Effect of prefreezing treatments on quality of mango (Manguifera indica L.) during frozen storage
Rincon, Angela Maria
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At the moment there is a high demand for high-quality fruit ingredients to be used in many food formulations such as pastry and confectionery products, ice cream, frozen desserts and sweets, fruit salads, cheese and yoghurt. The overall objective was to improve quality of frozen mango using two types of food cryoprotection: one was the reduction of water content of the fruit (osmotic dehydration) and the other was the formulation of mango pulp with carbohydrates of different molecular weight to increase frozen stability. Osmotic dehydration was able to modify quality parameters of slices before and after frozen storage. Values for some **parameters such as vitamin C, lightness (L), chroma (C), and firmness for non osmotically dehydrated slices were significantly higher than osmotically dehydrated slices. However, treatments carried out with osmotic solutions (especially those with high concentrations of sucrose) improved significantly the quality of mango slices after frozen storage. Higher moisture losses and solid gain values were reported for slices from the highest osmotic solution oconcentration. Thus, slices dipped in 30Brix were better protected against freezing damage. Effects of sucrose concentration on the slices and ripening stage on frozen-thawed mango flavor perception were determined. Six flavor descriptors (color, flavor, sweetness, sourness, firmness and juiciness) were evaluated by a sensory trained panel. All descriptors were affected by sugar content and ripening stage. To study the effect of mango fruit composition on frozen stability, five pulp samples were prepared and evaluated in terms of glass transition temperature modification and its influence on ascorbic acid retention. State diagrams and sorption isotherms were determined in order to predict freezing storage conditions for the pulps. Glass transition temperature was found to be a function on the composition of the mixture of carbohydrates present on the pulps. As the molecular weight of carbohydrates used for the pulps formulation increased, so did T’g. Maltodextrin M150, which had the highest T’g value, had the highest protective effect on ascorbic acid degradation. However, knowledge of T’g alone was not sufficient to know whether a cryoprotectant is a good cryostabilizer or not. Sensory and textural analysis were recommended in addition to evaluate cryoprotectan effects during frozen storage.