Acrylamide Reduction in Potato Chips by Selection of Potato Variety Grown in Iran and Processing Conditions

Background Acrylamide as a possible carcinogen is known to form in heated carbohydrate-rich food such as potato chips. In this study, the effect of three potato varieties (Agria, Sante and Savalan) and two blanching conditions ((75˚C for 9 min and 83˚C for 2.5 min) on the concentration of precursors and acrylamide reduction in potato chips was investigated. Results Results revealed that potato variety and blanching time-temperature ere important parameters for acrylamide formation in potato chips. Acrylamide content in Sante variety potatoes, which contained the highest amount of reducing sugars, was found to be the highest (8825μg/kg). However, Savalan, containing the highest asparagine concentration showed the lowest amount of acrylamide due to its lower reducing sugar content. Blanching reduced acrylamide formation. It was more efficient at 75˚C for 9 min, with an average reduction of 74%. The effect of three frying temperatures (170, 180 and 190˚C) on acrylamide formation was also studied just for the Agria potato variety. Increasing frying temperature led to a significant increase in acrylamide formation. Conclusion Potato variety and processing conditions were important parameters for acrylamide formation in potato chips. The combination of a suitable variety and appropriate processing conditions could considerably reduce acrylamide content

Effect of settling test procedure on sizing thickeners

The main portion of the water in mineral processing plants is recovered in thickeners. The required cross-sectional area for thickeners is generally calculated using the Coe-Clevenger, and the Talmage-Fitch methods. Over the years, changes which were made in the original settling tests procedure led to inaccurate results owing to floc structure variation especially for the flocculated suspensions. In this study, the effect of flocculation history, defined as the initial solids concentration where the flocs first were formed, on their settling velocity was investigated using batch settling tests. The suspensions used for settling tests were prepared by two different methods to arrive at equal solids fractions. The methods were the conventional procedure of adding solids to a known amount of liquid and decantation. Results of all settling tests (with and without flocculant) on various ores, and coal suspensions showed that the settling velocity of particles in any solids fraction of suspension in the mass settling region could be affected (up to 5-fold) by solids content of the suspension at which flocs were first formed. The decantation method provided lower settling velocity compared to that of the conventional procedure. This was attributed to different flocs structure and size which were indirectly verified by the settling tests. In the case of Interkarbon coal preparation plant, this translated to 27% underestimation of the thickener capacity. It was then concluded that the settling tests performed to determine the required cross-sectional area for thickening should be carried out either on a single sample with the solids concentration of the thickener feed or various concentrations from the feed to the underflow concentrations provided that the samples obtained by decantation of the feed sample. (C) 2013 Elsevier B.V. All rights reserved

Effect of mode of flocculation on flocs sedimentation behaviour in various regions of thickeners

Main portion of water in mineral processing plants is recovered in thickeners. The required surface area for thickeners is calculated based on the Coe and Clevenger theory where it is assumed, when no flocculants used, the settling velocity of particles in each layer in the free settling region is only a function of solids concentration in that layer. In this study, the effect of mode of flocculation, defined as the initial solids concentration where the floes first formed, on their settling velocity was investigated using batch settling tests. The pulps used for settling tests were prepared by two different methods to arrive at equal solids concentration. The methods were the standard procedure of adding solids to a known amount of liquid and decantation. The latter method made the change of mode of flocculation possible by decanting the dilute suspensions to obtain higher solids content pulps. Results of all settling tests (with and without flocculant) on copper, iron, lead and zinc ores, and coal suspensions showed that, unlike the Coe and Clevenger theory, the settling velocity of particles in any layer even in the free settling region is affected by solids content of the suspension where floes were first formed. For instance, the settling velocity of a layer of iron ore tailing with 22% solids in a flocculated (5 g/t) suspension varied from 1 .32 to 2. 73 em/min when the initial feed solids varied from 5 to 20%. Furthermore it was shown that the settling velocities of suspensions with equal solids content prepared by the two methods were different owing to the significant difference in their floes structures. It was concluded that the settling tests performed to determine the required surface area for thickening should be carried out etther on the single sample with the solids concentration of the thickener feed (after dilution if it is diluted) or on decanted samples. The conventional procedure of measuring settling velocities in various percent solids between the feed and the desired underflow is prone to large errors