Vitamin C Retention of Potato Fries Blanched in Water

Vitamin C retention was determined microfluorometrically for French fries heated in water. Vitamin C retention for 1.3 cm (½ in.) water blanched French fries ranged from 83.2–54.1%. The French fry blanch times were 5, 10 and 15 min at 66°C, 77°C and 88°C. The apparent Ea was 4.0 Kcal/mole.     

Effect of Surface Freezing on Ascorbic Acid Retention in Water Blanched Potato Strips

The average retention of ascorbic acid in potato strips (10 × 10 × 80 mm) blanched in water at 50°C and 65°C over various blanching times, with and without surface freezing pre-treatment was determined. The strips were frozen in Freon Freezant-12 for 15 sec, with the freezing front penetrating 0.4–0.5 mm. Average retention of ascorbic acid in the surface-frozen potato strips was significantly lower than that in fresh strips and lower at 65°C than at 50°C. At an equal average retention of ascorbic acid, at 50°C the fresh strips required a blanching time four times higher than that for the surface-frozen strips; at 65°C it was twice as high.     

蔬菜维生素C保留因子的研究

目的:通过比较不同蔬菜、不同烹调方法间维生素C保留因子(RF)的差异,探讨影响蔬菜维生素C保留因子的因素。方法:选取常见的12种蔬菜,以炒、炖、炸、蒸、焯、盐腌的方法进行烹调,分别记录烹调前后蔬菜的质量。采用GB/T5009.86-2003荧光法测定蔬菜烹调前后维生素C的含量,计算相应的质量保留因子(保留率)和维生素C保留因子(保留率)。结果:鲜豆类蔬菜,焯和炖的维生素CRF>75,两种腌制菜肴的维生素C保留率仅为5%。根茎类蔬菜的情况比较复杂,缺乏规律性。叶菜类蔬菜,炒较之焯更利于维生素C的保留,RF值在80左右。炒对于茄果类蔬菜不会造成维生素C损失较大,RF>70。结论:炸、盐腌、蒸的烹调方法使维生素C损失较大,炒的烹调方法的维生素C保留率较高;温度、时间、蔬菜的品种是影响维生素保留因子的重要因素。     

不同贮藏方式对土豆中VC含量的影响

以探讨不同贮藏方式对土豆中VC含量的影响为目的;采用2,6-二氯靛酚滴定法测定不同贮藏方式下的土豆中VC的含量变化;结果是三种贮藏方式下的土豆中VC的含量随着贮藏时间增加而降低,常温贮藏比低温贮藏的土豆VC含量和保存率较高,连续干燥比间歇干燥时维生素保存率高。     

Textural Characterization and Kinetics of Potato Strips During Frying

ABSTRACT: A single puncture test (SPT) system was designed to determine textural changes in potato strips in situduring frying at 160, 175, and 190 °C. Puncture force changed drastically with time and depth in the strip during frying. Force-distance curves were expressed as representative textural parameters as CF (core force), RF (rupture force), and S (springiness). Normalized parameters CF* and S* for core force and springiness were used in modeling textural changes in the core during initial tissue softening and later crust development process, respectively. High frying temperatures accelerated the process, and the finished fried potato strip was a composite structure made of a hard crust and a soft core.     

Application of Low-Field NMR to Analyze Water Characteristics and Predict Unfrozen Water in Blanched Sweet Corn

Water characteristics and prediction of unfrozen water in sweet corn treated with different blanching temperatures (20, 40, 50, 60, 70, 80, 90, and 100 °C/10 min) were investigated by low-field nuclear magnetic resonance (LF-NMR). Transverse relaxation analysis was firstly used to study the changes of water characteristics and distribution. Then, a chemometric method using partial least squares (PLS) method was employed to predict unfrozen water. Four relaxation components were discerned and pertained to vacuolar, cytoplasmic, and extracellular water, and cell wall protons, respectively. The intracellular water in sweet corn was transported to extracellular space after treatment and the loss of intracellular water increased with blanching temperature. Three groups of blanching temperatures were discriminated by principal component analysis. The PLS regression model based on LF-NMR data accurately predicted unfrozen water in blanched sweet corn with an adjusted determination coefficient of 0.97.     

响应面优化速冻马铃薯条的护色工艺

马铃薯在加工过程中极易发生褐变,严重影响速冻马铃薯条的产品品质。研究了不同单一护色剂对多酚氧化酶的抑制作用,通过多种护色剂复配对马铃薯进行护色实验。结果表明,抗坏血酸,柠檬酸,氯化钙对PPO酶活性均表现出一定的抑制效果,其最佳质量分数分别为0．20％,0．40％,0．70％;经响应面优化,得出三种护色剂最佳的复配质量分数为抗坏血酸0．30％,柠檬酸0．50％,氯化钙0．76％,此时马铃薯条表面的褐变基本被抑制。     

不同焙烤条件的烤马铃薯条品质对比

为了探究烤马铃薯条的焙烤工艺,对比分析了不同焙烤温度和时间组合下,马铃薯条的水分含量、水分状态、抗氧化性、总酚含量、风味物质、色度及质构特性的变化规律。结果表明,随着焙烤温度的升高和焙烤时间的缩短,烤马铃薯条的水分流动性和水分含量均呈现降低的趋势,硬度和咀嚼度呈现先下降后上升趋势,抗氧化性和总酚含量呈现上升的趋势;烤马铃薯条色泽逐渐加深。不同的焙烤条件组合对烤马铃薯条主要风味物质种类的影响不显著,但对风味物质含量的影响较为明显。其中160℃烤25 min条件下,马铃薯条硬度为1532.14 g;而DPPH自由基清除率为85.25%,总酚含量为279.18 mg/100 g,相对较高;且香味明显,色泽鲜亮,是比较合适的焙烤条件。该研究可为马铃薯在食用或加工中选择适宜的焙烤条件提供理论参考。     

甘薯嫩叶中Vc在加工过程的变化

采用2,4- 二硝基苯肼比色法测定甘薯嫩叶中VC 含量,分析不同贮藏条件及干制、腌制、速冻、烹饪等不同加工方式对VC 含量的影响。结果表明：甘薯嫩茎叶中VC 含量高达26.48mg/100g;甘薯嫩叶采后营养价值随存放时间而递减,低温冷藏和冷冻均能降低其营养损失速度,在6℃下贮藏9d VC 含量为15.96mg/100g;干制及腌制对VC 有较大的损害。甘薯嫩叶的烹饪以适当的高温及尽可能短的时间为佳,在160℃、50s 下VC 残留含量为16.85mg/100g。烹饪过程中适当添加调味料如食醋和蔗糖,可以减少VC 的损失。     

阳离子马铃薯渣助留体系在废纸浆中的应用

研究了阳离子马铃薯渣单元、二元、三元助留助滤体系在废纸浆中的应用,并考察了PAC用量、电导率、pH值对PAC-阳离子马铃薯渣-APAM三元体系的助留助滤效果的影响.结果表明,三元体系较单元和二元体系助留助滤效果好.当PAC用量为1.5%、阳离子马铃薯渣用量为1.5%、APAM加入量0.1%时,三元体系对废纸浆的助留助滤效果最好,首程留着率可达90.1%;滤水量可达918 g/20s.     

Vitamin C Stability during Preparation and Storage of Potato Flakes and Reconstituted Mashed Potatoes

High performance liquid chromatography with electrochemical detection was used to follow losses of L-ascorbic acid (AsA) in the processing and serving of fortified mashed potatoes. Cumulative losses of AsA were: 56% for adding AsA to freshly mashed potatoes at 251 ppm (wet basis); 82% drum-drying the potatoes; 82% storing the flakes 4.3 months at 25°C., and 96% reconstituting mashed potatoes and holding them 30 min on a steam table. The mashed potatoes at the point of ingestion would contain 10 ppm AsA (wet basis), and one serving size (100g) would provide 2% of the adult RDA. Fortification with equivalent levels of magnesium L-ascorbate 2-mono-phosphate (AsMP) or sodium L-ascorbate 2-polyphosphate (AsPP) gave overall cumulative losses of 20 or 32%, respectively. Such reconstituted mashed potatoes contained 201 ppm and 171 ppm AsA respectively, and one serving would provide about 33% of the RDA of vitamin C.     

酶法改性大豆分离蛋白涂膜对油炸薯条吸油率的影响

大豆分离蛋白涂膜具有较好的控油效果,在油炸过程中既能减少食品组织中的水分散出,又要能有效地阻止油脂渗入食品。文中研究了谷氨酰胺转胺酶（TG）改性大豆分离蛋白对于油炸薯条品质的影响。研究表明,适当的改性条件可以降低薯条的吸油率。     

Consumer Acceptability and Quality Evaluation of Potato Strips Baked in a Radiant Wall Oven

Instrumental and sensory quality of potato strips baked in a radiant wall oven was evaluated and compared to deep-fat fried and conventional oven baked samples. Even though radiant wall oven baked potato strips had one-fourth the fat content of the deep-fat fried samples, there was no significant difference in chroma, cutting and puncture force of radiant wall oven baked and deep-fat fried samples. Consumer acceptability of radiant wall oven baked potato strips was 65.7 and 85.7% before and after revealing the nutrition facts, respectively. Both were lower than acceptability of deep-fat fried samples. However, 36.5% of consumers were willing to purchase radiant wall oven baked samples.     

On Water in Potato Starch

Thermal analysis (TG and DTA) was carried out on potato starch dried in the air at room temperature as well as at 130°C, and also on that dried azeotropically with benzene. Water present in the matrix of potato starch influences the whole pathway of dextrinization up to at least 300°C. The mode of removal of water from air-dried starch also subtly changes the route of thermal decomposition of starch and magnitudes of thermal effects. The role of atmospheric oxygen in thermolysis is also documented.     

测定涂料保水值的新方法

此文旨在阐明不同保水测试结果的意义和提高对涂料脱水机理的认识。为了阐明颜料等级对保水的影响，对不同颜料混合物进行了研究。选择颜料混合物以说明不同的表面结构和大范围的粒度分布。对一般的预涂和面涂综合使用了两种主要的涂料颜料———碳酸钙和瓷土。采用不同类型的复合胶粘剂以获得对其保水体系及其对流变性影响的认识。为了将其他化学品的影响降至最小，此研究未对胶粘剂或润滑剂的用量进行优化。采用毛细管流变图作为最后涂料制备的依据，通过复合胶粘剂用量调节涂料在５０００００L／s下的粘度到一恒定的水平。在相同的粘度…     

Characterization of Aroma-Active Compounds in Microwave Blanched Peanuts

ABSTRACT:  Microwave blanching of peanuts has been explored as an alternative to conventional oven methods based on its speed of operation, energy savings, and efficiency of process control. Although processing times can be greatly reduced, the occurrence of stale/floral and ashy off-flavors has been reported at high process temperatures. This study examined the chemical compounds responsible for this off-flavor using solvent extraction/solvent assisted flavor evaporation (SAFE), gas chromatography-olfactometry (GC/O), gas chromatography-mass spectrometry (GC/MS), and aroma extract dilution analysis (AEDA). Select compounds were quantified based on AEDA results using SAFE and GC/MS. Quantification, threshold testing, and analysis of model systems revealed increased formation of guaiacol and phenylacetaldehyde in the off-flavored peanuts, which resulted in the burnt and stale/floral flavors noted by a trained panel.     

Combined Effects of Gamma Irradiation and Blanching Process on Acrylamide Content in Fried Potato Strips

Potato tubers were irradiated in ⁶⁰Co gamma station at different doses in order to investigate the effect of gamma irradiation on acrylamide formation in fried potato strips. Acrylamide content due to the irradiation treatment was reduced by 20–54% compared to a control after frying the irradiated tubers. While apply a blanching process, using warm tap water, to potato strips before frying has decreased acrylamide by 61%. A combination of gamma irradiation and a blanching process, which was applied in this work, showed a maximum decrease in acrylamide formation to reach 78% in fried potatoes.     

A First Approach of Using Ultrasound as an Alternative for Blanching in Vacuum-Packaged Potato Strips

The effect of ultrasound (US) (40 kHz, 200 W, 3 min), blanching (85 °C, 3.5 min), and the combination of both methods was evaluated on the quality of vacuum-packaged potato strips stored at 3 ± 1 °C for up to 10 days. For this study, two cultivars of potatoes were assessed. For blanched Agata samples, the lightness (L*) decreased over 12 % (p < 0.05). Moreover, their hue increased up to 100, obtaining lesser yellow potato strips. In contrast, US did not affect the hue values. The losses of firmness of blanched potato strips were notable (35 % for Agata and 51 % for Agria), whereas US did not change this property (p < 0.05). Nevertheless, no significant differences were found in the total starch content at 10 days. Agata and Agria showed different metabolic behaviors of sucrose in the refrigerated storage. Therefore, Agria cultivar retained better color after frying. These results suggest that US had less impact on color and improve the firmness in vacuum-packaged potato strips with no added chemicals.