Spray drying of elderberry (sambucus nigra l ) juice to maintain its phenolic content

To increase the recovery percentage during the drying process, the elderberry juice was spray dried with five different wall materials, i.e., soya milk powder, soya protein powder, isolat

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Spray Drying of Elderberry (Sambucus nigra L.) Juice to Maintain Its Phenolic Content

Ramesh Murugesan a & Valérie Orsat a a

Department of Bioresource Engineering, Faculty of Agricultural and Environmental Sciences , McGill University , Sainte-Anne-de-Bellevue, Quebec, Canada

Published online: 19 Oct 2011

To cite this article: Ramesh Murugesan & Valérie Orsat (2011) Spray Drying of Elderberry (Sambucus nigra L.)

Juice to Maintain Its Phenolic Content, Drying Technology: An International Journal, 29:14, 1729-1740, DOI:

10.1080/07373937.2011.602485

To link to this article: http://dx.doi.org/10.1080/07373937.2011.602485

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Spray Drying of Elderberry (Sambucus nigra L.) Juice to

Maintain Its Phenolic Content

Ramesh Murugesan and Vale´rie Orsat

Department of Bioresource Engineering, Faculty of Agricultural and Environmental Sciences, McGill

University, Sainte-Anne-de-Bellevue, Quebec, Canada

Spray drying was studied with Elderberry (Sambucus nigra L.)

juice using a Buchi B-290 spray dryer Different inlet temperatures

ranging from 70
C to 120
C and two feed flow rates of 180 ml/hr

and 300 ml/hr were considered for the experiment The operating

parameters were optimized in terms of total phenolic content

reten-tion, color, and powder recovery The inlet temperature of 80
C

with feed flow rate of 180 ml/hr gave high phenolic content retention

with good color but lower recovery of the dried powder, i.e., less

than 50% To increase the recovery percentage during the drying

process, the elderberry juice was spray dried with five different wall

materials, i.e., soya milk powder, soya protein powder, isolated soya

protein, gum acacia, and maltodextrin Wall materials were

evaluated in terms of total phenolic content retention, color of the

powder, and mass recovery percentage The gum acacia and

malto-dextrin gave better results and high recovery percentage, i.e., more

than 70% The best three combinations were stored under three

dif-ferent storage conditions in three difdif-ferent packagings to monitor

the stability of the phenolic content and color of the powder

Keywords Antioxidants; Color measurement; Fruit powder;

Polyphenols; Recovery

INTRODUCTION

Large quantities of fruits and vegetables are produced

worldwide; however, due to their large water content, they

are prone to microbial contamination and

chemical-enzymatic reactions, which lead to spoilage of these fresh

commodities.[1] Due to their perishable nature,

post-harvest losses of fruits and vegetables are higher when

compared to pulses and cereals To reduce the losses due

to the microorganism’s deterioration, the moisture content

or water activity of the food products must be brought to a

safer, lower level

Drying generally refers to the removal of moisture from

materials During the drying process, the moisture level of

the product is brought down by evaporation or

subli-mation or any other moisture migration phenomenon

Drying of food materials is the best method for storing products for longer periods as compared to other preser-vation methods and it is widely used,[2]even though drying processes are the most energy-consuming preservation methods.[3]

The spray-drying process is one of the drying processes, which is used not only for drying purposes but also used for encapsulation, and many food manufacturing processes use spray drying to convert liquid food products such as juices into a powder form.[4] Most food industries, especially dairy industries, use spray drying as a preser-vation technique to increase the storability of the products

by reducing water activity Spray drying is also used in the pharmaceutical industry to dry heat-sensitive materials and

to enhance the flow properties of the dried powder materi-als.[5,6] Spray-drying food process applications have con-tributed significantly in our daily lives We use a lot of products which have been manufactured by spray drying such as fruit powders, instant coffee, milk powder, powdered cheese, instant soups, sweeteners, etc.[7]

Spray drying is one of the most commonly used encap-sulation techniques by the food industry[8,9]and one of the oldest known methods, since the 1930s, to encapsulate fla-vors using gum acacia.[10]Because of its energy efficiency, relative ease of operation, and minimal process duration, spray drying is considered as an alternative to freeze drying and can be used for larger-scale productions with readily available equipment in the market.[11,12] The main benefit

is that spray drying can be useful to produce stable and functional products.[6,13] Due to the short contact times with heat during spray drying, higher amounts of the func-tional properties such as flavor, color, and other nutrients are retained in the final products.[14,15]

From an engineering point of view, we can describe spray drying as an effective process which converts a fluid feed into its powder form in a single operation.[16] The spray dryer converts fluid feed into solid particles by spray-ing them into a hot air dryspray-ing medium The spray-dryspray-ing process generally consists of several stages involving atomi-zation, mixing of spray and drying gas, evaporation, and

Correspondence: Vale´rie Orsat, Department of Bioresource

Engineering, Faculty of Agricultural and Environmental Sciences,

21111 Lakeshore Road, Macdonald Campus, McGill University,

Sainte-Anne-de-Bellevue, Que´bec, Canada H9X 3V9; E-mail:

valerie.orsat@mcgill.ca

ISSN: 0737-3937 print=1532-2300 online

DOI: 10.1080/07373937.2011.602485

1729

separation.[6]The spray-drying process is a process that has

complex equipment interactions, process parameters, and

product parameters that have a significant effect on the

final product quality The final product quality mainly

depends upon the spray dryer operating parameters.[17]

Spray drying is an important drying process to produce

powders and it mostly produces amorphous materials

rather than crystalline materials.[18] The production of

crystallites is principally dependent upon the drying

conditions, i.e., inlet air temperature, pressure, etc.[19]

The main objective of drying fruit juices is to produce a

material which has higher shelf life with higher stability

along with ease of handling.[16] The spray-drying process

produces a good quality final product with low water

activity and reduced weight, resulting in easier storage

and transportation The final product’s physicochemical

properties mainly depend on feed flow rate, particle size,

viscosity, spray dryer temperature, pressure, and type of

atomizer.[20] Spray-drying processed materials can be

classified into sticky products and non-sticky products.[4]

Spray drying is often selected as it can process material

very rapidly while providing control of the particle size

distribution.[21]

Often carriers or wall materials are used in spray drying

to minimize the damage to the functional components such

as polyphenolic compounds, vitamins, minerals, etc Gum

acacia and maltodextrin are well known and commonly

used wall materials or carriers in drying of fruit juices

Gum acacia is an efficient encapsulating material because

of its high water solubility, lower viscosity, and capability

of oil-in-water emulsification.[22,23] Gum acacia is a

com-plex polysaccharide that mainly contains galactose,

arabi-nose, rhamarabi-nose, glucuronic acids, and a smaller fraction

of protein,[24–26]and this protein content governs the

func-tional properties of gum acacia.[27] A lot of research has

been conducted using gum acacia for its encapsulation

functionality.[28–33]

Maltodextrin is a popular encapsulating material next to

gum acacia Maltodextrin is mostly added to reduce the

stickiness during the spray-drying process as the addition

of maltodextrin increases the glass transition

tempera-ture.[4]Maltodextrin consists of a chain of D-glucose units

connected with glycosidic bonds (1!4).[34]

Maltodextrins are classified as a function of the length of the chain

expressed as Dextrose Equivalents (DE) ranging between

3 and 20 Maltodextrin with various dextrose equivalents

has been used to spray dry a variety of fluids such as

mango, blackcurrant, apricot, and raspberry.[1,31,35]

Proteinous compounds such as soya milk powder,

soya protein powder, skim milk powder, etc., are also

used by some researchers[1,5] to find alternative wall

mate-rials or partially replace carriers like gum acacia as gum

acacia is costly and market supplies are at times

unpredictable

Elderberry fruit belongs to the wild berry category and

is predominantly grown in Europe and North America Elderberries have been traditionally used for medicinal purposes Elderberries have been reported useful for the treatment of many diseases like asthma, colds, consti-pation, arthritis, etc.[36]As a food, elderberries are mainly used for the production of juice and concentrates; however, they are also used to manufacture syrup, wine, jelly, pie filling, desserts, cakes, candies, etc.[36]

The color pigments derived from elderberry can be used

in many food commodities and beverages as coloring agents and nutritional supplements The color pigments from elderberry have high anthocyanin content[37] and the anthocyanin content in elderberry fruit is higher than

in strawberries and bilberries Elderberry has a high antho-cyanin content of 863 mg=l.[38] The elderberry’s antho-cyanin belongs to the category of cyanidin anthoantho-cyanins Cyanidin-3-sambubioside and cyanidin-3-glucoside are the two major anthocyanins in elderberry and contribute around 85% of the total anthocyanins present in the fruit,[39]making them an attractive nutritional supplement

in many foods Spray drying is an ideal process to produce

an elderberry powder with high nutritional and color functionality

Elderberry juice was spray dried in this study to produce elderberry powder of high quality In this study, three soya products were tested along with other well-known carriers like maltodextrin and gum acacia to understand the effi-cacy of these materials in preserving the phenol content and color of elderberry juice Soya milk powder, isolated soya protein, soya protein powder, gum acacia, and maltodextrin were used as carriers in the spray-drying experiment

MATERIALS AND METHODS Elderberry Juice Preparation The fully ripened elderberry fruits were manually har-vested in 2009 from a farm located in Franklin, Quebec, Canada Harvested elderberry fruits were immediately transported to the laboratory and manually cleaned by running cold water to remove any dirt and foreign materi-als The fruits were stored at refrigeration temperature (4
C) before juice extraction

The total soluble solid content of the fruit was used as

an indicator for the fruit maturity Fully ripened fruits were carefully selected for the juice extraction The fruits were brought up to room temperature before juice extraction

A commercial juice extractor was used to extract the juice from the thawed fruits The extracted juice was filtered twice using muslin cloth to remove seeds and skin particles The juice was spray dried immediately without any delay The total soluble solids content of the fruit juice ranged from 10 to 13
Brix and pH ranged from 3.9 to 4.1

Reagents and Standards

Sodium Carbonate (anhydrous), Folin–Ciocalteu

reagent, Gallic acid (anhydrous), and de-ionized water

were required in this experiment All reagents and

chemi-cals used in the experiment were of analytical quality and

purchased from Fisher Scientific International, Inc

Wall Materials

Five wall materials were tested: Spray dried gum acacia

(also known as gum arabic) from Importers Service

Corpor-ation, New Jersey, USA; Malto-dextrin (Excelvin1with DE

of 4-7) from Distrivin, Quebec, Canada; Isolated soya

pro-tein from Bob’s Red Mill natural foods, Milwaukee, USA;

Soya protein powder (purely bulkTM), and Soya milk

pow-der (purely bulkTM) from Verve Naturals, Guelph, Canada,

were used as wall materials in the experiment

All wall materials used in the research were tested in

terms of their interactions with the polyphenols present

in the fruit juice All wall materials were added at the total

juice solids to wall materials ratio of 5:1, 5:2, 5:3, 5:4 and

1:1 (weight basis) The wall materials were blended with

fruit juice using an electric blender for 10 min of

homo-genizing for all samples The homogenized juice was spray

dried immediately without any delay

Spray Drying Equipment

A laboratory mini spray dryer (Buchi – B290) was used

in the experiment This laboratory spray dryer had the

dry-ing capacity of 1 kg H2O=hr The maximum inlet

tempera-ture that can be used with this spray dryer is 220
C The

minimum atomizing pressure requirements of the spray

drying process using this laboratory spray dryer range from

58 bars This range was adopted from the manufacturer

specification from Buchi Corporation Various particle

sizes can be produced from the spray dryer according to

the operating pressure and atomizer flow speed The unit

was operated at 5.5 bars atomizer pressure with an

aspir-ation gas flow rate of 35 m3=hr, while the feed flow was

operated at either 180 or 300 ml=hr

Total Phenolic Content (TPC) Determination

The phenolic content of the spray-dried powder was

measured by recommended Folin-Ciocalteu’s method.[40]

The total polyphenolic content estimation method was

used in the experiment without doing any modification of

the method The absorbance was measured at 765 nm using

a spectrophotometer (BIOCHROM – Ultrospec 1000TM)

1 gram of fruit powder was used in each analysis

Deionized water was used as a dissolving medium The

whole experiment was carried out at room temperature

Gallic acid was used as a standard for the validation and

the results were correlated with a standard Gallic acid

curve, which has a standard linear correlation coefficient

(R) of 0.9997 and the results were expressed in milligram equivalents of Gallic acid (GAE) per g of spray-dried elderberry powder

Color Measurement Color of spray-dried powder was measured using a chromameter (MINOLTATM) 1 g of the fruit powder was used to measure the color The chromameter works with the principle of measuring reflected light and express-ing in three coordinates L, a, b Light beam from the chromameter was passed through the powder and the reflected light was measured by using L, a, b coordinates The L value indicates the darkness or lightness of the product The a value indicates redness or greenness, while the b value designates yellowness or blueness of the sample The hue angle is an indicator that denotes the exact color of the material The hue angle denoted ranges

of color starting from dark red color to light magenta

in the color axis The hue angle was calculated from the following formula:

Hue angle¼ tan1ða=bÞ

Mass Recovery Percentage Determination Recovery percentage of the spray-drying process was calculated by mass balance The initial dry matter in the juice, with and without wall materials, was determined by hot air oven A known quantity of juice was dried in the oven at 120
C for 24 hours to quantify initial dry matter

100 ml of the fruit juice was spray dried for each experi-ment The spray-dried powder weight was measured at the end of each trial and total mass recovery percentage during the spray-drying process was calculated using the following formula:

Mass recovery %¼

(Initial dry mater in juice(g)

 (Leftover powder mass

in spray dryer (g)) Initial dry matter in juice (g)

 100

The leftover mass of powder in the above formula indi-cates the powder, which was not recovered during the spray-drying process In other words, this is the powder that was sticking to the drying chamber and other parts

of the dryer

Actual Phenol Content (APC) Determination

To evaluate each wall material, as an encapsulating material, a new parameter named actual phenol content was used The actual phenol content is a parameter depen-dent of mass recovery percentage and total phenol content

This parameter was calculated to determine the actual

efficiency of the wall material as the mass recovery

percent-age and total phenol content depend on the type of wall

materials and their ratio to total solid content of the juice

The actual phenol content was calculated using the

following formula:

Actual phenol content, (mg GAE/g)¼ Total phenol;

ðmgGAE=gÞ  Mass recovery percentage ð%Þ

Statistical Analysis

All the experiments were conducted in three replicates

Mean values of the replicates are presented A two-way

Analysis of Variance (ANOVA) was carried out with the

confidence level of 95% (P 0.05) to determine the

signifi-cant effect of using different wall materials and their ratio

to total solid content of the juice in the spray-drying

process SAS (Windows version 9.2) software was used

for the statistical analysis and Microsoft Excel (Windows

version 12) was used to interpret the results

Storage Studies

The best three combinations of different wall materials

in terms of total phenol content of spray-dried powder

were stored in three different storage conditions with three

different packagings for 90 days, to study the stability of

the phenolic content and color of the powder The three

storage conditions were as follows:

a Room temperature (20
C) with light (1739 lux) –

(LRT)

b Room temperature (20
C) without light (dark) –

(DRT)

c Refrigerated (5
C) without light (dark) – (REF)

and three packaging material as follows:

a paper bag

b polythene bag

c polythene bag – vacuum packed

At the end of the storage period the samples were

ana-lyzed for total phenol content and color The values were

compared with the original values

RESULTS AND DISCUSSION

Optimization of Inlet Temperature and Feed Flow Rate

The inlet temperature and feed flow rate of the spray

dryer were optimized for elderberry juice drying All other

spray-dryer parameters, such as aspiration gas flow rate

and air pressure, were not changed during the experiment

These values were reported in section 2.4 The spray drying

equipment has no control over outlet air temperature Six

inlet temperatures, i.e., 70, 80, 90, 100, 110, and 120
C,

and two feed flow rates, i.e., 180, 300 ml=hr, were tested

To optimize the feed flow rate and temperature, the spray-drying experiment was carried out for all possible combinations The flow rate and the inlet temperature were optimized based upon the total phenolic content of the fruit powder The total phenolic content was measured as per the method mentioned in section 2.5 The loss of the phenolic content increased with the increase of inlet tem-perature For example, the total phenols content in elder-berry powder spray dried at 120
C was around 10% lower when compared to control but it was only 6% lower with the inlet temperature of 100
C at the feed flow rate of

180 ml=hr (Table 1)

These results are in accordance with previous research,[41]which observed that the total phenolic content

of wild elderberry did not change significantly during the juice concentration process at the temperature of 40
C; however, they found significant loss (25%) of phenolic con-tent during blanching at a temperature of 70
C for

10 min.[41] This significant 25% loss is likely due to the thermo-sensitivity of the fruit juice and the high tempera-ture maintained for longer duration In the case of spray drying, our fruit juice was subjected to a higher tempera-ture; however, for only a few seconds, which may lead to

a reduced loss in the phenolic content of the juice Mass recovery percentage was calculated for each experiment and the results were interpreted Generally, mass recovery percentage was decreased with increase of feed flow rate at the same air inlet temperature For example, at 120
C the recovery percentage was 48.11% in

180 ml=hr flow rate but it was decreased to 38.97% in

300 ml=hr feed flow rate The lower mass recovery percent-age was mainly caused by stickiness of the product It might be as a result of inefficient moisture removal during

300 ml=hr as the heat input per ml of feed input was lower when compared to 180 ml=hr Table 1 presents overall changes in total phenolic content due to feed flow rate and inlet temperature Similarly, results were reported for the spray drying of chicory root inulin,[18]where the mass recovery of the spray drying was decreased with an increase

of feed flow rate, with lower air inlet temperature In that

TABLE 1 Optimization of inlet temperature and feed flow rate

Mass recovery, % Inlet

temperature,
C

Loss of phenol content, % 180 ml=hr 300 ml=hr

study, they achieved only 6.2% recovery at 142
C inlet

tem-perature; however, increasing the inlet temperature to

198
C, to increase the heat input to the feed load, resulted

in 30.7% mass recovery for the same feed flow rate.[18]

These results were in accordance with findings of the

current research

The 80
C inlet temperature at 180 ml=hr inlet flow rate

gave better phenolic content retention and color with,

how-ever, lower mass recovery percentage than at higher

tem-perature In this combination, the loss of phenolic

content was around 2.65% with a recovery of 42.34%

However, at the same inlet temperature, i.e., 80
C, with

300 ml=hr feed flow rate resulted in a recovery of only

34.2% Hence the feed flow rate was fixed to 180 ml=hr

for the rest of the experiment, to ensure product recovery,

with an inlet temperature of 80
C to ensure phenol content

retention All wall material experiments were conducted

with 180 ml=hr feed flow rate and 80
C inlet temperature

Spray Dried Elderberry Powder Properties – Total

Phenolic Content

Phenolic compounds in fruits and vegetables are vastly

distributed and they provide color and flavor to fruits

and vegetables.[42] Polyphenols can provide good

antioxi-dant activity and help to prevent various cancer and

cardiovascular diseases However, polyphenols are a group

of antioxidants highly sensitive to degradation at high tem-peratures.[43]For example, high-temperature drying versus low-temperature drying has been shown to significantly influence the loss of the polyphenolic content in plums.[44] Similar results were obtained with drying of red grape pomace.[45]Grape peels dried at 140
C and 100
C experi-enced greater loss in polyphenolic content when compared

to peels dried at 60
C Similar results were also reported with sorghum.[46] Hence, it is very important to control process temperature, such as drying medium input tem-perature, to preserve a material’s total phenolics during processing

The study of the total phenol content in spray-dried elderberry juice as a function of wall materials is presented

in Figure 1 The highest phenolic content was found at 1:1 ratio of gum acacia with 48.1 mg GAE=g while the lowest phenolic content was found at 5:1 ratio of gum acacia with 35.2 mg GAE=g The total phenolic content of the elder-berry powder, obtained using maltodextrin as wall material, showed a different trend when compared to gum acacia The phenolic content did not increase in all cases with the increase of maltodextrin concentration For example, the phenolic content increased with the ratio increase from 5:1 to 5:2 but it decreased for ratio changes from 5:2 to 5:3 (Table 2) In general, the gum acacia pro-duced better phenolic content retention when compared

to maltodextrin and all other soya products

Similar findings were reported in many studies; for example, gum arabic and rice starch, along with gelatin, were used as encapsulating materials for ascorbic acid.[47] The inlet and outlet temperatures of the spray drying were maintained at 150
C and 80
C, respectively Gum arabic encapsulated ascorbic acid appeared to be more stable and produced better morphology as compared to rice starch encapsulated ascorbic acid and it showed higher retention, even in higher relative humidity as compared

to rice starch encapsulation

In another study, gum acacia and soluble poly-saccharides had good oxidative resistance when used as encapsulating materials to encapsulate arachidonic acid with ascorbic acid The spray drier inlet and outlet temperatures

FIG 1 Total phenolic content in spray-dried powder with different wall

materials.

TABLE 2 Percentage increase or decrease of total phenolic content of fruit powder with the increase

of concentration of wall materials Concentration

increment

Soya milk powder

Soya protein powder

Isolated soya protein

Gum acacia Maltodextrin

were set at 200
C and 100–110
C.[48]The spray

encapsula-tion of bixin, a pro-carotenoid found in annatto (Bixa

orellana L.), was studied[49] with air inlet and outlet

tem-peratures maintained at 180
C and 130
C Gum arabic

was a better encapsulating materials over maltodextrin as

it was 3 to 4 times more stable than maltodextrin For

lino-leic acid encapsulation, gum acacia performed better when

compared to maltodextrin in terms of encapsulation

efficiency, size, stability, and oxidation resistance.[50]

Published research has even suggested to use a mixture

of gum acacia and maltodextrin for better encapsulating

properties For example, cardamom oleoresins were

encap-sulated using gum arabic, maltodextrin, and modified

starch and showed that 4=6, 1=6, 1=6 proportion blends

can all effectively encapsulate the material However,

gum arabic was found to be the better wall material as

compared to other wall materials when all are used

alone.[51] The inlet and outlet temperatures of the spray

dryer were maintained at 178 2 and 120  5
C For

pep-per oleoresin encapsulation, gum arabic was the best

encapsulating material over modified starch in an

experi-ment where the inlet and outlet temperatures were

maintained at 178 2 and 110  5
C.[52]

As presented in Figure 1, we can clearly visualize the

increase of the phenolic content as the ratio of fruit juice

to wall material changed from 5:1 to 1:1 However, the

per-centage increase of phenolic retention was not uniform

(Table 2) Interestingly, the increase of some wall material

concentrations even decreased the phenolic content when

compared with immediate lower concentration of same

wall material For example, the increase in maltodextrin

concentration from 5:2 to 5:3 reduced the phenolic content

of the final fruit powder by 3.23%

Soya products results were different from gum acacia

and maltodextrin results For example, the total phenolic

content retention of the spray-dried powder increased with

increasing soya protein powder concentration, until a

maximum was reached, after which the total phenolic

content started decreasing with the increase in wall material (Figure 1) The total phenolic content was around 35.3 mg GAE=g of fruit powder at the wall material ratio

of 5:1 and it increased to up to 38.6 mg GAE=g of fruit powder with the total solids to wall material ratio of 5:3 and the percentage increase was around 4% in each case (Table 2) However, the total phenolic content decreased with the further increase of wall material beyond 5:3; for example, the phenolic content of the fruit powder decreased from 37.6 to 36.2 mg GAE=g with total solids

to wall material ratio of 5:4 and 1:1, respectively This indi-cates that there is a maximum quantity of soya protein powder that can be added to yield a benefit in the phenolic content retention

Similarly, when using isolated soya protein as a carrier, the increase in phenolic content was rapid from 5:1 to 5:2 with a jump from 36.3 mg GAE=g to 40.1 mg GAE=g of fruit powder; however, beyond the 5:3 ratio, the total phe-nolic content of the fruit powder remained almost stable at the value of 43 mg GAE=g of fruit powder This further supports that there is a maximum concentration of wall material that brings an increase in phenolics retention and that an increase of concentration of isolated soya pro-tein beyond the 5:3 ratio (to 5:4 or 1:1) may only bring a very minimal increase in the total phenols retention in the fruit powder

In summary, the current study indicates the potential use of soya products as an alternative to gum acacia and maltodextrin for the retention of phenolics during spray drying Among the soya products tested, soya milk powder and isolated soya protein powder produced better retention

of phenolic compounds when compared to soya protein powder Nonetheless, gum acacia gave the highest yield

in phenolic content retention

Spray-dried Elderberry Powder Properties – Powder Color (L Value and Hue Angle)

Anthocyanins are the compounds responsible for the red

or purple color of fruits.[53] The major anthocyanins present in elderberry are all cyanidin glycosides, which mostly include 3-sambubioside, 3-glucoside, 3-sambubio-side-5-glucoside and 3,5-diglucoside The anthocyanin content ranges from 200 to 1000 mg= 100 g fresh weight[54] and among these pigments 3-sambubioside were found to

be more stable when compared to other pigments in elder-berry fruit.[55] Like most polyphenols, anthocyanins are sensitive to temperature The anthocyanin content in blue-berries was significantly decreased during high-temperature drying.[56]Plums (Prunus domestica) were dried in an oven with different temperatures (55, 75, and 95
C) and dur-ation combindur-ations It was found that the drying process adversely affected the anthocyanin content of the fruit and its final color.[42]

FIG 2 L value of spray-dried powder with different wall materials.

In the current study, the color of the powder was

mea-sured using a chromameter and the values were presented

in terms of ‘‘L,’’ ‘‘a,’’ and ‘‘b.’’ The darkness of the powder,

expressed by the L value, is presented in Figure 2 Lower L

value indicates darkness while a higher L value indicates

lightness of the material The hue angles were calculated

using ‘‘a’’ and ‘‘b’’ color values and are presented in

Figure 3 All the wall materials diluted the color of the

powder Isolated soya protein produced lowest L value

found at ratio of 5:1 while the highest L value was found

with maltodextrin at 1:1 ratio The L value increased with

the increase of the wall material concentration In each case

the lowest L value was found at lowest concentration of the

wall material (5:1) and highest L value was found at the

highest wall material concentration (1:1) The highest

change or increase in L value (10.47%) was found with

mal-todextrin when the concentration increased from 5:1 to 5:2

The decrease in darkness of the powder is higher for all

soya products as compared to gum acacia and

maltodex-trin However, the decrease in the darkness of fruit powder

was not necessarily an indicator of loss of quality, but

rather an indication of a dilution effect from the wall

mate-rials For example, the highest L value (thus lighter color)

was found at 1:1 ratio of maltodextrin, while its total

phe-nol content was 41.4 mg GAE=g of powder, an average

retention value This indicates that the L value could not

solely be used as a quality indicator of the powder

The hue angle of the powder was calculated with a and b

values and the hue angle of the powder increased with the

increase of concentration of the wall material (Figure 3)

The lowest hue angle was found at 5:3 ratio of

maltodex-trin and the highest was found at 1:1 ratio of soya protein

powder A less pronounced increase in the hue angle with

the concentration increase of wall material was found with

maltodextrin The hue angle value stayed at around 270

regardless of increase in concentration of maltodextrin

This indicates that the maltodextrin had negligible effect

on the hue angle of the fruit powder

In the group of soya products, the soya milk powder and soya protein powder affected the hue angle significantly when compared with isolated soya protein The hue angle behaved in a more erratic manner when using isolated soya protein as a wall material The hue angle initially decreased with the ratio increase from 5:1 to 5:2; however, beyond the 5:2 ratio, the hue angle increased with an increase of the concentration of the isolated soya protein powder On the other hand, soya protein powder, soya milk powder, and gum acacia increased the hue angle with the increase

of their concentration (Figure 3)

Spray-dried Elderberry Powder – Mass Recovery Percentage and Actual Phenolic Content Recovery The mass recovery percentage using gum acacia was significantly affected by the wall material concentration (Figure 4) The highest mass recovery was found at 5:1 ratio with a percentage recovery of 80.1% and the lowest was found at 1:1 ratio with 72.8% These values are far better than for all wall materials from the soya origin (soya milk powder, isolated soya protein, and soya protein pow-der) Nonetheless, the mass recovery percentage increased following the same pattern where the recovery percentage decreased with the increase of wall material (gum acacia) concentration

The mass recovery percentage of spray-dried powder with maltodextrin was highest when compared to all other wall materials tested in the experiment The highest recov-ery was around 82% found at the ratio of 5:4 and the low-est recovery was found at 5:2 ratio with 77.9% Due to its high mass recovery percentage, the total phenol recovery was high when maltodextrin was used as a wall material The actual recovery in terms of total phenol of the elder-berry powder was calculated by multiplying the mass recovery percentage with the total phenol content of the elderberry powder (Figure 5) The highest actual phenol content was found at the ratio of 5:4 with 34 mg GAE=g

FIG 3 Hue angle of spray-dried powder with different wall materials.

FIG 4 Mass recovery percentage of spray-dried powder with different wall materials.

of fruit powder and the lowest phenol content of 31.2 mg

GAE=g of fruit powder was found at the ratio of 5:1

(Figure 5)

All soya products expressed a decrease in mass recovery

with an increase in their concentration With soya milk

powder, the highest recovery of 68.9% was obtained at

the lowest ratio of 5:1 (total juice solids: wall material)

The main reason for lower mass recovery percentage is

due to the stickiness of the soya products Thus, an increase

in wall material concentration increased the stickiness of

the spray-dried powder The fruit=wall material powder

tends to stick to the walls of the drying chamber and

cyclone, which leads to a lower product recovery The

high-est phenol content was only 27.2 mg GAE=g in actual

recovery, which is much lower, namely 40.74% when

com-pared to the original phenolic content of 45.9 mg GAE=g of

fruit powder This lower recovery prevents the use of the

soya milk powder as a wall material for elderberry juice

spray drying Similar results were obtained for the other

soya products Due to the lower mass recovery, the actual

phenolic content was low and resulted in a total phenolic

content of less than 23.9 mg GAE=g of fruit powder This

indicates that the soya protein powder or isolated soya

pro-tein did not adequately assist the drying of elderberry juice

as it decreased the efficiency of the drying by increasing the

stickiness of the elderberry powder

Overall Impact and Significance of Wall Material and

their Concentration on Total Phenolic Content,

Recovery, and Color Parameters (L, a, B)

The two-way ANOVA results are presented in Tables 3–

7 testing the significance of the wall materials and their

combinations as their effect varied with according

responses For example, the choice of wall material was

not a significant factor in the total phenol content retention

while the ratio of the wall material to total solids was

significant (P < 0.01) In general, the combination of wall

FIG 5 Actual phenolic content in spray-dried powder with different

wall materials.

TABLE 3 Two-way ANOVA – Total phenol content versus product

ratio and wall material

Ratio 4 186.295 46.5738 11.28 0 Wall material 4 25.692 6.423 1.56 0.234

TABLE 4 Two-way ANOVA – Recovery versus product ratio and

wall material

Ratio 4 332.93 83.233 4.24 0.016 Wall material 4 2165.2 541.299 27.56 0

TABLE 5 Two-way ANOVA – L-color versus product ratio and

wall material

Wall material 4 77.981 19.4953 14.12 0

TABLE 6 Two-way ANOVA – a-color versus product ratio and

wall material

Wall material 4 26.796 6.699 12.82 0

TABLE 7 Two-way ANOVA: b-color versus product ratio and

wall material

Wall material 4 63.7885 15.9471 29.59 0

material and their ratio were the deciding factors affecting

the recovery percentage (P < 0.05), and color values

(P < 0.01)

Storage Stability of the Total Phenol Content and Color

of Spray-Dried Elderberry Powder

The spray-dried elderberry powders were stored under

three different storage conditions and packed in three

dif-ferent packing materials as described in section 2.10 The

spray-dried powders were stored to monitor the stability

of total phenolic content and color Only three wall

materi-als were considered for the storage studies, namely gum

acacia, maltodextrin, and soya milk powder

These wall materials and their ratio were selected from

the spray-drying experiment Best actual phenolic content

of the spray-dried powder was used as a deciding factor

for choosing the wall materials and their ratios The

selec-ted ratio of total solids to wall materials were for gum

aca-cia, 1:1; for maltodextrin, 5:4; and for soya milk powder,

1:1 (Total solids: wall material)

All the samples were kept in storage for ninety days The

initial phenolic content and color parameters L, a, b were

measured After ninety days the final phenolic content

and color parameters were measured and compared with

the initial values

Total Phenol Content

The changes in the total phenolic content during storage

are presented in Figure 6 Gum acacia had the best results

followed by maltodextrin in phenolic content retention

during storage The lowest loss in phenolic content of

1.8% was found under the vacuum packing stored under

refrigerated condition (REF) using gum acacia as a wall

material On the other hand, the soya protein powder

resulted in the highest decrease in phenolic content with

29.2% loss found in the polythene packing stored in

presence of light

For gum acacia, all the packing stored at room tempera-ture with presence of light (LRT) showed higher loss with 14.6% for polythene packing and 10.6% for vacuum pack-ing, while the paper packing showed a lower decrease in phenolic content with only 5.3% This lower decrease might

be due to the lower light penetration into the spray-dried powder through the paper opacity

Physical appearance in terms of granulation and powder flowability in the fruit powder was assessed visually Dur-ing the storage period, the elderberry powder did not become sticky and maintained its free-flowing nature This indicates that the gum acacia did not have any adverse effects on the spray-dried powder in terms of lumps’ formation or stickiness

With maltodextrin fruit powder, the polyethylene and vacuum packings, stored under light at room temperature conditions, showed lower loss in phenolic content when compared to the respective packing types with gum acacia fruit powder Interestingly, the highest loss in phenolic con-tent was found in paper packing, which was stored with absence of light, indicating that contact with oxygen was the most important factor affecting the decrease in phenolic content for the maltodextrin spray-dried powder rather than degradation due to light Even though, the maltodextrin showed results similar to gum acacia (second best in terms

of phenolic retention), the physical character of the powder was not equivalent to the gum acacia spray-dried powder as

it became sticky and lumpy with loss of its free-flowing nature during the storage period at room temperature (with

or without light); however, this behavior did not occur in the powder stored under refrigerated condition with polythene packing This implies that the maltodextrin can be used to spray dry the elderberry juice, but the final product should

be stored under refrigerated condition with polythene pack-ing to prevent cakpack-ing of the powder

Soya milk powder did not produce better results when compared to maltodextrin and gum acacia Regardless of packing type and storage conditions, the soya-based pow-der expressed high decrease in phenolic content when com-pared to the other two wall materials during the storage period The percentage losses in phenolic content ranged from 7.7 to 29.2% (Figure 6) The highest decrease in phe-nolic content of 29.2% was found in the polythene packing stored in presence of light The physical character of the spray-dried powder with soya milk powder was poor and the spray-dried powder lost its free-flowing nature during the storage period The caking of the spray-dried powder was found in all storage conditions regardless of packing material This indicates that the elderberry juice spray dried with soya milk powder could not be adequately stored Powder Color – L Value and Hue Angle

Following storage, the L value was measured and the hue angle was calculated from the a and b color values

FIG 6 Total phenolic content (TPC) for different wall materials

following storage.