Herramientas analíticas en la clasificación de mieles en base a criterios de calidad e inocuidad

Abstract

[EN] The present PhD thesis has two distinct objectives: 1. To evaluate the techniques that have been used routinely in the quality control of honey, at both an industrial and commercial level, and to compare them with other unconventional alternatives, and 2. To evaluate the effectiveness of monitoring the raw material in the packaging industry (carried out on receiving batches of raw honey,) to meet the legal limits regarding the presence of chemical residues. Also, to assess the risk to the consumer as a result of exposure to such residues when there is a legally established maximum residue limit (MRLs). In general, the physicochemical parameters that have been used conventionally in the classification of honey do not permit good differentiation in terms of monoflorality. While the botanical origin of honey has a clear impact on some of them, such as the color and electrical conductivity, levels of certain physicochemical parameters may vary depending on the year of harvest (especially color) and beekeeping practices. In this line, the beekeeper has an important role in the variability of some of these parameters, especially in regard to HMF and moisture, and even in the characteristic varietal color that the market requires. Therefore, good beekeeping practices are essential to obtain the product that the consumer expects and legislation requires. The alternative techniques tested in this study, such as identifying characteristic volatile compounds in the volatile fraction of honey, and the application of an electronic tongue made with metals, have provided useful and promising results in the classification of honey to complement the information obtained by pollen analysis. The use of chemical fingerprinting, such as for methyl anthranilate in citrus blossom honey, is particularly useful when the percentage of pollen is particularly low, as in the case of sterile hybrids or when pollen and nectar production is not simultaneous. This PhD thesis suggests reconsidering the level of this compound required in Spanish citrus honey; proposing a minimum value of 1.2 mg/kg (greater than that recommended in other studies for Italian citrus honey). However, only taking this parameter into consideration in the case of honey with a surprising low percentage of citrus pollen, and after evaluating its organoleptic and physicochemical properties. The presence of certain compounds, in the volatile fraction of the honey, is decisive in its differentiation; botanical origin having the greatest influence on discrimination and to a lesser extent the geographical origin. For example, carvacrol and ?-terpinene are characteristic of tilia honey; ?-pinene and 3-methyl-2-butanol of sunflower honey; and cis-linalool oxide of acacia honey. The information obtained with an electronic tongue (made with metal sensors) in combination with appropriate multivariate statistical techniques (Principal Component Analysis and Neural Networks) has demonstrated that this system allows the differentiation of honey by botanical origin with a success rate…