油炸过程中淀粉功能特性的变化

采用深层油炸模型,研究了油炸过程中淀粉的溶解度、膨胀度、冻融稳定性和透光率等功能特性的变化。结果表明,在试验范围内,初炸100 s的淀粉溶解度最高,其次是初炸75 s的淀粉,复炸80 s的淀粉溶解度最低。随冻融循环次数的增加,不同油炸处理淀粉的析水率均增大,但不同处理的淀粉析水率增幅不同;初炸25 s的淀粉糊析水率始终高于其他油炸处理的淀粉。当初炸时间在25~75 s时,淀粉的透光率随初炸时间的延长,而逐渐增大;随复炸时间的增加,淀粉的透光率却逐渐下降。     

油炸过程中淡水小龙虾理化性质与品质变化

研究分析油炸工艺（油炸温度（140、160、180、200 ℃）和油炸时间（15、30、45、60 s））对淡水小龙虾（虾壳、虾肉、虾黄）理化性质及品质的影响。测定淡水小龙虾中心温度、油炸损失率、色泽、质构特性、挥发性盐基氮（total volatile basic nitrogen,TVB-N）含量、硫代巴比妥酸反应物（thiobarbituric acid reactive substances,TBARs）值以及菌落总数（total plate count,TPC）的变化。结果表明：油炸温度对虾肉中心温度影响不显著,而油炸时间对虾肉中心温度影响显著（P＜0.05）;油炸温度180 ℃、油炸45 s时,虾肉中心温度可达到肌肉熟制标准温度;随着油炸温度升高及油炸时间延长,小龙虾油炸损失率显著上升（P＜0.05）;虾壳、虾肉、虾黄亮度值、红度值均呈上升趋势,而黄度值呈下降趋势;虾肉硬度、回复性、弹性、黏性、咀嚼性均显著增加（P＜0.05）;油炸过程中,虾肉TVB-N含量显著增加（P＜0.05）,但均低于10 mg/100 g,表明虾肉油炸后保持较好的新鲜度;虾肉TBARs值随油炸温度升高、油炸时间延长而增加,其中油炸时间对TBARs值影响较明显;新鲜虾肉初始带菌量非常高,油炸处理后虾肉TPC显著降低（P＜0.05）,油炸时间对虾肉TPC影响不明显。     

Development of Healthy Low-Fat Snacks: Understanding the Mechanisms of Quality Changes During Atmospheric and Vacuum Frying

Excess consumption of fat, a main component in fried food, is a key dietary contributor to coronary heart disease and perhaps some types of cancer. Although consumers are interested in healthier snacks, they are not willing to sacrifice organoleptic properties. Vacuum frying might be an alternative for the production of nutritious, healthy, palatable, and novel snacks. The objective of this review is to discuss the effect of atmospheric deep-fat frying on the main microstructural components and quality parameters of fried food, to understand how quality can be improved by lowering the operating pressure and, therefore, the processing temperature.     

真空油炸改善牛肉干品质的研究

将低温真空(减压)膨化技术应用于牛肉干的加工取得了很好的效果.探讨了油炸温度、时间和冷冻温度与时间对牛肉干制品质量的影响,并筛选出该工艺的最佳条件.     

煎炸油在薯片煎炸过程中的品质变化

以煎炸油为研究对象,以薯片为煎炸原料,研究煎炸油煎炸过程中理化指标变化及各指标间的相关性。结果表明:在煎炸过程中,煎炸油的折光指数、色泽、酸值、羰基值和极性值均随时间的延长而增大;过氧化值随着煎炸时间延长先增大后逐渐减小;碘值随时间的延长而降低;比重、黏度、皂化值在煎炸过程中的变化无明显规律。酸值、羰基值、极性值、色泽和折光指数彼此之间有极显著的正相关性,且相关系数均大于0.9;煎炸油极性值的变化可通过色泽和酸值进行预测。     

Determination of Mass Transfer Coefficients During the Vacuum Cooling of Pre-Cooked Meat Cuts

The influence of meat sample dimensions on the mass transfer coefficient (kS) of precooked cuts of pork, beef, and chicken during vacuum cooling, as well the behavior of this coefficient during the vacuum cooling process, were investigated. It was evidenced that the kS parameter presented statistical correlations with sample volume. The strongest dependence was found for precooked breast chicken, showing that this product can be cooled by vacuum impregnation. Knowledge of this dependence is important in order to evaluate the dimensions and geometric formats of meat cuts to be treated by vacuum cooling. Experiments with cylinders filled with moist sand showed that for porous materials kS can be considered proportional to the sample volume, and that the initial moisture content influences the internal temperatures during the cooling process. Knowledge of the kS behavior, with respect to sample volume, aids an understanding of the water evaporation and temperature decrease during the vacuum cooling of porous foods.     

香菇脆片真空油炸过程中传质规律

真空油炸过程中传质现象对真空油炸果蔬脆片的品质和安全控制极为重要.研究了油炸温度(80、90、100 ℃)、真空度(0.075、0.085、0.095 MPa)、预处理方式(漂烫,漂烫+浸渍+涂膜)对香菇脆片真空油炸过程中水分扩散和油脂吸收的影响,结果表明:香菇脆片的含水率随油炸时间的增加而逐渐降低,采用Pabis经验...     

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.     

Vacuum frying reduces oil uptake and improves the quality parameters of carrot crisps

Recent consumer trends towards healthier and low fat products have had a significant impact on the snack industry. The objective of this study was to examine the most important quality parameters of vacuum and atmospheric fried carrot slices in order to identify the specific advantages of vacuum technology. Said parameters include oil uptake, colour changes, and trans α and β-carotene degradation. Equivalent thermal driving forces were used (ΔT = 60 °C and 80 °C) to compare the processes, maintaining a constant difference in temperature between the oil and the boiling point of water at the working pressure. The results showed that vacuum frying can reduce oil content by nearly 50% (d.b.) and preserve approximately 90% of trans α-carotene and 86% of trans β-carotene. This process also allowed for the raw carrot colour to be preserved, which was reflected by good correlations between a∗ and trans β-carotene content, b∗ and trans α-carotene content, and hue and total carotenoid content.     

Determination of heat transfer coefficient during high pressure frying of potatoes

Besides traditional atmospheric frying, high pressure (super-atmospheric) frying might be an alternative approach to the frying of food products. In this study, convective heat transfer coefficient during atmospheric and high pressure frying was compared. For this purpose, a pressure cooker was modified to allow the immersion of a sample into frying oil under pressure and temperature measurement of sample and oil. Heat transfer coefficient versus frying time was determined on potato slabs using changes of total mass of the experimental set-up. At the pressure of 2 bar, the results showed an almost doubled heat transfer coefficient compared to the atmospheric pressure frying. The knowledge of heat transfer coefficient during pressure frying is expected to allow accurate determination of temperature distribution and hence the kinetic calculations to lead to development of an alternative frying process.     

胡萝卜脆片真空油炸脱水工艺的优化

研究了不同预处理条件及油炸温度、真空度、时间对胡萝卜脆片品质的影响.通过响应面分析可知:油炸温度、真空度及油炸时间显著地影响胡萝卜脆片中水分与脂肪质量分数、脆度,其最佳油炸工艺条件为温度100～110℃,真空度0.08～0.09MPa,时间15min.     

Physical and thermal properties of potato chips during vacuum frying

Vacuum frying (1.33 kPa), with the aid of a de-oiling mechanism, was used to produce low-fat potato chips.The kinetics of oil absorption and oil distribution in the potato chips was studied so that effectiveness of the de-oiling system could be established. Non-linear regression was used to fit the experimental data to the models used to describe oil absorption in potato chips with time.Moisture content, oil content, microstructure, diameter and thickness expansion, bulk density, true density, and porosity of chips fried at different temperatures (120, 130, and 140 °C) was performed to evaluate the effect of process temperature on the product. The convective heat transfer coefficient at the oil-chip interface was determined for the same temperature range.The final oil content of the potato chips was 0.072 ± 0.004, 0.062 ± 0.003, and 0.059 ± 0.003 g/g solid for frying temperatures of 120, 130, and 140 °C, respectively. These values are lower (80-87% less) than those found in the not de-oiled potato chips, which indicates that the de-oiling mechanism is crucial in vacuum frying processing. A significant difference (P < 0.05) was observed in oil content and oil distribution within temperatures. The rate of change in product quality attributes was greatly affected by temperature; however, the final values of moisture content, bulk density, true density, porosity, diameter shrinkage, and thickness expansion were not affected by temperature.During vacuum frying, the convective heat transfer coefficient changed considerably as frying progressed; moreover, it increased with temperature reaching a maximum between 2200 and 2650 W/m² K depending on frying temperature.     

油炸对鹅肉理化性质、质构与微观结构的影响

为选择鹅肉合适的油炸条件,采用常规物化特性测定方法,研究油炸对鹅肉理化性质、质构与微观结构的影响。结果表明,随油炸温度升高、时间延长,油炸损失率逐渐增加,135℃油炸5 min比120℃油炸2.5 min的损失率增加了12.87%(P0.05);p H值与剪切力的变化规律相似,呈现出了总体上升趋势,120℃与135℃油炸5 min时,剪切力值分别为40.432 N与55.783 N(P0.05);油炸后,鹅肉L*值降低,a*值与b*值逐渐增加,135℃油炸5 min的a*值与b*值分别比油炸2.5 min的增加了27.85%与32.95%;油炸后鹅肉硬度、咀嚼性总体变大,弹性、凝聚力、黏性及恢复性总体变小。120℃油炸3.5 min时,肌束膜内出现少许颗粒,125℃油炸3.5 min时,肌束膜变形严重,部分溶解,至135℃油炸5 min时,肌细胞结构已十分模糊。130℃油炸3 min是鹅肉较好的油炸条件,在此条件下,鹅肉损失率为38.24%、剪切力值为41.897 N、色泽金黄、质构特性良好。     

食用煎炸油理化指标统计分析方法研究进展

煎炸食品在愉悦味蕾的同时,也面临着油种类的最优抉择和质量安全问题,众多学者在选择何种类型的油,以及煎炸的时间长短方面进行了研究。本文从统计学的角度出发,概述了常用统计分析方法在煎炸油理化指标数据分析中的研究进展。一是,表格分析方式,大多数是将多次重复实验的数据以均值加减标准差的形式放到表格里进行研究,而且分析较多的理化指标是酸值、脂肪酸和极性化合物这三个指标。二是,作图可视化方式:直条图、折线图和散点图;其中,直条图主要用来展现在不同煎炸油、不同煎炸时间、不同煎炸温度、不同加热功率等条件下理化指标的含量情况;折线图主要用来分析理化指标随着煎炸时间、煎炸温度、不同煎炸油、不同煎炸负荷下理化指标的变化情况;散点图主要用来分析理化指标受煎炸时间、煎炸次数、油样密度等的影响,以及理化指标相互之间的关系和理化指标在不同废弃油样中的分布情况等。三是,拟合方式:线性拟合和非线性拟合;其中,线性拟合主要用来分析理化指标随煎炸时间、煎炸次数、介电常数变化等的线性关系,以及用来分析理化指标和近红外光谱之间的线性关系,分析理化指标实测值和其他模型预测值之间的一致性等;非线性拟合主要涉及到多项式拟合、指数函数拟合和逻辑回归的拟合,用来分析某些理化指标随煎炸时间变化的复杂关系,以及根据理化指标将油进行好坏分类等。四是,理化指标间的相关性分析,绝大多数文献是通过计算指标间的皮尔逊相关系数进行的,少部分文献使用了指标间的线性或者非线性拟合方式来分析。五是,针对理化指标数据进行的方差分析,主要用于研究不同煎炸因素下理化指标的变化情况。六是,针对理化指标进行的主成分分析,主要用来分析各个理化指标对煎炸油质量监控的重要性程度等等。通过以上对于煎炸油理化指标的统计分析方法的进展描述,给研究者们提供对于研究方法和研究手段的选择提供思路。     

Transport Mechanisms and Quality Changes During Frying of Chicken Nuggets—Hybrid Mixture Theory Based Modeling and Experimental Verification

Hybrid mixture theory (HMT) based 2‐scale fluid transport relations of Takhar coupled with a multiphase heat transfer equation were solved to model water, oil and gas movement during frying of chicken nuggets. A chicken nugget was treated as a heterogeneous material consisting of meat core with wheat‐based coating. The coupled heat and fluid transfer equations were solved using the finite element method. Numerical simulations resulted in data on spatial and temporal profiles for moisture, rate of evaporation, temperature, oil, pore pressure, pressure in various phases, and coefficient of elasticity. Results showed that most of the oil stayed in the outer 1.5 mm of the coating region. Temperature values greater than 100 °C were observed in the coating after 30 s of frying. Negative gage‐pore pressure (p^w < p^g) magnitudes were observed in simulations, which is in agreement with experimental observations of Sandhu and others. It is hypothesized that high water‐phase capillary pressure (p^c > p^g) in the hydrophilic matrix causes p^w < p^g, which further results in negative pore pressure. The coefficient of elasticity was the highest at the surface (2.5 × 10⁵ Pa) for coating and the interface of coating and core (6 × 10⁵ Pa). Kinetics equation for color change obtained from experiments was coupled with the HMT based model to predict the color (L, a, and b) as a function of frying time.     

油煎过程中猪排质构及感官品质的变化

研究加热过程中猪排质构和感官品质的动力学变化。将猪背最长肌沿垂直肌纤维方向切成1cm 左右厚度,在170～180℃油温下加热不同时间,冷却后比较各组质构和感官品质的变化。结果表明：随着加热时间的延长,肉块表面的亮度值显著下降,而中心亮度值明显增加;表面红度值显著增加,中心红度值则相反,并且在加热80s 时,肉块表面及中心红度值出现极点,高于前后红度值;加热过程中,肉块表面及中心黄度值均显著增加。样品中心温度和蒸煮损失增加,硬度呈阶段性增加,加热时间为100、120、140s 时,样品感官指标差异不明显。     

Applying an intelligent model and sensitivity analysis to inspect mass transfer kinetics,shrinkage and crust color changes of deep-fat fried ostrich meat cubes

The objectives of this study were to use image analysis and artificial neural network (ANN) to predict mass transfer kinetics as well as color changes and shrinkage of deep-fat fried ostrich meat cubes. Two generalized feedforward networks were separately developed by using the operation conditions as inputs. Results based on the highest numerical quantities of the correlation coefficients between the experimental versus predicted values, showed proper fitting. Sensitivity analysis results of selected ANNs showed that among the input variables, frying temperature was the most sensitive to moisture content (MC) and fat content (FC) compared to other variables. Sensitivity analysis results of selected ANNs showed that MC and FC were the most sensitive to frying temperature compared to other input variables. Similarly, for the second ANN architecture, microwave power density was the most impressive variable having the maximum influence on both shrinkage percentage and color changes.     

油炸过程中挂糊油炸猪肉片外壳食用品质的变化

采用深层油炸模型,利用色差仪、脂肪测定仪和质构仪等分析测试手段,研究了油炸过程中挂糊油炸猪肉片外壳的表观色度、水分含量、含油率及硬度、脆度和易碎性等质构参数的变化。试验结果表明,随油炸温度的升高和时间的延长,挂糊油炸猪肉片外壳的白度(L*值)逐渐降低,红度(a*值)和黄度(b*值)不断增加;复炸时间较短时,产品外壳白度较高,黄度较低;复炸时间过长时,油炸产品外壳红度过高。质构分析显示,随复炸时间的增加,油炸食品外壳的硬度增大,脆性和易碎性得到改善。此外,挂糊油炸猪肉片外壳的含油率与水分含量之间具有负相关关系,相关系数(R2)高达0.981。就色度、含油率和质构而言,在初炸100 s和复炸40-60 s的条件下,制备的挂糊油炸猪肉片外壳具有较高的食用品质。     

以棉籽油为基料油的煎炸专用调和油煎炸品质的研究

以棉籽油为基料油,添加大豆油、菜籽油、棕榈油进行调配,制成煎炸专用的植物调和油。用制得的煎炸调和油进行不间断地煎炸薯条试验,考察煎炸油在煎炸过程中油脂色泽、理化指标及品质的变化情况。结果表明:煎炸调和油的脂肪酸组成合理,满足单不饱和脂肪酸/多不饱和脂肪酸=4.0:0.6的最佳摄入比例。煎炸过程中色泽变化较慢,极性组分超过27%限量的时间为67 h,酸价由(0.18±0.05) mg/g增加至(3.53±0.10) mg/g,羰基价由(9.42±0.12) meq/kg增加至(36.0±0.14) meq/kg,过氧化值和苯并(α)芘没有明显的变化趋势,丙烯酰胺未检出;与河北地区常用于煎炸的三级棉籽油46 h的煎炸寿命和较高的羰基价、过氧化值和苯并(α)芘相比,配制的煎炸调和油的煎炸寿命延长了18 h,稳定性提高了37%,煎炸薯条的平均含油率为18%煎炸感官效果好,可以作为一种新型煎炸调和油。     

油炸过程中淀粉的颗粒形貌、结晶度与热力学特性变化

采用深层油炸模型,利用扫描电镜分析、差示扫描量热分析和x-射线衍射分析等现代仪器分析方法,研究了油炸过程中淀粉的颗粒形貌、结晶结构和热力学性质的变化规律。SEM分析表明,随着油炸温度的增加和时间的延长,淀粉颗粒形态发生了明显变化。在初炸时,淀粉颗粒逐渐膨胀;随着复炸的进行,淀粉颗粒崩解,相互靠近,融合形成大块的团聚体。同时,也导致了淀粉的碘蓝值逐渐减少。DSC测定结果表明,当初炸25 s和50 s时,淀粉分子发生了一定程度的糊化作用;当初炸75 s和100 s时,淀粉完全糊化;当复炸超过20 s时,淀粉在油炸过程中形成了淀粉-脂质复合物。X-射线衍射分析显示,当初炸超过75 s后,淀粉的结晶度均高于初炸25 s淀粉的结晶度;复炸40 s后淀粉的结晶度随油炸时间的延长而降低。