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.     

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。     

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。     

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。     

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…     

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.     

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.     

Optimization of Nutrient Retention During Processing: Ascorbic Acid in Potato Dehydration

A kinetic model representing ascorbic acid degradation in potatoes as a function of moisture content and temperature was used to find optimal dryer-temperature control paths for minimizing ascorbic acid loss during air drying of potato disks. Optimal dryer-temperature control was also determined for minimizing drying time given a specified minimum retention of ascorbic acid. Constraints were placed on the final moisture content and the air temperature. Optimization was achieved using a simulation-optimization approach based on the complex method.     

臭氧水处理对蔬菜中维生素C和胡萝卜素含量的影响

用臭氧水处理菠菜、小白菜、黄瓜三种蔬菜,测定不同处理时间各蔬菜中维生素C(VC)和胡萝卜素的含量,结果表明：随着处理时间的延长,蔬菜中还原型VC的含量明显下降,但总VC的含量维持不变;胡萝卜素的含量随着处理时间的延长,都有明显的下降。     

维生素C在新陈代谢中的生理功能

维生素C不仅通过直接清除活性氧簇还通过间接维持其他抗氧化剂的还原态在生物体内起着非常重要的抗氧化作用,而且在更多其他方面也起着非常重要的作用。本文从维生素C的抗氧化作用、作为双加氧酶的共基质所起的作用、维生素C基因表达上所起的的作用以及维生素C在脂类氧化和DNA损伤中的作用做了综述,希望人们以更加全面的观点来看待维生素C。     

低蛋白馒头水分保持研究

主要研究几种常用水分保持剂对低蛋白馒头水分保持效果影响,并通过正交实验确定几种水分保持剂最佳添加量,即:卵磷脂0.3%、磷酸三钙0.3%、瓜儿豆胶0.5%、麦芽糖2.5%。     

涂料保水性的影响因素及改进措施

该文通过生产实践中的一些经验总结出影响涂料保水性许多因素,同时提出了一些改进措施,为很好地控制涂料保水性,提高涂布效果提供指导。