Following a request from the European Commission, the Panel on Biological Hazards (BIOHAZ) of the European Food Safety Authority (EFSA) was asked to deliver a scientific opinion on the public health risks related to mechanically separated meat (MSM) derived from poultry and swine.
Mechanically separated meat as defined in Regulation (EC) No 853/2004 is obtained by removing meat from flesh-bearing bones after boning or from poultry carcasses, using mechanical means and resulting in the loss or modification of the muscle fibre structure. Based on the current EU Regulation, low and high pressure MSM products are defined according to the alteration of bone structure and calcium content. The EU upper limit for low pressure MSM is 100 mg/100 g (1000 ppm) calcium. MSM with calcium concentration above this threshold is considered to be high pressure MSM. Different interpretations of the definition of MSM has led to low pressure MSM products being considered as meat preparations by some Member States.
Therefore EFSA was asked to issue a scientific opinion on the public health risks related to different types of MSM (high and low pressure) with a focus on low pressure MSM made with new production methods and, in particular, i) to identify the public health risks linked to the different types of MSM and compare them as well with fresh meat, minced meat and meat preparations, as defined in EU legislation; ii) to identify and rank the parameters (e.g. muscle fibre modification, calcium content, water activity) that may be used to distinguish between the different types of MSM and compare them as well with fresh meat, minced meat and meat preparations, as defined in EU legislation; iii) to establish the values for such parameters; and, iv) to propose objective methods (not subject to different interpretation) to measure such parameters.
Concerning public health risks related to MSM, the microbial hazards that may be present in MSM depend on the hygiene of processing, the levels and types of contamination present in the raw materials and their storage history, so microbial hazards in pork and poultry MSM are expected to be similar to those in fresh meat, minced meat and meat preparations. Nevertheless the risk of microbial growth increases with the degree of muscle fibre degradation and the associated release of nutrients and more uniform spreading of contamination, thus high pressure MSM may provide a more favourable substrate for bacterial growth compared with low pressure MSM.
For distinction between the different types of MSM and their comparison with non-MSM (fresh meat, minced meat and meat preparations) chemical, histological, molecular, textural and rheological parameters were considered as potential indicators.
Chemical parameters include calcium, phosphate, ash, iron, lipid (including cholesterol) and fatty acids (including those originating from bone marrow), moisture or water content, and protein (including collagen). The analysis of available data derived from published studies, albeit not specifically designed for this purpose, suggested that calcium content was the only appropriate chemical parameter that could be used to distinguish MSM from non-MSM products. Low pressure MSM contains fewer bone particles than high pressure MSM and consequently lower calcium content. Therefore calcium content alone does not allow differentiation between low pressure MSM and other meat products. The method specifically standardised for calcium determination in MSM is a titration method of the acid digested MSM using ethylene diamine tetra-acetate (EDTA), but any method providing validated results could be used.
Cholesterol content could be also useful for discrimination of MSM from non-MSM but this should be confirmed by additional data obtained by standardised methods. For other chemical parameters (protein, ash and iron) statistically significant differences were observed between MSM and non-MSM, however, the discriminatory power was very low due to overlapping data.
Histological parameters considered include microscopic detection of muscle, connective and adipose tissues, bone particles, cartilage, bone marrow and tissue from central nervous system, and their structural changes. Among these, the microscopic examination of tissue structure changes is a promising method for distinction between MSM types and non- MSM, but further validation is needed and objective threshold values are not yet available. Among the microscopy-based methods, the detection of bone particles indicated the presence of MSM, but not all types of MSM contain bone particles. Therefore, bone particle detection may not be used alone to consistently distinguish between MSM and non-MSM. Other histological parameters related to tissue composition (muscle, connective tissue, adipose tissue, cartilage, bone marrow, central nervous tissue) do not provide clear differentiation between MSM and non-MSM.
Molecular parameters were also considered, including assays based on proteomics, metabolomics, electrophoretic techniques and immunological methods, although validation of these methods is incomplete and their cost and complexity may limit their application.
Textural and rheological properties were not considered useful to discriminate different types of MSM from fresh meat, minced meat, and meat preparations because the analysis should be carried out on products with homogeneous structure rather than on particle-reduced products such as minced meat or low pressure MSM.
A binary logistic model was developed in order to derive probability values for a product to be classified as hand deboned meat or MSM based on the calcium content. Calcium contents of 21, 39, 81.5 and 100 mg/100 g correspond to probabilities of 10%, 50%, 90% and 93.6% for a product to be classified as MSM. The distinction of low pressure MSM from non-MSM products would need to be confirmed by the addition of other validated tests for parameters such as cholesterol content and microscopic detection of muscle fibre damage.
The BIOHAZ Panel recommends that, based on changes in processing and properties of derived MSM products, the classification of raw meat recovered after deboning should be based on certain parameters of the final products, such as calcium content. New terminologies may be needed for low and high pressure MSM, because technological advances have resulted in low pressure products resembling minced meat.
It is further recommended that, in order to improve methods for MSM identification, specifically designed studies for the collection of data obtained by standardised methods on potential indicators, especially calcium and cholesterol, should be undertaken. Additional analysis in these studies could include histological examination.
Finally, it is advised that studies on differentiation of MSM from other meat products based on the analysis of combination of different parameters (chemical, physical, etc.) should also be undertaken.