Functionality of amidated low methoxyl pectin and xanthan gum blends on the texture and color of mashed potatoes

Blends of amidated low methoxyl (ALM) pectin and xanthan gum (XG) were added to fresh (F) and frozen/thawed (F/T) mashed potatoes. Product was tested by instrumental texture profile (TPA), color, expressible water (Ew) and sensory analyses. A central composite rotatable experimental design was used to study the effects of variation on ALM pectin (1.5-4.5 g/kg) and XG (0.5-2.5 g/kg) concentrations. The effects were highly dependent on the levels of ALM and XG added, although XG influenced the mechanical behavior, color and water-holding capacity of the mashed potatoes more than ALM pectin. F and F/T mashed potatoes with 3 g/kg added ALM pectin and 2.91 g/kg added XG exhibited the greatest consistency, adhesiveness and gumminess, which could be associated with an increase in the amount of XG-water interactions. Instrumental and sensory tests showed that, when 3 g/kg of ALM pectin and 1.5 g/kg of XG were included in the formulation, the mechanical and functional properties of F/T product were very acceptable, with almost no detectable changes in color attributes, and very good overall acceptability (OA) associated with a pronounced creamy sensation conferred by the XG. PRACTICAL APPLICATIONS: Most frozen products exhibit some loss of quality due to freezing, frozen storage and thawing. In the case of mashed potatoes, freezing and thawing has a detrimental effect on physical properties and water-holding capacity (WHC). The results show that the quality after freezing and thawing may be improved by the addition of 3 g/kg of amidated low methoxyl pectin and 1.5 g/kg of xanthan gum, incorporation of dietary fiber, improvement of mashed potatoes texture by retarding starch retrogradation and increasing WHC, and enhancing the principal characteristics determining consumer acceptance. These results have important implications for the production of frozen/thawed mashed potatoes with improved sensory quality and freeze-thaw stability over time.