THE EFFECT OF FUNCTIONAL BLENDS ON SHELF LIFE OF MODEL PROCESSED MEATS

Agnieszka Bilska¹, Krystyna Krysztofiak¹, Waldemar Uchman¹, Piotr Konieczny², Iwona Fabianowska-Stasiak¹, Piotr Pipowski^1
1 Institute of Meat Technology, University of Life Sciences in Poznań, Poland
² Department of Food Quality Management, University of Life Sciences in Poznań, Poland

ABSTRACT

The aim of the study was to investigate the effect of selected functional blends on shelf life of model meat products. Analyses showed that total microbial counts in functional blends did not have a significant effect on the variation of infection in case of sausages produced with their addition. However, in comparison to reference products sausages with a share of analyzed blends exhibited a significantly shorter shelf life. The presence of blends in sausages had a significant effect on the course of lipid changes and contributed to the acceleration of oxidation processes during sausage storage. Obtained results may be useful when determining admissible shelf life of sausages produced with an addition of analyzed functional blends.

Key words: functional blends, shelf life, sausages, quality, additives.

INTRODUCTION

At present the primary role of herb spices in foodstuffs is to make them more attractive and ensure variety, while the basic aim of their use is to modify flavour attributes. However, herbs serve many different functions; apart from the fact that they aromatize the product, improve appetite, stimulate the functioning of the alimentary tract of the consumer and frequently extend microbial stability and have an antioxidant action on the product [1,7,9,11].

In comparison to individual blends constitute the first stage in the strive to obtain homogenous preparations with a specific quality standard. In order to provide constant aromatization capacity extracts and essential oils are added. The size of the packaging, adapted to a specific batter weight, facilitates their storage and appropriate dosage [9,11,21] Mixes of appropriately selected herbs with a standard comminution rate, prepared at constant proportions suitable for specific products, are sometimes called blends. If the aromatizing preparation contains substances other than herb ingredients, then depending on the composition of the preparation two types of such mixes are distinguished. Seasonings are mixes of spices with an addition of such ingredients as table salt, sodium glutamate, yeast hydrolyzates, citric acid and other flavour enhancers. Herbs in a seasoning have to account for at least 60%, while salt content needs to be below 5%. Functional blends contain herbs and their components (over 60%), active flavour additives as well as technologically active substances, such as ascorbic acid, sorbate, etc. [9,23].

The spectrum of microorganisms found in spices is very wide, which results from the specific chemical composition of essential oils, the geographical region as well as plant cultivation conditions, storage conditions and duration, etc. Characteristic microflora of spices consists primarily of aerobic spore-forming bacteria from the genus Bacillus and anaerobic bacteria from the genus Clostridium as well as moulds from the genera Aspergillus, Penicillium, and occasionally also Rhizopus and Fusarium. Among spore-forming bacteria the most serious hazard is posed by G[+] Bacillus cereus and Clostridium perfringens, which may cause food poisoning [9]. The spice infection rate may be very high. Total microbial count in some types of spices may be as high as 10⁸ CFU·g^-1. The level of moulds is slightly lower, amounting to 10¹–10⁵ CFU·g^-1 [9,11,14,21].

The degree of microbiological contamination of spices needs to be controlled. Microbiological requirements in relation to spices concern most frequently the following groups of microorganisms: total bacterial count or the number of spores of mesophilic aerobic bacteria in 1 g (up to 10⁵), the count of moulds in 1 g (up to 10³), coli-form bacteria (not detected in 0.001 g), anaerobic spore-forming bacilli (not detected in 0.01 g), Salmonellae (not detected in 25 g) and Staphylococcus aureus (not detected in 0.10 g) [9,14,21].

Batter and ready-to-eat meat products are advantageous environments for most microorganisms. As a consequence of their development disadvantageous physical and chemical changes take place in the product. Acidity [22] and redox potential of the product increase or decrease [4,18,22]. This results in the acceleration of oxidation processes and deterioration of sensory quality of products [10,13,15,20,22]. Although in the course of sausage production different safeguards are applied, such as e.g. the addition of preservatives (nitrite, salt) and thermal processing, their effectiveness in relation to individual spices and characteristic microorganisms infesting them varies [2,3,6,15,20]. Thus it is essential to perform tests determining the effectiveness of parameters of the technological process applied in practice in terms of the reduction of microbial counts in final products.

The aim of the presented study was to verify the effect of ready-to-use functional blends developed for the production of different types of sausages on the microbiological contamination rate and the course of oxidative changes in model sausages produced with their use.

MATERIAL AND METHODS

Experimental material consisted of model sausages produced from pork class II (75%) and fine fat (25%) with an addition functional blends applied in the amounts recommended by the manufacturer, i.e. from 0.64 to 1%, and sodium nitrite at 150 ppm. The raw material was ground using a 8 mm mesh size, mixed with additives and stuffed into natural porcine casings. Sausages were scalded until the temperature of 69^οC was obtained in the centre of the link and cooled under cold running water until 20^οC was recorded. Final products were stored at 0–4^οC.

Five model sausages were tested (Table 1), which differed in the type of the applied blends, while sausage without this addition constituted the reference sample.

Table 1. Types and amounts of functional blends in experimental sausages

Sample no.	Functional blends to be used in	Amount of blend [kg·100 kg-1 raw material]
1	Grillowa ekstra sausage	0.71
2	Pieprzowa sausage	1.00
3	Śląska sausage	0.64
4	Kabanos type sausage	0.67
5	Pasztetowa sausage	0.67
6	Control	0.00

As declared by the manufacturer, each blend, apart from a set of natural spices characteristic for a given assortment, contained glucose, monosodium glutamate (E621) as a flavour enhancer, ascorbic acid (E300) as an antioxidant and table salt.

During 32-day storage model sausages were tested 6 times, determining total microbial counts, peroxide values and active acidity. Moreover, total microbial count was determined in individual functional blends.

Microbiological analyses of total microbial counts in functional blends and determinations of total microbial counts in sausages were performed according to standard PN-A-82055-6 [17]. Peroxide value (PV) was determined according to standard PN-ISO 3960. Peroxide value was expressed in active oxygen miliequivalents in 1 kg sample [16]. Changes in active acidity in samples were also recorded (10.00 g sample were homogenized for 1 min with 50 ml water, after which pH was measured) [12].

All results were analyzed statistically. Two-way analysis of variance with replications was conducted and regression were identified.

RESULTS AND DISSCUSION

Total microbial count in functional blends
In order to determine the microbiological quality of analyzed blends total counts of aerobic microorganisms were determined and the results are presented in Table 2. According to the binding regulations foodstuffs have to meet specific conditions concerning the type and level of microorganisms present. It is commonly assumed that total count of mesophilic aerobic microorganisms should be as low as possible and not exceed 10⁶. Thus functional blends contamination at 10⁵–10⁶ CFU·g^-1 may be considered a warning sign, which may have an effect on the microbiological contamination of the final product. However, since tested blends were added in amounts not exceeding 1%, their contamination does not have to drastically increase the contamination of the final product [15].

Table 2. Total count of aerobic microorganisms in tested blends

No.	Tested blends name	Count CFU·g-1 (·105)
1	Grillowa ekstra sausage	10.0
2	Pieprzowa sausage	8.4
3	Śląska sausage	11.0
4	Kabanosy sausage	5.7
5	Pasztetowa sausage	13.0

Changes in total microbial counts during sausage storage
Based on the conducted two-way analysis of variance it was found that the type of sample and storage time had a statistically significant effect on changes in total microbial counts (for α = 0.05) in sausages. This is presented in Table 3.

Table 3. F values (for α = 0.05)

Source of variation	F(calculated)	F(tab.)
Type of sample (A)	31.319	2.44
Storage time (B)	206.438	2.32

Means for total microbial counts are presented in Table 4.

Table 4. Means of total microbial counts depending on the type of sausage (A) and storage time (B)

Type of sausage	Time of storage [days]
	1	8	13	20	26	32
Grillowa	2.4·103	3.6·103	5.4·103	9.0·103	1.3·106	2.7·106
Pieprzowa	4.2·103	5.5·103	6.1·103	6.3·104	8.1·105	5.4·106
Śląska	4.5·103	7.1·103	7.4·103	6.1·104	1.3·106	3.8·107
Kabanosy	2.5·103	2.9·103	3.4·103	4.6·105	1.9·106	5.6·106
Pasztetowa	6.9·103	5.9·103	8.1·103	8.8·104	9.5·105	4.9·107
Control	4.9·102	6.2·102	1.8·103	7.2·103	4.9·104	2.7·105

It results from data presented in Table 4 that the admissible total count of aerobic bacteria, in case of analyzed products amounting to 1·10⁵ CFU·g^-1 [8,10,15,22], was recorded in samples after 20 days (kabanos type sausage) or 26 days of storage (grillowa, pieprzowa, śląska and pasztetowa sausage). Sausages control had the same levels after 32-day storage. The effect of storage time of model sausages on changes in the total bacterial count, expressed as lg, is presented in Fig.1. The results are presented as: lg(N_t/N₀),

where:
N_t – number of counts in time “t”
N₀ – number of counts on the start of experiment (t = 0).

Fig. 1. Changes in total bacterial count in tested experimental sausages

Presented results indicate that with the passing storage time under adopted temperature conditions the value of total bacterial count increased gradually. Sausage control throughout the entire storage time differed significantly from the other processed meat products. It was characterized by the lowest microbiological contamination. Thus analyzed blends are sources of an additional microbiological contamination of the product, which is not reduced during the technological process. During storage the prolification dynamics of bacteria in sausages produced with an addition of tested blends were similar in all samples and have a small but significant effect on the growth rate of bacteria. Results may prove useful when determining shelf life of sausages produced with tested blends.

Changes in peroxide value in model sausages
Based on the two-way analysis of variance it was found that in stored sausages both analyzed variation factors had a statistically significant effect on peroxide value (for α = 0.05). Table 5 presents results of statistical analysis. Fig. 2 below presents obtained means.

Table 5. F values for significance level α = 0.05.

Source of variation	F(calculated)	F(tab.)
Type of sample (A)	21.710	2.44
Storage time (B)	63.149	2.32

Fig. 2. Changes in peroxide value during storage of model sausages

Results indicate that during 32-day storage peroxide value increased gradually, but this growth dynamics varied. In sausage control a statistically significant increase in peroxide value was observed after 13 days. An identical result was recorded for sausages to which the grillowa and kabanos type blends were added. In turn, in sausage with the pasztetowa type blend a statistically significant increase in peroxide value was found as early as after 5 days. A slightly better result, i.e. a statistically significant increase in peroxide value after 8-day storage, was recorded in sausages with the pieprzowa and śląska type blends. This indicates that individual types functional blends exhibited a diverse, but always pro-oxidative effect on the course of the oxidation process. The pasztetowa type blend accelerated oxidation in the model sausage at the highest rate. A slightly weaker pro-oxidative action in relation to reference sausage was observed for the pieprzowa and śląska type blends, while the grillowa and kabanos type blends exhibited the slowest effect. After 32-day storage statistically significant differences in peroxide value were found in all sausages.

Results do not show a direct statistically significant relationship between the level of microbiological contamination and the rate of lipid oxidation in tested samples. Thus it may be assumed that lipid oxidation rate in sausages is affected by the specific composition and proportions of ingredients in analyzed blends [9].

Changes in active acidity of sausages

Based on the two-way analysis of variance it was found that only the type of sample had a statistically significant effect (for α = 0.05) on pH value of stored sausages (Table 6).

Table 6. F values (for α = 0.05)

Source of variation	F(calculated)	F(tab.)
Type of sample (A)	9.843	2.44
Storage time (B)	0.481	2.32

The obtained results are presented in Fig. 3.

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

Within the first 24 h after production pH in sausages with functional blends added was statistically significantly higher than in sausage control. The upward trend for pH values was observed only in sausage with an addition of the grillowa type blend. On day 32 of storage pH in this sausage was statistically significantly higher than in the other sausages, in which final pH was similar to the initial level. It may be assumed that lactic acid bacteria did not develop during sausage storage.

CONCLUSIONS

1. Sausages produced with an addition of functional blends were characterized by shorter storage life than the reference sausage.

2. Total microbial count in functional blends did not have a statistically significant effect on the contamination rate of individual sausages produced with their addition.

3. The type of functional blends had an effect on the lipid oxidation rate in sausages.

4. Results may prove useful when determining admissible shelf life of analyzed sausages produced with an addition of functional blends.

REFERENCES

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Accepted for print: 22.04.2008

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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

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

Piotr Konieczny
Department of Food Quality Management,
University of Life Sciences in Poznań, Poland
Wojska Polskiego 31, 60-624 Poznań, Poland
email: pikofood@au.poznan.pl

Iwona Fabianowska-Stasiak
Institute of Meat Technology,
University of Life Sciences in Poznań, Poland
Wojska Polskiego 31, 60-624, Poznań, Poland

Piotr Pipowski
Institute of Meat Technology,
University of Life Sciences in Poznań, Poland
Wojska Polskiego 31, 60-624, Poznań, Poland

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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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