Effect of ionic strength of different salts on the binding of volatile compounds to porcine soluble protein extracts in model systems

The effect of different salts on the binding ability of porcine soluble protein extracts was studied using solid-phase microextraction (SPME) and GC/MS analysis. Previously, the effect of the different salts (NaCl, KCl, MgCl₂ and CaCl₂) on the volatile compound headspace concentration in water solution was determined. KCl produced a similar salting out effect as NaCl increasing the volatile compound headspace concentration up to 5–10 times. However, MgCl₂ and CaCl₂ did not produce a salting out effect on the volatile compounds studied. Finally, NaCl and KCl produced a significant reduction on the binding ability of sarcoplasmic protein extracts to branched aldehydes, hexanal and methional while no effect was produced on octanal and 2-pentanone. On the other hand, the effect of MgCl₂ and CaCl₂ was much lower even at high ionic strength, except for the branched aldehydes where the presence of MgCl₂ at 1.0 ionic strength produced the complete liberation of the volatile compound bound. Consequently, the partial NaCl substitution in meat products by other salts must be considered not only due to their salting out effect but also due to their effect on protein binding ability.     

Myofibrillar Protein Solubility of Model Beef Batters as Affected by Low Levels of Calcium, Magnesium and Zinc Chloride

Preblended composites of semimembranosus and adductor muscles were stored 12h at 4°C with 2.0% NaCl, 0 or 0.05% CaCl₂, MgCl₂, or ZnCl₂ and 0 or 0.4% sodium tripolyphosphate (STPP). Model systems were formulated to contain 30% fat (high fat; HF) or 10% fat (low fat; LF). Divalent salts lowered extract pH and ZnCl₂ elicited the greatest reduction. At both fat levels, CaCl₂ increased and ZnCl₂ decreased protein solubility, compared to the control (p<0.05). Myosin was not detected in ZnCl₂-treated HF and LF batters without STPP and in the presence of STPP, MgCl₂ and ZnCl₂ increased myosin concentration at both fat levels (p<0.05). Zinc chloride increased actin concentration in HF batters; whereas, MgCl₂ decreased soluble actin in LF batters (p<0.05). Magnesium chloride (0.05%) increased soluble proteins in LF batters containing 0.4% STPP by increasing myosin extractability.     

Textural properties and microstructure of low-fat and sodium-reduced meat batters formulated with gellan gum and dicationic salts

Instrumental texture characteristics of low-fat, reduced-sodium meat batters formulated with other salts (KCl and MgCl₂ or CaCl₂) with gellan gum were evaluated. Fat and sodium reduction through incorporation of gellan gum and either of the dicationic salts produced less rigid, more ductile structures. Inclusion of magnesium chloride resulted in better performance, whereas addition of calcium chloride resulted in less desirable properties. The dicationic salts level used probably inhibited the gellan gum thermoreversible properties, affecting its water holding properties. Microstructural differences between the dicationic salt treatments were apparently due to the effect of dicationic salt concentration on myofibrillar protein extraction and solubilization, and gellan gum gelation properties. Use of magnesium chloride in tandem with gellan gum in the studied low-fat, reduced-sodium meat batters effectively compensated for the structural differences caused by fat and sodium reduction.     

Protein Extractability of Turkey Breast and Thigh Muscle with Varying Sodium Chloride Solutions as Affected by Calcium, Magnesium and Zinc Chloride

Ground turkey breast and thigh muscle were extracted with various NaCl solutions with or without added CaCl₂, MgCl₂, or ZnCl₂ (0.05%). Protein solubility was increased by CaCl₂ and decreased by ZnCl₂ in each muscle type. At 4% NaCl, MgCl₂ increased thigh myosin solubility by 30%, compared to the control, whereas CaCl₂ had no effect. At 2% and 4% NaCl, breast myosin was not affected by MgCl₂ or CaCl₂. Myosin was not detected for either muscle type when ZnCl₂ was used. All three salts increased breast actin solubility but only MgCl₂ increased thigh actin solubility. The CaCl₂ resulted in the highest overall protein solubility and MgCl₂ resulted in the highest thigh myosin and actin solubility at 4% NaCl.     

Use of a D-optimal mixture design to estimate the effects of diverse chloride salts on the growth parameters of Lactobacillus pentosus

The effects of NaCl, KCl, CaCl₂, and MgCl₂ and their mixtures on the ionic strength (IS) of the medium and the growth parameters of Lactobacillus pentosus were studied by means of a D-optimal mixture experimental design with constrains (total salt concentration ≤ 9.0%, wt/vol) and the generalized z-value. The IS was linearly related to the concentrations of the diverse salts and its increase, for similar concentrations of salts, followed the order MgCl₂ > CaCl₂ > NaCl > KCl. Within the experimental region, the lag phase duration (λ) was mainly affected by NaCl and CaCl₂ and the interaction KCl with MgCl₂. The maximum specific growth rate (μ_max) decreased as NaCl (the highest effect), CaCl₂, and MgCl₂ increased (regardless of the presence or not of previous NaCl); low KCl concentrations had a stimulating effect on μ_max, but its overall effect showed a similar trend to the other salts. The maximum population reached (N_max) was the least affected parameter and decreased as NaCl and CaCl₂ concentrations increased regardless of the presence of the other salts. The equations that expressed the growth parameters as a function of the diverse chloride salts, within the limits assayed, were developed and the corresponding z- and harmonic Z-values were estimated.     

Cook Yield, Texture and Gel Ultrastructure of Model Beef Batters as Affected by Low Levels of Calcium, Magnesium and Zinc Chloride

Effects of 0.05% CaCl₂, MgCl₂, or ZnCl₂, with or without 0.4% sodium tripolyphosphate (STPP), were investigated in high fat (HF; 30% fat) or low fat (LF; 10% fat) model beef batters. Cook yield (CY), texture, and gel ultrastructure were evaluated. With STPP, CaCl₂ increased CY, and in the absence of STPP, ZnCl₂ decreased CY and cohesiveness (p<0.05). Low-fat, ZnCl₂-treated batters without STPP had the lowest (p<0.05) hardness. Addition of STPP resulted in a homogeneous matrix in HF batters. In MgCl₂-treated HF batters, protein film surrounding fat globules had greater integrity than control, CaCl₂ or ZnCl₂ treatments. In ZnCl₂-treated HF batters (without STPP) a protein sheet was present without evidence of film encased droplets. Low-fat batters with STPP had finer, more porous networks than those without STPP.     

Rheological and Gelation Properties of Meat Batters Prepared with Three Chloride Salts

The gelation and rheological properties of poultry meat emulsions prepared with three chloride salts (NaCl, KCl, MgCl₂) and 50/50 mixtures of the above salts at isoionic strength (IS = 0.42) were studied. The relationship between shear rate and shear stress for the different raw meat emulsions was found to be nonlinear and followed Bingham pseudoplastic behavior. The yield stress for the emulsion containing only MgCl₂ was significantly lower as compared to all the other treatments. The highest rigidity modulus values obtained during cooking were observed in the NaCl + MgCl₂ treatment followed by the NaCl + KCl, NaCl and KCl. The emulsion containing MgCl₂ only broke down at the initial stages of cooking, exhibiting the destabilizing effect of the magnesium cation.     

Effects of Ca++, Mg++ and Na+ on Heat Aggregation of Whey Protein Concentrates

Effect of Ca⁺⁺ on the heat aggregation of whey protein concentrates (WPC) was compared with that of Na⁺ and Mg⁺⁺. On the alkaline side of the isoelectric zone, aggregation of WPC was increased by the addition of CaCl₂, MgCl₂ or NaCl, among which CaCl₂ showed the greatest effect. The denaturation temperature of WPC determined by differential scanning calorimetry significantly decreased in the presence of CaCl₂ or MgCl₂, but increased slightly in the presence of NaCl. In the electrophoretic patterns of heated WPC, the most sensitive protein to Ca⁺⁺ was β-lactoglobulin.     

Rheological changes during thermal gelation of meat batters containing surimi from alaska pollack (Theragra chalcogramma) or sardine (Sardina pilchardus)

The objective of this study was to use a thermal scanning rigidity monitor to analyse the changes occurring in rheological behaviour during thermal gelation induced by the presence of surimi in meat batters. These studies were conducted on systems prepared with pork meat to which varying proportions of surimi from Alaska pollack (Theragra chalcogramma (Pallas)) or sardine (Sardina pilchardus) (Walb) were added. The results indicated that gelation in pork proteins did not occur in the same way as in fish proteins. Whereas the addition of Alaska pollack surimi to the meat preparations produced scarcely any change with respect to the meat alone, the sardine surimi caused major alterations. These changes depended upon the proportion of protein from surimi added: addition of 100 g kg^?1 caused a protein matrix to form, inducing the formation of stiffer gels and the appearance of the setting phenomenon, although at higher temperatures than are found with fish proteins. Such behaviour was not apparent when the proportion of protein from surimi was raised to 200 g kg^?1.     

Effect of pH and NaCl/CaCl2 on the solubility and emulsifying properties of sweet potato protein

BACKGROUND: The effects of NaCl and CaCl₂ on the solubility and emulsifying properties, namely emulsifying activity index (EAI) and emulsion stability index (ESI) of sweet potato proteins (SPPs) at pH 1–10, were investigated. RESULTS: At lower NaCl (0.1 mol L^?1) and CaCl₂ (0.05 mol L^?1) concentrations, the solubility profiles of the SPPs were very similar to those in distilled water, and the lowest solubility occurred at pH 4. Increased NaCl and CaCl₂ concentration resulted in lower SPP solubility in most of the pH studied (P < 0.05). At pH < 3, NaCl improved the EAI of SPP while at pH > 7 it reduced the EAI of the SPP (P < 0.05). Moreover, addition of NaCl also resulted in reduction of ESI of the SPP in most of the pH studied (P < 0.05). On the other hand, the presence of 0.2 mol L^?1 CaCl₂ rendered the EAI and ESI of the SPPs independent of the influence of pH. CONCLUSION: The present studies show that pH and salts modified the emulsifying properties of the SPPs, and CaCl₂ at a certain concentration could be used to improve the emulsifying properties of the protein. Copyright © 2008 Society of Chemical Industry     

Effect of sodium,potassium, calcium and magnesium chloride salts on porcine muscle proteases

This study is focused on the effect of sodium chloride alternative salts (KCl, MgCl₂ and CaCl₂) on porcine muscle proteases (cathepsins, dipeptidylpeptidases and aminopeptidases). In general, KCl exerted a very similar effect to NaCl for all the studied enzymes, while the effect of divalent salts (CaCl₂ and MgCl₂) was more pronounced. Cathepsins, dipeptidyl peptidase III, dipeptidyl peptidase IV and alanyl aminopeptidase activities were strongly inhibited by all the chloride salts especially by divalent ones. Dipeptidyl peptidase II and leucyl aminopeptidase were little affected and methionyl aminopeptidase was only inhibited by divalent salts. Dipeptidyl peptidase I was strongly activated by low concentrations of the chloride salts except NaCl. Arginyl aminopeptidase was activated by NaCl and KCl and low amounts of MgCl₂, while CaCl₂ showed a strong inhibitory effect. This is very important as these enzymes play important roles in dry-cured meats and their activity is, in general, regulated by sodium chloride. Thus, reductions in the sodium concentration with subsequent increases of other alternative cations may have relevant consequences on enzyme activity that should be taken into account when processing dry-cured meats.     

Effect of soaking with hydrogen peroxide and carbonate/bicarbonate buffer solutions on chemical composition and protein extractability of desalted cod

Cod salted with various combinations of NaCl, KCl, MgCl₂ and CaCl₂ were soaked for the first 24 h with a 0.2 M carbonate buffer solution (pH 9.5) or for the first 5 h with 1% hydrogen peroxide (pH 7.16). Chloride, ions and ash content in muscle were measured during the soaking process. After soaking, the composition of soluble muscle protein extracted in NaCl 0.86 M was determined by SDS-PAGE. The divalent, cation content was not affected by the salting and soaking processes. The protein extractability was low, especially when H₂O₂ was used. The use of alkaline buffer solution produced better protein functional quality. When the alkaline solution was used for soaking, the soluble fraction was constituted of a larger variety of proteins. Actin was soluble only when MgCl₂ and KCl were used for salting and the alkaline solution for soaking. The use of carbonate/bicarbonate buffer solution for soaking could therefore be useful to improve the functional quality of muscle protein of desalted cod.     

Influence of alginate and microbial transglutaminase as binding ingredients on restructured fish muscle processed at low temperature

BACKGROUND: In view of the increasing demand for fresh products in Western countries recently, there is considerable interest in commercialising restructured fish products having the appearance of fresh fish. A number of methods have been studied for the purpose of inducing cold gelification. Two of the most common methods, namely addition of alginates and addition of transglutaminases, have been studied mainly in connection with meat products. The present study deals with the use of alginate and transglutaminase as additives in cold gelification of minced hake (Merluccius capensis) muscle. The experiments were targeted on the effects of concentration and combined effects of additional additives on physicochemical characteristics and mechanical properties. RESULTS: As regards mechanical properties, the effectiveness of sodium alginate was improved by addition of a low concentration (1 g kg^?1) of calcium chloride (CaCl₂), whereas a higher concentration (10 g kg^?1) reduced the binding ability of the alginate. The presence of sodium caseinate (15 g kg^?1) in combination with microbial transglutaminase (MTGase) was important in helping to increase the work of penetration in fish gels induced at low temperature. Examination of the chemical properties of the muscle gels showed that sodium alginate did not establish covalent protein–protein bonds, while MTGase dramatically increased the number of covalent bonds formed between adjacent muscle proteins. CONCLUSION: With both ingredients, thermostable fish gels of good quality were produced at temperatures below 10 °C. Gels induced by sodium alginate were considerably improved by addition of 1 g kg^?1 CaCl₂. However, gels induced by MTGase were better suited for the preparation of restructured products. Copyright © 2008 Society of Chemical Industry     

ANTIMICROBIAL EFFECTS OF SODIUM AND OTHER IONS IN FOODS: A REVIEW1

Salt or sodium chloride (NaCl) is a common ingredient in many processed foods, and especially in cured meats. In addition to flavoring and functional contributions, NaCl is believed to play an important antimicrobial role in these products. The antimicrobial activity of NaCl is reviewed in light of currrent calls for a reduction of Na⁺ in the human diet due to health reasons, and the possible replacement of NaCl in processed foods with chloride salts of other ions (i.e. KCl, MgCl₂, CaCl₂). Factors interacting with NaCl and complicating the nature of the preservative system in processed foods are examined; recent work with alternative chloride salts is summarized; complex solute-water activity interactions are highlighted; and, several important factors are considered in relation to the antimicrobial effects of NaCl and the possibility of its replacement with other chloride salts.     

Comparison of immunohistochemical,histochemical and immunochemical methods for the detection of wheat protein allergens in meat samples and cooked,dry, raw and fermented sausage samples

Nowadays is it a common practice to add vegetable protein in the production of meat products. Because of the possible substitution of high-quality raw meat with vegetable protein without the labelling the product package and because of the allergenic potential of many vegetable proteins, it is important to develop accurate methods for its detection. The objective of the study was to compare histochemical, immunochemical (ELISA, ALERT gliadin screening test) and immunohistochemical methods for the detection of wheat protein in meat samples and sausages. Histochemical methods were useful for the detection of flour in meat samples, but the immunohistochemical method was better for the detection of wheat protein. ALERT gliadin screening test detected gliadin from 10?mg?kg^?1, while an immunohistochemical method detected wheat protein concentrations from 1?g?kg^?1 and an ELISA method detected wheat protein concentrations from 4?g?kg^?1. ALERT gliadin screening test showed results within 1 day, whilst an ELISA detection method took 2 days, and an immunohistochemical procedure took 5 days at the soonest, all including sample preparation. This study also focused on optimisation of an immunohistochemical method for samples of cooked sausage. In addition, three samples were sufficient for wheat protein detection at a concentration of 1?g?kg^?1 (and greater) with a confidence level greater than 95%.     

Effect of brine salting at different pHs on the functional properties of cod muscle proteins after subsequent dry salting

Fillets of Atlantic cod (Gadus morhua) were wet-salted in brines of pH 6.5 and 8.5 containing different combinations of NaCl, KCl, MgCl₂ and CaCl₂, then dry-salted in NaCl. Proximate analyses, functional properties (water holding capacity and protein solubility) and hardness were determined in the dry-salted cod. The compositions of the protein fractions soluble in water and in 0.86 M sodium chloride were determined by SDS–PAGE. The composition and pH of the brines slightly affected the protein composition of the major extract constituents and the functional properties of the muscle after dry-salting. Brining at alkaline pH produced a larger variety of water-soluble proteins, particularly actin, than at pH 6.5. Furthermore, the compositions of the protein fractions extracted with 0.86 M NaCl were very similar for both pHs, irrespective of the composition of the brine; in this case, myosin heavy chains were absent in both extracts due to aggregation caused by a massive uptake of salt by the muscle.     

Physicochemical and functional properties of a protein isolate produced from safflower (Carthamus tinctorius L.) meal by ultrafiltration

BACKGROUND: The protein isolate obtained from safflower meal by aqueous extraction and ultrafiltration was evaluated for its physicochemical and functional properties. RESULTS: Protein, ash and moisture contents of the safflower protein isolate were 901, 51 and 45 g kg^?1 respectively. Its water and oil absorption capacities were 2.22 mL H₂O g^?1 protein and 2.77 mL oil g^?1 protein respectively. Least gelation concentration was 20 g kg^?1 at pH 2, 6, 8 and 10 but 100 g kg^?1 at pH 4. Emulsifying properties were also affected by the pH: emulsifying activity and emulsion stability at pH 6 were 82.5 and 100% respectively. The highest foaming capacity (126%) occurred at pH 2; however, it increased by 104% with the addition of 0.25 g glucose g^?1 protein to the foam system. CONCLUSION: In the light of its functional properties found in this study, safflower protein isolate produced by ultrafiltration is recommended for use as an ingredient in food products such as salad dressing, meat products, mayonnaise, cakes, ice cream and desserts. Copyright © 2010 Society of Chemical Industry     

Effect of calcium salts on the texture,structure and sensory acceptance of osmotically dehydrated guavas

The effect of additives, calcium chloride and calcium lactate (5–25 g kg^?1), on the osmotic dehydration of guavas with sucrose solutions was studied, aiming at the structural preservation of processed fruits. The osmotic process was evaluated from the reduction in weight of the guavas, water loss and solids gain, and the samples were analyzed with respect to calcium content, texture (stress and strain at failure, relaxation time and residual stress), structure by light microscopy and sensory acceptance. Calcium salts had a strong influence on the texture and structure of the processed guavas, resulting in the maintenance of tissue structure when calcium lactate was used at concentrations up to 15 g kg^?1, and calcium chloride was used at 5 g kg^?1. The sensory acceptability of guava was related to the structural and texture results. Calcium treatments did not improve guava's sensory acceptance. Guavas treated with calcium lactate showed good sensory acceptance, presenting slight inferior scores only at concentrations above 20g kg^?1, while CaCl₂ treated guavas showed average scores statistically equal to the sucrose and calcium lactate treated fruits only at 5 g kg^?1. Copyright © 2007 Society of Chemical Industry     

Influence of sucrose on cold gelation of heat‐denatured whey protein isolate

A solution of heat‐denatured whey proteins was prepared by heating 100 g kg⁻¹ whey protein isolate (WPI) at pH 7.0 to 75 °C for 15 min in the absence of salt. Heat treatment caused the globular protein molecules to unfold, but electrostatic repulsion opposed strong protein–protein aggregation and so prevented gel formation. When the heat‐denatured whey protein solution was cooled to room temperature and mixed with 15 mM CaCl₂, it formed a gel. We investigated the influence of the presence of sucrose in the protein solutions prior to CaCl₂ addition on the gelation rate. At relatively low concentrations (0–100 g kg⁻¹), sucrose decreased the gelation rate, presumably because sucrose increased the aqueous phase viscosity. At higher concentrations (100–300 g kg⁻¹), sucrose decreased the gelation rate, probably because sugar competes for the water of hydration and therefore increases the attraction between proteins. These data have important implications for the application of cold‐setting WPI ingredients in sweetened food products such as desserts. © 2000 Society of Chemical Industry     

Combination treatment of high-pressure and CaCl2 for the reduction of sodium content in chicken meat batters: effects on physicochemical properties and sensory characteristics

A combination of high-pressure processing (HPP, 200 MPa, 10 min) and CaCl₂ (0.2%, w/w) on the cooking loss (CL), expressible moisture (EM), textural properties (hardness, springiness, cohesiveness, chewiness and firmness) and sensory attributes of reduced-sodium (1.25% NaCl) chicken meat batters (RCMB) was investigated. The results revealed that combining HPP with CaCl₂ significantly decreased EM, elevated sensory properties and acted synergistically in reducing CL and improving hardness, chewiness and firmness, which enabled RCMB to obtain quality characteristics similar to those with high salt (2.5% NaCl) content. These changes brought about by combined HPP and CaCl₂ could be attributed to increased apparent viscosity and proportion of immobilised water, enhanced rheological (elastic) properties and a denser, homogeneous protein gel network with evenly dispersed small fat globules. It is interesting to take advantage of the synergy between moderate HPP and low concentrations of CaCl₂ to develop meat products with reduced sodium content.