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.     

Glass transition and crystallization behaviour of freeze-dried lactose-salt mixtures

Glass transition temperatures were determined for dehydrated lactose/salt mixtures with various water contents and water activities, and state diagrams were established. Crystallization behaviour was studied for pure amorphous lactose stored at various relative water vapour pressures (RVP). Furthermore, glass transitions temperatures and time-dependent lactose crystallization of freeze-dried lactose and lactose/CaCl₂, lactose/NaCl, lactose/MgCl₂ and lactose/KCl mixtures in molar ratios of 9:1 were determined. Glass transition temperatures (T_g) of lactose powder as determined by differential scanning calorimetry (DSC) was lower than that of lactose/CaCl₂ (9:1)_, and lactose/MgCl₂ (9:1), but it was slightly higher than the T_g of lactose/NaCl (9:1), and lactose/KCl (9:1). Lactose/KCl had the lowest glass transition temperature, but it had about the same crystallization temperature as lactose/NaCl, and lactose/MgCl₂. The glass transition temperatures decreased as water contents increased. The critical water contents and water activities at 23 °C were predicted using data on glass transition temperature and water sorption. Pure lactose had a different critical water activity and water content from lactose/salt mixtures. The critical values of lactose/CaCl₂ (9:1) were the highest. Loss of sorbed water, indicating lactose crystallization, was observed in lactose and lactose/salt mixtures stored above the critical RVP.     

Water sorption and time-dependent crystallization behaviour of freeze-dried lactose-salt mixtures

Water sorption properties of freeze-dried lactose, lactose/CaCl₂, lactose/NaCl, lactose/MgCl₂, and lactose/KCl mixtures in their molar ratio of (9:1) were investigated. Brunauer-Emmett-Teller (BET) and Guggenheim-Anderson-de Boer (GAB) models were used to model water sorption properties. Water is known to function as a plasticizer, depressing the glass transition and facilitating crystallization. Crystallization in the present study resulted in loss of sorbed water from lactose. The crystallization of pure lactose and lactose/salt mixtures was observed at RVP?44.0% within 24 h. At RVP?54.4% water contents were higher in lactose/CaCl₂ and lactose/MgCl₂ mixtures than in pure lactose, lactose/NaCl, and lactose/KCl.Water content in pure lactose after crystallization was ?5.0%, suggesting that lactose crystallized as a mixture of α-lactose monohydrate and various anhydrous forms of α/β-lactose crystals. Anhydrous lactose/CaCl₂ and lactose/MgCl₂ had higher glass transition temperatures than lactose, but other salts (NaCl and KCl) with lactose gave lower glass transition than amorphous lactose. It seems that bivalent salts in mixtures with lactose gave a higher T_g than smaller monovalent ions. Salts delayed lactose crystallization. The effect on lactose crystallization was highest with calcium chloride (CaCl₂) and lowest with potassium chloride (KCl). It seems that different salts interacted with lactose to different extents. For water sorption, GAB model gave a better fit than BET model. Water sorption and time-dependent crystallization properties of lactose/salt mixtures should be considered in manufacturing and storage of dairy-based dehydrated materials.     

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.     

Evaluation of the efficacy of four weak acids as antifungal preservatives in low-acid intermediate moisture model food systems

The potential efficacy of four weak acids as preservatives in low-acid intermediate moisture foods was assessed using a glycerol based agar medium. The minimum inhibitory concentrations (MIC, % wt./wt.) of each acid was determined at two pH values (pH 5.0, pH 6.0) and two a_w values (0.85, 0.90) for five food spoilage fungi, Eurotium herbariorum, Eurotium rubrum, Aspergillus niger, Aspergillus flavus and Penicillium roqueforti. Sorbic acid, a preservative commonly used to control fungal growth in low-acid intermediate moisture foods, was included as a reference. The MIC values of the four acids were lower at pH 5.0 than pH 6.0 at equivalent a_w values, and lower at 0.85 a_w than 0.90 a_w at equivalent pH values. By comparison with the MIC values of sorbic acid, those of caprylic acid and dehydroacetic acid were generally lower, whereas those for caproic acid were generally higher. No general observation could be made in the case of capric acid. The antifungal activities of all five weak acids appeared related not only to the undissociated form, but also the dissociated form, of each acid.     

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.     

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 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.     

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.     

Phytic Acid Hydrolysis and Soluble Zinc and Iron in Whole Wheat Bread As Affected by Calcium Containing Additives

The effects of nonfat dry milk, CaCO₃, CaCl₂ and MgCl₂ on phytate hydrolysis and on Zn and Fe availability was evaluated in whole wheat bread and in a model fermentation system. CaCO₃ and CaCl₂ both depressed phytate hydrolysis to an equivalent degree, but the milk had a greater effect than could be accounted for by its Ca content. MgCl₂ had a less pronounced effect than the Ca salts in both the bread and the model system. Increasing fermentation time in the model system increased phytate hydrolysis, but the effect was delayed when milk or CaCl₂ was added. Supplementing the bread dough with Ca equivalent to that typically contributed by Ca-containing additives caused 50% reductions in the available quantities of soluble (“free”) zinc and iron; the decreases observed with varying added amounts of Ca or milk exhibited a high degree of correlation with the observed increases in residual phytate P.     

A study on the implications of NaCl reduction in the fermentation profile of Conservolea natural black olives

This study examined the impact of different mixtures of NaCl, KCl, and CaCl₂ on the fermentation profiles of Conservolea natural black olives. Five different combinations of chloride salts were investigated, namely (i) 8% NaCl (control treatment), (ii) 4% NaCl and 4% KCl, (iii) 4% NaCl and 4% CaCl₂, (iv) 4% KCl and 4% CaCl₂, and (v) 2.6% NaCl-2.6% KCl-2.6% CaCl₂. The changes in the microbial association (lactic acid bacteria, yeasts, Enterobacteriaceae), pH, titratable acidity, organic acids, volatile compounds, and mineral content in olive flesh were analyzed. Results demonstrated that all salt combinations led to vigorous lactic acid processes based on the obtained values of pH (3.9-4.2) and titratable acidity (0.70-0.86 g lactic acid per 100 ml brine). Organoleptic evaluation was a critical factor in the acceptability of the final product. Increasing concentrations of CaCl₂ or a combination of KCl and CaCl₂ rendered the product bitter with low acceptability by the taste panel. Only one combination of chloride salts (4% NaCl and 4% KCl) could finally produce olives with lower sodium content and good organoleptic attributes. The results of this study could be employed by the Greek table olive industry in an attempt to produce natural black olives with less sodium without affecting the traditional taste of fermented olives in order to meet consumers’ demand for low sodium dietary intake.     

Effect of chloride salts on protein extraction and interfacial protein film formation in meat batters

Six comminuted chicken breast meat mixes and six meat batters were made with isoionic NaCl (25 g kg^?1), MgCl₂, CaCl₂, KCl, LiCl (IS = 0.43) and 15 g kg^?1 NaCl (IS = 0.26). The quantity and type of proteins extracted and used for interfacial protein film (IPF) formation was determined and related to batter stability. The monovalent salts produced IPF which differed in individual protein content between salts but which all contained significantly larger amounts of protein (P < 0.01) than those using divalent salts. MgCl₂ extracted more protein than CaCl₂ and produced a different protein profile in the IPF. However, MgCl₂ formed unstable raw batters whereas CaCl₂ did not. In addition, a simple, rapid method for extracting and quantifying proteins from meat batters was developed to assist in direct determination of the actual soluble protein uptake by the fat phase during comminution.     

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.     

Biochemical and sensory changes in dry-cured ham salted with partial replacements of NaCl by other chloride salts

The reduction of the content of sodium chloride in dry-cured ham was studied in to prevent the problems related to high sodium intake (i.e. the hypertension). One of the possibilities to reduce the sodium content is the partial replacement of sodium chloride by mixtures of potassium, magnesium and calcium chloride salts. The effect of two salting formulations (formulation II: 50% NaCl-50% KCl and formulation III: 55% NaCl, 25% KCl, 15 CaCl₂ and 5 MgCl₂) on the protease activity through the dry-curing process and on the sensory characteristics of the final product was evaluated and compared to those of control hams (formulation I, 100% NaCl). Sensory attributes were all affected in the hams containing CaCl₂ and MgCl₂ while hams containing 50% KCl and NaCl (formulation II) were better valued, except for the attribute taste probably due to the potassium contribution to bitter taste.     

Vapor pressure and water activity measurements of saturated salt solutions made with D2O at 20°C

The water activity (a_w) values of 10 saturated salt solutions made with D₂O were measured in this study at 20°C: MgCl₂, K₂CO₃, Mg(NO₃)₂, KI, NaCl, KCl, ZnSO₄, BaCl₂, KNO₃, and K₂SO₄. These salts were selected because they represent a wide range of water activity values, from approximately 0.33 to 0.98. The a_w values were measured using two methods: (1) a vapor pressure manometer, and (2) an electronic chilled-mirror (AquaLab) instrument. The a_w values obtained by the manometer method were slightly, but consistently, higher than the a_w values obtained by the electronic chilled-mirror instrument. The a_w values of the saturated salt solutions made with D₂O (as measured by both methods) were also slightly, but consistently, higher than the a_w values of the same saturated salt solutions made with H₂O at 20°C. ©     

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.     

BALANCING MACROMINERAL COMPOSITION OF FRESH-PACK CUCUMBER PICKLES TO IMPROVE NUTRITIONAL QUALITY AND MAINTAIN FLAVOR1

The macromineral nutritional balance of fresh-pack dill cucumber pickles was improved without loss of flavor quality. A product with flavor acceptability equal to the original product was obtained if NaCl was reduced by 40%, from 2.0% to 1.2%. To replace the 0.8% reduction in NaCl 0.8% KCl was added. CaCl₂ and MgCl₂ were added proportionately to match the daily value (DV) of the added KCl. In addition to changes in mineral composition, low levels of both citric acid and hot pepper sauce were added to improve flavor acceptability. The flavor acceptability of dill pickles was rated higher (P <0.05) than the 2.0% NaCl control when the NaCl concentration was reduced 20% from 2.0 to 1.6%, and 0.4% KCl was added to replace the NaCl. Again, CaCl₂ and MgCl₂ were added at a level which gave the same proportion of the DVs of these minerals as 0.4% KCl. The highest flavor acceptability in the product with 20% less NaCl was obtained when only citric acid was added as a flavor modifier.     

The role of salt washing of fish skins in chemical and rheological properties of gelatin extracted

Dover sole (Solea vulgaris) skins were washed with different salt solutions previous to gelatin extraction by a mild acid pre-treatment. The effects of NaCl, KCl, MgCl₂, MgSO₄ and no-salt washing on the mineral content, yield of extraction, molecular weight distribution, gel strength, aggregation phenomena and viscoelastic properties of gelatin newly dissolved and after overnight cold maturation were evaluated. Skin washing with NaCl and KCl induced noticeable changes in molecular weight distribution, and consequently in gel strength and rheological properties, especially when compared with unsalted gelatin preparations. However, salts containing Mg²⁺ gave rise to the retaining of this bivalent cation in the resultant gelatin, which is detrimental to the gelatin quality.     

Fermentation profiles of Manzanilla-Aloreña cracked green table olives in different chloride salt mixtures

NaCl plays an important role in table olive processing affecting the flavour and microbiological stability of the final product. However, consumers demand foods low in sodium, which makes necessary to decrease levels of this mineral in fruits. In this work, the effects of diverse mixtures of NaCl, CaCl₂ and KCl on the fermentation profiles of cracked directly brined Manzanilla-Aloreña olives, were studied by means of response surface methodology based in a simplex lattice mixture design with constrains. All salt combinations led to lactic acid processes. The growth of Enterobacteriaceae populations was always limited and partially inhibited by the presence of CaCl₂. Only time to reach half maximum populations and decline rates of yeasts, which were higher as concentrations of NaCl or KCl increased, were affected, and correspondingly modelled, as a function of salt mixtures. However, lactic acid bacteria growth parameters could not be related to initial environmental conditions. They had a longer lag phase, slower growth and higher population levels than yeasts. Overall, the presence of CaCl₂ led to a slower Enterobacteriaceae and lactic acid bacteria growth than the traditional NaCl brine but to higher yeast activity. The presence of CaCl₂ in the fermentation brines also led to higher water activity, lower pH and combined acidity as well as a faster acidification while NaCl and KCl had fairly similar behaviours. Apparently, NaCl may be substituted in diverse proportions with KCl or CaCl₂ without substantially disturbing water activity or the usual fermentation profiles while producing olives with lower salt content.