EFFECT OF κ–CARRAGEENAN ON COLOUR STABILITY OF MODEL PRODUCTS WITH DIFFERENT LEVELS OF FAT

Zbigniew J. Dolatowski, Magdalena Olszak
Department of Meat Technology and Food Quality, Agricultural University of Lublin, Poland

ABSTRACT

Obtained results pointed out that the addition of κ-carrageenan in meat products do affects the examined parameters of colour during cooling storage. Model products produced from the cured beef and mince pork fat salted. To share samples 0.5% κ-carrageenan was added (test samples). The study was realized after 1, 10 and 20 a days of chilling storage. Oxidation-reduction potential, pH, TBA and colour of products were tested. The pH of the patties measured using a pH meter (CPC-501) with electrode ERH-111. Oxidation-reduction potential was determined using a pH meter (CPC-501) set to the milivolt scale and equipped with a redox electrode ERPt-13. TBA number was calculated as mg MDA/kg samples. The measurement of colour was conducted by using an X–Rite Colour Premier 8400 reflection spectro-colorimeter. Colour parameters of products were determined in CIE L*a*b* system, using illuminant D65 and 10° observer angle. The supplement of κ-carrageenan didn’t have an influence on acidity of meat products, however differentiated content of fat influenced pH value. No significant effects of κ-carrageenan on redox potential values were observed. Oxidation-reduction potential values of meat samples increased during the storage. The color analysis revealed that products with no к-carrageen addition were characterized by the highest redness; the compound affected the increase of yellow color share and did not influence on product’s brightness.

Key words: meat products, κ–carrageenan, oxidation-reduction potential, TBA, colour.

INTRODUCTION

Characteristic red color of muscle tissue is mainly associated with the myoglobin presence that makes up to 90% of the total content of haem pigments in meat. A form, myoglobin occurs, varies: in its basic form – it is red or dark red, in moderately oxidized form (oxymyoglobin) – it is light red, and in oxidized form (metmyoglobin) – it is brown-red. The haem pigments in meat are the compounds that can be easily changed due to various physicochemical factors such as temperature, acidity, water absorption, light access, redox enzyme action; in particular, they can be easily oxidized, which is a consequence of their unsaturated character [2, 3, 7, 8]. Processes occurring in fats (lipid oxidation) are additional factor that changes color, aroma, taste and nutritional value of a product. Products of lipid oxidation and free radicals contribute to oxidation of myoglobin leading to formation of metmyoglobin (browning) [9, 15]. The intensity of red color also depends on meat composition and its structure. Fat with connective tissue dispersed around muscle bundles optically lighten the red color. During the technological processes, myoglobin is bonded to carbon oxide (smoking) or nitrogen oxide (curing) resulting in two other complexes formation: carboxymyoglobin and nitrosomyoglobin, which make the meat products red color [2, 3, 7, 8]. Post-production color changes are more apparent when the share of pigments in raw meat is higher. Color of a meat product is the most desirable directly after technological process completing, because no processing stage completely inhibits the decomposition of chemoproteids, only making its course slower. Prolongation of meat products color durability can be achieved by natural compounds, radicals groups present in raw meat and chemicals added during the technological process [6]. Ascorbic acid, commonly applied in production, is an additive that decreases the antioxidation activity. However, vitamin C becomes highly susceptible to oxidation in a presence of metal ions such as Cu(II) and Fe(III). Thus, the presence of synergents (e.g. carnosol, in this case) is very important [9].

The main objective of this study was to evaluate the influence of κ-carrageenan on the colour of cured meat product with differentiated level of fat content during chilling storage.

MATERIALS AND METHODS

Meat products preparation
The study material consisted of fine-ground (homogenous) meat products with addition of к-carrageen at amount of 0.5%. Cured beef (musculus semimembranosus) with 2% addition of curing mixture (99.5% NaCl and 0.5% NaNO₂) and salted fine fat (2% NaCl) was used for production. Following variants of model products (Table 1) at constant ice water content (30%) were prepared: A – 50% meat, 20% fine fat; B – 40% meat, 30% fine fat; C – 30% meat, 40% fine fat (control). Aliquots of 0.5% κ–carrageen instead of muscle tissue (control sample) were added into each combination.

The material was preliminarily ground in laboratory mill with 3 mm mesh, then homogenized in laboratory cutter (Robot-Cupe, model R3 V.V.) for 4 min at 2500 rpm. Temperature of fillings did not exceed 12°C during cutting. Fillings were packed into glass pots and pasteurized at 75°C till achievement 70°C inside the material. After cooling, samples were stored at 4°C. Following items were determined after 1, 10, and 20 days of storage under cooling conditions.

Meat products acidity
pH was measured by the using digital pH/conductometer (CPC501) and combined electrode (type ERH-111) in water extract of the product (homogenate: 10 g of product plus 50 ml of distilled water).

Oxidation-reduction potential (ORP)
Oxidation-reduction potential was measured by the using combined electrode (type ERPt–13) plugged into digital pH/conductometer in water extract with BHT addition in accordance to the method by Nam and Ahn [10]. Achieved result was recalculated onto redox potential value in relation to standard hydrogen electrode E_H (in mV). Thus, known value of reference electrode potential (E_odn = 211 mV at 20°C) was added to measured potential.

Thiobarbituric acid (TBA) Malonic aldehyde concentration (MDA)
Lipid oxidation was measured as 2-thiobarbituric acid. TBA values of samples were determined according to the modified method of Salih according to Pikul [12]. TBA values i.e. concentration malonic aldehyde was expressed in milligrams per kilogram of the product.

Color evaluation
Color was determined by reflection method using spherical spectrometer (X–Rite Color) with measurement whole of 25.4 mm diameter in CIE L*a*b* system. Using illuminant D₆₅ light source and standard colorimetric observer with 10° vision field was applied. Following parameters were determined: L* – color lightness, a* – chromaticity within red-green spectrum range, b* – chromaticity within yellow-blue spectrum range. The instrument was standardized using standard white plate (L* = 95.82, a* = -0.44 and b* = 2.50). Samples for color determination were cut in a form of rectangle (30×40×10 mm) and exposed to dispersed daylight. Measurements of color were made every 0.5 h for 2 h of exposure.

Statistical analysis
The experiment was conducted for 3 product series in 3 replications each. T-Tukey’s test (α = 0.05) was applied to verify the difference significance.

RESULTS AND DISCUSSION

Results (Table 2) revealed significant influence of fat level on product’s acidity. Samples containing 40% fat were characterized by the highest and those with 20% fat – the lowest acidity. At the first storage day, the acidity for 20% fat share was 5.82 for variant A (lowest) and 5.95 for variant C (highest). Similar situation was observed at the 10^th day, but acidity decreased and the greatest drop was recorded for products containing 40% of fat. Assessment made at the last day of storage indicated that acidity was similar for all samples (5.80-5.86, respectively for A and C). Study revealed that к-carrageen did not affect the acidity of tested samples directly after producing and during storage period. However, it depended on fat content (Table 2): pH value decreased during the storage.

Measurements of oxidation-reduction potential changes (Table 2) revealed that its increase was observed for the whole storage period: samples C and C’ were characterized by the highest (308 mV), and samples A and A’ the lowest (305 mV) values at the first day. At the 10th day of storage, the oxidation-reduction potential increase (by 10 mV, on average) occurred for samples with 30% and 40% of fat; the increase was slight for samples containing 20% of fat and their oxidation-reduction potential was at the level of 308 mV. Further storage caused stronger potential increase for all samples. It was the highest for C and C’ (331.8 and 341.6 mV, respectively). As similar as in the case of acidity, no influence of к-carrageenan addition on oxidation-reduction potential course was observed. Instead, it depended on fat content in particular samples. In redox reactions, a system that has higher oxidation-reduction potential is in general the oxidant [5], which was confirmed by present TBA results. As Rödel [13] stated, redox potential is subjected to continuous variations during meat products storage and it changes along with the pH value. When pH increases from 5.8 to 6.2, oxidation-reduction potential decreases by 40 mV. Achieved results confirmed Rödel’s [13] observations.

It was found that к-carrageenan addition did not affect the amount of malonic aldehyde. Its slightly higher content was observed in control samples. At the first day, TBA value was at the level of 0.61-0.7 mg·kg^–1 of product (for C and A samples, respectively). The increase of malonic aldehyde content was recorded at the 10th day of storage: 0.78mg·kg^–1 of product for samples with κ-carrageenan, and 0.86mg·kg^–1 of product for control. Further storage caused the TBA level exceeded 1 mg·kg^–1 of product with maximum for B’ sample (1.26 mg·kg^–1 of product). Higher values of TBA in samples with no carrageenan addition were also observed by Candogan and Kolsarici [2].

Achieved results for color parameter L* during cooling storage showed the lowest share of color lightness for products containing 20% of fat, and the highest for samples with к-carrageenan addition at 40% fat content. Products with great amounts of beef are more red due to haem pigments content, and fat makes the color shade is shifted towards white [8, 11, 14].

Color lightness (Fig. 1) at the first day for products A and A’ was the lowest (65.90 and 65.64, respectively) and the highest for C and C’(71.82 and 70.57, respectively). At the 10th day of storage, the increase of color lightness by 2 units occurred for product A; it was constant for the whole storage period in the case of other samples. The color lightness for products A and A’ as well as B and B’ was at similar level at the last storage day (66.08, 66.19, 69.06, and 68.35, respectively), meanwhile it slightly differed for C (71.25) and C’ (69.44). Achieved results indicate that products with κ-carrageen addition were characterized by lighter color parameters. Between fat level and meat products colour appear relationship was obserwed in other studies [6, 8, 11, 14].

Values of parameter a* (Fig. 2) for particular samples quite dynamically varied. The increase of red color share was observed in control samples A’ and B’ during 20-day storage; sample C’ revealed slight decrease of the parameter was recorded. Similar situation was for samples with κ-carrageen addition, but the values were much lower. It can be accounted for the fact that the presence of additives influences on color depth. In the case of additives due to which more water or fat can be introduced, haem pigments become “diluted” [8]. Redness of samples also depended on fat content: the more fat, the less share of red color. Other scientists found similar traits [1, 2, 6, 7, 14]. At the first day of storage, sample A’ was characterized by the highest redness (4.74), sample C the lowest (3.07). Similar observations were made after further storage (20 days): A’ – 5.25 and C – 2.84.

Contribution of yellow color in tested products remained at constant level during the storage: products with 20% fat content were distinguished by the lowest values (Fig. 3).

Analysis of parameter b* value at the first day revealed that it was similar in samples A, A’, B and C (14.89–15.43), or higher for B’ and C’ (16.33 and 15.76, respectively). At the 10th day, the lowest yellow share was found in products A (13.90) and A’ (14.80), and the highest in C and C’ (16.0). The decrease of yellow color share was recorded at the 20th day for samples with 20% (up to 13.14), and 40% fat content (to 16.0) as well as for sample B (up to 15.14); sample B’ showed the increase of the parameter (up to 16.88).

Evaluation of color durability during irradiation (Fig. 4) indicated that after 2 h of daylight exposure, the greatest differences of color parameters were observed for samples with 20% of fat content, in which dyes level was the highest. Myoglobin is unstable compound: it is converted into oxidized brown metmyoglobin when oxygen concentration grows. Acidity is another factor that affects the color: its decrease causes color brightening [3, 6,7], which was confirmed by achieved study results.

Analyses made after the first day of storage (Fig. 4) during meat products exposure to daylight revealed that color brightness decreased except from samples A and A’ with subsequent increase by 3 units at the end of exposure to daylight (after 1.5 h) in sample A from 65.6 to 68.6 and decreased again to a level of 64.4 for sample A and 62.7 for A’. At the same time, these samples were the darkest; sample C was the lightest (68.60). Observations of color changes due to exposure to daylight revealed that color lightness decreased along with the storage. For sample A, whose lightness was the lowest after 10 days, exposure to daylight caused that the parameter was 64.92 and after 20 days – 64.12. In the case of sample C with the highest lightness at the last hour of exposure, the parameter was 67.48 after 10 and 66.50 after 20 days of storage. Results of study upon parameter a* value indicate that samples after the first and 20th day of storage were characterized by the highest stability. Sample A’ was characterized by the highest redness during exposure and during the whole storage period after 2 h of exposure reaching 4.5. Samples C and C’ were distinguished by the lowest redness: the value was about 3.0 after 20 days of storage. Analysis of parameter b* value during the period of meat products exposure to daylight indicated that yellow color share increased along with time for all samples tested. Value of parameter b* was at similar level for particular samples during the whole storage period at the end of daylight exposure. Sample C was characterized by the highest yellowness after 20 days of storage and daylight exposure (18.07), sample A’ – the lowest (15.68). Similar tendencies in shaping the color parameters during daylight exposure were observed by Kłosowska et al. [7] and Cierach et al. [3]. They found that product’s color worsened with the prolongation of daylight exposure time. The greatest color changes occurred at the first hour of exposure to daylight with subsequent decrease along with the exposure time.

CONCLUSIONS

Studies upon the к-carrageenan addition influence on selected physicochemical properties of the products with varied fat content revealed that product’s acidity did not change due to the additive, but fat level. It can be supposed that triacylglycerides hydrolysis occurs. The acidity changes might have affected the rate of releasing the peroxide anionic radical by hemoglobin, because its amount increases at low pH and at the presence of some anions, e.g. chlorides [5].

That phenomenon could have the influence on redox potential and malonic aldehyde presence in tested samples. Values of redox potential parameters did not show being affected by к-carrageenan addition. Decrease of its level in samples with к-carrageenan was found during the malonic aldehyde determination.

The color analysis revealed that products with no к-carrageenan addition were characterized by the highest redness; the compound affected the increase of yellow color share and did not influence on product’s lightness.

Tests of color stability due to time of daylight exposure indicated no differences in shaping the red color parameter for products with к-carrageenan addition, but it was significantly affected by meat tissue share. Increase of meat raw material share caused the increase of haem pigments levels, which in turn influenced on their transformations during light exposure. It probably resulted from the formation of peroxide anionic radical and hydrogen peroxide, during which nitrite presence might have been the electron donor [5], which manifests as a greater decrease of product’s red color share during storage. Addition of κ-carrageenan caused the increase of lightness and yellow color share during daylight exposure.

REFERENCES

1. Adamczak L., Szczeblewska A., 2004. Wpływ temperatury poczatkowej obróbki termicznej i metody studzenia na jakosc srednio rozdrobnionych produktów blokowych [The influence of starting temperature of cooking and methods of cooling of chopped meat products]. Acta Sci. Pol. Technol. Aliment. 3, 27-36 [in Polish].

2. Candogan K., Kolsarici N., 2003. Storage stability of low-fat beef frankfurters formulated with carrageenan or carrageenan with pectins. Meat Sci. 64, 207-214.

3. Cierach M., Szaciło K., Szaciło J., 2001. Stabilnosc barwy przetworów mięsnych z dodatkiem karagenu w czasie przechowywania [Colour stability in meat products with addition of the carrageen during storage]. Inż. Roln. 10, 73-77 [in Polish].

4. Dasiewicz K., Pisula A., Strzelec M., 2004. Czynniki wpływajace na zmiany barwy wołowego mięsa mielonego [The agents influenced the changes of color of mince beef]. Mięso Wędl. 6, 40-44 [in Polish].

5. Halliwel B., Gutteridge J.M.C., 1999. Free radicals in biology and medicine. Oxford University Press, Oxford.

6. Hughes E., Cofrades S., Troy D.J., 1997. Effects of fat level, oat fibre and carrageenan on frankfurters formulated with 5, 12 and 30% fat. Meat Sci. 45, 273-281.

7. Kłossowska B.M., Tyszkiewicz S., 2000. Wybrane czynniki determinujace barwę mięsa szynek surowo dojrzewajacych produkowanych na małš skalę [The selected factors, determining colour of meat of raw-ripening hams manufactured on a small scale]. Rocz. Inst. Przem. Mięsn. Tłuszcz. 37, 127-135 [in Polish].

8. Krysztofiak K., 2001. Substancje dodatkowe w przetwórstwie mięsa [The ingredients used in meat processing industry]. W. Uchman (ed.) Wyd. AR, Poznań.

9. Lee B.J., Hendricks D.G., Cornforth D.P., 1999. A comparison of carnosine and ascorbic acid on color and lipid stability in a ground beef pattie model system. Meat Sci. 51, 245-253.

10. Nam K.C., Ahn D.U., 2003. Effects of ascorbic acid and antioxidants on the color of irradiated ground beef. J. Food Sci. 68, 689-690.

11. Pietrasik Z., Duda Z., 2000. Effect of fat content and soy protein/carrageenan mix on the quality.

12. Pikul J., Leszczyński E., Kummorow F.A., 1989. Evaluation of three modified TBA methods for measuring lipid oxidation in chicken meat. J. Agric. Food Chem.37, 1309-1313.

13. Rödel W., Scheuer R., 1998. Das Redoxpotential bei Fleisch und Fleischerzeugnissen [Redox potential of meat and meat products]. Fleischwirtschaft 78, 974-981 [in German].

14. Serdarolu M., Özsümer M.S., 2003. Effect of soy protein, whey powder and wheat gluten on quality characteristics of cooked beef sausages formulated with 5, 10 and 20 % fat. EJPAU, Food Sci. Technol. 6 www.ejpau.media.pl

15. Ulu H., 2004. Evaluation of three 2-thiobarbituric acid methods for the measurement of lipid oxidation in various meats and meat products. Meat Sci. 67, 683-687.

Accepted for print: 25.01.2007

Responses to this article, comments are invited and should be submitted within three months of the publication of the article. If accepted for publication, they will be published in the chapter headed 'Discussions' and hyperlinked to the article.