Effect of Drying Process Parameters on Dehydrated Cabbage Enriched with Selenium

Cabbage (Brassica oleracea var. capitata L.) enriched with selenium through foliar spraying was used to study the effect of drying process on its selenium retention and other quality criteria. Parameters such as blanching, seasoning, temperature, pH, and time of treatment were studied and evaluated to obtain an optimal processing condition for dehydrated selenium-enriched cabbage. After blanching, the barrier for mass and heat transfer of cabbage cellular materials became lower so that the heat damage was high. Blanching parameters set at 95°C and 60 s retained selenium and vitamin C in cabbage best as well as inactivated enzymes present in cabbage. Seasoning reduced the water activity of cabbage and subsequently reduced the loss of selenium. Blanching and seasoning could prevent browning deterioration of cabbage and reasonably kept the fresh color. The selenium loss kinetics during drying obeyed the first-order reaction and its activation energy was 44.0 kJ mol^?1.     

Effect of Sugar Pretreatment on Quality of Dehydrated Cabbage

To reduce the cost of osmotic treatment with glucose and fructose in production of dehydrated cabbage, use of a low-price additive, namely, high-maltose syrup, as an osmotic agent was investigated. The results showed that high-maltose syrup had more efficient dehydration and osmosis capability than fructose. Effect of additives on drying rate at 80 and 65°C was also investigated. Osmotic pretreatment with high-maltose syrup was helpful in reducing energy consumption and for enhancement of the drying rate.     

Effect of Sugar Pretreatment on Quality of Dehydrated Cabbage

To reduce the cost of osmotic treatment with glucose and fructose in production of dehydrated cabbage, use of a low-price additive, namely, high-maltose syrup, as an osmotic agent was investigated. The results showed that high-maltose syrup had more efficient dehydration and osmosis capability than fructose. Effect of additives on drying rate at 80 and 65°C was also investigated. Osmotic pretreatment with high-maltose syrup was helpful in reducing energy consumption and for enhancement of the drying rate.     

Effects of Acetic Acid Pretreatment and Hot Air Drying on Resistance of Salmonella on Cabbage Slices

The heat resistance of Salmonella anatum inoculated onto the surface of cabbage slices as affected by acetic acid pretreatment (0.5–1.5% v/v) and hot air drying at 50–60°C was investigated. Approximately 1.5 log₁₀ of Salmonella numbers was reduced after soaking the vegetables in acetic acid solution. The inhibitory effect of acetic acid on the bacteria was more pronounced during drying. The heat resistance of Salmonella on the cabbage surface treated with acetic acid decreased considerably compared with untreated cabbage. Moreover, the vegetable treated with higher acetic acid concentration resulted in a higher degree of acid injury and hence increased the susceptibility to heat during drying. The results revealed that acetic acid pretreatment may be used as an additional processing step to increase the safety margin of dried vegetable products.     

流态化干燥过程的分析

通过物料在流化床干燥器上的热态实验,找到了对物料干燥过程产生影响的因素,根据实验数据和理论分析给出了应采取的有利措施。     

纸张脉动燃烧尾气冲击流干燥过程的实验研究

脉动燃烧因其传热效率高、结构紧凑、环境污染小等优点而广泛应用于生产生活中,冲击干燥同样也能形成强烈的热质交换,本文将上述两种干燥技术结合应用。为了探讨脉动燃烧尾气冲击流干燥的性能,研制了小型Helmh01tz脉动燃烧器,并对脉动燃烧尾气冲击流干燥技术应用于纸张的干燥过程进行了实验研究。分析了气流辐射半径和燃料流量两个参数对干燥过程的影响,可以看出随着气流辐射半径的增加,干燥速度降低。此外还对不同干燥条件下的纸张干燥时间进行了估计,为实际生产提供参考。     

三角枫在干燥条件下的诱发变色过程

三角枫是一种易变色的木材，干燥过程中的变色不易预防；若能使三角枫干燥后得到更为理想的颜色，则可获得更为广泛的应用。通过对三角枫在不同干燥工艺条件下变色过程的研究以及红外光谱与扫描电镜分析，得出了三角枫干燥过程中的最佳诱发变色条件和诱发变色机理。研究结果表明，三角枫在干燥过程中的诱发变色是可行的。三角枫干燥过程的诱发变色机理为：①高温、高湿加速了三角枫中多元酚类物质以及无色花色素与单宁等的氧化反应，使三角枫发生红色变色；②三角枫经饱和蒸汽处理，羟基-OH经氧化转化为羰基-C=O、羧基-COOH、酯基和酮基等，使三角枫发生变色。     

Studies on the Microwave Freeze Drying Technique and Sterilization Characteristics of Cabbage

The vacuum freeze-drying (FD) technique used in the food industry can yield a high-quality product, but it is very expensive and requires a long processing time. Besides, the quantity of microorganisms in FD products can often exceed the required standard. As a result, it will be important to develop a new freeze-drying technique. In this article, cabbage was used as a model material, and the microwave field was used as a heat source to supply sublimation heat so that the drying time was shortened greatly. The effect of the microwave sterilization during the drying process was evaluated. Effects of the pressure, thickness of material being dried, and the input microwave power on such indices as drying time and the microorganism number were studied. Compared with the method of ordinary freeze drying, microwave freeze drying (MFD) can greatly reduce the drying time and has a notable sterilization effect.     

Effect of Different Drying Methods on the Microwave Extraction of Phenolic Components and Antioxidant Activity of Highbush Blueberry Leaves

In the last few decades, researchers have found blueberry leaves to be an interesting source of different phenolic compounds, and drying is an important part of their postharvest and sample preparation processes. In the current study, blueberry leaves were dried using microwave-assisted hot air drying or hot air drying alone at 45, 60, and 75°C to 10–15% wet basis. Corresponding drying characteristics were determined by fitting the moisture ratio obtained in each case with eight theoretical and semitheoretical models for hot air and microwave drying stages. It was observed that best fitting drying models for blueberry leaves depended not only on the nature of the biomaterial but also on the method of drying and the temperature of drying. Phenolic content, monomeric anthocyanin content, and the corresponding antioxidant activity in terms of 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition activity and ferric reducing ability of plasma (FRAP) activity were evaluated for the leaf extract obtained following microwave extraction of the dried samples obtained using the above-mentioned drying methods and were compared to the corresponding bioactive compositional characteristics of freeze-dried blueberry leaves. It was observed that the freeze-dried sample had the highest content of total phenolics and total monomeric anthocyanins along with high antioxidant activity. Furthermore, extracts obtained from the microwave-dried leaf samples obtained with a drying temperature of 60°C had highest total phenolic content and highest total monomeric anthocyanin content among all other drying methods and the extract had an antioxidant activity similar to the freeze-dried blueberry leaf samples, implying that microwave drying at 60°C is a potential alternative to freeze drying for preservation of the phenolic components and antioxidant activity of dried blueberry leaves.     

Studies on the Microwave Freeze Drying Technique and Sterilization Characteristics of Cabbage

The vacuum freeze-drying (FD) technique used in the food industry can yield a high-quality product, but it is very expensive and requires a long processing time. Besides, the quantity of microorganisms in FD products can often exceed the required standard. As a result, it will be important to develop a new freeze-drying technique. In this article, cabbage was used as a model material, and the microwave field was used as a heat source to supply sublimation heat so that the drying time was shortened greatly. The effect of the microwave sterilization during the drying process was evaluated. Effects of the pressure, thickness of material being dried, and the input microwave power on such indices as drying time and the microorganism number were studied. Compared with the method of ordinary freeze drying, microwave freeze drying (MFD) can greatly reduce the drying time and has a notable sterilization effect.     

天然气长输管道干燥剂干燥投产工艺分析

干燥剂法干燥投产在陆上和海底输气管道投产中应用较为普遍。清管器的运行控制是干燥过程的一个重点和难点,必须准确的估算清管器运行压降,同时干燥剂的窜漏量也是一个十分关注的参数。概述了干燥剂法干燥工艺过程,重点分析清管器运行压降和窜漏量的理论计算方法,为干燥设计和施工操作提供了理论指导与依据。     

Waste Heat Integration of Coating Paper Machine Drying Process

The paper sheet drying process consumes about 70% of the total energy required in coated papermaking, and almost all the thermal energy used in the process can be found in the exhaust air; thus, it has significant potential to recover the heat. With the aim of saving energy, the recovered energy is usually used to heat different process streams instead of steam.

This article examines the drying process of an operating coating paper machine to demonstrate an optimization method. To study the possibility of improving energy efficiency, thermodynamic analysis was conducted. The reasons why there is so much heat lost during drying were investigated. Based on the results of the energy and exergy analysis, a new waste heat integration scheme is presented. Furthermore, the performance of the proposed scheme has been evaluated. The results of the case study show an energy efficiency improvement of 7.3% and a specific energy consumption reduction of 4.6% with profitable investments.     

Effect of Osmotic Treatment on Drying Kinetics and Antioxidant Properties of Dried Mulberry

Air drying is widely used in fruit preservation. However, this causes a reduction in the nutritive value of the product. Osmotic treatment has been used as prior to drying. The objectives of this research were to study osmotic treatment in combination with air drying of mulberries and to evaluate the influence of different osmotic solutions on drying kinetics, reaction kinetics, and antioxidant capacity, with a focus on anthocyanins and phenolics. Mulberries, either untreated or osmotically treated with sucrose, sorbitol, and maltose, were dried in a tray dryer at 60°C with a velocity of 1 m/s. The drying kinetics of mulberries were explained using the Page model based on the R ² values, which ranged from 0.985 to 0.993, and E _s , which ranged from 0.031 to 0.091. Air drying caused degradation of anthoyanins and phenolics, which followed a zero-order reaction with R ² values ranged from 0.866 to 0.996. Osmotic treatment with maltose was found to be a good treatment for mulberry drying and preserved the phenolic and anthocyanin contents and provide high antioxidant capacity.     

Effect of Water on the Quality of Dehydrated Products: A Review of Novel Characterization Methods and Hybrid Drying Technologies

The effect of water on the quality of dried products is reviewed in light of recent applications of novel characterization methods (nuclear magnetic resonance (NMR), X-ray spectroscopy, and Raman spectroscopy) in quantifying the state and mobility of water in dried products. The mechanical configuration and ability of a number of hybrid drying technologies that use novel heating sources (microwave, infrared, radiofrequency) and/or sub-atmospheric pressure in producing better-quality products are reviewed in considerable detail. The drying kinetics models, especially those related to the quality loss, are also reviewed. It appears that more and more drying research is now focused on the development of novel hybrid technologies to produce better-quality products and for energy savings. The novel characterization technologies listed above are capable of quantifying the dynamic mobility and state of water in dried food products; this information can be used to design more efficient drying processes.     

Model Predicted Effect of Process Variables on Kiln Drying of Pinus radiata Boards

The effects of kiln-drying process variables on drying time and final moisture content (MC) variability were assessed using a mathematical drying model (a kiln-wide model) developed earlier. Drying time was predicted to decrease by using higher air velocities and temperatures and, to a less extent, by increasing fan reversal frequencies. The drying time extended as board thickness or stack width increased. Increase in air velocity from 5 to 8 m/s tended to minimize the final MC variability. At least three reversals in the early stages of drying were required to reduce final moisture contents variation. The final MC variability increased with increasing stack width and with increasing temperature.     

Model Predicted Effect of Process Variables on Kiln Drying of Pinus radiata Boards

The effects of kiln-drying process variables on drying time and final moisture content (MC) variability were assessed using a mathematical drying model (a kiln-wide model) developed earlier. Drying time was predicted to decrease by using higher air velocities and temperatures and, to a less extent, by increasing fan reversal frequencies. The drying time extended as board thickness or stack width increased. Increase in air velocity from 5 to 8 m/s tended to minimize the final MC variability. At least three reversals in the early stages of drying were required to reduce final moisture contents variation. The final MC variability increased with increasing stack width and with increasing temperature.     

Evaluation of the Sorption Equilibrium and Effect of Drying Temperature on the Antioxidant Capacity of the Jaboticaba (Myrciaria cauliflora)

In recent years, interest toward berries has increased (e.g., Myrciaria cauliflora or jaboticaba) because of their high phenolic content (phenolic acids, flavonoids, and anthocyanins) that has been associated with positive effects on consumer health and which play an important role in the antioxidant properties of food. This study analyzed the sorption isotherms, thermodynamic properties of sorption (isosteric heat and Gibbs free energy), and the evolution of the antioxidant capacity during the drying process. The effects of drying temperatures of 40°, 50°C, and 60°C on the antioxidant capacity and thermodynamic properties of sorption were evaluated. The gravimetric static method for sorption isotherm determination over a range of relative humidity levels from 0.10 to 0.90 was used. The sorption isotherms exhibited a Type II behavior, typical for many foods. The Guggenheim, Anderson, and Boer (GAB); Oswin; Peleg; and Lewicki models were used to fit the experimental data, and it was determined that the GAB and Peleg models were most appropriate for describing the sorption curves. The isosteric heat and Gibbs free energy were obtained from the experimental sorption equilibrium. The isosteric heat of adsorption decreased when the moisture content increased, while the Gibbs free energy increased. In addition, the phenolic content and antioxidant capacity increased while drying at 50°C and 60°C, whereas these factors decreased at 40°C. Our results provide the food industry with information concerning the best drying conditions to preserve antioxidant properties.     

Effects of Different Drying Methods on Bioactive Compound Yield and Antioxidant Capacity of Phyllanthus amarus

Phyllanthus amarus (P. amarus) has been used as a herbal medicine, particularly for liver support, in many countries and its extracts have been shown to possess potent antioxidant and anticancer properties in vitro. The preparation of dried sample is crucial for further extraction and isolation of phytochemicals. In this study, the effects of six different drying methods (hot air, low-temperature air, infrared, microwave, sun, and vacuum drying) on the phytochemical yield and antioxidant capacity were determined to identify the optimal drying method for P. amarus. The results showed that different drying methods, as well as different drying conditions within each method, significantly affected phytochemical yield and antioxidant capacity of P. amarus extracts. Infrared drying at 30°C was the best method for both retention of bioactive compound yield and antioxidant capacity of P. amarus extract, with 12 compounds were identified. In contrast, low-temperature-air drying at 25°C not only required the longest drying time but also significantly reduced the levels of bioactive compounds and antioxidant capacity of P. amarus. Therefore, infrared drying at 30°C is suggested for drying P. amarus for subsequent assessment of bioactivity.     

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%.     

传统水浴提取紫甘蓝红色素动力学研究

本文通过分析传统水浴提取紫甘蓝红色素的传质机理,建立了提取过程中紫甘蓝红色素得率与各工艺条件的动力学模型。经验证,所建立的动力学理论模型与实测数据相吻合,可良好地模拟色素提取过程,用于指导工业生产。