Characteristics and nutritional properties - 2nd part
Salting is a crucial phase in the process because the amount of salt used has to guarantee both an adequate preservation (by inactivating or delaying any microbial growth) and a pleasant flavour.
The salt must also penetrate the mass of muscle as evenly as possible.
Numerous chemical reactions take place during the curing process, due to mainly proteolytic microbial flora that gradually reduce the dimensions of the proteins, progressively making the meat extremely easy to digest. Here again, this is a very delicate phase because any excessive microbial proliferation could facilitate unwanted reactions, such as acid fermentation (caused by acidifying microorganisms), the production of dextrans by lactobacilli (lending the meat a viscous texture), or the excessive proliferation of moulds or aerobic microorganisms (responsible for swelling, putrefaction, etc). The curing environment itself can also be responsible for excessive moulding, over-dehydration or colonisation of the meat by insects and mites.
The penetration of the salt, the evaporation of the water, and the variations in acidity that take place during the curing process give rise to a slow selection of the microbial flora that leads to the proliferation of lactobacilli and Micrococcaceae capable of determining the final sensory characteristics of the prosciutto.
The highly-qualified Italian prosciutto producers can generally guarantee a product of excellent quality and the genuinity of many Italian prosciutti is protected at European community level. The products with a Protected Denomination of Origin (PDO) are the jambon de bosses Valle d’Aosta (from the municipalities of St. Rhemy and Bosses in the Alta Valle d’Aosta); the prosciutto di Carpegna (in the province of Pesaro); the prosciutto di Modena (in the province of Modena); the prosciutto di Parma (in the province of Parma); the prosciutto di San Daniele (from San Daniele del Friuli and Spilimbergo); the prosciutto toscano (from Tuscany); the prosciutto veneto berico-euganeo (from the hills in the provinces of Vicenza and Padova). The prosciutto di Norcia (from the province of Terni) is a product with a Protected Geographical Indication (PGI).
Once the curing process has been completed, the sensory characteristics of a prosciutto are the outcome of the different strategies adopted in its production, which can consequently give rise to quite different nutritional profiles. A global nutritional picture can be drawn, however, highlighting the following aspects.
(1) Prosciutto crudo has a high protein content, coming between 25% and 30% of the edible portion.
(2) It is also high in protein quality, deriving from its composition in essential amino acids (i.e. the single protein components that the human body is unable to produce in quantities large enough to meet its needs and must introduce with the diet).
The amino acid spectrum accounts for a mean 45% of essential amino acids in the total protein content. There is also a fair amount of arginine (from which growth hormones derive), and branched chain amino acids (lycine, leucine, isoleucine), which are particularly important in the diets of sportspeople.
(3) The average quantity of fats is around 20%, but is considerably reduced when the visible fat is removed from the prosciutto.
The meat’s energy value consequently varies, per 100 g of product, from more than 300 kcal to just below 150 kcal.
(4) As for the quality of the fat, thanks to the combined effects of genetics, nutrition and breeding methods, prosciutto crudo now contains fewer saturated fatty acids, larger proportions of oleic and stearic acids (which have little atherogenic significance), and more unsaturated fatty acids and vitamin E, which is needed to protect them against oxidation. The prosciutto shows a clear boundary between the structural and the depot fats (lard, bacon, etc) and its cholesterol content is remarkably low, averaging around 80 mg per 100 g (and, in lean prosciutto
crudo, a mere 30 mg per 100 g).
(5) The content in vitamins B1, B2 and B12, which are fundamental to energy metabolism, erythrocyte synthesis, nucleic acid formation, and nervous system function, is quite high.
Prosciutto crudo also contains an appreciable amount of carnitine, needed to exploit the energy resource in the fatty acids.
(6) The most represented minerals are sodium, iron, zinc and selenium. Sodium participates in regulating the body’s acid-alkaline balance, it is indispensable for maintaining the osmotic pressure of the body fluids, protecting against any excessive loss of fluids, and regulating muscle excitability and cell permeability. An excessive amount of sodium has been correlated with hypertensive cardiovascular diseases, however.
Iron, a component of haemoglobin, myoglobin and various enzymes, has a fundamental role in tissue oxygenation and numerous chemical processes. Zinc is involved in the metabolism of proteins, genetic material and mucopolysaccharides, in addition to activating numerous enzymes. Selenium is a component of glutathione-peroxidase; it has an important antioxidant role at cell level and is fundamental to male fertility. The iron and selenium contained in prosciutto crudo are in a highly bio-available chemical form, unlike the minerals contained in
vegetable food sources.
Thanks to its nutritional value, prosciutto crudo can be a precious contribution to the diet. On the other hand, it can contribute
to a far from recommendable food overload if it is included too often in the already over-rich diet of a sedentary person with high blood cholesterol levels. The consumption of prosciutto crudo must also be suitably limited in certain medical conditions, e.g. hypertension and renal diseases (because of its high sodium content), and in hyperuricaemia and gout, which benefit from a low-protein diet to minimise the availability of the amino acids useful to purine synthesis.
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