Steady shear and yield stress data of fresh and frozen/thawed mashed potatoes: Effect of biopolymers addition

Oscillatory Rheological Properties of Fresh and Frozen/Thawed Mashed Potatoes as Modified by Different Cryoprotectants

“…Oscillatory properties indicated that the addition of ALM pectins to F mashed potatoes produced neither thickening nor gelling properties, whereas only in sample F/T-ALM5 there was incipient thickening, indicating improved freeze/thaw stability. A previous study also showed a lack of effect on the flow parameters related to the lowest level of ALM pectin (1.5 g kg −1 ) (Fernández et al 2007). ALM pectins form gels in the presence of divalent cations (mainly Ca 2+ ) through associations between sequences of charged groups belonging to two different chains (egg-box binding) (Gilsenan et al 2000).…”

“…In this study, oscillatory measurements indicated that the addition of both ALM and HM pectins to mashed potatoes at concentrations ranging between 3 and 5 g kg −1 could potentially prevent the softening caused by freezing and thawing and improve freeze/thaw stability. However, adding higher levels of ALM and HM pectins (3-8 g kg −1 ) increased the viscosity measurements of F/T mashed potatoes compared to their fresh counterparts (Fernández et al 2007), evidencing that much stronger structures are obtained when mashed potatoes with added pectins are frozen and thawed. Therefore, steady shear and yield stress data would appear to be more suitable properties to detect texturizer effects as a consequence of pectins addition and processing on the rheology of mashed potatoes.…”

“…Sensory evaluation was conducted by a four-member panel with specific training in potato purees for 6 years (Alvarez et al , 2007aCanet et al 2005;Fernández et al 2007). Each sample was tested twice and average scores calculated, so that each sample was tested eight times in all.…”

“…This darkening in the frozen samples might be partly because of greater dehydration during final microwave thawing, because the fissures formed by the growth of ice crystals during freezing favor the release of water, and also partly to the fact that microwave thawing for 20 min gives the samples some color. Of course, this darkening is unlikely to be of major importance, as anyone preparing F/T mashed potato is unlikely to have an F sample with which to compare it (Fernández et al 2007). The minimum color ratio measured corresponded to F/T mashed potatoes containing 8 g kg −1 ALM and HM pectins.…”

“…Rheological characterization of polysaccharide systems entails viscosity and viscoelastic measurements. Recently, the effect of biopolymers addition on the steady shear and yield stress data of F and F/T mashed potatoes has been showed (Fernández et al 2007). Optimum consistency and homogeneous texture for good mouth-feel are desired characteristics for F/T mashed potatoes.…”