Spray Drying of Elderberry (Sambucus nigra L.) Juice to Maintain Its Phenolic Content

Spray drying was studied with Elderberry (Sambucus nigra L.) juice using a Buchi B-290 spray dryer. Different inlet temperatures ranging from 70°C to 120°C and two feed flow rates of 180 ml/hr and 300 ml/hr were considered for the experiment. The operating parameters were optimized in terms of total phenolic content retention, color, and powder recovery. The inlet temperature of 80°C with feed flow rate of 180 ml/hr gave high phenolic content retention with good color but lower recovery of the dried powder, i.e., less than 50%. To increase the recovery percentage during the drying process, the elderberry juice was spray dried with five different wall materials, i.e., soya milk powder, soya protein powder, isolated soya protein, gum acacia, and maltodextrin. Wall materials were evaluated in terms of total phenolic content retention, color of the powder, and mass recovery percentage. The gum acacia and maltodextrin gave better results and high recovery percentage, i.e., more than 70%. The best three combinations were stored under three different storage conditions in three different packagings to monitor the stability of the phenolic content and color of the powder.     

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.     

Analysis of Giant Pumpkin (Cucurbita maxima) Quality Parameters in Various Technologies of Convective Drying After Long-Term Storage

The research involved the analysis of the quality of “Justynka” variety pumpkin, dried at temperatures from 40°C to 80°C, after long-term storage. The quality of dried pumpkin was assessed based on the content of total and reducing sugar, lutein, lycopene, and β-carotene. Tests were conducted to determine the content of these substances in the samples dried with different methods; i.e., in natural and forced convection in the tunnel dryer, with the drying agent speed of 1.2 m/s, and with the two-stage method. It has been concluded that the quality of the product depends on drying time and air flow.     

益生菌在喷雾干燥过程中的活性变化与保护策略

肠道菌群对于人体健康具有重要影响。口服足量的活性益生菌,有助于缓解急慢性肠炎、治疗腹泄、改善消化,已在临床治疗中得到一定应用。在食品市场上,益生菌干粉制剂亟需一种生产成本低、制粉简便的生产方法。喷雾干燥的生产能力强、制粉快速,但干燥过程中,雾化液滴经历一个快速升温与脱水过程,对其中的益生菌带来热胁迫、脱水胁迫、氧化胁迫等多种不利因素,造成菌体活性的大量损失。而喷雾干燥塔的结构,使塔内的液滴干燥过程难以追踪,不利于研究益生菌的失活历程以及探索益生菌与载体材料间的相互作用。本文从雾化液滴在干燥塔内的干燥历程着眼,回顾了益生菌活性随液滴干燥动力学变化的趋势,讨论了益生菌在喷雾干燥中经受的亚细胞结构损伤与功能性损伤,并系统总结了目前文献中报道的提升干燥后益生菌活性的主要方法,包括提升菌体耐受性、优化喷雾干燥条件和采用合适的保护性载体,并着重阐述了载体材料与益生菌细胞间的相互作用关系以及干燥历程的重要影响。文章指出为最大程度上保存喷雾干燥粉末中益生菌的活性,应综合微生物、干燥过程与食品化学（材料学）等领域的保护策略,设计一体化统合生产方案。依据微生物-保护载体间的相互作用设计高效保护配方载体,研发统合从微生物细胞培养至粉末储藏的新型生产工艺,是实验室及工业中合理设计工业级喷雾干燥过程、大量生产高活性益生菌制剂的关键。     

Effect of maltodextrin concentration and inlet temperature during spray drying on physicochemical and antioxidant properties of amla (Emblica officinalis) juice powder

The effects of inlet temperatures of 125, 150, 175 and 200 °C and maltodextrin levels at 3, 5, 7 and 9% on the physicochemical properties, total phenolic content (TPC) and 2,2-diphenyl picryl hydrazile (DPPH) scavenging activity of spray dried amla juice powder were studied. Moisture content and hygroscopicity of powder were significantly affected by inlet temperature and maltodextrin level. However, an increase in the level of maltodextrin did not significantly affect the bulk density and water solubility index (WSI). An increase in drying temperature and maltodextrin concentration decreased the free radical scavenging activity of the powder. Morphological study revealed that at higher inlet temperatures the spray dried powder had small sized particles that were densely packed. Spray dried amla juice powder made with 7% maltodextrin and processed at 175 °C inlet temperature had less hygroscopicity, acceptable color and potent free radical scavenging activity.     

A Combination of Freeze Drying and Microwave Vacuum Drying of Duck Egg White Protein Powders

High energy consumption during freeze drying (FD) is a major concern that limits its application on common food product manufacturing. In this research, fresh duck egg white protein (FDEWP) powder and desalted duck egg white protein (DDEWP) powder were obtained by a combined two-stage tandem drying technologies (FD and microwave–vacuum drying [MVD]) in order to reduce energy consumption while maintaining good product quality. The results showed that the drying time for the FDEWP and DDEWP powders was significantly decreased by FD + MVD compared to those obtained by the FD-only process. The FDEWP powders dried by FD + MVD had a better color (higher L* and lower b*), lower apparent density, and lower foaming stability but higher emulsifying index than those dried by FD only. The DDEWP powder dried by FD + MVD had a product quality similar to that of FDEWP powder, suggesting that the DDEWP powder could be widely used as a food ingredient.     

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.     

Spray Drying and Process Optimization of Unclarified Pomegranate (Punica granatum) Juice

In this study, production of pomegranate juice powder using a spray dryer was investigated. To prevent stickiness, maltodextrin dextrose equivalent 6 (DE6) was used as a drying agent. While feed flow rate, feed temperature, and air flow rate were kept constant, air inlet temperature (110–140°C), percentage maltodextrin (MD; maltodextrin dry solids/100 g feed mixture dry solids; 39.08–64.12%), and feed mixture concentration (19.61–44.11 °Brix) were chosen as the independent variables. Product properties investigated included moisture content, hygroscopicity, anthocyanin content, color change, solubility, bulk density, total phenolics content, antioxidant capacity, and sensory properties. The products were produced with high yield (86%) and high antioxidant activity (77%). MD and drying temperature were found to be the most important variables in production of pomegranate juice powders. Because total color change (ΔE), bulk density, antioxidant capacity, and powder yield were affected strongly by the independent variables, these parameters were used in optimization of the process. The optimum temperature, feed mixture concentration, and percentage maltodextrin were 100°C, 30.8 °Brix, and 53.5% MD, respectively. This study revealed that by applying these optimal conditions, pomegranate juice powder with a 55% dry solids yield, 9.78 total color change, 0.35 g/mL bulk density, and 57.8% antioxidant capacity were produced.     

Scanning Electron Microscopic Study of Microstructure of Gala Apples During Hot Air Drying

Microscopic changes that occur in plant food materials during drying significantly influence the macroscopic properties and quality factors of the dried food materials. It is critical to study the microstructure to understand the underlying cellular mechanisms to improve the performance of food drying techniques. However, there is limited research on such microstructural changes of plant food material during drying. In this work, Gala apple parenchyma tissue samples were studied using a scanning electron microscope for gradual microstructural changes as affected by temperature, time, and moisture content during hot air drying at two drying temperatures: 57 and 70°C. For fresh samples, the average cellular parameter values were as follows: cell area, 20,000 µm²; ferret diameter, 160 µm; perimeter, 600 µm; roundness, 0.76; elongation, 1.45; and compactness, 0.84. During drying, a higher degree of cell shrinkage was observed with cell wall warping and an increase in intercellular space. However, no significant cell wall breakage was observed. The overall reductions in cell area, ferret diameter, and perimeter were about 60, 40, and 30%. The cell roundness and elongation showed overall increments of about 5% and the compactness remained unchanged. Throughout the drying cycle, cellular deformations were mainly influenced by the moisture content. During the initial and intermediate stages of drying, cellular deformations were also positively influenced by the drying temperature and the effect was reversed at the final stages of drying, which provides clues regarding case hardening of the material.     

Foam Mat Drying of Alphonso Mango Pulp

The foam mat drying of Alphonso mango pulp using various food foaming agents, namely soy protein (0.25, 0.5, 1.0, and 1.5%) with methyl cellulose (0.5%), glycerol mono stearate (0.5, 1.0, 2.0 and 3.0%), and egg albumen (2.5, 5.0, 10 and 15%) with methyl cellulose (0.5%), was studied. Drying was carried out in a batch type thin layer dryer at four drying temperatures (60, 65, 70, and 75°C) on 1-, 2-, or 3-mm thickness foamed samples. The optimum concentrations of each foaming agent were determined to be 1% soy protein, 2% glycerol mono stearate, and 10% egg albumen. All were obtained after 25 min whipping time. The drying time was lower for foamed mango pulps as compared to non-foamed pulp at all drying temperatures. Biochemical analysis showed that the foam mat dried powder at 60°C retained a significantly higher (P < 0.05) content of biochemical compounds than at higher temperatures. The treatment of mango pulp with 10% egg albumen and 0.5% methyl cellulose and drying at 60°C (1-mm foam thickness), retained the highest nutritional quality characteristics than the other treatments.     

Influence of Drying Techniques on the Characteristics of Chitosan and the Quality of Biopolymer Films

In this work, spouted bed and tray-drying techniques were employed at different drying air temperatures to produce dried chitosan, and the chitosan powder was used to produce biofilms. The products obtained from each drying technique were compared in relation to quality aspects (molecular weight, lightness, and hue angle). The results found for chitosan in spouted bed drying (90°C) showed lower alteration and best quality aspects in relation to the chitosan powder. However, in tray drying under the best condition (60°C) the chitosan molecular weight increased about 50% in relation to the initial value and browning was observed. The biofilms produced from chitosan dried in the spouted bed showed the best mechanical properties (tensile strength of 42 MPa and elongation of 29%) and lower water vapor permeability (3.95 g mm m^?2 kPa^?1 day^?1).     

DRYING CHARACTERISTICS OF RED CHILLI

ABSTRACT

Red chilli is widely consumed as a food additive throughout the world. It is blanched/treated to minimize quality loss during processing. This paper reports on various pre-treatments applied before drying and their influence on drying kinetics as well as product quality. Inactivation of peroxidase enzyme was achieved by blanching chillies at 90°C for 3 min in hot water. The physical appearance of the dried product was found to be the best when the blanched samples were soaked in gum acacia solution (0.2% m/v) for 15 min at room temperature. The pre-treated chillies were dried in a tray dryer at selected temperatures (55, 60, 65 and 70°C). Results indicated that drying took place in the falling rate period; the drying kinetics were adequately described by the Page's model. The activation energy for drying was determined to be 41.95 and 41.06 kJ/mol respectively, for blanched and gum-treated chillies. Total pigment content decreased while non-enzymatic browning increased with increase in drying air temperature.     

Drying Kinetics and Bioactivity of Beetroot Slices Pretreated in Concentrated Chokeberry Juice and Dried with Vacuum Microwaves

Beetroot slices 18 mm in diameter and with a thickness of 9.6, 6.3, 3.35, or 2.6 mm were pretreated in 40°Bx chokeberry juice at a temperature of 50°C for 2 h and then dried by a vacuum-microwave (VM) method at different microwave power levels, such as 120, 240, 360, 480, and 480/120 W. The drying kinetics were described by a fitted model that incorporated contributions from the surface area of the samples, microwave power, and VM processing time. As the microwave power during VM drying increased, the bioactive potential decreased for untreated samples and increased for pretreated samples. Increasing the samples' specific surface area resulted in shorter drying time, lower temperature of the material during drying, and enhanced quality of the dried product. For osmotically pretreated beetroot slices with a specific surface area of 827 ± 18 m²m^?3, a final VM drying step at 240 W is recommended to produce high quality vegetable snacks.     

Effect of Fluidized Bed Drying Temperature on Various Quality Attributes of Paddy

Abstract

As reported by many researchers, it was found that fluidized bed paddy drying using high drying air temperatures of over 100°C affected the head rice yield and whiteness of dried rice. However, only a few studies on fluidized bed paddy drying with drying air temperatures below 100°C were so far reported. The main objective of this work was therefore to study the effect of fluidized bed drying air temperature on various quality parameters of Suphanburi 1 and Pathumthani 1 Indica rice. Paddy was dried from the initial moisture contents of 25.0, 28.8, and 32.5% dry basis to 22.5 ± 1.2% dry basis using inlet drying air temperatures between 40 and 150°C at 10°C/step. After fluidized bed drying, paddy was tempered and followed by ambient air aeration until its final moisture content was reduced to 16.3 ± 0.5% dry basis. The results showed that the head rice yield of Suphanburi 1 was significantly related to the inlet drying temperature and initial moisture content whilst there was no significant relationship between the head rice yield, drying temperature and initial moisture content for Pathumthani 1. The whiteness of the two rice varieties was slightly decreased with increase in drying air temperature and initial moisture content. It was also found that the hardness of both cooked rice varieties exhibited insignificant difference (p < 0.05) comparing to rewetted rice, which was gently dried by ambient air aeration in thin layer. The thermal analysis by DSC also showed that partial gelatinization occurred during drying at higher temperatures. Using inlet drying air temperatures in the range of 40–150°C therefore did not affected the quality of cooked rice and paddy. The milling quality of paddy was also well maintained.     

The Role of Processing Conditions on the Color and Antioxidant Retention of Jet Tube Fluidized Bed–Dried Blueberries

Jet tube fluidized bed drying was investigated as a means of rapidly generating shelf-stable and high-quality sweetened and nonsweetened blueberries. Sugar-infused and noninfused scarified Rabbiteye blueberries (Vaccinium ashei ‘Brightwell’) were dried at 99, 107, and 116°C. Prior scarification of the blueberry surface aided in decreasing the drying time. Increased lightness (L*) values were most notable at higher drying temperatures for sugar-infused blueberries, suggesting loss of pigments. Total monomeric anthocyanins level, initially 7.65 mg cyanidin-3-O-glucoside equivalents (C3G eq)/g extract, decreased as drying temperature increased and ranged between 4.07 down to 1.51 mg C3G eq/g extract for dried blueberries. The total phenolics content increased with drying for noninfused blueberries, with highest levels of 31.6 mg gallic acid equivalents (GAE)/g extract for samples dried at 107°C. With the exception of sugar-infused berries dried at 107 and 116°C, the dried blueberries maintained or demonstrated slightly increased hydrophilic oxygen radical absorbance capacity (H-ORAC_FL) values, indicating that their antioxidant capacity was retained upon drying. Blueberries dried at 107°C possessed the greatest preference scores and best retention of blueberry flavor and required a relatively short drying time.     

Physicochemical and nutraceutical properties of barley grass powder microencapsulated by spray drying

ABSTRACT

Barley grass (Triticum aestivum L.) is popular, commonly known as a nutritional supplement in China. To obtain the highest chlorophyll and flavonoid content as well as other physicochemical characteristics, spray drying from barley grass juice was carried out for two different maltodextrin concentrations (10 and 20%, dried basis) and four different inlet air temperatures (140, 150, 160, and 170°C). After drying, color, water activity, odor, taste, density, particle size, glass transition temperature, and chlorophyll and flavonoid contents of the dried product were measured. Highest contents of flavonoid (5.66?mg/kg) and chlorophyll (7.29?mg/kg) were obtained under 150°C inlet air temperature, 10% maltodextrin concentration, at a feed flow rate of 1.8?L/h for the drying. Corresponding particle size was 19.58–13.33?µm. The glass transition temperature (T_g) increased with the increasing of maltodextrin concentration; and two max T_g of powder obtained from 10 and 20% maltodextrin concentration were 74.4 and 77.4°C, respectively. Retention of taste and flavor were highest with 20% maltodextrin. High inlet air temperature was contributed to the large discrepancy of odor and taste substances. The best color (lightness L*?=?64.44 and greenness b*?=??11.53) was obtained at 150°C inlet air temperature and 10% maltodextrin concentration. Both maltodextrin concentrations resulted in poor flowability of the dried product (C_I?≤?32.51).     

Microwave,Vacuum, and Air Drying Characteristics of Collard Leaves

Collard leaves (Brassica oleracea L. var. acephala) with an initial moisture content of 6.65 on percentage dry basis (%db) were dried by three different drying methods: microwave, air, and vacuum. Samples of fresh leaves, 25 g each, were dried until their moisture was down to 0.1 on a dry basis. The following drying levels were used in each of the drying processes: 350, 500, 650, 750, 850, and 1000 W for microwave drying; 50, 75, 100, 125, 150, and 175°C for air drying; and 0.4, 50, and 100 mmHg at 50 and 75°C for vacuum drying, respectively. Drying times ranged between 2.5 to 7.5 min, 8 to 210 min, and 35 to 195 min for microwave, air, and vacuum drying, respectively. The data obtained compared well with a thin-layer drying model. Microwave drying at 750 W provided optimal results with respect to drying time, color, and ascorbic acid content (vitamin C).     

Sorption Properties of Vacuum-Dried Strawberries

This work demonstrates the influence of changes in parameters of vacuum drying (temperature and pressure) on the sorption properties of dried strawberries. Fruits were dried at 50 and 70°C under pressures of 4 and 16 kPa. Vacuum drying was also conducted during the first 4 h at 70°C and then the temperature was decreased to 50°C at a pressure of 4 kPa. The other combination included increasing the pressure after the first 4 h from 4 to 16 kPa at a drying temperature of 70°C. Sorption isotherms were determined in the dried strawberries. It was shown that with increasing drying temperatures, there was a notable deterioration in the capacity for absorbing water vapor by the vacuum-dried fruit. On the other hand, the pressure at which vacuum drying proceeded did not significantly affect water vapor absorption. Changing the parameters of vacuum drying—that is, temperature in the range of 50–70°C and pressure in the range of 4–16 kPa—affected the shape and structure of the resultant dried strawberries. The combination of vacuum drying with convective drying also influenced the shape and structure of the dried fruit.     

Convective Drying Kinetics of Red Chillies

The drying kinetics of four varieties of chillies (Pb-Lal, Pb-Guchhedar, Pb-Surkh, and CH-1) was studied. The chillies (pricked and unpricked) were pretreated in the dip sol solution. The treated chillies were dried in an automatic weighing experimental dryer at selected temperatures (45°, 50°, 55°, 60°, and 65°C). The results indicated that drying took place in the falling rate period. Out of three models considered, Page's model was found to be the most suitable for describing the drying behavior of chillies. The dependence of drying constant on temperature was analyzed using an Arrhenius equation. The variety Pb-Lal has the maximum value of activation energy (42.59 kJ/mol), which is also reflected in the reduced drying time for this variety. The results of quality studies of dried chillies in terms of capsaicin content and coloring matter indicated that the Pb-Lal variety had acceptable capsaicin content of 532.08 µg and coloring matter of 73.8 ASTA.     

Evaluating a Solar Dryer for In-Shell Drying of Split Pistachio Nuts

Abstract

A thin-layer forced air solar dryer was designed to study the feasibility of drying pistachio nuts. The dryer was tested during the 2001 and 2002 drying seasons. The maximum temperature in the solar collector reached 56°C, which was 20°C above the ambient temperature. The required drying time was 36 h. During the first day of drying (0800 to 1700 h) the moisture content dropped to about 21% (wb). The final moisture content of the dried nuts was 6% wb, which was 1% below the recommended storage moisture. The drying constant of the pistachio nuts during solar drying was determined using two mathematical models, a one-term series solution of Fick's diffusion equation and an exponential decaying model. There was no significant difference between the two models (α = 0.05). In general, the quality of solar dried nuts was better than the conventional heated air due to slower drying rates.