EFFECT OF ENRICHING MODEL MEAT PRODUCTS WITH OILS, ABUNDANT IN POLYUNSATURATED FATTY ACIDS ON THE SELECTED QUALITY PARAMETERS

Halina Makała
Meat and Fat Research Institute, Warsaw, Poland

ABSTRACT

The application of linen oil and fish oil as added to model meat products in aspect of the improvement of fatty acid profile, characteristics of the run of oxidative changes and the selected quality indices, was examined. The studies were conducted on a model meat product, on Bologna-type sausage (mortadela) which was enriched with linen oil or fish preparation. The examination of basic composition were carried out; fatty acid composition and dynamics of oxidative changes was determined; sensory profile evaluation was conducted, as well. As a result of the performed studies it was found that enrichment of the model meat products with flax oil or fish oil caused a significant increase of PUFA : MUFA ratio. In the product with the addition of flax oil, a significant increase of the sum of fatty acids DFA, as lowering cholesterol level, was also observed. The introduction of fish oil preparations to the meat products caused the increase of the content of polyunsaturated fatty acids. Dynamics of oxidative changes, characterized by acid value, peroxide value and anizidine number and by the calculated index totox was dependent on the type of the oil and storage period. The product with the addition of fish oil was characterized by the highest desirability of flavour (smell and taste) and colour and the lowest hardness, springiness and sensation of fattiness. The control product and that one, containing flax oil were characterized by a similar sensory profile.

Key words: meat products, enrichment, linseed oil, fish oil, quality.

INTRODUCTION

Everyday diet in Poland is so poor in fatty acids, especially those ones from n-3 family, that any enrichment of food products in the mentioned group of active components is desirable [3, 4, 28]. The enrichment of food means adding of one or few nutrients to the selected products, irrespectively of their natural presence in the product or its absence; the aim is to correct or prevent their deficits in whole population or in population groups. The enrichment of food products is considered as the most effective and most profitable way of preventing the deficits of minerals and vitamins, being safer than supplementation [2].

The components, being significant from nutritional viewpoint, and occurring in fats include fatty acids with a differentiated degree of saturation. The essential unsaturated fatty acids (EUFA) are necessary for correct development of young organisms and maintenance of good health state for the whole life. Fatty acids – due to the contained EUFA – which have therapeutic properties, i.e. lower cholesterol level, prevent hearth and blood vessel diseases, affect favourably immunological and nervous systems and have anti-inflammatory effect – cannot be replaced by other food components [1, 6, 7, 9, 10, 28]. The quality of the consumed fats is, therefore, very important.

Vegetal linseed oil (Oleum lini) is a rich source of essential unsaturated fatty acids (EUFA) and in particular, polyenic fatty acids with three double bonds in hydrocarbonic chain, i.e. α-linolenic and γ-linolenic acids. They have a positive influence on human health [16, 28]. The method for rising the participation of EUFA in the diet, especially of such acids as long-chained fatty acids from n-3 family (eicosapentaenoic acid – EPA and dokozapentaenoic acid – DHA) may include enrichment of certain products with fish oil; it refers also to meat products where the participation of, first of all, saturated acids is considerable [8].

Quality improvement and fatty acid profile in meat products may be obtained by the addition of various animal fat replacers such as carbohydrates or/and vegetal oils, not causing any changes in nutritional habits [12, 13, 15, 27]. Apart from favourable correction of their nutritional value, the additive of vegetal oils to meat products may also play a role of functional additive. The obtained effects are dependent, inter alias, on a type of oil, degree of its exchange in relation to animal fat and parameters of technological process [14].

The aim of the work was to evaluate the addition of linseed oil and fish oil to model meat products in aspect of improving fatty acid profile and their influence on the selected quality parameters.

MATERIAL

The studies were conducted on model meat product of Bologna type sausage (“mortadela”). Basic recipe of the product (control) was composed of such raw materials as beef of grade II (33.3%), pork of grade III (33.3%), yowl (33.3%), salt (1.8%), seasonings and besides it, 40% of ice water.

In the evaluated variants, linseed oil (L) with a low content of linolenic acid (from n-3 family) or fish oil (R), in the quantity of 0.6% in relation to the product weight, was introduced to batter. The aim of the additive was to enrich the meat product with unsaturated fatty acids and to improve the quality of their profile.

Model product was manufactured according to the production technology of Bologna type sausage. The batter, as obtained in chopping process, was filled in the protein casings with diameter ø 60 mm up to the weight of ca. 500 g and placed in scalding – smoking chamber at temperature of 40°C for 1 hour. Then, the sausages were subjected to drying and smoking process at temperature of 50° – 70°C for 1.5 h, pasteurization in water with temperature of 75°C till obtaining temperature of 72°C in the geometric centre of the product. After cooling down with cold water and drying, the sausages were placed in a cold room. After 12 h, the model products were closed, under vacuum, in film bags and stored at cold storage room at temperature of 4-6°C till the moment of collecting the samples for tests.

METHODS

In model meat products of Bologna sausage type, the following tests were carried out:

– Chemical tests which included analysis of basic composition, i.e. determination of water content (PN ISO 1442:2000), protein (PN-75/A-04018), fat (PN ISO 1444:2000), carbohydrates (PN-85/A-82059) and chlorides (PN ISO 1841-1:2000) and based on the obtained results of determinations, caloric value was calculated.

– Sensory profile evaluation was conducted in accordance with the principles of standards PN ISO 11035:1994 and PN ISO 41219:1998, and the following discriminants were characterized in the scale from 0 to 10 scores: hardness, springiness, chewiness, fatness feeling, and desirability of colour, smell, taste, consistence and general desirability of the product. Sensory quality and profile evaluation was carried out by 8-10 person team of qualified judges at Sensory Laboratory of the Meat and Fats Research Institute which satisfied generally the aspects of designing in sensory analysis laboratory, as required by standard PN ISO 8589:1998, using the computerized system of collecting and analysing the data ANALSENS.

– Determination of fatty acid composition was performed by a gas chromatography, on methyl esters (prepared acc. to PN-ISO 5509), using instrument of Hewlett-Packard HP 6890 equipped in flame-ionization detector, high-polar column with BPX 70 phase, length of 60 m, film thickness of 0.25 µm and internal diameter of 0.25 mm, at the programmed time and temperature. The results of analysis were automatically calculated according to the principle of internal standardization, using program ChemStation version A 03.34^® 1989-1994.

– Determining acid value (PN-EN ISO 660) and oxidative changes were characterized peroxide (PN-EN ISO 3960) value and anizidine (PN-EN ISO 6885) value and calculation of fat oxidation index – Totox. The change of level above the mentioned figures and of the calculated coefficient was examined during cold storage (4-6°C) without an access to light during 0, and after 2, 4, 6 and 8 weeks since manufacture.

Each experiment was carried out in two repetitions. The obtained results of the tests were subjected to statistical analysis using Statgraphics programme.

RESULTS AND DISCUSSION

Tests of basic chemical composition, sensory profile and of the fatty acid composition and profile

Characteristics of discriminants of basic chemical composition of model products, the control product and that one with the addition of linseed oil or fish oil is given in Table 1. As a result of the conducted single-factor variance analysis, a significant differentiation of the studied parameters was found; it may be justified by biological variability of raw materials used in production rather than as a result of the additive of the examined oils.

Sensory profile of the evaluated products is given in Figure 1. The control product and that one with linseed oil were characterised by a similar sensory profile. The product which contained fish oil showed the lowest hardness, springiness and fatness feeling and was characterised – as compared to the remaining variants – by the highest desirability of such discriminants as colour, smell, taste and general desirability. Weakening of hardness, springiness and fatness feeling did not have any effect on the evaluation of the discussed product on the same level of consistency desirability as the remaining variants.

Fatty acid profile of the raw material – linseed oil with a low content of linolenic acid and fish oil and of model products enriched with their additive is given in Table 2. The examined oils, marked as (L) and (R) differed in composition and mean fatty acid level. Linseed oil (L) contained 91.2% and fish oil (R) had 75.4% of unsaturated fatty acids. The examined oils differed also in the content of mono- and polyunsaturated fatty acids, especially in PUFA/MUFA and PUFA n-6/PUFA n-3.

Enrichment of the model product with the linseed oil or fish oil caused small increase of the sum of polyunsaturated fatty acids in Bologna type sausage (mortadela), from 10% in the control product K to 10.7% in variant PL and 11.0% in variant PR. Enrichment of model product in fish oil caused that proportions of the sum of polyunsaturated fatty acids and monounsaturated fatty acids (PUFA: MUFA) were the highest, i.e. 0.22 (0.19 in the control product) and the PUFA n-6/PUFA n-6 ratio was the lowest from among the examined variants. On the other hand, in the product, enriched with linseed oil, we could state the significant increase of the sum of cholesterol-reducing fatty acids and PUFA n-6/PUFA n-3 ratio, as compared to the control products. Similar observation were also found by Kühne [11] who demonstrated that the addition of linseeds in the quality of 10 and 4 g/kg. Respectively, in pig feeding caused a decrease of fatty acids from n-6 and n-3 family from 8.1 to 2.5. In order to maintain the appropriate imminity and development of human organism, mutual proportions of the sum of fatty acids of n-3 type and fatty acids of n-6 familly should be of order 6:1 to10:1 [5] and according to FAO/WHO data, the proportions of the recommended daily consumption of polyunsaturated fatty acids by man should be found within 5:1 to 10:1.

Storage tests

Character of determining acid value and oxidative changes in control product and products, enriched with the linseed oil or fish oil during cold room storage was dependent on the type of the introduced oil (Table 3). Enrichment of the product with linseed oil (L) with a low linolenic acid content caused that acid value was lowering, during the storage period, from the highest initial value (among the evaluated variants) of 1.53 mg KOH/1 g and that trend had a linear character. The changes in acid value of the product with the addition of fish oil revealed also decreasing tendency during the storage. It is probable that a low level of the addition of the both oils as well as of the natural antioxidant (rosemary) slowed down a dynamics of oxidative changes significantly, especially during the period after 4 weeks of cold storage.

During the period from manufacture till 4 weeks of cold storage, significant decrease of acid number value was also observed in the con troll sample as well as in variants with the addition of linseed oil or fish oil; after the mentioned period, the repeated increase was recorded. Similarly as in case of acid number, a similar effect of the type of oil on dynamics and character of changes in peroxide value was observed.

Similar tendencies were observed for anizidine number and calculated coefficient of fat oxidation – Totox. During the period from “O” till 4 weeks of cold storage, the recommended shelf life period for this assortment of meat products, a linear decline of anizidine number as well as Totox coefficient was recorded. After this time, value of the discussed parameters of oxidative changes is increased again. Probably, the additive of natural antioxidant “protects” the product for the recommended shelf life period; after this time, their value increases again as a result of generation of oxidative change products.

Directions and rate of oxidative changes in model products, enriched with the linseed oil or fish oil were dependent on the type of the employed oil and fatty acid profile. During the storage tests, the observed oxidative changes in the product, containing linseed oil or fish oil, were significantly different as compared to the control product.

CONCLUSIONS

As a result of the conducted studies, it was found that enrichment of the model meat products with linseed oil or fish oil caused a significant increase of PUFA/MUFA ratio. In the product with the linseed oil additive, a significant increase of the sum of fatty acids DFA, lowering cholesterol level, was observed. Introduction of fish oil-containing preparations to the meat products caused the rise of polyunsaturated fatty acids.

The product with the additive of fish oil was characterized by the highest desirability of smell, taste and colour and the lowest hardness, springiness and fatness feeling. The control product and that one containing linseed oil were characterized by a similar sensory profile.

Determining acid value and dynamics of oxidative changes, as being characterized by peroxide and anizidine value, and with the calculated Totox index was dependent on the type of the employed oil and storage period.

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Accepted for print: 26.04.2007

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