Drying of ultrasound pretreated apple and its selected physical properties

The aim of this work was to investigate the utilization of ultrasound as a mass transfer enhancing method prior to drying of apples tissue. Ultrasound power was provided at a frequency of 35 kHz for 10, 20 and 30 min in the ultrasound bath. Apple cubes were dried using convection method in 70 °C and at air velocity of 1.5 m/s. The effects of ultrasound pre-treatment upon drying were investigated.     

不同干燥方法对生姜粉物理性质的影响

以安徽临泉姜为原料,采用离心喷雾干燥、热风干燥、远红外干燥、真空冷冻干燥对新鲜生姜进行干燥制粉,研究干燥制粉后的生姜粉的物理性质。结果表明:喷雾干燥的生姜粉水分含量和容重较高,而得率、水合能力、吸油能力以及感官性能都是最差的;远红外干燥的生姜粉得率、水分含量、容重是最高的,水合能力、吸油能力及感官性能都较好;热风干燥的生姜粉水合能力最好,而得率、水分含量、容重、吸油能力和感官性能都紧次于远红外干燥的姜粉;真空冷冻干燥的生姜粉得率和水合能力居中,水分含量和容重最低,吸油能力和感官性能最好。     

纤维组合及组织结构对织物吸湿速干性能影响

采用Coolmax、Coolplus两种吸湿速干聚酯纤维，设计出不同纤维组合与组织结构的织物，并对织物的吸湿性与速干性进行了测试。结果表明：Coolmax、Coolplus纤维织物具有比普通聚酯纤维更好的吸湿性，比棉更好的快干性；随着织物中棉纤维含量的增加，织物的吸湿性提高，干燥性能下降；随着织物单位重量与厚度的增加，织物的干燥速率下降。     

Long-Term Storage Effects on the Physical Properties of the Potato

Determination of physical properties of agricultural products, such as the potato, and their variations during long-term storage, is an important feature in achieving high product quality and consumer acceptance. Physical properties of potatoes (Agria, Satina, and Caesar cultivars), including surface area, volume, moisture content, weight, and three main diameters of tuber, were measured and then other properties, such as sphericity, roundness, geometric mean diameter, volume mean diameter, aspect ratio, effective diameter, and real density during storage time, were calculated. The measurements were done every 15 days for a period of 22 weeks and analyzed based on a completely randomized block design in ten replications. Significant differences were observed among three potato cultivars according to major diameter, shape characteristics, mass, volume, and surface area of tubers. In this relation, Satina was larger in size compared to the two other cultivars. However, the Agria cultivar was closer to a sphere in shape. Also, it was found that the surface area of each potato could be estimated based on its mass and volume by a power law equation with a high coefficient of determination. According to the results, real density of tubers increased as a function of storage time based on a polynomial equation with R² = 0.99. During storage time, moisture content of tubers decreased according to a linear model and was probably the major rationale for decrease in tuber size. Density, size, and moisture content are the major physical characteristics of potato tubers, which change dramatically during long-term storage. Considerable differences in physical properties of different cultivars persuade researchers to carry out further studies on other popular potato cultivars.     

不同干燥方式对细菌纤维素物理性能的影响

本文考察不同干燥方式对细菌纤维素的物理性能的影响。采取3种不同干燥的方法分别对细菌纤维素膜进行干燥,分别为:60℃烘箱中干燥(BC-DHT);在-20℃冷冻结实后冷冻干燥(BC-FDF);在液氮中迅速冷冻结实,然后冷冻干燥(BC-FDN)。通过扫描电子显微镜观察,BC-FDN的内部结构比BC-FDF和BC-DHT更松散。在吸水性能方面,BC-DHT、BC-FDF、BC-FDN每克纤维素吸水量分别为2.38 g、6.22 g、58.24 g。在透湿率方面,BC-FDN的透湿性能最好,其次为BC-FDF,而BC-DHT透湿性能最差。对BC-DHT、BC-FDF、BC-FDN进行X射线衍射分析,从其衍射图谱分析所得结晶指数分别为78.5%、64.2%、47.5%。热重分析结果分析所得,BC-DHT的热稳定性较好,其次为BC-FDF,而BC-FDN的热稳定性最差。由此可见,通过不同的干燥方法能改变细菌纤维素的物理性质。     

四种干燥方式对小米椒理化性质及抗氧化能力的影响

为提升干制辣椒品质提供理论依据,本实验以小米椒为原料,研究冷冻干燥、自然晾晒、热风干燥和红外干燥对小米椒理化性质及抗氧化能力的影响,包括色泽、褐变度、果胶组分、游离氨基酸、总酚和抗氧化能力。结果表明,与冷冻干燥相比,自然晾晒、热风干燥和红外干燥均在一定程度上降低了干制辣椒的理化性质和抗氧化能力,表现在色泽劣变、褐变度升高、果胶降解、游离氨基酸含量和抗氧化能力降低等方面。与热风干燥和红外干燥相比,自然晾晒对干制辣椒品质的影响较小,其处理的样品色泽劣变较低;总酚含量和抗氧化能力维持在较高的水平。此外,自然晾晒的样品果胶降解程度较小,水溶性果胶、螯合性果胶和碱溶性果胶组分含量分别维持在22.39 mg D-半乳糖醛酸/g DW、1.22 mg D-半乳糖醛酸/g DW和16.17 mg D-半乳糖醛酸/g DW;游离氨基酸含量保持在11.860 mg/g DW。因此,自然晾晒能较好的保持干制辣椒的理化性质和抗氧化能力,相比于其他三种方式更适合于小米椒干燥。     

Thermophysical Properties of Okara During Drying

The simulation of heat transfer during thermal treatments of foods requires the knowledge of thermophysical properties of the material. In this study some thermophysical properties of okara, such as density, specific heat, thermal conductivity, thermal diffusivity, heat transfer coefficient, and mass transfer coefficient, were obtained during a drying process. Okara was extruded in the shape of spherical pellets and then dried in a fixed bed dryer from 78% of moisture content (w.b.) until 3%. During the drying process, the water content and the temperature of the samples were periodically measured. The thermal properties were obtained from empirical correlations found in the literature, which use the okara centesimal composition, analyzed in a laboratory, and the relative humidity and velocity of the drying air, measured during the process. The results in this study showed that it is possible to estimate the thermal properties cited using the experimental moisture content history and the centesimal composition of the food.     

气候和土壤及其互作对烟叶物理性状的影响

为探讨土壤和气候及其互作对烟叶物理性状的影响,在湖南烟区选择具有代表性的永州市、浏阳市、桑植县进行客土盆栽试验。结果表明:①不同物理性状指标受气候和土壤的影响强弱依次为单叶重、叶片厚度、平衡含水率、叶宽、叶长;其中,单叶重、叶片厚度、平衡含水率属中等变异强度,叶宽、叶长属弱变异强度。②土壤和气候及其互作效应对不同烟叶物理性状指标的影响不一样,叶长、叶宽、叶片厚度、单叶重主要受气候因子以及气候与土壤互作的影响,其中气候的影响最大,土壤影响可能性较小;平衡含水率主要受气候因子的影响,土壤以及气候与土壤互作的影响相对较小;气候对烟叶物理性状总变异贡献率为55.60%,土壤9.42%,气候与土壤互作为34.48%,气候是影响湖南烟区烟叶物理性状的关键生态因素。③大田生长不同时期的气候因子对烟叶物理性状影响的强弱不同,但都以地温影响最大。④土壤主要养分中全氮对烟叶物理性状影响最大;土壤中微量元素中有效钼对烟叶物理性状影响最大。     

干燥方法对山药粉性质的影响

通过真空干燥、冷冻真空干燥和喷雾干燥制备山药生/熟粉,研究其流变特性、糊化特性和消化性质,初步探究其变化机制。结果表明,山药生粉具有较高的成糊温度,山药熟粉中冷冻真空干燥山药熟粉的峰值黏度最高(3619.50 cP)。不同干燥方法干燥的山药粉均呈非牛顿流体特性,冷冻真空干燥的山药熟粉的粘弹性最高;山药生粉呈现完整的淀粉颗粒形态,山药熟粉的颗粒形貌差异较大。熟化处理使山药粉抗性淀粉含量显著降低(P<0.05)。熟粉中真空干燥山药熟粉的抗性淀粉含量最高(56.11%)。三种干燥方法中,冷冻真空干燥能较好的保留山药粉的原有理化特性。     

Effect of Pomace Drying on Apple Pectin

The effect of temperature used for drying apple pomace on apple pectin characteristics, including chemical composition, color and gelpoint temperature (T_g) was determined. Pomace was obtained from commercial Granny Smith apples and dried in a rotary drier at different air temperatures (T_dr = 60, 70, 80 and 105 °C). Pectin was extracted from dried pomace in nitric acid solution (pH = 2.5) at 80 °C. Major minerals in apple pectin were Ca>Na>Mg. Galacturonic acid content (% AGA=60.6±1.8) was practically unaffected by drying temperature. Conversely, T_dr affected both the degree of methoxylation (DM) and the molecular weight (M_w) of extracted pectin. M_w was estimated by applying the Mark Houwink - Sakurada equation, through determination of intrinsic viscosity of pectin solutions. M_w reduced withT_dr from approximately 122,000 (60°C) to 57,000 (105°C). Pectin color, as Hunter ΔE, was also affected by T_dr. A lighter color was obtained at 80°C. The higher gelpoint value (T_g= 80°C) was obtained with pectin from pomace dried at 80°C. Gelpoint was shown to be more sensitive to T_dr than other quality parameters: while DM had the same value both at 80 and 105°C, minimumT_g occurred at the higher temperature. T_g was also very sensitive to pH.     

不同烘干工艺参数对玉米品质的影响

针对不同含水率的玉米烘干过程中烘干温度和烘干时间影响玉米品质的问题,本文选取玉米的电导率、脂肪酸值、淀粉得率为玉米品质关键指标,研究了烘干温度、烘干时间、玉米初始含水率三个因素对玉米品质的影响。为使试验数据具有实际参考价值,烘干过程模拟实际烘干作业工艺,采用烘干-缓苏-烘干-缓苏-烘干-缓苏的方式。在单因素试验基础上,采用响应面分析法对玉米烘干参数进行分析、优化。试验表明：响应面分析所得模型预测误差小于10%,可以用于指导生产实践;影响玉米品质的显著性顺序为烘干温度>烘干时间>初始含水率;通过选取电导率差值最小值、脂肪酸值最低值和淀粉得率的最高值,得出在不同含水率情况下的最优烘干参数组合,如：初始含水率为21%时,单次烘干时间7.7min,烘干温度49.4℃。     

干燥方式对苜蓿超微粉物化特性及抗氧化活性的影响

为研究不同干燥方式对苜蓿超微粉物化特性及抗氧化活性的影响,以苜蓿超微粉总色差为指标,采用正交实验法,确定苜蓿超微粉的最佳护色方法,优化热风干燥工艺参数;通过测定苜蓿超微粉粒度、溶解度、持水力、持油力、DPPH自由基清除率等理化指标,比较热风干燥和真空冷冻干燥得到的苜蓿超微粉之间的物化特性和抗氧化活性差异。结果表明,采用热风干燥法干燥苜蓿的最佳工艺参数为:干燥温度70℃、干燥时间8 h,护色剂为0.15% L-半胱氨酸时,此条件制备的苜蓿粉具有较好的物化性质。并且苜蓿超微粉粒度的减小能明显提高苜蓿粉的抗氧化活性。真空冷冻干燥苜蓿超微粉具有很好的物理化学特性,经过干燥粉碎后能够很好的保留其中的营养价值和抗氧化活性,但其时间和能源消耗较大;而热风干燥苜蓿粉的物化特性及抗氧化活性相对较差,但其干燥时间短,能源消耗较少。     

不同热风干燥温度对扇贝柱干燥特性及品质的影响

对海湾扇贝贝柱进行了热风干燥试验,研究了在45℃,55℃和65℃等不同热风干燥温度下扇贝柱的干燥特性,并对所得干制品在品质和营养成分上进行了比较分析。结果发现,热风干燥温度越高干燥速度越快,水分活度(Aw)下降的也越快,在较高温度下的干燥时间要比较低温度下的干燥时间至少缩短5 h。但较高热风干燥温度下得到的样品与较低温度下的相比,其黏聚性、咀嚼性增大,样品亮度降低,粗蛋白含量较低,对口感、感官等品质造成不利影响。     

水性油墨热风干燥机理及数学模型研究

当前,随着人们对环保及食品、药品安全问题越来越重视,绿色印刷与包装技术的研究和应用也越来越广泛,其中水性油墨逐渐被市场接受。但是,目前国内与水性油墨配套的印刷发备多数存在烘干效率低,从而导致印刷速度难以提升的问题。为解决此问题,本论文以Logarithmic模型为基础,分析水性油墨的热风挥发干燥机理和过程。在热风温度为50℃,热风流速为6m/s的条件下,假设实验条件遵循费克第二定律:干燥初始阶段,固体基质的流体均匀分布;干燥过程中,扩散系数保持不变;表面传热传质阻力忽略不计以及保持体系一维扩散等。在该实验条件下,对水性油墨在干燥过程中残留流体比例进行测量并记录,然后对实验数据进行非线性回归(Orign统计软件),以相关系数的平方作为评价模型的依据,并对Logarithmic模型进行修正,得出与水性油墨干燥过程吻合的改良模型。最终模型能够准确预测水性油墨干燥效率,而且能够为水性油墨印刷设备的设计提供基础数据,同时,对相关印刷设备印刷速度的提高具有积极意义。     

热风风速和相对湿度对扇贝柱干燥特性及品质的影响

本试验以海湾扇贝柱为原材料,进行薄层干燥试验,研究恒定风温下不同热风风速、相对湿度对产品干燥特性和品质的影响。测定干燥过程中水分含量和水分活度（Aw）的变化,并对所得产品的收缩率、复水率、色泽、质构等品质特性进行了比较分析。结果表明, 整个干燥过程均处于降速干燥阶段,起始阶段干燥速率下降最快,随着干燥时间的延长,干燥速率逐渐平缓。提高风速、降低热风相对湿度都可以显著缩短干燥时间,水分活度（Aw）下降速也越快。不同热风风速和相对湿度对干贝的质构特性、收缩率和复水率也有显著影响,但是对干贝色泽影响并不显著。综合考量干燥速率和干制品品质,选择热风风速为0.8~1.2 m/s、热风相对湿度在8%左右为较适宜的海湾扇贝柱热风干燥条件。     

蒸气喷射真空干燥技术及其设备的研究

蒸气喷射真空干燥技术和设备,以其投资少,效率高,能耗低,产品质优价廉,使用潜力大,范围宽,结构简单,工作性能可靠等优点,获得了良好的推广应用价值和广阔的发展前景。     

食品冷冻干燥速率分析

针对食品冷冻干燥过程中,存在过程速率慢,生产周期长的问题,对影响食品冷冻干燥的传热传质速率的诸因素从理论上进行了综述、分析,为食品冷冻干燥技术的进一步研究、应用提供一定的参考。     

Effects of insect-infested kernels on bulk flow properties of wheat

Insect damage to kernels during storage affects the processing quality of wheat and as well as bulk wheat properties, which in turn causes hopper flow problems such as funnel flow, ratholing, arching, or flushing. This study focused on kernel damage by Rhyzopertha Dominica F. (lesser grain borer), one of the most commonly found insects in wheat, and resulting changes in physical properties, such as bulk density, tapped density, true density, and angle of repose, and in flow properties, such as basic flowability energy, stability, aeration, compressibility, and permeability. Bulk and tapped densities of sound hard red winter wheat kernels and infested wheat kernels were about 720 kg/m³ and 775 kg/m³, respectively. Compressibility index (CI), Hausner ratio (HR), and angle of repose of infested wheat kernels were higher than for sound hard red winter wheat kernels, indicating decreased flowability. Grain dust and insect-infested kernels could form localized compacted areas within the grain bins, resulting in uneven flow during discharge. Results from this study indicate that the presence of insect-infested kernels could lead to arching and bridge formation in grain bins, thus affecting the flow characteristics of bulk wheat.     

Total phenolics,antioxidant activity,and functional properties of ‘Tommy Atkins’ mango peel and kernel as affected by drying methods

Mango processing produces significant amount of waste (peels and kernels) that can be utilized for the production of value-added ingredients for various food applications. Mango peel and kernel were dried using different techniques, such as freeze drying, hot air, vacuum and infrared. Freeze dried mango waste had higher antioxidant properties than those from other techniques. The ORAC values of peel and kernel varied from 418–776 and 1547–1819 μmol TE/g db. The solubility of freeze dried peel and kernel powder was the highest. The water and oil absorption index of mango waste powders ranged between 1.83–6.05 and 1.66–3.10, respectively. Freeze dried powders had the lowest bulk density values among different techniques tried. The cabinet dried waste powders can be potentially used in food products to enhance their nutritional and antioxidant properties.     

Effects of maturity and drying method on the physico-chemical and reconstitution properties of plantain flour

Effects of maturity and drying method on physical, physico-chemical and reconstitution properties of plantain flour were investigated. Colour ( L*a*b* ) parameters of dried flours were measured, and the delta chroma (Δ C ) and colour difference (Δ E ) were calculated. Particle size, physico-chemical (pasting) using Rapid Visco-Analyser and reconstitution properties of dried plantain flour were determined. Colour parameters of foam-mat [ L* (57.56–66.33), a* (5.29–6.77), b* (11.82–13.33)], sun [ L* (60.18–67.45), a* (5.43–5.88), b* (13.19–13.25)] and oven [ L* (58.78–66.44), a* (6.08–6.33), b* (11.96–12.78)] dried flours were significantly different ( P  < 0.05). Generally, more than 40% of the flours were retained by the 710 μm sieve. Generally, peak (–2.08–166.00), breakdown (1.25–29.42), final (–1.00–298.67) and setback (1.50–156.92) viscosities varied with drying method and maturity. Peak time and pasting temperature varied from 5.20–6.87 s and 92.30–94.55 ^°C, respectively. pH (4.26–4.97), titratable acidity (0.10–0.50% citric acid), soluble solids (3.25–30.76), moisture (8.77–65.99%) and dry matter (34.01–91.23%) contents were significantly ( P  < 0.05) affected by maturity and drying method.