Storage stability of a fluidized-bed agglomerated spray-dried strawberry powder mixture

Strawberry is a fruit with a high antioxidant capacity due to its richness in phenolic compounds that suffer a rapid post-harvest deterioration. Spray drying is an alternative to reduce losses; however, these powders present problems of instantanisation, making it necessary to implement agglomeration processes. During storage, powdered food products can undergo a series of changes in their amorphous state from a product initially in a vitreous state to a gummy state, where all properties are substantially modified due to the increased mobility of water in the matrix.

The study will serve as a tool for the determination of the shelf life of the chipboard once the critical values of the attributes selected as predictors of shelf life are defined.

The research objective was to evaluate the storage stability (6 months) of a fluidized bed agglomerated strawberry powder mixture at three temperatures (15, 25 and 25°C), a controlled environment at 65% relative moisture, and PET foil laminated film bags as packaging. Moisture, water activity, bulk and compacted density, Carr and Hausner indices, solubility, hygroscopicity, wettability, angle of repose, antioxidant capacities, total phenols, anthocyanins, vitamin C, color (CIE-Lab) and particle size were monitored.

ANOVA showed statistically significant differences (p<0.05) for all dependent variables concerning storage time; storage temperature had no significant effect on S, ABTS, DPPH and Hu. The time-temperature interaction during storage had no significant effect (p>0.05) on S, ABTS, DPPH, Hu and L. The agglomerate showed moisture and aw values that confer excellent stability against deterioration reactions; it retained good fluidity, low cohesiveness, and retentions above 50% for antioxidant capacity, 76% for total phenols, 39% for anthocyanins, and 40% for vitamin C; particle size was retained during the evaluation. The color was only affected in the 35°C treatment from the fifth month onwards. Conclusions: The study will serve as a tool for the determination of the shelf life of the chipboard once the critical values of the attributes selected as predictors of shelf life are defined.