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.     

Storage of common mushroom under controlled atmospheres

The effect of controlled atmosphere (CA) on the shelf-life of the common mushroom ( Agaricus bisporus ) was assessed using six parameters correlated with its commerical qualities. Low CO₂ concentrations (up to 2.5%) reduced brown discolouration compared to the control in air. Higher CO₂ concentrations enhanced both internal and external browning. Low O₂ concentrations reduced growth of micro-organisms, including pseudomonads. Respiration rate, when the mushrooms are placed again in normal air, is proportional to CO₂ concentration during storage suggesting that CO₂ exhibits a phytotoxic effect on mushrooms. A lower mannitol content was noted in mushrooms stored under CA than those stored in air (control). Mushrooms stored in a 5% CO₂ atmosphere for 7 days did not break their veil but their texture was very soft and spongy. Texture losses decreased when CO₂ concentrations increased.     

Structure and Composition of Mushrooms as Affected by Hydrogen Peroxide Wash

An experimental H₂O₂/browning inhibitor wash treatment and its effect on mushroom structure and composition were studied. Experimentally washed mushrooms ( Agaricus bisporus ) were compared with conventionally washed mushrooms and untreated controls. Examination by scanning electron microscopy showed damage to hyphae producing a matted appearance at the pileus surface with both experimental and conventional washed samples. Mushrooms after the experimental wash had an elevated sodium content from the sodium erythorbate browning inhibitor but contained no H₂O₂ residue. In pileus tissue, soluble phenol levels were higher and the content of free amino acids was lower in mushrooms after the experimental wash. No other notable compositional differences or adverse effects of treatment on quality were found.     

Shelf-Life Extension of Fresh Mushrooms (Agaricus bisporus) By Application of Hydrogen Peroxide and Browning Inhibitors

ABSTRACT: An experimental washing process for fresh mushrooms entailing immersion in 5% H₂O₂, followed by application of a sodium erythorbate-based browning inhibitor, was optimized, scaled up, and made continuous. The laboratory process described previously was modified by adding a pre-wash step using 0.5% to 1% H₂O₂, increasing the wash solution H₂O₂ concentration from 3% to 5%, and substituting 4% sodium erythorbate + 0.1% NaCl for the more complex browning inhibitor formulation used previously. A continuous, commercial-scale washing facility was built to test the new process. Mushrooms washed by this process were free of adhering soil, less subject to brown blotch than conventionally washed mushrooms, and at least as resistant to enzymatic browning as unwashed mushrooms during storage at 4 °C. Storage at 10 °C accelerated development of brown blotch and browning.     

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.     

Improved Firmness in Calcified Diced Tomatoes by Temperature Activation of Pectin Methylesterase

ABSTRACT: The effects of temperature and calcium on pectin methylesterase (PME) activity and texture in tomato pericarp material were examined. Heating thin slices of pericarp to temperatures between 50°C and 75°C led to the rapid evolution of methanol from the material, indicating an activation of PME. This activity was further stimulated when CaCl₂ (up to 2.0% w/v) was added. When applied to half-inch diced tomato pericarp, the same conditions that led to the activation of PME also improved firmness. Diced tomatoes treated for 5 min with 0.5% CaCl₂ at 70°C were 2.5 times firmer than diced tomatoes treated with CaCl₂ at room temperature. This improvement in texture by treating with CaCl₂ at elevated temperatures was only apparent when the tomatoes received a subsequent 100°C treatment. Heating tomatoes to 70°C either before or after the CaCl₂ treatment also improved firmness through a subsequent high-temperature treatment, but to a lesser extent than heating during the CaCl₂ treatment. These results are consistent with the model that heating to 70°C greatly increases PME activity, leading to extensive pectin de-esterification and increased calcium cross-linking of the pectins in the middle lamella. Production of thermally processed diced tomatoes with improved firmness should be possible by increasing the temperature during and after calcium treatment.     

Effect of some thermal and chemical pre-treatments on smoked oyster mushroom quality

The effect of different thermal and chemical pre-treatments on quality and enzyme activities of smoked mushroom was investigated. Mushrooms were blanched (water and steam) and dipped in different concentrations of SO₂, H₂O₂, ethylenediaminetetraacetic acid (EDTA) and citric acid for 10 min before smoking. Enzyme activities, colour characteristics, microbiological and sensory examinations were carried out every 2 weeks up to 8 weeks of storage at 4 °C. Smoked mushroom pre-treated with sulphites (SO₂), H₂O₂ and steam blanching had the best colour values, better scores for all sensory characteristics and lower non-enzymatic browning compared with the other pre-treatments. Pre-treatment against total aerobic bacteria, yeast and moulds was the most effective when using citric acid, EDTA and steam, followed by smoking of mushroom. The most effective pre-treatments on quality and safety of smoked mushrooms were those using H₂O₂ and steam. It can be concluded that thermal and chemical treatments followed by smoking of mushroom reduce enzyme activities and are suitable for preserving mushrooms.     

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.     

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.     

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.     

CALCIUM CHLORIDE EFFECTS ON TBA VALUES OF COOKED MEAT

Ground chicken breast and beef top round (semimembranosus) muscles were treated with CaCl₂ (0.05, 0.10, 0.15, and 0.20% on final sample weight basis) and cooked to an internal temperature of 80C. Cooked samples were aerobically stored at 4C for 0 or 4 days and analyzed for 2-thiobarbituric acid (TBA)-reactive substances. Results indicated that CaCl₂ can either inhibit or accelerate lipid oxidation in cooked meat depending on its concentration/meat animal species. TBA values of chicken samples were decreased by CaCl₂ used at ≥ 0.1% of final weight. However, only beef samples treated with the highest CaCl₂ level (0.20%) tended to have lower TBA values when compared to control samples (treated with deionized water only). CaCl₂ used at low levels (0.05% for chicken and ≤0.15% for beef) tended to elevate cooked meat TBA values.     

Texture of rehydrated dried bell peppers modified by low-temperature blanching and calcium addition

Diced green bell pepper was blanched twice, once at 51–79 °C for 19–61 min, and once at 95 °C for 3 min, and dried. The firmness of rehydrated samples was measured by puncture, and optimum conditions assessed by response surface methodology. The optimized model showed that, blanching at 65 °C for 49 min gave a 64% increase in puncture force over the control. The optimum temperature was used to evaluate the effect of adding CaCl₂. The dices were blanched twice, once at 65 °C for 3 min in either 0 or 4% CaCl₂, secondly in either 0 or 2% CaCl₂ solution at 95 °C for 3 min. In the second case the dices had been held at room temperature for 0–30 min before treatment. Adding CaCl₂ increased puncture force significantly ( P  ≤ 0.05). The best results, those which gave greatest firmness, were obtained by blanching at 65 °C for 3 min in 4% CaCl₂, holding for 16 min after blanching, followed by a secondary blanching at 95 °C in 2% CaCl₂.     

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.     

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.     

Incorporation of Soymilk Lipid into Soy Protein Coagulum by the Addition of Calcium Chloride

ABSTRACT: The effect of protein composition on the lipid incorporation into protein coagulum (tofu curd) was investigated using soymilk prepared from mixtures of glycinin-rich and β-conglycinin-rich soybeans. The lipid incorporation takes place with the addition of CaCl₂ so that a particulate fraction of the protein is aggregated. The incorporation occurred by less addition of CaCl₂ with increasing glycinin in soymilk. The protein particle content and the glycinin content of the particles increased along with increasing glycinin. The lipid incorporation took place at lower CaCl₂ concentration when the particulate glycinin content was high. The mechanism of the lipid incorporation into soybean curd is discussed from these results.     

Postmortem Calcium Chloride Injection Alters Ultrastructure and Improves Tenderness of Mature Chinese Yellow Cattle Longissimus Muscle

ABSTRACT: This study was conducted to test the hypothesis that postmortem calcium injection could activate the calpain system in mature Chinese Yellow Cattle muscle, thereby promoting meat tenderization through disruption of the myofibril structure during aging. A 10% (w/w) injection of CaCl₂ (300 m M ) solution lowered the Warner-Bratzler shear values of longissimus muscle by more than 30% ( P < 0.05), even with only 24 h postmortem storage when compared with noninjected or water-injected controls. The accelerated meat tenderization by the Ca²⁺ treatment paralleled the changes in myofibril fragmentation index and fracture of the myofibril ultrastructure throughout the sarcomere but most notably around the I-bands and the Z-disks. Injection of ZnCl₂ (50 m M ) largely inhibited these proteolytic changes. The colorimetric L * and a * values were not affected by CaCl₂ nor by ZnCl₂ injection. The results suggest that postmortem CaCl₂ injection can be used to help resolve the toughness problem of mature Chinese Yellow Cattle meat and shorten the aging time required to achieve adequate tenderness.     

Ultrastructural and Changes in Pectin Composition of Sweet Cherry from the Application of Prefreezing Treatments

ABSTRACT: Thermal and calcium pretreatments applied to preserve the sweet cherry texture by the freezing/thawing process produced biochemical changes in the pectic substances and ultrastructural alterations to the cells and tissues, which were visible under scanning electron microscopy. Partial dehydration of the epidermic tissue caused by calcium (100 m M CaCl₂) and thermal (50 °C/10 min) pretreatment attenuated the surface damage produced by freezing. However, pretreatment at 70 °C/2 min caused partial destruction of the epidermic tissue and plasmolysis of the parenchymatic cells. After freezing, the cell walls in the parenchymatic tissue of the fruits pretreated with 100 m M CaCl₂ exhibited swelling as a result of gelling of the cell-wall pectic material. Thermal pretreatments increased the ethylenediaminetetraacetic acid (EDTA)-soluble pectin fraction and reduced the degree of pectin esterification. Thermal treatments at 70 °C, without immersion in calcium, reduced the water- and pectinase-soluble pectin fractions, whereas immersion in calcium prevented depolymerization of these fractions. Immersion in 100 m M CaCl₂ increased the water-soluble pectin fraction.     

Effects of Hot Rehydration in the Presence of Hydrogen Peroxide on Microbial Quality, Texture, Color, and Antioxidant Activity of Cold-stored Intermediate-moisture Sun-dried Figs

ABSTRACT: Pectin methylesterase (PME) causes considerable softening in intermediate-moisture (IM) figs rehydrated at 30°C and cold stored at 28% to 29% moisture content. Rehydration of figs at 80°C for 16 min inactivated PME partially (25–30%), but this did not prevent the softening over 3 mo of cold storage. Also, heating did not reduce the microbial load of figs significantly and increased their browning. In contrast, rehydration of figs 1st in 2.5% H₂O₂ at 80°C for 8 min and then in water at 80°C for 8 min reduced the microbial load of IM figs significantly, turned their brown color to yellow-light brown, and maintained their desired textural properties. The residual H₂O₂ in IM figs decomposed in 3 or 1.5 wk by the in situ catalase or by application of the iron (II) sulfate-ascorbic acid residue elimination method, respectively. Hot rehydration did not affect the antioxidant activity of IM figs, but treatment of figs with H₂O₂ increased their antioxidant activity slightly. These results indicate that the hot rehydration of figs in the presence of H₂O₂ and cold storage may be applied to obtain safe and SO₂-free light-colored IM fig products.     

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.     

Role of sorbic acid in nonenzymic browning reactions in liquid and solid model food systems

Role of sorbic acid (SA) in browning development in model systems has been studied. In liquid model systems containing water-glycerol-glucose (WGG), water-glycerol-sucrose (WGS), 45% sucrose and 30% sucrose plus 15% glucose, SA degraded when stored at 37°C forming brown pigments. Addition of amino acids (glycine or lysine monohydrochloride) increased the rate of browning development while Cu²⁺ reduced SA degradation and browning development. In the absence of amino acids and SA, WGG and WGS systems did not brown appreciably.
In solid systems with SA adsorbed on microcrystalline cellulose, the maximum rate of browning occurred at 0.73 a_w , but maximum rate of SA loss was at 1.0 a_w . In all systems inclusion of amino acids reduced SA degradation but increased browning development. The rate of SA-induced browning was considerably higher than that caused by sugar-amino acid interactions.