Introduction

In addition to its significant nutritional characteristics, honey from stingless bees (family Apidae, tribe Meliponini) is widely used in traditional medicine in countries such as Mexico, Guatemala, Costa Rica, Colombia, and Brazil. Due to its properties, this honey has shown effectiveness in controlling eye, respiratory, digestive, gynecological, and dermatological ailments, placing the product in great demand in health food stores and pharmacies (^{Grajales-Conesa et al. 2018}).

The physical and chemical parameters of natural honey, such as the concentration of hydroxymethylfurfural (HMF), color, acidity, and electrical conductivity, are strictly defined and constitute quality indicators that characterize individual varieties of honey. Measurement of these parameters is relatively simple, and the information provided is invaluable (^{May-Canché et al. 2022}) and has allowed several laboratories to conduct in-depth studies on the subject (^{Hossain et al. 2022}).

The parameter used for measuring the aging of honey is HMF concentration, which is the most significant intermediate product of two reactions: degradation of hexose and decomposition of 3-deoxyosone in the Maillard reaction (^{Salis et al. 2021}). The color depends on several factors, although it is primarily related to the botanical origin and composition of the nectar, collection process, temperature, and storage time (^{Tkáč et al. 2022}). Water activity (aw) is a significant factor in preventing or restricting microbial growth and, in many cases, is the key parameter responsable for the stability of food, modulation of the microbial response, and determination of the type of microorganisms found in foods (I^{khsan et al. 2022}).

The pH of honey is low which inhibits the presence and growth of microorganisms and allows the compatibility of honey with many food products in terms of pH and acidity (^{Islam et al. 2022}). Stingless bees or meliponines represent “environmental health” for the ecosystems that they inhabit, as well as balance, to the extent that they actively participate in pollination of most flowering plants. In addition, these stingless bees are the backbone of the food chain that gives meaning to the complex and fragile balance of life in jungles and tropical and subtropical forests (^{de Matos Barbosa et al. 2022}). Meliponiculture is an activity that is still in an early stage of development and requires a greater research effort. In addition to their biology, distribution, and classification, more information about meliponines is needed regarding their properties, uses, production, and transformation. Moreover, more information is needed about

marketing of products from meliponines and especially regarding their relationship with native and cultivated plants within agro-ecosystems (^{Bratman 2020}, ^{May-Itzá et al. 2022}, ^{Simms and Porter-Bolland 2022}). Despite the fact that several species of these stingless bees are distributed in Mexico, their study has been limited. This study aimed to physically and chemically characterize honey from these stingless bees in the locations Cañada Blanca and Manuel León of the municipalities Amatlán de los Reyes and Fortín de las Flores, Veracruz, Mexico, in a completely randomized experiment with a factorial design, being the two study factors: location of sampling (L) and year of sampling (Y).

Materials and methods

Results and discusión

In Table 1, the main effect of the sampling site is observed, in which the sample from Fortín de las Flores had the highest average with a value of 4.8 ± 0.01 (n =6). With respect to sampling year, wo statistical groups were found, in which the 2018 harvest exhibited the highest pH (p ˂ 0.01). For the interaction of both study factors, three statistical groups were obtained (p ˂ 0.01), in which the Fortín de las Flores sample from both harvest years had a higher pH (4.81).

Physical and chemical characterization is usually performed to determine the qualities of honey, especially for marketing purposes. To analyze the composition of the honey, established parameters for assessing honey from Apis mellifera and S. mexicana were used. For the latter, ^{Vit et al. (2004)} have proposed some reference values. Free water is measured as the aw and is considered an indicator of purity and the degree of maturity and stability of honey during storage (likelihood of decomposition by fermentation) (^{Da Silva et al. 2016}). The average values reported in honey range from 0.77 to 0.91 (^{Ávila et al. 2019}). The aw values obtained in this study are slightly lower than those reported previously.

Many species of bacteria will grow if the aw is between 0.94 and 0.99, and the aw of ripened honey does not support the growth of yeast. For this reason, diluted honey with a higher awill not be effective against those species of bacteria that grow most rapidly at an aw of 0.99 (^{Saranraj et al. 2016}).

Assessment of HMF is used to determine the quality of honey. In fresh honey, this compound is usually not present. High concentrations of HMF in honey indicate overheating, poor storage conditions, and aging of the honey (^{Tadese et al. 2020}). The Codex Alimentarius Commission and the European Union established that the allowable concentration of HMF in honey must not exceed 80 and 40 mg kg^-1, respectively. However, the European Union provides for some exceptions, for example, the allowable value in honey from countries or regions with tropical climates is up to 80 mg kg^-1, as is the case of honey tested in our country (^{Codex Alimentarius Alinorm 2000}). In this study, the recorded values of HMF in all places and years of sampling are low, which is indicative of young, high-quality honey.

The color of liquid honey ranges from clear and colorless to dark amber or black and depends on its botanical origin, age, and storage conditions. The color values obtained in this study were generally above 60 mm Pfund, indicating dark honey. When analyzing the color of honey samples produced in the provinces of Chaco, Argentina, ^{Salgado and Maidana (2014)} reported differences depending on the vegetation at the collection site. They observed that dark honey samples were obtained from areas where the native forests still prevail and forest species are the primary source of nectar, while clear honey simples were collected in agricultural areas of the province, where there is little crop diversity. Likewise, in this study, the honey that had the highest color value was obtained from Fortín de las Flores, an area with greater variability of flora and fewer disturbances, given the distance that stingless bees travel to find meliponaries. While the Cañada Blanca location also features little disturbance, its landscape is dominated by coffee and citrus orchards.

Similar to color, the EC is a good criterion for the determining the botanical origin of honey and is therefore a variable often used in the control of quality and purity. Honey contains organic acids and mineral salts, compounds that are chemically “ionizable” when in solution and can conduct electricity (^{Yadata 2014}). In the case of honey collected in Fortín de las Flores, there was a positive relationship between color and EC, which is consistent with the results reported by ^{Salgado and Maidana (2014)}. Furthermore, the EC values obtained, particularly in honey from Fortín de las Flores, greatly exceed the value established by Codex Alimentarius for floral honey, which is 0.8 dS m^-1 (^{Codex Alimentarius Alinorm 2000)}). These high EC values could indicate the presence of honeydew in the honey (honeydew honey), which is also associated with darker honey, as in this case (^{Escudero et al. 2012}).

The soluble solids content for honey is 75 °Bx according to AOAC-932.12. ^{Pattamayutanon et al. (2015)} reported an average of 81.18 °Bx in a study conducted on honey samples of A. mellifera in Thailand. These values are higher than those recorded in this study, and there was no statistically significant difference by location of sampling sites. The low pH of honey inhibits the presence and growth of microorganisms and allows compatibility of honey with many food products in terms of pH and acidity (^{Silva et al. 2013}). According to a study conducted on A. mellifera honey samples in Cuba, the pH value was 4.76 (^{Alvarez-Suarez et al. 2018}). In honey of the species S. mexicana, the pH was 3.50 to 3.96 (^{Jimenez et al. 2016}). In this study, higher pH values were obtained.

The most prevalent acid in honey is gluconic acid (^{AOAC 1995}), which results from the action of the enzyme glucose oxidase on a glucose molecule. According to ^{Jimenez et al. (2016)}, the value for acidity in honey from the species S. mexicana is 32.90 to 35.10 meq kg^-1. The allowable value for acidity in honey from the species Scaptotrigona is 85.0 meq kg^-1, thus the samples tested are below the maximum allowable value, indicating that they are not very susceptible to fermentation (^{Vit et al. 2013}). Inaddition, it has been noted that the acidity of honey is mportant for preventing the growth of microorganisms (^{Lage et al. 2012}). The lactic acidity (lactone) values in this study were greater than those reported by ^{Bergamo et al. (2019)} in honey of A. mellifera (2.18 and 13.61 meq kg^-1). In Heterotrigona itama honey from Malaysia, values between 129.2 and 144.4 meq kg^-1 have been reported for this indicator (^{Kek et al. 2018}). Comparatively, these values are higher tan those recorded in this study.

The honeys analyzed from the different municipalities have important physicochemical differences, depending on the place and the year of sampling, and these results can be compared with other studies to contribute to the development of a specific standard for determining the quality of this honey.