Evaluation of infrared assisted freeze drying for strawberry snacks: drying kinetics,energy efficiency and quality attributes

Food Science and Biotechnology - Feasibility of infrared assisted freeze drying (IRAFD) was evaluated for production of the strawberry snacks. Infrared (IR) radiation provided the driving force of...     

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.     

响应面法优化竹叶精油的微波辅助提取工艺

目的:探讨通过微波辅助水蒸汽蒸馏法提取竹叶精油的工艺.方法:考察液固比、辐射功率、辐射时间等单因素对精油提取率的影响,并用响应面法进行优化,再对优化方案进行验证.结论:液固比30:1,辐射功率560W,辐射时间280s.结果:此条件下竹叶精油提取率可达0.589%.     

间歇微波—热风耦合干燥花生工艺优化及品质研究

为探究间歇微波—热风耦合干燥花生的最佳工艺参数,借助响应面优化分析方法,以花生干燥速率和干燥能效的综合评分为响应值,确定了花生间歇微波—热风耦合干燥的最佳工艺参数为:热风温度45 ℃,微波强度1.25 W/g,微波间歇比1.10。该条件下,花生间歇微波—热风耦合干燥速率为0.517 g/min,能效为0.433 MJ/g,干燥综合评分0.710,模型误差小于5%。基于此工艺参数探究该干燥方式对花生脂肪酶活动度、硬度、颜色和脂肪酸组成的影响。结果显示,间歇微波—热风耦合干燥是一种高效的干燥技术,能保证花生的品质。     

Grape marc phenolics: Extraction kinetics,quality and stability of extracts

The solid–liquid extraction of phenolic compounds from different vintage marcs with 60% ethanol was studied and experimental data were elaborated according to the different mathematical models applied in literature to recovery of bioactive constituents from plant materials. A first-order kinetics model was finally selected and the total phenolics diffusivities were calculated (1.23–1.50 × 10⁻¹⁰ m² s⁻¹).     

Moisture diffusivity and shrinkage of broad beans during bulk drying in an inert medium fluidized bed dryer assisted by dielectric heating

Drying behavior of broad beans (Vicia faba) was studied in a pilot scaled fluidized bed dryer with inert particles assisted by dielectric heating. The effective diffusion coefficient of moisture transfer was determined by Fickian method at four different air drying temperatures of 35, 45, 55 and 65 °C. Correlations for moisture diffusivity as a function of moisture content and temperature of the drying medium were developed. The values of moisture diffusivity were obtained within the range of 1.27 × 10^?9–6.48 × 10^?9 m²/s and the activation energies for FBD and FBD + DE were found to be 27.71 and 17.10 kJ/mol, respectively. The shrinkage behavior of the broad beans was also investigated by considering the volume ratio of (V/V_O) to be function of moisture content alone and fitting a polynomial of the third order. The dielectric heating power was also found to be effective on the rate of drying.     

金银花红外鼓风干燥特性、失水动力学及干制品品质研究

目的:研究金银花的红外鼓风干燥特性及其动力学模型。方法:金银花在不同温度（35、45、55℃）条件下进行红外鼓风干燥,计算水分比、干燥速率等参数,拟合建立干燥动力学数学模型,并测定干制品的色泽、主要成分等干燥特性。结果:金银花在红外鼓风干燥过程中,干燥温度越高,用时越短,降速阶段为其干燥的主要阶段。干燥的动力学模型拟合结果表明Page模型的预测值与实验值吻合性好,可以用来预测和描述金银花红外鼓风干燥的失水过程。费克第二定律求得干燥过程中的水分有效扩散系数（Deff）在5.06606×10-9⁷.59909×10-8m2/s内,且随温度的升高而增大;阿伦尼乌斯方程计算得出金银花红外鼓风干燥平均活化能为113.569 k J/mol。35℃时金银花的色差值ΔE最小,有效成分含量最高,与阴干相比可提高效率并保证产品质量。结论:金银花红外鼓风干燥的主要阶段为降速阶段,Page模型适于预测和描述其失水过程,35℃红外干燥与阴干相比可提高效率,且产品品质更优。      

微波干燥对青花椒挥发油含量的影响及工艺优化

以经过蒸汽灭酶的九叶青花椒为原料,研究微波功率、铺放量及间歇微波时间对微波干燥青花椒挥发油含量的影响。在单因素试验的基础上,以青花椒挥发油含量为响应值,根据Box-Behnken中心组合试验设计原理,进行优化试验设计,并建立青花椒的微波干燥回归模型。结果表明:青花椒微波干燥指标优化的条件为微波功率354.26W、铺放量211.93g、微波时间51.4s,该条件下青花椒干燥后挥发油含量为0.087 748 5mL/g,微波干燥验证实验结果与优化结果的误差为0.85%,优化结果可靠。