Quality aspects of heated-air drying of soybeans

Samples of 300 g of soybean seed, variety Forrest, conditioned to 14, 16 and 18% moisture content (m.c.; w.b.), were dried for 4 hr in a small batch fluidized-bed rig with a test section of 120 mm diameter and air flow rate set at 0.03 kg/s. Air inlet temperatures of 40, 50, 55, 60, 65, 70 and 80°C were used to determine the effects on quality. Conditioned and unconditioned samples, together with samples dried in the bed for 4 hr at room temperature, served separately as controls. Samples of 25 g of the conditioned seed, sealed in test tubes, were heated for 4 hr in an air oven at 40, 45, 50, 55 and 60°C to study the effect of heating at a constant m.c.Seed germination and seedling vigour clearly indicated the onset of heat damage and showed that no single criterion was more sensitive than any other. Safe drying air temperatures of 65, 60 and 55°C were obtained for initial moisture contents of 14, 16 and 18% respectively. Heating soybeans up to 60°C at a fixed m.c. increased the susceptibility to heat damage. Oil vield, free fatty acid content and fatty acid composition were not affected by any of the heat treatments. The peroxide value, however, showed some increase at temperatures above 50°C. Fluidizing at room temperature did not affect germination.The colour of crude oil, after heat bleaching, for 50–80°C heat treatments was paler than the controls, while 40°C gave a very dark colour. Degumming of oils followed by refining removed all detectable phospholipids from all samples and produced oils paler in colour, when heat bleached, except for 80°C at 16 and 18% m.c. which produced oils slightly but noticeably darker.Soybeans were found to dry slowly compared to sunflower seed and rapeseed, and the logarithmic drying model was fitted to the various drying curves. Computer program DRIER was modified to be applicable to soybeans and some runs were carried out for a farm batch radial-flow drier. Results indicated the advantage of using a high inlet air temperature provided that seed quality is not affected.     

采用振动流化床干燥卡拉胶的生产实践

将振动流化床干燥器应用于卡拉胶生产,结合卡拉胶干燥特性和流化床的结构特点,给出了干燥工艺的主要操作参数操作温度95~110℃,压榨程度含水82%以下,料层厚度进料5~6mm、出料1~1.5mm。     

热泵式流化床干燥装置及其应用优势

热泵式流化床干燥装置干燥食品的突出优点是节能和食品干燥质量好。本文对热泵式流化床干燥食品的特点进行了简要介绍，对热泵式流化床的结构性能进行了较深入的分析。对这种新型装备的推广与普及所需解决的问题及其技术思路进行了探讨，并对热泵式流化床食品干燥成套装备的市场应用前景进行了预测。     

Effects of drying and sterilization on the quality and shelf life of semimanufactured soybeans

Traditionally, soybeans are soaked in water for a dozen of hours in soymilk processing. To make instant soymilk, soybeans were semimanufactured (SM) by using different dehydration and sterilization methods, and their effects on the product quality and shelf life were investigated. Results indicated that the instant soymilk made from the SM soybeans using hot‐air drying and combined sterilization method exhibited the highest quality. The shelf life of the SM soybeans was determined to be 80 days at 25 °C and 180 days at 4 °C, based on their rehydration ratio, microbial load, and browning index. The SM soybeans only need to be rehydrated for 10 min before being prepared as soymilk, which is very convenient to consume at home and office.

Practical applications

Soymilk is nourishable and popular to many people worldwide. Besides purchasing processed products from supermarkets, people may choose to make it by themselves using the household soymilk grinder for freshness. However, the preparation is time‐consuming and a dozen of hours' soaking process of soybeans is necessary to obtain good quality soymilk. This paper presents an alternative to make instant soymilk, that is, by using semimanufactured (SM) soybeans, through presoaking, dehydration, and sterilization. Experimental results indicated that hot‐air drying and combined sterilization had many advantages over the other methods such as longer shelf life of the SM soybeans and better quality of the corresponding soymilk. The SM soybeans may have the potential to be commercialized to for consumers who prefer to make instant soymilk at home or office in a convenient manner.     

中间水分大豆振动-真空微波联合干燥过程的研究

为了进一步研究中等含水率物料的干燥特性,解决传统干燥方法中物料干燥不均匀、品质下降严重等问题,将振动和真空单元与微波干燥相结合,比较了干燥过程中微波功率、装载量和振动频率对含水率的影响.综合考察了同等条件下热风干燥、传统微波干燥、微波振动干燥和微波真空振动干燥的干燥特性结果表明:在真空度-0.065MPa以下,微波输出功率0.5～ 1.0W/g,传动电机转速350～550r/min的范围内,提高微波功率质量比、增加转速、优化装载量均有助于缩短干燥时间、提高干燥效率;振动-真空微波联合干燥与传统热风干燥相比能耗降低70％,与微波振动干燥相比爆腰率降低60％.在降低能耗量的同时保证了物料的干燥品质.     

间歇流化床干燥胡萝卜的研究

采用间歇流化床干燥胡萝卜 ,考察和分析了气体流量、进气温度、床层载荷、物料粒径以及烫漂预处理对干燥速率、产品质量及能量利用效率的影响 ,并对影响的过程和机理进行了详细的分析     

Effect of fluidized bed drying on properties of dehydrated apples

Three sorts of apple (Idared, Golden Delicious and Jonathan) were dried in a laboratory-type fluidized bed dryer. Apples were cleaned, cored, peeled and cut into 10 × 10 × 10 mm cubes or into slices 5 × 3 mm thick and 40 mm long. A part of the samples was dipped for 3 min prior to drying in 0.1% ascorbic acid solution. Drying temperature was 80 °C. Some physicochemical and sensory properties of fresh and dried apples were determined. Moisture content in dried samples varied between 9 and 12%. Greater quantity of water results in lower sensory characteristics. The sensory characteristics of apples were determined by a scoring system with weighed factors in a 20-point scale. Glucose, fructose, saccharose, citric acid, malic acid and ascorbic acid levels were analysed by enzymatic methods. Contents of glucose, fructose and saccharose in dried apples were substantially unchanged compared to fresh apples. The drying process had the most influence on contents of citric and malic acids. Higher rehydration ratios were measured in spaghetti-like sclices and in ascorbic acid treated samples. Idared had the best characteristics with regard to physicochemical and sensory results.     

蔗渣固定床干燥动力学模型的研究

在研究带惰性填料固定床干燥蔗渣的干燥特性及蔗渣平衡水分测定的基础上 ,构建其动力学模型 ,模型可为相关干燥器的发展提供支持。     

Modeling engineering characteristics of hazelnut kernel during infrared fluidized bed drying

In this study, a laboratory scale infrared fluidized bed dryer was used to dry the hazelnut kernels. The drying experiments were performed under the following drying conditions: air temperatures of 45, 65 and 85?°C, air velocities of 1.30, 3.09 and 4.87 m/s and infrared powers of 500, 1000 and 1500 W. Maximum and minimum values of effective moisture diffusivity for hazelnut kernels were obtained 1.87?×?10^?9 and 1.75?×?10^?10 m²/s, respectively. Activation energy was obtained between 33.02 and 50.22 kJ/mol. Specific energy consumption of hazelnut kernels was obtained between 1.72?×?10³ and 2.23?×?10⁴ MJ/kg. Six mathematical models were used to predict the drying behavior of hazelnut samples. Among these models, the Midilli model sufficiently fitted the experimental drying data. The shrinkage values were obtained within the range of 0.10 and 0.24. The results obtained showed that the \({{L}^{*}},\) \({{a}^{*}},\) \({{b}^{*}}\) and \(\Delta E\) color values of the kernels were significantly affected (P?<?0.05) by air temperature. The highest color changes were related to the air temperature of 85?°C at all air velocities and infrared powers. Maximum values of energy (103.57 N mm) and force (129.84 N) at initial rupture point was related to air temperatures of 85?°C and infrared powers of 1500 W. Minimum values of energy (16.47 N mm) and force (31.74 N) at initial rupture point was related to air temperatures of 45?°C and infrared powers of 500 W.     

Physical properties of parboiled wheat and bulgur produced using spouted bed and microwave assisted spouted bed drying

The main objective of this study was to compare the spouted bed and microwave assisted spouted bed drying on affecting physical properties of parboiled wheat and bulgur. Drying was performed at different temperatures (50 °C, 70 °C, 90 °C) and microwave powers (288 W, 624 W). Bulk and apparent density, bulk and apparent porosity, sphericity, color, microstructure and pore size distribution of parboiled wheat were investigated after drying. Yield and water absorption capacity were determined in bulgur samples. The effect of air temperature on physical properties of product except color was not significant in spouted bed drying. More porous structure was observed in wheat samples dried in microwave assisted spouted bed compared to air dried ones. Sphericity and bulk density were higher when high temperature was combined with high microwave power. In microwave assisted spouted bed drying, similar yield value but lower water absorption capacity of bulgur were observed as compared to spouted bed drying.     

Intermittent drying simulation in a deep bed dryer of yerba maté

In the present research, the reduction of energy consumption was evaluated during drying of yerba maté branches when tempering periods were applied. An empirical model was validated describing the moisture variation with time and process temperature, using different operation conditions. This model was used to simulate an industrial dryer in order to minimize energy consumption, maintaining the final moisture content constant. Best results were obtained working in the following conditions: application of heat for 15 min, 15 min of tempering and continuous application of heat. The bed height (1 m) was reduced in 10% maintaining the dryer production increasing the belt velocity. Working with these conditions a 10% of energy consumption can be reduced.     

Experimental and parametric study on drying of green peas in spouted bed

Drying of Green Peas (Pisum sativum) was studied experimentally in a lab‐scale spouted bed. Experiments were carried out at different operating conditions, and the effect of inlet air temperature and its flow rate, bed height (initial mass of wet particles) and average diameter of particles were examined on performance of dryer and rate of drying. The obtained experimental results were fitted by an exponential form equation to model the drying kinetic behaviour of green peas in a spouted bed. The fitting parameters are presented in the form of mathematical correlations as a function of operating parameters. As expected, it was found that by increasing inlet air temperature and air‐flow rate, the rate of drying increases, but by increasing the bed height and diameter of particles, the rate of drying decreases. The results can help the design engineers to choose the optimum drying conditions for industrial applications.     

喷动床在农产品干燥中的研究进展

农产品干燥是农产品加工业中一项非常重要的技术,为农产品原料的利用和新产品的开发提供了更多可能.能效和干燥产品的质量是农产品干燥的2个关键指标,喷动床干燥技术是这2个关键指标的有效提高途径之一.该文简述了喷动床技术在干燥农产品的应用中的研究进展,介绍了喷动床的结构、工作原理及其应用现状,分析了喷动床干燥农产品主要的优缺点...     

Experimental simulation of solar drying of garlic using an adsorbent energy storage bed

Solar drying of garlic with energy storage in silica gel is experimentally simulated in a closed system in which the air is continuously circulated between food and adsorbent. Kinetics of the drying process are studied and equilibrium data are predicted by a mathematical model developed from the experimental results. By comparing the end points of drying with equilibrium values the length of the drying process can be established.From sorption data, a garlic surface area of 63–188 m² g^?1 and a heat of adsorption in the first layer of 2548–2691 kJ kg^?1 have been calculated. A value of 746 kJ kg^?1 has been deduced for the activation energy for water removal.     

Improving ambient temperature stability of probiotics with stress adaptation and fluidized bed drying

Stabilization efficiency in terms of long term ambient temperature storage viability of the probiotic strain Lactobacillus casei CRL 431 was compared using freeze and fluidized bed drying techniques. Fluidized bed drying was able to retain 2.5 log cfu/g higher viability after 52 weeks of storage at 25 °C. A combination of fluidized bed drying and osmotic stress adaptation to the probiotic cells yielded further improvement of 0.83 log cfu/g higher viability compared to the unstressed cells. The findings were validated with other two lactobacilli and two bifidobacterium strains with probiotic characteristics and significant improvements in storage stability over freeze dried samples were observed. Fortification of vitamin E in the stabilization matrix as an antioxidant improved the stability by 0.18 log cfu/g during 20 weeks storage period at 25 °C, whereas any similar benefit of fortifying inulin as a prebiotic was not observed.     

Solid-substrate fermentation of soybeans with Rhizopus spp.: comparison of discontinuous rotation with stationary bed fermentation

Tempe is a soybean food obtained by stationary solid-substrate fermentation using moulds (mainly Rhizopus spp.) as starter organism. Traditionally, tempe is fermented in static layer trays or wrapped packages. Due to heat and mass transfer limitations, gradients of temperature and gas atmosphere will result. Agitated fermentation can help to level heat and mass gradients, yielding better homogeneity. This type of process will not result in traditional tempe, but in individually fermented soybeans that could be processed into food ingredients. This report deals with the comparative effect of stationary versus agitated solid-substrate fermentation of soybeans on some chemical indices of substrate modification. For agitated solid-substrate fermentation, a 450-l size rotary-drum bioreactor was designed and constructed. Of two Rhizopus spp. tested, R. microsporus tolerated agitation quite well, as judged by changes of pH, amino nitrogen, ammonia, and soluble dry matter. The other species, R. oligosporus was strongly affected by agitation. This resulted in less pH increase (difference approx. 1.5 units), lower amino nitrogen levels (30-50% of levels in static fermentation), and lower levels of water-soluble non-lipid dry matter (30-50% of levels in static fermentation) with R. oligosporus agitated fermentation of soybeans controlled at 30 and 37 degrees C, compared to static fermentation at temperatures ranging between 25-35 and 30-40 degrees C, respectively.     

Effects of fluidized bed drying temperature and tempering time on quality of waxy rice

Waxy rice, which is soft and sticky in nature, can be used as a raw material to produce many food products. After being harvested, high-moisture waxy paddy must be dried to appropriate moisture content to prolong its storage life and to achieve higher head rice yield. Fluidized bed dryer could be used to dry waxy rice at high-temperature. However, due to the high heat and mass transfer rates during drying, stresses are generated in a rice kernel, leading to crack and low head rice yield. Tempering is thus recommended to reduce the moisture-induced stresses in the kernel after rapid drying. In this study, the effects of fluidized bed drying temperature (90, 110, 130 °C) and tempering time (30–120 min) on the quality of waxy rice, i.e., head rice yield, thermal properties, pasting properties, color, translucent kernel and microstructure, were investigated. The results showed that head rice yield of waxy rice after drying was significantly lower than that of the reference sample even when tempering was performed. Higher drying temperatures led to higher head rice yield while the tempering time did not have any effect on the head rice yield except when the drying temperature of 90 °C was used. Drying at higher temperatures also affected the starch granule morphology and the pasting properties. Waxy rice changed its appearance from opaque white to translucent when being dried at 130 °C.     

Comparison of quality and microstructure of chokeberry powders prepared by different drying methods,including innovative fluidised bed jet milling and drying

Food Science and Biotechnology - The study assessed the functional properties, microstructural features and sensory characteristics of chokeberry powders obtained by the new fluidised bed jet...     

Effects of parboiling and fluidized bed drying on the physicochemical properties of germinated brown rice

Changes in physicochemical properties of germinated brown rice (GBR) and parboiled germinated brown rice (PGBR) dried in a fluidized bed dryer at 110–150 °C were investigated. Results indicated that parboiling altered the properties of GBR owing to starch gelatinisation. The moisture content, yellowness, peak viscosity and hardness of PGBR increased, but internal fissured kernel, cooking time, water absorption and total solids loss decreased when compared to GBR. γ‐aminobutyric acid (GABA) content in GBR was 23.31 mg per 100 g and was reduced to 17.91 mg per 100 g in PGBR. The drying times required to reduce the moisture content of GBR and PGBR to 16% d.b. were 4.01–7.65 min and 5.11–9.50 min, respectively. Final moisture content, which is optimum to prevent internal fissures of dried GBR and PGBR, was 27–29% and 25–28% d.b., respectively. The same trend was observed in the physicochemical properties of GBR and PGBR when increasing drying temperature and time.