Effect of storage conditions on bee pollen quality

Bee pollen is a complete and valuable food that contains proteins, carbohydrates, lipids, fibers, minerals, vitamins, enzymes and phenolic compounds. Their chemical composition is influenced by the conservation methods applied, especially if these involve heat, as well as by the storage processes. The main goal of this study was to evaluate the effect of two storage conditions on the nutritional and microbiological quality of nine Portuguese pollen with different botanical origin after six months of storage. Pollinic analysis of the samples allowed their codification according to the predominant pollen, being 7 monofloral and 2 multifloral. All samples were subjected to two different storage methods: frozen and dehydration. The quality of pollen was assessed through several chemical and microbiological parameters and the fatty acid profile. A two-way analysis of variance (ANOVA) was performed to analyse the effects of the storage method and the different predominant pollen species The results were also subjected to a multivariate analysis to study the relation between variables and cases. Of the several parameters assessed only pH, total acidity, fibres and ashes content were not significantly affected by the storage methods (P>0.05). Total phenols, flavonoids, vitamin C and !l carotenoid content were strongly influenced by the botanical origin as well as by the dry process of pollen. The composition of fatty acids was more affected by the storage method, since this factor explains higher percentages of the total variability. Regarding the microbiological quality of the stored pollen, in general the populations of mesophilic aerobic and the yeasts and molds presented higher levels in frozen pollen. This study revealed that the storage method is more significant than the botanical origin to establish differences between the types of pollen analyzed and the frozen process is recommended in order to preserve the nutritional values of this product.