PROJECT AMBASSADOR OF September 2015
Dr. Mercedes Careche / INSTITUTO DE CIENCIA Y TECNOLOGÍA DE ALIMENTOS Y NUTRICIÓN (ICTAN-CSIC), Spain
Dr. Mercedes Careche is leader of workpackage 7, which deals with the interventions in the food chain to reduce the risks posed by anisakids parasites. This WP is particularly aimed at designing methods, treatments and devices for the inactivation of anisakids and their allergenic capacity in fishery products.
About Mercedes Careche
Dr. Mercedes Careche is Research Professor of the Spanish National Research Council (CSIC). Her research lines include the development of tools for the evaluation and improvement of the quality of seafood, the development of sensory methods and the application of multisensory techniques to evaluate fish quality. Her work is also focused in the elucidation of mechanisms responsible for quality loss in fish muscle, i.e. the relation between the structure, ultrastructure of the muscle and the techno-functional properties and texture attributes. Moreover, she has conducted studies on consumer-oriented design and development of functional seafood products.
Dr. Mercedes Careche has given us some key answers related to her work within the Parasite project:
What does “viability” of anisakids larvae mean? Are all live larvae “viable”?
A viable larva has been defined as being physically intact and motile, as demonstrated by spontaneous movements following stimulating by bending with forceps and a needle. When we use the term viability we are referring to the capacity of a given larva to survive to certain treatments or processing conditions. We find some larvae that may have their cuticle broken but they still show some movement. According to this definition they would not be viable but there could still be considered alive.
And infectivity? Do different anisakids species have different infective capacity?
Infectivity refers to the capacity of the larvae to successfully infecting a human. It is not clear to what extent viable larvae are able to being infective; other methods in addition to the viability test could be examined in order to assess the pathogenic potential of these species. As regards the second question, yes, there may be differences in the pathogenic potential even between different Anisakis simplex sibling species. For example some authors have found that for a given set of viable larvae, Anisakis simplex s.s. larvae have more penetrative power than A. pegreffii, higher ability of survival in artificial gastric juice, and these differences have even proven in animal experimental models which simulate infection in humans.
Currently, which are the main treatments for inactivating anisakids larvae in fishery products? Are they effective?
There is a series of physical treatments that have been studied such as freezing, heating, application of high hydrostatic pressure, irradiation, low voltage current, drying or smoking. Among the chemical treatments, the most studied ones include salting and marinating. In addition, some extracts from vegetable products have been studied for their usefulness for killing these larvae. Freezing and cooking are the reference ones, since when they are correctly performed they can guarantee the mortality of the larvae. Actually, they are included in the EC Regulation for fish products intended to be consumed raw or undercooked. The regulation states that the product should reach -20 °C in all parts of the of the product for not less than 24 h or -35 ºC for not less than 15 h. The regulation also states that for heating a minimum core temperature of 60 ºC during at least 1 min is sufficient to kill the larvae.
Within the PARASITE project, some of these methods are being improved. Which are their main advantages?
Many of these treatments are being assayed within the project, but we have mostly concentrated on optimizing the freezing and heating treatments, since EC regulation covers in fact a wide range of technological conditions and we can expect high differences in fish quality depending on how these treatments are applied. Anisakis larvae have shown to be moderately freezing and heat tolerant and therefore it is important to define at which point the parasites are no longer infective, since a too short treatment may lead to health problems, but too extensive treatments may cause substantial economic losses in the industry as well as quality problems to the consumers. In addition, little information is available on factors such as how different species of larvae tolerate these treatments or other intrinsic factors that may affect the susceptibility of larvae to these treatments. Moreover, we are analysing the effect of these factors on the allergens recognition since there are scarce data about how these treatments are affecting allergenicity.
Are those treatments effective for eliminating anisakids antigens/allergens also?
They are not and in order to reduce or inactivate the allergenic capacity, specific strategies need to be designed. In the project, different treatments are being applied (thermal, washing, cryoprotectants) and their effect on the allergen recognition is being studied in some final or intermediate fishery products such as canned fish, surimi, and gels. According to the results obtained so far, it can be concluded that the decrease in the allergenicity observed after some of the assayed operations opens a possibility of using muscle infected with Anisakis larvae in elaborated products.