EFFECTS OF REDUCING SALT LEVELS ON SOME QUALITY CHARACTERISTICS OF TURKEY MEATBALL

Meltem Serdaroğlu¹, Gulen Yıldız-Turp¹, Haluk Ergezer^2
1 Ege University, Engineering Faculty, Food Engineering Department, Izmir, Turkey
² Food Engineering Department, Ege University, Bornova, Turkey

ABSTRACT

In the modern meat industry, salt is used as a flavouring or flavour enhancer and is also responsible for the desired textural properties of processed meats. The ultimate goal of ingredient suppliers and meat processors is to produce reduced sodium meat products that consumers can enjoy. In this research, the effects of four levels of salt (0,1.5, 2, 2.5%) on some quality characteristics of turkey meatballs were investigated during the storage at 4°C, for 7 days. Meatballs were prepared with equal amounts of turkey breast and thigh. Salt resulted lower higher cooking yields at each added level and also improved moisture retention. Higher salt levels significantly increased TBA levels during storage. Sensory panel results indicated that, salt levels affected quality characteristics of turkey meatball during storage. According to sensory panel scores, salt level can be reduced. However reducing salt level in meatball formulation, increased L* value.

Key words: salt, turkey meatball, sensory evaluation, oxidation.

INTRODUCTION

Salt has been used since ancient times for the preservation of meat products and is one of the most commonly used ingredients in processed meat products. In the modern meat industry salt is used as a flavouring or flavour enhancer and is also responsible for the desired textural properties of processed meats [4]. Salt also imparts a number of functional properties in meat products; it activates proteins to increase hydration and water-binding capacity, increases the binding properties of proteins to improve texture, increases the viscosity of meat batters, facilitating the incorporation of fat to form stable batters and essential for flavor and bacteriostatic effect [22].

Most processed meat products contain variable amounts of salt and are associated with high salt contents. Based on the scientific information, meat industry and consumers have become more aware of the relationship between sodium and hypertension, therefore in many countries, the demand for a variety of low salt meat products has increased. The main source of sodium in diet is sodium chloride. On a population basis, it has been established that the consumption of more than 6 g NaCl a day is associated with an age-increase in blood pressure. Therefore, it has been recommended that the total amount of dietary salt will be maintained at about 5-6 g/day [1, 5]. It is, however, recognized that genetically salt susceptible individuals and hypertensive will particularly benefit from low-sodium diets, the salt content of which should range between 1 and 3 g a day [14].

Developing low salt meat product is however, not straightforward. A particular problem with low salt meat products is that only the perceived saltiness, but also the intensity of the characteristic flavor decreases, when salt is reduced [13]. Solubilization of muscle proteins in salt solutions is an important physicochemical process in the manufacture of processed meats, in which solubilization normally occurs as a result of comminuting and blending of meat in the presence of salt [23]. Reduction in meat products thus has adverse effects on water and fat binding, impairing overall texture and increasing cooking loss, and also sensory quality Potential sodium chloride reduction depends on aspects connected with the type of product, its composition, the type of processing required and preparation conditions. These factors determine the type of product that can be modified and the technological limitations of salt reduction. [14]. The aim of this study was to evaluate the effects of NaCl level on some properties of turkey meatball during storage at 4°C for 7 days.

MATERIALS AND METHODS

Turkey meat from a local processing plant with a proximate composition of 74% moisture, 23.3% protein, 2.23% fat and 1.9% ash was used for the meatball production. Hand deboned turkey meat was trimmed of all visible fat and connective tissue. Equal amounts of breast and thigh muscles were ground through a 3 mm plate mixed with black pepper (0.2%) curry (0.5%) and different amounts of salt [1.5% (S1.5), 2% (S2) and 2.5% (S2.5)]. Control group (C) with no added salt was also prepared. Meatballs were formed and then stored at 4°C for 7 days in polypropylene boxes with lids.

Percent cooking yield was determined by calculating weight differences for samples before and after cooking [11].The moisture retention value was determined according to an equation by El- Magoli et al. [6]. TBA analyses were done on meatballs, according to Tarladgis et al. [21] and CIE color parameters (L*, a*, b*) of raw patties were measured by using ColorFlex HUNTERLAB-USA were performed on 0, 5^th and 7^th days of storage.

Meatballs were served warm to a 8 membered trained panel (graduate students and staff of Ege University Food Engineering Department) for sensory attributes of appearance, colour, juiciness, hardness, flavour and overall acceptability on 0th, 5th and 7th days of storage. Samples were cooked in a Teflon coated pan, for 5 min at each side before serving to the panel. Colour was evaluated using a five point scale (5: extremely intense 1: extremely poor) for other investigated parameters an eight point scale was used where, 8 = extremely desirable, juicy, tender, intense in beef flavour, acceptable and 1 = denoted extremely undesirable, extremely dry, tough, devoid of beef flavour, unacceptable. Water and bread served for cleaning the mouth between samples.

All analyses were performed in duplicate with the entire experiment replicated twice. The data was analyzed by one way ANOVA using the SPSS software version [19]. Differences among the means were compared using Duncan’s Multiple Range test. A significance level of P≤0.05 was used for all mean evaluations.

RESULTS AND DISCUSSION

Table 1 represents the cooking yield and moisture retention values of meatball samples. Control samples with no added salt had lower cooking yield than other sample groups. Increasing the salt level in meatball formulation had no effect on cooking yields of samples. One of the functions of NaCl in meat products is to extract myofibrillar proteins which contributes to meat particle binding, fat emulsification, water-holding capacity and thus reduces cook losses [18]. Hsu and Sun [9] found that cooking yields of the Kung-wans increased at higher salt levels. Ruusunen et al. [14], investigated the effects of various NaCl levels on the quality of ground patties and they indicated that increased sodium content gave the lower cooking loss.

Control samples had significantly lower moisture retention from the S2 and S2.5 samples (P<0.05). The highest moisture retention value was detected in S2 samples but above 2% salt level, a little decrease was observed. According to these results, salt should be used at 2% level for effective moisture retention in turkey meatballs. Ayo et al. [2] determined that weight loss less than 4% in meat batters containing 2.5% NaCl, indicating good water and fat binding properties.

Changes in the colour values (L*, a*, b*) of meatballs during the storage are are shownş in Fig. 1, 2 and 3. Reducing the salt levels in meatball formulation significantly increased L* values even at the beginning of the storage period (P<0.05). Increasing the salt levels in meatballs significantly effect lightness even at the beginning of the storage period (P<0.05). Salt caused a dark colour in turkey meatballs. Similarly, Kong et al. [10], observed that brightness of the beef surimi decreased with the amount of NaCl increased. Hsu and Sun [9] reported that salt level had no effect on the colour of emulsified meatballs.

Redness (a*) and yellowness (b*) of samples were not significantly affected by different levels of salt (P>0.05). a* and b* values of samples were not significantly affected by different levels of salt (P>0.05). Similar to our results, Hsu and Chung [8], noted that a* and b* values of emulsified meatballs were not significantly affected by the salt content however, its lightness, as measured by the L* value was changed significantly. Schwartz and Mandigo [17], reported that salt improved cooked colour of meatballs.

At the beginning of the storage period, salt added groups showed higher a* values, however, on 7^th day of storage a* values decreased as the salt level increased in the formulation. Similar to our results Tan and Shelef [20] stated that the red meat color (a* values) was enhanced immediately after the addition of NaCl, but declined rapidly at 2°C and the values on day 8 were 30 – 50% lower than those on day first. On zero day of storage control samples and samples added with 1.5% salt were more yellow than S2 and S2.5 samples. No differences were found between the samples on other investigated periods.

TBA values of samples were significantly affected by the salt level (P<0.05) and the storage period (P<0.05). TBA values increased in all groups during the storage period (Fig. 4). The initial TBA values of meatballs ranged from 0.51 to 0.7 mg malonaldehyde·kg^-1 and the final TBA at the end of the storage period ranged from 0.7 to 0.95 mg malonaldehyde·kg^-1 sample.

All meatball samples had TBA values within the acceptable limits (<1.0) concerning oxidative rancidity. The explanation for this fact is an efficient antioxidant activity of the curry and blackpepper. Biswas et al. [3] found that curry leaf powder effectively inhibited lipid oxidation in chicken patties during refrigerated storage. Salt is a powerful prooxidant in muscle foods O’Neill et al. [12]. On 0^th, 2^nd and 5^th, days of storage, TBA values of S2.5 samples that contain highest amount of salt (2.5%) were significantly higher than the other samples. Schwartz and Mandigo [17] studied several combinations of 0–2.5% NaCl and 0–0.5% sodium tripolyphosphate in restructured pork and found that salt increased TBA values. Similarly O’Neill et al. [12] found that, salt accelerated lipid and cholesterol oxidation in chicken patties following cooking and refrigerated storage. Sarraga et al. [16] showed that high salt concentration led to lower TBA values of raw and dry cured porcine loins.

Fat and salt jointly contribute to many of the sensory properties in processed meats. On zero day flavor and overall acceptability scores were higher on salt added samples than control samples, no differences were found on other investigated sensory properties (Table 2). Besides the salty taste NaCl also introduces the characteristic taste of meat products (= flavour enhancer). Thus, salt reduction does not reduce only the perceived saltiness but also weakens the overall flavour in meat products [14]. Sodium chloride is a flavour enhancer, increasing the characteristic flavour of meat products. Both the perceived saltiness and the flavour intensity depend on salt content in meat products [15]. On 5th day no other parameters affected except juiciness and flavour by salt addition (Table 3). Control samples with no salt had lowest juiciness and flavour scores. However all investigated parameters except colour affected by salt addition on day 7 (Table 4). It is appeared that addition levels of salt at around 1.5% resulted more acceptable product. Hsu and Chung [7] found emulsified meatballs added with 2.7% salt were more acceptable.

CONCLUSIONS

Most sodium chloride in the diet comes from processed foods. Reduction of sodium chloride depends on some factors such as type of the product, composition, the type of processing and preparation conditions. Meatballs prepared with no salt had lower cooking yields, and lowest flavour and juiciness scores. Higher salt levels significantly increased TBA levels during storage of turkey meatballs. Turkey meatballs prepared with 1.5% NaCl were salt acceptable.

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Accepted for print: 4.06.2008

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