Viability of Lactobacillus plantarum TISTR 2075 in Different Protectants during Spray Drying and Storage

Spray drying was applied for the production of Lactobacillus plantarum TISTR 2075 powder using maltodextrin as the carrier. A survival rate of 0.85% was achieved for this probiotic bacteria after spray drying. To improve the survival of this strain during the spray-drying process and storage, various protectants were added before drying. These included protein, trehalose, fibersol, ascorbic acid, isomalt, palatinose, and gum acacia. The results indicated that trehalose and protein (a combination of soy protein isolate and milk protein concentrate) significantly (P < 0.05) enhanced the viability during spray drying, with survival rates of 57.70 and 25.31%, respectively. Survival of the dried strain was also monitored over a period of 12 months’ storage at 4 and 25°C. Higher temperature induced lower viability of the strain in all protectants during this long-term storage. Accelerated storage tests using temperatures of 37, 45, 60, and 80°C were also applied to the spray-dried powders. A temperature-dependent prediction model was developed to determine the viability of the spray-dried L. plantarum TISTR 2075 in different protectants for long-term storage.     

Influence of wall material on production of spray dried Lactobacillus plantarum NRRL B-4496 and its viability at different storage conditions

The objectives of this study were to evaluate the spray drying conditions to produce Lactobacillus plantarum powders and to investigate their viability at different storage conditions. L. plantarum NRRL B-4496 was spray dried with high maize starch, maltodextrin, or gum arabic and stored under 97 and 10% vacuum at refrigerated (4°C) and room (23°C) temperatures. Probiotic solutions mixed with the different wall materials had different mass flow rates (kg/h) which produced as a result different evaporation rate values for the production of the probiotic powders. High maize starch and gum arabic were better protective agents than maltodextrin. L. plantarum encapsulated with high maize starch, packed under 97% vacuum, and stored at refrigerated temperature maintained the highest cell viability during 60 days of storage (0.14 log reduction).     

Sodium Humate as a Promising Coating Material for Microencapsulation of Beauveria bassiana Conidia Through Spray Drying

Microencapsulation of Beauveria bassiana (Bb) conidia with sodium humate (SH) was undertaken successfully through spray drying at a high inlet air temperature of 175°C with corresponding outlet air temperature of 86.5 ± 1.3°C using 0.2% SH. The obtained product was a free-flowing, dark-brown powder containing microcapsules of Bb conidia coated with sodium humate (Bb-SH). These microcapsules measured 2.47–3.57 µm and possessed an uneven, fluffy surface. The colony-forming units (CFU) of Bb-SH microcapsules spray-dried at 175°C were 21.54 LCFUg^?1, on par with 21.59 LCFUg^?1 for Bb conidial powder not subjected to spray drying. Bb-SH microcapsules resulted in a high mortality of 93.0% against six-day-old Helicoverpa armigera larvae within five days after treatment. Bb-SH microcapsules readily dispersed in water, releasing sodium humate from the conidial surface. Germination of conidia was not affected by sodium humate as visualized by scanning electron microscopy of the cuticular surface of treated larvae. Bb-SH microcapsules showed good viability (21.11 LCFUg^?1) at the end of six months of storage at room temperature (～30°). Thus, sodium humate is a promising biopolymer for encapsulation of Bb conidia for extended shelf-life at room temperature.     

Yogurt Starter Obtained from Lactobacillus plantarum by Spray Drying

Probiotics have been known to mankind for many centuries and the quest for its health benefits is increasing in this century through focused research on various food products. Researchers have a growing interest in probiotics starter cultures for fermented milk products. Lactobacillus plantarum MA2 was isolated with good fermentation characteristics from Tibet kefir and identified by morphological, physiological, biochemical, and 16S rDNA sequence analysis. This work focused on the preparation of MA2 starter cultures by spray drying and compared the physiological activity of starter cultures to that of freeze-dried powder. The experimental results showed that the best spray-drying conditions were as follows: inlet air temperature of 148.9°C, raw material flow rate of 61.5 mL/h, and a protectant : cell ratio of 3:1. The viable cells of spray-dried starter cultures was 1.82 × 10⁹ colony-forming units (cfu)/g. The in vivo experiments revealed that after the spray-drying process, starter cultures of MA2 had good milk curdling and cholesterol removal ability (45.5%), which was very close to the fresh bacteria broth (46.8%) and freeze-dried starter cultures (46.1%). Furthermore, the spray-dried starter cultures had good stability during storage at 4°C. These results showed that the modified spray-drying process achieved the intended purpose of efficient preparation of the yogurt starter cultures.     

Narrow tube spray drying

Spray drying conventionally necessitates relatively large or elongated drying chambers. The present study examined the possibility in shrinking the spray drying chamber into narrow tube-like geometry. The key was in utilizing fine droplets which had low transport response time. A narrow copper/steel tube spray dryer (internal diameters between 12.7 and 48.0 mm) was constructed and was fitted with a two-fluid atomizer producing droplets in the size range smaller than 10 µm. Maltodextrin, lactose, and sucrose were spray-dried. The narrow tube approach allowed direct manipulation of the drying conditions via heating or cooling along the wall of the tube. This form of manipulation in the drying conditions, surprisingly, resulted in very distinctly crystalline spray-dried sucrose particles. The tube spray dryer was further modified with a long coiled-up tube, extending the particle residence time with minimal space requirements. Endoscopic analysis revealed that particle deposition within the tube resembled loosely attached particle and granules. The tube spray drying concept can potentially be used to provide precise control of the particle drying history along the length of the drying chamber, not limited to the control of the drying conditions at the inlet or outlet of a spray dryer.     

Effect of Pretreatments and Drying Methods on the Properties and Fishy Odor/Flavor of Gelatin from Seabass (Lates calcarifer) skin

Effects of different pretreatments of seabass skin and various drying methods on properties and fishy odor/flavor of resulting gelatin were evaluated. All gelatins contained α- and β-chains as the predominant components. Generally, a higher gel strength was found in the freeze-dried gelatin, compared with spray-dried counterpart (p < 0.05). Gel strength of gelatin decreased as the inlet temperature for spray drying increased (p < 0.05). All gelatin samples had creamy whitish color but became more yellow as the inlet temperature for spray drying increased. All gelatin gels were sponge- or coral-like in structure. Gelatin from skin pretreated with citric acid had lower fishy odor/flavor than that from skin pretreated using acetic acid. The lower fishy odor/flavor with coincidentally lower abundance of volatile compounds, including aldehydes, ketones, and alcohols, etc., was found in gelatin obtained by spray drying, in comparison with its freeze-dried counterpart. The lower fishy odor/flavor in spray-dried gelatin was in accordance with the lower thiobarbituric acid reactive substances and peroxide values. Thus, spray drying in conjunction with an appropriated pretreatment could be an effective method for production of gelatin with negligible undesirable fishy odor and flavor.     

A novel insight to screen the optimal spray-drying protectants and parameters for manufacturing lactic acid bacteria preparations

Abstract

This study constructed a β-galactosidase (β-gal) liposome model instead of bacterial cells to optimize spray-drying protectants and parameters. The screened protectant combination consisted of 35?g/L monosodium glutamate, 50?g/L sucrose, and 35?g/L maltodextrin. The optimal parameters for spray drying were 130?°C inlet air temperature, 7.5?mL/min feed flow rate, and 150?mL optimal protectant combination. The viability of the five lactic acid bacteria strains spray-dried with the optimized protectant and parameters was over 50%. Lactobacillus helveticus strain LH-9’s mechanism of resistance to spray-dry treatment was investigated in the presence of the optimal protectant combination.     

Whey Protein-Pullulan (WP/Pullulan) Polymer Blend for Preservation of Viability of Lactobacillus acidophilus

In this study, whey protein isolate-pullulan (WP/pullulan) microspheres were developed to entrap the probiotic Lactobacillus acidophilus NRRL-B 4495 by spray-drying technique. Microcapsules were analyzed for physicochemical characteristics including morphology, particle size, moisture content, water activity, dissolution time, and color properties. Results revealed that microcapsules were spherical in shape and obtained particle sizes between 5 and 160 µm, with an average size of around 50 µm. Blending pullulan with WP provided enhanced survival of probiotic bacteria during spray drying with a final viable cell number of 8.81 log CFU/g of microcapsule. Encapsulated probiotics were also found to have significantly (p ≤ 0.05) higher survived cell numbers compared to free probiotics under detrimental gastrointestinal conditions. Moreover, dissolution analysis suggested that protein-polysaccharide powdered microcapsules showed pH-sensitive dissolution properties in simulated gastric juice and simulated intestinal juice.     

Spray Drying of Lactobacillus plantarum WCFS1 Guided by Predictive Modeling

Shelf life of probiotic microorganisms can be retained by drying. Spray drying is an economically interesting alternative to freeze drying with that respect. However, the viability can decrease due to the drying process and testing it is laborious and expensive. This research shows that the viability of Lactobacillus plantarum WCFS1 during pilot scale drying can be predicted with kinetics gathered at a single droplet level. Using this approach, it could be demonstrated that the viability of L. plantarum WCFS1 during spray drying is mainly determined by the combination of temperature and moisture content during the first 0.5 seconds after atomization. The combination of a high moisture content and a high temperature appeared most detrimental to the residual viability. Moreover, it was found to be important to take into account the particle size distribution during atomization when predicting viability, since this has a large effect on the moisture content during this first 0.5 seconds. Finally, it was observed that shelf life during storage was mainly determined by the moisture content of the powder. A lower moisture content resulted in a higher viability. Above a moisture content of 6%, shelf life stability rapidly decreased in the applied maltodextrin (DE = 16) matrix.     

Hydroxypropyl Methylcellulose Reduces Particle Adhesion and Improves Recovery of Herbal Extracts During Spray Drying of Chinese Herbal Medicines

The effectiveness of hydroxypropyl methylcellulose (HPMC) as an anti-adherent during spray drying of traditional Chinese herbal extracts was explored. A small amount of HPMC (minimum concentration 8%) was sufficient to overcome problematic particle adhesion, whereas a large amount of maltodextrin (50%) was required for the same effect. HPMC exerted a strong anti-adhesive effect that was independent of the type of HPMC, raw materials used, and the process used to synthesize HPMC. The anti-adhesion mechanism was studied through an analysis of the surface tension of the prepared solutions before spray drying, the glass transition temperature (T _g ), and X-ray photoelectron spectroscopy (XPS) of spray-dried powders. The T _g of powders containing more than 8% HPMC was approximately 40°C and did not increase linearly with the HPMC concentration. The surface tension of Crataegi fructus extract was 54.1 ± 0.2 mN/m and further decreased to 46.6 ± 0.2 mN/m upon addition of HPMC to 24%. When the concentration of HPMC increased to 8%, potassium could not be detected on the surface of dried powders by XPS. These results suggest that modification of the surface properties of sprayed droplets/particles by HPMC increased the HPMC surface coverage of the particles and reduced adhesion during spray drying.     

Surface Stickiness of Drops of Carbohydrate and Organic Acid Solutions During Convective Drying: Experiments and Modeling

Abstract

Drying kinetics of low molecular weight sugars such as fructose, glucose, sucrose and organic acid such as citric acid and high molecular weight carbohydrate such as maltodextrin (DE 6) were determined experimentally using single drop drying experiments as well as predicted numerically by solving the mass and heat transfer equations. The predicted moisture and temperature histories agreed with the experimental ones within 6% average relative (absolute) error and average difference of ± 1°C, respectively. The stickiness histories of these drops were determined experimentally and predicted numerically based on the glass transition temperature (T _g ) of surface layer. The model predicted the experimental observations with good accuracy. A nonsticky regime for these materials during spray drying is proposed by simulating a drop, initially 120 µm in diameter, in a spray drying environment.     

Microencapsulation of Ketoprofen in Blends of Acrylic Resins by Spray Drying

Microparticles of ketoprofen entrapped in blends of acrylic resins (Eudragit RL 30D and RS 30D) were successfully produced by spray drying. The effects of the proportion ketoprofen : polymer (1:1 and 1:3) and of spray-drying parameters (drying gas inlet temperatures of 80 and 100°C; microencapsulating composition feed flow rates of 4 and 6 g/min) on the microparticles properties (drug content, encapsulation efficiency, mean particle size, moisture content, and dissolution behavior) were evaluated. Differential scanning calorimetry (DSC) thermograms and X-ray diffractograms of the spray-dried product, the free drug, and the physical mixture between the free drug and spray-dried composition (blank) were carried out. Microparticles obtained at inlet temperature of 80°C, feed flow rate of 4 g/min, and ketoprofen : acrylic resin ratio of 1:3 presented an encapsulation efficiency of 88.1%, moisture content of 5.8%, production yield around 50%, and a higher reduction in dissolution rate of the entrapped ketoprofen. Sigmoidal shape dissolution profiles were presented by the spray-dried microparticles. The dissolution profiles were relatively well described by the Weibull model, a showing high coefficient of determination, R ², and a mean absolute error between experimental and estimated values of between 4.6 and 10.1%.     

Optimization of Spray Drying of Ginger Extract

Ginger (Zingiber oficinale) has many applications in the food and pharmaceutical sectors as an additive in a number of commercial foods and beverages. It is valued both for its aromatic volatile constituents and its spicy, pungent constituents. Ginger, if taken in a proper dosage, has high medicinal value because it is useful in preventing motion sickness and has a calming effect on upset stomach. Dehydration helps to achieve longer shelf life and easier transportation and storage, enabling wider distribution of the product. But it is important to retain the 6-gingerol, the active component, during drying of ginger extract. The present work pertains to the optimization of spray drying of ginger extract using response surface methodology (RSM). A central composite method was used to design the experiments. Different parameters investigated include inlet temperature (120–160°C), air flow rate (40–60 Nm³/h), feed rate (2.5–4 mL/min), and atomization pressure (1.5–2.25 kg/cm²). Optimum drying conditions for spray drying were decided on the basis of different responses such as moisture content, water activity (a_w), flowability, porosity, and percentage retention of gingerol.     

The Efficacy of Chlorinated Water Treatments in Minimizing Yeast and Mold Growth in Fresh and Semi-dried Tomatoes

Abstract

A key problem with dried tomatoes for the industries is that the products tend to have limited shelf-life due to yeast and mold growth. This study was undertaken to evaluate the efficacy of chlorine treatments on minimizing yeast and mold populations on fresh and semi-dried tomatoes. Tomatoes were inoculated with molds (4.2 log CFU/g) from contaminated pack of semi-dried tomatoes. These inoculated tomatoes were then treated by washing with water (control) and concentrations of 50, 100, and 200 ppm of chlorinated water for specific length of time (1, 5, and 10 min), and finally analyzed for yeast and mold populations. In this study, the results showed that the maximum log reduction of yeast and mold cells on tomato surface was found to be chlorinated water with a concentration of 200 ppm. At this concentration, washing for 5 and 10 min resulted in 1.7 log reduction and 3.1 log reduction in yeast and mold growth respectively. This was significant (P<0.01) as compared with washing with tap water (control). Drying at 60°C further reduce the microbial load of these pre-treated tomatoes. Results showed that there were reductions in three of the twelve runs while seven of the runs demonstrated an increase in microbial load. This finding is important as it demonstrated that when using a typical drying temperature of 60°C, if the initial microbial load is high, there is a risk that the dehydrator can act as an incubator for more microbial growth. This finding also demonstrated the importance of pretreatment to reduce the initial microbial load before drying commences.     

Physicochemical Properties of Encapsulated Red Raspberry (Rubus idaeus) Powder: Influence of High-Pressure Homogenization

Encapsulated red raspberry (Rubus idaeus) powders with gum arabic were produced using a spray-drying method. The raspberry puree samples were treated with and without high-pressure homogenizers prior to spray drying. The physicochemical properties of spray-dried raspberry powders were analyzed. The median particle size (X ₅₀) of raspberry powder produced with high-pressure homogenized puree (14.6 µm) was smaller than raspberry powder produced without high-pressure homogenization applied to puree (18.3 µm). Glass transition temperatures and water contents of encapsulated raspberry powders were not significantly different (p > 0.05) at equivalent water activities. High-pressure homogenization of puree resulted in greater apparent density and porosity for encapsulated raspberry powder. Greater particle size resulted in higher hygroscopicity and water solubility index (WSI) for encapsulated raspberry powder produced without high-pressure homogenization of puree. Anthocyanins concentration was greater in raspberry powder pretreated with high-pressure homogenization although powder exhibited lower brightness, redness, and yellowness.     

Effects of Spray Drying Temperature and Additives on the Stability of Serine Alkaline Protease Powders

In this study, after production by recombinant Bacillus subtilis (BGSC-1A751), carrying pHV1431::subc gene in the complex medium and separation of solids from the fermentation broth, serine alkaline protease (SAP) was dried in order to investigate the stabilization during spray drying and subsequent storage. The effect of air inlet temperature of the spray dryer between T = 70 and 130°C and the effect of protective additives, glucose and maltodextrin, at 0–2% (w/v) on SAP activity during spray drying and storage stability of obtained SAP powders at 4°C for a long period (6 months) were evaluated. Increasing drying air inlet temperature generally resulted in an increase in activity loss; moreover, higher absorbance peaks observed at wave number 1061 cm^?1 of the IR spectrums when drying temperature is increased indicates the structural change in the SAP molecule. In most cases presence of additives provided higher activities both after drying and during storage period compared to no additive case. Drying the enzyme with 1% (w/v) glucose at T = 110°C resulted in the highest enzyme activity after drying and storage processes.     

Formation of a Polymer-Coated Inclusion Complex of D-Limonene and β-Cyclodextrin by Spray Drying

The polymer-coated inclusion complex powder formation of D-limonene and β-cyclodextrin obtained by spray drying was investigated with respect to the effects of various types of polymer coating agents on the powder particle size and morphology. The addition of the polymer coating agent affected the average particle size, morphology, and internal structures of the spray-dried powders. The average particle diameter of the uncoated spray-dried powders was approximately 5 µm. The powder particle size increased upon the addition of a polymer coating reagent. With the addition of 9 wt% of the polymer coating agent, an average diameter of approximately 80 µm was obtained for the spray-dried powder particles. However, further addition showed a negligible effect on the particle size. Inclusion complex crystals were observed on the surface and inside of the powder particles.     

Effect of Trehalose and Drying Process on the Survival of Encapsulated Lactobacillus casei ATCC 393

Encapsulated Lactobacillus casei ATCC 393 was prepared by extrusion technology with rice shell powder and alginate followed by drying at 4°C. Drying at 4°C was beneficial to the survival of L. casei ATCC 393 compared with freeze drying. Trehalose had a positive effect on the survival of dried L. casei ATCC 393; the live cell numbers remained over 10⁷ cfu/g after 8 weeks of storage at 4°C. Survival of L. casei ATCC 393 decreased with the increase of relative humidity (from 33 to 97%) while the immobilization technique protected cells from adverse gastric conditions (pH 1.2) by the survival ratio of 89%.     

Optimization of Cellulase Production from Isolated Cellulolytic Bacterium: Comparison between Genetic Algorithms,Simulated Annealing,and Response Surface Methodology

The present study discusses optimization of cellulase production from isolated cellulolytic bacterium. A simulated annealing (SA) algorithm is proposed for optimization of these processes to achieve the desired production goal. The approach was compared to the use of evolutionary algorithms, i.e., genetic algorithms (GAs) and response surface methodology (RSM). Ochrobactrum haematophilum was identified as the isolated bacteria. Carboxymethyl cellulose (CMC) concentration, yeast extract, pH, and incubation temperature were the significant factors screened by Plackett–Burman design and further optimized using a central composite design. The optimum values obtained were CMC concentration = 4.76% (w/v), yeast extract = 2.03% (w/v), pH = 6.3, and temperature = 44.2°C. Carboxy methyl cellulase (CMCase) activity at these values was experimentally determined to be 3.55 ± 0.16 U/ml, which was 2.8 times than the unoptimized system (1.23 U/ml). The growth-associated and non-growth-associated Leudeking–Piret constants, α and β, were respectively determined to be 0.3943 and 0.0105. The Michaelis–Menten constants, V_max and K_m, were determined to be 0.67 µmol/min and 2.42 mg CMC/ml, respectively. The variable-sized SA seems to be the best alternative, outperforming the GAs, showing a fast convergence and low variability among the several runs for optimized production cellulose recovery. The SA models are found to be capable of better predictions of cellulase production. The results of the SA-based RSM model indicate that it is much more robust and accurate in estimating the values of dependent variables when compared with the GA-based RSM models and only RSM models.     

Evaluation of physical,rheological, microbial,and organoleptic properties of meat powder produced by Refractance Window drying

Meat spoils very rapidly and its microbial load exceeds the permitted limit very soon even if it is kept in a refrigerator. The main goal of this study was to dry meat by a Refractance Window drier successfully, for the first time, and to evaluate its compositional, physical, rheological behavior, microbiological, and organoleptic properties. Meat powder produced by RW drying had good physical properties including maximum absolute density of 0.81?g?cm^?3, porosity of 0.67, rehydration ratio of 2.8, L* value of 64, and minimum a*/b* value of 0.57. Herschel–Bulkley and Bingham models could predict rheological indices of meat powder solutions with high R² rates of 0.955–0.995. Sensory evaluation indicated that although meat powder obtained from 3?mm slices was more favorable for panelists, the consistency of 2?mm meat powders was more agreeable, which could be attributed to better functional properties of more dried samples. 100°C and 2?mm treatment could decrease aerobic bacterial count from 6.1 to 3.7 log CFU/g and Enterobacteriaceae population from 3.1 log CFU/g to nil successfully. In summary, our comparison indicated that meat powder produced by Refractance Window drying technique can lead to better dried products than dried meats having been prepared with other novel techniques recently.