Evaluation of spray-drying´s operable condition for obtaining orange juice powder: effects on physicochemical properties

ABSTRACT

The objective of the present work was to determine the effects of the main variables of spray drying to obtain orange juice powder as an alternative method for the integral use of orange juice. The variables evaluated for the spray-drying were the air inlet temperature, feed flow, and maltodextrin concentration, which had a different degree of significance on the assessed responses, the air inlet temperature is the one that had a more significant degree on the moisture content (p ≤ 0.01) and polyphenol content (p ≤ 0.05). While the maltodextrin concentration was for the yield and moisture content (p ≤ 0.05). However, on the color attributes, no significant effects were observed under the evaluated variables. Therefore, using spray-drying an orange juice powder with stable physicochemical characteristics was obtained, using maltodextrin 7% (w/w) and 0.1% (w/v) sodium alginate as carrier agents, 160°C inlet air temperature, 14 mL/min feed flow, which will allow the use of this drying technology.

RESUMEN

El objetivo del presente trabajo fue determinar los efectos de las principales variables del secado por aspersión para la obtención de jugo de naranja en polvo como método alternativo para el aprovechamiento integral del jugo de naranja. Las variables evaluadas para el secado por aspersión fueron la temperatura de entrada del aire, flujo de alimentación y concentración de maltodextrina, las cuales tuvieron diferente grado de significancia sobre las respuestas evaluadas, siendo la temperatura de entrada de aire la que tuvo mayor grado de significancia sobre el contenido de humedad (p ≤ 0.01) y contenido de polifenoles (p ≤ 0.05), mientras que la concentración de maltodextrina lo fue para el rendimiento y humedad (p ≤ 0.05), sin embargo, en los atributos de color no se observaron efectos significativos bajo estas variables. Por tanto, utilizando secado por aspersión, se obtuvo un polvo de jugo de naranja con características fisicoquímicas estables, usando maltodextrina 7% (p/v) y alginato de sodio 0.1% (p/v) como agentes portadores, 160ºC de temperatura de entrada de aire, 14 mL/min de flujo de alimentación, lo que permitirá el uso de esta tecnología de secado.

KEYWORDS:

• Orange juice
• spray-drying
• physicochemical properties
• maltodextrin
• citrus

PALABRAS CLAVES:

• Jugo de naranja
• secado por aspersión
• propiedades fisicoquímicas
• maltodextrina
• cítrico

1. Introduction

The orange (Citrus sinensis L. Osbeck) is a citrus that is cultivated worldwide in the tropical, subtropical and some temperate zones. It is the most produced fruit in the world, and the one with the highest per capita consumption. Of the different types of orange, sweet orange varieties are the most important commercially. In Mexico, the variety with the highest commercial production is late maturing Valencia, with a production registered in 27 states, with a total area of 337,680 hectares (SAGARPA, 2012).

The orange is frequently consumed as fresh fruit. It is used generally in the preparation of juices, syrups, soft drinks, desserts, ice creams, and cakes. The offer that the Mexican citrus juice processing company offers is practically 90 thousand tons of concentrated orange juice; considering only the agroindustry located in the citrus grove that surrounds the Gulf of Mexico (Veracruz, Nuevo León, Tamaulipas, San Luis Potosí and Tabasco) and part of the Yucatan Peninsula. Concentrated orange juice is the most important in the world, both for the volume produced and the number of markets that consume it, the main centers of consumption of orange juice located in Europe and North America (Licona, 2009).

Therefore, this citrus has the potential to remain a competitive crop for the development of new products that allow the diversification of products made from this fruit and under a perspective of integral use; one of these technologies is encapsulation. An additional advantage is that an encapsulated compound gradually released from the compound that has englobed or trapped it and food products with better sensory and nutritional characteristics obtained (Yañez et al., 2002). The choice of encapsulation method that is carried out will depend on the size, biocompatibility, and biodegradability of the micro particles, physicochemical properties of the material, an application that will give and the cost of the process. In the food industry, different materials and methods used as carrier agents, among which are: carbohydrates, esters, gums, lipids, proteins, and inorganic materials. These encapsulation methods can divide according to Parra (2010) into mechanical and chemical processes, and one of the most important is spray-drying.

Spray drying is a method used to produce dry powder from a liquid by rapidly drying with a hot gas and it is mostly used in the food and pharmaceutical industries. Spray dryers can dry a product very quickly compared to other methods of drying and is suitable for heat sensitive products, since the exposure time at high temperatures it is short. Spray-drying is the transformation of a fluid (solution, dispersion or emulsion) into dry particles, it is a continuous process that involves a combination of several states, such as atomization, diffusion of the spray in air, evaporation, and separation of the product (Costa et al., 2015; Gharsallaoui, Roudautm, Chambin, Voilley, & Saurel, 2007; Sandoval, Cu, Peraza, & Acereto, 2016).

Gabas, Telis, Sobral, and Telis-Romero (2007) mention that submitting fruit juice to a spray-drying process provides a long storage life at ordinary temperatures, since drying the juice produces a stable product. However, the drying of fruit juices and other products with high sugar content presents technical difficulties due to its hygroscopicity and thermoplasticity at high temperatures and humidity. For this reason, spray-drying is a well-established and widely technique to transform liquid foods into powder form. In the spray-drying of fruit juices maltodextrins with different dextrose equivalents (DE) have been used, some examples of microencapsulated juices by spray-drying with maltodextrins are: watermelon juice with maltodextrins 9 DE (Quek, Chok, & Swedlund, 2007), pineapple juice with maltodextrin 10 DE (Abadio, Domínguez, Borges, & Oliveira, 2004), mango juice with maltodextrin 20 DE (Cano, Stringheta, Ramos, & Cal-Vidal, 2005) blackberry juice (Fang & Bhandari, 2012) and cactus juice with maltodextrin 6 DE (Lozano, 2009). The optimization of process of spray-drying using response surface methodology was used to obtain concentrated orange juice was evaluated by Pino, Aragüez, and Bringas (2018), inlet air temperature and maltodextrin content showed significant effect on all responses studied, obtained a highly acceptable juice powder with physical and chemical properties at inlet air temperature 155°C, maltodextrin content 74%.

A wide variety of materials can use as carrier agents, which must be food grade, biodegradable, and have a strong barrier between the internal and external phase. Among the carrier compounds are the maltodextrins, which are essential for the preparation of juices that are going to be spray dried, given that they are colorless, odorless and of low viscosity at high concentrations, as well as allowing the formation of free-flowing powders, without masking the original flavor (García, González, Ochoa, & Medrano, 2004). Sodium alginate, which is a natural polymer derived from marine algae, constituted by D-mannuronic and L-glucuronic acid units linked linearly by bonds. Alginates containing a large amount of glucuronic acid tend to form stiffer and more porous gels, while in contrast, those richer in mannuronic acid content tend to be softer gels. Alginate is the most used biopolymer in the food industry for the formation of matrices, due to its easy use, biocompatibility, low cost and safety (García & López, 2012).

The main cause of spray drying is to increase the shelf life and easy handling of juices. To achieve an effective drying and to obtain an acceptable product, drying conditions must be optimized (Shishir and Chen, 2017); the major optimized parameters are inlet air temperature, relative humidity of air, outlet air temperature, atomizer speed (Verma & Vir, 2013). Spray-drying has been used a technique to obtain orange juice powder using dehumidified air as drying medium (Goula & Adamopoulos, 2010; Khwanpruk, Akkaraphenphan, Wattananukit, Kaewket, & Chusai, 2018) and vacuum (Islam, Kitamura, Yamano, & Kitamura, 2016). Besides multivariable regression analysis to obtain models that show the relationship between operating spray dryer parameters and powder physical properties (Chegini & Ghobadian, 2005) has been evaluated, however, the results of these researches, the evaluated properties were very variable.

The objective of this work was to determine the effects of the main variables evaluated in spray-drying to obtain orange juice powder using maltodextrin and sodium alginate as carrier agents, to allow the development of alternative products for the commercialization of this citrus, as well as future applications of innovation in the agrifood sector.

2. Material and methods

2.1. Materials

Sweet oranges (Citrus sinensis L. Osbeck) Valencia variety obtained from local markets, which were washed and disinfected, before the extraction of orange juice (one orange juice liter obtained fifteen orange). The DE10 maltodextrin (MD) and sodium alginate from a national supplier (commercial Quial, S.A. Tepic, Mexico), both substances were used are carrier agents.

2.2. Characterization of orange juice

The concentration of total soluble solids was reported in Brix degrees (°Brix) and quantified with the refractometer (MR-90 Digital Refractometer); the pH value was measured using a digital pH meter (Thermo Scientific, Orion Products, USA) (AOAC, 2000).

The total titratable acidity was evaluated by titration with sodium hydroxide (0.1 N) and expressed as citric acid. The moisture content was determined according to (AOAC, 2000). The ash was estimated by introducing a previously weighed sample into a muffle furnace at 550°C to a constant weight, and the extract measured by the AOAC method (AOAC, 2000).

2.3. Spray-drying

The general procedure for the preparation of the suspensions of the orange juice for its encapsulation by spray-drying consisted of juicing using an extractor, filtering through a sieve No. 16, then the carrier agents (maltodextrin and sodium alginate) were dissolved, and the feeding was carried out, which placed in a 1 L test tube.

In all experimental treatments, a Minortm spray dryer was used for pilot scale production (GEA Niro A/S, Søborg, Denmark) with a cylindrical section of the drying chamber 1.2 m in diameter and 1.0 m in height for the spray-drying process. The conical section was 0.7 m in height with 0.3 m in the lower diameter outlet. The rotating disk atomizer has twenty-four annular holes of 4 × 3 mm in a disk of 18 mm thickness of 0.10 m in diameter (Chávez et al., 2016). The feed flow rates from 10, 12 and 14 mL/min controlled by a variable flow peristaltic pump (Watson Marlon, 504U) connected to a flexible plastic tube inside a container and a liquid inlet of the atomizer. The outlet temperatures varied from 80°C to 90°C, the atomizer speed from 20,000 rpm to 30,000 rpm and the air flow from 720 m³/h to 810 m³/h.

The inlet air temperature in the spray dryer varied to 120, 140, and 160°C. The powder products were in a receiver at the bottom of the drying chamber (large), and a receiver collected at the bottom of the cyclone (fine). Spray-dried powder samples were immediately sealed in their vacuum bags and weighed to prevent subsequent moisture absorption.

2.3.1. Characterization of microencapsulated orange juice with spray-drying)

Yields

Percent yields (%) were calculated using the ratio of the final weight of the powder obtained after spray-drying and the total weight of solids in the solution fed to the spray dryer according to Santiago et al. (2015)(Equation 1(1) $\mathrm{\%}\mathrm{Y}\mathrm{i}\mathrm{e}\mathrm{l}\mathrm{d}=\left[\left(\mathrm{W}\mathrm{e}\mathrm{i}\mathrm{g}\mathrm{h}\mathrm{t}\mathrm{o}\mathrm{f}\mathrm{p}\mathrm{o}\mathrm{w}\mathrm{d}\mathrm{e}\mathrm{r}\mathrm{o}\mathrm{b}\mathrm{t}\mathrm{a}\mathrm{i}\mathrm{n}\mathrm{e}\mathrm{d}\mathrm{a}\mathrm{f}\mathrm{t}\mathrm{e}\mathrm{r}\mathrm{s}\mathrm{p}\mathrm{r}\mathrm{a}\mathrm{y}-\mathrm{d}\mathrm{r}\mathrm{y}\mathrm{i}\mathrm{n}\mathrm{g}\right)\left(\mathrm{g}\right)/\left(\mathrm{T}\mathrm{o}\mathrm{t}\mathrm{a}\mathrm{l}\mathrm{w}\mathrm{e}\mathrm{i}\mathrm{g}\mathrm{h}\mathrm{t}\mathrm{o}\mathrm{f}\mathrm{i}\mathrm{n}\mathrm{i}\mathrm{t}\mathrm{i}\mathrm{a}\mathrm{l}\mathrm{w}\mathrm{a}\mathrm{l}\mathrm{l}\mathrm{m}\mathrm{a}\mathrm{t}\mathrm{e}\mathrm{r}\mathrm{i}\mathrm{a}\mathrm{l}\mathrm{a}\mathrm{n}\mathrm{d}\mathrm{o}\mathrm{r}\mathrm{a}\mathrm{n}\mathrm{g}\mathrm{e}\mathrm{j}\mathrm{u}\mathrm{i}\mathrm{c}\mathrm{e}\right)\left(\mathrm{g}\right)\right]\mathrm{x}100$(1) ):

(1) $\mathrm{\%}\mathrm{Y}\mathrm{i}\mathrm{e}\mathrm{l}\mathrm{d}=\left[\left(\mathrm{W}\mathrm{e}\mathrm{i}\mathrm{g}\mathrm{h}\mathrm{t}\mathrm{o}\mathrm{f}\mathrm{p}\mathrm{o}\mathrm{w}\mathrm{d}\mathrm{e}\mathrm{r}\mathrm{o}\mathrm{b}\mathrm{t}\mathrm{a}\mathrm{i}\mathrm{n}\mathrm{e}\mathrm{d}\mathrm{a}\mathrm{f}\mathrm{t}\mathrm{e}\mathrm{r}\mathrm{s}\mathrm{p}\mathrm{r}\mathrm{a}\mathrm{y}-\mathrm{d}\mathrm{r}\mathrm{y}\mathrm{i}\mathrm{n}\mathrm{g}\right)\left(\mathrm{g}\right)/\left(\mathrm{T}\mathrm{o}\mathrm{t}\mathrm{a}\mathrm{l}\mathrm{w}\mathrm{e}\mathrm{i}\mathrm{g}\mathrm{h}\mathrm{t}\mathrm{o}\mathrm{f}\mathrm{i}\mathrm{n}\mathrm{i}\mathrm{t}\mathrm{i}\mathrm{a}\mathrm{l}\mathrm{w}\mathrm{a}\mathrm{l}\mathrm{l}\mathrm{m}\mathrm{a}\mathrm{t}\mathrm{e}\mathrm{r}\mathrm{i}\mathrm{a}\mathrm{l}\mathrm{a}\mathrm{n}\mathrm{d}\mathrm{o}\mathrm{r}\mathrm{a}\mathrm{n}\mathrm{g}\mathrm{e}\mathrm{j}\mathrm{u}\mathrm{i}\mathrm{c}\mathrm{e}\right)\left(\mathrm{g}\right)\right]\mathrm{x}100$(1)

Moisture

The moisture content of the powder was determined by placing approximately 2 g of sample in an air oven at 100 ± 2°C for 2 to 3 h until constant weight and expressed in terms of the percentage of the wet base (Nollet, 2004).

Apparent density

The apparent density (g/mL) determined as described in Fazaeli, Emam-Djomeh, Ashtari, and Omid (2012) using 1 g of powder and placed in a 10 mL graduated cylinder, placed in a vortex (model VTX-5, CScientific) at 1000 rpm for 1 min. The density calculated by dividing the mass of the powder by the final volume occupied in the test tube.

Scanning electron microscopy (SEM)

SEM was carried out according to the method reported by Quiñones et al. (2011). The samples of orange juice powder were placed on a piece of copper with conductive tape and coated with gold at ten mbar for 90 s (model Desk II, Denton Vacuum, NJ, USA). They then observed in a scanning electron microscope (JEOL Mod. JSM6300 Jeol, Japan) at an accelerating voltage of 20 kV and magnified up to 1000x.

Color attributes

The color analysis of the obtained powders was carried out with a MiniScan EZ 45/0 LAV colorimeter (MSEZ1342) (Reston, VA, USA), Hunter Associates Laboratory HunterLab following the CIE-L*a*b* color system, where the value of L* (brightness) varies from black (0) to white (100), the value of chroma a* varies from green (−60) to red (+60) and the value of chroma b* varies from blue (−60) to yellow (+60). The chroma value C* and hue angle (H*), called the CIELCh color system, according to Minolta (1993), were calculated using Equations (2)(2) $\mathrm{C}\mathrm{r}\mathrm{o}\mathrm{m}\mathrm{a}\left(C\ast \right)={\left({\left(\mathrm{a}\ast \right)}^2+{\left(\mathrm{b}\ast \right)}^2\right)}^{1/2}$(2) and (3(3) $H\ast =\mathrm{t}\mathrm{a}{\mathrm{n}}^{-1}\left(\mathrm{b}\ast /\mathrm{a}\ast \right)$(3) ).

(2) $\mathrm{C}\mathrm{r}\mathrm{o}\mathrm{m}\mathrm{a}\left(C\ast \right)={\left({\left(\mathrm{a}\ast \right)}^2+{\left(\mathrm{b}\ast \right)}^2\right)}^{1/2}$(2)

(3) $H\ast =\mathrm{t}\mathrm{a}{\mathrm{n}}^{-1}\left(\mathrm{b}\ast /\mathrm{a}\ast \right)$(3)

Total polyphenol content

The total polyphenol content was evaluated using the Folin-Ciocalteu assay, as described by Aliakbarian, Casazza, and Perego (2011), using a UV–Vis spectrophotometer (Perkin Elmer, Wellesley, USA) at a wavelength of 725 nm. The results expressed in milligrams of gallic acid (GAE) per gram of dry powder (DP) (mgGAE/gDP).

2.4. Statistical analysis

The experiments were carried out using a factorial design of experiments 3³⁻¹ whose matrix of the different treatments to obtain orange juice powder using spray-drying shown in Table 1. The Excel program (Microsoft Office 2010) was used to determine the measures of central tendency and graphics, and the Statistica 7.0 software (StatSoft Inc., Tulsa, OK, USA) to establish differences between treatments using the method of multiple range tests of Least Significant Differences (LSD) and differences considered statistically significant when p ≤ 0.05 and p ≤ 0.01. All data were reported as mean ± standard deviation.

Table 1. Experimental design used to obtain orange juice powder with spray drying.

Tabla 1. Diseño experimental usado para obtener jugo de naranja en polvo con secado por aspersión

Treatment	Inlet air temperature (°C)	Feed flow (mL/min)	Maltodextrin concentration (% w/w)
1	120	10	3
2	120	12	7
3	120	14	5
4	140	10	7
5	140	12	5
6	140	14	3
7	160	10	5
8	160	12	3
9	160	14	7

3. Results and discussion

3.1. Characterization and physicochemical parameters of orange juice powder with spray-drying

The results of the physicochemical characterization of the natural orange juice are shown in Table 2. The moisture content of the orange juice was 89.89% and the ash content is a useful indicator of the content of minerals provided by the juice, obtaining values of 1.81%, whose concentration is lower than that reported by Akusu, Kiin-Kabari, and Ebere (2016) in orange juice (2.68%) and higher than pineapple juice (0.42%). The values of pH and acidity in the natural juice were 3.57 and 0.86 g/L of citric acid, respectively. Both parameters are related to the excellent stability of the juice, since acid pH decreases the bacterial action, although the development of molds and yeasts with a modest affectation. Acidity can play an essential role in the perception of fruit quality due to organic acid profiles can determine juice flavor, freshness or spoilage and are essential for their contribution to sensory attributes (Anvoh, Zoro-Bi, & Gnakin, 2009; Dafny-Yalin et al., 2010).

Table 2. Physicochemical characterization of natural orange juice.

Tabla 2. Caracterización fisicoquímica de jugo de naranja natural

Parameter	Natural juice
Moisture content (%)	89.89 ± 1.23
Ashes	2.50 ± 0.16
Total soluble solids (°Brix)	14.70 ± 0.98
pH	3.57 ± 0.01
Titulable acidity (g/L citric acid)	0.86 ± 0.05
Sweetness index	17.17 ± 0.38
Astringency index	0.06 ± 0.01
Color
L*	34.82 ± 0.97
a*	4.61 ± 0.28
b*	58.08 ± 1.19
C*	58.26 ± 1.17
H*	85.46 ± 0.37

The concentration of soluble solids in the orange juice was 14.70°Brix associated with the presence of dissolved sugars and other solutes present in the juice, which agrees with a low sweetness index (17.17) (Table 2), since that according to Wardy, Saalia, Steiner-Asiedu, Budu, and Sefa-Dedeh (2009), juices with sweetness indexes higher than 19 are considered sweet and not very acid. However, in commercial juices, low values of sweetness index can be found, which vary from 1.70 to 11.10 (Ndife, Awogbenja, & Zakari, 2013). The juice astringency index was 0.06, a value considered low. This organoleptic parameter is associated with the concentration of acids, and together with the sweetness index, it is used for the prediction of the predominant flavors in the juices.

In the color attributes showed in Table 2, the value of H* was high (85.46), very close to 90, a characteristic of a yellow hue and the value of C* was also high (58.26) which combined with an intermediate value of L* (34.82)(value of 0 indicates a black tone and value of 100 indicates a white tone). This demonstrated that the juice had an intense distinctive yellow color that resulted in the appreciation and acceptance of the freshness of the juice by the consumers. It is also a relevant criterion for quality control during the commercial classification of the product. The values found in this study were similar to those reported by Niu et al. (2008) for the same variety of orange. Therefore, for an effective spray-drying to obtain a product with acceptable physicochemical properties, drying conditions must be evaluated.

Table 3 shows the effect of the evaluated variables on the physicochemical properties of orange juice powder, obtained by spray-drying. The inlet air temperature significantly affected the moisture content (p ≤ 0.01) and the total polyphenol content (p ≤ 0.05). Figure 1a shows the behavior of the moisture content, which was decreasing as the inlet air temperature increased, with the highest values observed at the lowest temperature evaluated (120°C), similar effects were observed in orange juice by Khwanpruk et al. (2018) and Pino et al. (2018) where moisture content was negatively affected by high inlet air temperature (above 155°C). The highest moisture content reduction in the juice powder obtained at 160°C, with a feed flow of 14 mL/min.

Table 3. Effects of main variables of spray-drying on orange juice powder.

Tabla 3. Efectos de las principales variables del secado por aspersión sobre el jugo de naranja en polvo

	Inlet air temperatura (°C)	Feed flux (mL/min)	Maltodextrin concentration (% w/w)
Yield (%)	NS	NS	*
Apparent density (g/cm^3)	NS	*	NS
Moisture content (%)	**	NS	*
Total polyphenol content (mg/L)	*	NS	NS
Luminosity (L*)	NS	NS	NS
Croma (C*)	NS	NS	NS
Hue° (H*)	NS	NS	NS

*p ≤ 0.05 **p ≤ 0.01 NS: No significant

Figure 1. Effect of feed rate at 10 mL/min (□), 12 mL/min (∆) and 14 mL/min (◊) and inlet air temperature on water content (a) and apparent density (b) of orange juice powder.

Figura 1. Efecto del flujo de alimentación a 10 mL/min (□), 12 mL/min (∆) and 14 mL/min (◊) y temperatura de entrada del aire sobre el contenido de humedad (a) y densidad aparente (b) del jugo de naranja en polvo

The feed flow had a significant effect on the apparent density (p ≤ 0.05), as can be seen in Figure 1b. It observed that, as the feed flow increased, the density increased, reaching the highest values (0.49–0.54 g/cm³) at a flow of 14 mL/min, while with the lowest feed flow evaluated, the lower density values were obtained (0.32–0.38 g/cm³). This behavior is because when increasing the feed flow, smaller drops of juice form, which when increasing the temperature is allowed quick elimination of the water in the form of vapor, leaving a porous surface inside the capsule of solids that are forming during its exit. Which, together with the lower moisture content, would allow the powdered particles to hydrate and solubilize faster in water, and this behavior had previously observed by Jumah et al. (2000).

The process conditions considered in this study strongly influenced the characteristics of the powdered particles as reported by other authors (Cal & Sollohub, 2010; Costa et al., 2015). These authors point out that the type and size of the powdered particles should also be considered, the nozzle of the atomizer as well as the rotation speed of the atomizing disk, in addition to the physicochemical properties of the material atomized. Chegini and Ghobadian (2005) reported that in powdered particles of orange juice, low values of atomizer velocity and air inlet temperature, caused particles to present low values of apparent density (0.34 to 0.85 g/cm³) and a high moisture content, associated with high wettability values, which causes yield losses due to the accumulation of material on the walls of the drying chamber (Oliveira & Petrovick, 2010).

In Figure 2, the effect of the concentration of maltodextrin, at different drying conditions, on the properties of the orange juice powder is shown. In Figure 2a, it was observed that the highest yield was (71.5%) when using 7% maltodextrin, with air inlet temperature 120°C and feed flow 10 mL/min (p ≤ 0.05). The increase in yield was due to the higher content of soluble solids in the dehydrated samples, since the powdered particles with 5 and 7% maltodextrin, with higher yield values, had lower moisture content (Figure 2c). The moisture content was also associated with higher apparent density values (higher weight per volume) (Figure 2b), and the samples heated at 140 and 160ºC presented lower moisture content values and presented higher apparent density values. In concentrated orange juice, powder yield and ascorbic acid retention increased with the rise in maltodextrin content, while moisture content was negatively affected by maltodextrin content, according Pino et al. (2018).

Figure 2. Effect of spray drying conditions on the main physicochemical parameters of orange juice powder at different maltodextrin concentration (% w/w): 3 (□), 5 (■) and 7 (■). ^a,b,cDifferent letters indicate significant differences (p ≤ 0.05) in maltodextrin concentrations. ^A,B,CDifferent letters indicate significant differences (p ≤ 0.05) in maltodextrin concentration regardless of feed flow and inlet air temperature.

Figura 2. Efecto de las condiciones del secado por aspersión sobre los parámetros fisicoquímicos del jugo de naranja en polvo a diferentes concentraciones de maltodextrina (% m/m): 3 (□), 5 (■) y 7 (■). ^a,b,cLetras distintas muestran diferencias significativas (p ≤ 0.05) en las concentraciones de maltodextrina. ^A,B,CLetras distintas muestran diferencias significativas (p ≤ 0.05) en las concentraciones de maltodextrina independientemente del flujo de alimentación y temperatura de entrada del aire

The moisture content of the powdered particles decreased (p ≤ 0.05) by increasing the concentration of maltodextrin, at the three drying temperatures (Figure 2c), suggesting that maltodextrin facilitates the diffusion of water molecules in the vapor state towards the outer of the particles. Which prevents the adhesion of the particles to the walls of the drying chamber and reduces its hygroscopicity, since the soluble solids present in fruit juices, mainly low molecular weight sugars and organic acids, have low temperatures of glass transition, are highly hygroscopic and can easily absorb moisture from the surrounding air (Shrestha et al., 2007). It causes problems of adhesion to the walls of the drying chamber and low fluidity, and therefore, lower yields (Sathyashree, Ramachandra, Udaykumar Nidoni, & Nagaraj, 2018).

The incorporation of maltodextrin increases the glass transition temperature of the juices, besides protecting against chemical or physicochemical damage in some bioactive compounds present in the juice such as polyphenols, increasing the stability and shelf life of the final product. There are several studies in which maltodextrin has been added to preserve fruit juices by spray-drying. Abadio et al. (2004) used concentrations of 10 to 15% (w/w) maltodextrin to preserve pineapple juice and found that the lower concentration of the added solute presented better solubility. In the juice of blackberry and fruit Gac (Momordica cochinchinensis) concentrations of maltodextrin of 5-7% and air inlet temperature of 140-150°C preserving antioxidant activity of the product. (Kha, Nguyen, & Roach, 2010).

On the other hand, Gong, Zhang, Mujumdar, and Sun (2007), reported that concentrations of 17% maltodextrin are required to improve the efficiency of blackberry juice drying. Mango juice required conditions of air temperature at 165°C, and higher maltodextrin concentrations (12 to 21%) to obtain lower moisture content in comparison of orange juice (Cano, Stringheta, Barbosa, Fonseca, & Silva, 2011). In pure guava, the use of 15% maltodextrin and air inlet temperature of 150°C allowed the best quality properties of the microencapsulated (Shishir, Taip, Aziz, & Talib, 2014). It is also essential to consider that the physicochemical properties of microencapsulated products depend both on the concentration of the maltodextrin and their degree of dextrose equivalents (Goula & Adamopoulos, 2010).

Figure 2d shows polyphenol was affected significantly (p ≤ 0.05) by the air inlet temperature, better preserving these compounds when using drying temperature of 160ºC. The use of 5 and 7% of maltodextrin increased the polyphenol stability and has been reported, that can remain stable for long periods of time (Khazaei, Jafari, Ghorbani, & Kakhki, 2014).

The color of the orange juice powder is crucial since it determines the color of the reconstituted juice. In this study, it was observed that the color profile varied according to the concentration of maltodextrin and the process conditions (Figure 3). The treatment containing 7% maltodextrin and processed with inlet air at 160°C and flow of 14 mL/min showed the most significant color affectation, increasing its values of L* and H*, which is associated to lighter yellow color; whereas the values of C* decreased, indicating loss of color intensity.

Figure 3. Color attributes of orange juice powder obtained with spray-drying with different maltodextrin concentration (% w/w): 3 (□), 5 (■) y 7 (■). ^a,b,cDifferent letters indicate significant differences (p ≤ 0.05) in maltodextrin concentrations. ^A,B,CDifferent letters indicate significant differences (p ≤ 0.05) in maltodextrin concentration regardless of feed flow and inlet air temperature.

Figura 3. Atributos de color del jugo de naranja en polvo obtenido con secado por aspersión con diferentes concentración de maltodextrina (% p/p): 3 (□), 5 (■) y 7 (■). ^a,b,cLetras distintas muestran diferencias significativas (p ≤ 0.05) en las concentraciones de maltodextrina. ^A,B,CLetras distintas muestran diferencias significativas (p ≤ 0.05) en las concentraciones de maltodextrina independientemente del flujo de alimentación y temperatura de entrada del aire

Despite of having the most considerable change in the attributes of color, the orange juice powder presented the best physicochemical properties (Table 4), with a high yield (63.68%) and apparent density (0.5 g/cm3), the lowest moisture content (2.40%) and the highest polyphenol content of 573.8 mg/L, which is relevant because these components are natural bioactive compounds that have very vital biological activities. As their antioxidant activity, and according to Peterson et al. (2006), in citrus flavonoids there is one of the most prestigious groups of polyphenols, predominating flavanone glycosides such as narirutin, hesperidin, naringin, and neohesperidin.

Table 4. Physicochemical properties of orange juice powder using spray drying at 160°C air inlet temperature, 14 mL/min feed flow and 7% w/w maltodextrin concentration.

Tabla 4. Propiedades fisicoquímicas del jugo de naranja en polvo utilizando secado por aspersión a 160°C temperatura de entrada del aire, 14 mL/min flujo de alimentación y 7% p/p concentración de maltodextrina

Variables	Results
Yield (%)	63.68
Moisture content (%)	2.40 ± 0.14
Apparent density (g/cm^3)	0.50 ± 0.01
Total phenolic content (mg/L)	573.83 ± 6.26
Color attributes
L*	86.22 ± 0.32
a*	4.49 ± 0.51
b*	26.69 ± 1.13
C*	27.07 ± 1.20
H*	80.46 ± 0.66

It is shown in Figure 4, the distribution of the orange juice powdered particles from treatment 9 are shown in different extensions a) 30 µm and b) 5 µm, mainly identifying spherical and hemispherical morphologies. Some powdered particles showed some irregularity, rough surfaces and small pores, possibly caused to the high temperatures and evaporation rate of water (160°C), causing the agglomeration and the formation of more porous and fragmented structures. This same behavior has been found in other studies of drying techniques with maltodextrin, using different juices and infusions (Santiago et al., 2015; Tonon, Brabet, & Hubinger, 2009).

Figure 4. SEM images of orange juice powdered particles at different magnifications at a) 30 µm and b) 5 µm.

Figura 4. Imágenes de MEB de partículas de jugo de naranja en polvo a diferentes ampliaciones a) 30 µm y b) 5 µm

4. Conclusion

The results obtained in this study demonstrate that spray-drying as drying method to obtain orange juice powdered using conditions sodium alginate 0.1% (w/w), maltodextrin 7% (w/w) at 160°C inlet air temperature and 14 mL/min feed flow, allow to obtain a powder with desirable physicochemical characteristics, with lower moisture content, which represents an alternative for its commercialization, to diversify uses or incorporation as ingredient in food, pharmaceuticals and cosmetic products.

Acknowledgments

The first author thanks the Higher Education Undersecretary and the General Directorate of Higher Education University for the grant awarded for the implementation of research project DSA/103.5/16/10526 within the program of Bachelor of Nutrition of the Autonomous University of Tamaulipas. As well as the company PROCIMART for the technical support for the realization of the work.

Disclosure statement

The authors reported no potential conflict of interest.

Additional information

Funding

This work was supported by the Subsecretaría de Educación Superior [DSA/103.5/16/1052], specifically it was obtained from Apoyo a la Incorporación de Nuevos PTC obtained from PRODEP México.