Microencapsulation of roselle (Hibiscus sabdariffa L.) anthocyanins: Effects of different carriers on selected physicochemical properties and antioxidant activities of spray-dried and freeze-dried powder

The physicochemical properties and the survival of Lactiplantibacillus plantarum mixed with blend of fruit juice powders dried by spray and freeze drying methods were investigated. A formula containing maltodextrin 14% and malt extract 6% as a carrier and juices of red grape 20.4%, mulberry 75.6%, and strawberry 4.0% along with the bacterium (Lpb. plantarum) with 3 × 10 9 CFU/mL were dried by spray drying and freeze drying methods, separately. The physicochemical properties including color attribute, nutritional properties of the powders such as antioxidant, and phenolic content were measured. Drying efficiency of freeze-dried was 80.48%, which was higher than the spray-dried powders (50.84%). The higher antioxidant (87.95) and total phenolic content (3032.6 mg GAE/L) was achieved by freeze drying technique; however, lower moisture content and flowability as well as higher solubility and bulk density were obtained for spray-dried powders. The survival of probiotics in freeze-dried powders was higher than the spray-dried powders which can be related to mild conditions. The study indicated that the juice powders are suitable carriers for Lpb. plantarum and constitute good alternatives to highly acidic fruit juices.

This study was designed to compare the quality characteristics of spray-dried (SD) and freeze-dried (FD) Pueraria thunbergiana extracts powder hot water extracts. Quality characteristics of the SD and FD powder including moisture content, color value, water absorption index, water solubility index, dynamic angle and antioxidant activities were evaluated. The moisture content of SD powder (1.50%) was lower than that of FD powder (2.92%). L* and b* values of SD powder was lower than of FD powder. The water absorption index was higher in FD powder (1.40) and water solubility index in SD powder (94.10%) was higher than that FD powder (90.69%). Dynamic angle of SD powder (36.46°) was higher than that of FD powder (33.30°). The DPPH radical scavenging activities of 5 mg/mL solution of SD powder and FD powder were 85.38 mg/mL, 59.38 mg/mL, respectively. And, the same trend was observed for the ABTS radical scavenging activities of the drying powder as that observed for their DPPH radical scavenging activities. There were relatively higher contents of phenolic compounds in SD powders than in FD powders. In conclusion, spray-dried Pueraria thunbergiana extracts showed the high WSI, polyphenol, DPPH and ABTS radical scavenging activities and low moisture content and dynamic angle than freeze dried powder.

The main goal of this study was to compare glass transition temperature (Tg)– aw relations, critical water activity (awc) values, particle morphology, moisture sorption behavior, total phenolic content, and stability of freeze-dried (FD) and spray-dried (SD) sour cherry powders. The Tg of the SD and FD powders decreased from 57°C to 14°C and from 47°C to 15°C, respectively, as the aw increased from 0.03 to 0.35. Higher Tg values were observed for SD powder compared to FD powder in the aw range (0.03–0.35) covered in this work. The awc was 0.29 for SD powder and 0.26 for FD powder. Scanning electron microscopy images showed that FD sour cherry powder exhibited a more porous morphology compared to SD powder. Total phenolic content of SD and FD powders was found to be similar (16.1 ± 0.3 mg GAE/g sour cherry dry matter). The results of this study suggest that physicochemical properties of spray-dried sour cherry powders are comparable to those obtained by freeze drying. Practical applications Stability of fruit-based powders is mostly determined by their Tg and awc values. Such data are scarce for sour cherry powders. The present study provides useful information on Tg and awc of sour-cherry powders produced with two drying methods. The results of this study clearly demonstrated that properties of spray-dried sour cherry powders compare favorably with those obtained by freeze drying. The findings of this study can be useful in determination of storage conditions for commercial sour cherry powders based on the awc values.

Instant coffee with stable foam is considered to be an important parameter for consumer preference and acceptability. For foam sustenance, nanoscale bubbles are more useful compared with microbubbles, due to their high specific area and high stagnation in the liquid phase (without undesirable liquid drainage). The technique that produces nanobubbles in coffee would concomitantly produce and preserve the coffee foam, the best. Spray-freeze drying (SFD) is known to be more effective for the production of instant coffee, compared with conventional spray drying (SD) and freeze drying (FD) techniques. However, its efficiency in the production of nanobubbles has not been explored. To address the issue, in the present study, SFD has been employed to produce instant coffee, and the findings have been compared with SD and FD. The coffee powder obtained with SFD produced a foam with higher stability that also comprised of nanobubbles, in contrast to SD and FD powders. The FE-SEM analysis of SFD foam showed the presence of nanobubbles in the range of 100–200 nm. When the beverage was prepared, the SFD coffee powder dissolved in water at 90 °C produced an excellent foam. The said foam structure was intact up to 2400 s (40 min), and lost only 89.5 ± 2 mm of foam height, during the experiment. Thus, apart from instant coffee, a stable foam in coffee comprising nanobubbles can also be achieved through the SFD.

This study compared the quality of organic strawberry powders, obtained by convective drying (CD), freeze drying (FD) and spray drying (SD) methods. In the study, such analyses were performed: the content of vitamin C and polyphenols by liquid chromatography method, antioxidant activity using ABTS+• radicals, microstructure using a scanning microscope, sensory quality by profile method and the determination of the physicochemical properties. The FD powders were characterised by the highest content of vitamin C and polyphenols, obtained values were close to fresh strawberries after conversion to the dry matter content. The content of these ingredients in CD and SD powders was lower by 55%–80% for vitamin C, and 80% for the polyphenols content. Strawberry flavour was most beneficial for the FD powders, while smoothness and homogeneity of appearance were equally rated for the FD and SD powders. Strawberry powders are a concentrate source of bioactive compounds and, therefore, the FD powders should especially be mainly used as a valuable component of high-value foods, especially functional foods, while CD and SD powders can be used to enrich food with vitamin C and as a valuable natural flavour and colouring component, replacing food additives.

Effect of drying methods on the physical properties and microstructures of mango (Philippine ‘Carabao’ var.) powder

Egg white protein (EWP) was phosphorylated with Sodium Tripolyphosphate (STP) at pH 4.5. Freeze drying and spray drying were used for drying purpose and the effects of these drying methods on the functional properties were investigated. The functional properties of native and modified proteins were also determined. The results demonstrated that phosphorylation of EWP markedly improved its functional properties, and that it was more effective for the food industry. The freeze-dried STP-EWP powders were superior in terms of solubility, emulsion stability, water holding capacity, oil and water absorption capacity and heat gel strength than spray-dried STP-EWP powders. The results in viscosity showed no significant differences between freeze-dried and spray dried. The spray-dried powders were better in terms of foaming ability and foam stability than freeze-dried powders. However, the spray drying required the longest time to produce. Freeze drying was found to be the best method in terms of production of modified EWP powders with superior functional properties. Keywords: freeze drying, spray drying, egg white protein, phosphorylation, functional properties DOI: 10.3965/j.ijabe.20150804.1942 Citation: Liu L L, Wang H, Ren G Y, Duan X, Li D, Yin G J. Effects of freeze-drying and spray drying processes on functional properties of phosphorylation of egg white protein. Int J Agric & Biol Eng, 2015; 8(4): 116－123.

Two plant-based emulsifiers, soybean lecithin and pea protein isolate, were studied for their emulsifying and encapsulating capacities of an antimicrobial molecule, trans-cinnamaldehyde (TC), at two different pH values, three and seven, and after drying with two different techniques, spray-drying and freeze-drying. To characterize the obtained capsules, various physicochemical tests were conducted to examine particle size, encapsulation efficiency, thermal and moisture stability, and powder morphology. The spray-dried (SD) and freeze-dried (FD) powders had an average particle size of 8.35 µm and 144.49 µm, respectively. The SD powders showed similar encapsulation efficiency (EE) for soybean lecithin and pea protein isolate with an average value of 95.69%. On the other hand, the FD powders had lower EE compared to SD powders, with an average of 58.01% for lecithin-containing powders and 83.93% for pea-protein-containing powders. However, the water content of FD powders (2.83%) was lower than that of SD powders (4.72%). The powders prepared at pH 3 showed better thermal stability. Morphological analysis showed spherical particles for SD powders and irregular shapes for FD powders. Nanoemulsions as well as dried powders showed interesting antimicrobial activities against Escherichia coli and Listeria innocua, confirming their potential use as natural preservatives in foods.

Red fruit oil is a potential coloring agent with high carotenoid content. Oil encapsulation could be done to improve its applicability to food products. This study evaluated the effect of different ratios of maltodextrin and whey protein during the encapsulation process of red fruit oil using spray and freeze drying. The powders were analyzed in terms of total carotenoid content, physicochemical properties, and stability. Spray drying resulted in powders with lower moisture content. Freeze drying resulted in powders with high carotenoid content in most samples. All powders showed low hygroscopicity and low crystallinity, but also low flowability. Spray-dried powders were spherical and wrinkled, while freeze-dried powders were irregular and rough. Sample with 1:1 ratio of maltodextrin and whey protein showed generally better properties in both spray and freeze drying. Freeze-dried powder showed better carotenoid stability than spray dried powder throughout the 4 weeks storage period.

This study was designed to compare the quality characteristics of spray-dried (SD) and freeze-dried (FD) powders prepared with hot water extracts of sea mustard (Undraia pinnatifada) and sea tangle (Laminaria longissima). The moisture content of FD seawed was lower than that of SD, and sea mustard had a higher overall moisture content than sea tangle. The alginic acid content of SD seaweed was significantly higher than that of FD seaweed for both species. There were relatively higher contents of phenolic compounds in SD powders than in FD powders. DPPH radical scavenging ability was significantly greater in SD seaweed, and also, SOD-like activity in SD powders was higher than those of FD powders. However, the nitrite scavenging activity of FD powders of sea mustard (10 mg/mL) was higher than that of SD. In conclusion, spray-dried sea mustard and sea tangle extracts exhibited higher physiological functionalities than their freeze-dried counterparts.

Whey protein concentrate (WPC) is consumed for its high protein content. The structure and biological functionality of whey proteins in WPC powders may be affected by the drying technique applied. However, the specific impact of spray drying and freeze drying on the overall protein profile of whey protein derived from sweet whey streams at scale is unknown. Herein, we examine the effects of commercial-scale freeze drying and spray drying on WPC to determine which method better preserves bioactive whey proteins, with the goal of helping the dairy industry create high-value products that meet the growing consumer demand for functional dairy products. WPCs were produced from pasteurized liquid whey using either a commercial spray dryer or freeze dryer. A variety of analytical techniques, including enzyme-linked immunosorbent assay, polyacrylamide gel electrophoresis, and bottom-up proteomics using liquid chromatography-tandem mass spectroscopy were used to identify, quantify, and compare the retention of bioactive proteins in WPC before and after spray drying and freeze drying. In addition, the extent of denaturation was studied via solubility testing, differential scanning calorimetry, and hydrophobicity assessment. There was little to no difference in the retention or denaturation of key bioactive proteins between spray-dried and freeze-dried WPC powders. There was a higher percentage of select Maillard modifications in freeze-dried and spray-dried powders than in the control. The lack of significant differences between spray drying and freeze drying identified herein indicates that freeze drying does not meaningfully improve retention of bioactive proteins compared with spray drying when performed after multiple pasteurization steps. PRACTICAL APPLICATION: This study aimed to provide insight into the impacts of spray drying versus freeze drying on whey proteins. Overall, our results indicate that for commercial dairy processing that involves multiple rounds of pasteurization, freeze drying does not meaningfully improve the retention of bioactive proteins compared with spray drying. These findings may help the food and dairy industry make informed decisions regarding the processing of its whey protein products to optimize nutritional value.

Compaction behavior of freeze-dried and spray-dried trypsin/lactose particulate systems

Effect of spray and freeze drying on physico-chemical, functional, moisture sorption and morphological characteristics of camel milk powder

Reduction of water activity in the formulations of mosquito biocontrol agent, Bacillus thuringiensis var. israelensis is very important for long term and successful storage. A protocol for spray drying of B. thuringiensis var. israelensis was developed through optimizing parameters such as inlet temperature and atomization type. A indigenous isolate of B. thuringiensis var. israelensis (VCRC B-17) was dried by freeze and spray drying methods and the moisture content and mosquito larvicidal activity of materials produced by the two methods were compared. The larvicidal activity was checked against early fourth instars Aedes aegypti larvae. Results showed that the freeze-dried powders retained the larvicidal activity fairly well. The spray-dried powder moderately lost its larvicidal activity at different inlet temperatures. Between the two types of atomization, centrifugal atomization retained more activity than the nozzle type atomization. Optimum inlet temperature for both centrifugal and nozzle atomization was 160 degrees C. Keeping the outlet temperature constant at 70 degrees C the moisture contents for the spray-dried powders through centrifugal atomization and freeze-dried powders were 10.23% and 11.80%, respectively. The LC(50) values for the spray-dried and freeze-dried powders were 17.42 and 16.18 ng/mL, respectively. Spore count of materials before drying was 3 x 10(10) cfu/mL and after spray drying through nozzle and centrifugal atomization at inlet and outlet temperature of 160 degrees C/70 degrees C were 2.6 x 10(9) and 5.0 x 10(9) cfu/mL, respectively.

Producing docosahexaenoic acid (DHA) in powder form is a great challenge as oxidation of polyunsaturated DHA takes place during drying due to higher temperature operations. One solution to this problem is to microencapsulate the DHA, which may restrict the oxidation of polyunsaturated DHA. In this study, first time spray-freeze-drying (SFD) technique is used for microencapsulating DHA and compared the results with spray-drying (SD) and freeze-drying (FD) techniques. Emulsifier of Tween-40 yielded better stability in different emulsion stability studies. A study of Fourier transform infrared spectra confirmed the presence of DHA in all the microencapsulated samples. SFD method yielded microencapsulated DHA with lower peroxidation (protected from oxidation) than FD and SD methods due to low temperature operation. However, encapsulation efficiency (oil retention) of SFD microcapsules yielded slightly lower (71 %) than the SD (about 83 %) and FD (73 %) methods. The percentage of oxidation was lower (13 %) during SFD process, whereas higher in FD (31 %) and SD (33 %) processes. Storage study indicated that SFD microencapsulated powders showed lower peroxidation than FD and SD encapsulated powders. Moreover, morphology of spray-freeze-dried samples depicted spherical shape with fine pores on the surface, while spray dried process yielded spherical shape without pores, which in turn resulted in good rehydration behavior of the SFD powdered product.