Assessment of Trans Fatty Acid Level in French Fries from Various Fast Food Outlets in Karachi,Pakistan

The purpose of this study is to determine the trans fat level in French fries sold in different fast food outlets in Karachi. In the present study, attenuated total reflectance‐Fourier transform infrared (ATR‐FTIR) spectroscopy was used for the quantification of trans fatty acid (TFA). A number of studies have been reported on trans fat in different regions of the world, but no categorical study has yet discussed the trans fat in fast food products in Karachi. Amongst the samples examined, the total trans fatty acid content was in the range of 0.11 ± 0.01–24.00 ± 0.25 %. Most of the samples contain a high percentage of TFA. There is an urgent need to monitor and regulate the level of trans fat in order to reduce the health risk to the consumers of fast food items in Karachi, Pakistan.     

Total and soluble oxalate content in legume vegetables used in the preparation of frozen products for consumption

The aim of the investigation was to compare oxalate retention in two types of frozen product prepared for consumption after frozen storage: one obtained using the traditional method (blanching‐freezing‐frozen storage‐cooking) and a convenience food involving cooking‐freezing‐frozen storage‐defrosting and heating in microwave oven. The investigation included three species of legume vegetables: immature (wax‐stage maturity) seeds of broad bean and green pea, and French bean. Fresh broad bean seeds contained 53 mg total oxalates in 100 g fresh matter; pea 38 mg; and French bean 88 mg. Soluble oxalates comprised 53, 58 and 72% of total oxalates. The treatments applied resulted in reduction of the level of total and soluble oxalates, and oxalate to calcium ratio (broad bean and French bean); there was no influence on the level of calcium bound as calcium oxalate; true retention of oxalates was lower than apparent retention (green pea and French bean).     

四季豆中粗筋组织估量的仪器检测

本文研究了用TA-XT_2组织仪快速估量四季豆中粗筋含量的仪器测定方法和最佳分析参数,为四季豆罐藏加工原料的选择与质量控制提供了新的检测手段。     

Legal limit for reducing sugars in prefabricates targeting 50 μg/kg acrylamide in French fries

A legal limit for the reducing sugars in the prefabricates for French fries is a simple and efficient measure to reduce the exposure to acrylamide from the predominant source for many consumers. The acrylamide content of French fries of comparable crispiness is approximately proportional to the concentration of the reducing sugars glucose and fructose in the potato sticks. On average, optimally prepared French fries from prefabricates with a (moderately low) sugar content of 0.3 g/kg contained 32 g/kg acrylamide. With 0.15 g/kg reducing sugar even severe overfrying at 170 °C only resulted in 90 g/kg acrylamide, i.e. a low sugar content keeps acrylamide low even under inappropriate frying conditions. In the prefabricates, the sugar content is about 10% lower than in the raw potato (resulting from the effects of blanching and prefrying). It is similar to that in the finished French fries, which enables one to distinguish whether a high acrylamide content in French fries results from high sugars in the raw material or unsuitable frying conditions. An average concentration of 50 g/kg acrylamide in French fries could be targeted by limiting the reducing sugars in the prefabricates to 0.7 g/kg and the frying temperature to 170 °C. Even considerable overfrying in terms of duration can be tolerated then.     

Reduction of acrylamide formation in French fries by microwave pre‐cooking of potato strips

In this study, the effect of microwave pre‐cooking of potato strips on the resultant acrylamide levels in French fries was investigated. Control and microwaved (10, 20, and 30 s at 850 W) samples were fried at 150, 170 and 190 °C for predetermined times. Surface and core temperatures of potato strips were acquired during frying, and acrylamide content in the surface and the core regions were determined separately. The results showed that microwave application prior to frying resulted in a marked reduction of acrylamide level in the surface region, whereas a slight increase was noted for the core region. When the potato strips were subjected to frying after a microwave pre‐cooking step, acrylamide content in the whole potato strip was reduced by 36%, 41%, and 60% for frying at 150, 170, and 190 °C, respectively, in comparison to the control. Copyright © 2006 Society of Chemical Industry     

基于传质特性研究油种类对煎炸薯条质构的影响（网络首发、推荐阅读）

以"荷兰十五"品种的马铃薯和4种食用油为研究对象,考察煎炸过程中油种类对薯条质构、失水吸油动力学常数、水分空间分布、晶体结构以及微观结构的影响。结果表明:棕榈油和米糠油炸制薯条的表面硬度高于其它两种油。水分损失动力学结果表明使用棕榈油炸制薯条的表面水分损失速率最快(0.053 6 s^-),其次是米糠油(0.027 5 s^-),高油酸葵花油最慢(0.021 6 s^-1)。核磁共振影像也证实了这一结果。X-射线衍射结果表明米糠油和棕榈油炸制薯条的淀粉-脂质复合物含量高于其它两种油。扫描电镜结果表明棕榈油和米糠油炸制薯条的表面比其它油更致密。表面失水快、淀粉-脂质复合物含量高以及表面的致密性对薯条质构的增加起到重要的作用。     

多效唑、矮壮素和摘心对孔雀草的矮化效应

采用PP333、CCC和摘心处理孔雀草,试验结果表明:PP333、CCC和摘心均对孔雀草具有矮化生理效应,药剂处理矮化效应优于摘心处理。随着药剂浓度增高,POD,CAT,SOD,IAA氧化酶活性增强,矮化作用也随之加强;同时,叶绿素含量增高,花期和总生育期延长,花枝增多,花径增大。比较各种处理,以15%PP333的500mg.L-1喷4次处理,孔雀草矮化和观赏综合效应最佳。     

Apparent diffusivities of reducing sugars in potato strips blanched in water

The mechanism of reducing sugar losses was investigated in potatoes cut into 9.5 × 9.5 mm and 13 × 13 mm strips and blanched for 300–2400s at different temperatures between 70°C and 100°C. Experiments were carried out using large amounts of well-agitated water. Assuming no chemical reaction and using appropriate solutions of the unsteady state diffusion equation for square parallelpiped geometry, the apparent diffusivities, D_a, of reducing sugars in the potato matrix were determined at different temperatures. the incorporation of the dimensions of the strips in the solution of the diffusion equation was sufficient to explain the effect of size on losses. Values of D_a were found to be in the range 1.2 × 10^-11 1.7 × 10^-11 m²s^-1 and could be correlated with temperature according to the Arrhenius law.     

浅析灌江纳苗对涨渡湖湿地水质及泥沙的影响

涨渡湖湿地是我国重要的淡水湿地生态系统之一。由于围垦及江、河、湖泊人为阻隔,涨渡湖湖区逐渐淤积减小,水体流动性逐年变差,水质状况呈逐年下降趋势,造成调蓄洪水、净化水质等湿地功能的丧失。本文对涨渡湖挖沟闸及湖区内灌江纳苗前后水质、泥沙浓度等进行了取样分析。实测资料分析显示:灌江纳苗后湖中心各离子含量变化较小,湖汊及挖沟闸内离子浓度明显减小;灌江纳苗在引入长江水的同时,也引入了大量泥沙并沉积在涨渡湖湖汊及主湖区中。     

Retention and distribution of polyphenols after pan-frying of French fries in oils enriched with olive leaf extract

ABSTRACT:  Palm oil, olive oil, and sunflower oil were supplemented with an extract rich in polyphenols obtained from olive tree ( Olea europaea ) leaves at levels of 120 and 240 mg total polyphenols per kilogram of oil. Pan-frying of potatoes was performed in both the enriched and the nonsupplemented oils under domestic frying conditions. Total polyphenol content was estimated by the Folin–Ciocalteau assay, oleuropein was determined by HPLC analysis, while other individual polyphenols by GC/MS analysis. Fourteen polyphenol species were identified in the olive leaf extract, among which oleuropein predominated (1.25 g/kg olive leaves). All the enriched oils contained oleuropein before and after frying. Oleuropein as well as other polyphenol species were detected in all French fries cooked in enriched oils. Polyphenol intake by consuming French fries pan-fried in the enriched oils was calculated to be 6 to 31 times higher than that in the case of French fries fried in commercial oils, being dependent on the frying oil type.