The influence of the addition of mechanically deboned poultry meat on the rheological properties of sausage

Journal of Food Engineering 68 (2005) 185–189 www.elsevier.com/locate/jfoodeng The influence of the addition of mechanically deboned poultry meat on t...
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Journal of Food Engineering 68 (2005) 185–189 www.elsevier.com/locate/jfoodeng

The influence of the addition of mechanically deboned poultry meat on the rheological properties of sausage Fabiane Guerra Daros a, Maria Lucia Masson a

a,*

, Sandro Campos Amico

b

Food Technology Post-graduation Program, Federal University of Parana, P.O. Box 19011, 81531-990 Curitiba-PR, Brazil b Department of Mechanical Engineering, Federal University of Parana, Curitiba-PR, Brazil Received 3 November 2003; accepted 26 May 2004

Abstract Addition of mechanically deboned poultry meat (MDPM) as an ingredient in the formulation of sausage is recent in Brazil. This paper addresses the influence on rheological characteristics of sausage when meat is increasingly replaced (0–100%) by MDPM in sausage formulation. A universal testing machine was used to obtain direct measurements and quantify resistance of sausage to tensile and compression in tests carried out at 20 C and with a strain rate of 50 mm/min. The results showed a strong influence of the MDPM content on the measured mechanical properties, namely compressive and tensile strength. Besides, it has been found that additions of MDPM higher than 60% in the sausage formulation caused significant rheological behavior alteration.  2004 Elsevier Ltd. All rights reserved. Keywords: Sausage; Mechanically deboned poultry meat; Mechanical properties

1. Introduction The use of mechanically deboned poultry meat (MDPM) in the formulation of sausage is considered recent in the food industry since it only started in the 60Õs when there was a strong tendency to replace red meat for healthier white meat in industrialized countries and also due to the lower price of the latter compared to other kinds of meat. In Brazil, the average consumption of meat increased around 32% between 1991 and 1996, whereas the consumption of white meat increased by 62%, with chicken being responsible for most this large increase due to its comparative low price (Baldini, 1990). The preparation of varied chicken products, such as special cuts, sausage

* Corresponding author. Tel.: +55 41 361 3192; fax: +55 41 361 3674. E-mail addresses: [email protected] (F.G. Daros), [email protected] (M.L. Masson), [email protected] (S.C. Amico).

0260-8774/$ - see front matter  2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.jfoodeng.2004.05.030

and others, have contributed to the production of residues such as bones with adhering meat that still generate the raw material for mechanically deboned poultry meat (MDPM). According to the current Brazilian law (Instruc¸a˜o Normativa, 2000) MDPM is defined as meat which has been obtained by mechanical processing, chopping and separation of bones from animals, such as chicken, beef and pork, to be used in the formulation of specific meat products. It is also stated that only bones, carcasses or parts of carcasses, which have been approved for human use by the SIF (Brazilian Federal Inspection Service) should be used, thereby excluding head, feet and legs. The physicochemical and microbiological standards are also specified and the denomination mechanically deboned meat should be followed by the animal species from which it was taken from. The mechanical process of removing meat from the bone causes cell breakage, protein denaturation and increase in lipids and hemme groups and poorer mechanical properties. MDPM has a jelly consistency and high

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fat levels, being mainly used in the preparation of emulsion products, where it is usually added with colorants (Field, 1976; Froning, 1976). The most used raw materials are back, necks and thighs either from the initial carcass or after removal of most meat. The composition of MDPM as determined by many authors (Ang & Hamm, 1982; Babji, Froning, & Satterlee, 1980; Duranti & Cerletti, 1980; Hamm & Young, 1983) shows large variations in MDPM chemical composition as a function of raw material composition. The functional characteristics of most interest are jelly consistency, water retention and ability to emulsify fat. The choice of raw material has a marked influence on these MDPM properties, being specially related to water retention ability and emulsification properties (Orr & Wogar, 1979). The main applications of MDPM are in products such as sausage and salami, which do not require a fibrous texture but demand emulsion stability, and also benefit from the MDPM natural color. The addition of MDPM affects physical, microbiological and sensorial properties of the products. Researchers such as Brennan and Bourne (1994) Jones, Dransfield, and Crosland (1989), and Ripoche, Le Guern, Martin, Taylor, and Vendeuvre (2001) evaluated the influence of parameters such as processing temperature, salt content and composition of meat and fat on the mechanical properties of food. Yang and Froning (1992) prepared sausage with 100% MDPM content and studied the influence of MDPM on mechanical properties. Gimeno, Ansorena, Astiasaran, and Bello (2000) carried out direct texture measurements via compression tests on different kinds of sausage. Crehan, Hughes, Troy, and Buckley (2000) studied the influence of fat content on physical and sensorial properties of sausage using compression tests. The modern food industry practices demand evergrowing quality standards, which also include mechanical properties of solid and viscoelastic products, vital when considering transport, storage and preparation prior to consumption. The relatively recent use of MDPM in sausage and the tendency to increase MDPM content causes concerns regarding sausage microbiological, nutritional and structural properties. The aim of this work is to verify and quantify the influence of MDPM content on sausage mechanical properties, namely tensile and compression strength, and to identify the maximum acceptable content of MDPM to preserve the sausage structure.

flavor enhancer––monosodium glutamate, a red natural colorant, onion and smoke and pepper flavors. In all experimental batches, the total weight of beef, pork, pork fat and MDPM was kept constant and equal to 1500 g. The amount of the other ingredients were always constant and equal to: ice (225 g), salt (30 g), cassava starch (30 g), sodium nitrate (5 g), stabilizer (4 g), antioxidant (4 g), seasoning (15 g), flavor enhancer (5 g). Standard methodology and techniques were used to produce the sausage: a cutter was used first with chopped beef, chopped pork, MDPM, ice and additives. Later, chopped fat, seasonings and more ice were added. The mixture was then wrapped in a cellulose artificial casing prior to cooking, which was carried out in water hot enough to raise the sausage internal temperature to 72 C, and holding it at this temperature for around 2 h. After that, cold water was used to reduce the internal sausage temperature to 40 C; the sausage was then removed and superficially dried followed by removal of the casing, immersion in a aqueous hot bath with the colorant for 15 min at 70–75 C, weighing and storage at 5–7 C. The MDPM inclusion in the sausage occurred by replacing some of the meat mixture (beef + pork + pork fat) by an equal weight of MDPM. Different MDPM contents were tried (0%, 20%, 40%, 60%, 80% or 100% w/w MDPM). A 100% MDPM substituted sausage therefore means that all beef and pork from the original formulation was replaced by MDPM, whereas the other ingredients were kept constant. The MDPM, the beef and the pork were submitted to preliminary physical–chemical analysis of total carbohydrates, moisture, lipids and protein. All the analytical procedures were conducted according to the Brazilian standard procedure (Instituto Adolfo Lutz, 1985) and for each analysis, three measurements were carried out. The mean values are shown in Table 1. Tensile and compression tests were carried out on lab-made and commercial (standard) sausages, using a universal testing machine EMIC DL 10.000 at 20 C with a load cell of 100 N. Dumb-bell specimens were used for tensile and due to the natural fragility of the sausage, special semi-cylinder clamps with a rubber inner surface were designed and built. Due to the heterogeneity of the sausages, a aluminum mold was used for the cutting of the specimens so that their cross-section were made into a constant dumb-bell shape.

2. Materials and methods

Table 1 Typical composition of the meats used

The following ingredients were used for the laboratory made sausage: chicken MDPM, beef, pork, pork fat, ice, salt, cassava starch, sodium nitrate, stabilizer––sodium polyphosphate, antioxidant, seasoning,

Moisture (%) Ash (%) Lipids (%) Proteins (%)

MDPM

Pork

Beef

64.3 0.85 22.65 12.20

39.8 0.3 31.8 28.1

67.9 0.3 12.9 18.9

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Compression tests used two flat parallel square (200 mm · 200 mm) platforms and cylinder shaped, 25 mm high specimens cut from the original sausage were used. A minimum of 15 repetitions was used for each studied experimental condition and all sets of data were analyzed for statistical significance using a corrected analysis of variance, followed by independent t-tests (significant differences for p-values < 0.01) using commercial statistical software.

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Table 3 Variation in tensile strength as a function of the MDPM content for the lab-made sausage MDPM content (%)

Tensile strength (kPa)

Normalized strength (%)

0 20 40 60 80 100

39.3 36.5 35.5 33.6 23.5 13.7

100.0 92.7 90.3 85.4 59.7 34.8

(±6.5)a (±4.5)a (±4.6)ab (±2.9)b (±2.9)c (±3.1)d

a,b,c,d: different letters mean significant differences at 1% level.

3. Results and discussion Table 2 shows the effect of the variation of strain rate on the tensile strength for the commercial and the labmade sausage. Both types of sausage show the same tendency, namely, the higher the strain rate, the higher the tensile strength. However, this increase is more pronounced for low strain rates values and therefore a 50 mm/min strain rate value seems to be appropriate for testing since it is included in a safe range of strain rates (35–100 mm/min) which do not show statistically significant variation. This result is an indication that the discussion presented here for the lab-made sausage may be also applied to commercial sausage. It is important to bear in mind that although the values for both kinds of sausage are very close, this fact does not mean that the commercial sausage uses the same content of MDPM (0%, in this case), since the formulation and processing may be quite different. Table 3 shows the change in tensile strength of sausage containing 0%, 20%, 40%, 60%, 80% and 100% of MDPM. In this table, a normalized strength (ratio between tensile strength of MDPM-substituted sausage and tensile strength of 0% MDPM-substituted sausage) is used to further quantify the observed differences. Actually, the addition of MDPM is responsible for large changes in sausage resistance to tensile testing. With additions of up to 40% MDPM (35.5 kPa), the sausage is still able to keep its structural integrity at the same statistical level as the 0% substituted sausage (39.3 kPa). Further addition, however, starts to compromise the

sausage structure, with a 15% decrease in tensile strength (60% MDPM). Whilst sausage formulated with 60% MDPM may still be considered for use, the 80% and 100% MDPM content sausages are ruled out, since these last two were too weak to resist normal packaging and storage practices. Nevertheless, it is known that the addition of other ingredients that improve cohesiveness and therefore improve tensile strength may be used commercially. As can be seen in Table 4, the compression strength of the commercial sausage increased with increasing strain rate. For the same reasons mentioned above, a 50 mm/min strain rate was considered appropriate for sausage compression testing and it was used for the subsequent analysis. The effect of MDPM substitution on sausage compression strength (Table 5) was somehow similar to those for tensile strength, namely, for an addition of

Table 4 Compressive strength as a function of the strain rate used for testing the commercial sausage Strain rate (mm/min)

Commercial sausage

5 20 35 50 70 100

106.0 136.9 141.1 143.9 144.7 146.3

(±9.3)a (±26.1)b (±33.3)b (±23.2)b (±8.2)b (±12.0)b

a,b,c: different letters mean significant differences at 1% level.

Table 2 Tensile strength as a function of the strain rate used for testing the commercial sausage and the lab-made sausage (0% MDPM) Strain rate (mm/min)

Commercial sausagea

Lab-made sausagea

5 20 35 50 70 100

30.9 34.9 39.0 40.2 40.7 41.9

30.1 37.7 39.5 39.3 41.9 42.0

(±3.5)a (±7.1)b (±4.2)c (±5.6)c (±4.0)c (±4.5)c

(±2.5)a (±2.2)b (±1.8)b (±6.5)b (±6.6)b (±5.7)b

a,b,c,d: different letters mean significant differences at 1% level. a Independent statistical analysis for the two sets of data.

Table 5 Variation in compressive strength as a function of the MDPM content for the lab-made sausage MDPM content (%)

Compressive strength (kPa)

Normalized strength (%)

0 20 40 60 80 100

195.7 186.8 171.2 162.5 112.2 67.0

100.0 95.5 87.5 83.0 57.3 34.2

(±12.9)a (±13.5)a (±10.0)b (±15.1)b (±6.8)c (±6.3)d

a,b,c,d: different letters mean significant differences at 1% level.

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up to 20% MDPM the sausage still keeps its structural integrity at the same level as the non-substituted sausage. For the 40% and 60% MDPM-substituted sausage, 171.2 and 162.5 kPa, respectively, there is a statistically significant decrease in compressive strength. Further increase was responsible for an accentuated reduction of compression strength. In this case, however, the 60% MDPM-substituted sausage still has a compression strength just higher than that for the commercial sausage (143.9 kPa–50 mm/min data in Table 4) and therefore still has enough compressive structural integrity for commercialization. Comparison of normalized tensile and compressive strengths (Fig. 1) has shown that tensile and compression properties are affected in a similar way by the addition of MDPM. Moreover, MDPM substitution of more than 60% at sausage formulations severely degrades the measured mechanical properties. These findings corroborate the Brazilian legislation (Instruc¸a˜o Normativa, 2000), which limits the MDPM addition at 60% in the formulation of sausage. The lab-made sausage, with various MDPM contents, and the commercial sausage used for comparison were analyzed for moisture, ash, fiber, lipid, protein and carbohydrate content (Table 6) and these results, especially those for moisture, lipid and protein content,

can be associated with the findings regarding mechanical properties and the behavior shown in Fig. 1. Table 6 shows an increase in moisture content with MDPM content, a consequence of the higher ability of the MDPM to retain water when compared to meat (beef and pork). These results agree with the findings of Li, Carpenter, and Cheney (1998), who have found that hardness, springiness and cohesiveness decrease with increasing water content. Table 6 also shows a decrease in lipid content with MDPM content. This may be explained by the fact that less fat content compromises the emulsificating ability of the formulation, which ultimately causes a loss of cohesiveness, as discussed by Crehan et al. (2000). This is accurate up to a limit of about 35% since higher fat contents affect the stability of the emulsion (Reagan, Liou, Reynolds, & Carpenter, 1983). The decrease in the protein content is also a consequence of the inclusion of MDPM (Table 6). This occurs because the protein value of the MDPM is lower than that for the meat which has been substituted and therefore there is a decrease in the content of myofibrillar proteins, particularly myosin, which are responsible for the cohesiveness of cooked sausage. Ultimately, this decrease reduces the tensile and compression strength since this affects the emulsificating ability of the formulation (Farouk, Wieliczko, Lim, Turnwald, & Macdonal, 2002). As it has been reported by Li et al. (1998), the decrease in protein content ultimately affects mechanical properties, translated here as the tensile and compressive strength.

4. Conclusions

Fig. 1. Comparison of normalized tensile and compressive strength for the lab-made sausage.

This work confirms the existence of a strong correlation between the MDPM content of sausage and its resistance to tensile and compressive strength. Tensile strength varied from 39.3 to 13.7 kPa, whereas compressive strength varied from 195.7 to 67.0 kPa for 0% to 100% MDPM substituted sausage and therefore both properties decrease when the MDPM content is increased. MDPM content higher than 60% causes severe loss of tensile and compressive strength, showing values

Table 6 Physical–chemical analysis of sausage: the commercial one (comm.) and the lab-made sausage (from 0 to 100% MDPM content) Comm.

Moisture Lipids Proteins Carbohydrates Ash Fibers (·10)

54.23 20.5 14.9 6.21 4.05 1.20

Lab-made sausage (MDPM content) 0%

20%

40%

60%

80%

100%

59.86 19.89 15.89 2.37 1.83 1.60

63.98 16.89 14.42 2.82 1.79 1.00

65.89 12.34 14.89 4.93 1.77 1.80

68.99 11.82 13.01 4.88 1.17 1.30

69.07 12.05 11.52 6.09 1.16 1.10

69.81 11.20 10.58 7.14 1.17 1.00

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