RESEARCH NOTE THE EFFECTS OF SALTS ON THERMAL TRANSITION CURVES OF COD MUSCLE

Examination of the thermograms of cod muscle to which various salts have been added indicate that NaI decreases transition energies of both myosin and actin as compared to a no salt control, and to NaCl and Na₂SO₄ treated samples. In contrast, CaCl₂ and MgCl₂ increases but broadens the peaks.     

Viscoelasticity of Frozen/Thawed Egg Yolk as Affected by Salts, Sucrose and Glycerol

Based on dynamic rheological measurements, sucrose, glycerol and magnesium chloride (MgCl₂) prevented egg yolk gelation at concentrations of 2% and higher. These additives showed improved cryoprotectant effects as their concentrations were increased. Sodium chloride (NaCl) at higher than 2% also prevented gelation but at 10%, it caused a considerable increase in viscosity of unfrozen yolk. Calcium chloride (CaCl₂) showed an opposite effect, promoting protein coagulation before freezing. Samples with 2% CaCl₂ gelled completely after 36h at -24°C. Before freezing, potassium chloride (KCl) in the range 2–10% had an effect similar to that of NaCl. However, after freezing its effect changed. Yolk with 2% KCl, frozen 36h at -24°C, showed very elastic behavior.     

Proteolysis levels of white cheeses salted and ripened in brines prepared from various salts

This study was carried out to investigate the effects of salting and ripening periods in brines, prepared from various salts, on the properties of white cheeses. The brines were made from a mixture of NaCl with CaCl₂, KCl and MgCl₂ at 1 : 1 (molar basis) ratio. The NaCl solution alone was used as a control. The effects of different brines on total nitrogen, water-soluble nitrogen, nonprotein nitrogen, casein nitrogen and proteose-peptone nitrogen contents of cheeses were found to be insignificant, whereas the effect of ripening period on these properties was found to be significant ( P  < 0.05).     

Formulation Protocol and Dicationic Salts Affect Protein Functionality of Model System Beef Batters

ABSTRACT: The objective of this study was to determine if addition, and order of addition, of CaCl₂ and MgCl₂ affected protein functionality of lean beef preblends. Four treatments were applied to non-preblended (NPB) batters prior to thermal processing. Six treatments were applied to preblended (PB) batters 12 h prior to thermal processing. All treatments contained 2% NaCl. Dicationic salts decreased raw pH in NPB and PB batters, while cooked pH was unaffected. Magnesium chloride in NPB and CaCl₂+ MgCl₂ in PB batters resulted in the highest total soluble protein (TSP). Calcium chloride + MgCl₂ in NPB batters resulted in firmer gels compared to the control. Magnesium chloride, in both NPB and PB, caused the greatest increase in soluble myosin, and preblending decreased myosin solubility.     

MEASURING THE WATER HOLDING CAPACITY OF NATURAL ACTOMYOSIN FROM CHICKEN BREAST MUSCLE IN THE PRESENCE OF PYROPHOSPHATE AND DIVALENT CATIONS

The water holding capacity (WHC) of natural actomyosin (NAM) extracted at pH 9.2 in 0.6M KCl was measured in the presence and absence of various combination of sodium pyrophosphate (PP_i), MgCl₂ and CaCl₂ using a modification of the classical centrifugation technique. Samples, in the presence of 0.15M NaCl and 20 mM sodium phosphate buffer pH 6, were spun at 30,900 X G (as measured at the bottom of the centrifuge tube) for 15 min at 2–4C. The results show that between 17 and 20 g water/g protein were bound over a wide range of NAM concentrations. In each case the amount of water held by the experimental sample was equal to or less than the amount held by a control run at the same time: 5 mM PP_i= 100%; 5 mM PP_i+ 5 mM MgCl₂= 58%; 5 mM MgCl₂= 85%; 5 mM PP_i+ 5 mM CaCl₂= 68% and 5 mM CaCl₂= 92% of the control. Thus polyphosphate addition in the presence of divalent cations lowers the WHC of NAM. The absence of the organized structure of muscle in NAM is postulated to be the reason that polyphosphate plus divalent cation reduced WHC in these samples. A series of preliminary experiments were run in order to determine the effect of experimental parameters on WHC.     

Effect of the addition of trisodium citrate and calcium chloride during salting on the rheological and textural properties of Cheddar-style cheese during ripening

The effect of addition of trisodium citrate (TSC) and calcium chloride (CaCl₂) on the textural and rheological properties of Cheddar-style cheese was investigated. Cheese curds were salted (2.5%) with NaCl (control) or NaCl supplemented with either TSC or CaCl₂ with a constant ionic strength. Casein-bound calcium phosphate decreased upon addition of TSC and increased upon addition of CaCl₂. Addition of CaCl₂ resulted in increased hardness. Addition of TSC resulted in reduced hardness but more elastic cheeses at high temperatures. The addition of TSC or CaCl₂ at salting had a significant effect on cheese rheology and texture.     

Characterisation of soybean glycinin and β-conglycinin fractionated by using MgCl2 instead of CaCl2

A simple two step precipitation method was used to investigate the effect of MgCl₂ instead of CaCl₂ on fractionation of soybean glycinin and β-conglycinin. Compositional and physicochemical properties of the resulting protein fractions were characterised. The optimised procedure, in terms of protein yield, purity, phytate content and physicochemical properties, was obtained when the addition of 5 m m MgCl₂ was used. After application of 5 m m MgCl₂, the phytate content of the glycinin-rich and β-conglycinin-rich fractions was about 0.4% and 1.3%, respectively, but the addition of 5 m m CaCl₂ increased the phytate content of the glycinin-rich fraction to 1.25% and decreased that of β-conglycinin-rich fraction to 0.67%. Low phytate protein product was suitable for use in infant formula and acidic food. The solubility of the glycinin-rich fractions with MgCl₂ was significantly higher than that with CaCl₂ at pH < 4.5. Application of MgCl₂ improved thermal stability of the β-conglycinin-rich fraction.     

EFFECT OF SLURRY PREPARATION METHODS ON THE RHEOLOGICAL AND GELLING BEHAVIOR OF SOY PROTEIN

The order of addition of solutes and soy protein during the preparation of slurries influenced rheological behavior of unheated and heated slurries. The effect of the order of addition of glucose, sucrose and Na₂HPO₄ into the slurries was small with respect to the influence of the order of addition of CaCl₂ and NaCl. The effectiveness of salts in reducing apparent viscosity of both unheated and heated slurries was greater than that of glucose and sucrose. Na₂HPO₄ was the more effective salt in reducing viscosity followed by NaCl and CaCl₂. When salts were added, an inverse relationship was obtained between viscosity and water-holding capacity of gelled soy protein slurries.     

Nondestructive Analysis of Salt, Water, and Protein in Dried Salted Cod using Computed Tomography

ABSTRACT:  Computed X-ray tomography (CT) was used to determine NaCl, water, and protein levels in dried salted cod. Cod fillets were salted and dried, and CT was conducted several times during the process. Also, homogenized cod samples with a chemical composition covering the typical composition of cod during salting and drying were produced, and CT scanned. Chemical composition of fillet and model samples was predicted from CT images acquired at 80, 110, and 130 kV. The best average prediction errors (RMSECV) obtained for homogenized samples were 0.6% NaCl, 1.3% water, and 1.5% protein; all explained variances were R ²= 0.99 or above. The best RMSECVs and explained variances for cod fillet samples were 0.9% NaCl ( R ²= 0.96), 0.8% water ( R ²= 0.99), and 1.4% protein ( R ²= 0.79). Combining CT values from 2 or 3 voltages gave the best predictions except when predicting salt in cod fillet, where 1 voltage was sufficient.     

Factors Determining Yield Stress and Overrun of Whey Protein Foams

ABSTRACT: Foams were formed by whipping whey protein solutions (15% w/v protein) containing NaCl, CaCl₂, lactose, or glycine. Foam overrun and yield stress were determined. Foams made from whey protein ingredients have greater overrun and yield stress if the concentration of β-lactoglobulin is high relative to a-lactalbumin. The presence of 0.4 M CaCl₂ in the foaming solution increases overrun and yield stress for β-lactoglobulin and a-lactalbumin. The high yield stress of β-lactoglobulin and a-lactalbumin foams made from solutions containing CaCl₂ suggests that CaCl₂ is altering rheological properties of the interfacial protein film and/or contributing to protein aggregation or network formation in the lamellae.     

Effect of CaCl2 and KCl on Physiochemical Properties of Model Nutritional Beverages Based on Whey Protein Stabilized Oil-in-Water Emulsions

ABSTRACT: Calcium chloride (0 to 10 mM) and potassium chloride (0 to 600 mM) were added into model nutritional beverage emulsions containing 7% (w/w) soybean oil droplets and 0.35% (w/w) whey protein isolate (pH 6.7). The particle size, surface charge, viscosity, and creaming stability of the emulsions then were measured. The surface charge decreased with increasing mineral ion concentration. The particle size, viscosity, and creaming instability of the emulsions increased appreciably above critical CaCl₂ (3 mM) and KCl (200 mM) concentrations because of droplet flocculation. The origin of this effect was attributed to reduction of the electrostatic repulsion between droplets due to electrostatic screening and ion binding. CaCl₂ promoted emulsion instability more efficiently than KCl because Ca²⁺ ions are more effective at reducing electrostatic repulsion than K⁺ ions.     

Modeling of Calcium Chloride and Pectin Methylesterase Prefreezing Treatments of Strawberries and Jams

ABSTRACT: :
Different calcium chloride (CaCl₂) and pectin methylesterase (PME) prefreezing treatments in a vacuum were used to clarify the most effective prefreezing factors for strawberries and traditional jams. Fractional factorial design and modeling were used. CaCl₂ had the greatest effect on the majority of the 15 studied responses ( p < 0.001). The pretreatment time should be short (about 5 to 10 min), the temperature low (less than 20 °C), the vacuum level high (pressure less than 10 kPa), the CaCl₂ concentration moderate (about 1%) and the dosage of PME comparatively low (about 50 to 100 nkat/g) in order to yield high quality frozen strawberries for jam making.     

Effect of water hardness on cooking characteristics of cowpea (Vigna unguiculata L. Walp) seeds

Cowpeas were cooked in water made hard (or soft) by the separate addition of similar concentrations of certain salts (CaCl₂, MgCl₂, or NaHCO₃). The beans were also cooked in hard tap water and in double distilled water before and after soaking in water. Hard water caused a significant decrease in softness, led to reduced water absorption, and also decreased solids loss in the cooked product, but it increased the cooking time and discolouration of the beans. Hard water also gave rise to a significant ( P <0.05) increase in mineral content, but it had less effect on the proximate composition of the cooked products.     

Fractionating Soybean Storage Proteins Using Ca2+ and NaHSO3

ABSTRACT:  Individual soybean storage proteins have been identified as having nutraceutical properties, especially β-conglycinin. Several methods to fractionate soy proteins on industrial scales have been published, but there are no commercial products of fractionated soy proteins. The present study addresses this problem by using calcium salts to achieve glycinin-rich and β-conglycinin-rich fractions in high yields and purities. A well-known 3-step fractionation procedure that uses SO_2, NaCl, and pH adjustments was evaluated with CaCl₂ as a substitute for NaCl. Calcium was effective in precipitating residual glycinin, after precipitating a glycinin-rich fraction, into an intermediate fraction at 5 to 10 mM CaCl₂ and pH 6.4, eliminating the contaminant glycinin from the β-conglycinin-rich fraction. Purities of 100%β-conglycinin with unique subunit compositions were obtained after prior precipitation of the glycinin-rich and intermediate fractions. The use of 5 mM SO₂ in combination with 5 mM CaCl₂ in a 2-step fractionation procedure produced the highest purities in the glycinin-rich (85.2%) and β-conglycinin-rich (80.9%) fractions. The glycinin in the glycinin-rich fraction had a unique acidic (62.6%) to basic (37.4%) subunit distribution. The β-conglycinin-rich fraction was approximately evenly distributed among the β-conglycinin subunits (30.9%, 35.8%, and 33.3%, for α', α, and β subunits, respectively). Solids yields and protein yields, as well as purities and subunit compositions, were highly affected by pH and SO₂ and CaCl₂ concentrations.     

Formation of Soy Protein Isolate Cold-set Gels: Protein and Salt Effects

ABSTRACT: The influence of protein and calcium concentration on soy protein cold-set gel formation and rheology has been investigated. Cold-set gels can be formed at soy protein concentrations from 6% to 9% and calcium concentrations from 10 to 20 mM. Gel properties can be modulated by changing the protein and/or CaCl₂ concentrations. An increase in CaCl₂ concentration from 10 to 20 mM increased gel opacity while an increase in protein concentration from 6% to 9% decreased opacity. Water-holding capacity improved with increasing protein concentration and decreasing CaCl₂ concentration. The elastic modulus (G') increased with protein and calcium chloride concentrations. Microscopy revealed an increase in the diameters of aggregates and pores as CaCl₂ concentration increased and as protein concentration decreased. Cold-set gels with a broad range of characteristics can be obtained from soy protein.     

Effects of natural (or seasonal) variation in concentration of components of milk and addition of divalent cations on UHT processing characteristics

Interrelationships in composition of milk, ultra-high temperature processing behaviour and weight and composition of deposits were investigated using bulked milks collected and processed at intervals over a one year period. The only statistically significant correlations of efficient run time with components of the milk were with concentrations of Mg and casein. In a separate experiment 0.62-4.1 mM MgCl₂ was added to milk before processing. This gave rise to a large reduction in the processing time as predicted by this correlation. The addition of 0.375-2.5 mM CaCl₂ gave comparable reductions in run time.     

Influence of CaCl2 and NaCl injections on the texture and flavour of beef

The present study compares the effects of pre− and post-rigor injections of 0.1 m CaCl₂ or 0.15 m NaCl on sensory characteristics (appearance, texture and flavour) and on physical measurements (sarcomere length, drip loss and mechanical resistance of raw myofibres) of beef meat at 2, 6 and 14 days of ageing. An injection of CaCl₂ 1 h post-mortem (pH ≈6.8) greatly decreased sarcomere length and myofibrillar resistance, increased drip loss, contracted appearance and brightness, and induced abnormal flavour, mainly bitterness, whatever the ageing time. CaCl₂-treatment 1 h post-mortem produced little effect on tenderness during ageing; it was slightly higher at day 2 and lower at day 14 than controls. CaCl₂-injection at 24 h post-mortem did not change the sarcomere length but produced a smaller increase in drip loss and a decrease in the resistance of raw myofibres. Improved meat tenderness compared to controls occurred mainly at days 2 and 6 but, during ageing, abnormal flavour appeared by day 6. NaCl-injection had no effect on either sarcomere length or resistance of raw myofibres, but produced higher drip loss and saltier taste at day 14 only. Thus pre-rigor injection of CaCl₂ is not recommended because of adverse effects on flavour and appearance of meat. Post-rigor injection of CaCl₂ has a beneficial effect on tenderness in the first part of the ageing period, but after complete ageing, the only overall benefit is a decrease in the variability between animals.     

Methods to Detect the Occurrence of Various Indicator Bacteria on the Surface of Retail Poultry in Spain

ABSTRACT: Contamination levels (cfu/g and cfu/cm²) of indicator microorganisms in retail broiler chicken carcasses in León (Spain) were investigated. Counts (log₁₀ cfu/g) were 5.19, 3.04, 2.73, 3.38, and 3.16 for total aerobic counts ( TAC), Enterobacteriaceae , coliforms determined by the standard VRBA method (coliforms-VRBA), coliforms determined by the Hydrophobic Grid Membrane Filter method (coliforms-HGMF), and Escherichia coli (HGMF method), respectively. These values fit into the microbiological criteria for poultry meat consulted. A low correlation coefficient was found between TAC and Enterobacteriaceae counts (r = 0.308; P = 0.053) and between coliforms-VRBA and coliforms-HGMF counts ( r = 0.398; P = 0.048). The determination method had a significant influence on the coliform counts obtained. All broiler chicken carcasses harbored E. coli biotype I. E. coli biotype II was detected in 20% of the samples. The HGMF method was not completely specific for detecting E. coli since 11.25% of false positive colonies were found.     

Characterization of honey amylase

ABSTRACT:  The major α-amylase in honey was characterized. The optimum pH range and temperature were determined for the enzyme as 4.6 to 5.3 and 55 °C, respectively. The enzyme was stable at pH values from 7 to 8. The half-lives of the purified enzyme at different temperatures were determined. The activation energy for heat inactivation of honey amylase was 114.6 kJ/mol. The enzyme exhibited Michaelis–Menten kinetics with soluble starch and gave K _M and V _max values of 0.72 mg/mL and 0.018 units/mL, respectively. The enzyme was inhibited by CuCl (34.3%), MgCl₂ (22.4%), and HgCl₂ (13.4%), while CaCl₂, MnCl₂, and ZnSO₄ did not have any effect. Starch had a protective effect on thermal stability of honey amylase. Therefore, it might be critical to process or control the amylase in honey before incorporation into starch-containing foods to aid in the preservation of starch functionality. One step could involve heat treating honey with other ingredients, especially those that dilute and acidify the honey environment.     

The effect of brine composition and pH on the yield and nature of water-soluble proteins extractable from brined muscle of cod (Gadus morhua)

Fillets of Atlantic cod (Gadus morhua) were held for 36 h in brines of pH 6.5 and 8.5, respectively, containing various combinations of NaCl, KCl, MgCl₂ and CaCl₂. Proximate analyses and chloride content were determined. Soluble muscle protein extracted in distilled water and protein released into the brine following salting was determined by SDS–PAGE. The soluble fraction was not affected by the presence of divalent salts or KCl in the brines, but it was affected by the initial pH. Both actin and myosin heavy chain (MHC) were released in pH 6.5 brines after immersion of the fish. On the other hand, an initial pH of 8.5 did not favour the release of these proteins. There was a smaller variety of remaining soluble proteins in salted muscle with an initial pH of 6.5, than with 8.5. However, this effect of the lower pH was offset to the extent that the ionic strength of the brine was higher.