Spray Drying of Spinach Juice: Characterization,Chemical Composition,and Storage

The 1st aim of this study is to determine the influence of inlet and outlet air temperatures on the physical and chemical properties of obtained powders from spinach juice (SJ) with 3.2 ± 0.2 °Brix (°Bx). Second, the effect of 3 different drying agents (maltodextrin, whey powder, and gum Arabic) on the same properties was investigated for the selected inlet/outlet temperatures (160/100 °C) which gives the minimum moisture content and water activity values. For this purpose, the total soluble solid content of SJ was adjusted to 5.0 ± 0.2 °Bx with different drying agents. Finally, the effects of different storage conditions (4, 20, and 30 °C) on the physical and chemical properties of spinach powders (SPs) produced at selected conditions were examined. A pilot scale spray dryer was used at 3 different inlet/outlet air temperatures (160 to 200 °C/80 to 100 °C) where the outlet air temperature was controlled by regulating the feed flow rate. Results showed that the moisture content, water activity, browning index, total chlorophyll, and total phenolic contents of the SP significantly decreased and pH and total color change of the SP significantly increased by the addition of different drying agents (P < 0.05). In addition, the changes in the above‐mentioned properties were determined during the storage period, at 3 different temperatures. It was also observed that the vitamin C, β‐carotene, chlorophyll, and phenolic compounds retention showed first‐order degradation kinetic with activation energy of 32.6840, 10.2736, 27.7031, and 28.2634 kJ/K.mol, respectively.     

Foam‐Mat Freeze‐Drying of Bifidobacterium longum RO175: Viability and Refrigerated Storage Stability

Foaming as a pretreatment was used prior to freeze‐drying of Bifidobacterium longum RO175 to investigate the potential acceleration of the drying rate and increase in microorganism viability after the process. A study on storage of foamed and nonfoamed freeze‐dried products at 4 °C completed this study. B. longum RO175 in foamed medium could be freeze‐dried in 1/7 to 1/4 of the time required for nonfoamed suspensions. In addition, foamed suspensions presented higher viability immediately after freeze‐drying (13.6% compared to 12.81 % or 11.46%, depending on the cryoprotective media). Refrigerated storage led to a reduction in B. longum RO175 viability for all tested protective agents (foamed and nonfoamed). No correlation between glass transition temperature and stability of probiotic powders was observed during storage. In addition, lower viability after 56 d of storage was observed for foamed materials, probably due to foam porous structure and higher hygroscopicity, and oxygen presence and moisture pickup during storage.     

Microencapsulation of Corn Wastewater (Nejayote) Phytochemicals by Spray Drying and Their Release Under Simulated Gastrointestinal Digestion

Corn lime cooking generates a large amount of wastewater known as nejayote that is composed of suspended solids and solubilized phytochemicals. Spray drying can be an alternative to recover bioactive molecules, such as ferulic acid, from nejayote. Besides the yield, the physicochemical properties (solubility, water activity, pH, moisture, hygroscopicity, total phenolic content, and distribution of free and bound hydroxycinnamic acids) of spray‐dried nejayote powders were analyzed. The powders were obtained at 200 °C/100 °C or 150 °C/75 °C (inlet/outlet) air temperatures with the addition of maltodextrin (MD) or 2‐hydroxypropyl‐beta‐cyclodextrin (HBCD) as encapsulating agents. Even when no carrier agent was used, a spray‐dried nejayote powder was produced. The use of MD or HBCD as carrier increased the yield from 60.26% to 68.09% or 71.83%, respectively. As expected, a high inlet temperature (200 °C) allowed a satisfactory yield (>70%) and a low powder moisture (2.5%) desired by the industry. Water activity was reduced from 0.586 to 0.307 when HBCD was used in combination with a drying inlet temperature of 150 °C; and from 0.488 to 0.280 when the inlet temperature was set at 200 °C. Around 100% bioaccessibility of the compounds was observed after in vitro digestion. The addition of HBCD increased the release time (P < 0.05). Under simulated physiological conditions, there was no reduction of total phenolics, suggesting a good stability. This paper showed the feasibility to engage the spray drying technology to the corn industry to minimize their residues and reuse their by‐products.     

Stability of microencapsulated lactic acid bacteria under acidic and bile juice conditions

The probiotic strains Lactobacillus brevis CCMA1284 and Lactobacillus plantarum CCMA0359 were microencapsulated by spray drying using different matrices – whey powder (W), whey powder with inulin (WI) and whey powder with maltodextrin (WM). Viability of the microencapsulated strains in acid and bile juices and during 90 days of storage (seven and 25 °C) was evaluated. The two strains exhibited high encapsulation efficiency (> 86%) by spray drying. The different matrices maintained L. plantarum viability above six log CFU g⁻¹ at 7 °C for 90 days, whereas similar results for L. brevis were observed only for W. The use of inulin as matrix of encapsulation did not enhance bacterial viability in the evaluated conditions. In general, the use of W and WM as matrices was effective for L. plantarum viability. However, only W was effective for L. brevis in the evaluated conditions. The spray drying technique was successfully adopted for the encapsulation of L. plantarum CCMA0359 and L. brevis CCMA1284 strains.     

The Viability of Lactobacillus rhamnosus GG and Lactobacillus acidophilus NCFM Following Double Encapsulation in Alginate and Maltodextrin

Lactobacillus rhamnosus GG (LGG) and Lactobacillus acidophilus NCFM (LNCFM) were encapsulated in alginate microgel particles (microbeads) by a novel dual aerosols method. The encapsulated probiotics in microbead gel matrix were further stabilized in maltodextrin solids by either spray or freeze-drying to form probiotic microcapsule powders. The free cells of probiotics were also sprayed and freeze-dried in maltodextrin only without microgel encapsulation. After rehydration of microgel-encapsulated powder, gel particles regained their shape. There was no difference in the loss of viability between encapsulated and unencapsulated probiotics during spray drying or freeze-drying. For LNCFM, spray-dried bacteria with or without gel encapsulation exhibited less death (3.03 and 3.07 log CFU/g reduction, respectively) than those of freeze-dried bacteria (4.36 and 4.89 log CFU/g reduction, respectively) after 6 months storage at 4 °C. The same trend was also observed in spray-dried LGG without gel encapsulation which showed 5.87 log CFU/g reduction in viability after 6 months at 4 °C; however, freeze-dried LGG without gel encapsulation exhibited a rapid reduction in viability of 5.91 log CFU/g within just 2 months. Gel-encapsulated LGG which was freeze-dried exhibited less death (3.32 log CFU/g reduction) after 6 months at 4 °C. This work shows that spray drying results in improved subsequent probiotic survivability compared to freeze-drying and that alginate gel encapsulation can improve the survivability following freeze-drying in a probiotic-dependent manner.     

Effects of Drying Conditions on Water Sorption and Phase Transitions of Freeze-Dried Horseradish Roots

The water sorption isotherms for freeze-dried horseradish roots (Armoracia rusticana) were determined using the interval sorption technique, and the thermal behavior of dried and rehumidified products was analyzed using differential scanning calorimetry. The hygroscopicity of the dried material increased when the surface temperature during freeze-drying was increased from 20°C to 60°C. Both sorption and thermal data showed that drying at high surface temperatures affected the physical structure of the material, resulting in increased water adsorption, decreased glass transition temperature, and increased unfreezeable water content. Water sorption isotherms and thermal data can be used to determine the proper drying and storage conditions for horseradish roots.     

Microencapsulated Lactobacillus rhamnosus GG powders: relationship of powder physical properties to probiotic survival during storage

Freeze-dried commercial Lactobacillus rhamnosus GG (LGG) were encapsulated in an emulsion-based formulation stabilized by whey protein and resistant starch and either spray-dried or freeze-dried to produce probiotic microcapsules. There was no difference in loss of probiotics viability after spray drying or freeze drying. Particle size, morphology, moisture sorption, and water mobility of the powder microcapsules were examined. Particle size analysis and scanning electron microscopy showed that spray-dried LGG microcapsules (SDMC) were small spherical particles, whereas freeze-dried LGG microcapsules (FDMC) were larger nonspherical particles. Moisture sorption isotherms obtained using dynamic vapor sorption showed a slightly higher water uptake in spray-dried microcapsules. The effect of water mobility, as measured by nuclear magnetic resonance (NMR) spectroscopy, at various water activities (a(w) 0.32, 0.57, and 0.70) and probiotic viability during storage at 25 °C was also examined. Increasing the relative humidity of the environment at which the samples were stored caused an increase in water mobility and the rate of loss in viability. The viability data during storage indicated that SDMC had better storage stability compared to FDMC. Although more water was adsorbed for spray-dried than freeze-dried microcapsules, water mobility was similar for corresponding storage conditions because there was a stronger water-binding energy for spray-dried microcapsule. This possibly accounted for the improved survival of probiotics in spray-dried microcapsules.     

Spray drying conditions for orange juice incorporated with lactic acid bacteria

This work aimed to develop an orange juice powder by spray drying with lactic acid bacteria (Lactobacillus plantarum 299v and Pediococcus acidilactici HA‐6111‐2), testing their survival both during drying and storage (room temperature and 4 °C). Initially, the best conditions for spray drying were chosen to allow the best survival of each LAB: (i) inlet air temperature of 120 °C and (ii) 0.5:2 ratio of the orange juice soluble solids and drying agent added (prebiotics: 10 DE maltodextrin or gum Arabic). Survival of LAB was not affected by drying process, and it was higher when cultures were stored at 4 °C. A slightly higher protection was conferred by 10 DE maltodextrin, in the case of L. plantarum and at 4 °C. Pediococcus acidilactici was more resistant during storage at 4 °C, with logarithmic reductions lower than 1 log‐unit. It was demonstrated that it is possible to produce a functional nondairy product, orange juice powder supplemented with prebiotic compounds, containing viable LAB for at least 7 months, when stored at 4 °C.     

Spray drying of red (Hylocereus polyrhizus) and white (Hylocereus undatus) dragon fruit juices: physicochemical and antioxidant properties of the powder

This study aims to investigate physical stability and antioxidant properties of spray‐dried red (Hylocereus polyrhizus) and white (Hylocereus undatus) dragon fruit powder upon storage at various relative humidity (RH). Inlet air temperatures of 120 °C (red dragon fruit) and 110 °C (white dragon fruit) as well as maltodextrin concentration of 30% (w/v) were selected as the spray drying conditions as powder was obtained at these minimum conditions. The powder was ranging from 3 to 7 μm in particle size with spherical morphology. The powder had lower antioxidant content and antioxidant activities compared with the control before spray drying. Storage of powder at 43%, 54% or 75% RH at 25 °C for 25 days resulted in structural changes correlating to the depression of glass transition temperatures (T_g) to below storage temperature. At 33% RH, no visible structural changes were observed. Antioxidant properties of the powder remained unchanged after 25 days' storage at the studied RHs.     

Survival of Lactic Acid Bacteria during Spray Drying of Plain Yogurt

Survival of Streptococcus salivarius subsp. thermophilus and Lactobacillus debrueckii subsp. bulgaricus was determined under various processing conditions for spray drying. Numbers of both microorganisms decreased with increased outlet or inlet air temperature, and atomizing air pressure. Outlet air temperature was a major parameter affecting number of survivors. Suitable conditions were inlet air 160°C, outlet air 60°C, atomizing air pressure 98 kPa, hot air flow 0.28 m³/ min, and feed temperature 30°C. Spray-dried yogurt powder showed lower survival for S. thermophilus and similar survival for L. bulgaricus as compared to freeze-dried powder.     

Spray Drying, Freeze Drying, or Freezing of Three Different Lactic Acid Bacteria Species

Lactococcus lactis ssp. cremoris D11, Lactobacillus casei ssp. pseudo-plantarum UL137, and Streptococcus thermophilus CH3TH, were separately frozen, freeze dried or spray dried, and tested for survival and lactic acid production before and after processing. Virtually all cells survived freezing. Of the survivors, 60 to 70% survived the dehydration step of freeze drying. In contrast to freezing and freeze drying, spray drying caused considerable delay in lactic acid production and reduction in survival. After spray drying, survival was greatest for S. thermophilus and lowest for Lc. cremoris.     

Spray Drying of Lactococcus lactis ssp. lactis C2 and Cellular Injury

Starter cultures were spray-dried at five outlet-air temperatures using four concentrations of cells in the feed solution. Powders made using the lowest outlet-air temperature and the highest cell concentration had the highest viability. Storage at 4°C for 3 mo caused a 34–86% loss of viability. Cellular injury resulted from dehydration, and exposure to high temperatures in the atomizer and during droplet drying. Lactic acid production was similar for frozen, freeze-dried and spray-dried cultures made from a single cell paste. The lag time before lactic acid production was apparently an inherent characteristic of each specific cell paste.     

The nutritive value of porcine blood plasma concentrates prepared by ultrafiltration and spray Drying

Concentrated solutions of porcine blood plasma proteins, prepared by centrifugation and ultrafiltration⁴ were spray dried directly at air inlet temperatures of 154, 170.3, 225 and 243.2 °C. Spray dried concentrates contained ca 86–90% protein, ca 2–7% moisture and ca 5% minerals. The overall amino acid composition of the plasma proteins compared favourably with that of FAO whole egg protein.¹² Although the values of essential amino acids generally fell below the egg values, the only serious limitations were in the content of isoleucine (less than half of the egg value). The chemical score (CS) and essential amino acid index (EAAI) were 49.1 and 70.1 respectively. Rats fed on a diet containing plasma concentrate as the sole protein source showed a net weight increase. NPU carcass for plasma protein was 65.8 ± 1.9 compared with a value of 72.1 ± 0.4 for a casein control. An inverse correlation between denaturation status of plasma proteins and spray drying temperature was found. The percent denaturation as measured on pH 4.0 filtrates increased from 8.4% at an air inlet temperature of 154 °C to 48.6% at a temperature of 243.2 °C. A similar inverse relationship was found between the available lysine content of plasma proteins and spray drying temperature. A maximum decrease in percent lysine availability of 16% was found at an air inlet drying temperature of 243.4 °C.     

Physicochemical properties and storage stability of spray‐dried soya bean sprout extract

Amylase is a very important enzyme due to its wide food applications. To preserve amylase activity in soya bean sprout extract (SSE), SSEs were spray‐dried with 10% maltodextrin and 0–3% alginic acids, and their physicochemical properties and storage stability were compared with freeze‐dried one. SSE exhibited maximum amylase activity at pH 7.0 and 60 °C, with the most active substrate specificity towards soluble starch. Spray‐dried SSEs exhibited higher water solubility index (WSI) and in vitro relative amylase activity but lower water vapour sorption (WVS) and smaller particle size than freeze‐dried SSE. For spray‐dried SSEs, particle size, WSI and in vitro relative amylase activity increased while WVS decreased with increasing % alginic acid. This study demonstrated that spray drying of SSE, especially with 10% maltodextrin and 2% alginic acid, was effective in keeping amylase active and stable during 7‐week storage at room temperature (25 °C).     

Impact of chitosan and oregano extract on the physicochemical properties of microencapsulated fish oil stored at different temperature

Fish oil is an excellent source of omega-3 fatty acids and is easily susceptible to oxidation. Microencapsulation is a commonly employed technique to protect fish oil against oxidation. In the present study, the potential of chitosan in combination with bovine gelatin and maltodextrin as wall material for microencapsulation of fish oil by spray drying was evaluated. To improve the oxidative stability of the fish oil microencapsulates, oregano (Origanum vulgare L) extract was added at 0.50 g/100 g of emulsion. The spray-dried powder showed a moisture content of 2.8 – 3.2 g/100 g of spray-dried powder. The powder contained spherical microparticles with different sizes as indicated by scanning electron microscope images. Encapsulation efficiency of microencapsulates ranged between 68.94% and 81.88%. Differential scanning calorimetry and Fourier-transformed infrared spectroscopy analysis of microencapsulates revealed the possible structural stabilization of core and wall material. The oxidative stability of fish oil microencapsulates were monitored under three different temperature (60°C, 28 ± 2°C, and 4°C). Incorporation of oregano extract minimized the generation of secondary and tertiary oxidation products as indicated by lower peroxide value and thiobarbituric acid reactive substance values compared to control. Overall, the results suggested that combination of chitosan along with bovine gelatin and maltodextrin as wall material improved the surface morphology of the microparticle and encapsulation efficiency, whereas incorporation of oregano extract in fish oil before spray drying enhanced the oxidative stability during storage.     

Microwave‐Osmotic/Microwave‐Vacuum Drying of Whole Cranberries: Comparison with Other Methods

A novel drying method for frozen‐thawed whole cranberries was developed by combining microwave osmotic dehydration under continuous flow medium spray (MWODS) conditions with microwave vacuum finish‐drying. A central composite rotatable design was used to vary temperature (33 to 67 °C), osmotic solution concentration (33 to 67 °B), contact time (5 to 55 min), and flow rate (2.1 to 4.1 L/min) in order to the determine the effects of MWODS input parameters on quality of the dried berry. Quality indices monitored included colorimetric and textural data in addition to anthocyanin retention and cellular structure. Overall it was found that the MWODS‐MWV process was able to produce dried cranberries with quality comparable to freeze dried samples in much shorter time. Additionally, cranberries dried via the novel process exhibited much higher quality than those dried via either vacuum or convective air drying in terms of color, anthocyanin content, and cellular structure.     

Crystallization and Drying in Thin Sucrose Films During Panning

Sucrose crystallization in thin films (50–55 μm) was studied, using a videomicroscopy technique, at conditions encountered during hard panning processes. No nucleation occurred in unseeded films, while a linear increase in seeded crystals occurred during drying. Crystal growth rate increased with temperature (25–30°C) and with air velocity (2.4–12.5 m/sec), but did not change with varying sucrose concentrations (70–76% w/w) and relative humidities (0–66% at 30°C). FD & C Yellow No. 5 food coloring in the dye form (0.05–0.5 g/100 mL) showed no effects while similar concentrations in the lake form inhibited crystal growth rate.     

Drying and storage of crude β-galactosidase extracts from Lactobacillus delbrueckii ssp. bulgaricus 11842

The retention of β-galactosidase activity in crude cellular extract (CCE) preparations from Lactobacillus delbrueckii subsp. bulgaricus ATCC 11842 was investigated after spray drying at three different outlet air temperatures (40, 50 or 60 °C), freeze drying, and after 30 days storage. Lactose, skim milk and whey protein preparations in concentrations ranging from 5 to 30% (w/w) were used as drying adjuncts. To further investigate the protective role of sugars in the enzyme activity preservation, cellobiose and sucrose were also employed in 5 and 10% concentrations during spray-drying at 60 °C or freeze-drying. The addition of lactose or skim milk in all examined concentrations resulted in significantly (P<0.05) higher β-galactosidase activity retention in comparison to all other CCE spray dried at 60°C. The effect was less pronounced at lower spray drying temperatures and increased whey protein concentrations, especially during freeze drying, when almost complete recovery of the enzyme activity upon reconstitution was achieved. Cellobiose provided less β-gal protection in comparison to lactose or sucrose. Lactose was more effective than sucrose at 5% concentration, but both sugars were equal at 10%. The β-gal activity retention in dry CCE preparations during storage at 7 °C over 30 day period was related to the initial water activity; higher initial a_w of powders obtained at lower spray drying temperature was correlated with significant (P<0.05) β-gal activity loss. Freeze dried and spray dried (60 °C) preparations were more stable in comparison to all other samples, retaining high β-gal activity during storage up to 30 days.     

Determination of ideal water activity and powder temperature after spray drying to reduce Lactococcus lactis cell viability loss

Spray drying presents a promising technology for preserving bacteria despite a low survival rate of heat-sensitive cultures when subjected to the drying process. The aim of this study was to determine the ideal powder parameters [water activity (Aw) and temperature (T°C_powder)] needed to produce dehydrated Lactococcus lactis ssp. lactis with a high viability after drying. Cell concentrates injected into a spray dryer using varying cell concentrate flow rates (F_concentrate = 0.3 to 1.0 kg/h), inlet air temperatures (T°C_{inlet air} = 115 to 160°C), and outlet air temperatures (T°C_{outlet air} = 70 to 115°C) resulted in powders with different values of Aw and T°C_powder, and levels of cell viability loss. Lower cell viability reduction (∼0.43 log cycles) was obtained in conditions of Aw = 0.198 and T°C_powder = 52°C, which can be met by using T°C_{inlet air} ∼126°C and T°C_{outlet air} = 88.9°C regardless of F_concentrate values. After 60 d of storage at room temperature, cell population varied from 7.0 × 10⁵ to 1.1 × 10⁸ cfu/g. The initial powder Aw had no influence on cell death rate, but T°C_powder influence was observed. The approach adopted in this study can be applied to other bacteria or spray dryer equipment to determine optimal drying conditions.     

Effects of Drying,Packaging, and Temperature on the Quality of Fried Onion Slices

Abstract: Onion is used widely as a condiment for meat and other types of food in Iran. Because of the high sensitivity of this product to storage conditions and having not enough storage under controlled atmosphere (CA), the effects of drying method, packaging, and temperature during storage on thin slices of fried red Azershahr variety onion were investigated. To prepare this processed food with excellent organoleptic properties and useful in the food service industry onions were sliced (2 mm), deep-fried with corn frying oil in a batch fryer at 150 °C, and dried to a water content of 3-4% in a hot-air dryer at 70 °C for 24 h and a microwave system. Samples were packed in aluminum foil, which was purged by nitrogen gas, and cellophane-sealed with thermal sewing. Then these samples were kept for one year at laboratory temperature and in a freezer at −18 °C. During the storage time the moisture content, peroxide value, vitamin C content, total microbial count (TMC), and organoleptic characteristics of the samples were analyzed every 2 mo. The results of microbial analyses indicated that after 6 mo all of the samples had higher TMCs than the permission limits so the expiration date was set before that. The moisture contents and peroxide values showed a noticeable increase, probably due to seal failure, whereas vitamin C decreased up to 66% during storage. The loss of sensory properties was parallel to the microbial and chemical results. The findings revealed that the best sample was oven-dried, packed in aluminum foil under inert gas, and kept in a freezer (OAF) up to 6 mo.