ORIGINAL

Applying multicriteria analysis for choosing the best marination for pork

Aplicación de análisis multicriterio para elegir el mejor marinado para la carne de cerdo

Nieto VMOS,¹* M.Sc, Caldara FR,¹ Ph.D, Nääs IA,¹ Ph.D, Moi M,¹ M.Sc, Almeida Paz ICL,¹ Ph.D, Garcia RG,¹ Ph.D, Seno LO,¹ Ph.D, Santos LS,¹ M.Sc.

¹Federal University of Grande Dourados - UFGD, Agrarian Science College, Rodovia Dourados - Itahum, km 12, Caixa Postal 533 - CEP: 79.804-970, Dourados, MS, Brazil.

*Correspondencia: viviane.vmos@gmail.com

Received: February 2014; Accepted: September 2014.

Objective. This research aimed to choose a best marination solution using the Analytic Hierarchy Process (AHP). Materials and methods. Pork meat samples were collected in a commercial slaughterhouse, and they were randomly distributed in four treatments with three different salt contents blend. Color, pH, retention of the solution, exudate and cooking loss, shear force and sensory attributes were assessed and evaluated. Multicriteria analysis using AHP was applied to the results in order to choose the best overall marination solution. Criteria used for selection were the physical and sensory characteristics of meat, and based on these criteria were classified solutions marination. Results. Results showed that the combination of the salts was the best alternative (Na₂CO₃+NaCl+Na₅P₃O₁₀), followed by the solutions of (Na₂CO₃ + NaCl), and (Na₅P₃O₁₀ + NaCl). Conclusions. All tested solutions with the salts used alone or in combination led to better physical and sensory attributes than the meat not marinated.

Key words: Firmness, sodium chloride, sodium tripolyphosphate, texture (Source: CAB).

RESUMEN

Objetivo. Esta investigación tuvo como objetivo elegir la mejor solución para los productos marinados, utilizando el Proceso Analítico Jerárquico (AHP). Materiales y métodos. Las muestras de carne de cerdo fueron recogidas en un beneficiadero comercial, y fueron asignadas aleatoriamente a cuatro tratamientos con tres contenidos diferentes de soluciones salinas. Color, pH, solución de retención, pérdida de exudado, pérdida de peso por cocción, fuerza cortante y atributos sensoriales fueron analizados y evaluados. Fue utilizado el análisis multicriterio AHP jerárquico con el fin de elegir la mejor solución de marinado. Los criterios adoptados para la selección fueron las características físicas y sensoriales de la carne y con base a estos criterios se clasificaron las soluciones del marinación. Resultados. Los resultados mostraron que la mejor combinación de sales fue la alternativa (Na₂CO₃ + NaCl + Na₅P₃O₁₀), seguida por (Na₂CO₃ + NaCl + NaCl y Na₅P₃O₁₀). Conclusiones. Todas las soluciones ensayadas con sales usados sólos o en combinación dieron lugar a los mejores atributos físicos y sensoriales de que la carne sin marinar.

Palabras clave: Cloruro de sodio, firmeza, textura, tripolifosfato de sodio (Fuente: CAB).

Meat appearance is an essential aspect of consumers' acceptance and many factors affect this characteristic. Among them, it is the water-holding capacity, which is the ability that the muscle tissue has to retain water (1), when processes such as cutting, cooking and pressing are applied. Marination techniques contribute to improve the quality of the meat and add value to them. Marination involves the use of salts with or without the addition of condiments for promoting the increase of meat water retention, and leading the meat to better physical and sensory characteristics (2,3).

Alkaline salts such as polyphosphate and sodium bicarbonate are often used in marination solutions. They have the ability of increasing the meat Ph and water holding capacity to improve color stability, and to provide meat more flavor and juiciness (4,5). Sodium chloride acts in the extraction and solubilization of muscle proteins, contributing to the increased the water holding capacity, reduction of the cooking loss and improves the quality and texture of the product (6,7). Current literature shows the synergistic effect of the sodium polyphosphate, sodium bicarbonate and sodium chloride (4,8). Besides the benefits obtained on the physical properties of the meat, it can also be an effective strategy to reduce or eliminate peculiar aromas and flavors of pork. Since the meat quality is determined by a combination of factors the choice of marination solutions is clearly a multicriterial task which involves different aspects related to benefits for the processing industry and consumers, such as functional and sensory characteristics of the meat.

Multicriteria methods for decision making support aim to determine the relationship of preferences among alternatives which are being evaluated for a certain purpose (9,10). Amongst the possible mathematical solutions, the use of the Analytic Hierarchy Process (AHP) allows the option to manage the selected criteria within a level structure, considering of viable alternatives. It is also possible to classify them according to known parameters. The AHP has been applied in various scenarios where there are alternatives and the range of possible solutions can be arranged in a matrix (11-13). This approach allows combining quantitative and qualitative factors for decision making and allows the input of information from other research database (14).

The objective of this study was to choose the best marination blend for pork using the Analytic Hierarchy Process (AHP).

MATERIAL AND METHODS

Sample collection. Meat samples (Longissimus' dorsi muscle) were obtained from 115 kg male swine from the same genetic strain, which were subjected to the same pre-slaughter and slaughter handling, at a large commercial slaughterhouse (2300 heads/day) after 24 h of carcass chilling. Samples were adequately transported to the Federal University of Grande Dourados (UFGD) at Dourados, MS, Brazil where the remainder of the study was carried out.

Treatments and experimental design. The samples (n=40) were distributed in a randomized design, in four treatments: C, control without marination; M1, sodium bicarbonate (Na₂CO₃) and sodium chloride (NaCl) solution; M2, sodium tripolyphosphate (Na₅P₃O₁₀) and sodium chloride (NaCl) solution, and M3, sodium bicarbonate (Na₂CO₃), sodium tripolyphosphate (Na₅P₃O₁₀) and sodium chloride (NaCl) solution. Ten replicates per treatment were used. The solutions were prepared in order to achieve 9.09% of the salt solution on the final product considering the injection of the approximately 10% of the sample weight (Table 1).

Process of marination. The marination process took place at a controlled environment with ambient temperature at 13°C. Samples were weighed and then the solution was injected uniformly throughout of the sample using manual injector with a needle. After the injection of the salt solutions, the samples were weighed, individually packed in plastic bags, and stored under refrigeration at 4°C for 24 h to equilibrate the solutions. Samples were removed from storage and reweighed to determine purge loss.

Physical and sensorial analysis. For determining the weight loss by cooking, the samples were baked in an electric oven at 300°C for 16 minutes, eight minutes on each side, reaching an internal temperature of 80°C, and checked using a calibrated hand held digital thermometer. After baking were cooled to room temperature for one hour and the surface moisture removal with absorbent paper, and reweighed. The percentage weight loss by cooking was determined by the difference between the initial weight and final weight. The samples were evaluated for staining before and after marination, for being so exposed to air for 30 minutes, oxygenation of the same order. To determine the shear force, was used the samples prepared as described under weight loss by cooking, of which six were removed cylinders 13 mm in diameter in the direction parallel to the muscular fibers with the aid of a punch. The shear force of the meat was measured using a texturometer (TA.XT2i, Stable Micro Systems), with a Warner-Bratzler blade. The shear force was determined directly from the force curves as a function of deformation, with the use of the “Texture Expert” V.1.15 (SMS) and calculated as the average of the measurements, is expressed in kgf.

The objective evaluation of color was carried out with the Minolta spectrocolorimeter surface (model Minolta® CR 410, SCI setting, D65 illuminant and 10° viewing angle) using the scale L* (brightness), a* (redness) and b* (level of yellowness) CIELab system. The measurements were performed at three different points on the sample surface, taking the average as the value determined. The sensory evaluations were performed using a panel of seven trained panelists who evaluated the samples for tenderness, flavor and juiciness based on a scale of nine points (1=extremely dry, tough or intensely off-flavored; and (9=extremely moist, tender or no off-flavor), and using the methodology adopted by Santos (8).

Data were analyzed using Tukey test and Kruskal Wallis test at 95% significance and processed using the software SAS 9.2 (2000) applying the GLM (General Linear Model) procedure.

Analytic Hierarchy Process. The analytic hierarchy process (AHP) involved four stages: (A) Structuring the selection of the appropriate marination solution: identifying and structuring the objective of selecting the proper marination solution required careful literature review which provided the basis for quantitative modeling. The challenge consisted in identifying the attributes considered relevant by the pork processing industry and consumers. The objective hierarchies were built attending this classification (15). In order to establish the hierarchy the attributes were selected by three experts in this field of knowledge, and they were based on the quality criteria which were considered valuable by the meat industry and consumers. (B) Identification of alternative options: The marination alternatives were initially selected based on current literature (3-5). (C) Identifying the applied selection criteria: The selection of the criteria was based on the results of the present experiment and additional information was chosen based also on current literature (4,3,16). The scheme of the AHP system was designed using three distinct levels (Figure 1). (D) Developing the weighting scheme and ranking the options: The purpose of the AHP is to provide a vector of weights expressing the relative importance of those layout alternatives for each chosen criterion.

The scale of importance was defined according to the methodology adopted by Caldara et al (13) using the 1-9 scale for pairwise comparison (Table 2).

A pairwise comparison matrix is formed in the application of the AHP system, in which rows and columns are assigned to the components belonging to the same related component in the decision hierarchy. The weight of component i compared to component j with regard to the corresponding component is determined using scale (Table 2) and assigned to the (i, j) th position of the pairwise comparison matrix (9), chosen to support comparisons within a limited range, but with sufficient sensitivity. The reciprocal of the assigned number is assigned to the (j, i) th position. Once the pairwise comparison matrix is formed, weights of components are calculated by solving for the eigenvector of the pairwise comparison matrix.

The consistency is obtained by setting (n_ji= 1/n_ij). Therefore, the comparison needs to be repeated for each column of the matrix, i.e. independent judgments must be made over each pair. The matrix is consistent if and only if (λ_max = n). Considering that the inequality (λ_max > n) always exists, the average of the remaining eigenvalues can be used as a “consistency index” (CI= (λ_max - n)/(n - 1)), which is the difference between (λ_max) and n divided by the normalizing factor (n - 1). The consistency index of the selection of the best marination process was compared with the average random consistency index (RI) which was obtained from associated random matrices of order n to compute the error due to inconsistency (9). A consistency ratio (CR= CI/RI) correlating the consistency index and a random consistency index (RI) value lower than 10% was adopted, in order to maintain the matrix consistent. The important component of this decision theory is the preference that is associated with a utility function. In this decision making process, both preferences and uncertainty were merged into a unified and analytical framework, which were related to the data from the experimental procedure.

The results statistical levels of significance were used as reference for applying in the pairwise comparisons for the criteria shown in figure 1 and the choice of alternatives. Computational calculations and analysis was done using the web based software (15).

RESULTS

The weight is referred to the importance an explicit factor was considered by the experts and results from the experiment. Global weights confirm that physical characteristics were more significant (75.0%) in selecting the best marination then sensorial characteristics (25%) as seen in figure 2A.

Within the sub-criteria for each characteristic those, which were determinant in the final results, were the exudates loss (27.3%) followed by the cooking loss (18.1%) and the salt solution retention (13.9%).

The best marination was found as the solution that mix up the three salts Na₂CO₃+NaCl+Na₅P₃O₁₀ (43.3%), followed by Na₂CO₃+NaCl (25%), and Na₅P₃O₁₀+NaCl (21.8). The control was the worst result (9.9%) as shown in figure 2B. The physical characteristics (pH, retention of the solution, weight loss, cooking weight loss and shear force) were the most significant criteria in the second level (74.9%).

Although the sensory attributes presented lower weight in deciding the best solution of the marination, it was observed that these attributes were somewhat higher in the marinated meat (>23%) compared to control, whose participation was only 16%. This was expected since the samples of the control treatment received no injection solution, while the others were injected with solutions containing ingredients considered flavors.

Comparing the samples without the marinated meat marinated meat samples, it was observed that the characteristics were improved by the application of treatments figure 3, A-D.

Compared with the control, the marination solutions M1, M2, M3 shown to be effective in improving the physical characteristics and the color characteristics of pork.

DISCUSSION

The marination of the meat with alkaline solutions, obtained by means of phosphate and sodium bicarbonate, reduces the loss of the water content by increasing the water binding and retention of the natural juice (8,17).

The reduction in the cooking loss may be partly explained by water-protein chemical interaction that occurring in the marination process. This interaction is due to the attraction of the charges, which are affected by the pH of the brine. During the meat cooking process it occurred the fixing of water through of the solidification of the gel protein where the water content and absorbed are retained. The salts and phosphates used in marination act on the muscle fiber de-polymerized the myosin filaments and facilitating the segregation of the complex act-myosin, increasing the dissolved protein (17,18). Moreover, sequester the metal ions negatively charged, leaving the positive charges available for binding the water molecule, thereby promoting the increased of the capacity of the meat to retain water (7,17,18). The marination with a solution of the sodium chloride and tripolyphosphate improves the texture of the fibers of the meat, making it the softest (5). In general, the most obvious mechanisms in reducing of the shear force after application of holding capacity, improving the tenderness and texture of the meat (7, 21). This effect enhances the meat characteristics promoted by the action of sodium chloride was also observed by the authors (22) when working with acid solution. The weakening of the myofibril by the action of sodium bicarbonate is not well understood although, it is clear that the reduction in shear force has been similar to that achieved with sodium chloride and phosphate. Since the water-holding capacity directly influences the sensory characteristics of the meat, the flavor, juiciness and tenderness were significantly improved with the marination process (8). The softness can be attributed to a combination of the higher water content and the muscle structure weakened by the action of the salts. The juiciness of the marinated pork loins can be explained partly due to the reduction of and cooking loss, promoted by alkaline salt solution. When the alkaline salts were used alone M1 and M2 it showed a similar effect on the improvement of most characteristics evaluated, except that of the solution M1, which promoted the less shear force of the meat, while the solution M2 provided better tenderness, as evaluated by the panel sensory figure 3B. As it was assigned higher weights to the physical than to the sensorial characteristics, the solution M1 can be considered better figure 2.

With the exception of pH, retention of the solution and color (L*, a*, b*), all parameters were improved by the association of the salts M3 when compared to their use individually figures 3C and 3D. It was proven in this way, positive synergy effect between the salts, greatly improving the quality characteristics of pork, supported by studies of (4).

The multicriterial analysis using AHP provided a comprehensive view of the results that were found statistically in a compartmentalized manner. When the criterion were separately analyzed, it becomes more difficult to decide on the best alternative, whether the results are somewhat different among the different criterion. Thus, with assigned weights according to their relative importance, in view of the processing industries and consumers, it was possible to determine in a global context which was the best amongst the tested alternatives.

In conclusions the multicriteria analysis was able to reveal the most suitable choice for the marination of the pork, given all the criteria involved in the selection process. The analysis indicates that use of the alkaline salts in combination is the best way to improve the physical and sensory characteristics of the meat.

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