Alimentación universitaria: aspectos nutricionales, microbiológicos y toxicológicos

Abstract

En las últimas décadas la restauración colectiva universitaria ha adquirido gran importancia. Es importante garantizar la calidad y variedad de los menús desde un aspecto nutricional como microbiológico o toxicológico. El control del nivel de compuestos polares en aceites y grasas usados es una medida de prevención frente a tóxicos de origen químico. El estudio de la prevalencia de Anisakis simplex en muestras de pescado es una medida para garantizar la seguridad alimentaria. Los servicios de restauración deben cumplir determinadas normas de higiene para la elaboración, distribución y comercio de comidas preparadas con la finalidad de mantener una calidad microbiológica adecuada. El riesgo producido por la presencia de microorganismos en los alimentos no viene representado únicamente por las bacterias presentes sino, también por las toxinas bacterianas. Entre ellas merecen especial atención las de E. coli y S. aureus. E. coli es una bacteria frecuentemente asociada con toxiinfecciones e intoxicaciones alimentarias. En condiciones normales, constituye una parte esencial de la flora bacteriana humana, sin embargo, existen cepas capaces de provocar alteraciones graves en forma de enteritis. Este grupo de cepas se denomina E. coli enterotoxigénico (ETEC) y se transmiten a través de los alimentos o el agua contaminada por heces animales o humanas. La toxina termo-lábil (HLT) es su principal factor de virulencia. S. aureus es la bacteria enterotoxigénica más corriente de los alimentos. Las cepas toxigénicas de S. aureus pueden producir más de una enterotoxina aunque la enterotoxina del tipo A es la que con más frecuencia aparece en los brotes de intoxicación alimentaria, seguida de los tipos B y D. Merece especial atención la toxina 1 del síndrome del shock tóxico (TSST-1). El desarrollo de técnicas rápidas y selectivas para la identificación y cuantificación de toxinas bacterianas contribuirá a garantizar la seguridad alimentaria.

The catering service at university has become very important in all developed countries in recent decades. Consumers are increasingly demanding healthy and safe food, with better nutritional properties. Meals served must ensure the nutritional quality and limit the exposure to different contaminants that can be found in food. It is therefore important to ensure the quality and variety of menus offered daily, from a nutritional viewpoint as microbiological or toxicological. University students have a special interest because many of them assume, for the first time, responsibility for their meal. Dietary habits established by university students when they are away from home, can have a significant effect on their health, determining or modifying the risk of nutrition-related diseases. In addition to the nutritional hazards it is desirable to identify, assess and prevent hazards from physical, chemical or biological origin that can affect food safety, in order to implement appropriate measures to reduce or eliminate hazards to acceptable health standards. University restaurants are catering services, where transformation of food is done to serve customers. The food served must have adequate sanitary and organoleptic quality, it is also important to safeguard the safety, as these foods may be responsible for food poisoning. Monitoring of polar compounds (legislated in Spain) in oils and fats used is a preventive measure against toxic chemical hazards. These are compounds formed in used oils as a result of changes in fats and oils during frying processes. The presence of external substances with biological origin in foods can also be cause of foodborne disease (FBD). Products consumed in university establishments can be vectors of several biological contaminants, mainly parasites and bacteria. It is therefore important to have systematic monitoring of the microbiological quality of the food served. A large number of marine and freshwater fish can serve as a source of medically important parasitic zoonoses. The most important of the fish-borne helminthes are anisakid nematodes (particularly Anisakis simplex). On the other hand, restaurants must meet certain hygiene standards for production, distribution and trade of ready meals in order to assess the quality and microbiological safety of food. The toxicological hazard caused by the presence of microorganisms in food is not represented only by bacteria present in food; but also bacterial toxins in foods eaten are important. Among them deserve particular attention for E. coli and S. aureus toxins. E. coli is a bacteria often associated with outbreaks and food poisoning. Under normal conditions, constitutes an essential part of human bacterial flora, however, there are strains capable of causing serious diseases as enteritis. This group of strains is called enterotoxigenic E. coli (ETEC) and is transmitted through food or contaminated water by animal or human feces. ETEC labile toxin (LT) is the major virulence factor of ETEC. S. aureus is the most common toxigenic bacteria in food. It is responsible for most annual cases of food poisoning caused by ingestion of foods where enterotoxins have been preformed. Toxigenic strains of S. aureus can produce more than one enterotoxin although enterotoxin type A is the most frequently found in outbreaks, followed by types B and D. S. aureus produce also toxic shock syndrome toxin 1 (TSST-1), previously classified as enterotoxin F, which has not been extensively studied in restaurants. The development of rapid and effective techniques for enterotoxin isolation and identification represent a great advantage for the evaluation of its toxicity and to quantify the amount of toxin produced by strains isolated from food. This will contribute to food security and thereby safeguard consumers´ health in university restaurants.