Effect of freezing on the rheological characteristics of protein enriched vegetable puree containing different hydrocolloids for dysphagia diets

Abstract

This study optimized the formulation of protein-enriched vegetable purees designed for people with swallowing difficulties and investigated the effect of different storage conditions (freezing and refrigeration) on their nutritional, rheological and textural properties. Two proteins (casein and pea protein) and four hydrocolloids (guar gum, tara gum, xanthan gum and carboxymehtylcellulose) were combined and their behavior analyzed. The formulations were a good source of protein and antioxidants ensuring a significant supply of protein (6.1–6.7%) and antioxidant capacity (43–53 mg phenolic compounds/100g). The addition of an optimum amount of hydrocolloids allowed the target “pudding” viscosity to be achieved. The formulations containing pea protein were more affected by freezing, which decrease their viscosity, and showed a weaker internal structure and a lower firmness after freezing/thawing when compared with casein formulations. Samples with xanthan gum in general showed better stability. These results indicate that freezing can be a good alternative for pre- serving casein-enriched vegetable puree elaborated with xanthan gum designed for people with swallowing difficulties.