Ultrasound accelerates pickling of reduced-sodium salted duck eggs: an insight into the effect on physicochemical, textural and structural properties

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.

A review of the world's salt reduction policies and strategies - preparing for the upcoming year 2025

Excessive consumption of dietary sodium is a significant contributor to non-communicable diseases, including hypertension and cardiovascular disease. There is now a global consensus that regulating salt intake is among the most cost-effective measures for enhancing public health. More than half of the countries worldwide have implemented multiple strategies to decrease salt consumption. Nevertheless, a report on sodium intake reduction published by the World Health Organization revealed that the world is off-track to meet its targeted reduction of 30% by 2025. The global situation regarding salt reduction remains concerning. This review will center on domestic and international salt reduction policies, as well as diverse strategies, given the detrimental effects of excessive dietary salt intake and the existing global salt intake scenario. Besides, we used visualization software to analyze the literature related to salt reduction research in the last five years to explore the research hotspots in this field. Our objective is to enhance public awareness regarding the imperative of reducing salt intake and promoting the active implementation of diverse salt reduction policies.

Non-destructive detection of egg white and yolk morphology transformation and salt content of salted duck eggs in salting by hyperspectral imaging

Salt content is a crucial indicator of the maturity and internal quality of salted duck eggs (SDEs) during the pickling process. However, there is currently no valid and rapid method available for accurately detecting salt content. In the present study, we utilized hyperspectral imaging to no-destructively determine the salt content in egg yolks, egg whites, and whole eggs during the curing period. Firstly, principal component analysis was applied to explain the characteristics of egg yolk and white morphology transformation of SDEs with different maturities during curing. Secondly, sensitive spectral factors representative of changes in the salt content of SDEs were extracted by three spectral transformations (Savitzky-Golay SG, continuum removal CR, and first-order derivation FD) and three approaches of selecting characteristic wavelengths (successive projection algorithm SPA, uninformative variables elimination UVE and competitive adaptive reweighting sampling algorithm CARS). The results of the PLSR model suggested that the optimal models for predicting salt content in egg yolks, whites, and whole eggs were SG-UVE-PLSR (predicted coefficient of determination Rp2=0.912, predicted standard deviation SEp=0.151, residual prediction deviation RPD = 3.371), CR-CARS-PLSR (Rp2=0.873, SEp=0.862, RPD = 2.806), and CR-UVE-PLSR (Rp2=0.877, SEp=0.680, RPD = 2.851), respectively. Eventually, the optimal prediction model for the salt content of the whole egg was employed to a pixel spectral matrix to calculate the salt content values of pixel points on the hyperspectral image of SDEs. Additionally, pseudo-color techniques were employed to visualize the spatial distribution of predicted salt content. This work will provide a theoretical foundation for rapidly detecting maturity and enabling high-throughput quality sorting of SDEs.

Study on the mechanism of improving the quality of salted egg yolks by ultrasonic synergistic NaCl dry-curing

The dry separate curing of duck egg yolks was carried out by ultrasonic synergize NaCl (sodium chloride) and NaCl alone. The mechanism of the amelioration of salted egg yolk quality by ultrasonic synergistic NaCl dry-curing was studied. The quality variations of the salted egg yolks were analyzed for the same curing time and NaCl content achieved by ultrasonic synergistic NaCl curing and NaCl curing alone. The results showed that under the same salting time, the NaCl content, oil exudation and chewiness of U48-SEY (ultrasonic for 48 h-salted egg yolk) were higher than those in SEY (salted egg yolk). At the same NaCl content, the oil exudation and chewiness of U44-SEY (ultrasonic for 44 h-salted egg yolk) were still significantly increased. Compared to SEY, the soluble protein content and H0 of U44-SEY and U48-SEY were augmented. Scanning electron microscopy (SEM) indicated that the polyhedral particles in the salted egg yolks prepared by ultrasonic synergistic NaCl dry-curing were closely aligned and evenly distributed, and the salted egg yolks were sandier. Structural analysis revealed that the secondary and tertiary structures of egg yolk protein were changed although the ultrasonic synergistic NaCl dry-curing did not cause the fragmentation or aggregation of the peptide chain structure. The above results suggested that ultrasonic not only perfected the quality of salted egg yolk by promoting NaCl penetration, but also modified the structures of egg yolk protein by the action of ultrasonic itself, which prominently improved the quality of salted egg yolks.

Improvement of foaming properties of ovalbumin: Insights into the synergistic effect of preheating and high-intensity ultrasound on physicochemical properties and structure analysis

Ovalbumin (OVA), characterized by its high concentration in eggs, possesses remarkable foaming properties. Nevertheless, OVA is highly sensitive to thermal changes and acid-base conditions, substantially hampering its application potential for foaming purposes within the food industry. This experiment aimed to examine the effects of preheating and high-intensity ultrasound (HIU) treatment at different powers on OVA foaming properties and explore the underlying mechanisms. The results revealed that OVA exhibited the highest foaming capacity (31.5 %) and foaming stability (96.7 %) under the treatment condition of 200w + 60°C. Additionally, significant improvements were observed in the content of free sulfhydryl groups (37.27 μmg/g), solution viscosity (142.33 mPa·s), and surface hydrophobicity (37.27 μg BPB) under this condition. The absolute value of the zeta potential (-10.28 mV) was significantly increased in the 200w + 60°C treatment group. Moreover, the polymer dispersity index of OVA (0.6045) was significantly reduced, resulting in improved dispersion than the control group. The structural analysis revealed significant changes in the α-helix and β-sheet content of OVA after treatment at 200w + 60 °C. The X-ray diffraction pattern exhibited sharper peaks, indicating a crystal structure, and the fluorescence peak displayed a slight blue shift along with increased hydrophobicity. Moreover, the preheating and HIU treatment induced a continuous uneven and irregular pore structure in OVA, which ultimately enhanced its foaming properties. In conclusion, the preheating and HIU treatment offers a novel approach to enhance the foaming properties of OVA.

Effect of sodium salt on meat products and reduction sodium strategies - A review

Sodium salt is one of the important additives in food processing. However, excessive intake of sodium salt may cause a series of cardiovascular diseases. Nowadays, sodium intake in most countries is higher than the World Health Organization recommends maximum consumption (5 g/d). 20% of the sodium intake in diets comes from meat products. Therefore, reducing the content of sodium salt in meat products and developing sodium salt-reduction meat products have attracted more and more attention for consumers. In this paper, the roles of sodium salt in meat product processing were reviewed. At the same time, sodium salt reduction strategies and existing problems were summarized and discussed. Multiple factors need to be considered to improve the salt-reduction meat product's quality. Relying on a single technology has a narrow application area, and it is difficult to achieve salt reduction. Therefore, a combination of multiple strategies could obtain a more ideal effect.

Changes in physicochemical properties and lipid oxidation lead to the formation of mud on salted egg yolks during storage

Salted egg yolk (SEY) becomes easily "muddy" during storage, leading to a decrease in the quality of salted eggs. The mechanism of SEY mudding was studied in this paper. The results showed that SEY hydrogen proton binding decreased, and SEY water and lipid fluidity increased during storage. In addition, the degree of lipid oxidation and monounsaturated fatty acids in salted egg yolk lipids (SEYL) increased, and primary oxidation products and secondary oxidation products were formed. Moreover, the structure of SEY was degraded to release lipids and proteins, and these proteins and lipids were re-emulsified to form new aggregates. Finally, by PLS-DA modeling analysis, it was found that the content of ω-3 polyunsaturated fatty acids and phospholipids changed significantly after SEY became muddy. These results suggest that the muddiness of SEY can primarily be attributed to higher fluidity and protein-lipid re-emulsification, and secondarily to the oxidation of SEYL.

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.

A review on the development of pickled eggs: rapid pickling and quality optimization

Pickled eggs enjoy a long processing history with unique flavor and rich nutrition but suffer from long pickling cycle due to the limitations of traditional processing methods. In terms of quality, salted egg whites have the disadvantage of high sodium content, and salted egg yolks have problems such as hard core and black circle around outer layer. Likewise, the quality of preserved eggs is challenged by the black spots (dots) on the eggshells and the high content of heavy metals in the egg contents. The sustainable development of traditional pickled eggs are hindered by these defects and extensive research has been carried out in recent years. Based on the elaboration of the quality formation mechanism of salted eggs and preserved eggs, this paper reviewed the processing principles and applications of rapid pickling technologies like ultrasonic technology, magnetoelectric-assisted technology, water cycle technology, vacuum decompression technology, and pulsed pressure technology, as well as the quality optimization methods such as controlling the sodium content of the salted egg whites, improving the quality of salted egg yolks, promoting the quality of lead-free preserved eggs, and developing heavy metal-free preserved eggs. In the end, the future development trend of traditional pickled eggs was summarized and prospected in order to provide theoretical guidance for the actual production.