POSSIBILITIES ASSESSMENT OF A COLOUR MODIFICATION IN WIENER SAUSAGES MADE WITH PLASMA PROTEINS

Krystyna Krysztofiak

ABSTRACT

In the following work, it is proved that the usage of plasma proteins has badly effected the colour desirability in wiener sausages. In order to improve the degree of pigmentation, the cured blood and solution of betanin were used. The general optimisation procedure is based on determining the connection between the amount of added pigments and the colour desirability. First it was examined what ranges of L*, a*, b* (physical colour parameters) a sensory examination colour assessment (e.g. 4.0 points) can be related to. Next, it was examined what marks for the colour desirability were given to sausages colour with different amounts of single pigments and mixtures of various proportions.

Key words: colour optimisations, sausages, plasma additives, cured blood, betanin..

INTRODUCTION

Nowadays it has become very common and popular to enrich the formulative composition of processed meat with additives. A lot of technological and economic factors have contributed to this practice. Nevertheless, taking into consideration customers’ preferences, it is necessary to make meat products with a traditional sensory characteristics despite their changed composition. For the average customers it is important that the meat product containing protein additives should meet the standard of a sensory quality of the product made without additives, which applies mainly to the colour and the taste [10, 12, 14]. After the unification Polish food law, concerning meat products, with EU standards, there will be for more possibilities of forming these product features [4, 5, 9].

Establishing a of definition of the “proper colour” of a meat product is difficult. The appropriate colour is this one which matches, traditional preferences of a consumer in respect to a particular type of product [1, 10, 12]. Every deviation a particular product from the expected colour is recognized as a bad quality signal.

Scientists have been trying to eliminate the process of meat curing for a long time. Moreover, the colour of meat products with a lot of additives or made from pale coloured exudative meat, was not satisfying. Therefore, colouring the meat products was essential and necessary [4, 5, 11, 14].

When the meat is replaced with a protein specimen, there are fewer additives in the batter which has a negative impact on the colour of the meat. The type of this change has also to do with the colour of the pigment substitute. While the white pigment substitute change the product, into white, the cream or greyish ones darken it and worsen the colour’s purity. The deeper is the pigment substitute, the more it is that there will also occur a change in the shade of the colour of the meat product [6, 14].

Together with the blood plasma, the sausage is filled with colourless aqueous solution of proteins without pigments. The possibly light pink colour of plasma indicates the occurrence of small amounts of hem pigments of similar features of the colour such as myoglobin and its derivatives. Adding plasma does not change a shade of colour itself. That is why: haemoglobin can be used for modifying the colour of experimental sausages. However, as it changes molar concentration of pigments, it may brighten the colour of a meat sample. The appropriate amount of cured blood should darken the colour of product without changing its colour tint. The other pigment which was tested for colouring sausage “parówkowa” type was the betanin also known as the red pigment of a beet. Betanin was suggested as a pigment for improving the colour of meat and sausages which contain protein substitutes [2, 3, 4, 5, 11] and has been excepted in EU as a substance for colouring some meat products without any quantitative limits. In both cases it is necessary to establish the suitable amount of the pigment with would be optimal for a potential colour improvement.

THE OBJECT OF THE STUDY

The following work considers possibilities of colour modification in wiener sausages made with a great deal of protein specimen. The object of the work is to establish the colour optimisation which means to calculate the amounts of pigments necessary to obtain a better and more favourable colour of the sausages.

RESEARCH MATERIALS AND LAYOUT OF THE STUDY

The research materials included: dried spray pork blood plasma and wiener sausages:

• check sausage without blood plasma and of the following composition: pork s.III - 50%, beef s. - 25%, fine fat - 25%, curing mixture-2% spices - 0.3% (black pepper, chilli, nutmeg), water - 40% of total mass;

• specimen sausages which were made without on the bases of ingredients of the check sausages, how ever percentage of proteins was (10, 15 or 20%) included in the specimen sausages was obtained by removal of a relevant amount of meat. The missing protein was replaced with pork blood plasma. The water and fat level in specimen sausages were a to the check sausages composition.

Sausages were made accordance with the specimen recipe. For colouring cured blood and 30% solution of betanin were used. First, the influence of blood plasma on the colour of model sausages was examined. Next the possibilities of colour modification in these sausages were tested.

RESEARCH METHODS

A 5-points’ method was used to carry out the sensory colour desirability assessment of colour of a singular sausage and the colour of its cross-section. This method was prepared according to directions included in the obliging standards [7, 8]. The measurement was carried out by a spectrometer. The light reflection degree was examined every 10 nm and the results were presented in CIE L*a*b* system.

RESULTS ANALYSIS

Plasma proteins and their influence on the colour of specimen sausages

At this stage, of research the most important criteria was of the viands assessment sensory colour evaluation of the sausage link and its profile [10, 14].

In sausages with 10% exchange of meat proteins for plasma proteins the results show the stronger impact of a series having to do with the raw materials’ changeability than the influence of plasma proteins’ exchange. In sausages with 15% and 20% exchange of meat proteins for plasma proteins these two colour characteristics got worse. In check sausages the colour of the link was evaluated at 4.4 points and the colour of the profile at 4.3 points. The same parameters in check sausages with 15 % exchange were given respectively – 4.0 points and 3.0 points. The observed differences are statistically significant and there emerges a question – what are the possibilities of reducing these differences?

Evaluation of the possibilities of colour modification in sausages

In the case of one kind of sausage, continually made from the same raw material, the colour can be modified in of trial and error. In practice, however, the mentioned problem is more sophisticated and so strict ranges of pigment additives should be defined, for in order to achieve the particular objective.

The solution to this problem can be divided into three stages:

• finding a connection between the amount of protein additives used and the change in the colour of the product;

• finding a connection between the sensory sausage evaluation and physical parameters values of its colour;

• establishing the relation between the amount of pigment additives and its influence on physical colour parameters of experimental sausages and their sensory quality.

Thus, after establishing whether or hot and how the change in raw materials’ composition exerts an impact on the colour of the product, we undertake an attempt to optimisation the colour.

To find a connection between the sensory colour assessment and the values of physical parameters of colour a lot of frankfurters of different raw material composition were made. Colour of these sausages underwent sensory and instrument evaluation. The results were mathematically analysed to find the connection between the results of the sensory and instrumental evaluation. These connections turned out to be well described in terms of polynomial of the 3^rd degree, which is shown in Figures 1, 2, 3. The determination coefficients R² were: for colour brightness (L*) 0.9392, for red (a*) 0.8852 and for yellow (b*) 0.7959. These correlations are very high which enable to obtain exact interpolations expected results. In this way ranges of colour parameters can be defined where the sensory colour evaluation is positive. In this experiment a sausage which got at least 4.0 points was tested. Additionally, the ranges of colour parameters for 3.5 points were shown in the pictures. The results are shown in Table 1. They enable correlate sensory evaluation apparatus measurements.

The next part of research consisted in establishing the influence of the amount of added pigments on the colour parameters in specimen sausages with 15% exchange of meat proteins for plasma proteins of pork blood. For colouring, as before, the cured blood and 30% aqueous solution of betanin were used.

As a result, it was proved there is a strict connection between physical parameters of colour and the amount of the added cured blood. These connections are shown in Figures 4, 5, 6.

As it was expected, adding cured blood to a great extend positively affected the red colour of the product. It is caused by a great similarity of reflexion spectra haemoglobin and myoglobin and their derivatives. Unfortunately, the side effect of adding cured blood is a significant decrease in the colour brightness of the product.

In order to univocally define the colour 3 parameters L*, a* and b* are required. Therefore the optimal amount of cured blood will constitute a common part of the ranges presented in Figures 4, 5, 6. The results are shown in Table 2.

The same tests were conducted on samples coloured with the aqueous solution of betanin. The conclusion was that the adding solution of betanin affected the colour of the examined sausages. The results of those tests are shown in Table 3.

With a slight amount of betanin the maximum number of points received for the colour evaluation is 3.3 points.

In this situation the following question remains how will the colour of sausages change after adding both these pigments – the cured blood and the solution of betanin. To find the answer, a lot of additional research was performed. From sausage batter of 15% exchange of meat for plasma proteins, a lot of sausages were produced. One was left without colouring, the rest was coloured with cured blood, the solution of betanin and with a mixture of pigments. The sensory examination of the colour desirability was performed on a sausage link. The results of those tests are shown in Table 4.

It is important to point out that the check sausage (without plasma proteins) produced at the same time, got an average mark of 4.8 points.

The usage of the dried pork blood plasma badly affected the colour desirability in sausages. The sausage made with blood plasma without any pigments, obtained the mark of 3.09 points. Colouring sausages with cured blood and the solution of betanin yielded varied results. Therefore there has emerged a necessity pigment additives to define the optimal composition of a colouring mixture.

In connection with the above, equations of multiple regression of the 2 degree were calculated where the sensory examination was the dependent variable and the pigment additives were the independent variables. For calculations a computer program was used. As a result, the equation number 1 was defined.

Equation number 1

y = 3.56 + 1.997K – 0.654B – 0.163BK –1.048K² – 0.510B²

R² = 0.886
The result standard error – 0.356

where:
Y - the expected result of the sensory examination,
K - the amount of the cured blood additives,
B - the amount of betanin.

Not all of this equation’s variables have a statistically significant impact on the final result. Therefore additional calculations were made, successively eliminating highly insignificant variables. As a result equation number 2 was defined.

Equation number 2

y = 3.74 + 1.89K - 1.42B - 1.05K²

R² = 0.833
The result standard error – 0.345

Using particular partial derivatives in equation 2, the dependent variable reaches its maximum value with B = 0% and K = 0.9% which is 4.6 points. Similar calculations can also be done as regards equation 1. In this equation K = 1.015% and B = -0.803%. The negative value of B indicates the bad effect of betanin on sausage in colour evaluation.

Obviously, for other sausages the results may be completely different, but every time the described above optimisation procedure of colour modification may be applied.

CONCLUSIONS

1. A 15% exchange of meat proteins for pork plasma proteins has badly affected to a statistically significant extent the colour of sausage link and its profile.

2. Applying the optimisation procedure presented in the paper makes it possible to establish whether the pigments used improve the colour desirability of the examined sausage of define the required amounts of colouring substances

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