Zanardi E., Novelli E.*, Dorigoni V., Ghiretti G.P., Barbuti S., Chizzolini R.
Istituto di Scienza e Tecnologia degli Alimenti, Facoltà di Medicina Veterinaria, Università degli Studi di Parma, via del Taglio 8, 43100 Parma, Italy.
* Istituto di Patologia e Igiene Veterinaria, Facoltà di Medicina Veterinaria, Università degli Studi di Padova, Agripolis, 35020 Legnaro, Padova, Italy .
The research has been financed by the European
Commission (Contract AIR-CT93-1691).
Thanks are due to Mrs E. Campesato and Mr C.Damaschi for their technical support.
International medical institutions have been recommending for the last 40 years that dietary fat intake should be controlled both as quantity of calories and as type of fatty acids introduced. Nutritional guidelines suggest that dietary fat should provide between 15 and 30% of total calories and that saturated fats should be limited between 0 and 10% of caloric intake (WHO, 1990). Limitation in fat intake is thought to be important for preventing obesity which is considered to predispose to various chronic diseases of the circulatory system. Relationships appear to exist, also, between a high-fat intake and an increased risk of some cancers, especially cancers of the colon, breast and prostate (Flatt, 1993; Reddy, 1995).
Meat and meat products have been accused of being unhealthy for their high content of fat and of saturated fatty acids. There is a growing demand, therefore, for low-fat meat products. However, the development of low-fat products requires modifications to the products which can affect important quality attributes and, therefore, consumer acceptability of such products (Colmenero, 1995).
Raw fermented meat products, such as those known as salame, have fat contents variable from 25 to 35% and fat reduction requires specific adjustments not only of the ingredients but also of processing technology. Moreover, bacterial growth has to be verified since fermentation, which means not only microbial growth but also selection of some specific strains to the expense of others, plays an important role for the appearance of typical organoleptic quality attributes and has, also, strong links with the safety of the final product.
Fat can be reduced by using leaner raw materials and/or by substituting it with substances with a low caloric content. Possible fat substitutes can be proteins (from vegetable and animal sources) and carbohydrates of various nature (starches, dextrins, alginates) used alone and in various combinations.
The research which has been carried out was centred on a typical Italian raw fermented meat product, such as salame Milano, which can be considered representative of most raw fermented meat products. The fat content of salame Milano is normally around 30% and the research aimed at evaluating the possibility of lowering the fat content by using both lean raw materials and fat substitutes maintaining at the same time acceptable quality attributes. The study included a complete microbiological control of the most important bacteria which could be found in traditional salame and the measurement of peroxide number, TBARs and cholesterol oxidation products, due to the importance presently attributed to lipid oxidation for quality and human health reasons.
Salame Milano was produced as described by Novelli et al. (1998). The trials went through a series of different formulations to end up with three basic levels of fat content: a so called standard level varying from 25 to 30% fat, an intermedium one with about 15% fat and a low one with a fat content around 6-7%. The aim was obtained by gradually reducing the amount of fat cuts: the traditional formulation, based mainly on shoulders as lean cut, was modified increasing the amount of ham trimmings. The latter, compared with shoulders, are characterised by very lean muscles as for intramuscular fat, while most of intermuscular fat can be eliminated.
Other trials were carried out to set up formulations in which fat was substituted by dextrins (Cerestar, 01915 D.E. 18±2), sodium alginate (Sanofi, GFC 640), starch (Tipiak, Tapiocaline CR 521), and soya proteins (Protein Technology International 545).
Processing technology was modified to slow down dehydration during the first processing phases, i.e. fermentation and drying. Starter cultures (Pediococcus and Micrococcus, employed at the dose of 5 x 106 cfu/g of mince) were used as a warranty against unwelcome fermentations. In all cases the formulation of additives remained constant.
Salami were subjected to the following chemical analyses: proximate composition and NaCl content (A.O.A.C., 1990), non protein nitrogen (NNP) (Bellatti et al., 1983), pH by homogenization in distilled water in a ratio 1/10 sample/water. Lipid stability was evaluated by measuring peroxide value, TBARs and cholesterol oxides (Novelli et al. 1998).
Microbiological controls were also carried out on fresh minces and matured salami of all the formulations tested and official methods were employed for the determination and estimation of total aerobic count, Enterobacteriacee, Pseudomonas spp., Micrococcus, Staphylococcus, Lactic acid bateria, Enterococcus, Total coliforms, Fecal coliforms, E. coli, Bacillus spp., Sulphite reducing clostridia, Yeasts, Moulds, Staphylococcus aureus, Bacillus cereus, Salmonella, Listeria, Yersinia.
A check has also been performed for the presence of substances inhibiting the growth of bacteria.
Matured salami were subjected to a complete sensory evaluation by a trained panel of 10 members according to a form specifically set up (Table 1)
The most successful formulations, on the basis of sensory quality attributes, are presented in Table 2. Chemical composition data (Table 3) show the reduction in fat content and derived changes in protein, moisture and salt percentages. Using ham trimmings at increasing levels and thoroughly cleaned from visible fat, and leaving out the belly, allowed the production of salami with a fat content as low as 6.41 in formulation 3. Quality attributes, though, were not completely satisfactory as firmness came out to be excessive and a tendency was observed towards higher encrustation scores (Table 7).
The use of dextrins at high level (8%) and skimmed milk (2%) (formulation 4) gave useful indications for the control of water loss (firmness and encrustation) but responsible of a slight sweet taste. Other formulations were therefore tried in which dextrins were reduced down to 1% and mixed with other ingredients (starch, sodium alginate, skimmed milk). Starch, tried in various formulations, had to be kept at low levels for sensory reasons (see below). The association of starch (pregelatinised with hot water in the ratio of 1:4) with dextrins, and with 10% belly (formulation 5), gave acceptable results but with a fat content of nearly 20%. Slightly more successful appeared to be the association of dextrins with Na alginate (formulation 6) which, by the way, had the advantage of not requiring the use of belly and, therefore, made possible to reach a fat content of 16.4%.
Fat contents lower than 10% were obtained with formulations 7, 8 and 9 using very lean ham trimmings. The first one included dextrins with a high dose of skimmed milk (4%) and 20% shoulders; the second and the third ones were based simply on 96% ham trimmings plus 4% skimmed milk or 4% soya proteins.
Microbiological analyses did not show any differences between the various formulations neither in the minces nor in the matured products (Table 4) (only the data of matured products are shown). The use of starter cultures has certainly helped in obtaining such a result. The results are in line with similar analyses carried out by Ghiretti et al. (1997) and are characteristic of salame Milano microflora. Total aerobic count was around 107 and 108, Entherobacteria were nearly absent, the main family was represented by Lactic acid bacteria while Micrococcus+Staphylococcus and Enterococcus varied from minimum values of 104 and maximum values of 106.
Lipid oxidation studies did not show significant changes in the oxidative stability of the low fat formulations compared with the normal ones (Ghiretti et al., 1997, Novelli et al., 1998). Peroxide values (Table 5) appeared rather variable but most of them were lower than 5 meq O2/kg fat, two formulations had values around 7 meq O2/kg fat and only one formulation (n° 8) had a high value, i.e. 13.27, the highest observed. TBARS values have been found to be always very low since no formulation gave values higher than 0.3 meq O2/kg fat (Table 5). Cholesterol oxidation was always very limited (Table 6). The oxide 7keto-cholesterol was found in all samples, 25OH-cholesterol was never observed, 20a OH-cholesterol only once, 5,6a -epoxide and 7b OH-cholesterol in about half the samples. Total cholesterol oxidation was always lower than 0.1%.
Sensory evaluation was the most important parameter for the assessment of the acceptability of low fat formulations. Panel test scores are presented in Table 6.
Salame Milano with about 28% fat content scored similar values to the ones obtained in a previous experiment dealing with formulations based on different antioxidant substances (Ghiretti et al., 1997). Decreasing the fat content, to 14.75 and further to 6.41%, had negative effects on quality attributes such as firmness, which became too high in spite of reduced maturing times, and encrustation, which became more marked. The latter one is due to a higher speed of dehydration of the outer layers compared with the inner ones. The consequence is the hardening of an external ring of about 0.5-1cm which slows down the process of water loss of the inner part. The phenomenon has negative repercussions on colour which is obviously darker on the external ring and, at the same time, remains paler in the centre of the salame.
The use of dextrins as fat replacers has been useful to slow down water loss thus maintaining the right level of firmness and reducing the problem of encrusting. Dextrins at high level (8% in formulation 4) kept firmness at a low level but were responsible of a slight sweet taste. In formulations 5, 6 and 7 dextrins were associated, respectively with starch, Na alginate and a high dose of skimmed milk (4%) with positive results.
Starch, tried in various formulations, had to be kept at low levels (1% in formulation 5) since, during maturation, showed the tendency to lose water at a higher rate than muscle proteins with the result of a higher firmness and a sort of "cardboard" taste. The association with 1% dextrins and 10% belly, reported in formulation 5, came out to be the most satisfactory although with a high fat content.
Slightly better appeared to be the association of dextrins with 0.5% Na alginate (formulation 6) which also had the advantage of not requiring the use of belly and, therefore, made possible to reach a fat content of 16.4%. Encrustation was at the lowest value observed while firmness and colour parameters were placed at acceptable levels.
In formulation 7 dextrins were associated with skimmed milk and matured salame was rated approximately between formulation 2 and 6. Formulation 8, based only on lean ham trimmings and skimmed milk was acceptable for most sensory parameters but had a very intense red colour. Both formulations showed the tendency towards higher encrustation levels. Formulation 9 (4% soya proteins) came out to be similar to formulation 7 for many parameters, and in particular for firmness and encrustation values. Formulations 7, 8 and 9 had the lowest greasiness scores together with formulation 3 which was unacceptable for firmness and encrustation.
It is interesting to note, though, that all formulations with a fat content lower than 20% had greasiness scores between 1.13 (formulation 7) and 1.58 (formulation 4) with no significant differences among the low fat formulations. Colour, instead, appeared to become more intense with decreasing fat content, as could be expected. It is also interesting that formulations from 5 to 9 had scores for aged taste higher than 2.5 and higher than the other 4 formulations.
PAROLE CHIAVE: salame Milano, grasso, riduzione, tecnologia
KEY WORDS: salame Milano, low-fat, fat substitutes, technology.
SUMMARY. An investigation has been carried out to evaluate the possibility to produce salame Milano with a low fat content preserving satisfactory quality attributes. The trials have shown that acceptable low fat formulations can be produced. The simple reduction of fat content, without the use of substitutes, has been possible down to about 15% total fat content; a further reduction below 10% gave problems mainly with encrustation, firmness and colour. Some fat substitutes, namely dextrins, sodium alginate, milk and soya proteins, in various combinations, have been found useful and acceptable products have been obtained with a fat content between 8 and 9%.
RIASSUNTO. La ricerca di cui si presentano i risultati ha avuto come scopo di valutare la possibilità di produrre salami Milano a ridotto contenuto di grasso con attributi qualitativi accettabili. Lo studio ha dimostrato che la riduzione del contenuto di grasso, senza l’impiego di composti di sostituzione, è possibile fino a circa il 15% mentre ulteriori riduzioni rendono più difficile la gestione tecnologica della stagionatura cui segue comparsa di problemi di incrostazione, consistenza e colore. L’impiego di alcuni sostituti del grasso, nel caso specifico le destrine, il sodio alginato, le proteine del latte e della soia, combinati in vario grado, ha consentito di ottenere prodotti stagionati con contenuto di grasso anche dell’8-9% e con caratteristiche organolettiche accettabili.
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