共查询到20条相似文献,搜索用时 31 毫秒
1.
Tatiana Lopes Fialho Evandro Martins Arlan Caldas Pereira Silveira Carolina Rodrigues de Jesus Silva Pierre Schuck 《Drying Technology》2018,36(8):922-931
Industrial production of lactose hydrolyzed milk powder (LHMP) remains challenging. Due to the presence of the monosaccharides glucose and galactose, lactose-free powders tend to suffer stickiness, caking, and browning during drying and storage. We sought to find ideal conditions spray dryer inlet air temperature (θair,in) and concentrated milk flow rate (mCM) for LHMP production. We tested θair,in settings of 115–160°C and mCM of 0.3–1.5?kg?·?h?1, and also applied mass and energetic balances. LHMP generally exhibited higher mass and energetic losses than the control (milk powder containing lactose), as a consequence of the relatively low dryability of LHMP. For a lab scale spray dryer, the ideal conditions settings for LHMP production were θair,in?=?145?±?2°C and mCM?=?1.0?kg?·?h?1, taking into account the mass yield and energetic cost (kJ?·?kg?1 of powder) of the process. These ideal conditions are a potential tool for the industrial development of lactose-free dairy powders. 相似文献
2.
A drying technique using a combination of a contact ultrasound apparatus and a hot air dryer is developed to investigate the strengthening effect of contact ultrasound on hot air drying. The effects of drying parameters such as ultrasound power and drying temperature on drying characteristics, effective moisture diffusivity (Deff), microstructure, glass transition temperature (Tg), rehydration ratio, and color difference are discussed. The results show that the application of contact ultrasound causes a significant acceleration of internal mass transfer, and higher ultrasound power applied leads to faster drying rate. The effect of ultrasound power on drying rate decreases along with the reduction of moisture content during drying process. The increase in drying temperature significantly reduces drying time but has a little negative influence on the strengthening effect of ultrasound. Deff values range from 1.0578?×?10?10 to 5.4713?×?10?10?m2/s in contact ultrasound-assisted hot air drying of purple-fleshed sweet potato and increase significantly with an increase in drying temperature as well as ultrasound power. The microstructure of purple-fleshed sweet potato is greatly different at different ultrasound powers during contact ultrasound-assisted hot air drying and shows more microchannels and dilated intercellular spaces in the cross-section of purple-fleshed sweet potato micrographs at higher ultrasound power. Contact ultrasound application during hot air drying could improve the mobility of water and consequently reduce glass transition temperature. Lower color difference and higher rehydration ratio could be achieved as drying temperature decreases and ultrasound power increases. The increase in contact ultrasound power could reduce energy consumption of drying process up to 34.60%. Therefore, contact ultrasound assistance is a promising method to enhance hot air drying process. 相似文献
3.
Long Xie Zhi-An Zheng A. S. Mujumdar Xiao-Ming Fang Jun Wang Qian Zhang 《Drying Technology》2018,36(12):1501-1514
The effects of drying temperature (50, 53, 56, 59, 62, and 65°C) and pulsed vacuum ratio defined as the vacuum pressure duration versus atmosphere pressure duration (3:3, 6:6, 9:2, 12:5, 15:1, 18:4?min/min) on pulsed vacuum drying (PVD) characteristics and quality attributes of wolfberry in terms of polysaccharide content, color parameters (L*, a*, b*, ΔE, and C), rehydration ratio and microstructure were investigated. Results revealed that appropriate PVD can reduce drying time by 73.2% compared to hot air drying at the same drying temperature. The moisture effective diffusivity (Deff) ranged from 5.23?×?10?10 to 9.73?×?10?10?m2/s, calculated using the Weibull distribution model. The polysaccharide content, L* (lightness), a* (redness/greenness) of the PVD products were higher than those of the hot air-dried samples at the same drying temperature. The total color difference (ΔE) and color intensity (C) of PVD samples were close to those of the fresh ones. The retention rate of total polysaccharide content of PVD samples was about 49–77%, which was significantly higher than 30% of the hot air-dried samples. The surface of PVD wolfberry was highly porous, which may enhance moisture transfer during drying as well as rehydration processes. The results of current work indicate that PVD is a promising technology for wolfberry process, for the reason that PVD can reduce drying time significantly as well as enhance the quality attributes in terms of the total polysaccharide content, color parameters and rehydration ratio. 相似文献
4.
Yunhong Liu Changying Sun Yuqing Lei Huichun Yu Huihan Xi Xu Duan 《Drying Technology》2019,37(6):745-758
In order to investigate the feasibility and the enhancing effect of contact ultrasound application during far-infrared radiation (FIR) drying, a contact ultrasound strengthened FIR (CUFIR) drying equipment was fabricated and used, and CUFIR drying experiments on pear slices were carried out to explore the synergetic effects of ultrasound power and FIR heating on drying characteristics, microstructure, and quality of dried pear products. The results show that the application of contact ultrasound could be obviously helpful to accelerate internal mass transfer in pear slices and improve the drying rate of FIR drying, and higher ultrasound power could lead to stronger strengthening effect. The enforcing effect of ultrasound increased at higher FIR power, and weakened with the reduction of moisture content during CUFIR drying. The Deff values ranged from 4.76?×?10?10?m2/s to 13.94?×?10?10?m2/s in this study and the increase of both FIR power and ultrasound power had significant and positive influence on the increasing of Deff values. With scanning electrical microscope (SEM), it was observed that the improvement of ultrasound power could enlarge the size of microcapillaries and even generate new micropores and microchannels on the ultrasound-treated surface and in the organism structure of pear slices. The increase of ultrasound power could improve total phenolic content (TPC) and total flavonoids content (TFC) of pear slices at FIR powers of 100 and 220?W. Yet, the application of contact ultrasound with ultrasound power of 60?W had negative influence on TPC and TFC at FIR power of 340?W. Although the ascorbic acid content (AAC) reduced as FIR powers increased during FIR drying without contact ultrasound assistance, the increase of ultrasound power could improve AAC at all FIR powers. The CUFIR drying at ultrasound power of 60?W and FIR power of 220?W achieved the lowest energy consumption. Therefore, the application of FIR drying combined with contact ultrasound is a promising method to improve drying rate as well as protect product quality. 相似文献
5.
Long Xie A. S. Mujumdar Qian Zhang Jun Wang Shuxiang Liu Lizheng Deng 《Drying Technology》2017,35(11):1312-1326
ABSTRACTThe drying kinetics and quality attributes of wolfberry were investigated under pulsed vacuum drying based on two different heating ways of far-infrared radiation (PVD-FIR) and electronic panel contact (PVD-EPC) heating. They were operated at different drying values of heating panel temperatures (60, 65, and 70°C) with 15 and 2?min as the constant vacuum pressure and atmospheric pressure duration, respectively. Drying time for wolfberry dried by PVD-FIR was lower by 17–19% compared with that by PVD-EPC at the same drying temperature. The effective moisture diffusivity (Deff) determined by Weibull distribution model ranged from 3.72?×?10?10 to 6.59?×?10?10?m2/s and 3.34?×?10?10 to 6.88?×?10?10?m2/s for PVD-FIR and PVD-EPC, respectively. The drying activation energy was 54.30 and 68.59?kJ/mol for the samples dried by PVD-FIR and PVD-EPC, respectively. The color parameters L*, a*, and b* of wolfberry dried by PVD-FIR were higher than those dried by PVD-EPC. The product dried by PVD-FIR contained more vivid luster compared to that dried by PVD-EPC. The contents of aldehydes, esters, phenols, and the heterocyclic compound in PVD-FIR sample were higher than those in PVD-EPC samples. Additionally, the alcohols, ketones, and acid contents in PVD-FIR sample were lower than those in PVD-EPC sample. In summary, PVD-FIR is more suitable for wolfberry drying as it enhances drying rate and product’s quality compared with PVD-EPC. 相似文献
6.
Alfredo Domínguez-Niño Denis Cantú-Lozano Juan A. Ragazzo-Sanchez Isaac Andrade-González 《Drying Technology》2018,36(5):597-608
The influence of spray drying conditions on the energy required, production cost, and physicochemical characteristics of cheese whey was researched. The factors investigated were the inlet air temperature (180–220°C), outlet air temperature (80–100°C), and silica and maltodextrin (DE-10) as additives at 2 and 5% (w/w), respectively. Analysis of variance revealed that the inlet and outlet air temperatures, and the addition of additives had significant effects (p?0.10) on the response variables. The best drying conditions were a Tinlet of 180°C, Toutlet of 80°C, and the addition of 5% additive material. Under these conditions, 0.2165?kg/h of dried product was obtained, with a moisture content of 2.08% and water activity of 0.125, and the product cost was $17.06?kg with an energy consumption of 2.0490?kW?·?h/kg of dry product. 相似文献
7.
Scientific literature of agromaterial drying present contradictory conclusions in terms of the kinetic effect of airflow velocity. Some authors confirmed that it does not trigger any modification of drying, while some articles tried to establish empirical models of the effective diffusivity Deff versus the airflow velocity, what is fundamentally erroneous. By analyzing internal and external transfer phenomena, this research aimed at recognizing that once air velocity is higher than a critical airflow velocity (CAV), the internal transfers become the limiting phenomenon. CAV depends on the effective diffusivity and the product size. It was calculated in the cases of two studied raw materials (apple and carrot), differently textured by instant controlled pressure drop (DIC). Values of CAV greatly depend on diffusivity of water within the matrix. At temperature T?=?40°C, they were 1?m/s for untreated carrot and 2.1?m/s for DIC-textured carrot, whose Deff values were 1.31 and about 3?×?10?10?m2/s, respectively. Also, at temperature T?=?40°C, they were 2.1?m/s for untreated apple and 3?m/s for DIC-textured apple, whose Deff were 1.4 and about 10.4?×?10?10?m2/s, respectively. 相似文献
8.
Li-Zhen Deng Xu-Hai Yang A. S. Mujumdar Jin-Hong Zhao Dong Wang 《Drying Technology》2018,36(8):893-907
Results of an experimental study are presented and discussed for pulsed vacuum drying (PVD), infrared-assisted hot air-drying (IR-HAD), and hot air-drying (HAD) on drying kinetics, physicochemical properties (surface color, nonenzyme browning index, red pigments, rehydration ratio, water holding capacity, and ascorbic acid), antioxidant capacity (ferric reducing antioxidant power and 2,2-diphenyl-1-picrylhydrazyl radical scavenging capacity), and microstructure of red pepper. As expected, the drying time decreased with an increase in drying air temperature, IR-HAD needed the shortest drying time, followed by HAD and PVD. The effective moisture diffusivity (Deff) of red pepper under PVD, HAD, and IR-HAD was computed to be in the range 1.33–5.83?×?10?10, 1.38–6.87?×?10?10, and 1.75–8.97?×?10?10 m2/s, respectively. PVD provided superior physicochemical properties of dried red pepper compared to samples dried by HAD and IR-HAD. In detail, PVD yielded higher rehydration ratio, water holding capacity, red pigment and ascorbic acid content, brighter color, lower nonenzyme browning index, and comparable antioxidant capacity compared to samples dried by HAD and IR-HAD at the same drying temperature. Furthermore, PVD promoted the formation of a more porous structure, while HAD and IR-HAD yielded less porous structure. The current findings indicate that PVD drying has the potential to produce high-quality dried red pepper on commercial scale. 相似文献
9.
Valeria S. Eim José V. García-Pérez Carmen Rosselló Antoni Femenia 《Drying Technology》2013,31(2):146-153
The formulation of a dry fermented sausage has been modified by the addition of carrot dietary fiber (CDF; 3, 6, 9, and 12% [w/w]), and the influence of this change on the drying curves and food microstructure has been studied. The CDF content influenced the initial moisture content as well as the drying rate. A diffusion model taking into account the change in the product formulation has been proposed to simulate the drying curves. A constant mass transfer coefficient of 2.53 × 10?8 m/s was obtained and the effective water diffusivity varied exponentially with the CDF content from 0.99 × 10?11 m2/s (0% CDF) to 2.08 × 10?11 m2/s (12% CDF). The simulation of the drying curves was satisfactory (mean relative error of 0.5 ± 0.1%). No differences in the microstructure related to the proteolytic process were found among samples with different CDF contents. 相似文献
10.
In the current study, evolution of thermophysical properties of red chilli dried in a mixed mode solar dryer that integrates sodium sulfate decahydrate (Na2SO4?·?10H2O) and sodium chloride (NaCl) as thermal storage were presented. Solar drying with Na2SO4?·?10H2O reduced the drying time by 26.7 and 39%, compared to the drying time with or without NaCl. Dimensional shrinkage was gradual with a nonlinear exponential shape for the whole drying conditions. The evolution of the bulk and particle densities decreased while the porosity of the seed increased with time. The coefficient of heat and mass transfer varied from 0.0036???0.035?W/m2?K to 6.09?×?10?9???6.2?×?10?8?m/s, respectively. The thermal conductivity, specific heat capacity, and thermal diffusivity ranged from 0.0568 to 0.1093?W/m?K, 1,072 to 2218.7?J/kg?K, and 4.7?×?10?5 to 5.13?×?10?5?m2/s, respectively. 相似文献
11.
AbstractThis work evaluated the effect of ultrasonic pretreatment on the production of dehydrated apples (Malus domestica L. var Granny Smith) in a fluidized bed dryer. Cube-shaped apple samples were subjected to ultrasound in an ultrasonic bath and dried in a fluidized bed drier. The experimental design evaluated the effect of ultrasound pretreatment time (0 to 30?min) on the soluble solids loss during pretreatment and on the drying time. The ultrasonic pretreatment was carried out in a bath ultrasound operating at 25?kHz and outputting 55?W/m3 of power density. Distilled water was applied in the pretreatment to produce low-calorie apple cubes. Fluidized bed drying was carried out at 30, 40, and 50?°C. Fick’s law was used to model the drying process and to determine the apparent water diffusivity. The soluble solid loss ranged between 8.7 and 21.2% during the pretreatment, and the apparent water diffusivity during air drying ranged from 1.09?×?10?6 to 2.81?×?10?6 m2/min. Ultrasound pretreatment increased the apparent water diffusivity up to 58%. Apple cubes subjected to 20?min of ultrasound pretreatment and dried at 50?°C presented the highest apparent water diffusivity and dried to achieve a water activity of 0.4 in 100?min. 相似文献
12.
ABSTRACTThe work is for the purpose of studying the influence of drying temperature and ultrasound on drying kinetics, antioxidant enzymes, and germination performance of pea seeds. The drying experiments were performed at air temperature of 30, 35, and 40°C without ultrasound and with three ultrasonic levels of 28?kHz?+?60?W, 28?kHz?+?100?W, and 40?kHz?+?60?W. The antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) and the toxic substances such as malondialdehyde (MDA) of the dried seeds were determined, and germination percentage (GP), germination index (GI), and mean germination time (MGT) were measured. The result showed that high temperature and ultrasound application had significant (P?<?0.05) enhancing of pea seed drying kinetics, which shortened the drying time and improved the diffusion coefficient from 3.528?×?10?11 to 5.668?×?10?11?m2/s. Page model can well describe the drying curves under different experiment conditions. Ultrasound application significantly (P?<?0.05) improved the activities of SOD, POD, and CAT and reduced the MDA content. In addition, high ultrasonic power contributed to the increase in GP and GI and the reduction of MGT of seeds. 相似文献
13.
Yingting Zhao Yimei Zheng Zhiyu Li Yajun Jiang Weijing Zhuang Baodong Zheng 《Drying Technology》2020,38(4):534-544
AbstractUltrasonic pretreatments were applied to lotus seeds at acoustic energy densities of 0.29, 0.40, and 0.51?W mL?1 for 10?min. After pretreatments, lotus seeds were subjected to microwave vacuum drying (MVD). Parameters of glass transition temperature (Tg), gelatinization temperature (Tp), water state, color kinetics, and free amino acid content of microwave vacuum dried lotus seeds were determined. With increasing acoustic energy density, MVD elevated the Tg values appreciably by decreasing the content of cytoplasmic bulk water in lotus seeds tissues. The Tp had a positive relationship with the relaxation times of cytoplasmic bulk water (T22), while Tg had a negative relationship with T22. Color kinetics were analyzed by the divisional method during MVD due to different browning reactions, which failed to appear with ultrasonic pretreatment. Free amino acid content ranged from 517.65 to 666.13?mg/100?g dry weight at 0.51?W mL?1. 相似文献
14.
Jiazhen Zhou Ruina Zhang Xing Wang Shanping Chen Anran Luo Dongjie Niu 《Drying Technology》2017,35(10):1276-1287
Drying sewage sludge is a highly energy-extensive process. For this reason, this work seeks to identify a reagent that can enhance the effectiveness of the drying process. In this study, drying experiments of sewage sludge were conducted at drying temperatures ranging from 100 to 160°C. NaHCO3 was selected as the drying reagent, which was added to the sludge before drying. The thin-layer drying characteristics of the sludge and sludge/NaHCO3 mixtures were later investigated and compared. Various mathematical models were used to simulate the sludge drying curves. It was found that adding 2 and 6% (wet basis) of NaHCO3 to the sludge was effective in improving the moisture diffusion during the drying process, whereas the drying rate of the sludge/NaHCO3 mixtures decreased when the addition of NaHCO3 was further increased to 10% (wet basis). When the addition ratio was 2%, the increase in the maximum drying rate was the largest. With coefficients of determination (R2) over 0.9999, the modified Midilli model proposed in this study was observed to be the most suitable model to describe thin-layer drying of sludge relative to the other models examined in terms of R2, reduced χ2, root mean square error, and residual sum of squares. The values of the diffusion coefficients at each temperature were obtained using Fick’s second law of diffusion, which varied from 3.700?×?10?9 to 1.085?×?10?8?m2/s over the temperature range (i.e., 100–160°C). The activation energy of moisture diffusion was determined to be 27.57?kJ/mol. Scanning electron microscope images of the dried sludge and sludge/NaHCO3 mixtures indicated that the porosity of the sludge after drying increased with an increase in the NaHCO3 addition ratio. Overall, the results suggested that NaHCO3 is a suitable reagent to improve the drying efficiency of the sludge. 相似文献
15.
The commercially available paprika at 16.25% (db) moisture was quickly finish-dried using microwaves at higher power density (5–25?W?g?1). The moisture diffusivity was estimated using Fick’s second law of diffusion and the generalized kinetic model was used to estimate the color degradation rates. The moisture diffusivity and color degradation showed a close correlation with the difference between the average product temperature (T) achieved due to microwave heating, and average glass transition temperature (Tg) of paprika. Acceleration in moisture diffusion and color degradation was observed with the rise in the difference between the T and Tg. Further, the color degradation rate showed correlation with monolayer moisture content, average moisture content, T, and Tg of paprika during finish drying. The constants of the Gordon and Taylor model showed the less plasticization effect of water. Also, Tg showed a good correlation between water activity and moisture content. The activation energies for moisture diffusion and color degradation were found to be 92.53 and 11.03?kJ mol?1, respectively. The microstructural analysis of finish-dried paprika showed the expanded and newly formed intercellular spaces. The developed correlations can be used to simulate heat and mass transfer operations such as drying and sterilization. 相似文献
16.
The influence of pulsed electric field (PEF) and subsequent centrifugal osmotic dehydration (OD) on the convective drying behavior of carrot is investigated. The PEF was carried out at an intensity of E = 0.60 kV/cm and a treatment duration of t PEF = 50 ms. The following centrifugal OD was performed in a sucrose solution of 65% (w/w) at 40°C for 0, 1, 2, or 4 h under 2400 × g. The drying was performed after the centrifugal OD for temperatures 40–60°C and at constant air rate (6 m3/h). With the increase of OD duration the air drying time is reduced spectacularly. The dimensionless moisture ratio Xr = 0.1 is reached for PEF-untreated carrots after 370 min of air drying at 60°C in absence of centrifugal OD against 90 min of air drying after the 240 min of centrifugal OD. The PEF treatment reduces additionally the air drying time. The total time of dehydration operations can be shortened when OD time is optimized. For instance, the minimal time required to dehydrate untreated carrots until Xr = 0.1 is 260 min (120 min of OD at 40°C and 140 min of drying at 60°C). It is reduced to 230 min with PEF-treated carrots. The moisture effective diffusivity D eff is calculated for the convective air drying based on Fick's law. The centrifugal OD pretreatment increases drastically the value of D eff . For instance, 4 h of centrifugal OD permitted increasing the value of D eff from 0.93 · 10?9 to 3.85 · 10?9 m2/s for untreated carrots and from 1.17 · 10?9 to 5.10 · 10?9 m2/s for PEF-treated carrots. 相似文献
17.
Effect of pretreatment on water migration and volatile components of heat pump dried tilapia fillets
AbstractIn this study, ultrasonic assisted osmotic pretreatment and pulsed vacuum assisted osmotic pretreatment were applied to investigate their effects on water migration and volatile components of heat pump dried Tilapia fillets. To achieve that, some effective parameters including sample drying rate, water diffusivity, microstructure, water morphology, water distribution, and volatile components were compared and analyzed with some advanced measurement devices. The water diffusivity, water distribution characteristics, and composition of volatile components were obtained after different pretreatment methods. As the drying process progresses, the sample moisture content decreases. Meanwhile, the high-degree-of-freedom water migrates to the low-degree-of-freedom water and the water-solid bond strength increases. Subsequently, the effective water diffusion coefficients of control group (without pretreatment samples), ultrasonic assisted osmosis pretreatment group and pulsed vacuum assisted osmosis pretreatment group were measured as 4.304?×?10?7m2/s, 6.109?×?10?7m2/s, and 5.003?×?10?7m2/s, respectively. In addition, the control group, ultrasonic assisted osmosis group, and pulse vacuum assisted osmosis group contained 52, 59, and 41 volatile compounds, respectively. Compared to the results from the control group, the water diffusion coefficients of ultrasonic osmotic pretreatment and pulse vacuum osmotic pretreatment increased by 41.94% and 16.24%, respectively. From the point of view of increasing drying rate, the ultrasonic penetration pretreatment provided better improvement, which was exactly consistent with the results of microstructure. On the other hand, the ultrasonic assisted osmotic pretreatment group had more types of volatile compounds, which could stimulate more flavored substances to be released. Evidently, the samples with ultrasonic assisted osmotic pretreatment showed less drying time and more aromatic substances whereas the samples from the pulsed vacuum assisted osmotic pretreatment had better protein protection feature. Although the dried samples had higher ratio of bound water and better storage stability after these two pretreatment methods, from the point of view of increasing drying rate and stimulating flavor substances, the ultrasonic assisted osmosis pretreatment method had more advantages. The research outcomes can contribute to optimize better pretreatment methods for the process of heat pump dried Tilapia fillets. 相似文献
18.
The drying kinetics of poplar lumber was experimentally investigated as a function of drying temperature (115, 135, 160, 185 and 205°C) during a periodic hot-press-drying process. Poplar lumber was dried under contact (compression ratio of 10%) and high-press states (compression ratio of 44%). Compared with the contact-state, the high-press-state showed higher drying rate and higher efficiency of removing free water than bound water in wood. Eight mathematical models from the literature were established to analyze the drying behavior. The Weibull model, with an average determination coefficient R2 of 0.9958, fitted well for all applied drying conditions. The scale parameter decreased with increasing drying temperature and was lower for high-press-state drying compared with that for contact-state drying. Moisture diffusivity and activation energy were calculated according to the Weibull model. Diffusivity increased with increasing drying temperature, with the average value of 1.734?×?10?6 and 3.313?×?10?6?m2/s and activation energy of 34.79 and 32.85?kJ/mol for contact-state drying and high-press-state drying, respectively. Hot-press drying created an M-shaped curve of density distribution, with high density at the two surface regions gradually decreasing toward the core region. The contact state-dried wood showed increased density near the wood surface. Both average density and peak density improved in the case of high-press-state-dried wood. Furthermore, the hydrophilic index of wood for high-press-state drying was lower than that of the contact-state drying, and the opposite was true regarding crystallinity index. The hygroscopicity of high-press-dried poplar decreased with lower equilibrium moisture content and higher moisture excluding efficiency, compared with contact-state-dried poplar. The rapid, high-quality drying of poplar lumber through periodic hot-press was more potentially achieved by the high-press-state compared with contact-state drying. 相似文献
19.
ABSTRACTThis study determined the proximate composition, phytochemical and antioxidant activity of the edible red seaweed, Kappaphycus alvarezii, under different drying conditions, namely, oven dried, sun dried, vacuum dried, and freeze dried. The proximate composition of K. alvarezii has shown no significant difference (p?>?0.05) in macronutrient components except fat content. Phytochemical studies conducted on total phenolic content and total flavonoid content showed that vacuum-dried extracts demonstrated the highest total phenolic content at 12.97?mg?PGE?g?1 DE. In vitro antioxidant activities of seaweed extract by ferric-reducing antioxidant potential and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity proved that oven-dried extracts showed the highest ferric-reducing antioxidant power value, 272.95?µM TE mg?1, and highest scavenging activity, EC50 9.55?mg?mL?1. In general, sun-dried extracts showed lowest antioxidant among all treatments. 相似文献
20.
AbstractMicrowave rotary drum drying of whole garlic bulbs was investigated for the Aspergillus niger inactivation and moisture removal. The Weibull and Bigelow models were applied to microbial inactivation data. Garlic bulbs with initial moisture content in the range 1.95–2.14?g water g?1?dry matter were dried up to 0.06?g water g?1?dry matter. The microwave power density (PD) was varied from 1.03 to 2.67 Wg?1 at 1.5 and 2.0 pulsation ratios (PRs). Effect of PD and PR on A. niger inactivation, product temperature, moisture diffusivity, moisture ratio, drying rate, color, and sensory parameters was studied. Page model was found to be a better fit for microwave rotary drying characteristics of whole garlic bulbs. Microwave rotary drum drying resulted in the average log reduction of A. niger between 1.12 and 1.60. Weibull model predicted A. niger inactivation better than the Bigelow model as it considered the nonlinearity associated with a microbial population in the sterilization process. Garlic powder prepared at 2.0 PR and 1.85 Wg?1 PD was chosen as the best process based on sensory score. The cracking and peeling of garlic cloves were observed during microwave rotary drum drying. The SEM images confirmed the increase in the pore size of the microwave treated garlic sample than the untreated garlic which might be the reason for cracking and loosening of peel in garlic. 相似文献