Effect of partial substitution of complex phosphates with sodium bicarbonate on aggregation, conformation and gel properties of beef-pork-chicken complex myofibrillar proteins

BACKGROUND

Complex phosphates (CP) can improve the physicochemical properties and gelation properties of myofibrillar fibrous protein (MP) in mixed meat products, but an excessive intake of phosphates over a long period of time is harmful to health. The present study investigated the effects of partial or complete substitution of CP with sodium bicarbonate (SB) on the physicochemical properties and gel properties of beef-pork-chicken mixed myofibrillar protein (BPC-MP), aiming to evaluate the feasibility of this method in reducing the amount of phosphate in mixed meat products.

RESULTS

Under the optimal substitution conditions, the turbidity of BPC-MP was reduced by 37.8%, the net negative potential was increased by 28.9% and the modulus of elasticity (G') was increased. The tertiary structure indexes of protein (including fluorescence intensity, surface hydrophobicity and active thiol content) were significantly changed, whereas the α-helix and β-turn angle contents in the secondary structure of protein were significantly increased. In addition, the water retention ability and strength of gel were also improved, which were increased by 20.7% and 42.6%, respectively. The results of scanning electron microscopy showed that the SB substitution group had a more compact and ordered microstructure.

CONCLUSION

The results showed that partial substitution of CP with SB reduced the amount of phosphate added to BPC-MP and had a positive effect on the physicochemical and gel properties of BPC-MP. © 2024 Society of Chemical Industry.

Utilizing the pH-Shift Method for Isolation and Nutritional Characterization of Mantis Shrimp (Oratosquilla nepa) Protein: A Strategy for Developing Value-Added Ingredients

This study focused on the production of protein isolates from mantis shrimp (MS). The pH-shift method was investigated to understand its impact on the protein yield, quality, and properties of the produced isolates. The first step was determining how the pH affected the protein solubility profile, zeta potential, and brown discoloration. The pH-shift process was then established based on the maximum and minimum protein solubilization. The solubilization pH had a significant impact on the mass yield and color of the produced protein, with a pH of 1.0 producing the maximum mass in the acidic region, whereas a maximum was found at a pH of 12.0 in the alkaline region (p < 0.05). Both approaches yielded mantis shrimp protein isolates (MPIs) with precipitation at a pH of 4.0 and a mass yield of around 25% (dw). The TCA-soluble peptide and TBARS levels were significantly lower in the MPI samples compared to MS raw material (p < 0.05). The MPIs maintained essential amino acid index (EAAI) values greater than 90%, indicating a high protein quality, and the pH-shift procedure had no negative impact on the protein quality, as indicated by comparable EAAI values between the mantis shrimp protein isolate extract acid (MPI-Ac), mantis shrimp protein isolate extract alkaline (MPI-Al), and MS raw material. Overall, the pH-shift approach effectively produced protein isolates with favorable quality and nutritional attributes.

A novel approach to measure carbonate alkalinity in aqueous solutions using a total organic carbon analyzer

Carbonate alkalinity is crucial in regulating the pH and buffering capacity of natural water systems. Thus, its accurate measurement is essential to understand various water environments that affect water quality and ecosystem health. However, conventional potentiometric titration has some limitations. It results in inaccurate measurements of carbonate alkalinity when the alkalinity levels are low or when high dissolved organic matter or inorganic ion levels exist. Herein, we propose a novel approach to accurately measure carbonate alkalinity using a total organic carbon (TOC) analyzer. An extensive study comparing the accuracy and reliability of the conventional potentiometric titration method with those of the newly developed TOC method was conducted to develop and verify highly accurate measurements of carbonate alkalinity. The TOC method has several advantages over the conventional potentiometric titration methods, such as its ability to accurately measure carbonate alkalinity in the presence of high dissolved organic matter or inorganic ion levels and its ability to provide rapid and automated measurements with high reproducibility. Because, the limit of detection, limit of quantification, and the variation coefficient of the measurements was 0.016 mM (0.2 mgC/L), 0.050 mM (0.6 mgC/L), and 3.68 % respectively. Thus, the development of a novel TOC method has significant environmental implications as it provides a reliable and accurate means to measure carbonate alkalinity in solutions containing various organic matter types.

Monosaccharide-induced glycation enhances gelation and physicochemical properties of myofibrillar protein from oyster (Crassostrea gigas)

Glycation offers a promising potential to improve protein gelling properties in food industries. Therefore, the study was aimed to illustrate the effect of five monosaccharides (erythrose-aldotetrose, xylose-aldopentose, glucose-aldohexose, galactose-aldohexose, and fructose-ketohexose) with different carbon numbers and structure on the structure-gelling relationship of myofibrillar protein (MP) from oyster (Crassostrea gigas). Results showed that monosaccharides significantly increased the glycation degree of MP by increasing sulfhydryl content, forming stable tertiary conformation and decreasing surface hydrophobicity. Moreover, the gel properties of MP like gel strength, water holding capacity, water mobility were improved by alleviating aggregation including the increase of solubility and the decrease of particle sizes. Oyster MP glycated by glucose (aldohexose) possessed the optimal gel properties. Molecular docking simulation showed that hydrogen bonds and hydrocarbon bonds were the mainly non-covalent binding modes. The study will provide a theoretical basis for oyster protein glycation and expand its application on food gel.

Additive Effects of L-Arginine with Potassium Carbonate on the Quality Profile Promotion of Phosphate-Free Frankfurters

The present study investigated the additive effects of L-Arginine (L-Arg) with potassium carbonate (PC) on the quality characteristics of phosphate-free frankfurters. The results showed that L-Arg combined with PC could act as a viable phosphate replacer by decreasing cooking loss and improving the textural properties of phosphate-free frankfurters (p < 0.05), mainly because of its pH-raising ability. Moreover, L-Arg could assist PC in effectively retarding lipid oxidation in phosphate-free frankfurters during storage (p < 0.05). Furthermore, 0.1% L-Arg combined with 0.15% PC was found to exhibit the best optimal phosphate-replacing effect. This combination could also overcome quality defects and promote the sensory attributes of phosphate-free frankfurters to the maximum extent. Therefore, our results suggest that L-Arg combined with PC can be considered a feasible alternative for the processing of phosphate-free frankfurters with an improved quality profile and superior health benefits.

Effect of Ultrasound-Assisted Sodium Bicarbonate Treatment on Aggregation and Conformation of Reduced-Salt Pork Myofibrillar Protein

To study the effects of an ultrasound (0, 30, and 60 min) and sodium bicarbonate (0% and 0.2%) combination on the reduced-salt pork myofibrillar protein, the changes in pH, turbidity, aggregation, and conformation were investigated. After the ultrasound-assisted sodium bicarbonate treatment, the pH increased by 0.80 units, the absolute value of Zeta potential, hydrophobic force, and active sulfhydryl group significantly increased (p < 0.05), and the turbidity and particle size significantly decreased (p < 0.05). Meanwhile, the fluorescence intensity decreased from 894 to 623, and the fluorescence peak showed a significant redshift, which indicated that the ultrasound-assisted sodium bicarbonate treatment exposed the non-polarity of the microenvironment in which the fluorescence emission group was located, leading to the microenvironment and protein structure of myofibrillar tryptophan being changed. Overall, an ultrasound-assisted sodium bicarbonate treatment could significantly improve pork myofibrillar protein solubility and change the protein structure under a reduced-salt environment.

Effect of sodium bicarbonate on textural properties and acceptability of gel from unwashed Asian sea bass mince

Asian sea bass mince gels having different adjusted moisture/water content (80 and 85%; w/w) were prepared with addition of sodium bicarbonate (SB) at various concentrations (0, 0.05 and 0.1%; w/w). Fish mince gels of 80% water content added with 0.05 and 0.1% SB (G80-0.05 and G80-0.1, respectively) had the highest increase (135-139%) in breaking force (BrF) than the respective control gel (G80) (P < 0.05). For gel with 85% water content, a lower increase (17-28%) in BrF was found with the addition of SB as compared to their corresponding control (G85). Whiteness of all samples was continuously decreased with increasing amount of SB, however the water holding capacity was increased drastically with augmenting levels of SB, regardless of the water content (P < 0.05). A loss in the elasticity of gel was attained with the addition of SB as indicated by decreasing storage modulus. A finer and more compact network was detected in a gel containing SB, irrespective of water content. Based on sensory scores, gel having 85% water content added with 0.05 and 0.1% SB had similar acceptability to the control gel (G80) containing 80% water content (commercial level). Therefore, SB at the appropriate level could improve the gelling properties with higher water holding ability of the mince gel with high acceptability.

Effects of different phosphorus-free water-retaining agents on the quality of frozen tilapia fillets

Tilapia is an economically important fish worldwide, but its quality is affected by storage practices. To improve the quality of tilapia fillets during frozen storage, we examined the effect of pretreatment with various combinations of different concentrations of trehalose, potassium bicarbonate, and chitosan. Following pretreatment, we analyzed the tilapia fillets using quality indicators, including soaking weight gain, coating weight gain, water-holding capacity, thawing loss, pH, Ca2+-ATPase activity, and texture characteristics. Water distribution was analyzed using low-field nuclear magnetic resonance and the optimal combination of water-retaining agents was obtained using an L8(27) orthogonal experiment. The results showed that trehalose, potassium bicarbonate, and chitosan improved fillet quality at pretreatment concentrations of 5%-8%, 1.0%, and 0.5%, respectively. The optimal combination was 4% trehalose plus 1.2% potassium bicarbonate plus 0.2% chitosan. The Ca2+-ATPase activity and mastication property of the frozen fillets that were pretreated with the optimized formulation were 1.39 μmol Pi/mg protein·h and 8.55 mJ, respectively, which were 43.3% and 80.0% greater, respectively, than that of the control group. Using a suitable concentration and combination of water-retaining agents cannot only lock-in the internal water content of frozen tilapia fillets but also improve their quality during frozen storage. These results can inform practical storage practices of similar aquatic products.

Improving the Quality of Frozen Fillets of Semi-Dried Gourami Fish (Trichogaster pectoralis) by Using Sorbitol and Citric Acid

Semi-dried gourami fish (Trichogaster pectoralis) is popularly consumed domestically and exported as a frozen product. This study was conducted to prevent deterioration quality in frozen fish fillets during storage. This research aims to investigate the effects of sorbitol and citric acid at concentrations of 2.5% and 5% (w/w) of frozen gourami fish fillets compared to the fillets soaked in distilled water on physicochemical properties, such as cooking loss, cooking yield, drip loss, pH, TBARS, color, and texture profile analyses (TPA) during storage at -18 ± 2 °C for a period of 0, 20, and 40 days. The fish soaked in sorbitol and citric acid solutions had significantly (p < 0.05) higher protein and fat contents than the control sample. Sorbitol was able to retain moisture in the product; therefore, the drip loss and cooking loss were the lowest, and cooking yield was the highest among other samples (p < 0.05). The addition of 5% (w/v) citric acid in frozen fish fillets can significantly retard the thiobarbituric acid reactive substance (TBARS) (p < 0.05) during storage when compared to fish soaked in sorbitol solution kept for the same period. However, the addition of citric acid resulted in low quality in texture and color of frozen fish fillets. The use of sorbitol was the best alternative in frozen fish fillet product due to reducing the negative effects of freezing quality of the products and generating a cryoprotective effect compared to the fillets soaked in distilled water.

Effect of sodium bicarbonate and sodium chloride on aggregation and conformation of pork myofibrillar protein

To investigate the effect of sodium bicarbonate instead of sodium chloride, the changes in pH, turbidity, aggregation, and conformation of myofibrillar protein solution with various amounts of sodium chloride and sodium bicarbonate were studied. When the sodium bicarbonate was increased from 0% to 0.4%, accompanied by the sodium chloride being decreased from 2.0% to 0.8%, the pH increased about 1.20 unites; the absolute values of the Zeta potential, active sulfhydryl, and surface hydrophobicity increased significantly (p < 0.05); and the turbidity, particle size, and Ca²⁺-ATPase activity decreased significantly (p < 0.05). In addition, the Mg²⁺-ATPase activity was not significantly different (p > 0.05) when increasing sodium bicarbonate, implying that sodium bicarbonate did not affect the actin. Overall, the results indicated that an increase in sodium bicarbonate could improve solubility, expose more hydrophobic residues and sulfhydryl groups, and induce Ca²⁺-ATPase inactivation and protein unfolding, leading the myofibrillar protein to denaturation easily.

Comparative stability-indicating chromatographic methods for determination of 4-hexylresorcinol in pharmaceutical formulation and shrimps

Three chromatographic stability-indicating methods were developed for determination of 4-hexylresorcinol in pure form and in a pharmaceutical formulation. Method A was based on a gradient elution liquid chromatographic HPLC determination of 4-hexylresorcinol, its related impurities and in presence of its degradation products. UPLC-MS/MS (Method B) was described for determination of the cited drug in presence of its degradation products. Method C was a thin- layer chromatography (TLC)-densitometry method for the separation and determination of the active ingredient, one of its related impurities and in presence of its degradation products. The mechanism of alkali, oxidative and photodegradation of 4-hexylresorcinol was studied according to ICH guidelines. The degradation products were characterized by the LC-MS/MS method. Methods A and B were applicable for determination of 4-hexylresorcinol residues in shrimp meat. The studied drug was easily degraded in alkali medium giving toxic compounds. The results obtained by the proposed methods were statistically analyzed and compared with those obtained by applying a reported method.

Effect of meat enhancement solutions with hydroxypropyl methylcellulose and konjac flour on texture and quality attributes of pale, soft, and exudative pork

The objective of this study was to determine whether addition of hydrocolloids, buffer ingredients, salt, and sodium phosphate improve the color, texture, and pH of normal and pale, soft, and exudative (PSE) meat. Specific solutions include potassium bicarbonate (KHCO), ammonium bicarbonate (NHHCO), hydroxypropyl methylcellulose (HPMC), and konjac flour (KF). Three studies were carried out. First, the stability and viscoelastic properties of the different solutions was determined. Second, fresh normal (pH 5.6-5.9) and PSE (pHu < 5.4) Longissimus dorsi muscles were ground and assigned a treatment solution: control (fresh normal), water, NaCl/SP, KHCO, NHHCO, KF, HPMC, KHCO/KF, KHCO/KF/NaCl/SP (sodium phosphate), NHHCO/HPMC, and NHHCO/HPMC/NaCl/SP. Third, treatment solutions with suitable viscoelastic properties and stability, were added, homogenized, stuffed into tubes, and cooked to an internal temperature of 75C to form gels, and torsion and texture profile analysis performed. The PSE treated samples containing bicarbonate/hydrocolloid treatments had similar hardness-first bite, hardness-second bite, and gumminess values to the normal-control samples while the NHHCO treated samples had air pockets in the cooked gel. Third, consumers (n = 92) evaluated control and PSE beef/pork frankfurters produced with the following treatments: KHCO, KHCO/HPMC, and KHCO/KF. Treatment had no effect (p > .05) on overall like/dislike of flavor, but PSE frankfurters were preferred (p < .05) to the controls. The use of KHCO with hydrocolloids, salt and SP improved the color, pH and texture properties of PSE ground pork; further research to examine the effectiveness in whole PSE pork muscle systems is needed.

PRACTICAL APPLICATIONS

Meat processors could use KHCO with HPMC or KF as ingredients to improve color, texture, and pH of PSE meat. The reduction of variation between PSE and normal pork muscle would improve pork quality and add value to PSE meat products.

Effect of sodium bicarbonate and varying concentrations of sodium chloride in brine on the liquid retention of fish (Pollachius virens L.) muscle

BACKGROUND

Negative health effects associated with excessive sodium (Na) intake have increased the demand for tasty low-Na products (<2% NaCl) rather than traditional heavily salted fish products (∼20% NaCl). This study investigates the causes of improved yield and liquid retention of fish muscle brined with a combination of salt (NaCl) and sodium bicarbonate (NaHCO3 ).

RESULTS

Water characteristics and microstructure of saithe (Pollachius virens L.) muscle brined in solutions of NaCl and NaHCO3 or NaCl alone were compared using low-field nuclear magnetic resonance (LF-NMR) T2 relaxometry, microscopy, salt content, liquid retention and colorimetric measurements. Saithe muscle was brined for 92 h in 0, 30, 60, 120 or 240 g kg(-1) NaCl or the respective solutions with added 7.5 g kg(-1) NaHCO3 . NaHCO3 inclusion improved the yield in solutions ranging from 0 to 120 g kg(-1) NaCl, with the most pronounced effect being observed at 30 g kg(-1) NaCl. The changes in yield were reflected in water mobility, with significantly shorter T2 relaxation times in all corresponding brine concentrations. Salt-dependent microstructural changes were revealed by light microscopy, where NaHCO3 supplementation resulted in greater intracellular space at 30 and 60 g kg(-1) NaCl.

CONCLUSION

Sodium bicarbonate addition to low-salt solutions can improve yield and flesh quality of fish muscle owing to altered water mobility and wider space between the muscle cells.