Organic honey from Trás-Os-Montes region (Portugal): Chemical, palynological, microbiological and bioactive compounds characterization

Abstract

At the present time, the quality, integrity, sanitation and nutritional value of honeys receive attention on an international level due to the increasing content of chemicals in the aforementioned matrix. This work was conducted to evaluate the quality of 75 organic honey samples from the Trás-Os-Montes region (Portugal). Mean values obtained for physico-chemical parameters were: pH 3.7; 15.6% moisture; 0.26 mS/cm electrical conductivity; 0.25% ash; 1.1 mg/kg HMF; 15.3 Gothe diastase activity; 40.3 meq/kg free acidity; 67.8% invert sugars and 2.7% apparent sucrose. All honey samples can be classified as monofloral Erica sp., as showed by pollen features. The amounts of phenols and flavonoids in the samples were also determined. In respect to sanitary quality (fecal coliforms) and safety (sulfite-reducing clostridia and Salmonella), all organic honey samples were negative. Furthermore, yeast and molds were detected in low counts, with mean values obtained of 5.5 cfu/g and the value of total aerobic mesophiles obtained from honeys was established in 1.3 × 10² cfu/g ± 7.5 × 10¹ cfu/g. The levels of flavonoids had a stronger impact on both mesophiles (p = 0.0004) and molds (p = 0.0138) than the sucrose concentration (p = 0.001 and 0.0278; respectively). The results reported in this study should be introduced in the organic honey label, and may help beekeepers, the industry, researchers and consumers better understand honey properties.

Introduction

Apiculture is a valuable and exceptional example of an environmentally sustainable production model, crucial for biodiversity and for agriculture, and characterized by a confluence of: (i) Economic interests (production of honey and by-products of the hive, which provide returns); (ii) Social aspects (fixation of the rural population in territories where hardly any other economic activities) and (iii) Environment maintenance (not only environmentally friendly but also as a service to society through the pollination of cultivated and wild fields) (Allsopp et al., 2008).

Today, having survived all kinds of climatic changes, bees are threatened, and therefore global food security, if pollinators, mainly honeybee, decline or disappear (Cuthbertson and Brown, 2009). The cause of the problem is still unknown, which is why it is being described as Colony Collapse Disorder (CCD) and researchers suspect this may be due to a combination of various diseases, environmental pollution, and farming practices, mainly due to an abusive use of increasingly toxic phytosanitary products and large monoculture cropping (Oldroyd, 2007).

When analyzing and studying the therapeutic properties of honeys, modern science has made it possible to specify their medical significance for healing wounds and burns (Molan, 2001), oncology care (Bardy et al., 2008), as well as its antioxidant and antimicrobial factors (Gomes et al., 2010, Akbulut et al., 2009, Theunissen et al., 2001). It is clear that honeys to be used for therapeutic purposes should be harvested in areas with no contamination sources (Feás and Estevinho, 2011).

In any case, concerns about traces of numerous toxic substances have prompted some demand for honey that is certified as organic (Rial-Otero et al., 2007). Organic honey production is an ecologically based system, which encourages the use of good agricultural practices to maintain the agricultural ecosystem balance and diversity, promoting the sustainable use of natural resources, environmental quality, animal welfare and human health (EU, 2007). Research results indicate that the botanic origin of honey, different beehive types, and the material beehives are made of, have an influence on the development of bee diseases and the quality of honey (Tucak et al., 2004).

The progressive increase in the market of imported honey, with lower prices and inferior quality, has recently led to a growing need to asses authenticity of local, specially monofloral honeys, using a full quality control based on a physicochemical, microbiological and geographical description (Andrade et al., 1999, Azeredo et al., 2003, Pires et al., 2009, Feás et al., 2010a, Feás et al., 2010b, Du Toit et al., 1995). However the full characterization of honey is not abundant and there is a lack of information about the characteristics of honey certified as organic (Magkos et al., 2003).

The organic strict guidelines mean that is almost impossible for any beekeeper to be certified as organic. However Portugal possesses a very diverse natural heritage thanks to its geographical location and geophysical conditions (Araújo, 1999). Moreover, presently in the Portuguese continental territory there are 29 Special Protected Areas and 60 Sites of Community Importance which deals with the conservation of natural habitats and wild fauna and flora that are considered to be threatened in the European Union (EU, 1992).

Currently, Portugal has the highest number of honeys bearing the European Protected Designation of Origin logo, a total of nine, which are produced, processed and prepared in a given geographical area using certified know-how (EU, 2006). The detailed characterization of the different honey types existent in Portugal is important, once it will allow the establishment of technical specifications, avoiding occurrence of adulterations.

The present study aimed to characterize, for the first time, organic honeys harvested in Portugal, and more specifically in the Trás-Os-Montes region, in respect to: (i) floral nectar origin, (ii) physico-chemical parameters, (iii) bioactive compounds and (iv) microbial safety.