Phosphate Reduction in Emulsi fi ed Meat Products : Impact of Phosphate Type and Dosage on Quality Characteristics

Phosphates occur naturally in the form of organic esters in many kinds of food, including meat. These phosphate esters are organically bound and only partially absorbed in the gastrointestinal tract. Phosphates are important for human health since they are responsible for growth, maintenance and repair of tissues and cells of living organisms. However, an avoidable risk to health arises from the increased use of phosphates as food additives and preservatives. These ‘free’ (not organically bound) phosphates are eff ectively absorbed in the gastrointestinal tract. An association was found between high intake of phosphate additives and cardiovascular morbidity and mortality (1). This was already recognized in chronic kidney disease patients but questions arise with regard to the general population (1,2).


Introduction
Phosphates occur naturally in the form of organic esters in many kinds of food, including meat.These phosphate esters are organically bound and only partially absorbed in the gastrointestinal tract.Phosphates are important for human health since they are responsible for growth, maintenance and repair of tissues and cells of living organisms.However, an avoidable risk to health arises from the increased use of phosphates as food additives and preservatives.These 'free' (not organically bound) phosphates are eff ectively absorbed in the gastrointestinal tract.An association was found between high intake of phosphate additives and cardiovascular morbidity and mortality (1).This was already recognized in chronic kidney disease patients but questions arise with regard to the general population (1,2).
The chemical formula, pH, solubility, E number and relative content of P 2 O 5 (in %) of several phosphate types have recently been presented (2).Phosphates fulfi l diff erent functional properties in meat products and can have an impact on pH, chelation, ionic strength and antibacterial activity (2,3,5,6).Monophosphates have a good buffering capacity but have no eff ect on muscle proteins (2).Diphosphates (especially TSPP) have the ability to dissociate the actomyosin complex of meat immediately, and tri-and polyphosphates help to activate meat proteins by partially chelating protein-bound Mg 2+ and Ca 2+ , both leading to increased solubilization of myosin and actin and depolymerization of thick and thin fi laments (7).As such, these proteins can maximally exert their emulsifying and gelling properties, which are very important with regard to the fat and water stabilization (8,9).However, due to their low solubility, di-and triphosphates cannot be used in brine.In this case more soluble, long-chain polyphosphates (such as SHMP) are applied, e.g. in the preparation of whole muscle meat products such as cooked ham.In addition, the buff ering capacity of some phosphate types can contribute to their functionality in meat.Water holding capacity (WHC) is greatly aff ected by pH, and is at its minimum at the isoelectric point (pI).The pI of meat proteins is in the pH range ±5.5, which is also the meat pH aft er rigor mortis.Increasing pH away from the pI will result in increased WHC.Addition of alkaline phosphates (e.g.TSPP and STPP) during the manufacturing of meat products will increase the pH in the slightly acidic meat.This increase in the pH will result in electrostatic repulsion between or within the meat proteins, resulting in higher WHC.Apart from the pH eff ect, WHC can also be increased due to a change in ionic strength.Phosphates aff ect ionic strength by forming polyelectrolytes in water, causing electrostatic repulsion between the meat proteins, which allows more space for binding water and hence, increased WHC.This is especially true for polyphosphates (e.g.SHMP).This also supports immobilization of water and the emulsifi cation of fat (3).Phosphates are not considered as direct preservatives but have a slight bacteriostatic eff ect and they also have an antioxidant eff ect (2,3,(10)(11)(12).
NaCl has a positive eff ect on the water binding of myofi brillar proteins (13), as it is able to increase myofibrillar protein solubility.A minimum concentration of 0.6 M is required to extract myofi brillar proteins out of the myofi bril, but lower NaCl concentrations are needed when SAPP or STPP are added to achieve a similar extraction eff ect (14,15).
In the last 20 years, many phosphate types and their mixtures (blends) have been studied in meat and meat products (2).Four diff erent phosphate types, mainly TSPP, STPP, SHMP and SAPP, are typically discussed.Globally, most studies used only one phosphate type (16)(17)(18)(19)(20). Studies that compared two or more phosphate types are outnumbered (21)(22)(23)(24).Moreover, the eff ect of phosphate type and/or blends was mainly tested on sensorial or physicochemical properties such as colour and pH (23)(24).The eff ect of phosphate type on quality characteristics such as texture and cooking loss remained limited to studies concerning restructured pork (25), buff alo meat and patt ies (21), beef (22) and goat meat and restructured goat meat products (26) while, to the best of our knowledge, no studies have been conducted concerning the use of diff erent phosphate types in cooked pork sausages.
Studies about diff erent phosphate levels, whether or not in combination with other substances (such as carrageenan or gum) in meat and meat products have also been discussed (2).The eff ect of phosphate reduction in meat or meat products was already evaluated in terms of phosphate diff usion, colour development, sensory att ributes and cooking yield (27,28).Studies about the eff ect of diff erent phosphate levels without other additives on quality characteristics are limited to smoked ham (29), beef meat (22,23) and red meat (17).Only one study has been found that evaluates the eff ect of meat and phosphate level on WHC and texture of emulsion-type pork sausages during storage (30).The combined eff ects of NaCl and raw meat pH on WHC in cooked pork/beef sausages with or without added phosphate were studied (31).However, the authors did not gradually lower the amount of phosphate to study the eff ect of phosphate content.
Therefore, the aim of this study is to reduce the amount of phosphate in emulsifi ed meat products and still maintain a high-quality product.Phosphate reduction is of import ant industrial relevance in the manufacturing of emulsifi ed meat products because it may give rise to a healthier meat product.First, the eff ect of seven diff erent phosphate types was tested on the physicochemical (colour and pH) and quality characteristics (structural and textural properties, emulsion stability and cooking loss), so that the most promising phosphate type could be selected for further cooked sausage manufacturing.Next, the amount of phosphate was reduced (5 diff erent mass fractions) and physicochemical and quality characteristics were again evaluated.Importantly, throughout the study att ention was given to the eff ect of phosphate on the rheological properties of the meat batt er, which has not been studied before in literature.This technique allows increased insight into the mechanism of action of the diff erent phosphates.

Manufacturing of cooked sausage
Cooked sausages were prepared in the pilot plant of the research group Technology and Quality of Animal Products (KU Leuven Technology Campus Gent, Gent, Belgium).Pork shoulder and pork backfat were obtained from a local industrial slaughterhouse (De Lausnay Rene BVBA, Destelbergen, Belgium).Raw materials were chopped, homogenized to generate one batch, vacuum-packed and stored at -18 °C until preparation (within a three-month period).All food additives were bought from Solina Group (Eke-Nazareth, Belgium).Cooked sausages were produced with (in g per 100 g): pork shoulder 40, pork backfat 35 and ice 25, together with nitrite curing salt 1.8, phosphate (see Table 1), sugar 0.5, white pepper 0.2, foil 0.05, ascorbic acid 0.05, glutamate 0.05, coriander 0.025 and cardamom 0.025.All ingredients were calculated in relation to the total mass of raw materials (pork shoulder and pork backfat) and ice.
First, the raw meat (pork shoulder) was chopped together with the ice, salt and phosphate in a bowl cutt er (model UM12; Stephan Machinery GmbH, Hameln, Germany) for 7.5 min.Next, the pork backfat was added to the meat batt er in the cutt er together with the remaining food additives.The total mass was cut under vacuum for 3 min to obtain a homogenous batt er.Temperature did not exceed 14 °C during processing to avoid protein denaturation and fat coalescence.Part of the batt er was immediately analyzed for emulsion stability and structural properties.In order to standardize the production and cooking process, the remainder of the batt er was fi lled into cans of standardized dimensions (d=7 cm, h=5 cm, m~250 g; Crown Verpakking Belgie NV, Hoboken, Belgium) rather than casings, cooked at 76 °C (core temperature 72 °C) in a cooking chamber (Rational Climaplus Combi ® CPC 61; Claes Machines, Paal, Belgium) and finally cooled to 4 °C.The resulting meat products, cooked in cans, served as a model product for cooked sausage.Therefore, throughout the text these products are referred to as cooked sausages.One week aft er the manufacturing, pH, colour, cooking loss and textural properties of cooked sausages were analyzed.
During the fi rst part of our research, seven diff erent phosphate types were tested.Each sausage formulation contained 0.17 % P 2 O 5, which is a standard amount used in the meat industry for emulsifi ed meat products.The mass fraction of P 2 O 5 in each phosphate diff ers (Table 1, second column), which resulted in a diff erent dosage (Table 1, third column).A product without phosphate was also processed and used as non-phosphate control product.
Aft er evaluating the quality characteristics of the cooked sausages prepared with diff erent phosphate types (Table 1), the phosphate type that contributed most to the quali-ty characteristics of the cooked sausage was used in the second part of our research, in which the mass fraction of P 2 O 5 was reduced from 0.17 to respectively 0.11, 0.06, 0.03 and 0.01 %.The product without phosphate prepared during the fi rst part was also used as control.Cooked sausages were prepared in triplicate per recipe.

Dynamic viscoelastic properties
Rheological measurements of sausage batt ers were performed using an AR2000ex controlled-stress rheometer (TA Instruments, New Castle, DE, USA) equipped with a 40-mm parallel plate system.A crosshatched upper and lower plate were used to prevent slippage of the sample.The gap was set at 1000 μm.The AR2000ex was supplemented with an effi cient Peltier temperature control system and upper heated plate (TA Instruments) to control the sample temperatures accurately.
Oscillation experiments were conducted at 13 °C.A 5-minute delay was set aft er transferring the samples to the rheometer, allowing the stress induced in the sample during sample loading to relax.Excess material was wiped off with a spatula before analysis.
Stress sweeps between 0.1 and 1000 Pa at a fi xed frequency of 1 Hz were performed to determine the linear viscoelastic region (LVR).The 'storage' and 'loss' moduli (G', a measure of elastic property and G", a measure of viscous property, respectively) and the 'phase angle' (δ) were directly obtained from the soft ware (32).The δ=90° represents a fully viscous material, while a fully elastic material is characterized by δ=0° (33).The complex modulus (G*), the ratio of the total tension to the deformation, was calculated as follows: /1/ G* represents the material overall rigidity or resistance to deformation.The stress range over which both G' and G" are independent of the applied stress amplitude is called LVR.Within this region, the structure is intact.The LVR was calculated from the stress sweep curves as the stress level at which G* deviates more than 5 % from a constant G* (plateau) value.More than 5 % deviation implicates an irreversible structure breakdown.

Emulsion stability
Emulsion stability was determined according to Hughes et al. (34).Raw sausage batt er (30 g) was placed in a pre-weighed centrifuge tube (VWR International, Leuven, Belgium) and the initial mass of the sample was registered.The sample was heated in a cooking chamber (30 min, 70 °C) and centrifuged (4230×g, 3 min, 25 °C, model 320R; Hett ich Universal, Newport Pagnell, UK).The drip loss (supernatant containing a mixture of water and fat) was weighed (aluminium weighing dishes; VWR International).The percentage of total expressible fl uid (TEF/%) was calculated by the following equation:

Cooking loss
One week aft er processing, cooking loss (CL/%) was calculated by determining the initial sausage mass and

Colour and pH measurements
The instrumental colour analysis was based on the 3-dimensional CIELAB colour scale.Aft er a week of cold storage, the colour of the freshly broached cooked sausages was measured by a portable refl ectance colourimeter Miniscan EZ 4500L 45°/0° (Hunterlab, Murnau, Germany) with 8-mm viewing area size.Illuminant D65 and a 10° standard observer were used to register the L* (lightness), a* (redness), and b* (yellowness) values, with one channel for L*, ranging from black (L*=0) to white (L*= 100), and two channels for a*, ranging from red (+a*) to green (-a*), and b*, ranging from yellow (+b*) to blue (-b*).
The pH value was measured with a portable meat pH meter (model HI 99163; HANNA, Nieuwegein, the Netherlands) inserted into the cooked sausage.

Texture
Hardness of the cooked sausages was evaluated using a Lloyd texture analyser (model TA Plus; Lloyd Instruments, Bognor Regis, UK).Cans with cooked sausage were axially penetrated to a depth of 2 cm using a load cell of 100 N and a cylindrical probe (d=6 mm; Lloyd Instruments) at a speed of 100 mm/min.Hardness was directly obtained from the recorded force-distance curves and described as the maximum force (N) to penetrate the sample.

Statistical analysis
All analyses were performed in triplicate on each sausage sample.Results are expressed as mean value±stan-dard deviation.Statistical analysis was performed using IBM SPSS Statistics v. 22 (35).All results were evaluated by one-way ANOVA.A Tukey's post hoc test was performed and a signifi cance level of p<0.05 was used to identify signifi cant diff erences.

Structural properties of cooked sausages infl uenced by phosphate type
The structural properties of all meat batt ers were rheologically analysed.As already mentioned in section Dynamic viscoelastic properties, δ=90° represents a fully viscous material, while a fully elastic material is characterized by δ=0°.The linear viscoelastic region (LVR) refl ects the stress range in which the structure of the sample remains intact.However, when the applied deformation increases, irreversible structure breakdown occurs.High G* values indicate a high resistance to deformation and a system having 'more' structure.2 indicate that the LVR of the sausage batt er was the highest in the control or SHMP samples.When no phosphate was added (control), the actomyosin complex was still intact and more capable of resisting external deformation.SHMP, a long chain polyphosphate, is mostly used in phosphate blends because of its high solubility, but it has no ability to dissociate the actomyosin complex and therefore, the actomyosin complex is also still intact.It is suggested that the high LVR in these samples refl ects an intact actomyosin complex due to which it can withhold higher stress before structure deformation occurs (36).When using monophosphates (MSP, DSP and TSP), the LVR decreased slightly compared to the control or SHMP preparation.Preparations without phosphate or with MSP, DSP and TSP had the lowest δ values and refl ect a more 'solid-like' behaviour.When monophosphates MSP, DSP and TSP were added, G* was signifi cantly (p<0.05)higher than with the other phosphate types, refl ecting 'more' structure and higher resistance to deformation.In contrast, the LVR was the lowest when TSPP, SAPP and STPP were added.It can be suggested that because TSPP, SAPP and STPP do have the ability to split the actomyosin complex, the sausage batt er was more sensitive to external deformation.This is also translated in the G* and δ values.Signifi cantly (p<0.05)lower G* and higher δ values when using TSPP, SAPP and STPP were observed, refl ecting 'less' structure, lower resistance to deformation and a more 'liquid-like' behaviour.These effects were more pronounced in case of TSPP and STPP than of SAPP.

Data in Table
In a recent study, the addition of salt to a liver batt er signifi cantly decreased the LVR (36).The authors concluded that NaCl dissolved the myofi brillar proteins and changed their original structure, leading to a more viscous-like and sensitive structure.The results could be more or less compared, keeping in mind that NaCl also aff ects protein functionalities like solubility, extractability, emulsifying and gelation properties (13).Apart from the former study, no comparison with literature could be made concerning the eff ect of phosphate type on structural properties of sausage batt ers or related products.
The loss of structure of the sausage batt er due to breakdown of the actomyosin complex is interesting because it indicates that myosin is released from the actomyosin complex and presumably can act as a natural emulsifi er and participate in the gelation process, which is crucial for the stabilization of fat and water in emulsifi ed meat products.In this respect, rheological analysis of the meat batt er provides an interesting tool in understanding how the sausage batt er is infl uenced by its composition and processing.

Eff ect of phosphate type on the pH of cooked sausages
Data in Table 2 also show that phosphate type had a signifi cant (p<0.05)eff ect on pH value.Preparations with TSP had the highest pH value, while the addition of SAPP resulted in the lowest pH value.The pH increased by 1.41 units and decreased by 0.31 units when using TSP and SAPP respectively, compared to the preparation without phosphate (control).This result was expected since TSP and SAPP have the most alkaline and acid pH respect ively, as compared to the other tested phosphate types (2).The pH is a very important factor as it contributes to the WHC and therefore quality characteristics of cooked meat products, which will be clarifi ed below.

Emulsion stability and cooking loss of cooked sausages
Signifi cant (p<0.05)diff erences in emulsion stability and cooking loss were found between phosphate types (Table 2).Control preparations resulted in high percentage of total expressible fl uid (TEF), which indicates low emulsion stability and high cooking loss, probably due to the inability to hold water because the actomyosin complex is still intact.Polyphosphates, such as SHMP, result in a signifi cant (p<0.05)decrease in cooking loss.This decrease can be explained by the increase in ionic strength by forming polyelectrolytes in water, causing electrostatic repulsion between the meat proteins, and increasing WHC.TSPP and STPP showed signifi cantly (p<0.05)low TEF, indicating the best emulsion stability, as well as the lowest cooking loss.Due to the ability of di-and triphosphates to remove the structural barricade and chelate protein-bound Mg 2+ and Ca 2+ between meat proteins, myosin is released and can possibly act as a natural emulsifier.More proteins could be extracted and help to stabilize the protein matrix wherein fat and water are trapped.This eff ect, in addition to their high pH and their ability to aff ect ionic strength, presumably explains superior TSPP and STPP emulsion stability and signifi cantly (p<0.05)lower cooking loss.SAPP is also a diphosphate, which is able to dissociate the actomyosin complex, albeit possibly to a lesser extent than TSPP and STPP, as suggested by the structural characterization of the meat batt er (see above).Also, in contrast to TSPP and STPP, SAPP addition results in a pH decrease, which decreases WHC.This may explain the lower emulsion stability and higher cooking loss caused by SAPP addition than the addition of TSPP and STPP.Finally, monophosphates are not able to dissociate the actomyosin complex.Still, DSP and TSP are able to reduce cooking loss with respect to the control.This is probably caused by the increase in pH aft er the addition of these phosphates.On the other hand, MSP addition results in the most detrimental product stability, which is probably related to slight acidifi cation caused by this phosphate.
In another study, TSPP and STPP signifi cantly increased pH, WHC, improved emulsion stability and decreased cooking loss of cooked patt ies (22), which corresponds well with the results in this study.

Colour of cooked sausages
Data in Table 2 show that phosphate type signifi cantly (p<0.05)aff ected the cooked sausage colour parameters; however, diff erences in L*, a* and b* values among the diff erent formulations were rather small.Product quality is partly determined by the appearance of cooked meat products in which a stable colour is an important criteria for the consumers' acceptance.Nitrite is added to cured meat products like cooked sausages.Together with the pigment myoglobin, nitrosomyoglobin is produced and is responsible for the dark red colour of cured meat that has not been heated.When nitrosomyoglobin is exposed to heat during cooking, nitrosohemochrome is formed, which has a typical pink colour, characteristic for cured cooked meat products.Based on our results, it seems that aft er cooking, no specifi c type of phosphate should be chosen or avoided to obtain specifi c colour characteristics.The addition of TPP, TSPP and blends had no eff ect on the colour characteristics of goat meat products (26), which is in line with our results.

Eff ect of phosphate type on textural properties of cooked sausages
Data in Table 2 show that only MSP and SAPP significantly (p<0.05)increased hardness of cooked sausages compared to the control.The other phosphate types, such as TSPP, STPP, etc. (Table 2) did not signifi cantly (p<0.05)infl uence hardness compared to the control.
Texture is, apart from colour and jelly separation, also an important factor for consumers' acceptability (3).Hardness can be infl uenced by several factors (30).First, when the extractability of myofi brillar proteins is enhanced, more proteins are available for emulsifi cation and are able to form a more stable gel matrix during heating, which could increase hardness.On the other hand, hardness can also increase due to water or fat loss during processing and storage, which is detrimental to the product quality.In our study, hardness of the preparation with MSP signifi cantly (p<0.05)increased.Addition of MSP also resulted in the greatest cooking loss and the lowest emulsion stability (highest TEF, Table 2).This may explain the increased hardness compared to the sausages with other phosphate types.SAPP has, just like MSP, a low pH value (2).However, emulsion stability and cooking loss were not as detrimental as in the case of MSP.This was possibly due to the fact that SAPP, which is a diphosphate, is able to dissociate the actomyosin complex, extract myofi brillar proteins and enhance emulsifying and gelling properties, which could also enhance hardness of meat products.Therefore, it is assumed that hardness is aff ected by both a good extractability and water and fat loss, as also stated previously (30).
Despite the statistical diff erences, changes in hardness between the diff erent formulations of sausages were relatively small.Therefore, it can be concluded that phosphate type had litt le impact on the sausage textural properties.
TSPP and STPP enhanced texture of cooked patt ies, while SAPP and SHMP had litt le eff ect (21).However, results are diffi cult to compare among the diff erent types of meat products that were evaluated.

Selection of phosphate type for further analyses
The best results with regard to the structural properties and stability (emulsion stability and cooking loss) were obtained with TSPP (diphosphate) and STPP (triphosphate).Diphosphate and triphosphate perform similarly and are excellent functional ingredients for use in meat products (20).Compared to the other phosphate types, TSPP is superior in dissociating the actomyosin complex (3).Therefore, the authors decided to select TSPP as the most promising phosphate for the manufacturing of cooked sausage with the best quality characteristics.TSPP was used as the standard phosphate during the second part of research, in which the amount of TSPP was gradually reduced.

Impact of diff erent mass fractions of TSPP on the quality characteristics of cooked sausages
Structural properties of meat batt ers with TSPP Structural properties were also signifi cantly (p<0.05)infl uenced by the mass fraction of phosphate (Table 3).LVR and G* of sausage batt ers signifi cantly (p<0.05)decreased with increasing phosphate mass fraction, reaching a plateau at 0.06 %.The highest values of LVR and G* were obtained when the control was used, probably because in this case the actomyosin complex was still intact, which led to a 'stronger' system and a higher resistance to deformation.LVR and G* decreased rapidly with increasing mass fractions of added TSPP, which may be att ributed to the fact that TSPP acts strongly on the actomyosin complex due to its chelating characteristics and ability to split the actomyosin complex.The δ signifi cantly increased with increasing phosphate mass fraction, also reaching a plateau at 0.06 %.The lower δ at lower phosphate content presumably indicates that the system showed more liquid-like behaviour.No other studies concerning structural properties related to the amount of phosphate were found.Infl uence of TSPP mass fraction on pH of cooked sausages Phosphate mass fraction signifi cantly (p<0.05)infl uenced the pH of cooked sausages (Table 3).Generally, lowering phosphate mass fraction decreased pH.This was expected since the pH value of TSPP is high (10.2 in a 1 % solution (2)) and higher amounts of TSPP presumably increase pH compared to the control with a pH=6.01.
The pH of patt ies increased progressively with increasing level of phosphate (TSPP, STPP and blends were used) (22), which is in line with our results.

Infl uence of TSPP mass fraction on emulsion stability and cooking loss of cooked sausages
Data in Table 3 show that phosphate mass fraction signifi cantly (p<0.05)aff ected cooking loss and emulsion stability (lower TEF).Phosphate elimination resulted in high cooking loss compared to the preparations with added phosphate.Phosphate reduction also had a negative eff ect on emulsion stability and resulted in higher percentage of TEF; however, this eff ect was less obvious.Even the smallest amount of TSPP led to a tremendous decrease in cooking loss and, however less pronounced, bett er emulsion stability.TSPP can dissociate the actomyosin complex (3), and therefore, probably more myofi brillar proteins were extracted, which possibly led to an improved emulsifi cation of fat droplets and a stronger gel network formation during heating.
The pH, WHC and emulsion stability of patt ies increased progressively with increasing level of phosphate, while cooking loss decreased (22), which is in line with our results.

Infl uence of TSPP mass fraction on colour of cooked sausages
As already discussed in the fi rst part, the impact of phosphate on colour was rather limited.Data in Table 3 indicate that L*, a* and b* showed no clear trend as a function of phosphate mass fraction.

Infl uence of TSPP mass fraction on textural properties of cooked sausages
Hardness of cooked sausages was not infl uenced when the mass fraction of TSPP was reduced from 0.17 to 0.06 %, but a further reduction in its dosage resulted in a small but signifi cant decrease (Table 3).This was possibly due to the fact that TSPP levels lower than 0.06 % were not able to dissociate the actomyosin complex, extract myofi brillar proteins and enhance emulsifying and gelling properties, which in their turn could increase hardness of meat products.In contrast, the control that does not contain TSPP showed an unexpectedly high hardness, which is probably due to the higher cooking loss (6.33 %) of the control than of the cooked sausages prepared with TSPP (cooking loss 0.51 to 1.18 %).The control contained less water, which resulted in a fi rmer product.Overall, hardness of all cooked sausages ranged from 7.0 to 8.6 N and therefore, the eff ect of mass fraction of TSPP on hardness of cooked sausages can be considered as rather limited.
Cooked poultry breast meat batt ers with 2 % NaCl and 0.5 % phosphate showed the highest values of all tex-tural parameters in comparison with meat batt ers without phosphate (20).However, results are diffi cult to compare due to the diff erent type of meat.

Conclusion
The aim of this study was to reduce the amount of phosphate in emulsifi ed meat products with minimal loss of product quality.First, 7 diff erent phosphate types were evaluated.Tetrasodium pyrophosphate (TSPP), a diphosphate, and sodium tripolyphosphate (STPP), a triphosphate, increased pH, improved structural properties, resulted in the highest emulsion stability and lowest cooking loss and had litt le eff ect on textural properties.It was shown that measuring the dynamic viscoelastic properties is a very useful tool to evaluate the quality of meat products, as this method gives insight in the structure of the meat product and especially the functional properties of meat proteins.Based on the structural properties, a minimum mass fraction of 0.06 % was suffi cient to obtain an acceptable qualitative product.However, the exact minimal amount of phosphate needed to obtain good product quality probably depends on the product composition.
In summary, this study shows that the current amount of phosphate added to emulsifi ed meat products can be signifi cantly reduced with minimal loss in product quality.However, in order to maintain product quality without any phosphate added, alternative ingredients such as functional protein are needed.This will be the subject of a future study.

Table 1 .
Dosage of diff erent phosphate types