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.     

QUALITY of ARTIFICIALLY DRIED LENTIL

The effects of artificial drying on Laird lentil qualities such as breakage susceptibility, cooking quality, and seed germination were determined at three initial moisture levels, 16%, 18%, 20% wet basis and seven levels of drying temperature varying from 40°C to 80°C. Cooking quality was not affected by drying in the range of treatments used in this study. High initial Omoisture content and lengthy drying periods at temperatures above 40°C were associated with increased seed breakage. Seed germination was particularly sensitive to heat treatment at 80°C and extended drying time for high moisture samples.     

微波干燥对芝麻品质特性的影响

研究微波干燥温度和干燥时间对芝麻的水分含量、发芽率及其油脂的酸价和过氧化值的影响,并利用固相微萃取-气质联用仪对处理后芝麻的挥发性成分进行了研究。结果表明:在低于90℃温度下干燥的前20 min内,芝麻含水量下降迅速,超过20 min后随着时间的延长,芝麻的水分散失速度逐渐变慢;微波干燥对芝麻的发芽率有破坏作用。干燥的前20 min内,温度低于80℃时,干燥温度升高对芝麻油酸值和过氧化值的影响不显著（p>0.05）,而温度高于80℃时,其对芝麻油酸值和过氧化值有显著影响（p<0.05）;随着干燥温度升高,干燥芝麻的主要挥发性成分烷烃类、萘类、酚类成分含量降低,醛类含量升高。      

Shelf Life of Sunflower Kernels

One raw and two oil roasted samples of sunflower kernels packaged in paper bags and in two types of low oxygen atmosphere pouches were stored at 5, 21 and 38°C. Quality of the stored samples was monitored by an expert sensory panel, peroxide, hexanal, free fatty acids and moisture determinations. Liking ratings, obtained with 99 consumers after 24 wk storage, were used to select end points for expert sensory ratings. The shelf life for roasted sunflower kernels was greater than 12 month when stored in nitrogen flushed pouches and as low as 8 wks when exposed to air at 38°C. Hexanal was a better index for shelf life of roasted sunflower kernels than was peroxide. The shelf life of raw sunflower kernels was > 12 month in packages providing some moisture but no oxygen protection.     

Effect of Lavender and Thyme incorporation in sunflower seed oil on its resistance to frying temperatures

Extending the frying life of oil is of commercial and economic importance. Therefore, improving the thermal stability of cooking oils could provide considerable savings to the food processors.In this study, three different frying temperatures i.e., 150, 180, 200 °C, were applied to refined sunflower seed oil before and after addition of two kinds of natural herbs. A number of official methods were used to evaluate chemical and physical changes in all samples during heating.Quality parameters of sunflower seed oil were improved by treatment with either Lavender or Thyme. In fact, the statistical analysis of results proved the existence of a significant difference between untreated and treated oil samples. However, no difference was found between sunflower oil with lavender and sunflower oil with thyme, whenever the same temperatures were applied. Thyme and Lavender exhibited a high ability in reducing free fatty acids content (FFA), peroxide value (PV), and Viscosity.The incorporation of Lavender and/or Thyme in sunflower seed oil helped to improve its thermal stability and, consequently, to extend its frying life.     

Influence of Wall Material and Inlet Drying Air Temperature on the Microencapsulation of Fish Oil by Spray Drying

Several single and composite milk-originated wall materials were used to microencapsulate fish oil via spray drying at various inlet drying air temperatures. Skim milk powder (SMP), whey protein concentrate, whey protein isolate (WPI), 80% WPI?+?20% milk protein concentrate, and 80% WPI?+?20% sodium caseinate (NaCas) were applied as the wall for capsules generated at drying air temperatures of 140, 160, and 180 °C. The higher the drying air temperature, the higher was the particle size, encapsulation efficiency, and peroxide value and the lower was the moisture content and bulk density. The microcapsules prepared with SMP showed the highest encapsulation efficiency and lowest peroxide value for the oil due to the presence of lactose in its chemical composition. Differential scanning calorimetry and Fourier transform infrared analyses indicated the absence of any significant interaction between SMP and fish oil.     

葵花籽油的氧化稳定性研究

以葵花籽油的酸值和过氧化值为评价指标,考察了温度、光照、金属离子、氧气、水分对葵花籽油氧化稳定性的影响。结果表明：温度、光照、金属离子、氧气、水分均会引起储藏过程中葵花籽油的酸值和过氧化值的升高,且温度和水分影响较明显;40℃下试样放置24 d后的酸值和过氧化值分别达到1.03 mgKOH/g和19.2 meq/kg;Cu2＋对于葵花籽油过氧化值的影响大于Fe2＋;氧气短期内不会促进葵花籽油酸值的上升;添加了1%和2%水分的葵花籽油的酸值相差不大,均大于未加水样品,且水分含量越高,过氧化值增加越快。     

Loss of essential oil of tarragon (Artemisia dracunculus L.) due to drying

The effect of hot air‐drying on the essential oil constituents and yield in French and Russian tarragon (Artemisia dracunculus L.) leaves was studied. The tarragon leaves were dried at air temperatures ranging from 40 to 90 °C. The drying stopped when the moisture content of the samples reached 10% or for some of the treatments reached 7, 20 and 30%. The essential oil of the fresh and dried leaves was isolated by hydrodistillation and analysed by capillary gas chromatography and gas chromatography–mass spectrometry. The decrease of oil during the drying process was highest at 60 °C drying temperature. For French tarragon the decrease in the amount of oil was significantly lower at 90 °C. The effect of the relative humidity of the drying air at each temperature was not significant. The main compounds were estragole in French tarragon (69%) and sabinene in Russian tarragon (40%). The drying process changed the relative percentage of the constituents in the oil; for instance, the relative percentages of estragole decreased and sabinene increased in French tarragon. Copyright © 2006 Society of Chemical Industry     

EFFECT OF HEAT TREATMENT ON THE INDUSTRIAL QUALITY OF TWO VARIETIES OF MEXICAN WHEAT

Two Mexican wheat varieties conditioned to three initial moisture levels (17, 25 and 37% dry basis) were dried with air at 40, 60, 80 and 100°C for 60 min periods in a laboratory scale fluidised bed system. Drying kinetics and activation energy was determined. Weight per hectolitre, wheat hardness, total protein content, dough mixing time and loaf volume were analysed. The results showed that the initial moisture content and drying velocity lowered the activation energy necessary to extract water from the grain. The effect of temperature and moisture content in the grain were the most important factors to control damage during drying. The hard wheat variety was less susceptible to heat damage than the soft variety, probably due to its higher protein content and harder texture. Weight per hectolitre, wheat hardness and drying did not considerably modify total protein content. Conversely, mixing time and loaf volume showed changes directly related to heat treatment severity. Fluidised bed drying at 40 and 60°C of both varieties at 17% initial moisture content showed an improving effect on loaf volume.     

Moisture content/relative humidity equilibrium of high-oil and confectionery type sunflower seed

Adsorption and desorption moisture equilibrium (m.c./e.r.h.) was determined for high-oil and confectionery type sunflower seeds. The seeds were exposed to various relative humidities which were controlled with environmental chambers. The equilibration data for both seed types were determined at 10 and 20°C. The two seed types yielded almost identical adsorption and desorption moisture curves at 10°C which indicated that seed physical and chemical properties had little effect on m.c./e.r.h. at this temperature. The “hysteresis effect” was evident at 10°C, desorption equilibrium moisture levels being higher than adsorption for both seed types. There was no apparent “hysteresis effect” in seed equilibrated at 20°C. At the higher temperature, the confectionery seed equilibrated to higher moisture levels than did the high-oil type, thus hull to kernel weight ratio, hull thickness, and oil content could affect m.c./e.r.h. at 20°C     

焙炒处理对不同植物油品质特性的影响北大核心CSCD

为了研究焙炒对植物油品质的影响,以油菜籽、亚麻籽、花生、葵花籽和芝麻为原料,经焙炒处理后采用液压压榨法制油(热榨油),分析植物油的理化指标(酸值、过氧化值、水分及挥发物、色泽)、主体组分(脂肪酸组成及含量、甘三酯组成及含量、挥发性组分)和总酚含量,并与未焙炒处理直接压榨制取的油(冷榨油)作对比。结果表明:热榨油酸值和过氧化值显著高于冷榨油(p<0.05),其中,热榨亚麻籽油酸值(KOH)最高(0.96 mg/g),热榨菜籽油过氧化值最高(1.02 mmol/kg);冷榨油水分及挥发物含量显著高于热榨油(p<0.05),其中冷榨花生油水分及挥发物含量最高(0.16%);热榨油的色泽较冷榨油深,其中热榨菜籽油的色泽最深(R1.1,Y31);焙炒对植物油脂肪酸和甘三酯组成及含量无显著影响(p>0.05);热榨油中醇类、醛类和酸类等挥发性组分较少,但杂环类物质较多;热榨菜籽油、亚麻籽油、花生油、葵花籽油和芝麻油总酚含量分别是其冷榨油的1.38、1.57、1.51、1.80倍和1.27倍。因此,焙炒对植物油品质影响较大,应根据生产需要选择合适的预处理方式。     

Moisture transport in birch lumber at low radio-frequency and contact vacuum drying

Results of the dynamic distribution of moisture content, temperature, and internal overpressure at low radio-frequency (LRF), up to 100 kHz, and vacuum contact drying are presented. To minimize structural changes of lumber, low temperature drying (less than 70 °C) was used. Contact vacuum drying with LRF volume heating decreases the moisture gradient compared to conductive vacuum drying and increases moisture removal rate by 25 %. The heat consumption energy and electrical energy for drying were determined. The significant influence of the internal overpressure on the moisture transport in birch lumber was proven.     

Moisture Diffusivity Determination of Different Parts of Longan Fruit

The components of the longan fruit were modeled as sphere for seed, cylinder for seed stalk, and slab for seed coat, shell, and flesh. The moisture diffusivities were determined by minimizing the sum of square of derivations between the predicted and experimental values of moisture content of thin layer drying under controlled conditions of air temperature and relative humidity. Experimental data were obtained from thin layer drying of the components in the form of sphere for seed, cylinder for seed stalk and slab for seed coat, shell and flesh. Air temperatures of 50, 60, 70, and 80°C and relative humidity in the range of 1.5–13.33% were used. The mean diffusivity of flesh of longan fruit increased with temperature, but the diffusivities of shell, seed coat, seed, and seed stalk were independent of temperature. The moisture diffusivities of shell and seed coat were much lower than those of the other parts of the longan.     

Batch drying of banana pieces — effect of stepwise change in drying air temperature on drying kinetics and product colour

Slices of banana were dried in a two-stage heat pump dryer capable of producing stepwise control of the inlet drying air temperature while keeping absolute humidity constant. Two stepwise air temperature profiles were tested. The incremental temperature step change in temperature of the drying air about the mean air temperature of 30°C was 5°C. The total drying time for each temperature-time profile was 240 min. The drying kinetics and temporal colour change of the products dried under these stepwise variation of the inlet air temperature were measured and compared with constant air temperature drying. The effects of the profile starting temperature and cycle time on both drying kinetics and product quality were also studied. It was observed that by employing stepwise-varying drying air temperature with appropriate starting temperature and cycle time, it was possible to reduce significantly the drying time to reach the desired moisture content with improved product colour.     

Effects of temperature and duration of storage on the degradation of malathion residues in dry rapeseed

Rapeseed containing up to 1 ppm malathion and ≤ 10% moisture was stored for up to 32 weeks at 10, 20 and 30°C to determine the time required to reach residue levels of 0.1 ppm. Malathion levels < 0.1 ppm were found only in seed at 20°C, 7.7% moisture content by 32 weeks and at 30°C, 7.1% moisture content by 16 weeks. The malathion degradation rates were related to calculated safe storage times to determine acceptable storage conditions. An improved analytical method of malathion extraction from rapeseed was developed. Manipulation of temperature ≤ 60°C for short periods was ineffective in lowering malathion residues to 0.1 ppm.     

Effects of drying conditions in hybrid dryer on the GABA rice properties

In this study, pre-germinated rough rice was dried under various conditions using a hybrid dryer that incorporated heat pump dryer with fluidized bed drying (FBD) system in order to compare with the single-stage drying by hot air dryer. The main objective was to investigate the effect of drying conditions on the cooking and physical properties, nutrients and sensorial qualities of GABA rice products. It appeared that the FBD at 100–140 °C led to noticeable increase of head rice yield. The germination process caused the decline of gelatinization enthalpy of brown rice flour, the change of pasting properties, the reduction of cooking time and escalation of the total phenolic content, antioxidant activity and GABA content. The FBD at higher temperature significantly raised the degree of starch gelatinization and caused longer cooking time, higher hardness and adhesiveness of cooked GABA rice. Three-stage drying comprising FBD at 60 °C for 10 min in the first stage followed by FBD at 100 °C in the second stage and then heat pump drying at 45 °C together with tempering step between drying stages was recommended due to its superior GABA rice product quality.     

Thin layer drying characteristics of rapeseed (Brassica napus L.)

This study was performed to determine the most appropriate thin layer drying model and the effective moisture diffusivity of rapeseed. The thin layer drying tests were conducted at three different combinations of drying air temperature levels of 40, 50, and 60 °C and relative humidity levels of 30, 45, and 60%. The thin layer drying characteristics of rapeseed were determined. The Page (1949) model was the most adequate model for describing the thin layer drying of rapeseed. Drying occurred in the falling rate period and the rate of moisture removal from rapeseed was governed by the rate of water diffusion to the surface of the seed. Effective moisture diffusivities were calculated based on the diffusion equation for a spherical shape using Fick’s second law. Effective moisture diffusivity during drying varied from 1.72 × 10⁻¹¹ to 3.31 × 10⁻¹¹ m² s⁻¹ over the temperature range. The dependence of moisture diffusivity on temperature was described by an Arrhenius-type equation. The activation energy for moisture diffusion during drying was 28.47 kJ mol⁻¹.     

蒙脱土对植物油脱色效果的综合评价北大核心CSCD

为了开发高效、环保的食用油脱色剂,以一种环保方法(半干法)生产的蒙脱土为研究对象,研究其在不同脱色条件(脱色温度、脱色时间和脱色剂添加量)下对大豆油、葵花籽油和菜籽油品质的影响。结果表明:该蒙脱土具有吸附色素和过氧化物从而降低油脂红值和过氧化值的作用,与脱色前相比,大豆油、葵花籽油和菜籽油的红值最大降幅分别为77.4%、92.3%和87.2%,过氧化值最大降幅分别为82.7%、83.2%和91.2%;蒙脱土用于3种植物油的脱色,植物油中总甾醇和总生育酚含量下降,而酸值总体上缓慢上升。进一步研究发现,在相同的脱色条件下,蒙脱土对大豆油、葵花籽油和菜籽油的酸值、总甾醇含量和吸油率的影响结果均优于活性白土,尤其是吸油率几乎是活性白土的一半。蒙脱土可替代活性白土用于对色泽要求不是很高的植物油脱色中。     

Thermo-mechanical properties of egg albumen–cassava starch composite films containing sunflower-oil droplets as influenced by moisture content

The effect of moisture content on the thermo-mechanical and structural properties of egg albumen–cassava starch composite films containing sunflower oil droplets was studied using dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Composite films were prepared by cold gelation, dried in a moisture controlled incubator (83.5%RH) at 25 °C for 8 days and aged at different relative humidity at room temperature (21 ± 1 °C) for 7 days to obtain composite films with moisture contents of 4%, 7%, 11%, 17% and 46% (dry weight basis). In DMA thermograms the magnitude of G′ and G″ increased with increasing temperature in high-moisture samples, decreased and then again gradually increased for intermediate-moisture samples, and decreased in low moisture samples. DSC thermograms indicated two distinct peaks (at 49–53 °C and 79.8 to 132.4 °C) which were attributed to phase transitions and protein denaturation. SEM images indicated that the microstructure of the composite matrix changed with moisture content and heating temperature. Our study confirms that moisture content plays a key role in the thermo-mechanical properties and microstructure of egg albumen–cassava starch composite films containing sunflower oil.     

包装葵花籽油氧化稳定性研究

研究了包装葵花籽油初始过氧化值、顶空部分的残氧量和温度对保质期内葵花籽油氧化稳定性的影响。结果发现:氧气和高温共同作用会使油品加速氧化,在无氧状态下单纯高温对葵花籽油的影响不显著;灌装前葵花籽油初始过氧化值小于2.5 mmol/kg,能确保包装葵花籽油在最大残氧量的状态下,过氧化值在保质期内符合国家标准;瓶内顶空部分的残氧量越低,越有利于包装葵花籽油的质量稳定。