预处理工艺对真空油炸脱水马铃薯脆片品质的影响

通过热烫、冷冻、渗透液处理等预处理技术对真空油炸马铃薯脆片品质影响作了比较;综合各指标分析,得出了马铃薯脆片真空油炸的较佳预处理工艺。实验结果表明,冷冻参数对油炸马铃薯脆片水分质量分数不存在主要影响,热烫温度是主要影响因素;渗透组的马铃薯脆片,随着渗透浓度的增加,其水分质量分数逐渐减少。冷冻参数对油炸马铃薯脆片脂肪质量分数影响也不大;热烫时间较短的马铃薯脆片油炸后脂肪质量分数较高,热烫时间较长的马铃薯脆片油炸后脂肪质量分数较低。热烫温度75℃、时间6min的脂肪质量分数最低;渗透浓度越高,马铃薯脆片油炸后脂肪质量分数越低。     

蚕豆真空油炸试验研究

以慈溪所产大白蚕豆为原料，研究了浸渍、冷冻以及热风干燥对真空油炸脆蚕豆品质的影响。结果表明：浸渍、冷冻以及热风干燥显著影响脆蚕豆的水分含量和含油率，且蚕豆初始水分含量与其含油率之间存在显著的相关性。浸渍和热风干燥预处理技术可以显著降低产品的含油率，而且不影响其脆度和主要色泽值。     

胡萝卜真空油炸脱水工艺和优化研究

研究了不同预处理条件哒展油炸温度、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、真空度以及时间显著影响胡萝卜片中水分与脂肪含量以及脆度（P≤0．05）;其最佳油炸工艺为温度100℃-110℃、真空度0．08—0．09MPa、时间15min。     

多孔粒状铵油炸药水分与组份测定

为了研究多孔粒状铵油炸药的组成成份及各组份所占的百分比，本文采用水浴烘箱法和水分测定器法测得多孔粒状铵油炸药的水分含量，同时采用蒸馏洗涤方法测量分析多孔粒状铵油炸药中硝酸铵与柴油所占比例。实验结果表明：使用水分测定器法测得多孔粒状铵油炸药的水分含量更为精确，水分测定器法适用于含有柴油类的铵油炸药。蒸馏洗涤方法测量多孔粒状铵油炸药的组份方便可靠。     

脱水莴苣片的护色工艺研究

针对脱水莴苣片在贮藏过程中的变色问题进行研究,寻找出有效的护色方法。首先。通过研究最佳的热烫条件,保证酶活对颜色没有影响,并尽量减少热烫对颜色的损失,选择出最佳的热烫条件为95℃、4min。然后,采用各种护色方法进行试验,最终得出了糖和盐的渗透处理是最好的护色方法。并研究了渗透处理对莴苣片的其他影响,得出渗透处理不但提高了色素的稳定性,而且降低了水分活度。增加了产品的得率,提高了复水速率。     

超声雾化喷涂保色牡丹花冻干试验研究

将保色溶液超声雾化并对牡丹花进行喷涂护色处理,对处理过的牡丹花进行真空冷冻干燥,研究了保色溶液组成、雾化喷涂时间等指标对干花品质的影响。结果表明：超声雾化喷涂保色液具有明显的保色、保形作用,冷冻干燥后牡丹干花的颜色和形状保持得很好。     

简述PET聚酯切片水分的测试

聚酯切片含水量是衡量切片品质的一项重要指标,因此对于测试切片水分含量影响因素的研究十分必要。本文通过比较存放时间及不同测试方法对PET聚酯切片含水量的影响,发现存放时间与切片水分含量成正比,使用真空烘箱法与电热鼓风干燥箱法对测试结果无显著性差异,使用卤素水分仪测试切片水分结果比重量法平均高出0.02%左右。     

胡萝卜片真空油炸过程用油品质研究

主要探讨了真空油炸胡萝卜片后三种炸用油的稳定性，研究了三种炸用油的酸价、过氧化值、羰基价随油炸时间的变化规律，分析了它们之间的相关性。结果显示：与大豆色拉油相比，棕榈油和猪油有更高的油炸稳定性；三种油的酸价、过氧化值、羰基价与油炸时间存在着显著的相关性。     

新型颗粒胶干燥设备

一、前言紫胶加工的中间产品——颗粒胶,无论是作为商品销售或再加工,对其水分含量均有一定要求。溶剂法和间接蒸汽热滤法制片胶中粒胶水分要控制在3～6％以下,否则影响产品水分含量及回收酒精浓度。销售及贮存的粒胶水分含量要≤2.5％,以免结块发酵或聚合变质。目前在工厂经洗色、离心脱水后的粒胶水分含量仍在10％左右,故还需进一步干燥处理。     

半干罗非鱼片加工工艺研究

以新鲜罗非鱼为原料，经去内脏去皮取片、腌制调理和干制等处理，制成半干罗非鱼片。同时，就其加工过程中水分含量变化、不同干燥温度的干燥曲线和不同盐分与水分活度剂对成品色泽、水分活度和状态等的影响进行较为系统的研究。以期找出半干淡水鱼片的较佳加工工艺技术。     

Effect of Vacuum-Microwave Predrying on Quality of Vacuum-Fried Potato Chips

The effects of vacuum microwave predrying on the quality of vacuum-fried potato chips were studied. The results showed that vacuum microwave predrying had a significant effect on moisture and oil contents, as well as color parameters and structure of potato chips. Vacuum microwave predrying significantly decreased the oil and moisture contents of vacuum-fried potato chips. The rates of both mass transfer phenomena (water loss and oil uptake) that take place during the vacuum frying of potato chips decrease due to the vacuum microwave predrying. The vacuum microwave predrying had a negative effect on color of potato chips, which decreases the L value of potato chips and increases Hunter a and b values. Breaking force of fried potato chips is also significantly (P < 0.05) affected by the drying pretreatment, which decreases the breaking force at the beginning of predrying and then increases with vacuum microwave predrying time.     

Optimization of Vacuum Microwave Predrying and Vacuum Frying Conditions to Produce Fried Potato Chips

The effects of vacuum microwave predrying and vacuum frying conditions on the quality of vacuum-fried potato chips were studied. Both the moisture content and oil content of potato chips decreased with increasing vacuum microwave predrying time. During vacuum frying, the moisture content of potato chips decreased with increasing frying temperature and time, while the oil content increased. Statistical analysis with response surface regression showed that the moisture content, oil content, and breaking force of potato chips were significantly (P<0.05) correlated with vacuum microwave predrying time, frying temperature, and frying time. Based on surface responses and contour plots, optimum conditions were vacuum microwave predrying time of 8–9 min, vacuum frying temperature of 108–110°C, and vacuum frying time of 20–21 min.     

Lipid oxidation in potato chips

Qualitative and quantitative analyses of volatile compounds in fresh and aged potato chips and unused fresh and aged frying oils showed that oxidation of oils was mainly responsible for volatile compound changes in potato chips during storage. The lipid oxidation of potato chips was determined by measuring the peroxide value of potato chips and the amount of volatile compounds and oxygen content in the headspace of potato chip bottles by gas chromatography. The correlation coefficients between volatile compounds and oxygen content, volatile compounds and peroxide value, and peroxide values and oxygen content were -0.93, 0.95 and -0.93, respectively. These high correlation coefficients indicated that volatile compound changes in potato chips during storage were mainly due to the oxidation of oil. The lipid oxidation of potato chips during storage can be studied by measuring oxygen content and the amount of volatile flavor compounds in the headspace. The potato chips produced in oil containing an antioxidant tertiarybutyl hydroquinone (TBHQ) had better oxidation stability than the chips fried in oil without TBHQ.     

Composition of oils extracted from potato chips by supercritical fluid extraction

To determine effects of two extraction procedures on oil compositions, tocopherols, monoacylglycerol, diacylglycerol, triacylglycerol, free fatty acids, polymers and polar components were determined in oils after extraction from potato chips by either supercritical carbon dioxide or hexane. Potato chips were fried in cottonseed oil or low linolenic acid soybean oil and sampled after 1, 10 and 20 h of oil use. Both extraction methods recovered comparable amounts of oil from the potato chips. Compositions of triacylglycerol and non‐triacylglycerol components including tocopherols, monomer, polymer, monoacylglycerol, diacylglycerol were similar for samples of chips fried in either oil except for the δ‐tocopherol data for potato chips fried in the low linolenic acid soybean oil used for 10 h of frying. There were some differences between the composition of low linolenic acid soybean oil extracted from the potato chips compared to the fryer oil at the 20 h sampling time. These results showed that the supercritical carbon dioxide extraction gave similar results to hexane extraction in yield and composition of oils from potato chips.     

Low oil content potato chips produced by infrared vacuum pre-drying and microwave-assisted vacuum frying

The effects of vacuum infrared radiation (VIR) pre-drying on the microwave-assisted vacuum frying (MVF) potato chips were investigated to study its possibility of decreasing the oil content of fried potato chips. The moisture evaporation, oil content, texture, color, surface temperature, shrinkage, and sensory analysis of fried products were evaluated. Results showed that the VIR pre-drying significantly reduced the oil content in MVF products, a decrease from 22.38 to 13.49?g oil/100?g dry solid. The application of VIR pre-drying accelerated the dehydration rate, and increased the mechanical breaking force measured with a texture analyzer with 20–30?min pre-drying. The VIR pre-drying resulted in an increase in the total color change and the shrinkage of MVF potato chips. The sensory analysis showed that the proper duration of VIR pre-drying would achieve a higher consumers’ acceptance. Comparing with the current industrial applications, vacuum frying, and atmospheric deep-fat frying, the combined VIR and MVF technology would be an alternative frying method for producing healthier fried products with less oil content and high quality.     

Antioxidative effect of olive oil deodorizer distillate on frying oil and quality of potato chips

The antioxidative effect of unsaponifiable matter from olive oil deodorizer distillate on the stability of sunflower oil during frying and on the quality of potato chips were studied. Physical and chemical characteristics of sunflower oil samples with or without different concentrations of unsaponifiable matter were examined during frying at 180°C for ten consecutive days. The addition of 1% of unsaponifiable matter to sunflower oil showed the highest effect in retarding the oxidation deterioration of oil during frying of potato chips. This protective effect was attributed to high levels of squalene, Δ-avenasterol, and tocopherols. During ten frying days, the amount of squalene decreased to 79% and both tocopherols and Δ-avenasterol to 69% in frying sunflower oil. Oil absorbed by potato chips and the characteristics of the oil extracted from potato chips before and after three months of storage were determined. The amount of oil absorbed by potato chips ranged from 37.3 to 39.3% during frying. The unsaponifiable fractions remaining in the frying medium showed protective effects on the rate of oxidation of the oil extracted from potato chips. The uptake of unsaponifiable matter by chips was the highest during the first frying day. Chips with high amounts of squalene, tocopherols, and sterols showed highest antioxidative stability during storage for three months at ambient temperature. Potato chips fried in sunflower oil treated with 1% unsaponifiable matter showed a bright yellow colour, moderate crispness, high score flavour, and were well accepted by panelists. These data of sensory evaluation supported the results of chemical analyses of oil extracted from fresh and stored chips.     

Effect of low temperature on the microwave-assisted vacuum frying of potato chips

The objective of this study was to investigate the effect of low temperature on the microwave-assisted vacuum frying of potato chips. A newly built, in-house, microwave-assisted frying machine was developed and used in this study. The effect of low temperature on the microwave-assisted vacuum frying of potato chips was investigated via comparing sample properties prepared with frying temperatures of 90°C, 95°C, and 100°C. The experience was taken at the same vacuum degree in every frying process. Parameters of included moisture content, oil content, color parameters (lightness, redness, and yellowness), and textures (hardness, crispness) were used to evaluate the effect of different frying temperatures on the microwave-assisted vacuum frying of potato chips. Results showed that with lower temperature in microwave-assisted frying, the rate of moisture evaporation of potato chips was slowed down and the time of the ending of frying was prolonged from 10 min with a frying temperature of 100°C to 14 min with 90°C and 12 min with 95°C. Meanwhile, the oil content in fried potato chips was increased with lower temperature in microwave-assisted vacuum frying. The breaking force of final products are not significantly (p > 0.05) affected in different frying temperatures of microwave-assisted vacuum frying. Also, the frying temperature of 100°C in microwave-assisted vacuum frying had better preservation of natural color than the lower frying temperature with prolonged frying time. Results showed that the temperature is one of the main factors that affect the quality of microwave-assisted vacuum frying of potato chips and the producer could find suitable temperature conditions according to experience.     

Frying quality and stability of low-and ultra-low-linolenic acid soybean oils

To determine effects of very low levels of linolenic acid on frying stabilities of soybean oils, tests were conducted with 2% (low) linolenic acid soybean oil (LLSBO) and 0.8% (ultra-low) linolenic acid soybean oil (ULLSBO) in comparison with cottonseed oil (CSO). Potato chips were fried in the oils for a total of 25 h of oil use. No significant differences were found for either total polar compounds or FFA between samples of LLSBO and ULLSBO; however, CSO had significantly higher percentage of polar compounds and FFA than the soybean oils at all sampling times. Flavor evaluations of fresh and aged (1, 3, 5, and 7 wk at 25°C) potato chips showed some differences between potato chips fried in different oil types. Sensory panel judges reported that potato chips fried in ULLSBO and aged for 3 or 7 wk at 25°C had significantly lower intensities of fishy flavor than did potato chips fried in LLSBO with the same conditions. Potato chips fried in ULLSBO that had been used for 5 h and then aged 7 wk at 25°C had significantly better quality than did potato chips fried 5 h in LLSBO and aged under the same conditions. Hexanal was significantly higher in the 5-h LLSBO sample than in potato chips fried 5 h in ULLSBO. The decrease in linolenic acid from 2 to 0.8% in the oils improved flavor quality and oxidative stability of some of the potato chip samples.     

Effects of natural and synthetic antioxidants on changes in refined, bleached, and deodorized palm olein during deep-fat frying of potato chips

The effects of antioxidants on the changes in quality characteristics of refined, bleached, and deodorized (RBD) palm olein during deep-fat frying (at 180°C) of potato chips for 3.5 h/d for seven consecutive days in five systems were compared in this study. The systems were RBD palm olein without antioxidant (control), with 200 ppm butylated hydroxytoluene (BHT), 200 ppm butylated hydroxyanisole (BHA), 200 ppm oleoresin rosemary, and 200 ppm sage extract. Fried oil samples were analyzed for peroxide value (PV), thiobarbituric acid (TBA) value, iodine value (IV), free fatty acid (FFA) content, polymer content, viscosity, E^1% _{1 cm} at 232 and 268 nm, color, fatty acid composition, and C_18:2/C_16:0 ratio. Sensory quality of the potato chips fried in these systems prior to storage was also evaluated. The storage stability of fried potato chips for 14 wk at ambient temperature was also determined by means of the TBA values and sensory evaluation for rancid odor. Generally, in the oil, oleoresin rosemary gave the lowest rate of increase of TBA value, polymer content, viscosity, E^1% _{1 cm} at 232 and 268 nm compared to control and three other antioxidants. The order of effectiveness (P<0.05) in inhibiting oil oxidation in RBD palm olein was oleoresin rosemary > BHA > sage extract > BHT > control. Prior to storage, the sensory evaluation of fried potato chips for each system showed that there was no significant (P>0.05) difference in terms of flavor, odor, texture, and overall acceptability. The same order of effectiveness (P<0.05) of antioxidants was observed for storage stability study of fried potato chips by TBA values. However, there was no significant (P > 0.05) difference in sensory evaluation for rancid odor during storage periods.