Glass Transition Behavior of Spray Dried Orange Juice Powder Measured by Differential Scanning Calorimetry (DSC) and Thermal Mechanical Compression Test (TMCT)

Spray drying behavior of orange juice concentrate with various levels of maltodextrin (DE 6) was studied. Five combinations of orange juice concentrate and maltodextrin (25:75, 30:70, 35:65, 40:60, and 50:50) were spray dried at 160 and 65°C inlet and outlet temperatures, respectively. The product recovered with 50% maltodextrin concentration was sticky and only 20% powder was recovered. The recovery of orange juice powder increased as the amount of maltodextrin in powders increased. The particle size and bulk density remained almost the same in all except in 50% maltodextrin powder which was slightly larger and more dense. The moisture content of spray dried powders was high and desiccated before measuring glass transition temperature. The anhydrous spray dried powders showed increased T_g values with increasing maltodextrin concentration, from 66°C in 50% maltodextrin to 97°C in 75% maltodextrin containing powders. The glass rubber transition (T_g-r) values of all the products measured using novel Thermal Mechanical Compression Test (TMCT) were higher than T_g values measured by DSC; the difference in values increased with increase in maltodextrin concentration.     

改善营养糊冲调性和流动性的配方优化和工艺研究

以黑米、黑大豆、黑芝麻、大米、植脂末、麦芽糊精、蔗糖为原料研制速溶即食营养糊.黑米、黑大豆和大米经过挤压膨化,将制得的膨化粉与黑芝麻、植脂末、麦芽糊精、蔗糖按不同比例调配,研究其添加量对粉体性质、冲调性和流动性的影响.结果表明:原料添加量为黑米5％,黑大豆2.5％,黑芝麻5％,大米42.5％,植脂末5％,麦芽糊精17.5％,蔗糖22.5％时,所得营养糊颜色、风味、口感、冲调性及流动性为最佳.     

CFD Modeling and Simulation of Maltodextrin Solutions Spray Drying to Control Stickiness

Particle stickiness during spray drying can lead to operational problems or be used to perform agglomeration inside the chamber. A simplified computational fluid dynamics approach is proposed to simulate the spray drying of 40% w/w aqueous solutions of maltodextrin DE12 and DE21 in a pilot cocurrent spray dryer equipped with rotary atomizer. Drying was simulated at steady state considering the geometry of the equipment (drying chamber, air inlet, atomizer) and the close relation between drying air and product properties. To take into account the lower drying rate of liquid solutions compared to pure water, the water vapor pressure of the drying particles was decreased with a coefficient determined from experimental data on air temperatures and humidities measured in the chamber. The evolution of particle temperature and water content was simulated. From these values and glass transition temperatures of the considered materials, it was possible to determine zones and operating conditions for which particles could be sticky inside the chamber. Maltodextrin DE12 was quickly dried close to the atomizer reaching a stable nonsticky state below glass transition temperatures Tg, while maltodextrin DE21 with lower Tg could exhibit a sticky behavior in a wider part of the chamber, depending on the liquid flow rate. This approach provides a methodology to evaluate possible stickiness to avoid fouling of the plant or to optimize powder insertion position for agglomeration.     

Moisture sorption characteristics and glass transition temperature of apple puree powder

The aim of this study was to characterise the influence of different foam‐mat‐drying methods on the moisture sorption characteristics and glass transition temperatures of apple puree powder. Apple puree was foamed with the addition of 2.5% egg albumin and 0.5% methylcellulose. Convective air‐drying and microwave‐drying techniques were used. Also foamed puree with and without maltodextrin (6% or 15% w/w) was freeze‐dried. Moisture equilibrium data of powders were determined by using a static desiccator method in a water activity range of 0.0–0.903. Modulated differential scanning calorimetry (MDSC) was used to obtain the glass transition temperature. No effect of drying method on sorption properties and glass transition temperatures of apple puree powders was observed. The addition of maltodextrin to the apple puree caused an increase in T_g by 10–30 °C depending on the amount of incorporated additive. Addition of maltodextrin significantly reduced the hygroscopicity of apple puree powders.     

Spray-Drying of Amylase Hydrolyzed Sweetpotato Puree and Physicochemical Properties of Powder

ABSTRACT:  Spray-drying, which has been used for commercial production of functional ingredients from several fruits and vegetables, has not yet been studied for sweetpotato processing. Thus, the objective was to determine the effects of viscosity reduction of sweetpotato puree with alpha-amylase, maltodextrin (MD) addition, and inlet air temperature on the physicochemical characteristics of spray-dried sweetpotato powder. A face-centered cube design was used to evaluate the effects of amylase level (0, 3.75, and 7.5 mL/kg puree), MD concentration (0%, 10%, and 20%), and inlet air temperature (150 °C, 190 °C, and 220 °C) on powder characteristics. Model-fitting using response surface methodology was performed to examine the effects of independent variables on the moisture content, color, water absorption, solubility, particle size, bulk density, and glass transition temperature. The data were fit to a full second order polynomial equation. However, only the linear and quadratic terms proved to be significant for most dried powder attributes. MD significantly increased powder solubility, altered the hue value, and raised the glass transition temperature of the powder. Pretreatment with alpha-amylase resulted in a lower glass transition temperature and a decrease in particle size. Overall, results show that good quality sweetpotato powders can be produced using this drying method, with potential applications in food and nutraceutical products.     

Degradation Kinetics and Storage Stability of Vacuum Spray-Dried Micro Wet-Milled Orange Juice (<Emphasis Type="Italic">Citrus unshiu</Emphasis>) Powder

The aim of this work was to evaluate the degradation kinetics and stability of micro wet milled orange juice powders obtained by vacuum spray drying, using maltodextrin as a carrier agent. Powders were produced with four combinations of orange juice solids/maltodextrin solids 60:40, 50:50, 40:60, and 30:70 by weight. Ascorbic acid degradation, color, and antioxidant activity of powders were evaluated throughout 90 days. Powders were stored at 10, 25, and 35 °C and relative humidity of 33%. Temperature and storage time negatively influenced the stability of ascorbic acid and color, whereas antioxidant activity increased at the beginning of storage at a higher temperature then decreased slightly after 60 days. For stability study, powders were stored at different water activities (0.11 to 0.84) in order to determine the plasticizing effects of water on glass transition temperature. Both water activity and glass transition temperature were used to predict the critical conditions for storage. Vacuum spray dried powder produced with a ratio of 30:70 (orange juice solids/maltodextrin solids) was considered as the most stable, since it showed highest critical water activity (a_w?=?0.61) and lowest moisture content (0.11 g water/g of dry solid) among the four powders. Vacuum spray drying using superheated steam as the heating medium was proven to be an effective way of producing orange juice powders with minimum loss of nutrients.     

Effect of apparent viscosity on fluidized bed drying process parameters of guava pulp

Pressure drop and minimum fluidization velocity were experimentally studied in a vibro-fluidized bed of inert particles subjected to different vibration intensities during drying of guava pulp. Maltodextrin was added to the pulp in order to prevent stickiness between particles and the consequent bed collapse. Pulps were initially concentrated, resulting in pastes with different soluble solids content, and a constant fraction of maltodextrin was guaranteed in the final pulp samples. The pulp rheological behavior as affected by temperature and total soluble solids content, including maltodextrin, was evaluated and the effect of pulp apparent viscosity on pressure drop and minimum vibro-fluidization velocity were investigated. Two types of inert particles – 3.6 mm glass beads and 3 mm Teflon cylinders – were tested and, due to lower pressure drop presented by Teflon cylinders during operation of the dry vibro-fluidized bed, these particles were adopted for pulp drying process. Increasing pulp apparent viscosity caused a considerable increase in the vibro-fluidized bed pressure drop during pulp drying and, as a consequence resulted in a larger value of minimum vibro-fluidization velocity. On the other hand, the negative effect of increasing apparent viscosity could be attenuated by increasing the fluidized bed vibration intensity, which could prevent stickiness between particles.     

Optimization of bayberry juice spray drying process using response surface methodology

In this study, thirteen different runs according to the central composite design-response surface methodology were used to optimize the quality parameters of spray-dried bayberry juice powder. The independent variables were different levels of inlet air temperature (145.8–174.1 °C) and maltodextrin concentration (22.9–37.0%). The responses were process yield, moisture content, hygroscopicity, glass transition temperature (Tg), total color difference (ΔE), redness, retention of phenolics and anthocyanins, and antioxidant capacity. The optimum operation conditions for the highest Tg, redness, anthocyanins retention and antioxidant capacity with the lowest ΔE and hygroscopicity were obtained at inlet drying temperature of 150 °C and maltodextrin concentration of 31%. This study revealed that by applying these optimal conditions, bayberry juice powder with a 74.16% yield, 3.15% moisture content, 10.25% hygroscopicity, 41.15 °C Tg, 24.74 ΔE, 27.45 Hunter a redness, 89.55% anthocyanins retention, 77.71% phenolics retention, and 30.19 mmol Trolox equivalents/g antioxidant capacity was produced.     

Water sorption and glass transition temperature of spray dried açai (Euterpe oleracea Mart.) juice

Sorption isotherms and glass transition temperature (T_g) of powdered açai juice were evaluated in this work. Powders were produced by spray drying using different materials as carrier agents: maltodextrin 10DE, maltodextrin 20DE, gum Arabic and tapioca starch. The sorption isotherms were determined by the gravimetric method, while the T_g of powders conditioned at various water activities were determined by differential scanning calorimetry. As results, experimental data of water adsorption were well fitted to both BET and GAB models. Powders produced with maltodextrin 20DE and gum Arabic showed the highest water adsorption, followed by those produced with maltodextrin 10DE and with tapioca starch, respectively. With respect to the glass transition temperature, Gordon–Taylor model was able to predict the strong plasticizing effect of water on this property. Both a_w and T_g were used to determine the critical conditions for food storage, at which powders are not susceptible to deteriorative changes such as collapse, stickiness and caking.     

Stickiness curves of high fat dairy powders using the particle gun

High fat (>42%) dairy powders are inherently sticky due to their high levels of liquid surface fat. Incorrect operating conditions when spray drying these powders can rapidly lead to blockages. The particle gun was used to characterise the stickiness curves of high fat cream and cheese powders. Stickiness was shown to increase with increasing temperature to a maximum at 50 °C after which it decreased until no stickiness was observed above 68 °C. A dramatic increase in stickiness for the powders was found when the relative humidity of the air was increased past a certain critical point for each temperature. This was attributed to the lactose component of the powder exceeding its glass transition temperature by a critical amount. Best estimates of the (T−T_g)_crit. values for White Cheese Powder, Low Fat Cream Powder and High Fat Cream Powder were 28, 37 and 38 °C, respectively.     

Influence of the Material and the Surface Roughness of the Drying Support on the Self‐detachment of Maltodextrin Films

The influence of four different materials (glass, stainless steel, polytetrafluoroethylene – PTFE and polyamide) used as a paste drying support on the detachment conditions of dried maltodextrin films was investigated. The tests were accomplished in a drying chamber that allows the spreading of a uniform film of pastelike material over solid plates and the visual observation of the instant of the detachment from the surface. The chamber temperature and the water content of the dried film were compared with the corresponding glass transition temperature curve. The effect of the material roughness on the detachment of the dried maltodextrin film was evaluated comparing glass plates with two different surfaces (smooth and sand‐blasted glass). Results indicate that the higher the surface roughness, the drier should the film be, in order to promote self‐detachment at the same temperature conditions. The chemical and physical interactions between the support material and the dried film also influence the process. The PTFE support required less severe detachment conditions than solids with lower surface roughness.     

Effects of spray drying conditions on the physicochemical and antioxidant properties of the Gac (Momordica cochinchinensis) fruit aril powder

Gac fruit aril has an attractive orange red colour and very high level of carotenoids, giving it exceptional antioxidant properties. However, spray drying of this material has not been successful and malto dextrin is considered as a suitable drying aid to preserve its colour and antioxidant properties. This paper reports the effects of inlet drying air temperature (120, 140, 160, 180 and 200 °C) and maltodextrin addition (10%, 20% and 30%) on the physicochemical and antioxidant properties of the Gac aril powder. Moisture content and bulk density, colour characteristics, total carotenoid content (TCC), encapsulation efficiency and total antioxidant activity (TAA) were significantly affected by maltodextrin concentration and the inlet air temperatures. However, pH, a_w and water solubility index were not significantly influenced by the spray drying conditions. Overall, a good quality Gac powder in terms of colour, TCC and TAA can be produced by spray-drying at inlet temperature of 120 °C and adding maltodextrin concentration at 10% w/v.     

添加麦芽糊精与限制性淀粉酶解对喷雾干燥小米速溶粉的影响

采用喷雾干燥法以两种葡萄糖当量(DE值)的麦芽糊精(MD)为助干剂和限制性淀粉酶解法,考察了处理方法对小米速溶粉的璃化转变温度、集粉率、水分含量、水分活度、堆积密度、结块性和颗粒微观形态的影响。结果表明,较低的DE值、较高的MD使用量和较低的淀粉酶解度可以提高喷雾干燥的集粉率,提高小米速溶粉的玻璃化转变温度和堆积密度,降低小米速溶粉的水分含量和水分活度,同时使其结块性下降;以DE8的MD为助干剂的喷雾干燥效果优于以DE20的MD为助干剂的喷雾干燥效果;相同DE值条件下,限制性淀粉酶解法获得的产品性质均优于添加MD助干剂法,但会引起集粉率的降低。不同的处理对颗粒的微观形态也有显著的影响。      

Effect of the carriers on the microstructure of mango powder obtained by spray drying and its functional characterization

This work aimed the induction of crystallization on powder mango juice during the process of spray drying and the correlation of the microstructure of the powder obtained with the functional properties of stickiness and solubility. To perform this work, we used mango juice with 12 °Brix. Before being dehydrated, the juice undertook addition from the following carriers: maltodextrin, gum arabic and starch waxy in the concentration of 12%. The solution also received addition of crystalline cellulose in the concentrations of 0, 3, 6 and 9%. The powder was obtained through the use of a mini-spray dryer of laboratorial scale. Analyses of microstructure, stickiness, hygroscopicity and solubility were performed on the obtained powder. The microstructure analyses showed that the powders of the mango juices obtained through spray drying using the carriers maltodextrin, gum arabic, starch waxy without the addition of cellulose presented surfaces of amorphous particles. The analysis XRD showed that when 3, 6 and 9% of cellulose were added, the particles showed half-crystalline surfaces. The value of stickiness decreased in terms of the concentration of cellulose reaching values of 0.15, 0.22 and 0.11 Kg-f for maltodextrin, gum arabic and starch waxy, respectively. The functional property of solubility is affected when 9% of cellulose is added reaching the values of 72, 71 and 31% for the carriers maltodextrin, gum arabic and starch wax, respectively.     

Characterization of spray-dried soy sauce powders using maltodextrins as carrier

Soy sauce powders were made by spray drying liquid soy sauce using maltodextrin as the drying aid. Three types of maltodextrin, i.e. DE 5, DE 10 and DE 15, were studied and compared. Each type was incorporated into soy sauce with concentration levels of 20% and 40% (w/v), respectively, as a carrier. The spray-dried soy sauce powders were mixtures of amorphous substances and crystalline salts. Caking related properties including particle size distribution, hygroscopicity, glass transition temperature, flowability and caking strength of the powders were characterized. Soy sauce powders produced from the feed solution of maltodextrin concentration of 40% had a larger particle size dispersion, reduced hygroscopicity, higher glass transition temperatures and smaller cohesive index than their 20% concentration counterparts. Maltodextrin of a smaller DE value produced soy sauce powders with less cohesion, higher glass transition temperature and reduced hygroscopicity. Maltodextrin concentration and DE value greatly influenced the caking strength of the soy sauce powders, with different mechanisms and effects under different storage conditions.     

Textural and Melting Properties of Processed Cheese Spread as Affected by Incorporation of Different Inulin Levels

Inulin as a soluble dietary fiber can be incorporated in processed cheese spread to enhance its functionality. But due to high hygroscope nature of inulin its addition changes the properties of the product. In the present study, effect of textural and melting properties of the processed cheese spread have been studied at different levels (0, 4, 6 and 8 %) of inulin addition. Results showed that as the levels of inulin addition were increased from 0 to 8 %, the firmness and work of shear of cheese spread increased, whereas the stickiness and work of adhesion decreased. On melting properties at 6 % inulin addition the Rapid Visco Analyzer ? cheese melt viscosity index increased significantly (p?<?0.05) as compared to the control; however, further increase of inulin addition did not change it significantly (p?>?0.05).     

New methods to assess water diffusion in amorphous matrices during storage and drying

Water diffusion coefficient is an important parameter for food processing and stability, strongly influenced by the composition and the physical state of the matrix (amorphous glassy or rubbery/crystalline). In this study, two different methods to assess water diffusion in amorphous matrices were compared. First, an automatic sorption device was used to measure the water sorption kinetics of powders of maltodextrin DE21 and DE47 with defined shapes when equilibrating at different air relative humidity (0–60% at 25 °C). Calculation of water diffusion coefficients was done according to Crank’s and Weibull’s models, and it was not possible when powders undergo glass transition. In the second part of the study a thin film dryer was used to assess the drying kinetics of aqueous solutions of maltodextrin (DE 6-12-29-40). The Yamamoto’s model allowed calculating water diffusion as a function of water content and temperature, above and below glass transition temperature.     

Glass Transition and State Diagram for Jujube Powders With and Without Maltodextrin Addition

Both water activity and glass transition concepts were used for stability evaluation of jujube powder in this study. The water sorption behaviour at 25, 35 and 45 °C and the relationship between water content (X _w), glass transition temperature (T _g) and water activity (a _w) were investigated for jujube powder with and without the maltodextrin addition. Moisture sorption isotherms of different jujube powders were of type III and BET model was the best for fitting the experimental data. The equilibrium moisture content of jujube powder containing 20% maltodextrin at a given a _w was lower than that of pure jujube powder. However, temperature had no significant effect on the moisture sorption of jujube powders. Values of T _g of different jujube powders were obtained using differential scanning calorimetry and the glass transition line was fitted to the Gordon-Taylor model. A depression in T _g with increasing water content was observed. State diagrams of different jujube powders were established based on the moisture sorption isotherm and the glass transition curve. Results showed that jujube powders with and without maltodextrin addition were stable at 25 °C when the water content was lower than 0.0673 and 0.0566 g/g solid, respectively.     

The improving effect of spray-drying encapsulation process on the bitter taste and stability of whey protein hydrolysate

Although whey protein hydrolysate (WPH) possesses good physiological functionality, its bitter taste and hygroscopic property limit its direct utilization as food ingredient. The aim of this work was to encapsulate whey protein hydrolysate by spray drying using maltodextrin or maltodextrin/??-cyclodextrin mixture as wall materials to attenuate the bitter taste and enhance the stability of whey protein hydrolysate. Hygroscopicity, glass transition temperature, bitter taste, and morphology of non-encapsulated WPH and encapsulated WPH were evaluated. Solubility, particle size, bulk density, and moisture content were also measured. Compared with the non-encapsulated WPH, the encapsulated WPH exhibited significantly lower hygroscopicity and higher glass transition temperature. The bitterness of both maltodextrin-encapsulated WPH and maltodextrin/??-cyclodextrin-encapsulated WPH was significantly lower than that of the original non-encapsulated WPH. Morphological analysis by scanning electron microscopy showed that the microcapsules of the spray-dried encapsulated WPH were matrix-type with less link bridge and had a continuous wall with many concavities. In addition, encapsulation process did not exert negative effect on the solubility of whey protein hydrolysate. The results indicated that encapsulation with maltodextrin and ??-cyclodextrin as carriers was helpful to attenuate the bitter taste and enhance the stability of whey protein hydrolysate.     

Inulin and maltodextrin can replace fat in baked savoury legume snacks

A baked yellow split pea cracker was developed with fat replacement (0%, 25%, 50%, 75% and 100%) using inulin, hydroxypropyl methylcellulose and maltodextrin. Effects of fat replacement on physical (water activity, moisture content, colour and hardness), nutritional properties and consumer acceptance (nine‐point hedonic rating) of snacks were investigated. Water activity (0.15–0.32) and moisture (1.28–3.16%) readings were consistent, and products were considered shelf stable. High levels of fat replacement (100%) were detrimental to snack colour and hardness. Snacks with 75% fat replacement using inulin and maltodextrin received similar mean overall acceptability scores (6.40 ± 1.36 and 6.26 ± 1.37, respectively) to the control and a similar commercial product. These snacks were eligible to claim that they were a ‘good source’ of protein (requirement; ≥10 g per serve) and an ‘excellent source’ of dietary fibre (requirement; ≥7 g per serve) while providing ‘reduced’ fat content (≤25% than reference food) based on the Australian Food Standards Code.