THE QUALITY OF FERMENTED RAW SAUSAGES MANUFACTURED USING PORCINE BLOOD PLASMA

Jan Pyrcz¹, Ryszard Kowalski¹, Piotr Konieczny², Bożena Danyluk^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 principal aim of this study was to determine technological possibility of utilization of condensed porcine blood plasma containing about 21% of protein for production of "Salami" type raw sausages.

These studies were based on evaluation of dynamic of fermentation changes and sensory quality of final products.

Four variants of blood plasma preparations were applied in the study, it means: fresh condensed plasma, fresh condensed plasma modified microbiologically with addition of lactic acid bacteria cultures mixture, fresh condensed blood plasma modified with addition of liquid smoke preparation and dried blood plasma preparation after its water rehydration to the level ensuring total protein content of 21%.

Sausages were next analyzed for content of lactic acid, total amount of volatile low fatty acids, pH-value, content of ethyl alcohol and their sensory acceptance.

The relationships between analyzed chemical quality characteristics and sensory acceptability of experimental sausages were found.

Key words: raw sausages, blood plasma, quality, fermentation, sensoric .

INTRODUCTION

The essence of fermented raw sausages production is to process unstable meat and fat raw material into final product characterized by high resistance against spoilage, specific taste and aroma profile, red colour and high nutritional and energy value [4, 5, 8, 13, 18].

Proper selection of meat and fat raw material as well as basic technological operations indicate, that raw sausages production based on controlling biochemical processes of enzymatic and microbiological origin. The final quality of fermented raw sausages depends on dynamic of changes of carbohydrate, protein and fat fraction. Due to their intensity, these changes affect more or less onto formation of sensoric, rheological and microbiological properties of final product [1, 2, 4, 5, 9, 10].

Beside traditional technologies of raw sausages production, non-meat raw material plays larger and larger role in the meat industry. Animal or plant origin protein preparations belong to such raw material. Native blood plasma or processed blood plasma proteins using condensation, precipitation, structuring and co-precipitation i.e. with milk proteins are well accepted and relatively common used compounds of selected meat products recipes [3, 6, 11, 12, 21, 22].

As now, utilization of slaughter animal blood plasma is mainly limited to its application in production of fine comminuted cooked sausages, pate and some sorts of canned meat or ready to cook products [11, 12, 20, 21, 22]. The wider utilization of animal blood plasma also in production of raw sausages seems highly justified by high biological and nutritional value of that proteins, their proper functionality and not complicated processing methods [3, 21, 22, 23 ].

Literature data analysis related to possible utilization of porcine blood plasma in raw sausage production indicated, that up to now this problem has been studied only fragmentally, and the obtained results mostly describing model experiments, were publish in small numbers of scientific publications.

In face of this, a question should be finding the effect of porcine blood plasma proteins onto quality of raw sausages and also about the usefulness of utilization of condensed plasma as recipe compound for this type of meat products. It is well known, that the raw sausages quality is determined first of all by biophysico-chemical changes of raw material resulted from production and storage processes. Since functionality of blood and meat tissue proteins are similar, it can be expected, that application of condensed porcine blood plasma in production of raw sausages will be reasonable and possible.

The aim of this study was to determine technological possibility of utilization of condensed porcine blood plasma containing about 21% of protein in production of "Salami" type raw sausages. These studies should be based on evaluation of fermentation changes and sensory quality of final products.

MATERIALS AND METHODS

Experimental fermented "Salami" type sausages were produced from lean pork, lean beef and pork back fat (Table 1). Two stages of experiment were planned:

a - optimization of raw material composition with the part of meat tissue substituted by the proper amount of condensed porcine blood plasma containing 21% of protein.

Four variants of blood plasma preparations were applied in the study:

1) fresh condensed plasma - CPBP,
2) fresh condensed plasma modified microbiologically with addition of lactic acid bacteria cultures mixture obtained from Microbiological Culture Collection in Olsztyn,
3) fresh condensed blood plasma modified with addition of a liquid smoke preparation,
4) preparation obtained from dried blood plasma preparation after its dehydration with water to the level ensuring total protein content of 21%.

The blood plasma was preliminary condensed up to 21% of protein content (as value comparable with protein content in lean meat) by the using vacuum evaporator during about 20 min at temperature 42°C.

b - manufacturing five variants of model sausages and checking their most important parameters and looking for the influence used substitution onto the consumer quality of obtained sausages.

Initial experiments indicated that optimal meat substitution level with proposed variants of plasma preparations should not exceed 9%, and higher levels of such substitution may caused significant worsening sensory quality of obtained raw sausages.

Meat used for production were first sliced in pieces of 100-150 g and kept frozen at -12°C, while back fat was 2 cm diced and frozen at -18°C. Raw material in this way was next comminuted using chopper and blended with spices due to amounts given in Table 1. The following spices were applied for production: curing salt (2.5%), natural black paper (0.15%), hot paprika (0.10%), nutmeg-apple (0.2%), saccharose (2.0%) and BACTOFERM F-RM -52 (Lactobacillus curavatus, Staphylococcus carnosus) preparation in amount of 0.25 g/kg of meat, purchased from Chr. Hansen, Polhein Company.

Table 1. Raw material composition of experimental raw sausages [%]

Raw material	Sausage variant
	A	B	C	D	E
Pork meat	40.0	35.5	35.5	35.5	35.5
Beef meat	30.0	25.5	25.5	25.5	25.5
Back fat	30.0	30.0	30.0	30.0	30.0
Condensed porcine blood plasma - CPBP	-	9	-	-	-
CPBP microbiologically modified	-	-	9	-	-
CPBP modified by the use of of liquid smoke preparation	-	-	-	9	-
Dry porcine blood plasma rehydrated with water	-	-	-	-	9

The next, protein casings with diameter of 60 mm were stuffed with ready to use meat batter and ripped in air conditioning chamber at 23°C and relative humidity of 90-95% (1 day) and at 17-18°C by relative humidity of 85-90% for next 4 days. After 5 days of preliminary ripening sausages were smoked using cold smoke at 20°C for 1 day. For next thirty days of post-production ripening all experimental sausages were kept also in air conditioning chamber at 14-15°C and air relative humidity of 80-85%.

A sausage manufactured without modified blood plasma addition was used as reference one (sausage A).

Sausages were next analyzed for:

1) content of lactic acid - by the modified HPLC method described by Miyagodzi et al. [14],
2) the total amount of volatile low fatty acids - expressed as acetic acid [7],
3) the pH-value - using pH-meter with combined electrode,
4) ethyl alcohol content using enzymatic method [16],
5) their sensoric acceptance - using 5-point hedonic scale (cross section colour, taste, flavour and consistency were evaluated).

All parameters of experimental sausages were determined directly after production (it means in batter) as well as for sausage samples collected at 5, 10, 20 and 30 days after stuffing.

The experiment was repeated 3 times, and statistical analysis of obtained results were conducted.

RESULTS AND DISCUSSION

Dynamic of fermentation process

One of the important products resulted from processes associated with production of fermented raw sausages is lactic acid representing fraction of acid compounds. Content of lactic acid in raw sausages is not stable and depends on sausage type and degree of sausage ripeness (Table 2).

Table 2. Content of lactic acid in raw fermented sausages, mean values, n=9

Variant of sausage	Time of storage [days]					LSD0.05
	0	5	10	20	30
A	101.18 aA	140.11 bcdB	207.41 bdC	203.16 eD	189.53 aE	8.52
B	97.46 aA	140.13 bcdB	214.95 bdC	216.86 bdCD	193.03 bdE
C	116.91 bA	148.38 bcB	231.70 cC	239.42 cCD	209.44 cE
D	101.58 aA	141.06 bB	213.76 bC	217.80 bC	198.27 bD
E	100.38 aA	130.38 aB	202.64 aC	192.13 aD	183.07 aE

Note: identical small letters within the columns means lack of significant differences at p< 0.05, identical capital letters within rows - lack of significant differences at p< 0.05

In all variants of experimental sausages changes in content of lactic acid were most intensive between 5 and 10 day of post-production ripening. It was found that in control sausage (A) and in the sausage manufactured with addition of rehydrated plasma preparation (E), the maximal concentration of lactic acid was observed at 10 day of ripening, while remaining sausages (B, C and D) demonstrated maximum value of lactic acid concentration at 20 day of sausage ripening. The maximal content of lactic acid (239.42 mg/100 kg) was found for sausages made with microbiologically modified condensed blood plasma (C).

But relative final increments (as percentage to the initial time) of lactic acid content was similar for all variants of investigated sausages. It means that used preparations have not significant influence on these kind of fermentation.

The changes of content of volatile fatty acids in investigated sausages are presented in Table 3.

Table 3. Content of volatile fatty acids in raw fermented sausages, mean values, n=9

Variant of sausage	Time of storage [days]					LSD0.05
	0	5	10	20	30
A	5.04 acA	16.05 beB	19.76 adC	14.96aD	13.52aeE	1.13
B	5.00 acA	19.95 cdB	20.67 bdBC	20.84 dBC	14.87 dD
C	7.37 bA	20.22 cB	24.81 cC	26.35 cD	20.58 cBE
D	5.04 aA	16.89 bB	21.59 bC	22.02 bCD	17.17 bBE
E	4.91 aA	15.61 aB	19.53 aC	14.49 aBD	12.70 aE

Note - the same as in Table 2.

Dynamic of these changes is similar to pattern obtained for changes of lactic acid content. Maximal concentration both of lactic acid as well as total amount of volatile low fatty acids for sausages coded A and E were observed after 10 days of ripening, and for remaining sausages (B,C and D) it was after 20 days of ripening.

This similarity of the changes of main acid compounds in investigated sausages confirm that homo- and heterofermentative processes occur simultaneously during ripening process. These data confirm also that carbohydrate changes are one of most important factors influencing taste and odour profile of fermented raw type sausages [1, 2, 4, 14, 15, 18].

The differentiation of acidity (pH) of experimental raw sausages represents statistically significant function both of raw material composition (sausage variant) as well as time of ripening (Fig. 1). It is connected with the observed changes of contents of lactic acid and volatile low fatty acids.

Fig 1. Change in pH of raw fermented sausages

Process of pH-value changes in experimental raw sausages can be divided into two periods: the first one was connected with acidity increasing (milieu acidation) and occurred till 20 day of ripening, and second period when slightly alkalization of milieu was observed. In first period step by step acidation in all variants of experimental raw sausages was observed, and maximal pH value was found in case of sausage C manufactured with addition of porcine blood plasma, microbiologically modified with lactic acid bacteria strains. Therefore, it is recommended to try to find close correlation between content of acid compounds of fermentation (lactic acid and volatile low fatty acids) and pH value of experimental sausages.

Alkalization of experimental sausages is supposed to be caused (among other) by oxidation of acid fermentation products and protein fraction changes occurring between 10 and 20 day of sausage ripening [4, 10, 11].

Sensoric quality of raw sausages, and in particularly their flavour is determined also by neutral products of carbohydrate fermentation, it means mainly by ethanol content [1, 17, 19].

Ethanol content changes occurring during production and storage of raw sausages are presented in Table 4.

Table 4. Content of ethyl alcohol in raw fermented sausages, mean values, n=9

Variant of sausage	Time of storage [days]					LSD0.05
	0	5	10	20	30
A	7.57 aA	67.80 bB	127.46 bdC	108.48 deD	55.78 deE	6.62
B	7.88 aA	62.50 bB	120.13 bC	110.48 bdD	56.40 bdE
C	8.73 aA	95.72 cB	145.15 cC	142.83 cC	83.70 cBD
D	7.61 aA	65.25 bB	125.95 bC	115.40 bD	57.25 bBE
E	7.53 aA	58.20 bB	109.50 aC	83.40 aD	50.70 dE

Note - the same as in Table 2.

Also in this case, similar to content of acid fermentation products changes, it was found univocally that the content of ethanol depends first of all on sausage variant as well as how far production and storage of final sausages are advanced.

The highest ethanol content was found in the sausage C (manufactured with microbiologically modified blood plasma), and the maximal value of this compounds was observed at 20 day of ripening. In remaining experimental sausages dynamic of ethanol content changes was similar, however maximum value of ethanol concentration was found in 10 day of ripening. Therefore, dynamic of ethanol accumulation in tested sausages was most intensive during production and first 10-20 days of production ripening.

Presumably these steps of production have critical character and influence on consumer properties of final raw sausages.

Evaluation of sensoric acceptability of the experimental raw sausages

Obtained results indicate that application of four various blood plasma variants as substitutes of meat tissue did not change overall sensoric acceptability of the experimental raw sausages. Technological variabilities applied in this stage of study caused differentiation of partial sausage quality characteristics only, like: cross section colour, taste, flavour and consistency (Table 5).

Table 5. Sensoric palatability raw fermented sausages (in hedonic scale), mean values [n=15]

Parameter	Variant of sausage	Time of storage [days]					LSD0.05
		0	5	10	20	30
Cross section colour	A	4.27 bA	4.50 abcA	4.47 abcdA	4.30 aA	4.27 aA	0.47
	B	4.23 bA	4.47 bcA	4.45 abcdA	4.33 aA	4.23 aA
	C	4.27 bA	4.58 bcA	4.50 abcA	4.33 aA	4.27 aA
	D	4.27 bA	4.50 abA	4.43 abA	4.40 aA	4.27 aA
	E	3.67 aA	4.00 aA	3.90 aA	3.90 aA	3.67 aA
Taste	A	3.90 aA	4.17 aA	4.20 abcA	4.15 aA	3.90 aA	0.50
	B	4.03 aA	4.13 aA	4.27 abcA	4.23 aA	4.03 aA
	C	4.15 aA	4.43 aA	4.73 abA	4.26 aA	4.15 aA
	D	4.07 aA	4.31 aA	4.37 aA	4.15 aA	4.07 aA
	E	4.08 aA	4.07 aA	4.13 aA	3.95 aA	4.08 aA
Odour	A	4.07 aA	4.17 aA	4.17 aA	4.13 abA	4.07 aA	0.54
	B	3.80 aA	4.07 aA	4.17 aA	4.20 abA	3.80 aA
	C	4.20 aA	4.50 aA	4.57 aA	4.50 abA	4.20 aA
	D	4.10 aA	4.20 aA	4.27 aA	4.23 aA	4.10 aA
	E	3.90 aA	3.97 aA	4.07 aA	3.93 aA	3.90 aA
Consistency	A	4.00 aA	4.17 aA	4.20 aA	4.23 aA	4.00 aA	0.57
	B	4.06 aA	4.07 aA	4.23 aA	4.36 aA	4.06 aA
	C	4.00 aA	4.23 aA	4.26 aA	4.23 aA	4.00 aA
	D	3.80 aA	4.13 aA	4.20 aA	4.17 aA	3.80 aA
	E	4.13 aA	4.23 aA	4.26 aA	4.30 aA	4.13 aA

Note - the same as in Table 2.

Among five variants of experimental sausages, the best organoleptic quality was found in case of sausage made using condensed blood plasma modified with lactic acid bacteria strains (code C). The aroma and the taste of this sausage were found markedly better, while cross section colour and consistency were improved a little be only. Taste of the sausage C was evaluated about 0.3 point higher in comparison to the control sausage A. Markedly better taste and flavour was also found for sausage D manufactured with addition of fresh condensed blood plasma modified with liquid smoke preparation. Sensoric quality of sausage E containing rehydrated blood plasma preparation was evaluated significantly lower in comparison to the remaining sausage samples. After 30 days of sausage ripening, the taste and cross section colour of this sausage variant was evaluated 0.20 and 0.40 point lower, respectively in comparison to the control sausage.

Sensoric quality of experimental raw sausages is connected with dynamic of changes of chemical compounds in meat batters. Using multiple regression model it was found i.e. that sensory evaluation of taste was affected by changes of each of three determined compounds like lactic acid, volatile low fatty acid and ethanol content. It is possible to describe these relationships with mathematical functions of the third degree, where the lactic acid content demonstrates main influence on the taste of tested sausages (Fig. 2, 3 and 4). Relatively low determination coefficients of above mentioned relationships indicate that the sensoric acceptability of raw sausage taste was affected also by other non determined compounds occurring in the meat batter. This thesis corresponds well with similar research results reported in the literature [5, 18, 19].

Fig 2. Correlation between lactic acids content and the sensory acceptance of taste of experimental sausages

Fig 3. Correlation between ethanol content and the sensory acceptance of taste of experimental sausages

Fig 4. Correlation between volatile fatty acids content and the sensory acceptance of taste of experimental sausages

In this study was also found that the sensory quality of raw fermented sausages, manufactured with the addition of condensed porcine blood plasma, was also affected by ripening time. The maximal acceptability of taste and flavour for all examined sausages was achieved at 20 day of post production ripening, while their optimal colour and consistency was observed at 20 and between 10 and 20 day of ripening, respectively.

Also this relationship can be expressed with mathematical regression models. For taste as a function of sausage ripening time it has been showed in Table 6.

Table 6. Relationship between taste of raw fermented sausages and time of their storage

Variant of sausage	Regression equation	Coefficient of determination R2
A	y = 3.674 + 0.0591x - 0.00154x2	0.790
B	y = 3.869 + 0.0348x - 0.00076x2	0.986
C	y = 3.609 + 0.1193x - 0.0032x2	0.956
D	y = 3.805 + 0.0653x - 0.0018x2	0.939
E	y = 3.974 + 0.0206x - 0.0007x2	0.712

When: y = sensoric evaluation of taste in hedonic scale x = time of storage [days]

To summarize results obtained in this study, it should be also take into consideration that using condensed blood plasma in production of fermented raw sausages is not only technologically motivated by improvement of sensory quality of final meat product but also by the possibility to utilize such valuable raw material like blood plasma protein. The economical aspects of this substitution are also very interesting.

CONCLUSIONS

1. Application of the four condensed porcine blood plasma preparations as a substitute of meat tissue in the production of fermented raw sausages don´t alter the character of their biophysico-chemical and sensoric changes.

2. The use of condensed blood plasma preparations affects onto changes both of acid as well as neutral products of fermentation.

3. Sensory evaluation of experimental sausages indicates that the highest acceptability (under condition of this study 30 days of ripening) demonstrated sausages manufactured with the addition of 9% condensed blood plasma modified with lactic acid bacteria strains.

4. Close relationship between analyzed chemical characteristics and results of sensory acceptability of experimental sausages was found. The relationship can be presented by elaborated mathematical equations.

5. Utilization of condensed porcine blood plasma modified with lactic acid bacteria in production of fermented raw sausages is technologically motivated by:

• potentially higher stability of final product resulted from its higher acidation,

• improvement of overall sensory acceptability because of higher content offermentation products.

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Jan Pyrcz
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: janpyrcz@up.poznan.pl

Ryszard Kowalski
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: kowalski@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

Bożena Danyluk
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

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