Introduction

Gastronomy is important because it creates links between people and the places they visit; thus, besides being a cultural manifestation, it can also be a tourist resource (^{Ricolfe et al., 2008}). Although there is interest from tourists to consume traditional cuisine representative of the attended places, sometimes this local food consumption is avoided because it is unfamiliar and hygiene during its processing seems inadequate (^{Amuquandoh, 2011}).

In some developing countries, it is common to prepare food with poor hygiene and sanitation, so that tourists may suffer gastrointestinal disorders, such as traveler's diarrhea. In this regard, the Centers of Disease Control and Prevention reported in 2006 that traveler's diarrhea affects every year between 20 and 50 % of the international travelers, and that the higher-risk destinations are developing countries from Latin America, Africa, Middle East and Asia (^{CDC, 2006}).

Some foodborne diseases (ETA's) are: salmonellosis, shigellosis and listeriosis. In the literature there are documents about the presence of pathogen microorganisms in both, the staff and the foods sold in tourist destinations. In this regard, a study carried out in Nairobi, Kenya, ^{Onyango et al. (2009)} reported cases of infection by pathogenic Escherichia coli in food handlers working in luxury hotels. This shows the importance of assuring the hygienic quality of food, as it can help strengthen or impair the image of the touristic destiny.

Edible insects are ingredients collected for food in some states of Mexico such as Chiapas (^{Ramos-Elorduy and Pino, 2002}), Oaxaca (^{Ramos-Elorduy et al., 1997}), Hidalgo (^{Ramos-Elorduy et al., 2002}) and the Estado de Mexico (^{Miranda et al., 2011}; ^{Viesca et al., 2012}). In the later, the archaeological and tourist area of San Juan Teotihuacan is a highlight, where "escamoles" (Liometopum apiculatum Mayr, 1870 Hymenoptera Formicidae.), white worms (Aegiale heperiaris, K. Walker, 1856 Lepidoptera: Megathymidae) of agave (Agave salmiana Otto ex Salm-Dick) and red agave worms are used in the production of local cuisine specialties (^{Miranda et al., 2011}) for domestic and foreign tourists.

Red maguey or agave worms are the larva of a moth Comadia redtembacheri Hammershmidt, 1848 Lepidoptera Cossidae. Its Nahuatl name is "Chichitlicocuilin" and it is commonly known as "chinicuil" or "michicuil"; inhabits the "pineapple" (core of the Agave, or "mezontete") of the maguey (Agave spp.). Its length is of about 3-4 cm (^{Granados, 1993}). It is used in the Mexican traditional distilled spirit industry, to flavor it (^{Ramos-Elorduy et al., 2006}). This insect is in great demand throughout the year in the tourist area of San Juan Teotihuacan. It is more abundant in July, August and September and it is commonly offered on markets and restaurants in the area, prepared in butter sauce, roasted, or fried as a snack (^{Miranda et al., 2011}).

In the scientific literature there is significant research on the economic and cultural aspects, taxonomic, chemical and nutritional composition of various insects, including red agave worm (^{Ramos-Elorduy et al., 1984}; Ramos-Elorduy et al., 1988); still, reports on the microbiological quality of edible insects are scarce. ^{Arango et al. (2004)} carried out a microbiological study on Hermetia illuscens L.; whereas larvae flour (Diptera: Stratiomyiidae) in Colombia. ^{Klunder et al. (2012)} did it in flour larvae (Tenebrio molitor Linnaeus, 1758) and crickets (Acheta domesticus Linnaeus, 1758).

Although there is information on the nutritional composition of red maguey worm, its hygienic quality has not been evaluated nor in prepared dishes with this worm, such as those sold in some areas with national and international tourism. The aim of this study was to determine the hygienic quality of some dishes prepared with red agave worm in local food and drink establishments in the tourist area of San Juan Teotihuacan, Estado de Mexico, during the September and November seasons.

Materials and Methods

Results and Discussion

Various insects have high protein content of high biological quality, minerals (^{Ramos-Elorduy et al., 1998}), fiber, vitamins (^{Ramos-Elorduy and Pino, 2001}) as well as their caloric intake can also be high (^{Ramos-Elorduy and Pino, 1990}); their contribution to biodiversity and ecological advantages are important. Therefore, the practice of entomophagy or anthropoentomophagy (consumption of insects or their derivatives by human) (^{Costa-Neto and Ramos-Elorduy, 2006}) may be a factor to promote food security and environmental sustainability in the world (^{Belluco et al., 2013}; ^{Van Huis et al., 2013}). In addition, the consumption of insects is increasing among tourists in the world, especially those interested in ecotourism, which includes experiences that reflect the traditional way of life of the visited communities, including recollection and food preparation (^{Yen et al., 2013}).

According to the Mexican National Institute of Anthropology and History (INAH) in 2011 the archaeological site in Teotihuacan, Mexico, received 2 million 234 439 visitors; 77 % of them were Mexican nationals (^{INHA, 2012}). An unknown number of them consumed local cuisine, which includes culinary specialties prepared with local ingredients, such as edible insects, the red maguey worm among them.

^{Belluco et al. (2013)} suggest that insects can accommodate different pathogenic bacteria and consider that research has been limited to those insects classified as agricultural or livestock pests, such as the darkling beetle (Zoophobas morio) and flies. ^{Klunder et al. (2012)} carried out microbiological analysis in flour larvae (Tenebrio molitor, Linnaeus, 1758) and crickets (Acheta domesticus, Linnaeus, 1758) fresh, boiled, grilled and then stored (refrigerated and room temperature). In fresh insects, enterobacteria and spore forming bacteria were isolated, which were generally from non-pathogenic species. These authors point out that high temperatures reduced the microbial load, mainly from the Enterobacteriaceae family. They also detected spores, which probably came from the ground and were not fully eliminatedeven after boiling, so they suggest that insects should be carefully handled.

Only one study on the microbiological quality of the "Cuchamá" insect (Paradirphia fumosa R. Felder & Rogenhofer, 1874) prepared in flour, which is used for culinary purposes in the Mixteca of Puebla, Mexico (^{Navarro-Cruz et al., 2011}), was found in the literature reviewed. That product showed levels of mesophilic aerobic bacteria, fungi, yeasts and total coliforms of less than 10 CFU g^-1, which was below the limits of the NOM-147-SSA-1996.

The restaurants nearby to the archaeological site of Teotihuacan prepare red maguey worms: 1) fried in butter or oil; 2) cooked with garlic (Allium sativum L. 1753), onion (Allium cepa Alef.), serrano pepers (Capsicum annuum L. 1753), parsley (Petroselinum sativum (Mill) Fuss), epazote (Chenopodium ambrosioides L.) and coriander (Coriandrum sativum L.); 3) roasts and 4) in sauce with tomatoes (Physalis ixocarpa Brot. ex Hornem; 1819), onion, garlic, green serrano peppers and coriander. They are usually offered with refried beans (Phaseolus vulgaris L. 1753), guacamole, nopal (Opuntia spp.) and tortillas (Table 1).

Table 1 Characteristics of foods prepared with red agave worm (Comadia redtembacheri H.) in the turistic area of San Juan Teotihuacan, Mexico. 

The count of indicator organisms in the analyzed samples was based on the Mexican Official Standard NOM-093-SSA1-1994 (Goods and services. Hygiene and sanitation practices in the preparation of food offered in fixed establishments). Although, it is currently dismissed, it was used because the updated version (Mexican Official Standard NOM-251-SSA1-2009; Hygienic practice for food processing, beverages or supplements) does not set a maximum permissible of indicator microorganisms limit in food.

The amount of aerobic mesophilic of the 18 samples from the first assessment was 30-27 000 CFU g^-1, and in the second 15-71 000 CFU g^-1. Aerobic mesophilic values did not exceed the maximum limit (150 000 CFU g^-1) stated in the Mexican Official Standard NOM-093-SSA1-1994.

The number of mesophilic aerobic bacteria could be influenced by the way the food is prepared. Thus, in the first assessment, some samples of fried red worms in oil had a lower microbial count (30200 CFU g^-1) that those fried in butter (330 CFU g^-1). This could be because the temperatures with the oil are greater than in butter. Roasted red worms, without further ingredients, presented between 480 and 2800 CFU g^-1. In this regard, proper food roast depends on the time required for the procedure and the temperatures inside it. In samples prepared with garlic, onion, coriander, epazote, serrano peppers and tomato, the presence of mesophilic aerobic bacteria varied between 150 and 1300 CFU g^-1. The maguey worms fried in oil were expected to have a lower microbial count than those prepared with other ingredients, which could contaminate the samples, but this was not the case. This might be the result of a combination of factors such as the method, time and cooking temperature, the added ingredients and quality of raw materials used in their preparation.

The samples from establishment 4, from the first sampling, were fresh and raw red worms, and in the second were frozen and raw; in those samples the aerobic mesophilic number was of 27 000 and 800 CFU g^-1 in the first and second sampling, respectively. This confirmed that freezing, although not a preservation method intended to destroy microorganisms, does decreased their number. In contrast, samples prepared with frozen red worms did not show lower microbial counts. This might be the result of poor hygiene during food preparation.

During November, mesophilic aerobic bacteria were more abundant. This could be due to inadequate freezing of the worms. The great variability of the results in November may be because there is no standardized methodology for freezing worms used by all restaurateurs (Table 2). In this regard, owners lack techniques, infrastructure and appropriate technology to adequately freeze and store the worms and other goods. The red maguey worms, after being collected, are washed with water to remove soil residues, and then frozen and stored in home freezers. Unlike the freezers used by large super markets and food and beverage franchises, these lack control and strict temperature monitoring.

Table 2 Descriptive statistics of the mesophilic aerobic bacteria count (CFU g^-1) in foods prepared with red agave worm (Comadia redtembacheri H.) sold in the touristic area of San Juan Teotihuacan, Mexico. 

The Wilcoxon signed-ranks test showed no significant statistical difference (p = 0.407) in the presence of aerobic mesophilic between both sampling periods, regardless of the difference between thesamples average. This could be due to the presence of outliers caused by exceptional unidentified situation.

All samples from both seasons were free of total and fecal coliforms. This result shows that the recollection, marketing and product preparation of the food and other raw materials are suitable.

^{Arango et al. (2004)} evaluated the levels of indicator organisms and pathogens in flour of larvae H. illuscens L. (Diptera: Stratiomyiidae) following the Colombian normativity (Colombian ICA Standard No. Dip-30-100-003). They concluded that the flour had acceptable microbiological quality, because the mesophilic aerobic and Clostridium spp. were within the ranges allowed by the norm.

The assessment of yeast and fungi showed higher statistical mean and variability in November than in September (Table 3). The minimum yeast count was 10 in September and November.

Table 3 Descriptive statistics for the number of yeasts (CFU g^-1) and mould in foods made with red agave worm (Comadia redtembacheri H.) sold in the touristic area of San Juan Teotihuacan, Mexico. 

The standard deviation was also higher in the samples obtained in November. The average and maximum count of moulds was higher in the November samples. This could also be associated with the time and storage conditions of the frozen red maguey worms. In this sense, moulds and yeasts can grow in frozen food when stored in inadequate conditions. However, according ^{Orberá (2004)}, the group yeasts that adversely associate with food is low: about 25 % of the identified species, of which only a low percentage might be harmful.

The Wilcoxon signed-ranks test showed no significant statistical difference in the moulds counts (p = 0.180) and yeast (p = 0.225), between the two sampled periods (Table 3).

Conclusions

This study shows that dishes prepared with red agave worm (Comadia redtembacheri H.) sold in the tourist site of San Juan Teotihuacan have an adequate hygienic quality.

The application of appropriate practices during the entire chain of production, collection, preservation, preparation and marketing of the red maguey worm should be maintained or improved to maintain the microbiological quality of the culinary preparations that have brought fame to San Juan Teotihuacan.

Taking care of the microbiological quality of the food offered to the public could help to maintain or increase gastronomic tourism activities in the area.