CHEMICAL ENGINEERING TRANSACTIONS  
 

VOL. 57, 2017 

A publication of 

 
The Italian Association 

of Chemical Engineering 
Online at www.aidic.it/cet 

Guest Editors: Sauro Pierucci, Jiří Jaromír Klemeš, Laura Piazza, Serafim Bakalis 
Copyright © 2017, AIDIC Servizi S.r.l. 

ISBN 978-88-95608- 48-8; ISSN 2283-9216 

Production of Chocolate Powdered Beverage with Enhanced 
Instant Properties 

Bahar Aliakbarian*a, Alessandro A. Casazzaa, Angelo Nanib, Patrizia Peregoa 
aDepartment of Civil, Chemical and Environmental Engineering, Genoa University, Via Opera Pia, 15, 16145 Genoa, Italy  
bDomori S.r.l., Via Pinerolo, 72/74,10060 None, Turin, Italy  
bahar.aliakbarian@unige.it 

Instant properties of chocolate powder such as solubility and dispersibility are important factors for the quality 
and consequently consumer acceptance of the final powdered beverage. With the aim of producing a novel 
powdered chocolate beverage with enhanced instant solubility, we studied the effect of spray drying process 
on the components of the chocolate powder. Spray drying of chocolate beverage formulation (complete recipe 
provided and protected by Domori s.r.l., Italy) was performed using a mixture of cocoa powder and sucrose 
30:70 (w/w). Liquid feed was prepared by dissolving 17.5 g of powder in 100 mL of deionized water at 60 °C 
and mixed until complete homogenization. The solution was fed to a mini spray dryer B-290 (Büchi, 
Huddersfield, UK). In this work an inlet temperature of 150 °C was used. Maltodextrin concentration (0, 3.5 
and 7 % w/w) and drying air flow rate (22, 27 and 32 m3/h) were varied. Powders were stored at 4 °C in closed 
dark vessels before analysis. 
The results of full factorial design showed that operating at a drying air flow rate of 27 m3/h and a maltodextrin 
concentration of 3.5 % w/w, powder with solubility of 74.2 ± 6.8% and dispersibility of 58.7 ± 2.9% was 
achieved. At this operative condition, powder recovery yield was almost consistent with the industrial one 
(45.5 ± 2.5%). Therefore, spray drying presents a useful way to produce chocolate powder with better instant 
solubility, which can also be dissolved in less amount of water (70 mL instead of 120 mL). 

1. Introduction 

For several years, the powdered beverage manufacturing has been considered one of the slowest growing 
food industries worldwide (Shittu and Lawal, 2007). Developing niche and healthy products as well as 
increasing the knowledge about product formulation are necessary to overcome this trend. Unfortunately, 
sufficient information about the effect of physical properties and chemical composition of the ingredients on 
the final characteristics of the beverage is at present scanty in the literature. Among the powdered drinks, 
instant hot chocolate plays an important role. Usually, this product mainly consists of milk, cocoa, sugar, 
emulsifier and small amount of flavours. Instant properties of chocolate powder, such as wettability and 
solubility, characterize the quality of the end use instant beverage and, as a consequence, of the consumer 
acceptance. According to the definition given by Schubert (1993), instant beverages are based on 
agglomerated powders that are supposed to be completely dissolved or dispersed in the specific amount of 
liquid (e.g. water or milk) after stirring for a short time. A good instantized beverage has no floating particles on 
the surface nor sediment at the bottom of the container after minimum stirring. The high fat content (10-25%) 
of the cocoa powder is one of the reasons which affects the wettability of the instant product (Wieland, 1972). 
The other factor can be attributed to the capillary structure of cocoa powder, which could obstacle the water 
penetration by trapping air pockets (Omobuwajo et al., 2000). To overcome those drawbacks, agglomeration 
has been considered as major factor to enhance the solubility of chocolate powder drink (Omobuwajo et al., 
2000) since it increases the particle size thus shortening wetting time. However, not all the agglomeration 
processes (agglomeration of wetted single particles, agglomeration by drying, combination of both these 
methods, and agglomeration by compression) resulted in good instant solubilisation. The agglomerate size 
and structure should be characterized by high porosity (Kyaw Hla and Hogekamp, 1999), good dispersibility 
(Schubert, 1993) and also acceptable strength for handling and packaging (Hogekamp et al., 1996). 

                               
 
 

 

 
   

                                                 
DOI: 10.3303/CET1757147

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Please cite this article as: Aliakbarian B., Casazza A.A., Nani A., Perego P., 2017, Production of chocolate powdered beverage with enhanced 
instant properties, Chemical Engineering Transactions, 57, 877-882  DOI: 10.3303/CET1757147 

877



Spray drying represents an alternative process to improve the reconstitution properties of chocolate powder 
beverage. Spray drying is the most widely used commercial method for food drying processes, giving a high 
quality powder product with enhanced instantaneous solubility with relatively low cost (Paini et al., 2015). 
Working with very short time of heat contact and high rate of evaporation, this process ensures the nutritive 
value of the components. Maltodextrin is one of the most commonly used carriers in the process of spray 
drying due to its high solubility in water (Cano-Chauca et al., 2005). To the best of our knowledge, the use of 
spray drying and maltodextrin as carrier has not been vastly investigated for the preparation of chocolate 
powdered beverage. As is evidenced throughout the world, the demand of novel and healthy foods is growing. 
For this reason, the aim of this study was to produce a novel chocolate powdered beverage with enhanced 
instantized properties, which can be dissolved completely in lower amount of water (70 mL) compared to the 
traditional quantity (about 120 mL). Effect of spray drying operative parameters such as drying air flow rate, 
the concentration of maltodextrin and its effect on the physico-chemical and instantizing properties of main 
components of the chocolate drink were investigated.   

2. Materials and methods 

2.1 Reagents and ingredients  

Cocoa and sucrose powders were kindly furnished by the Italian company Domori s.r.l.. Maltodextrin (16.5-
19.5 dextrose equivalents), acetic acid, methanol and acetonitrile (HPLC grade) were purchase from Sigma-
Aldrich (Milan, Italy).  

2.2 Spray drying process 

We used spray drying process to produce soluble chocolate powders. Spray drying of chocolate beverage 
formulation (recipe provided and protected by Domori s.r.l., Italy) was performed using a mixture of cocoa 
powder and sucrose 30:70 (w/w). Liquid feed was prepared by dissolving 17.5 g of powder in 100 mL of 
deionized water at 60 °C and mixed until complete homogenization. The solution was fed to a mini spray dryer 
B-290 (Büchi, Huddersfield, UK). Spray dryer was run with water for 10 min before and after each experiment. 
In this work an inlet temperature of 150 °C was used. Preliminary studies performed in our laboratory indicated 
that an inlet temperature lower than 130 °C causes the formation of a wet film on the walls of the chamber, 
while a temperature higher than 160 °C leads to an excessive denaturation of the product (Aliakbarian et al., 
2015a; Paini et al., 2015). Maltodextrin (MD) concentration and drying air flow rate ranges were selected 
based on literature review and taking into account the minimum alteration of the product sample (Cano-
Chauca et al., 2005; Jinapong et al., 2008;). In experimental design tests, aspiration rate was changed from 
22 to 32 m3/h and different percentages (0, 3.5 and 7% w/w) of MD were added to the initial formulation, 
reducing the sucrose percentage from 70 to 66.5 and 63.0 %, respectively. Powders were stored at 4 °C in 
closed dark vessels before analysis. 

2.3 Powder characterization  

Powder recovery yield (%) after spray drying process was defined as the ratio of the mass of powder 
recovered from the cyclone to the solids originally presented in the feed solution. We did not consider powder 
attached to the heating vessel as part of the yield because of the very dark color and the burned aspect. The 
moisture content of the spray dried samples, expressed as percentage, was calculated based on the weight 
loss of the sample (0.5 g) after drying at 105 °C for 6 h. Solubility, as an important instant property of the 
powder, was determined based on the method described by (Shittu and Lawal, 2007) with some modifications. 
Briefly, approximately 2.0 g of each sample were mixed with 20 mL of water at 80 °C and stirred for 30 min. 
The suspension was then centrifuged (ALC PK131, Alberta, Canada) at 9500 rpm for 10 min and the 
supernatant was collected. The weight of the solids in the supernatant after drying at 105 °C was used as the 
solubility index and expressed as percentage of solubility in water. For dispersibility index, about 10.0 g of 
each powder were used. Samples were manually stirred with 100 mL of water at 27 °C for 1 min. The 
suspension was maintained firmed for 30 min. Fifty millilitres of the supernatant containing dispersed solids 
were separated and weighed. The dispersibility index expressed as the percentage was calculated using the 
following equation (Eq(1)). 

𝐷𝑖𝑠𝑝𝑒𝑟𝑠𝑖𝑏𝑖𝑙𝑖𝑡𝑦 (%) = 2 ∗ (((𝑀2 − 𝑀1))/𝑀0) ∗ 100) (1) 

Where, M2 is the weight of 50 mL of supernatant (g), M1 is weight of 50 mL of distilled water (g), and M0 is 
the powdered sample (g) (Shittu and Lawal, 2007). Scanning electron microscopy (SEM 515, Philips, 
Netherlands) was used to evaluate the microstructure of the particles. Appropriate amounts of powders were 

878



coated with a 30 nm-thick gold layer and observed in secondary electrons (5.0 kV) at 300x magnification. In 
order to quantify the sugar and cocoa percentages in the spray dried powder, the sucrose after spray drying 
process was analysed by HPLC. For the analysis a HPLC 1100 (Hewlett Packard, Palo Alto, USA) equipped 
with a Hi-Plex H column (300 x 7.7 mm) (Phenomenex, Torrance, CA, USA) was used following the 
methodology described by (Aliakbarian et al., 2015b). The mobile phase was 0.5% v/v of sulfuric acid 1 M in 
Milli-Q water, the flux was set at 0.5 mL/min and the column temperature was set at 50 °C. Before the 
injection, 1.0 g of spray dried sample was dissolved in 100 mL of hot water (70 °C), mixed for 30 min and 
centrifuged at 10000 rpm for 10 min. The sucrose concentration was evaluated comparing the peak sequence 
and intensity to a 0.5 g/L sucrose standard solution. The cocoa powder percentage in the product was 
theoretically calculated using the following equation (Eq. 2): 

Cocoa (%) = 100 – sucrose (%) – MD (%) (2) 

2.4 Statistical analysis  

All the experiments were carried out in triplicate (n = 3). ANOVA and Tukey's post hoc test (p < 0.05) were 
used (“Statistica 10.0”, StatSoft, Tulsa, USA). 

3. Results and discussions 

Table 1 shows the matrix design of the independent variables according to the 32 full factorial design and the 
experimental results. In every sample, the moisture content resulted in being less than 7% (almost in the 
acceptable range supporting microbiological stability). The highest moisture content was achieved using the 
maximum air drying flow rate (32 m3/h) and MD concentration (7% w/w). This moisture content can be 
attributed to the protecting effect of MD as coating agent by interpolating more quantity of water in the 
particles. 

Table 1: Full factorial design matrix and the responses of the dependent variables 

Runs  
 

Independent variables Responses 
X1 X2 Recovery (%) Moisture (%) Solubility (%) Dispersibility (%) 

1 22.0 0.0 18.3±1.7b 2.9±0.01f 66.0±5.2a 67.8±0.1b,d 
2 27.0 0.0 44.2±2.5a 0.0±0.03b 75.0±7.8a 54.4±1.2a 
3 32.0 0.0 45.4±4.1a 3.6±0.05a 69.0±10.1a 43.0±4.1c 
4 22.0 3.5 33.2±3.2c 1.0±0.04c 75.5±8.9a 23.8±0.9e 
5 27.0 3.5 45.5±2.5a 4.9±0.02g 74.2±6.8a 58.7±2.9a,b 
6 32.0 3.5 49.2±5.2a 2.0±0.03d 78.0±11.2a 56.5±4.7a 
7 22.0 7.0 23.3±1.7b 2.7±0.06e 73.0±12.5a 58.4±3.4a,b 
8 27.0 7.0 48.2±4.8a 3.5±0.08a 72.0±11.4a 74.5±5.6d 
9 32.0 7.0 45.2±3.4a 6.7±0.09h 74.5±13.8a 40.8±3.2c 
       

X1: Drying Air flow rate (m3/h); X2: Maltodextrin concentration (% w/w). Different letters within the columns indicate 
significant difference between data at p < 0.05. Data are expressed as mean value ± standard deviation, n = 3. 

 
As concern the solubility, powders showed good solubility properties, with values ranging from 66 % (without 
addition of MD) to 78 % when 3.5 % w/w of MD was used. Addition of higher quantity of MD did not increase 
the solubility of the powders (p<0.05). Regard to the dispersibility index, using an intermediate air drying flow 
rate (27 m3/h), the increase of the concentration of MD from 0.0 to 7.0 % w/w enhanced this property of the 
final product up to 37.02%. Results of regression analysis demonstrated that the drying air flow rate 
significantly influenced (p<0.05) the recovery yield of the powdered product (Figure 1). For this reason, the 
effect of those variables has been studied using response surface modelling (RSM). RSM, as a combination of 
statistical and mathematical techniques, enables the evaluation of different parameters and their interaction on 
response variables (De Faveri et al., 2007). This methodology has been widely used for the optimization of 
food processes such as olive oil (Aliakbarian et al., 2008), chocolate-flavored and peanut soy beverages 
(Deshpande et al., 2008) and winery industry (Casazza et al., 2012). 
Statistical prediction revealed that at critical values of drying air flow rate and MD concentration of 29.65 m3/h 
and 4.0 % w/w, respectively, the powder recovery yield will be maximum and equal to 54.43%. At this 
condition, working with reasonable amount of drying aid, the recovery yield is industrially acceptable (Abad 
and Turon, 2012). 

879



 

Figure 1: Response surface of powder recovery yield (%) as a simultaneous function of drying air flow rate 

(m
3
/h) and maltodextrin concentration (% w/w) (Recovery (%) = -314.00 + 24.26 X1-0.41 X12 + 3.39 X2 - 0.42 

X22). 

SEM images were used to evaluate the effect of MD concentration and the drying air flow on the structure of 
the microparticles. Figure 2 shows the presence in all systems of hexagonal particles (sucrose) among 
spherical ones, whether or not the addition of MD. In the presence of 3.5% w/w of MD and 27 m 3/h of drying 
air flow (Fig. 2 b), the particles showed a good degree of uniformity without strong adhesion among them. This 
can be due to the crystallization effect of spray drying in the presence of MD as a carrier to induce this 
phenomenon (Cano-Chauca et al., 2005). While aggregation of the particles has been noted in the samples 
containing 7% w/w of MD (Fig. 2 c, and f). This aggregation was more evident with a drying air flow equal to 
32 m3/h (Fig. 2 f). This result is validated by the moisture content (6.66%) in these samples as well. Such a 
result could be due to the greater quantities of water that can be entrapped inside high amounts of drying 
agent, which generates bigger particles. The same behavior was also noticed by Paini et al. (2015) in the 
spray drying of olive pomace extract using MD concentration of 500 g/L and 10 mL/min of feed flow at 150 °C. 
At this condition, the authors observed bigger microparticles than the ones obtained with 100 g/L of MD 
(keeping the same operative conditions). When they used 100 g/L of MD, 99% of the microcapsules showed a 
diameter range less than 20 μm, while with 500 g/L of MD only 29% were in the same range of dimension. 

880



 

Figure 2: SEM images (300x) of the particles obtained by spray drying at inlet temperature of 150 °C varying 

maltodextrin (MD) concentration (0.0%, 3.5 and 7.0 w/w) and drying air flow (27 and 32 m
3
/h). Images on top 

(a, b, and c) refer to drying air flow of 27 m
3
/h. Images on the bottom (d, e, and f) refer to drying air flow of 3

2
 

m
3
/h. C: cocoa, S: sucrose. 

To assess the effect of spray drying process on the final chocolate powder formulation, we calculated the 
sucrose percentage by HPLC before and after the drying process.  
As can be seen in Figure 3, the change in sucrose percentage was more evident in the samples without MD 
with an increment of 7, 13, and 7% at an air flow of 22, 27, and 32 m3/h, respectively when compared to 
sample A (before the drying process). Moreover, a notable increment of sucrose compared to the sample 
before spray drying (C) was noticed (16%) using 7% w/w of MD and 22 m3/h of drying air flow. The best 
results were obtained using 3.5% w/w of MD. In this condition and varying the drying air flow, the content of 
sucrose remain almost the same as the initial composition before spray drying (1% of difference was noticed 
with respect to sample B).  
Considering the sucrose percentage in the products and taking into account the hypothesis that MD will be 
totally recovered after the spray drying process, the content of cocoa resulted to be notably decreased in 
samples without the addition of MD and in the one containing 7% of MD spray dried at 22 m3/h. The variation 
of cocoa quantity in the final product can cause unpleasant taste and as consequence consumer 
dissatisfaction. 
 

 

Figure 3: The composition percentage of the product containing principally sucrose and cocoa powder and 

maltodextrin as a carrier quantified by HPLC. In the spray drying process maltodextrin was varied from 0 to 

7% w/w and drying air flow from 22 to 32 m
3
/h. Samples A, B and C are analyzed before spray drying process. 

881



4. Conclusions 

The approach taken in this study was to exploit the effect of spray drying process on instant properties of 
chocolate powder beverage. We demonstrated the ability of producing particles with good solubility (more than 
70%) and dispersibility (higher than 50%) remaining in an acceptable industrial range of product yield (around 
50%) and moisture content (less than 6%). The use of maltodextrin resulted to protect the composition of 
spray dried component (when operating at 27 m3/h as drying air flow) producing uniform and separate 
particles. These findings can be potentially used in powder beverage production industries to enhance the 
solubility properties. 

Acknowledgments 

The authors wish to thank Dr. Alberto Lagazzo for his support and help for SEM imaging. 

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