油炸时间和温度对模拟马铃薯片油脂吸收的影响

为了研究油炸时间与温度对油炸样品的油脂吸收的影响,以马铃薯淀粉和水为原料,配制出模拟马铃薯片,以此简单体系为研究对象,采用染色油的方法来测定不同分布的油脂含量,从而得出表面油脂、表面渗透油脂、结构油脂、总油脂的含量。结果表明,样品总油脂和结构油脂含量随着油炸时间的增加而增加,表面渗透油脂含量随着时间的增加先上升后下降,而油炸时间对表面油脂的含量影响不显著。随着油炸温度的上升,总油脂含量显著增加,结构油脂含量呈现上升趋势;在180℃和200℃下,表面油脂含量之间没有显著性差异;140℃和其他温度下的表面渗透油脂含量存在显著差异。      

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.     

Oil Uptake in Deep Fat Frying as Affected by Porosity

The porosity of a restructured potato product ranged from 0.089 to 0.168 after fluctuating subfreezing storage temperatures. A linear relation was found between oil uptake during frying and porosity prior to frying. Bulk and particle density, and porosity were monitored for up to 5 min during deep-fat frying. Particle density increased gradually, bulk density decreased and porosity increased noticeably. After an initial short period, oil uptake correlated linearly with porosity of the fried product. A new term, “net porosity” which excluded the void volume occupied by oil was developed for describing the oil uptake mechanism.     

Relationship between oil uptake and moisture loss during frying of potato slices from c. v. Record U.K. tubers

The variations in moisture content and oil content of samples of 1.5-mm thick slices of potato (c.v. Record U.K.) were examined after various frying times at frying temperatures of 145, 165 and 185°C. The loss of moisture and the uptake of oil were found to be interrelated and both were linear functions of the square root of frying time. Within the temperature range examined, moisture loss and oil uptake were found to be independent of frying temperature. From the data and visual observations the mechanism of moisture loss and its influence on oil content in the final product were discussed. Suggestions are made for means of reducing the total oil content by modifications in the frying process.     

Effect of pre-fry drying of oil uptake and distribution in potato crisp manufacture

Microwave, hot air (40 and 105°C) and freeze drying were used to remove varying amounts of moisture from 1.3 mm thick potato slices. The partially dried slices were then fried in oil at 165°C either for a constant 2 min or a variable frying time based on the amount of pre-drying. The microwave and hot air treatments resulted in a reduction in the final oil content, which was related to the degree of pre-fry drying. Freeze drying resulted in an increase in the oil content, again related to the initial moisture reduction. Oil distribution at the microscopic and macroscopic level was determined and found to be related to the initial moisture distribution in the slice. It is suggested that pre-fry drying may be a more successful point of influence than post-fry treatment in the manufacture of a'lower fat crisp'.     

非油炸甘薯脆片的工艺研究

研究了非油炸甘薯脆片加工过程中 ,薯团水分含量、食用油、淀粉添加量、薯片烘烤温度、膨松剂对甘薯脆片成品品质的影响。结果表明 ,薯团水分含量为 49%～ 50 % ,油添加量为 6% ,薯团辊扎成型质量较好 ;添加 5‰NH4 HCO3或 5‰的 NH4 HCO3与 Na HCO3的复合膨松剂 ,于 1 30℃烘烤 9min,可获得水分含量 3.5% ,脂肪含量7.7% ,色泽金黄 ,外观平整 ,松脆适中 ,有甘薯香味 ,无异味的甘薯脆片。     

薯片在油炸过程中品质变化及其货架期预测

为了探究薯片在油炸过程中品质变化,以不同油炸时间马铃薯片为研究对象,测定马铃薯片的品质变化,观察其微观结构并对马铃薯片货架期进行预测。结果表明:随油炸时间的延长,马铃薯片的水分含量降低,含油率升高,脆度变化较大;马铃薯片表面淀粉颗粒糊化逐渐形成凸起和空隙,由于外皮壳的保护作用,空隙先在横断面中出现,薯片内部空隙多于其表面;通过比较脱脂前后薯片,表明薯片与煎炸油之间以物理作用为主;随着薯片贮藏时间的延长,薯片中油脂的酸值、过氧化值和羰基值逐渐增大,根据Arrhenius方程预测薯片在20℃的货架期约为102d。     

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。     

常压油炸马铃薯脆片加工工艺参数的研究

以适于油炸加工的马铃薯品种--大西洋为原料,研究了切片厚度、坯料烘干时间(含水量)、被膜剂浓度、油炸时间、油炸温度对常压油炸马铃薯脆片品质的影响,确定了常压油炸马铃薯脆片的加工工艺参数,即马铃薯切片厚度为2.0mm,油炸坯料于50℃温度下烘80min,含水量控制在60%左右,油炸前用0.8%的CMC-Na溶液被膜,在180℃油温下炸制2min。     

油脂饱和度对油炸马铃薯片品质的影响

以玉米油、花生油、大豆油、大豆棕榈调和油、棕榈油5种不同饱和度油脂作为煎炸用油,以马铃薯片为煎炸内容物,于140℃循环煎炸。考察马铃薯片的油脂含量、水分含量、色泽、酥脆性以及感官评分的变化,综合分析油脂饱和度对油炸马铃薯片品质的影响。结果表明:煎炸油脂的饱和度显著影响油炸马铃薯片的品质(p 0.05),随着煎炸油脂饱和度的增加,油炸马铃薯片的油脂含量呈降低的趋势,水分含量呈增加的趋势,L值呈增大的趋势,表明马铃薯片颜色随着煎炸油脂饱和度的增加而越发鲜亮;油炸马铃薯片的酥脆性、感官评分亦随煎炸油脂饱和度的增加呈显著增加的趋势(p 0.05)。由此可知,相对于不饱和度较高的玉米油、花生油、大豆油,饱和度较高的棕榈油更加适合马铃薯片的煎炸。     

稻米油调和油煎炸应用研究

通过与棕榈油对比180℃下炸制薯片以及评估薯片感官喜好度、质构、口感及粘牙性等差异来评价稻米油调和油的煎炸应用性能。结果表明:采用稻米油调和油煎炸的薯片中多不饱和脂肪酸含量显著高于棕榈油(P<0.05),且其薯片的整体感官喜好度、质构口感、酥脆度、粘牙喜好度,均显著优于棕榈油薯片(P<0.05)。在加速氧化条件下,采用稻米油调和油炸制的薯片的酸价、过氧化值均与棕榈油炸制的薯片无显著性差异(P>0.05),且远低于GB 16565-2003的规定。在加速存储过程中,谷维素却得到了很好的保留。总之,稻米油调和油具有良好的煎炸性能。     

Modeling water loss and oil uptake during vacuum frying of pre-treated potato slices

The objective of this research was to determine the kinetics of water loss and oil uptake during frying of pre-treated potato slices under vacuum and atmospheric pressure. Potato slices (diameter: 30 mm; width: 3 mm) were pre-treated in the following ways: (i) raw potato slices “control”; (ii) control slices were blanched in hot water at 85 °C for 3.5 min; (iii) blanched slices were dried in hot air until reaching a moisture content of ∼0.6 g water/g dry basis. The slices were fried under vacuum (5.37 kPa, absolute pressure, at 120, 130 and 140 °C) and atmospheric conditions (at 180 °C). Two models based on the Fick's law were used to describe water loss: (i) with a constant effective diffusive coefficient; and (ii) with a variable effective diffusive coefficient. Oil uptake data were fitted to an empirical model, with a linear behavior for short times whereas the model was time independent for long times. The variable diffusivity model better fitted experimental water loss, giving values of effective diffusivity between 4.73 × 10⁻⁹ and 1.80 × 10⁻⁸ m²/s. The proposed model for the study of the kinetics of oil uptake fitted the experimental data properly. Control and blanched vacuum fried potato chips increased their final oil contents to 57.1% and 75.4% respectively, when compared with those fried at atmospheric pressure. However, the oil absorption of dried vacuum fried potato chips diminished by ∼30%.