INTRODUCTIONDehydration of food allows extending its shelf lifeby reducing the chemical and microbial activities [1].Drying reduces the moisture content of powder, whichguarantees a long and safe storage [2]. High-watercontent makes fruit juices highly perishable productswith high transportation costs. In this regard, powderedfruit juices are an attractive option for the food business:they are stable, space-effective, and easy to transport [3].Atomization, droplet-hot air interaction, and moistureevaporation are the three essential processes of spraydrying[4].Fruits usually undergo such procedures as opensun-drying, hot air drying, solar drying, microwavedrying,freeze-drying, and spray-drying. However,these methods have some disadvantages. For example,hot air drying is time-consuming, and freeze-drying israther expensive [5, 6]. Spray-drying is a highly suitableprocess for heat-sensitive products producing powderswith good quality [7–9]. Spray-dried powders have gooddispersion characteristics and are easy to incorporateinto food products [10]. Some resent studies introducedspray-dried powders from cempedak jackfruit and kuinimango [11–13].Spray-drying is an effective means of makinginhalable powders [3]. The list of physicochemicalparameters that affect powders during spray-dryingincludes such process factors as viscosity, particlesize, liquid feed flow rate, temperature and pressureof the drying air, the kind of atomizer, etc. As a result,optimizing the drying process is critical for obtaininggoods with improved sensory and nutritional properties,as well as for increasing process yield. Studies thatfeature surface characteristics of powder particles canprovide better knowledge of the production process andoptimize the powder composition [4].236Pui L.P. et al. Foods and Raw Materials. 2022;10(2):235–251Effective spray-drying requires a careful selectionof operating conditions. For particles ≤ 2 μm, spraydryinghas a poor cyclone collection efficiency. Acommon spray-dryer has an average output of 20–50%,but a new high-performance cyclone developed by theSwiss company BÜCHI increased it to ≥ 70%. Anothersignificant problem with spray-drying is the lack ofcontrol over the mean droplet size. As a result, dropletscome in a wide range of sizes, and pneumatic nozzlescan cause clogging. Ultrasonic nozzles produce moreconsistent droplets and more uniform size distribution ofthe powder [7, 8].Some difficulties, such as stickiness, hygroscopicity,and solubility, can be overcome by introducing thecarrier agents before atomization. Biopolymersand gums are the most popular carrier agents.These compounds are typically associated withmicroencapsulation. They can minimize powder hygroscopicity,protect delicate food components fromunfavorable ambient circumstances, reduce foodcomponent volatility and reactivity, and improve theappearance of the finished product [10].Fruit storage provides their off-season supply.However, some fruits tend to rot during storage and losetheir nutritional content. The benefits of a dried extractover traditional liquid forms include cheaper storagecosts, increased concentration, and active componentstability. Spray-drying can produce powders withprecise quality criteria in a continuous process [14]. Itis a one-stage technology that turns liquid meals orsuspensions into powder form. Spray-drying is also usedin pharmacy for tablet coating. Spray-drying has threeprimary steps: (1) atomizing the liquid feed, (2) creatingand drying the droplets, and (3) droplet motion.Problem statement. Spray-dried fruit juice powdershave high sugar solids content and usually assumeamorphous state [14]. Some recent studies describethe advances in the spray-drying of sugar-rich foods,including fruit juices, pulp, and honey with or withoutcarriers [15]. Products with low molecular weightsugars, e.g. fructose, sucrose, and glucose, have a verylow glass transition temperature. Sucrose, glucose,and fructose have the glass transition temperature of62, 32, and –5°C, respectively. They reduce the glasstransition temperature of sugar-rich foods, which areprone to caking during storage [16]. The hygroscopicand thermoplastic nature of dried materials, such asfruit juice powders, are known to cause adhesion todryer walls, reduce the drying yield, increase stickiness,and decrease solubility [17]. These sugars are veryhygroscopic, which increases their stickiness andtendency to agglomeration [18].Organic lactic, malic, tartaric, and citric acids alsomake spray-drying difficult. When tartaric, citric, andmalic acids were applied at concentrations of ≥ 10% drymatter, they reduced the powder recovery. As a result,spray-drying of fruits with high acid content requiredmore maltodextrin [19]. Spray-drying below +20°C ofglass transition temperature helped avoid stickinessbut was not economically feasible [20]. Spray-driedblood fruit powder was found to have high solubilityand good retention of resveratrol content [21]. This workfeatures the effect of different spray-drying parameters,e.g. temperature, flow rate, flow rate, and carrierconcentration, on food powders.STUDY OBJECTS AND METHODSThe study was carried out at UCSI University inMalaysia’s Faculty of Applied Sciences, Departmentof Food Science and Nutrition. It featured scientificand methodological literature, publications in scientificjournals, conference papers, patents, regulatorypapers, and Internet resources. The data were grouped,categorized, compared, and consolidated. Because1995 was the year that the topic of spray-drying wasfirst highlighted, the review includes high-quality peerreviewedEnglish-language papers published between1995 and 2021. Most publications were Scopus indexed.The conference papers were chosen based on theircitation quantity and keywords. The review did notinclude books and non-academic resources.RESULTS AND DISCUSSIONBasic principles of spray-drying. Spray-dryinginvolves five major stages [22, 23]:1) Concentration. The feed is concentrated beforebeing pumped into the spray-dryer;2) Atomization. The fluid products are dispersed intofine droplets and pumped into the drying chamber via anatomizer;3) Droplet-air contact. The atomized feed comes incontact with the hot gas. Water evaporates, leaving adry product. The contact time between spray-dropletsand the hot air is very short, which provides an efficientdrying process of heat sensitive materials withoutthermal decomposition;4) Droplet drying. It occurs in two sub-stages. Thefirst sub-stage happens at a relatively constant rate.During this sub-stage, the surface of the droplets isquickly moisturized by the water trapped inside thedroplets. The second sub-stage happens when thesurface of the droplets runs out of moisture. This substageyields a dried product;5) Separation. The dried powder passes through thecyclone and is then collected in the collection vessel.The air is exhausted from the top of the cyclone andpasses through the bag filter.Main properties of spray-dried powders. Primarypowder properties include hygroscopicity, moisturecontent, solubility, particle density, particle sizedistribution, appearance, color bulk density, particlemorphology, and surface composition [24]. In additionto moisture content, some important characteristics ofspray-dried powders also include particle porosity, size,and rehydration [20]. As a result, scientific publicationsconcentrate mostly on the effect of feed qualities anddrying conditions on the physical properties of powder,237Pui L.P. et al. Foods and Raw Materials. 2022;10(2):235–251although the results are sometimes confusing [25]. Thespray-dried powders are analyzed in a few common tests( Table 1).The powder yield depends on the kind of fruitand the carrier agent. For example, orange juicepowder has a big range of yield, from 25 to85% [49]. However, acai juice powder yield wasreported as 48.49% [26]. The moisture content isone of the main characteristics of powder whichaffects mainly solubility and bulk density [24].Moisture content of spray-dried tomato powder wasreported as 3.11–9.30%, whereas watermelon juicepowder obtained by the same method had 1.47–2.48%moisture content [50, 51].Fruit juice powder has a high hygroscopic feed andthermoplastic nature. As a result, it sticks to the dryerwalls, which is one of the major problems in spraydrying[52]. The other reason might be its low meltingpoint temperature, high water solubility, and low glasstransition temperature [53]. Stickiness normally occursif particles are not dry enough when they come incontact with one another or with the drying wall andthus stick to the drying chamber [19]. Stickiness causesoperational issues and lowers the yield [16, 14].Reported hygroscopicity of 12.48–15.79 for acaipowder, while Rodrigues-Hernandez et al. stated36.32–48.93 for cactus pear juice powder [26, 54].According to Fitzpatrick et al., particle size and particledistribution eventually have significant impact on thepowder flowability, handling, and processing [43, 55].Solubility is another important property of powders[49, 50]. It can be affected by compressed airflow rates, carrier agents, and low feed rates [24]. Thewater solubility index increased when maltodextrinreached 96% [56]. According to Mahendran, 30%of maltodextrin produced a guava powder with 95%solubility, whereas 60% of maltodextrin added to guavajuice decreased the solubility to 86% [38]. Bulk densityis an important powder property as it determines thesize of containers, which eventually affect the handlingand transportation costs.Consumers prefer it when the powder is reconstitutedwell and can be instantly dissolved in water [20, 57].Mango powder showed a good reconstitution property:it completely dissolved in warm water at 40°C with nosuspended particles in the solution [52]. Reconstitutedpineapple powder was found to have a lower lightnessbut a higher redness and yellowness, probably, as aresult of the non-enzymatic browning reaction thatoccurred during spray-drying [58].Youssefi et al. measured the color change in thepear cactus juice powder and its reconstituted solution.The slight changes in the color (ΔE) ranged from 6.7 to9.8 [17]. L* was affected neither by the dryingconditions nor by the color change, only by themaltodextrin concentration. The L* values of thereconstituted samples (13.00–16.00) were similar tothose of the untreated juice (13.02), which meant that thespray-drying process did not darken the finished product.Factors affecting the properties of spray-driedpowder. Table 2 shows the production of differentfruit powders obtained by spray-drying. Spray-dryingparameters are important and must be controlled asthey affect the quality and quantity of powder. Someparameters of spray-drying include inlet and outlettemperature, air flow rate, feed flow rate, atomizer,carrier agents, and concentration. Different parametersaffect such powder properties as bulk density, solubility,hygroscopicity, particle size, flowability, and glasstransition temperature [50].Inlet air temperature and outlet temperature.Table 2 demonstrates the effects of inlet air temperatureon the physicochemical properties of spray-driedfruit powders. Such powder properties as moisturecontent, bulk density, particle size, hygroscopicity, andmorphology are all affected by the initial settings ofinlet air temperature [61]. Inlet air temperature proveda more important factor than maltodextrin content,judging by bulk density, caking, and water solubilityindex [62].Inlet air temperature can range from as low as80°C for red beet to as high as 205°C in for pear cactus[54, 63]. However, the normal range for spray-dryingis 110–160°C [50, 64]. Nevertheless, Phisut reported thatthe inlet air temperature of 150–220°C is commonlyused for food spray-drying [61]. Some recent studiesof spray-drying of guava, pineapple, and bael powderrevealed the inlet air temperature of 148, 160, and 166°C,respectively [65–67].Quek et al. found that the moisture content ofspray-dried powder decreased as inlet air temperatureand outlet temperature grew higher [51]. The outlettemperature should be the same to maintain theproduct quality. For every 2–3°C increase in the inletair temperature, the outlet air temperature is usuallyincreased by 1°C. According to [49, 51, 68], a higherinlet air temperature reduced the residual moisturecontent. When the inlet air temperature was increased,the moisture content fell down because the heat transferhappened at a faster rate between the product and thedrying air [61].The inlet air temperature can also affect thehygroscopicity of powder [61]. Similarly, powdersproduced at higher inlet air temperatures were morehygroscopic [24, 26]. Higher inlet air temperatureslowered the moisture content in the powder, causing thepowder to absorb moisture from the environment [61].Inlet air temperature can also affect bulk density. Inparticular, increasing the inlet air temperature causedthe bulk density to drop [49]. For instance, the bulkdensity of acai juice powder decreased as the inlet airtemperature increased [26].When temperature increased during spray-drying,case-hardening appeared at the outer layer of atomizedpowder [61]. Particle size was reported to increasetogether with temperature. Higher drying temperaturesresulted in faster drying rates, triggering an earlystructural formation and preventing the particles238Pui L.P. et al. Foods and Raw Materials. 2022;10(2):235–251Table 1 Spray-dryer conditions in fruit powder productionPowder InitialsampleTotalsolidsInlettemperature,°COutlettemperature,°CAspirator rate/airvelocityFeed rate Atomizationrate/compressorpressureAnalysis ReferencesAcai Pulp – 138–202 82–114 73 m3/h, 0.06 MPa 5–25 g/min – Process yield,moisture content,hygroscopicity,anthocyaninretention, outlettemperature[26]Amla Juice – 120–200 81–119 75 m3/h 13–15 mL/min 0.12 mPa Moisture content,hygroscopicity,bulk density,water solubilityindex, surfacemorphology,DPPH, totalphenolic content[27]AndesberryJuice 9°B 12 70 10 m3/h 485 mL/h 4 bar Particlemorphology,size, thermalanalysis, volatilecompounds,anthocyaninactivity[28]BayberryJuice 11°B 150 80 100% (35 m3/h) – 439 L/h Product recovery,moisture content,water activity,glass transitiontemperature,surfacecomposition[29]Ber Juice – 170–210 – 40–80 m3/h 1 L/h9–21%– Color, bulk density,hygroscopicity,packed density,outlet temperature[30]BlackcurrantExtract Final35°B150, 160,180, 20570, 70,85, 100– – – Total polyphenol,antioxidantactivity[31]BlackmulberryJuice – 110–150 – 800 L/h 150 mL/h 4.65 bar Yield, moisturecontent, bulkdensity, solubility,surfacemorphology,glass transitiontemperature,particle size[32]BlackberryPulp – 140–180 99–115 35 m3/h 0.49 kg/h 0.36 m3 airflowMoisture content,hygroscopicity,anthocyanincontent,color, surfacemorphology,particle size[33]BlueberryExtract 30%totalsolids160 70 – – 23 000 rpm Particle size, truedensity, waterbindingcapacity,anthocyanincontent[34]239Pui L.P. et al. Foods and Raw Materials. 2022;10(2):235–251Continuation of Table 1Powder InitialsampleTotalsolidsInlettemperature,°COutlettemperature,°CAspiratorrate/airvelocityFeed rate Atomizationrate/compressorpressureAnalysis ReferencesCantaloupeJuice – 170–190 75–77 – – – Moisture content,water activity,vitamin C,β-carotene content,dissolution, surfacemorphology[35]ElderberryJuice 10–13°B 70–120 – – 180 & 300 mL/hr – Total phenoliccontent, color[36]Gac Aril – 120–200 83–125 56 m3/h 12–14 mL/min 0.06 mPa Moisture content,water activity, bulkdensity, antioxidantactivity, color totalcarotenoid, watersolubility index[37]Guava Concentrate10.5°B 160 80 – – 40 000 rpm Moisture content,pH, titratableacidity, total sugars,vitamin C, totalsoluble solids[38]Slurry – 170–185 80–85 4 kg/m2 18–20 rpm – Moisture content,solubility,dispersibility,vitamin C[39]IndiangooseberryJuice 19% 120/160 80 – 1.2 mL/min 2.4×102 kPa Moisture content,water activity,vitamin C,dissolution[40]Lime Juice 9.5 140–170 – – 1.75 g/min 5 bar Powder recovery,bulk density,surface morphologycolor[41]Orange Juice 56–57% 160 65 – – – Color, moisturecontent, titratableacidity, wateractivity, particlesize, bulk density,glass transitiontemperature[42]Pitaya Juice 50% 145–175 – – 400 L/h 4.5 bar Moisture content,water activity,color, true density,bulk density, tapdensity, Carr Index,Hausner ratio,glass transitiontemperature,particle size,surface morphology,betacyanin content[43]PomegranateJuice 20–44°B 110–140 – 0.53 m3/min 7 mL/min – Moisture content,hygroscopicity,anthocyanincontent, color,solubility, bulkdensity, yield, totalphenolic content,antioxidant activity[44]240Pui L.P. et al. Foods and Raw Materials. 2022;10(2):235–251from shrinking during drying [69]. A higher inlet airtemperature produced powder with larger particles andgreater swelling [70]. A lower inlet air temperatureresulted in shrunk and smaller particles.The moisture content in the powder was reported toimprove solubility: the solubility of spray-dried raisinextracts and tomato concentrates increased togetherwith the moisture content [18, 24, 50, 51]. The solubilityof spray-dried roselle and tomato powder decreased asthe drying temperature fell [24, 71]. A larger spray-dryeraffected the beetroot powder color changes, namelyincreased the a* value and decreased the b* value [72].Quek et al. focused on the color of spray-driedwatermelon powder [51]. When the inlet air temperatureincreased, the b* value increased. However, thea* values increased at 145–165°C and started to decreaseat 175°C. The lightness of the powders decreased whenthe temperature grew higher. At a higher inlet airContinuation of Table 1Powder InitialsampleTotalsolidsInlettemperature,°COutlettemperature,°CAspiratorrate/airvelocityFeed rate Atomizationrate/compressorpressureAnalysis ReferencesRed beet Concentrate20%totalsolids150, 165,180, 195,21087–115 56 m3/h 390–560 g/h – Moisturecontent,hygroscopicity,drying ratio,drying rate,productivity,bulk density,color, Tg,betayanincontent[45]RedpitayapeelPuree – 155–175 75–85 900 m3/min – 15 000 rpm Color,hygroscopicity,moisturecontent,solubility,water activity,betacyaninretention[46]SaturejaMontanaL.Extract – 135–140 60–70 – – 20 000–21 000 rpm Yield, moisturecontent,bulk density,hygroscopicity,water solubilityindex, totalphenoliccontent, totalflavonoid,sensoryevaluation[47]SeabuckthornJuice – 148.79–191.2165–9 2.1 kg/cm3 30 rpm 50 Hg Moisturecontent,dispersibility,vitamin C,overall colorchange[48]The table is based on the findings of this studytemperature, the color of the powders turned darker. Redcolor decreased when the inlet air temperature rose [51].The stability of heat sensitive pigment depended onthe inlet air temperature. The lycopene content inwatermelon juice powder decreased at a higher inletair temperature, which was in agreement with anotherpublication on tomato pulp [50]. The reduction oflycopene content was likely due to thermal degradationand oxidation. On the other hand, Tonon et al. alsoreported that the inlet air temperature affected theanthocyanin content in acai juice powder [68]. A higherinlet air temperature also decreased the amount ofpigments in powder [61].Atomization rate and air flow rate. Tables 3 and 4illustrate the effects of atomization rate and air flowrate, respectively. As for atomization rate, spray-dryinguses different ranges of speed. Atomization rate hada positive effect on sirih powder yield [73]. Amla and241Pui L.P. et al. Foods and Raw Materials. 2022;10(2):235–251Table 2 Effects of inlet air temperature on physicochemical properties of spray-dried fruit powdersPowder Inlet airtemperature,°CYield/recovery,%MoisturecontentWateractivityHygroscopicityDensityPorosityParticlesizeCaking SolubilityColor PigmentAntioxidantactivityVitaminCReferencesAcai 138–202 +ve –ve – +ve – – +ve – – – –ve – – [26]Acerolapomace170–200 – –ve – –ve – – – –ve +ve – – – – [59]Amla 100–200 – –ve – –ve –ve – – – NS L*+ve – –ve – [27]Ber 170–210 – – – +ve –ve – – – – – – – – [30]Blackmulberry110–150 +ve –ve – – –ve – – – +ve – – – – [32]Blackberry140–180 – –ve – –ve – – NS – – L*+ve –ve – – [33]Cantaloupe170–190 – –ve – – – – – – – L*–vea*+veb* NS– – – [35]Gac 120–200 – –ve –ve – –ve – – – – L* NSTCNS–ve –ve – [37]Guava 170–185 – –ve – – – – – – +ve – – – +ve [39]Jujube 140–160 – NS – +ve – – – – – L*–veTC +ve– – +ve [60]Lime 140–170 +ve NS – +ve – – – – – – – – – [41]Orangejuice110–170 – –ve – NS – NS – – – – – – – [49]Pitaya 145–175 – –ve – – – – – – – LNS NS – – [43]Pomegranate110–150 NS –ve – NS +ve – – – +ve TC+vea*–ve–ve +ve – [44]Redpittayapeel155–175 – –ve –ve –ve – – – – +ve L* +vea*–ve–ve – – [46]Watermelon145–175 – –ve NS – –ve – –ve CI NSHR NS+ve L*–vea* NSb*+ve–ve – – [51]+ve – positive effect; –ve – negative effect; NS – no significant effect; – – not reportedorange powder with greater moisture content resultedfrom an increase in atomization rate [27, 49]. However,Tee et al. stated that raising the atomization rate by80–100% produced sirih powder with low moisturecontent and low hygroscopicity [73].As for the air flow rate, Fazeli et al. and Goula andAdamopoulos applied air flow rate of 400–800 and500–800 L/h, respectively, to produce black mulberryand tomato powders [32, 74]. Fazeli et al. reported thatthe powder yield increased with faster air flow rate,producing a powder of lower moisture content andhigher solubility [32]. Greater air flow rates reducedthe moisture content and increased the density [32, 74].However, as the air flow rate increased, the solubilityof black mulberry fell down while that of tomatoincreased [32, 74].Feed solid content and flow rate. Table 5summarizes the effects of feed flow rate on thephysicochemical properties of spray-dried powderedfruits. Most of the initial sample used for spray-dryingwere in the form of juice [36, 51, 76]. Two types of valuewere reported for Brix sample solids. Moßhammer et al.,used pear cactus juice with 65% of total solids whileRoustapour et al. reported lime juice with 12% totalsolids as spray-drying feed [75, 76]. The Brix valuealso depended on the fruit. For instance, bayberry juicespray-dried into powder had Brix of 7–17°, whereas forpomegranate juice it was 20–44° [65].Different rates of spray-drying feed have alsobecome subjects of scientific research. Elderberryjuice was spray-dried into powder at the feed rate of180 and 300 mL/h [36]. However, Ferrari et al. spraydriedblackberry pulp at the feed rate of 0.49 kg/h [33].Bazaria and Kumar utilized feed flow rate of400 mL/h to obtain high-quality spray-dried powderedbeetroot [78]. Ribeiro et al. used different levels ofintake temperature (110, 140, and 170°C), feed flow (0.36,0.60, and 0.84 L/h), maltodextrin quantity (14–26%),242Pui L.P. et al. Foods and Raw Materials. 2022;10(2):235–251improve the recovery by decreasing the stickinesswhich causes the product to stick together or to thedrying chamber [16]. An ideal spray-drying carrier hasa high solubility, bland taste, and good emulsifying anddrying properties. Its limited solution viscosity is at35–45% solids content; it is nonhygroscopic, nonreactive,and cheap [83]. Maltodextrin, alginate, Arabic gum,modified starch, inulin, and their combinations served ascarriers for spray-drying of carotenoid-rich goldenberry(Physalis peruviana L.) juice, while cellobiose was usedas control [84].Table 6 demonstrates different carrier agents in fruitpowder production, the most common carrier agentsbeing maltodextrin and Arabic gum. Arabic gum hada high glass transition temperature and proved efficientin flavor retention [85]. Arabic gum is expensivebecause its supply from Middle East and Africa is asunpredictable as its quality. Maltodextrin is not onlyneutral in color and taste but also relatively cheap, whichmakes is the most common carriern commercial spraydrying[7, 16]. Maltodextrin consists of β-D-glucoseunits that are linked by glycosidic bonds (1→4), withdextrose equivalency (DE) that indicates its reducingand maltodextrin dextrose equivalent (DE) asindependent variables (5, 10 and 15 DE) [79].Tonon et al. observed that high feed flow ratesresulted in a lower yield [26]. This correlation wasrelated to the slow heat and mass transfer. Higher feedflow rates triggered wall deposit, which reduced theyield [80]. Feed flow rate also had an adverse effect onthe powder moisture content [77]. High feed flow rateshortened the time of contact between the feed and thedrying air, thus decreasing the effectiveness of the heattransfer. An increment in feed flow rate also affectedthe evaporating intensity, which lowered the inlet airtemperature and increased the water content in thepowder [81]. Chen et al. reported that higher feed flowrate resulted in low-hygroscopicity jujube powder [60].In addition, higher feed flow rates increased the particlesize [80]. Higher feed flow rates increased the solubilityof fermented carrot-and -watermelon juice powder [82].Type and concentration of carrier agents. Selectingthe best drying aids is one of the most important stepsin spray-drying of fruits and vegetables. Drying aids, orwall materials, or carriers, are mostly used to increasethe glass transition temperature of the feed. They canTable 3 Effects of atomization rate on physicochemical properties of spray-dried powdersPowder Atomization rate Yield/recovery, % Moisture content Hygroscopicity Density ParticlesizeSolubility ReferencesAmla 30–50 – +ve NS NS – NS [27]Sirih 80–100% +ve –ve –ve – –ve – [73]Orange 10 000–25 000 rpm – +ve – NS NS – [49]+ve – positive effect; –ve – negative effect; NS – no significant effect; – – not reportedTable 4 Effects of air flow rate on physicochemical properties of spray-dried powdersPowder Air flow rate Yield/recovery, % Moisture content Density Solubility ReferencesBlack mulberry 400–800 L/h +ve –ve +ve –ve [32]Lime 47.1–57.8 m3/h +ve NS NS – [41]Tomato 500–800 L/h – –ve +ve +ve [74]+ve – positive effect; –ve – negative effect; NS – no significant effect; – – not reportedTable 5 Effects of feed flow rate on physicochemical properties of spray-dried fruit powdersPowder Feed flowrateYield/recovery, %MoisturecontentWateractivityHygroscopicityDensity ParticlesizeSolubilityColor Pigmentcontent/retentionReferencesAcai 5–25 g/min –ve +ve NS – – – – – [26]Jujube 3–5 m3/h – +ve –ve – – – L*–veTC+ve– [60]Orange 150–450 – –ve – NS NS – – – [49]Watermelonandcarrot2–5 mL/min – +ve – – – +ve – –ve [77]+ve – positive effect; –ve – negative effect; NS – no significant effect; – – not reported243Pui L.P. et al. Foods and Raw Materials. 2022;10(2):235–251Table 6 Applications of different carrier agents in spray-drying of fruit powdersPowder InitialsampleCarrier agent Concentrations/percentageAnalyses ReferencesAcai Pulp Matodextrin (DE20) & Arabicgum6% Process yield, moisture content,hygroscopicity, anthocyaninretention, outlet temperature[8]Amla Juice Maltodextrin 3–9% (w/v) juice Moisture content, hygroscopicity,bulk density, water solubilityindex, surface morphology,DPPH, total phenolic content[38]Bayberry Juice Maltodextrin (DE 12 & 19) 1:1 (fruit juice) Moisture content, color [64]Maltodextrin DE 10 10–50% Product recovery, moisturecontent, water activity, glasstransition temperature, surfacecomposition[29]BlackmulberryJuice Maltodextrin DE 6, 9, 20 8–16% Yield, solubility, bulk density,moisture content[32]Blackberry Pulp Maltodextrin (DE 20) 5–25% Moisture content, hygroscopicity,anthocyanin content, color, surfacemorphology, particle size[33]Blackcurrant Extract Maltodextrin (DE 11, 18 and 21) Total °B 35 Total polyphenol and antioxidantactivity[31]Blueberry Extract Maltodextrin (DE 18.5) Total solids 30%(blueberry solids 20%)Particle size, true density, water-binding capacity, anthocyanincontent[34]Cantaloupe Juice Maltodextrin (DE 9–13) 10% Moisture content, water activity,vitamin C, carotene content, dissolution,surface morphology[35]Elderberry Juice Acacia gum &maltodextrin (DE 4–7)5:1–5:4; 1:1 (juice) Total phenolic content, color [36]Gac Fruit aril Maltodextrin DE 12 10–30% Moisture content, water activity,pH, color, water solubilityindex, bulk density, carotenoid,antioxidant[37]Gooseberry Juice Maltodextrin 19% TSS Moisture content, Water activity,vitamin C, dissolution time[40]Guava Juice Maltodextrin 500 RM1249 7–12% Moisture content, solubility, dispersibility,vitamin C[39]Jucara Pulp Arabic gum, Maltodextrin,GelatinArabic gum andMaltodextrin (5–55%),Gelatin (5–15%)Anthocyanin content, moisturecontent, water activity, hygroscopicity,solubility, total colorchange, bulk density[88]Lime Juice Maltodextrin (DE 5) 10–30% Moisture content [76]Mango Juice Maltodextrin, arabic gum,starch wax, crystalline celluloseSurface morphology, stickiness,solubility, powder diffraction[14]Orange ConcentrateMaltodextrin (DE 6-21) – Glass transition temperature,residue formation[74]Juice Maltodextrin and liquid glucose – Particle size, wettability time,insoluble solids, bulk density,moisture content[49]Pineapple Juice Maltodextrin (DE10) 10–12.5% Moisture content, color, bulkdensity, solubility[7]Pitaya Juice Maltodextrin 20 and 30% Moisture content, water activity,color, true density, bulk density,tap density, Carr’s Index, Hausnerratio, glass transition temperature,particle size, surface morphology,betacyanin content[43]244Pui L.P. et al. Foods and Raw Materials. 2022;10(2):235–251reported 22.62% maltodextrin concentration as optimalfor spray-drying of feijoa pulp, while Dantas et al. used23% of malto-dextrin to produce powdered avocadodrink [93, 94]. The flowability, color, antioxidantactivity, and phenol content of barberry powder wereoptimal at 13% (w/w) of maltodextrin [95].Table 7 shows the effects of maltodextrin concentrationon the physicochemical properties of spray-driedpowder. Maltodextrin reduced the moisture content,which might be explained by the increment in feedsolids and the low amount of free water [38, 50, 51, 96].With the use of it, the yield was 18–35% but there wasmore deposit on chamber wall [49]. Maltodextrinincreased the yield up to 18–35% but the depositon the chamber wall reached 65–82% [49]. Yet thecapacity [86]. Lee et al. studied the use of additives ascarriers in spray-drying, as well as the impact on suchphysicochemical parameters as hygroscopicity, flavorretention, and color indexing [87].Maltodextrin has been used to spray-dry stickyproducts, e.g. orange, tamarind, blackcurrant, raspberry,and apricot juice, honey, mango pulp, raisinjuice, lime juice, watermelon pulp, and sweet potatopuree because it facilitates the drying process [25].The percentage of carrier agents incorporated rangesfrom 3% for watermelon juice powder to 40–64% forpomegranate juice powder [44, 51]. The concentration ofmaltodextrin was 15, 20, and 25%, respectively, in theproduction of spray-dried cempedak, papaya, and terungasam powder [90–92]. However, Henao-Ardila et al.Continuation of Table 6Powder InitialsampleCarrier agent Concentrations/percentageAnalyses ReferencesPitaya Juice Maltodextrin DE 10 8–22% w/w Color, hygroscopicity, moisture content,water activity, solubility, betacyanincontent[46]Pomegranate Juice Maltodextrin, arabicgum, starch wax8 and 12% Yield, solubility, color, total anthocyanin,antioxidant[17]SeabuckthornfruitJuice Maltodextrin DE 20 20–49 g in 100 mL Moisture content, solubility, dispersibility,vitamin C, overall color difference[48]Strawberry Juice Maltodextrin 10–30% Vitamin C loss, solubility,anti-caking, sensory[89]Watermelon Juice Maltodextrin (DE 9-12) 3 and 5% Moisture content, water activity,dissolution, color, carotene content, sugar[51]Table 7 Effects of maltodextrin concentration on physicochemical properties of spray-dried powderPowder Maltodextrinconcentrations,%Yield/recovery,%MoisturecontentWateractivityHygroscopicityDensity ParticlesizeCaking SolubilityColor Pigmentcontent/retentionAntioxidantactivityVitaminCReferencesAcai 10–30 – NS – +ve – +ve – – – – – – [26]Amla 3–9 – –ve – –ve NS – – NS L*+ve – –ve – [27]Blackmulberry8–16 +ve –ve – – –ve – – +ve TC– – – – [32]Blackberry5–25 – –ve – –ve – – – –ve – – [33]Guava 5.95–13.03– +ve –ve – – – – +ve – – – –ve [39]Pineapple– – – – –ve BD – – –ve NS – – – [7]Pitaya 20 30 – –ve NS +ve – NS L*+ve –ve – – [43]Pomegranate44.1–59.1 +ve –ve – –ve +ve BD – – +ve TC+vea*RP–ve+ve – – [44]Redpittaya8–22 – +ve +ve +ve – – – +ve L*–vea*–ve–ve – – [46]BD – bulk density; TC – total color changes, +ve – positive effect; –ve – negative effect; NS – no significant effect; – – not reported245Pui L.P. et al. Foods and Raw Materials. 2022;10(2):235–251Table 8 Applications of Response Surface Methodology (RSM) in spray-drying of fruitsPowder StartingmaterialIndependentvariablesResponse variables OptimizationDesign Software ReferencesAcai Juice Inlet air temperature,feedflow rate, maltodextrinconcentrationProcess yield, moisturecontent, hygroscopicity,anthocyanin retention, outlettemperatureRSM Rotatable centralcompositedesignStatistica5.5[26]Acerola Juice Inlet air temperature,Drying aid/acerola,percent replaceof maltodextrin bycrystalline celluloseMoisture content,hygroscopicity,water solublity,flowabilityRSM Centralcompositedesign (CCD)Minitab15[59]BlackberryPulp inlet air temperature,maltodextrinconcentrationMoisture content,anthocyanin retention,hygroscopicity, particle size,color parametersRSM Centralcompositerotatable designStatistica8.0[33]CashewappleJuice Drying aid/juice, percentreplaceof maltodextrin bycrystalline celluloseAscorbic acid retention,hygroscopicity, flowability,water solubilityRSM RSM with 11runsMinitab15[85]Guava Slurry Inlet air temperature,maltodextrinconcentrationsolubility, moisture content,dispersibility, vitamin CRSM CCRD – [39]Jujube Juice Inlet air temperature,maltodextrinconcentration, feed flowrateMoisture content, vitamin C,color, hygroscopicityRSM Box Behnken – [60]Orange Juice Inlet air temperature,atomization rate, flowrateParticle size, wettabilitytime, insoluble solids, bulkdensity, moisture contentFullfactorialdesignCompleterandomdesign– [49]PineappleJuice Atomizationrate, maltodextrinconcentrationApparent and true density,color, moisture content,solubilityCompletefactorialdesign3 repetition atcenter point– [7]PomegranateJuice Inlet air temperature,maltodextrinconcentration, feed/ mixconcentrationMoisture content,hygroscopicity, anthocyanincontent, color, solubility,bulk density, yield,total phenolic content,antioxidant activityRSM CCD Designexpert6.0[44]RedpitayapeelPuree Inlet air temperature,outlet temperature,maltodextrinconcentrationColor, hygroscopicity,moisture content, wateractivity, solubility,betacyanin contentRSM CCD – [46]concentration of maltodextrin is important in controllingthe quality of the powder. For instance, a higher amountof maltodextrin dextrose equivalent made it possibleto obtain low-hygroscopicity liquorice [97]. Leyva-Porras et al. investigated the effect of spray-dryingsettings on the microencapsulation of bioactivecomponents and the physicochemical qualities ofstrawberry juice with maltodextrin as a transportingagent [98].Reduction in maltodextrin generally improved thesolubility [7]. Similar observation was reported byMoreirra et al., who used a drying assistance ratio ofcashew apple juice dry weight (5:1) and cashew treegum substituting maltodextrin in 50% of spray-dryingof cashew apple juice generated with high solubility(> 90%) [59]. The solubility of spray-dried mangopowder decreased as the cellulose concentration grew.At 9% of cellulose, the solubility values of mangopowder were 72, 71, and 31% using maltodextrin, arabicgum, and waxy starch, respectively [14]. Quek et al.studied watermelon powder production and discoveredthat adding maltodextrin in greater quantities than 10%246Pui L.P. et al. Foods and Raw Materials. 2022;10(2):235–251drying parameter on powder properties. Theseparameters included inlet air temperature, atomizationrate, air flow rate, and feed flow rate. The article alsosummarized the effects of different carrier agentson the powder. Inlet temperature of spray-dryer andcarrier concentration were found to increase theproduct yield and solubility, as well as to decrease themoisture content, pigment, and antioxidant content.However, inlet temperature proved to be the mainfactor that affected the powder density. On the otherhand, atomization rate had little effect on powderproperties. Certain powder properties depended onthe type of fruit and the range of parameters applied.The review showed that the impact of additives andencapsulation on the physicochemical parameters offruit extract powder is critical. Changing the spraydryersettings can solve the technical obstacles inspray-drying of fruit extracts. In addition, spray dryingis a newer and cheaper method of turning fruit extractsinto powder.CONTRIBUTIONLiew Phing Pui gathered data, donated dataand analysis tools, conducted the study, wrote themanuscript, and submitted it. Abdul Kalam SaleenaLejaniya was in charge of data collection and datacontribution, formatted the manuscript and proofreadthe article.CONFLICT OF INTERESTThe authors note that they have no known conflictingfinancial or personal interests that might have impactedthe findings of this study.led to color loss [51]. These results confirmed thoseobtained by Farimin and Nordin, who studied roselleand-pineapple powder [96]. Papadakis et al. reportedthat the exact color of each powder depended on theratio of raisin juice solids:maltodextrin solids [18].Optimization of spray-drying process. Responsesurface methodology is applied to determine theoptimum condition of spray-drying because thisprocedure is comprehensive, simple, and highly efficient[82, 99]. The central composite design builds aquadratic model for the response variable without acomplete three level factorial experiment. Only byoptimizing the spray-drying process, food producers canobtain better powder properties and yield [26].Table 8 summarizes the use of response surfacemethodology as optimization for spray-drying offruit powder. The main independent variables areinlet air temperature, maltodextrin concentration,and feed or flow rate [20, 26, 100]. Moisture contentand water solubility are the most importantproperties of food powder [19]. However, yield andhygroscopicity proved to be the common responsevariables [26, 59]. Consequently, optimization of theamount of carrier is an important step in making acommercial product [16]. Li et al. applied the Box-Behken method to obtain the optimal conditionof 142.8°C, 23.7% core material, and 11.7% feedsolid in spray-drying of plum [101]. Pandey et al.reported the inlet temperature of 166.64°C and 9.26%maltodextrin concentration as optimal conditions forfruit slurry spray-drying process [102].CONCLUSIONThis review covered the basic principles of spraydryingwhile determining the effects of each spray-