真空法降低油炸制品含油量

以圆柱形土豆条为研究对象,对油炸和冷却过程中样品表面和内部温度、水蒸气压力以及不同阶段吸油量变化规律进行测量与分析,发现油炸过程中由于水蒸气持续从多孔壳层逸出,阻碍了油进入食品中,土豆样品中70%左右油是在冷却阶段进入食品壳层中的,而且导致吸油的动力--蒸汽冷凝形成的壳层内外压差对环境气压很敏感。在油炸样品冷却阶段,将油炸土豆条置于不同真空环境进行冷却,发现绝对压力80kPa的条件下冷却时,总吸油率从40%降至13.6%,说明冷却过程的真空条件能降低壳层内、外压差驱动力,有效促进表面附着油滴落,阻碍其被吸入食品结构中,从而降低油含量。     

精炼淀粉在油炸过程中的含水量、含油量及水分活性之间的相关性研究

为了更好的控制精炼淀粉在油炸过程中含水量、含油量、水分活性的变化以及三者之间的相关性,本实验以精炼淀粉揉成的面团为研究对象,预干燥为前处理手段,考察了含水量、含油量及水分活性在不同预干燥时间和不同油炸时间后的变化。不同预干燥时间的精炼淀粉面团经过不同的油炸时间,样品进行比较分析。结果显示,预干燥能有效减少油炸过程中的水分损失以及吸油量,但是长时间的预干燥会使样品失水过多,从而导致油炸后的样品失去原有的质感。经研究表明,20min的预干燥时间可有效控制水分损失和吸油量。样品油炸时间不宜过长,当油炸至60s时,样品本身的含水量以及含油量基本保持不变。此时,样品含水量为8.55%,含油量为4.81%,水分活性为0.727,吸油量比未经预干燥处理的样品少了57.87%。本研究结果可作为优化油炸调理食品的基础数据和工业化条件的理论依据。     

低脂油炸外裹糊鱼块的制备工艺优化

以外裹糊鲢鱼块为材料,通过研究外裹粉-水质量比（粉水比）、搅拌时间对油炸外裹糊鲢鱼块油脂含量、水分含量、裹糊率的影响及油炸和冷却条件对油炸外裹糊鲢鱼块油脂含量、水分含量、色泽、微观结构和油脂传递的影响,优化制备工艺,减少产品油脂含量。结果显示：粉水比12∶11（g/g）、搅拌时间10 min、170 ℃初炸40 s和190 ℃复炸30 s、30 ℃冷却60 min时,油炸外裹糊鲢鱼块外裹糊和内部鱼块油脂含量分别为19.83%和1.85%。该制备工艺显著减少了油炸外裹糊鲢鱼块的油脂含量,可用于指导规模化生产。     

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。     

裹浆的组成与黏度对裹面包屑罗非鱼片品质影响的研究

以裹粉率、油炸后裹粉鱼片的色度、含油量为指标,结合感官评定,研究了裹浆组成及黏度对裹面包屑罗非鱼片品质的影响。结果表明:裹浆的黏度对产品的裹粉率具有极显著的影响(p 0.01)。通过向裹浆中添加黄原胶、瓜尔豆胶和羟丙基甲基纤维素可以达到与未添加食用胶前裹粉率最大时相同的黏度。油炸后,在裹浆中使用羟丙基甲基纤维素鱼片的L*和b*显著上升(p 0.05),使用三种食用胶的裹浆的含油量降低显著(p 0.05)。在含马铃薯淀粉的小麦面粉中,添加0.47%羟丙基甲基纤维素的裹粉鱼片品质最好。此时鱼片的裹粉率为(44.8±0.9)%,油炸后裹粉层的含油量为(16.4±0.2)%。     

膨化鱼片的热风-微波干燥工艺研究

研究草鱼鱼片的干燥工艺,探讨了热风预脱水鱼片的含水量以及降温、升温和恒温三种预脱水热风干燥模式,微波间歇加热工艺对鱼片品质的影响,并对不同干燥条件下的产品进行了感官、质构和膨化效果分析。结果表明,热风预脱水鱼片含水量控制在35%～50%,选择降温热风干燥模式,微波功率设定中高火档(418±2.5W),加热60s,间歇30s的干燥工艺条件是最佳的。      

添加大豆分离蛋白对油炸面包虾品质的影响

油炸产品通常脂肪含量较高,这会缩短产品的货架期,同时会使得消费者对产品接受度的降低。然而,在油炸过程中,油炸产品的吸油量可以通过裹粉或者裹浆而降低。该研究拟在以小麦粉为主体的裹浆粉中添加大豆分离蛋白,以面包虾的裹粉率、水分损失量、吸油量、色泽、质构以及感官评定等为指标,研究添加大豆分离蛋白对油炸面包虾品质的影响。油炸条件为170℃,油炸3 min。结果表明,大豆分离蛋白显著增加面包虾的裹粉率,且发现它能有效降低油炸面包虾产品的水分损失和吸油量。当大豆分离蛋白的添加量从2 g增大到10 g时,油炸面包虾的水分损失和吸油量分别从15.12%和25.07%降低到11.64%和19.82%。此外,在裹浆中添加8%大豆分离蛋白的面包虾具有最好的质构特性且获得较高的综合感官评分。然而,添加大豆分离蛋白到裹浆中并不会对油炸面包虾的亮度、黄度及红度产生极显著的影响。     

响应面法优化调理鸡排水油混合油炸工艺

为研究调理鸡排水油混合油炸的最佳工艺条件,在单因素试验的基础上,应用响应面法探讨油炸温度和油炸时间及两者交互作用对调理鸡排水分含量,脂肪含量,黄度(b*)值和感官特性的影响,建立了二次响应预测模型。结果表明:水油混合油炸调理鸡排的最佳工艺参数是油炸温度165℃,油炸时间210 s,在此条件下鸡排的含水量为62.41%,脂肪含量为8.98%,黄度(b*)值为51.04,感官评分为8.87,与模型预测值拟合良好。     

膨化鱼片的热风-微波干燥工艺研究

研究草鱼鱼片的干燥工艺,探讨了热风预脱水鱼片的含水量以及降温、升温和恒温三种预脱水热风干燥模式,微波间歇加热工艺对鱼片品质的影响,并对不同干燥条件下的产品进行了感官、质构和膨化效果分析。结果表明,热风预脱水鱼片含水量控制在35%～50%,选择降温热风干燥模式,微波功率设定中高火档(418±2.5W),加热60s,间歇30s的干燥工艺条件是最佳的。     

大豆分离蛋白和油炸条件对面包虾品质的影响

以裹粉率、水分损失率、吸油量、色泽以及质构等为考察指标,研究了油炸温度、油炸时间以及在以小麦粉为主体的裹浆粉中添加大豆分离蛋白对深度油炸面包虾品质的影响。结果表明:大豆分离蛋白能显著增加面包虾的裹粉率(P<0.05),降低油炸产品的水分损失量和吸油量(P<0.01)。在相同的油炸条件下,添加10%大豆分离蛋白的处理组的面包虾的吸油量最低。油炸温度和时间对面包虾的水分损失、吸油量、色泽以及质构产生极显著的影响(P<0.01),随着油炸温度的升高和时间的延长,面包虾的水分损失和吸油量均增加。此外,在170℃条件下油炸4 min,面包虾的脆性最好。     

The effects of industrial pre-frying and domestic cooking methods on the nutritional compositions and fatty acid profiles of two different frozen breaded foods

This study was carried out to determine the effects of manufacturer pre-frying in olive and sunflower oil, as well as domestic cooking methods (deep-frying in olive and sunflower oil and baking) on the proximate compositions and fatty acid profiles of tuna pasties and ham nuggets. The pre-frying processes reduced moisture and carbohydrates and increased ash, fat and protein content in both pre-fried products. During cooking, the frying processes caused a reduction in moisture content and an increase in fat content in relation to pre-fried samples, while baking did not modify the proximate composition. The fatty acid profiles of products during both the pre-frying and frying processes became similar to those of the culinary fat used. Thus, the frying processes reduced the proportion of saturated fatty acids (SFA) and increased the proportion of monounsaturated fatty acids (MUFA) in the foods when olive oil was used, whereas increased the proportion of polyunsaturated fatty acids (PUFA) in products fried in sunflower oil. The fatty acid profiles of fried samples tended to be more similar to the frying fat than to the pre-frying fat, whereas the fatty acid profiles identified during the pre-frying process for baked products were not significantly modified. Thus, samples pre-fried in olive oil and subsequently baked showed the best proportion of fat content and PUFA/SFA, MUFA + PUFA/SFA and n-6/n-3 ratios of the tested products.     

Vacuum frying process of gilthead sea bream (Sparus aurata) fillets

Vacuum frying was tested as an alternative technique to develop low oil content fried gilthead sea bream fillets. Three oil temperatures for vacuum frying (90, 100, and 110 °C) were considered. For each temperature the times investigated were 1, 2, 3, 4, 5, 6, 8 and 10 min. To compare the effect of vacuum frying to atmospheric frying on the characteristics of gilthead sea bream fillets and frying rate, treatment at 165 °C was considered. The effect of oil temperature and pressure conditions on the drying process and oil absorption of sea bream fillets was investigated. Other product attributes such as shrinkage and colour were analyzed. Atmospheric frying (165 °C) produces a greater decrease in the mass of the fillets than vacuum frying treatment. Compared with atmospheric frying, oil content of vacuum-fried fish fillets was lower. After ten minutes of treatment the values obtained for vacuum frying were 0.14 ± 0.01 g_oil/g_{dry solid}, 0.18 ± 0.02 g_oil/g_{dry solid} and 0.12 ± 0.01 g_oil/g_{dry solid} for 90 °C, 100 °C and 110 °C respectively and 0.27 ± 0.01 g_oil/g_{dry solid} for traditional frying at 165 °C. Atmospheric frying was the treatment that produced the greatest shrinkage in the fillets reaching values of 36.8% with respect to the fresh sample after ten minutes of treatment. For vacuum treatments shrinkage values ranged between 23.7% and 33.0% at 100 °C and 110 °C respectively after 10 min of frying. According to the results, the vacuum treated samples became lighter, less greener and more yellow.

Industrial relevance

Healthy products are a tendency in the international market. Vacuum frying offers some advantages that can include: the preservation of natural colour and flavours of the products due to low temperature and low oxygen content during the process (better than with conventional deep fat frying), and has less adverse effects on oil quality. The use of this technology on fish products can improve the problems of market saturation at the present time for some species like gilthead sea bream (Sparus aurata).     

煎炸草鱼鱼块的电导率与品质变化相关性研究

为探究煎炸草鱼鱼块的电导率与品质变化的相关性。利用LCR阻抗测试仪测定100 kHz下煎炸草鱼鱼片的电导率与电流方向的影响研究;测量煎炸过程中草鱼鱼块的水分含量、油含量、色泽与质构等品质变化,并与导电率进行拟合。结果表明,电流方向与鱼体平行时的电导率大于电流方向与鱼体交叉时的电导率(最大差异值为0.15 S/m);鱼片中膜的存在导致不同电流方向上鱼片电导率的不同;随着煎炸时间的增加((180±2)℃,0~4 min),草鱼鱼块的电导率、水分含量、亮度值下降,含油量、红度值和黄度值、硬度和咀嚼性升高;煎炸草鱼鱼块的电导率变化与鱼块的水分含量、油含量、色泽与质构变化均呈一定的相关性,相关系数均大于0.95。电导率测量方法对检测草鱼鱼片煎炸过程中的品质变化具有可行性,为煎炸草鱼鱼片的通电加热等新型加工方法的应用和淡水鱼制品的精深加工等方面提供基础数据和理论依据。      

油炸温度和时间对草鱼鱼片品质影响的研究

本实验以草鱼为研究对象,以油炸后鱼片的水分含量、含油量、色差、质构和感官评定为评价指标,研究了草鱼鱼片在温度为150、170、185℃的大豆油中分别油炸1、2、3、4、5、6min后品质的变化。结果表明:随着油炸时间的延长,油炸温度的升高,鱼片的水分含量降低,含油量升高,颜色加深,硬度和咀嚼性增加,弹性降低;在170℃温度下油炸5min时,鱼片水分含量为50.12%,含油量为13.01%,感官得分最高。      

CHOLESTEROL AND PROXIMATE COMPOSITION OF CHANNEL CATFISH (ICTALURUS PUNCTATUS) FILLETS – CHANGES FOLLOWING COOKING BY MICROWAVE HEATING, DEEP-FAT FRYING, AND OVEN BAKING

Effects of microwave heating, deep-fat frying, and conventional oven baking on proximate composition and concentration of cholesterol in channel catfish fillets were examined. The paired fillet technique was employed to control the variability among fish. A total of fifteen catfish were randomly assigned to the three cooking methods. All cooking procedures resulted in moisture loss. Fillets that were deep-fat fried showed the lowest moisture content but the highest fat content, respectively, among three cooking methods. The three cooking methods, on a dry weight basis, all significantly affected cholesterol concentration of cooked catfish compared with raw fillets. Deep-fat frying resulted in a significant decrease of cholesterol and showed the lowest concentration of cholesterol among three cooking methods probably due to leaching of cholesterol into frying oil.     

油炸温度与时间对白公干鱼传质特性及品质的影响

以白公干鱼为研究对象,探究不同油炸温度(160,180,200℃)和油炸时间(0,20,40,60,80,100,120,150,180s)对白公干鱼水分损失和吸油率的影响,采用特定指数方程对油炸过程中的传质动力学进行曲线拟合;测定油炸后白公干鱼水分活度,建立水分活度与水分含量的关系;测定油炸后白公干鱼色泽、硬度、咀嚼性、表层硬度、韧性,并进行感官品质分析。结果表明:油炸温度的升高可显著增大白公干鱼的水分损失速率和吸油速率,且拟合曲线均符合特定指数方程;白公干鱼水分含量和水分活度呈正相关性,并分为两个区域:水分含量<22%时水分活度随水分含量的增加而快速增大,水分含量>22%时水分活度随水分含量的增加而趋于平缓;结合企业生产经验和感官品质分析,油炸后白公干鱼水分含量控制在22%～26%为宜,达到此水分含量且吸油率最低的加工条件为180℃油炸180s。     

Characterization of crispness of French fries by fracture and acoustic measurements,effect of pre-frying and final frying times

The influence of pre-frying and final frying time on the crispness of French fries was evaluated by simultaneous analysis of the fracture and acoustic properties during instrumental simulation of human chewing. The analysis of the frequency distribution of the force and sound events corresponding to the crust of the French fry reflected an effect of both pre-frying and final frying time on instrumental crispness. Up to 60 s pre-frying, an increase in the number and magnitude of force and sound events was found, which reflect an increase in crispness. The increase in final frying time increased crispness, but it cannot counterbalance a lack of pre-frying. The moisture content of the whole French fries cannot explained the effect of pre-frying on crispness. Conversely, the effect of pre-frying can be explained when considering only the moisture content of the crust. Pre-frying may allow an easier loss of water from the crust during final frying, which will enhance its crispness.     

油炸时间和温度对椰味面包罗非鱼品质的影响

本实验以椰味面包罗非鱼为研究对象,以油炸后产品的水分损失量、吸油量、脆性、色泽和感官评定为指标,分别考察油炸时间为1.5、2.5、3.5、4.5 min以及油炸温度为160、170、180、200℃对椰味面包罗非鱼品质的影响;并通过低场核磁共振初步探究油炸过程中水分损失量和吸油量的关系。结果表明:随着油炸时间的延长和油炸温度的升高,面包鱼的水分损失量增大,吸油量增多,呈现正相关关系;且最佳的油炸条件为170℃油炸2.5 min,此条件下得到的面包鱼色泽金黄、外酥里嫩,感官评定的分数最高。      

EFFECTS OF COOKING CONDITIONS AND POST-PREPARATION PROCEDURES ON THE QUALITY OF BATTERED FISH PORTIONS

The effects of different cooking conditions and postpreparation handling on quality of battered fish portions for fast food services were investigated. As the frying temperature increased from 300 to 400°F (149–204°C), the cooking time of battered fish portions decreased from 276 to 202 s. Crude lipid content in the batter decreased as the temperature of the frying oil increased. Holding times (10, 20 min) affected crude lipid contents of the batter depending on the cooking temperature and were lower than an unheld product. Crude lipid contents in the fish fillets were generally higher after frying by 2–3%. The crude lipid uptake by the batter coating differed significantly for the three frying shortenings (partially hydrogenated soybean, V-S oil; animal fat-vegetable blend, A-V Fat; and vegetable-palm oil blend, V-P oil;) compared in this study. This finding contrasts with previously published results. The amount of crude lipid uptake by the fish varied with shortening type and holding times. No consistent trend was observed to occur. Peroxide values increased after 3 days in the V-S Oil and A-V Fat. Flavor scores on battered fish portions cooked in V-S Oil, V-P Oil, and A-V Fat were not statistically different immediately after cooking and after holding for 10- +20-min on the first day. By the second day, differences were observed among the three shortenings. Both shortening type and postpreparation holding times affected the perceived greasiness.