THE EFFECT OF SELECTED ADDITIVES ON REDOX CHANGES IN VACUUM STORED SLASKA TYPE SAUSAGE

Agnieszka Bilska, Krystyna Krysztofiak, Jacek Grzesiak, Wojciech Timm, Waldemar Uchman
Institute of Meat Technology, University of Life Sciences in Poznań, Poland

ABSTRACT

The effect of an addition of citric acid, isoascorbic acid, sodium ascorbate and tocopherol on redox changes was analyzed in the lipid fraction of vacuum stored Slaska type sausage. It was observed that the kind of additive and storage time of the product had a statistically significant effect on all analyzed indexes. The lowest value of the redox potential was found for the sample with the highest addition of isoascorbic acid, but the lowest amounts of sodium ascorbate and citric acid. Moreover, statistically significant correlations were recorded between nitrite residue and pH–value and between nitrite residue and redox potential.

Key words: antioxidants, additives, redox, potential, vacuum packaging, sausage, storage.

INTRODUCTION

The most important tasks of meat industry include the development of products exhibiting high consumer quality and relatively long shelf life.

Vacuum packaging consists in the evacuation of air from the packaging, which is next tightly closed, usually heat-sealed [3,4]. This facilitates protection against the development of microorganisms and extension of shelf life, as well as reduces drying and loss of flavour. Vacuum packaging has been also proved an effective method to reduce oxidation in meat and meat products [4].

Oxidative processes in meat and meat products may also be effectively monitored and controlled using antioxidants. They are not only classical reducing substances such as BHT or vitamins A, C and E, but also substances, which as a result of specific action either inhibit or prevent reactions with oxygen. These include short chain acids and their salts, as well as polyphosphates, which bind metal ions Fe^2+/3+, Cu^1+/2+, Pb^2+/4+ [2,13,15].

The aim of the study was to investigate the effect of selected additives, i.e. citric acid, isoascorbic acid, sodium ascorbate and tocopherol on redox changes of the lipid fraction of vacuum stored Śląska type sausage.

It can be found by checking of changes in the peroxide value, redox potential and nitrite residue.

MATERIAL AND METHODS

Experimental material consisted of Slaska type sausage produced in the Pilot Plant of Institute of Meat Technology at the Agricultural University of Poznań. The production process of model sausage was conducted following the generally adopted requirements for this type of meat products. Produced sausages differed in terms of applied additives (table 1).

Table 1. Amounts of applied additives

Sample	Citric acid [g·kg-1 batter]	Isoascorbic acid [g·kg-1 batter]	Sodium ascorbate [g·kg-1 batter]	Tocopherol [%]
A	0.30	0.50	-	0.02
B	0.30	-	0.50	0.02
C	0.40	-	0.40	0.01
D	0.20	0.10	0.60	0.03
E	0.20	0.60	0.10	0.01
F	0.40	0.40	0.10	0.03
G	0.20	0.50	-	0.03

After the completion of the production process sausages were vacuum packaged and stored at 4°C. The basic composition of sausages was determined following respective standards: protein content – PN-75/A-04018 [7], fat content – PN-ISO 1444:2000 [9] and water content – PN-ISO 1442:2000 [8]. In the course of storage the following parameters were determined in model sausages: changes in peroxide value [5], nitrite residue, pH-value and redox potential (Eh) [6]. Analyses were performed on the 1^st, 6^th, 11^th, 15^th, 20^th, 25^th and 29^th day after production.

All results were analyzed statistically with Microsoft Excel 2000 and STATISTICA 6.0 software. Results were interpreted at the level of significance α= 0.05.

RESULTS AND DISCUSSION

At the beginning of the experiment the basic composition of analyzed sausages was determined. It was found that contents of fat, protein and water were consistent with standard PN-A-82007/A1 [10] for this kind of sausages (Table 2).

Table 2. Basic composition of experimental sausages

Parameters [%]	Requirements of standard PN-A-82007/A1
protein     –    15.85	> 10.0
fat     –     17.18	< 30.0
water     –     64.23	< 73.0

Results were subjected to the two-way analysis of variance, where the source of variation was the variant of model sausage (A), i.e. the type and amount of applied additives, and storage time (B).

This analysis showed a highly significant effect of both the type and amount of applied additives and storage time on all assessed parameters. Table 3 presents the significance of analyzed dependencies.

Table 3. A list of F-values (α< 0.05)

Parameters	Source of variation	Fobserved	Frequired
changes in peroxide value	A	19.278	2.290
	B	173.168
nitrite residue	A	13.844
	B	1533.650
pH	A	86.147
	B	560.867
redox potencial	A	72.287
	B	1380.083

The determination of peroxide value belongs to the most frequently applied parameters defining fat quality. Results of analytical tests showed that with extending storage time of experimental sausages also peroxide values were increasing almost in all samples (Fig. 1). An exception in this respect were samples B and C (not containing isoascorbic acid), in which up to the 11th day of storage peroxide values were decreasing. Longer storage of these sausages caused a statistically significant increase of the analyzed index.

During the entire storage time (29 days) nitrite residue in model sausage was decreasing (Fig. 2). The highest nitrite residue was observed in sausage with the smallest amounts of citric acid and sodium ascorbate and with the highest addition of isoascorbic acid (sample E). A similar course of changes in nitrite residue was recorded in sausage G (without sodium ascorbate). In turn, sausage with no addition of isoascorbic acid, but with large amounts of sodium ascorbate and citric acid (sample C) was characterized by the smallest nitrite residue throughout storage.

Fig. 1. The effect of storage time on changes in peroxide value (PV) in experimental sausages

Fig. 2. The effect of storage time on changes in nitrite residue in experimental sausages

In commercial practice measurements of pH values are often taken in processed meats. In all produced model sausages the obtained results was found to be similar (Fig. 3). The initial pH value of analyzed samples ranged from 6.01 units for sausage C to 6.13 units for sample B.

During the first 20 days of storage a slight, but statistically significant reduction of pH values was recorded in analyzed samples. After that time an increase these values was found.

Redox potential is a property determined by many external and internal factors occurring during the processing and storage. Measurement of this important factor is rarely applied [14]. The Eh value of meat and its products is affected first of all by the presence of oxygen, thus the Eh value may be reduced by vacuum packaging or chopping and/or stuffing of batter under vacuum. The Eh value may be also reduced by the application of specific additives (especially ascorbic acid), thus improving the formation of colour and its stability in sausages [11, 12]. Based on the results of this experiment a similar course of changes in redox potential was found in all model sausages (Fig. 4). The lowest Eh value during 29-day storage was observed in sausage with the highest addition of isoascorbic acid and the smallest amount of citric acid and sodium ascorbate (sample E). In turn, up to the 20^th day of storage the highest value of this index was recorded for sausage A, while after the 20^th day – in sample C.

Fig. 3. The effect of storage time on changes in pH-value in experimental sausages

Fig. 4. The effect of storage time on changes in Eh values in experimental sausages

The obtained results also make possible to determine the dependence between pH-value and redox potential, as well as nitrite residue and peroxide values in Slaska type sausage.

Results of mathematical analysis did not show a statistically significant dependence between changes in peroxide value and pH-values.

In turn, a statistically significant dependence was found between nitrite residue and pH-value of experimental sausages. It was observed that the coefficient of determination for this dependence is low R² = 0.2392, but still significant (α = 0.0018). In analyzed sausages an increase in nitrite residue was observed with an increase in pH-value to 6.08. A further increase pH–value caused a reduction of nitrites in analyzed samples. This dependence is presented in Fig. 5.

Fig. 5. The correlation between pH-values and nitrite residue in experimental sausages

Fig. 6. The corelation between redox potential and nitrite residue in experimental sausages

Fig. 7. The correlation between redox potential and changes in peroxide values (PV) in experimental sausages

A statistically significant dependence was also found between nitrite residue and redox potential, and between changes in peroxide value and Eh in experimental sausages.

It was observed that nitrite residue was reduced with an increase of redox potential (Fig. 6).

In analyzed samples statistically highly significant dependencies were also found between redox potential value and changes of peroxide value (Fig. 7).

CONCLUSIONS

1. In all samples contents of basic components, i.e. protein, fat and water, were consistent with the respective standard (PN-A-82007/A1).

2. The kind and amount of applied additives and storage time had a statistically significant effect on obtained results of all analyzed indexes.

3. Nitrite residue decreased during the entire storage time.

4. Up to the 20^th day of storage a slight, but statistically significant reduction was observed in pH-values. Further storage caused a statistically significant increase in pH value of experimental sausages.

5. The sample with the highest addition of isoascorbic acid, but the smallest amounts of citric acid and sodium ascorbate was characterized by the lowest Eh value during 29 days of storage.

6. Statistically significant correlations were found between nitrite residue and pH-value as well as between nitrite residue and redox potential.

REFERENCES

1. Czerwińska D., 2006. W próżni [In vacuum]. Przeg. Gastronom. 5, 6-9 [in Polish].

2. Hęs M., Korczak J., 2007. Wpływ różnych czynników na szybkosc utleniania się lipidów mięsa [The effect of various factors on oxidation rate of meat lipids]. Nauka Przyr. Technol., 1, 1-11 [in Polish].
   http://www.npt.up-poznan.net/tom1/zeszyt1/art._3.pdf

3. Gajewska-Szczerbal H., 2005. Pakowanie mięsa i przetworów mięsnych. Cz.I. [Packaging of meat and processed meats. Part I]. Gosp. Mięsna 7, 6-9 [in Polish].

4. Kačeňák I., Dandar A., Sekretár S., 2005. Nowoczesne sposoby pakowania a ich wpływ na jakosc i trwałosc produktów [Modern methods of packaging and their effect on quality and shelf-life of products]. Przem. Spoż. 9, 20-25,40 [in Polish].

5. Ładoński W., Gospodarek T., 1986. Podstawowe metody analityczne produktów żywnosciowych [Basic analytical methods for foodstuffs]. PWN Warszawa [in Polish].

6. PN-ISO 3960 1996. Oleje i tłuszcze roslinne oraz zwierzęce. Oznaczenie liczby nadtlenkowej [Oils and plant and animal fats. Determination of peroxide value] [in Polish].

7. PN-75/A-04018 Produkty rolno-żywnosciowe – oznaczanie azotu metoda Kjeldahla i przeliczanie na białko [Agri-food products – determination of nitrogen according to Kjeldahl and conversion to protein] [in Polish].

8. PN-ISO 1442:2000 Mięso i przetwory mięsne. Oznaczanie zawartosci wody (metoda odwoławcza) [Meat and meat products. Determination of water content (reference method)] [in Polish].

9. PN-ISO 1444:2000 Mięso i przetwory mięsne. Oznaczanie zawartosci tłuszczu wolnego [Meat and meat products. Determination of free fat content] [in Polish].

10. PN-A 82007/A1 Przetwory mięsne. Wędliny [Meat products. Sausages] [in Polish].

11. Prost E., 1982. Metody laboratoryjnych badań sanitarnych żywnosci zwierzęcego pochodzenia [Methods of laboratory sanitary analyses of animal origin foodstuffs]. Wyd. AR. Lublin [in Polish].

12. Publikacja anonimowa, 1993. Zapobieganie zepsuciem mikrobiologicznym [Prevention of microbial decay]. Mięso Węd., 3, 40-42 [in Polish].

13. Publikacja anonimowa, 1997. Zastosowanie przeciwutleniaczy jako dodatków do przetworów mięsnych [The application of antioxidants as additives in processed meats]. Mięso Węd., 5, 80-81 [in Polish].

14. Rödel W., Scheuer R., 2000. Das Redoxpotential von Fleisch und Fleischerzeugnissen. 4. Erfassung von Qualitätskriterien bei Fleisch und Fleischerzeugnissen mit der Redoxpotentialmessung. [The redox potential of meat and meat products. 4. Determination of same meat and meat products quality parameters by redox potential controlling]. Fleischwirtschaft 5, 90-98 [in German].

15. Szukalska E., 2003. Wybrane zagadnienia utleniania tłuszczów [Selected problems of lipid oxidation]. Tłuszcze Jadalne vol. 38, 1-2, 42-60 [in Polish].

 

Accepted for print: 9.11.2007

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Agnieszka Bilska
Institute of Meat Technology,
University of Life Sciences in Poznań, Poland
Wojska Polskiego 31, 60-624, Poznań, Poland
phone: (+48 61) 846 72 61
email: abilska@au.poznan.pl

Krystyna Krysztofiak
Institute of Meat Technology,
University of Life Sciences in Poznań, Poland
Wojska Polskiego 31, 60-624 Poznan, Poland
phone: (+48 61) 848 75 09

Jacek Grzesiak
Institute of Meat Technology,
University of Life Sciences in Poznań, Poland
Wojska Polskiego 31, 60-624, Poznan, Poland

Wojciech Timm
Institute of Meat Technology,
University of Life Sciences in Poznań, Poland
Wojska Polskiego 31, 60-624, Poznan, Poland

Waldemar Uchman
Institute of Meat Technology,
University of Life Sciences in Poznań, Poland
Wojska Polskiego 31, 60-624, Poznań, Poland
ph: (+48 61) 846 72 61
fax: (+48 61) 846 72 54
email: waluchm@au.poznan.pl

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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.

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