Effects of CaCl2 on salting kinetics, water migration, aggregation behavior and protein structure in rapidly salted separated egg yolks

Sucrose-phosphate osmotic system improves the quality characteristics of reduced-salt salted egg yolk: Profiling from protein structure and lipid distribution perspective

This paper was dedicated to the study of the effect of sucrose-phosphate on aspects of physicochemical properties, lipid distribution and protein structure during the picklig of reduced-salt salted egg yolk (SEY). This work constructed a reduced-salt pickling system from a new perspective (promoting osmosis) by using a sucrose-phosphate-salt. Results showed that SEY-28d achieved a desirable salt content (1.07 %), hardness (573.46 g) and springiness (0.65 g). The matured SEY was in excellent quality with orange-red color and loose sandy texture. This was because the lipoprotein aggregated with each other through hydrophobic interaction to form a stable network structure. In addition, the hypertonic environment accelerated salt penetration. These also created good condition for lipid spillage. The results of confocal laser scanning microscope also verified this phenomenon. This work provides important guidance for new reduced-salt curing of traditional pickled foods, deep processing of SEY, and industry development in the field of poultry egg.

Testing adulterated liquid-egg: developing rapid detection techniques based on colorimetry, electrochemistry, and interfacial fingerprinting

To develop rapid detection techniques for liquid eggs' adulteration, three types of adulterations were considered: water dilution, manipulation of yolk ratio in whole egg, and blending different varieties of egg white or yolk. Objective: Establish detection techniques utilizing colorimetry, electrochemistry, and interfacial fingerprinting for these adulterations, respectively. Results: Colorimetry allows for detection (1 min·sample-1) of water dilution through linear (R2 ≥ 0.984) and exponential fitting (R2 ≥ 0.992); Electrochemistry enables detection (6 min·sample-1, R2 ≥ 0.979) of the adulteration of yolk ratio in whole egg; Interfacial fingerprinting technique effectively detects (detection duration: 10 min·sample-1, detection limit: 1.0-10.0 wt%) the adulteration of different varieties of egg white. Subsequently, through 3D-fluorescence microscopy (interface height variation: 22.49-573.45 μm), interfacial tension variation (65.54-35.48 mN·m-1), contact angle variation (89.7°-32.9°), particle size range (free water: 0.94-14.29 μm; protein aggregation: 6.57-10.76 μm), and etc., interfacial fingerprinting mechanism was elucidated. This research contributes novel insights into the detection of adulteration in liquid eggs.

Insight into the evolution of textural properties and juiciness of ready-to-eat chicken breasts upon different thermal sterilization: From the perspective of protein degradation

Texture deterioration of meat products upon high-temperature sterilization is a pressing issue in the meat industry. This study evaluated the effect of different thermal sterilization temperatures on the textural and juiciness of ready-to-eat (RTE) chicken breast. In this study, by dynamically monitoring the texture and juiciness of chicken meat products during the process of thermal sterilization, it has been observed that excessively high sterilization temperatures (above 100°C) significantly diminish the shear force, springiness and water-holding capacity of the products. Furthermore, from the perspective of myofibrillar protein degradation, molecular mechanisms have been elucidated, unveiling that the thermal sterilization treatment at 121°C/10 min triggers the degradation of myosin heavy chains and F-actin, disrupting the lattice arrangement of myofilaments, compromising the integrity of sarcomeres, and resulting in an increase of approximately 40.66% in the myofibrillar fragmentation index, thus diminishing the quality characteristics of the products. This study unravels the underlying mechanisms governing the dynamic changes in quality of chicken meat products during the process of thermal sterilization, thereby providing theoretical guidance for the development of high-quality chicken products.

The effects of sucrose/NaCl combined pickling on the textural characteristics, moisture distribution, and protein aggregation behavior of egg yolk

Salted egg yolks have a tender, loose, gritty, and oily texture and are commonly employed as fillings in baked goods. This study investigated the formation mechanism of egg yolk gels using three different pickling methods: NaCl, sucrose, and mixed groups. The results revealed that of these pickling methods, egg yolks pickled with the mixture had the lowest moisture content (11.59% at 25°C and 10.21% at 45°C), almost no free water content, and the highest hardness (19.11 N at 25°C and 31.01 N at 45°C). Intermolecular force measurements indicated that pickling with the mixture mitigated the surface hardening effect of sucrose and facilitated protein cross-linking. Moreover, confocal laser scanning microscopy of the egg yolk gels pickled with the mixture displayed macromolecular aggregates and oil exudation, suggesting that this method partially disrupted the lipoprotein structure and notably promoted yolk protein aggregation and lipid release. Overall, egg yolks formed a dense gel via the mixed pickling method owing to the ionic concentration and dehydration effects. These findings show the impact of NaCl and sucrose in pickling egg yolks, providing a crucial foundation for developing innovative and desirable egg yolk products. PRACTICAL APPLICATION: This study introduces a novel pickling strategy that combines sucrose and NaCl for egg yolk processing. The egg yolk pickled using this method exhibited improved quality according to the evaluated textural characteristics, moisture distribution, and protein aggregation behavior. The findings may broaden the use of sucrose as a pickling agent for egg yolk processing and provide new ideas for developing and producing pickled eggs and other food products.

Effects of freezing on the gelation behaviors of liquid egg yolks affected by saccharides: thermal behaviors and rheological and structural changes

Monitoring and controlling the freezing process and thermal properties of foods is an important means to understand and maintain product quality. Saccharides were used in this study to regulate the gelation of liquid egg yolks induced by freeze‒thawing; the selected saccharides included sucrose, L-arabinose, xylitol, trehalose, D-cellobiose, and xylooligosaccharides. The regulatory effects of saccharides on frozen egg yolks were investigated by characterizing their thermal and rheological properties and structural changes. The results showed that L-arabinose and xylitol were effective gelation regulators. After freeze‒thawing, the sugared egg yolks exhibited a lower consistency index and fewer rheological units than those without saccharides, indicating controlled gelation. Weaker aggregation of egg yolk proteins was confirmed by smaller aggregates observed by confocal laser scanning microscopy and smaller particle sizes. Saccharides alleviated the freeze-induced conversion of α-helices to β-sheets in egg yolk proteins, exposing fewer Trp residues. Overall, L-arabinose showed the greatest improvement in regulating the gelation of egg yolks, followed by xylitol, which is correlated with its low molecular weight.

Simultaneous Determination of Steroids and NSAIDs, Using DLLME-SFO Extraction and HPLC Analysis, in Milk and Eggs Collected from Rural Roma Communities in Transylvania, Romania

This research aims to determine five steroids and four non-steroidal anti-inflammatory drugs in milk and egg samples collected from rural Roma communities in Transylvania, Romania. Target compounds were extracted from selected matrices by protein precipitation, followed by extract purification by dispersive liquid-liquid microextraction based on solidification of floating organic droplets. The extraction procedure was optimized using a 24 full factorial experimental design. Good enrichment factors (87.64-122.07 milk; 26.97-38.72 eggs), extraction recovery (74.49-103.76% milk; 75.64-108.60% eggs), and clean-up of the sample were obtained. The method detection limits were 0.74-1.77 µg/L for milk and 2.39-6.02 µg/kg for eggs, while the method quantification limits were 2.29-5.46 µg/L for milk and 7.38-18.65 µg/kg for eggs. The steroid concentration in milk samples was Collapse

Key Words

• dispersive liquid–liquid microextraction based on solidification of floating organic droplets (DLLME-SFO)
• eggs
• milk
• non-steroidal anti-inflammatory drugs (NSAIDs)
• rural Roma communities
• steroids

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MESH Headings

• Humans
• Animals
• Anti-Inflammatory Agents, Non-Steroidal
• Ketoprofen
• Naproxen
• Ibuprofen
• Milk
• Romania
• Chromatography, High Pressure Liquid
• Roma
• Estrone

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Grants

• Project contract no. 23 / 2020 EEA and Norway Grants

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Affiliation(s)

Mihaela Cătălina Herghelegiu Faculty of Environmental Science and Engineering, Babeș-Bolyai University, 1 Kogălniceanu Str., 400084 Cluj-Napoca, Romania
Vlad Alexandru Pănescu Faculty of Environmental Science and Engineering, Babeș-Bolyai University, 1 Kogălniceanu Str., 400084 Cluj-Napoca, Romania
Victor Bocoș-Bințințan Faculty of Environmental Science and Engineering, Babeș-Bolyai University, 1 Kogălniceanu Str., 400084 Cluj-Napoca, Romania
Radu-Tudor Coman Faculty of Medicine, “Iuliu Hațieganu” University of Medicine and Pharmacy, 8 Babeș Str., 400012 Cluj-Napoca, Romania
Vidar Berg Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 1433 Ås-Oslo, Norway
Jan Ludvig Lyche Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 1433 Ås-Oslo, Norway
Maria Concetta Bruzzoniti Department of Chemistry, University of Turin, Via P. Giuria 5, 10125 Turin, Italy;
Mihail Simion Beldean-Galea Faculty of Environmental Science and Engineering, Babeș-Bolyai University, 1 Kogălniceanu Str., 400084 Cluj-Napoca, Romania

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Effects of CaCl2 on the structure of high-density lipoprotein and low-density lipoprotein isolated from rapidly salted separated egg yolk

According to previous research, adding CaCl2 to the salting solution improves the quality of salted separated egg yolk. To further understand the improvement mechanism of CaCl2, this paper investigated the effect of CaCl2 on the structure of high-density lipoprotein (HDL) and low-density lipoprotein (LDL) during the salting process. The results indicated that the addition of CaCl2 can affect the composition of HDL and LDL apolipoproteins, improving the orderliness of the HDL structure and the looseness of the LDL structure. It was discovered by atomic force microscopy (AFM) that adding CaCl2 to the salting solution can weaken the aggregation behavior of HDL. Simultaneously, the addition of CaCl2 decreased the relative content of intermolecular β-sheets in the secondary structure of HDL and LDL, influenced their tertiary conformation, and prevented HDL and LDL from participating in the formation of a three-dimensional gel structure by influencing their hydrogen bonds and hydrophobic interactions.

Synergistic effect and mechanism of cellulose nanocrystals and calcium ion on the film-forming properties of pea protein isolate

The current serious environmental problems have greatly encouraged the design and development of food packaging materials with environmental protection, green, and safety. This study aims to explore the synergistic effect and corresponding mechanism of cellulose nanocrystals (CNC) and CaCl2 to enhance the film-forming properties of pea protein isolate (PPI). The combination of 0.5 % CNC and 4.5 mM CaCl2 resulted in a 76.6 % increase in tensile strength when compared with pure PPI-based film. Meanwhile, this combination effectively improved the barrier performance, surface hydrophobicity, water resistance, and biodegradability of PPI-based film. The greater crystallinity, viscoelasticity, lower water mobility, and improved protein spatial conformation were also observed in CNC/CaCl2 composite film. Compared with the control, the main degradation temperature of composite film was increased from 326.23 °C to 335.43 °C. The CNC chains bonded with amino acid residue of pea protein at specific sites via non-covalent forces (e.g., hydrogen bonds, Van der Waals forces). Meanwhile, Ca2+ promoted the ordered protein aggregation at suitable rate and degree, accompanied by the formation of more disulfide bonds. Furthermore, proper Ca2+ could strengthen the cross-linking and interaction between CNC and protein, thereby establishing a stable network structure. The prepared composite films are expected to be used for strawberry preservation.

Effects of CaCl2 on the rheology, microstructure and protein structures of rapidly salted separated egg yolk

Bivalent or trivalent metal salts can enhance the oil output and sandiness of salted eggs. We added CaCl2 to the salting solution to improve the quality of rapidly salted separated egg yolk and investigated its effect on rheological, microstructure, and protein structure. According to the findings, adding CaCl2 to the salting solution can promote the precipitation of egg yolk water, increase its viscosity, induce protein aggregation, and increase the denaturation temperature of the protein. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) revealed that the inner boundary of egg yolk salted with CaCl2 was clearer and that the number and size of salted egg yolk lipoprotein aggregates were larger than those of egg yolk salted without CaCl2. Analysis using Fourier transform infrared spectroscopy (FTIR) demonstrated that CaCl2 caused the interconversion of the secondary-level structure. CaCl2 can have an impact on the microenvironment of amino acid residues, according to the results of 3D fluorescence and UV absorption spectra. Therefore, adding CaCl2 can accelerate the loss of water and change the structure of lipoprotein in egg yolk, which improves the sandiness and oil yield of salted separated egg yolk.

Supplemental methionine selenium effects on egg yolk physicochemical, functional, and protein structure during storage

To clarify the effect of the addition of methionine selenium on the physicochemical, functional, and protein structural properties of egg yolk during storage. We analyzed the changes in the main indicators of egg yolks stored at 4°C and 25°C for 28 days. The results showed that the increase in water content and pH, and the decrease in absolute zeta potential and apparent viscosity of the selenium-rich egg yolks (Se-group) during storage were smaller than those of the control group egg yolks (C-group). In addition, the antioxidant capacity and emulsifying ability of the Se-group during storage were better than those of the C-group. Simultaneously, the hardness and chewiness of the Se-group gel during storage were lower than those of the C-group. The protein structure results showed that selenium rich treatment did not affect the secondary structure of egg yolk protein during storage but could improve the fluorescence intensity of the egg yolk protein. Therefore, the addition of methionine selenium can reduce the degree of deterioration in the physicochemical properties of egg yolk during storage and extend its shelf life.

A Comparative Study of Pickled Salted Eggs by Positive and Negative Pressure-Ultrasonic Method

In this study, the positive and negative pressure-ultrasonic method was applied to salted egg pickling, compared with traditional pickled salted eggs by various physical and chemical indicators. Results indicated the salt content of egg white and egg yolk increased rapidly in the salt-preserved salted egg with the positive and negative pressure-ultrasonic method, and the moisture content decreased rapidly. In addition, the oil yield of egg yolk was marinated for 12 days compared with the normal method of 35 days, and the ripening time of salted eggs was shortened by 2/3. There was no obvious difference in the microscopical structure of the egg yolk between the two methods of pickling. Moreover, the pores on the eggshell of the salted egg that was marinated by the positive and negative pressure-ultrasonic method had big cracks, which was beneficial to the substance exchange of the eggs and the outside. The common volatile flavor substances were detected by GC-MS, and a total of 33 flavor constituents were detected. There was no significant difference between the content of alcohols, aldehydes, and ketones, which contributed greatly to the flavor. Overall, the results indicated that this innovative salted eggs method can significantly reduce the curing time while ensuring the quality of salted eggs.