R. Chizzolini

Calorific value and cholesterol content of normal and low-fat meat and meat products

Abstract This review deals with the topic of fat and cholesterol intakes derived from the consumption of meat and meat products and the impact that the development of low-fat products might have. The relationships between fat and cholesterol intake and blood cholesterol levels are discussed in the light of the most recent findings. The calorific value and the cholesterol content and, therefore, the relative dietary contribution of meats are discussed in relation to animal species, type of muscle and main representative products. The relationship between fat and cholesterol content in meat is thoroughly examined. The lowering of fat content in fresh meat and in meat products is analysed in relation to the proposed aim of reducing calorific value and, possibly, the amount of cholesterol. The effect of cooking is also reviewed. Some final comments are devoted to the oxidative hypothesis of chronic cardiovascular diseases.

Volatile compounds of commercial Milano salami.

The relationship between extracted volatiles of Milano salami, one of the main dry-cured sausages produced in Italy, and their olfactory properties was studied. Volatile compounds were extracted by a purge-and-trap method, quantified using a flame ionisation detector and identified by mass spectrometry. Olfactory analysis was performed by sniffing the gas chromatographic effluent. Nearly 80 compounds were identified and quantified: most came from spices (60.5%), 18.9% from lipid oxidation, 11.8% from amino acid catabolism and 4.9% from fermentation processes. Panellists detected 19 odours by sniffing. These odours were associated with spices, lipid oxidation or fermentation and were in agreement with the contributions of each reaction to the overall aroma of the product.

Oxidation in traditional mediterranean meat products

Lipid oxidation in dry-fermented sausages and dry-salted-hams, representative items of traditional Mediterranean pork products, is responsible for the production of compounds which can affect their organoleptic qualities and wholesomeness. Lipid-derived compounds make up an important share of the volatiles extracted from matured products, once the contribution of spices is removed, and contribute significantly to the flavour of old style products. The few reports available on oxysterols depict a total cholesterol oxidation rate of about 0.1%, a threshold level for toxic effects to occurin vitro but about 100 times lower of thein vivo toxicity dose. The value could perhaps be reduced with the use of antioxidants. Phospholipids are the main class of fats interested by lipolysis and unsaturated fatty acids are those most interested by oxidation. On that basis, the case of special feeding regimes, such as that of Iberian pigs, and the possible relevance of muscle fibre type on flavour development are discussed.

Lipolysis and lipid oxidation in fermented sausages depending on different processing conditions and different antioxidants.

Lipolysis and lipid oxidation in Mediterranean and North Europe type sausages were studied in relation to raw material, processing conditions and additives. In particular the effect of ascorbic acid, nitrites and spices was evaluated. Lipolysis was measured by the determination of total and free fatty acids of fresh minces and matured products and lipid oxidation was evaluated by thiobarbituric acid reactive substances and cholesterol oxidation products. The increase of free fatty acids during maturation appears to be independent from processing conditions and the differences in polyunsaturated fatty acids increment found among the formulations appear to be due to inherent variations of raw materials. The presence of ascorbic acid and/or nitrite seems important for cholesterol protection and, as a consequence, for the safety of fermented meat products while spices at doses up to 0.1% do not seem to have a remarkable effect. The effect on fatty acid oxidation of the same additives and of the different processing technologies is not significantly different and the variations linked to raw material may play the greatest role.

Lipid and cholesterol oxidation in frozen stored pork, salame Milano and mortadella.

An investigation has been carried out on oxidative processes of fresh and stored frozen pork and of two pork products (salame Milano and mortadella). Wholesale pork cuts (shoulder, ham trimmings, belly and backfat) were checked fresh and after frozen storage (1, 3 and 6 months). The streaky bacon was studied fresh and after scalding at 80 °C. Salame Milano and mortadella were produced with fresh and frozen raw materials and a few commercial samples were also part of the study. No real differences have been observed between commercial and experimentally produced salame and mortadella. Peroxide and TBARS values were low in all cases. Among the cholesterol oxides determined (7β-hydroxycholesterol, 5,6α-epoxycholesterol, 7-ketocholesterol and 25-hydroxycholesterol) those dangerous for human health were either absent or their concentration was below toxic levels. The results are discussed on the light of literature reports and Italian pork products technologies.

Lipid and colour stability of Milano-type sausages: effect of packing conditions

Lipid and colour oxidative changes in Milano-type fermented sausages were studied in relation to packing conditions and extended storage under fluorescent light. Matured sausages were sliced and packed under vacuum or in protective atmosphere (100% N(2)) and exposed in a display cabinet to mimic commercial conditions of light and temperature for 2 months. Lipid oxidation was measured by the determination of thiobarbituric acid reactive substances (TBARS) and cholesterol oxidation products (COP), whereas the oxidation of nitrosylmyoglobin was evaluated by a trained sensory panel. Lipid oxidation and discolouration were positively related in vacuum-packed sausages: TBARS and COP values increased significantly concurrently with increasing brown scores. Protective atmosphere came out to be more efficient than vacuum in controlling fatty acid oxidation and, to a lesser extent, cholesterol and pigment degradation: TBARS values remained constant during the whole storage period whereas cholesterol oxides and brown colour scores gradually increased but remained lower than those of vacuum-packed sausages. Higher residual oxygen in vacuum packing could be responsible for the observed differences in oxidative stability.

Oxidative stability of lipids and cholesterol in salame Milano, coppa and Parma ham: dietary supplementation with vitamin E and oleic acid

An investigation has been carried out on the effect of dietary supplementation with vitamin E and oleic acid on oxidative stability of Italian representative pork products. Fatty acid composition of deposited fat was modified in the oil supplemented groups with negative effects on fat firmness. Oil supplementation significantly increased vitamin E content of muscles, as well. Oxidative stability of fat, evaluated by TBARS and cholesterol oxides, has not shown significant differences between dietary treatments but, although the differences were not significant, the tendency was sufficiently clear, especially in salame Milano, towards a lower oxidation level in vitamin E enriched meat. Cholesterol oxidation was found to vary in general around 0.1% of total cholesterol and the only cholesterol oxides observed were 7β-hydroxycholesterol, 5,6α-epoxycholesterol and 7-ketocholesterol. Aldehydes content and distribution appeared to be linked, firstly, to the specific processing technology of the product and, secondly, to the changed fatty acid composition.

Comparative evaluation of some antioxidants in salame Milano and mortadella production.

Six formulations of salame Milano and mortadella were produced, one without antioxidants, two with sodium ascorbate (0.05-0.1 and O.2%), one with catechin, one with phytic acid, and one with sesamol. The products were studied for oxidation levels (peroxide value, TBARS, cholesterol oxides) and colour stability. The evaluation of the latter took place in conditions simulating commercial types of packaging (vacuum and modified atmosphere) and display. A significant difference emerged in colour stability. With the exception of salame Milano packed under modified atmosphere, in all cases salame and mortadella produced without Na ascorbate had significantly lower colour stability. Both in salame and mortadella, peroxide values and TBARS determination gave indications of a possible pro-oxidant effect of ascorbate 0.2% compared with an effective antioxidant activity of the other compounds tested. Cholesterol oxidation in salame appeared to be inhibited by sesamol and ascorbate while catechin was much less effective. In mortadella the prooxidant effect of Na ascorbate was confirmed. All lipid oxidation parameters, though, showed low oxidation values so that no quality nor health deficiencies could be envisaged with any of the formulations adopted. Lower colour stability scores, though, would create commercial problems.

Colour stability and vitamin E content of fresh and processed pork

The effect of increasing muscular content of vitamin E on colour intensity and stability of pork (both fresh and processed) was studied by feeding manipulation. Fresh pork was represented by loin chops and processed pork was represented by a dry cured fermented sausage (salame Milano) and raw cured ham (Parma ham). Dietary vitamin E was increased by feeding the animals with sunflower oil and α-tocopheryl acetate at 100 and 200 ppm. Chops were packed in oxygen-permeable film and in a protective atmosphere (80% O2 and 20% CO2) whereas salame Milano and Parma ham were packed under vacuum and in a protective atmosphere (85% N2 and 15% CO2). No differences in colour intensity or type were observed in relation to vitamin E content. Colour stability tests suggested, on the other hand, that higher vitamin E contents could be associated with slower myoglobin oxidation rates in fresh chops packed in a protective atmosphere. No effect of vitamin E on colour stability was observed in salame, probably because of the soft fat induced by sunflower oil. Significant differences among dietary groups were also not observed in Parma ham.

Lean colour of green and matured Parma hams: Comparative evaluation and technological relevance of sensory and objective data

Research has been conducted on the relationship between sensory evaluation and objective measurement of pork colour. The study also investigated the relationship between the colour of fresh meat and the colour of matured hams. Sensory evaluation was carried out at 24 h post mortem on the freshly cut surfaces of green hams trimmed for Parma ham production. Objective measurements were performed at the same time on Semimembranosus and Biceps femoris muscles with a Minolta Chromameter Reflectance II CR200/08. Cold carcass weight, lean content, trimmed ham weight, 45 min and 24 h post mortem pH of Semimembranosus muscle were also recorded. The hams were processed according to Parma ham technology. Weight losses at standard processing times were collected. At the end of processing a sample of about one-third of the hams was evaluated for internal lean colour and lean firmness both by sensory panel and objective measurements. Proximate composition was also determined. The results showed highly significant relationships between colour sensory scores and the coordinates L (∗), b (∗) and hue of the C.I.E. L (∗)a (∗)b (∗) colour system. Among the other parameters measured on fresh meat only 24 h pH was related at a very significant level with sensory and objective colour values. Correlation coefficients were generally higher for Semimembranosus than Biceps femoris. Matured ham colour was linked with fresh meat sensory judgements, L (∗), hue and a (∗) values. The relationship, though, was not sufficiently strong for use in predicting the colour of matured hams from green ham characteristics. Processing appears to have a positive effect on the colour of pale meat. Weight losses were mainly linked with lean meat content; other quality attributes being less important. Lean firmness of matured hams was related to the colour and pH of the fresh meat.