Viscosity Measurements of Potato Starch Paste with the Rapid Visco Analyzer

Abstract

Viscosity behaviour of potato starch paste was measured with the Rapid Visco Analyzer (RVA, Newport Scientific, Warriewood, Australia). By reason of high viscosity properties of potato starch suspensions, starch concentration was reduced from 3.0 to 2.0 g starch weight (14% moisture) in 25 rnl distilled water. In view of Brabender viscograms a short temperature profile (13 min including heating, stable hot phase, and cooling) achieved the best results. Reproducibility of RVA-measurements was high as well with new canisters as with re-used ones. Coefticient of variation (?.Yo) was below 2%. A comparison of RVA and Brabender viscograrns pointed out a close correlation of r = 0.94 for both, the peak viscosityand the viscosity difference between peak and trough. Viskositatsmessungen von Kartoffelstslrke mit dem Rapid Visco Analyzer. Das Viskositatsverhalten von Kartoffelstlrkekleistern wurde mit dem Rapid Visco Analyzer (RVA, Newport Scientific, Warriewood, Australien) gemessen. Aufgrund der kraftigen Viskositatsauspragung der Kartoffelstarke wurde die Starkekonzentration von 3,O auf 2,O g Starke (14% Feuchte) in 25 ml destilliertem Wasser reduziert. Mit Blick auf das Brabender Viskogramm erzielte das kurze Temperaturprogramm (13 min einschliefilich Aufheiz-, stabiler HeiD-und Abkuhlphase) die besten Ergebnisse. Die Reproduzierbarkeit der RVA.Messungen war sowohl rnit neuen als auch mit gereinigten Mefieinsatzen hoch. So lag der Variationskoeffizient (soh) unter 2%. Ein Vergleich zwischen RVA-und Brabender Viskogrammen wies mit einem Korrelationseffizienten von r = 0,94 eine hohe Ubereinstirnmung sowohl bei der Spitzenviskositat als auch bei der Viskositatsdifferenz zwischen hochstem und niedrigstem Wert auf.

Multivariate Comparison of the Brabender Viscograph and the Rapid Visco Analyser Using Cross-linked Starch

“…However, these differences are modest. The shear of both viscographs [13] and the relative standard deviation [5,6] is comparable. Optimization can also be obtained by limiting the sample set first and adjusting the methods to the set or by fine-tuning the multivariate modeling.…”

“…However, because of the small sample volume (28 ml in comparison with 450 ml) the RVA can heat the starch suspension faster, resulting in an overall program of 10 min. The speed does not affect the accuracy, because in major parts of the RVA viscogram the relative standard deviation is within 2 % [5,6], which is comparable with the Brabender Viscograph [6]. Since the RVA is fast, it is interesting to find out in what way RVA and Brabender are related.…”

“…The relation has been described in a univariate approach by Haase et al [5] and Deffenbauch and Walker [7], which gave evidence to a close correlation of both apparatus. This has also been presented by Thiewes et al from a covariance matrix of RVA and Brabender [6].…”

“…The viscograph applies a well defined heating program to a starch/water suspension and registers the resistance to a fixed rotation speed. The Brabender viscogram gives valuable information for product quality assessment, however, usual Brabender methods without cooling take 50 min analysis time [5]. Because the production time of cross-linked starch is only several hours, the Brabender Viscograph is less suited for process control.…”

Potato starches: variation in composition and properties between three genotypes grown at two different sites and in two different years

“…Results produced by the two instruments are very similar. 30 Some of the viscosity data are presented in Fig 2. For clarity, only peak, hot paste and ®nal viscosities are shown. Since breakdown (peak viscosity À hot paste viscosity) and setback (®nal viscosity À hot paste viscosity) are both derived mathematically from these parameters, neither has been included.…”