Short communication: Organoleptic and physical characteristics of propolis from northeastern Argentina

Propolis is a combination of resinous, gummy, and balsamic substances of slimy consistency, which is collected by bees from different botanical sources and then transported to hives, where their physical and chemical properties are modified. Propolis contains active pharmacological substances and its demand as a natural drug is increasing in international markets. The objective of this work was to determine the organoleptic characteristics and physical parameters of propolis samples taken from 14 beehives in northeastern Argentina. In general, propolis came in irregular, opaque and shiny fragments with a hard consistency and contained external impurities. In most cases, the aroma was aromatic-resinous, attributed to the predominant flora in the geographical zone studied. This could be a positive factor for its commercialisation. Its flavour was predominantly insipid and it was a chestnut-brown colour. The water and ash contents found in different samples were very variable, indicating the presence of mineral elements from additional substances that bees introduce to make the propolis a more solid consistency. This preliminary study with no precedents in northeastern Argentina suggests that, in spite of the variability found, this natural product meets basic requirements for its commercialisation, and can be competitive on international markets.

to varnish the inside of the hive (including the panels) for disinfecting purposes, to fill in crevices, to reduce the size of entrances and to consolidate structural components.It is also used to cover the corpses of predators that enter the hive (beetles, rodents, small lizards), that become embalmed preventing their decomposition.
Active pharmacological substances found in propolis are of plant origin (Asis, 1989;Bianchi, 1996).Its composition is, therefore, highly variable owing to the diversity of the botanical sources used to produce it (Maidana, 1998).
The synergism between propolis and antibiotics make it an useful therapeutic resource, although in some cases local application of propolis can cause allergic reactions (Apimondia, 1976;Stangaciu, 1998).
Since it contains drugs of plant origin, national production is insufficient since it is exported in increasing amounts to international markets, mainly Germany, Italy, Japan and the US (Bedascarrabure, 1999a).With the aim of transforming commercial opportunities into real competitive advantages in the MERCOSUR region, quality standards for this product must be established.The aim of this work was to determine the organoleptic characteristics and the physical parameters of propolis from northeastern Argentina (NEA).
A record was made of all the apiaries in the region.A total of 14 apicultural producers were randomly selected from most of the provinces that make up this region (Corrientes, Chaco, Misiones and Formosa).
The predominant flora in the apiaries of Corrientes, Chaco and Formosa (Cabrera, 1976)  In contrast, in the Misiones province the predominant vegetation type corresponds to forests and savannah.The climax community (Cabrera, 1976;Zuloaga and Morrone, 1999  Three samples were randomly collected from each apiary, and a total of 42 were studied.These were collected by scraping the quadrants, covers and partitions of the hives using stainless steel knives.The samples were treated following the protocol designed by the Universidad de Santiago del Estero (UNSE) and the Instituto Nacional de Tecnología Agropecuaria (INTA) of Faimallá (Maldonado, 2000).The samples were placed in transparent polyethylene packets and afterwards in dark bags to protect them from the sun.
Most of the propolis was irregular opaque shiny fragments (Fig. 1A).The consistency was mainly hard (Fig. 1B), since the bees add soil and plant remains to make them harder, because of the softening effect of the high temperatures of the region, confirming the findings of Maidana (1998).Visible impurities were found in all the samples, with the remains of plants and other materials (Fig. 1C).Remains of paint, paper or cardboard were not found.
The aroma of all the samples studied, which is one of the most important characteristics for propolis consumers, mainly corresponded to resinous aromatic (37%) (Fig. 1D), attributed to the predominant flora in the apiary region, and can be a positive attribute for its commercialisation.In 77% of the samples the flavour was insipid (Fig. 1E).The predominant colour was brown with chestnut tones (Fig. 1F).
The water and ash contents of the samples ranged from 4 to 7 and between 2.5 and 4.54%, respectively (Fig. 2).This ash contents is indicative of the presence of mineral elements, which proceed from substances added by the bee (mechanical impurities such as clays, sands, etc) in order to solidify the propolis.The minerals found, of both organic and inorganic origin, are associated with the therapeutic properties of this product (Sosa López et al, 2000).Knowledge of the water contents of the propolis is useful to improve its conservation and storage by preventing the growth of moulds such as Mucor and Penicillium on its surface, that reduce the quality of this product.
The elements studied by absorption spectrophotometry were iron, copper, manganese, zinc and potassium, the concentrations of which vary depending on the origin of the propolis (Table 1).A highly significant difference was found in the iron contents of the samples from the Corrientes province, 1,056.7 mg kg -1 compared to that of samples from Chaco, 135.5 mg kg -1 .Physical parameters (water and ash contents) are in agreement with those reported by several authors for different regions of Argentina (Maldonado, 2000).

Figure 2 .
Figure 2. Water and ash contents or propolis.

Table 1 .
Mean contents of mineral elements in propolis of NEA (mg kg -1 ).The values correspond to the mean values of three repeats for 14 producers