the carotenoids to be more easily distributed in the diet, which increases their solubility and, consequently, their accessibility and availability in the gut [58,59]. The bioaccessibility of β-carotene in powders obtained by SD using GA, β-CD, and their mixture is shown in Figure 2 and ranges from 83.58 to 92.51%.

The results obtained show excellent gastrointestinal stability and bioaccesibility of β-carotene, indicating a high applicability of SD as the technique of choice for carotenoid encapsulation. This is in line with recent research indicating that the SD method is more suitable than freeze-drying for the encapsulation of carotenoids, as it improves their stability and enhances the bioaccessibility to a greater extent [60].

Recent studies have reported good protection of carotenoids by microencapsulation [61,62], i.e., Sun et al. [62] and Zhou et al. [63] reported that carrier materials effectively protect fucoxanthins and astaxanthins in the gastric environment, thus improving their bioaccessibility [62,63]. The choice of encapsulation agent may play an important role in determining the bioaccessibility of β-carotene. Such effects are generally achieved by influencing carotenoid stability, release mechanisms, interaction with lipids, or physical properties of the particles [64]. According to the study by Nagao et al. [65], the fatty acid composition of the oil has an influence on the bioavailability of carotenoids. For example, the bioaccessibility of carotenoids was positively influenced by the presence of monounsaturated fatty acids such as oleic acid, which is present in high concentrations in SBO used in our study. A statistically significantly higher bioaccessibility of β-carotene was observed when powders were produced using GA (92.51%) and β-CD (90.45%) compared to a mixture of GA and β-CD (83.58%). The bioaccessibility of β-carotene from encapsulated extracts of mango by-products with inulin as a carrier was also relatively stable, as total recoveries were above 68% [66]. Lower bioaccessibility of β-carotene was reported when alginate hydrogel beads were used (36–51%) [67,68].

Our results indicate the high potential of SBO powders for application in functional foods with provitamin A activity.

In conclusion, the use of β-CD as carrier material and SD conditions with a drying temperature of 120 °C and a carrier-to-oil ratio of 4 was found to be the most suitable for the production of spray-dried SBO powders with the highest retention of BAMs in encapsulated oil and high β-carotene bioaccessibility.

4. Conclusions

Sea buckthorn oil was successfully encapsulated by spray drying using gum arabic, β-cyclodextrin, and their mixture as carrier materials, and all powders produced showed high fatty acid stability (decrease below 1%). Spray drying and carrier material affected more the content of α-tocopherol and carotenoids in the encapsulated oils, and the highest retention was observed in the oils encapsulated with β-cyclodextrin (87.23% for α-tocopherol and from 71.40% to 97.61% for carotenoids). The spray drying of sea buckthorn oil had no effect on the color of the powders and resulted in high bioaccessibility of β-carotene (83.58–92.50%), regardless of the carrier used. In conclusion, the carrier materials used in this study are well suited for the stability of lipophilic molecules of interest in the production of spray-dried powders with sea buckthorn oil and provide a valuable reference for their application in food processing.