Pregnancy and toxoplasmosis. Why eating dry cured ham appear to be safe.

During pregnancy future mums need to follow a suitable diet. This simply means a varied diet including: milk and dairy products, meat, fish, eggs, pulses, cereals and cereal products, fruit and vegetables, and olive oil. A number of precautions have to be taken, such as avoiding the consumption of raw or undercooked meat or fish, as well as salamis, to prevent the risk of acquiring dangerous intestinal infections or toxoplasmosis, an infection which can cause serious harm to the unborn child if acquired by women who are not immune during the early stages of pregnancy.

Toxoplasma gondii is a protozoan which generally lives in the intestines of cats, which become infected by consuming small rodents.

Cats provide a breeding ground for this microorganism, since cats’ intestines are the perfect environment for the sexual reproduction cycle of toxoplasma. The oocysts are expelled in the cat’s faeces and may be ingested by other animals or humans, which act as its intermediate hosts. Toxoplasmosis is a typical syndrome affecting pets.

In man, toxoplasmosis manifests itself in a number of different ways, such as asymptomatic infections and encephalitis. It can produce serious complications in pregnant women, including miscarriage, premature labour and neonatal mortality. Congenital toxoplasmosis (transmitted via the placenta) derives from an acute primary infection of the mother during pregnancy or just before (infection at least six months before becoming pregnant makes it unlikely that the unborn child will be infected). The severity and incidence depend on the trimester of pregnancy.

Toxoplasmosis is one of the commonest infections in the world: it is more common in warm temperate zones at low altitude and less common in cold climates and mountainous regions.

The disease can be acquired in different ways: through the accidental ingestion of oocysts expelled by cats and matured in the external environment (when handling earth and cat litter, contact with anything that has been in contact with cat faeces); eating poorly washed raw vegetables; eating raw or undercooked meats (especially pork, lamb and game), fresh sausages or insufficiently aged salamis and unpasteurised dairy products contaminated by oocysts; accidental ingestion of cysts through contact between the mouth and hands which have handled raw meats. Prolonged refrigeration and freezing, as well as heat (60°C for 20 minutes or 70°C for 10 minutes) remove oocysts from foods. Meat-based products aged for more than 2 months appear to be safe. Dry cured hams, such as Prosciutto di San Daniele, Prosciutto di Parma, Prosciutto di Veneto Berico Euganeo and others should be considered safe since they are salted and matured for over 13 months. Salt, dehydrations (Aw < 0.92) and aging over a long period (more than 13 months) seem to deactivate any oocysts present in the muscles, as demonstrated by numerous international articles.

 

Bibliography:

www.dpd.cdc.gov; www.cdc.gov

Bayarri S, Gracia MJ, Pérez-Arquillué C, Lázaro R, Herrera A. (2012) Toxoplasma gondii in commercially available pork meat and cured ham: a contribution to risk assessment for consumers. J. Food Protect. 5(3):597-600.Bayarri S, Gracia MJ, Lázaro R, Pe Rez-Arquillué C, Barberán M, Herrera A. (2010) Determination of the viability of Toxoplasma gondii in cured ham using bioassay: influence of technological processing and food safety implications. J. Food Protect. 73(12):2239-43.

 

Prof. Giuseppe Comi

Can coeliacs eat dry-cured ham?

Gluten intolerance seems to be becoming increasingly widespread, therefore raising questions amongst those who are diagnosed with this intolerance as to whether dry-cured ham is one of the products to be avoided.

We asked the Associazione Italiana Celiachia (AIC – Italian Coeliac Association – http://www.celiachia.it) to give their opinion, an organisation which represents the over 120,000 people diagnosed with coeliac disease in Italy to date (data from the latest Parliamentary Report on coeliac disease). With around 65,000 members, it has been working for over thirty years to promote care for coeliacs, organising important initiatives designed to encourage gluten-free dietary compliance (Food Handbook, Eating Out, dietary education in schools), providing doctors with information about diagnostic and therapeutic possibilities, encouraging scientific research, and raising awareness in political, administrative and healthcare environments. It operates across Italy, through its 20 Regional Associations.

Associazione Italiana Celiachia

Associazione Italiana Celiachia

Over the years, the AIC has achieved a number of important objectives, including the free distribution of gluten-free nutritional/therapeutic products to all those diagnosed with coeliac disease by the Italian National Health Service and the publication of a specific framework law on coeliac disease designed to protect the rights of coeliacs and encourage their normal inclusion in daily life (Italian Law 123/2005).

The Associazione Italiana Celiachia includes dry-cured ham amongst the allowed food types, which can therefore be freely consumed by coeliacs.

In fact, the introduction to the AIC Food Handbook states: “dry-cured ham, from which the sugna (pork fat), i.e. the whitish yellow layer not covered by the rind, must be carefully removed, is the only risk-free cold cut.

In fact the sugna normally consists of fat, salt and flour (rice flour in 75% of cases). It is removed completely before slicing the product and, moreover, even if the flour used happened to be wheat flour, there is no possibility of gluten penetrating or migrating into the edible part of the dry-cured ham.”

Ham quality: the Tyrosine’s role.

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The quality of dry-cured ham is achieved by controlling chemical parameters, such as the salt (NaCl) concentration, humidity and the cialis super active proteolysis index. Proteolysis has an effect on the digestibility, the texture, the colour and the frequently observed white surface sheen of the dry-cured ham, as well as the precipitation of tyrosine crystals*.

In fact, it is often the case that when a well-aged, dry-cured ham is cut, whitish, chalky-looking formations can be observed, consisting of amino acids deriving from the proteolysis caused by meat proteases*. More specifically, they consist of tyrosine and, to a lesser extent, phenylalanine* and other amino acids. The origin of these formations is still controversial and various different theories are still being explored. Table 1 shows the most important and most reliable of these. Proteolysis by tissue enzymes seems to be the most reliable.

In fact, meat enzymes, also known as cathepsins, act on the denatured muscle proteins resulting in the release of peptides* and amino acids, including tyrosine and phenylalanine.

Due to the low water solubility , the pH (degree of acidity) and the aw* (water activity) of dry-cured ham, these then precipitate and crystallise to produce the well-known “tyrosine crystals”. The theory regarding the production of tyrosine due to bacterial activity (proteolysis or synthesis), despite being supported by the available evidence, is not very reliable. In fact, bacterial activity in dry-cured ham is only superficial as few bacteria are present in the muscle and their metabolism is limited by the salt. In other words, the concentration of tyrosine in the granules cannot be justified by bacterial activity alone.

Therefore, tyrosine production primarily derives from the activity of cathepsins*. From the very start of the aging process, they break down the proteins and begin by releasing peptides (chains of amino acids). Later on, the peptides are broken down into amino acids which, depending on their degree of solubility, precipitate to form granules. The same white surface sheen, which is sometimes found on the cut surface of dry-cured ham, is not formed by salt but by amino acids.

Cutting dry-cured ham

Cutting dry-cured ham

The presence of granules is often considered to be a defect. The texture of the resulting dry-cured ham is not as good as that of a dry-cured ham without the granules: it seems softer. Moreover, the quantity of free nitrogenous fragments (amino acids) may give the dry-cured ham a bitter and metallic taste, compromising its organoleptic properties. However, in my opinion, if we ignore the sensation of chewing “chalk”, the product has a high proteolysis index and is therefore more digestible, because it contains many free amino acids which are easily digested by the body.
Table 1: Theories regarding the formation of tyrosine crystals

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a)     proteolysis by tissue enzymes

b)    proteolysis by microbial enzymes

c)     microbial amino acid synthesis

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aw: Water activity: free water, used by bacteria or enzymes in order to carry out their functions. The lower it is (due to added salt or molecules that bind water), the less active the enzymes and bacteria.

Proteolysis index: soluble nitrogen/total nitrogen ratio (e.g. soluble nitrogen – amino acids / total nitrogen – proteins + amino acids).

Precipitation of tyrosine crystals: tyrosine amino acid is not very soluble in water, meaning that it accumulates and forms crystals or granules. For example, if we added sand to a glass of water it would not dissolve, but instead would precipitate to the bottom, and the same thing would happen if we added tyrosine to water.

Meat proteases (cathepsins): these enzymes break down proteins (chains of amino acids) resulting in the release of individual amino acids or peptides (small chains of amino acids).

Phenylalanine: an amino acid found in proteins.

Peptides: chains of amino acids (from 2 to 12 and more amino acids).

Cathepsins: meat proteases that break down proteins and turn them into peptides and individual amino acids. They break apart proteins (chains of amino acids) resulting in the release of peptides and individual amino acids.

Fats inside dry cured ham

Dry cured ham is the leading product in the Italian charcuterie industry, both with respect to tradition and organoleptic properties. As a meat-based product, it is made up of 2 components: the lean part consisting of the thigh muscles, and the fatty part, consisting of the adipose fat (covering the meat and under the rind), and the muscular fat (intramuscular, marbling and intermuscular).

The percentage of fat varies according to the breed, the genetics and the diet of the pig, accounting for between 11 and 18 per cent of the edible part of the ham.

Fat has a high nutritional value, because it is made up of saturated fatty acids*1, monounsaturated fatty acids*2 and polyunsaturated fatty acids*2.

The latter are fundamental to human health and are similar to those contained in vegetable oils (olive and seed oils) and in fish (omega-3 and omega-6). A 50 g portion of Prosciutto di San Daniele can contain as much alpha-linolenic acid (omega-3) as 100 g of salmon.  Moreover, the fat in ham contains essential fatty acids such as linoleic acid*3 (omega-6), arachidonic acid*4 (omega-6), and alpha-linolenic acid*5 (omega-3). From these acids, humans are able to synthesise all other polyunsaturated fatty acids, essential precursors in biological membranes,  the development of the nervous system, growth, immune defence, fighting cancer and regulating blood cholesterol levels. Consequently, these fatty acids help to prevent hardening of the arteries (arteriosclerosis). Contradictory to what was believed previously, dry cured ham contains a low percentage of cholesterol (max. 33 mg/100 g of the edible part). This percentage is lower than that found in some fish (sea bass) and shellfish. Furthermore, on the basis of these considerations (low cholesterol concentration, higher percentage of unsaturated fatty acids than saturated fatty acids, presence of omega-3 and omega-6 fatty acids), nutritionists and health experts have, just recently, extensively re-evaluated the consumption of pork, and dry cured ham in particular.  They finally realised (it was about time) that dry cured ham is a food suitable for everyone, and that its lean/fatty component is fundamental to physical and mental wellbeing in children, adolescents, adults and the elderly.

Table. Percentage of fatty acids in the fat of dry cured ham

Table. Percentage of fatty acids in the fat of dry cured ham

Notes

1. Saturated fatty acids consist of a saturated carbon chain comprised solely of single C-C bonds. Saturated fatty acids, along with monounsaturated or polyunsaturated omega-6 fatty acids reduce LDL cholesterol (“bad cholesterol”).

2. Unsaturated fatty acids are characterised by one or more double bonds in the carbon chain. They are usually found in liquid form, and are contained in olive oil (rich in monounsaturated fatty acids, that is with just one double bond) and seed oil (rich in mono and polyunsaturated fatty acids, with two or more double bonds). Like linoleic acid and monounsaturated fatty acids, unsaturated fatty acids actually increase HDL cholesterol (“good cholesterol”) levels, which in turn increases the removal of triglycerides from the bloodstream. Of all the polyunsaturated fatty acids, a particularly important role is played by the long-chain omega-3 fatty acids, which are primarily found in fish oils. Consumption of a balanced ratio of omega-3/omega-6 is very beneficial to humans. In fact there is evidence, albeit inconclusive, to support the theory that these fatty acids protect against fatal heart disease.

3. Linoleic acid is one of the essential fatty acids and belongs to the omega-6 group. Linoleic acid is found in all vegetable oils and is abundant in many of them, particularly safflower oil and sunflower oil, but also, to a lesser extent, in corn oil, soya bean oil, green coffee and others. It is also found in some animal fats.

4. The arachidonic acid found in the human body is introduced through the diet or derives from linoleic acid (essential fatty acid).

5. Alpha-linolenic acid (omega-3) is one of two essential fatty acids that humans and other animals need to consume in their diet in order to maintain a good state of health. This is because the body requires this fatty acid for various biological processes, and also because it cannot be synthesised endogenously, but needs to be absorbed through the diet.

 

Prosciutto Veneto Berico-Euganeo PDO finds its way to the Vatican

Gian Antonio Visentin, re-confirmed President of the Consorzio di Tutela del Prosciutto Veneto Berico-Euganeo (Consortium of the Prosciutto Veneto Berico-Euganeo) for the three-year period from 2011-2013, has summed up the positive period for sales of Veneto Berico-Euganeo PDO (Veneto dry-cured ham) for the magazine Premiata Salumeria Italiana (issue 4/11).

Marchiatura a fuoco Prosciutto Veneto - Berico Euganeo

Branding of Prosciutto Veneto - Berico Euganeo

Comparing 2010 sales figures (90,000 pieces) with 2005 sales figures (55,000 pieces), there has been a clear increase in production due to the increase in demand.

Veneto Berico-Euganeo PDO is known by more and more consumers, thanks in part to the work of the Consortium, which has focused on and invested in marketing, advertising and an increased participation in trade fairs.

According to Visentin, the first few months of 2011 were very positive, inasmuch as the demand actually exceeded the production capacity, with this growth affecting all eleven members of the Consortium.

A dry-cured ham appreciated by all: “Our dry-cured ham has even found its way to the Vatican,” concludes the President of the Consortium of the Prosciutto Veneto Berico-Euganeo PDO.