Determining salt concentrations for equivalent water activity in reduced-sodium cheese by use of a model system

The range of sodium chloride (salt)-to-moisture ratio is critical in producing high-quality cheese products. The salt-to-moisture ratio has numerous effects on cheese quality, including controlling water activity (a_w). Therefore, when attempting to decrease the sodium content of natural cheese it is important to calculate the amount of replacement salts necessary to create the same a_w as the full-sodium target (when using the same cheese making procedure). Most attempts to decrease sodium using replacement salts have used concentrations too low to create the equivalent a_w due to the differences in the molecular weight of the replacers compared with salt. This could be because of the desire to minimize off-flavors inherent in the replacement salts, but it complicates the ability to conclude that the replacement salts are the cause of off-flavors such as bitter. The objective of this study was to develop a model system that could be used to measure a_w directly, without manufacturing cheese, to allow cheese makers to determine the salt and salt replacer concentrations needed to achieve the equivalent a_w for their existing full-sodium control formulas. All-purpose flour, salt, and salt replacers (potassium chloride, modified potassium chloride, magnesium chloride, and calcium chloride) were blended with butter and water at concentrations that approximated the solids, fat, and moisture contents of typical Cheddar cheese. Salt and salt replacers were applied to the model systems at concentrations predicted by Raoult's law. The a_w of the model samples was measured on a water activity meter, and concentrations were adjusted using Raoult's law if they differed from those of the full-sodium model. Based on the results determined using the model system, stirred-curd pilot-scale batches of reduced- and full-sodium Cheddar cheese were manufactured in duplicate. Water activity, pH, and gross composition were measured and evaluated statistically by linear mixed model. The model system method accurately determined the concentrations of salt and salt replacer necessary to achieve the same a_w as the full-sodium control in pilot-scale cheese using different replacement salts.     

Lipolysis in reduced sodium Feta cheese made by partial substitution of NaCl by KCl

Feta cheese (five trials) of different sodium content was made from split lots of curd by varying the salting procedure, i.e. dry salting with NaCl (control) or mixtures of NaCl/KCl (3 : 1 or 1 : 1, w/w basis) and filling the cans with brine made with NaCl or the above NaCl/KCl mixtures, respectively. Lipolysis in cheese was monitored during aging by using the acid degree value (ADV) method and gas chromatography (GC). It was found that the ADVs of control and experimental cheeses were similar (P>0.05) at all sampling ages (3, 20, 40, 60, 120 and 240 d). Moreover, the results of GC showed that there were neither qualitative nor significant (P>0.05) quantitative differences in the individual free fatty acids (FFA) of the control and experimental cheeses at the ages of 40 and 120 d. These findings indicated that the partial substitution of NaCl by KCl in the manufacture of Feta cheese had no effect on lipolysis during cheese aging.     

Generation of volatile compounds in Brazilian low-sodium dry fermented sausages containing blends of NaC1, KC1, and CaC12 during processing and storage

Brazilian dry fermented sausages with different salt contents were manufactured: control (2.5% NaCl), 50% salt reduced (1.25% NaCl, F1), 50% replaced by KCl (1.25% NaCl and 1.25% KCl, F2), 50% replaced by CaCl₂ (1.25% NaCl and 1.25% CaCl₂, F3), and 50% replaced by KCl and CaCl₂ (1.25% NaCl, 0.625% KCl and 0.625% CaCl₂, F4). Changes in the composition of volatile compounds were studied during processing (0, 7, and 19 days) and storage (30, 60, and 90 days). Neither reduction nor replacement of NaCl by KCI affected the volatile compounds produced during the manufacturing process, and both increased the volatile compounds from carbohydrate fermentation and amino acid degradation during storage. The addition of CaCl₂ improved the generation of hexanal and (E)-hept-2-enal and other volatiles from lipid oxidation during processing and storage. After 90 days of storage, the control sample showed an increase in the generation of volatile compounds from lipid oxidation.     

Reduced‐sodium cheeses: Implications of reducing sodium chloride on cheese quality and safety

Sodium chloride (NaCl) universally well‐known as table salt is an ancient food additive, which is broadly used to increase the storage stability and the palatability of foods. Though, in recent decades, use of table salt in foods is a major concern among the health agencies of the world owing to ill effects of sodium (Na) that are mostly linked to hypertension and cardiovascular diseases. As a result, food scientists are working to decrease the sodium content in food either by decreasing the rate of NaCl addition or by partial or full replacement of NaCl with other suitable salts like potassium chloride (KCl), calcium chloride (CaCl₂), or magnesium chloride (MgCl₂). However, in cheese, salt reduction is difficult to accomplish owing to its multifaceted role in cheese making. Considering the significant contribution in dietary salt intake (DSI) from cheese, researchers across the globe are exploring various technical interventions to develop reduced‐sodium cheeses (RSCs) without jeopardizing the quality and safety of cheeses. Thus, the purpose of this study is to provide an insight of NaCl reduction on sensory, physicochemical, and technofunctional attributes of RSCs with an aim to explore various strategies for salt reduction without affecting the cheese quality and safety. The relationship between salt reduction and survival of pathogenic and spoilage‐causing microorganisms and growth of RSCs microflora is also discussed. Based on the understanding of conceptual and applied information on the complex changes that occur in the development of RSCs, the quality and safety of RSCs can be accomplished effectively in order to reduce the DSI from cheese.     

Influence of low-sodium mixtures of salts on the post-salting stage of dry-cured ham process

The reduction of added sodium chloride in dry-cured ham has been proposed to decrease the amount of sodium in the diet. The effect of substituting sodium chloride by potassium chloride, calcium chloride and magnesium chloride in some physicochemical characteristics of dry-cured ham throughout the post-salting stage was evaluated. The partial replacement of NaCl had significant effects on salt content at the end of the post-salting stage in the traditional process and this significantly affected a_w. The results showed that lower sodium hams, salted with a combination of NaCl and KCl, needed a maximum of 16 days more (32% increase) of post-salting than hams salted with 100% NaCl, while hams salted with a combination of NaCl, KCl, CaCl₂ and MgCl₂ needed a maximum of 26 days more (52% increase).     

Effect of NaCl reduction and replacement on the growth of fungi important to the spoilage of bread

The effect of NaCl and various NaCl replacers (CaCl₂, MgCl₂, KCl and MgSO₄) on the growth of Penicillium roqueforti and Aspergillus niger was evaluated at 22 °C. In addition, challenge tests were performed on white bread to determine the consequences of NaCl reduction with or without partial replacement on the growth of P. roqueforti. From the results obtained it can be concluded that at equivalent water phase concentrations the isolates exhibited differing sensitivities to the salts evaluated with NaCl and MgCl₂ having the greatest inhibitory action on the growth of A. niger and P. roqueforti, respectively. MgSO₄ had the least antifungal activity. At equivalent molalities, CaCl₂ had in general the largest antifungal activity. Although the water activity (a_w) lowering effects of the compounds studied play a large role in explaining the trends observed, at equivalent water phase concentrations MgCl₂ was found to have a smaller inhibitory effect on A. niger than that expected from its a_w depressing effect. The challenge tests revealed that no difference occurred in the growth of P. roqueforti on standard white bread, bread with 30% less NaCl and bread in which 30% of the NaCl has been partially replaced by a mixture of KCl and Sub4Salt. These results are of importance in assessing the possible microbiological consequences of NaCl reduction or replacement in bread and similar bakery products.     

Development of a device and method for the time-course estimation of low water fluxes and mean surface water activity of food products during ripening and storage

Accurate measurement of water activity (a_w) is an important goal for the food industry because a_w is a key parameter in microbial growth, biological reaction rates and physical properties. An experimental device was setup using air-product water balance to non-destructively estimate the time-course of mean a_w at the food product surface under well-controlled airflow conditions. The device is especially suited for studying the ripening of cheeses and fermented meat products, where water fluxes exchanged between products and air are very low. The validation tests performed with a_w-known model products showed that water fluxes of 10^?7 kg s^?1 can be estimated with an accuracy better than 2% over very short periods of time, and that surface a_w can be estimated with an absolute uncertainty of less than 0.01 a_w units. A handful of cheese ripening trials illustrate the potential of the method, highlighting the effects of a low air velocity and high air RH on the water exchanges occurring at a cheese surface, thus demonstrating the strong surface sensitivity to external air conditions.     

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.     

The effect of sodium reduction with and without potassium chloride on the survival of Listeria monocytogenes in Cheddar cheese

Sodium chloride (NaCl) in cheese contributes to flavor and texture directly and by its effect on microbial and enzymatic activity. The salt-to-moisture ratio (S/M) is used to gauge if conditions for producing good-quality cheese have been met. Reductions in salt that deviate from the ideal S/M range could result in changing culture acidification profiles during cheese making. Lactococcus lactis ssp. lactis or Lc. lactis ssp. cremoris are both used as cultures in Cheddar cheese manufacture, but Lc. lactis ssp. lactis has a higher salt and pH tolerance than Lc. lactis ssp. cremoris. Both salt and pH are used to control growth and survival of Listeria monocytogenes and salts such as KCl are commonly used to replace the effects of NaCl in food when NaCl is reduced. The objectives of this project were to determine the effects of sodium reduction, KCl use, and the subspecies of Lc. lactis used on L. monocytogenes survival in stirred-curd Cheddar cheese. Cheese was manufactured with either Lc. lactis ssp. lactis or Lc. lactis ssp. cremoris. At the salting step, curd was divided and salted with a concentration targeted to produce a final cheese with 600 mg of sodium/100 g (control), 25% reduced sodium (450 mg of sodium/100 g; both with and without KCl), and low sodium (53% sodium reduction or 280 mg of sodium/100 g; both with and without KCl). Potassium chloride was added on a molar equivalent to the NaCl it replaced to maintain an equivalent S/M. Cheese was inoculated with a 5-strain cocktail of L. monocytogenes at different times during aging to simulate postprocessing contamination, and counts were monitored over 27 or 50 d, depending on incubation temperature (12 or 5°C, respectively). In cheese inoculated with 4 log₁₀ cfu of L. monocytogenes/g 2 wk after manufacture, viable counts declined by more than 3 log₁₀ cfu/g in all treatments over 60 d. When inoculated with 5 log₁₀ cfu/g at 3 mo of cheese age, L. monocytogenes counts in Cheddar cheese were also reduced during storage, but by less than 1.5 log₁₀ cfu/g after 50 d. However, cheese with a 50% reduction in sodium without KCl had higher counts than full-sodium cheese at the end of 50 d of incubation at 4°C when inoculated at 3 mo. When inoculated at 8 mo postmanufacture, this trend was only observed in 50% reduced sodium with KCl, for cheese manufactured with both cultures. This enhanced survival for 50% reduced-sodium cheese was not seen when a higher incubation temperature (12°C) was used when cheese was inoculated at 3 mo of age and monitored for 27 d (no difference in treatments was observed at this incubation temperature). In the event of postprocessing contamination during later stages of ripening, L. monocytogenes was capable of survival in Cheddar cheese regardless of which culture was used, whether or not sodium had been reduced by as much as 50% from standard concentrations, or if KCl had been added to maintain the effective S/M of full-sodium Cheddar cheese.     

Activation energy measurements in rheological analysis of cheese

Activation energy of flow (E_a) between 30 and 44 °C was calculated from temperature sweeps of cheeses with contrasting characteristics to determine its usefulness in predicting rheological behavior upon heating. Cheddar, Colby, whole milk Mozzarella, low-moisture part-skim Mozzarella, Parmesan, soft goat, and Queso Fresco cheeses were heated from 22 to 70 °C, and E_a was calculated from the resulting Arrhenius plots. Protein and moisture content were highly correlated with E_a. The E_a values for goat cheese and Queso Fresco, which did not flow when heated, were between 30 and 60 kJ mol^?1. Cheddar, Colby, and the Mozzarellas did flow upon heating, and their E_a values were between 100 and 150 kJ mol^?1. Parmesan, the hardest cheese, flowed rapidly with heat and had an E_a > 180 kJ mol^?1. E_a provides an objective means of quantitating the flow of cheese, and together with elastic modulus and viscous modulus provides a picture of the behavior of cheese as it is heated.     

Calcium lactate as an attractive compound to partly replace salt in blue-veined cheese

In addition to their high sodium content, cheeses are thought to induce an acid load to the body, which is associated with deleterious effects on consumers' health. Our objective was to explore the use of alkalinizing salts in partial substitution of NaCl to reduce both the sodium content and the acid-forming potential of cheese, without altering its sensory properties. Blue-veined cheeses were produced under industrial conditions, using brine salting followed by dry salting with a 4:1 (wt/wt) mixture of calcium lactate:NaCl or calcium citrate:NaCl. Sodium chloride was used in 2 granulometries: coarse (control treatment) and fine, to obtain homogeneous mixtures with the organic salts. Cheeses were then ripened for 56 d. No major appearance defects were observed during ripening. Calcium lactate substitution decreased the Na content of the cheese core by 33%, and calcium citrate substitution increased the citrate content of the cheese core by 410%, respectively, compared with fine NaCl. This study highlighted the substantial role of salt granulometry in sodium content, with the use of the coarse salt reducing the sodium content by 21% compared with fine salt. Sensory profiles showed nonsignificant differences in bitter and salty perceptions of salt-substituted cheeses with calcium lactate and calcium citrate compared with control cheeses. The use of calcium lactate should be considered to reduce the sodium content and improve the nutritional quality of cheeses while maintaining the sensory quality of the products. Alkalinizing organic salts could replace the acidifying salts KCl or CaCl₂, which are currently used in salt replacement and are not recommended for consumers with renal disease. The method described here should be considered by cheese-making producers to improve the nutritional quality of cheese. Additional nutritional optimization strategies are suggested.     

Effects of Chloride Salts on Appearance, Palatability, and Storage Traits of Flaked and Formed Beef Bullock Restructured Steaks

Restructured steaks made with 0.5 or 1.0% KCl, 0.5% MgCl₂ and 0.5% CaCl₂ were more desirable and darker red in raw color than blends formulated with 0.5 or 1.0% NaCl. Visual properties of raw steaks containing 0.5 or 1.0% chloride salt were scored higher than the control (no salt added) in 14 of 16 orthogonal contrast mean comparisons. Steaks made with 1.0% CaCl₂ or MgCl₂ were rated lower than the control in flavor desirability and overall satisfaction ratings. Control, 0.5 or 1.0% NaCl or 0.5 and 1.0% KCl steaks were not different in juiciness, tenderness, flavor desirability or overall satisfaction ratings. Steaks made with chloride salts were rancid after 70 days frozen storage. Results showed steaks made with KCl were superior to steaks formulated with CaCl₂ or MgCl₂.     

Desorption isotherms of salted minced pork using K-lactate as a substitute for NaCl

The aim of this study was to obtain and compare water desorption isotherms of ground meat containing NaCl (0.107 kg NaCl/kg raw-meat dry matter) and/or K-lactate as NaCl substitute at two different levels of molar substitution (30% and 100%). A thin layer of salted ground meat was dried and sampled at pre-determined times. The moisture content of the samples and their water activities (a_w) were measured at 5 °C and 25 °C. Results showed that ground meat with NaCl and/or different K-lactate contents had a similar water desorption isotherm for a_w ranging from 0.7 to 1.0. Below 0.7, the water equilibrium content fell with small decreases in a_w faster for meat with NaCl than for meat with K-lactate. K-lactate could reduce the excessive hardening at the surface of salted meat products. Experimental desorption isotherms were compared to those estimated using two approaches of the Ross equation. Models provided a good fit for the experimental data.     

Insights into milk-clotting activity of latex peptidases from Calotropis procera and Cryptostegia grandiflora

Latex fractions from Calotropis procera, Cryptostegia grandiflora, Plumeria rubra, and Himatanthus drasticus were assayed in order to prospect for new plant peptidases with milk-clotting activities, for use as rennet alternatives. Only C. procera and C. grandiflora latex fractions exhibited proteolytic and milk-clotting activities, which were not affected by high concentrations of NaCl and CaCl₂. However, pre-incubation of both samples at 75 °C for 10 min eliminated completely their activities. Both proteolytic fractions were able to hydrolyze k-casein and to produce peptides of 16 kDa, a similar SDS-PAGE profile to commercial chymosin. RP-HPLC and mass spectrometry analyses of the k-casein peptides showed that the peptidases from C. procera or C. grandiflora hydrolyzed k-casein similar to commercial chymosin. The cheeses made with both latex peptidases exhibited yields, dry masses, and soluble proteins similar to cheeses prepared with commercial chymosin. In conclusion, C. procera and C. grandiflora latex peptidases with the ability to coagulate milk can be used as alternatives to commercial animal chymosin in the cheese manufacturing process.     

Short communication: Little change takes place in Camembert-type cheese water activities throughout ripening in terms of relative humidity and salt

Water activity (a_w) affects the growth and activity of ripening microorganisms. Moreover, it is generally accepted that a_w depends on relative humidity (RH) and salt content; these 3 variables were usually measured on a given day in a cheese without the microorganism layer and without accounting for a distinction between the rind, the underrind, and the core. However, a_w dynamics have never been thoroughly studied throughout cheese ripening. Experimental Camembert cheeses were ripened under controlled and aseptic conditions (temperature, gaseous atmosphere, and RH) for 14 d. In this study, only RH was varied. Samples were taken from the cheese (microorganism layer)–air interface, the rind, and the core. The a_w of the cheese–air interface did not change over ripening when RH varied between 91 and 92% or between 97 and 98%. However, on d 5, we observed a small but significant increase in a_w, which coincided with the beginning of growth of Penicillium camemberti mycelia. After d 3, no significant differences were found between the a_w of the cheese–air interface, the rind, and the core. From d 0 to 3, cheese rind a_w increased from 0.94 to 0.97, which was probably due to the diffusion of salt from the rind to the core: NaCl content in the rind decreased from 3.7 to 1.6% and NaCl content in the core increased from 0.0 to 1.6%. Nevertheless, a_w did not significantly vary in the core, raising questions about the real effect of salt on a_w.     

Effect of Salt Reduction on Growth of Listeria monocytogenes in Meat and Poultry Systems

Abstract: Reducing sodium in food could have an effect on food safety. The objective was to determine differences in growth of Listeria monocytogenes in meat and poultry systems with salt substitutes. For phase 1, fresh ground beef, pork, and turkey with NaCl, KCl, CaCl₂, MgCl₂, sea salt, or replacement salt added at 2.0% were inoculated with L. monocytogenes to determine growth/survival during 5 d at 4 °C to simulate a pre‐blend process. L. monocytogenes populations significantly decreased (0.41 log CFU/g) during the storage time in beef, but no differences (P > 0.05) were observed over time in pork or turkey. Salt type did not affect (P > 0.05) L. monocytogenes populations during pre‐blend storage. MgCl₂ and NaCl allowed significant growth of aerobic populations during storage. For phase 2, emulsified beef and pork products were processed with 2% NaCl, KCl, sea salt, or a NaCl/KCl blend and post‐process surface‐inoculated with L. monocytogenes to determine growth/survival at 4 °C for 28 d. Pork products showed significantly greater L. monocytogenes population growth at all sampling times (0, 7, 14, 21, and 28 d) than beef products, but salt type had no effect on L. monocytogenes populations with sampling times pooled for data analysis. Although salt types had no impact on L. monocytogenes populations in preblend and emulsified meat products, pork and turkey preblends and emulsified pork had greater L. monocytogenes populations compared with beef products. These studies demonstrate that sodium may not affect the safety of preblends and emulsified meat and poultry products. Practical Application: odium reduction in food is an important topic because of sodium's unfavorable health effects. This research shows that reducing sodium in pre‐blends and emulsified meat and poultry products would have no effect on Listeria monocytogenes populations, but replacement of NaCl with MgCl₂ may affect growth of aerobic populations.     

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.     

Tomato peeling by ohmic heating: Effects of lye-salt combinations and post-treatments on weight loss,peeling quality and firmness

Ohmic heating without lye has shown promise in tomato peeling; however the use of lye is known to yield high peeled-product quality. This investigation was aimed at determining whether a combination of ohmic heating and low lye concentrations could be synergistic. The results indicated that 0.01/0.5% NaCl/KOH at 2020 V/m was the best condition for tomato peeling in terms of quality, weight loss, and peel cracking time. Further, the treatment showed weight loss that was not significantly different from conventional lye peeling at 7% NaOH and 7% KOH (p < 0.05). NaCl/NaOH mixtures also showed good results, but the quality of products was lower than that using the same concentration, but a higher field strength with NaCl/KOH mixtures. However, no improvement was found using NaCl/CaCl₂ and NaCl/NaOH/CaCl₂ mixtures which were also found difficult to use due to turbidity and cleaning difficulties. A post-peeling treatment by ohmic heating was investigated to improve firmness of ohmically peeled tomatoes. It was found that the best conditions were 2% CaCl₂ solution at a field strength of 403 V/m for 1 and 5 min, and 484 V/m for 5 min.Industrial RelevanceOur earlier work had shown that ohmic heating resulted in peeling of tomatoes that were immersed in salt solutions. The current work details the impact of using small concentrations of lye (either sodium or potassium hydroxide) on peeling loss and quality. Also, we investigate the potential use of calcium chloride, both as peeling solution or as a post-peeling infusion as it impacts firmness of tomatoes. We show that there are ranges of operating conditions which provide yield and quality comparable to conventional lye peeling at far lower lye concentrations, resulting in potentially significant environmental benefit to companies currently using lye peeling.     

Effect of Partial Substitutes of NaCl on the Cold-Set Gelation of Grass Carp Myofibrillar Protein Mediated by Microbial Transglutaminase

The objectives of this study were to investigate the changes and the relationship between structure and physiochemical properties of low sodium salt substitutes (NaCl partially replaced by KCl, CaCl₂, and MgCl₂) on grass carp myofibrillar protein gels mediated by microbial transglutaminase during cold-set gels and to provide more information about the gel characteristics. The gel strength, water holding capacity, whiteness, rheological characteristics, differential scanning calorimeter (DSC), and Raman spectra of cold-set gels were determined. The Raman spectra data were fitted to four secondary structures (α-helix, β-sheet, β-turn, and random coil). The gel properties of cold-set gels varied both with the low sodium salt types and incubation time. Myofibrillar protein (MP) gels added with NaCl and KCl had significantly higher water holding capacity than the MgCl₂, CaCl₂, and control groups. Additionally, the results showed that the gel strength and G’ value increased with the incubating time. No significant difference was detected in whiteness between the NaCl group and partial substituted groups. Cold-set gels added with the same molar amount of NaCl and KCl had fairly similar gel properties. There is a strong correlation between structural properties and gel properties of MP gels determined by DSC during the cold-set gelation process.