A comprehensive review on functional properties of preserved eggs as an excellent food ingredient with anti-inflammatory and anti-cancer aspects

Sodium sulfate addition increases the bioresource of biologically active sulfated polysaccharides from Antrodia cinnamomea

Fungal sulfated polysaccharides (SPS) have been used in the pharmaceutical industry. In this study, sodium sulfate was employed as an elicitor to induce stress on the mycelia of Antrodia cinnamomea for the biosynthesis of SPS with high sulfate content. Sodium sulfate treatments increased the yield of SPS to 4.46 % and increased the sulfate content to 6.8 mmol/g of SPS. SPS were extracted from A. cinnamomea cultured with 500 mM sodium sulfate; these SPSs are denoted as Na500. Na500 exhibited the highest sulfate content and dose-dependent inhibitory activity against LPS-induced production of macrophage interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), and interleukin 1β (IL-1β). Mechanistically, Na500 hindered the phosphorylation of transforming growth factor-β receptor II (TGFRII), extracellular signal-regulated kinases (ERK), and protein kinase B (AKT) expression. A purified 7.79 kDa galactoglucan, Na500 F3, augmented the anti-inflammation activity by inhibiting LPS-induced TGFβ release. Additionally, Na500 F3 restrained the LPS-induced phosphorylation of p-38, ERK, AKT, and TGFRII in RAW264.7 cells. Na500 F3 impeded the proliferation of lung cancer H1975 cells by inhibiting the phosphorylation of focal adhesion kinase, ERK, and Slug. The anti-inflammation and anticancer properties of Antrodia SPS contribute to its health benefits, suggesting its utility in functional foods.

Effect of preserved eggs on the health of SD rats, and anti-tumor action of HT-29 cells

Preserved eggs are traditional alkali-pickled food in China and have been enjoyed by consumers and extensively studied by researchers for their nutritional tastes and their anti-tumor, anti-inflammatory, antioxidant, lipid-lowering, and blood pressure-lowering properties. To study the anti-tumor effects of preserved eggs, this project observed the health on rats, and anti-tumor effects and separated anti-tumor active components on HT-29 cells. SD rats fed for 80 days showed that preserved eggs had no significant effect on weight, food intake, blood pH, liver tissues, or organ indices. Preserved eggs significantly increased blood levels of oxidative stress markers SOD and CAT, decreased MDA levels by 0.46, 0.23, and 0.25 times. Moreover, they also increased the level of IL-2 from 1233 to 1340 pg/mL. Two water-soluble bioactive peptide fractions, B1 and B2, with molecular weights ≥10 kDa were further obtained from preserved eggs by ultrafiltration and Superdex Peptide 10/300 GL. The potential mechanism of B1 and B2 is to activate the internal mitochondrial apoptotic pathway and induce apoptosis by up-regulating the expression of the pro-apoptotic factors cytochrome C, caspase-3, and caspase-9 mRNA in HT-29 cells.

Addition of NaCl or Sucrose on the Protein Content, and Functional and Physicochemical Properties of Egg Whites Liquid under Heat Treatment

In this study, differences in the protein content and functional and physicochemical properties of four varieties of egg white (EW) were studied by adding 4-10% sucrose or NaCl and then heating them at 70 °C for 3 min. According to a high-performance liquid chromatography (HPLC) analysis, the percentages of ovalbumin, lysozyme and ovotransferrin rose with an increase in the NaCl or sucrose concentration; however, the percentages of ovomucin and ovomucoid decreased. Furthermore, the foaming properties, gel properties, particle size, α-helixes, β-sheets, sulfhydryl groups and disulfide bond content also increased, whereas the content of β-turns and random coils decreased. In addition, the total soluble protein content and functional and physicochemical properties of black bone (BB) chicken and Gu-shi (GS) EWs were higher than those of Hy-Line brown (HY-LINE) and Harbin White (HW) Ews (p < 0.05). Subsequently, transmission electron microscopy (TEM) confirmed the changes in the EW protein structure in the four varieties of Ews. As the aggregations increased, the functional and physicochemical properties decreased. The protein content and functional and physicochemical properties of Ews after heating were correlated with the concentration of NaCl and sucrose and the EW varieties.

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.

The changes of umami substances and influencing factors in preserved egg yolk: pH, endogenous protease, and proteinaceous substance

The study investigated the changes of nucleotides, succinic acid, and free amino acids amounts in yolk and the causes leading to the changes after pickling to uncover the fundamental umami component of preserved egg yolk. The findings demonstrated that while the contents of 5′-adenosine monophosphate (AMP), 5′-cytidine monophosphate (CMP), 5′-guanosine monophosphate (GMP), 5′-uridine monophosphate (UMP), and succinic acid increased after slightly decreasing aspartic acid (Asp) content in preserved egg yolk increased gradually. The contents of 5′-inosine monophosphate (IMP) and other free amino acids were gradually decreased. Comparing the taste activity value (TAV), it was found that the single umami substance, succinic acid, played a key role in inducing the umami taste. In combination with the Spearman correlation analysis, it was shown that the proteinaceous substance, which is the most significant umami component in preserved egg yolk, tended to condense first and subsequently disintegrate in an alkaline environment. The orthogonal partial least squares analysis (OPLS) found that pH was also affected by the changes in proteinaceous substance. These findings offer suggestions for enhancing the pickling procedure and investigating the optimal pickling period for preserved eggs.

The current research status and strategies employed to modify food-derived bioactive peptides

The ability of bioactive peptides to exert biological functions has mainly contributed to their exploitation. The exploitation and utilization of these peptides have grown tremendously over the past two decades. Food-derived peptides from sources such as plant, animal, and marine proteins and their byproducts constitute a more significant portion of the naturally-occurring peptides that have been documented. Due to their high specificity and biocompatibility, these peptides serve as a suitable alternative to pharmacological drugs for treating non-communicable diseases (such as cardiovascular diseases, obesity, and cancer). They are helpful as food preservatives, ingredients in functional foods, and dietary supplements in the food sector. Despite their unique features, the application of these peptides in the clinical and food sector is to some extent hindered by their inherent drawbacks such as toxicity, bitterness, instability, and susceptibility to enzymatic degradation in the gastrointestinal tract. Several strategies have been employed to eliminate or reduce the disadvantages of peptides, thus enhancing the peptide bioactivity and broadening the opportunities for their applications. This review article focuses on the current research status of various bioactive peptides and the strategies that have been implemented to overcome their disadvantages. It will also highlight future perspectives regarding the possible improvements to be made for the development of bioactive peptides with practical uses and their commercialization.

Ions-regulated aggregation kinetics for egg white protein: A promising formulation with controlled gelation and rheological properties

This study aims to evaluate the structure of ions-regulated gelation of egg white protein (EWP) via aggregation kinetics model, which was built by monitoring turbidity. Results showed that compared with NaCl and KCl, the addition of Na₂SO₄ increased free sulfhydryl content, surface hydrophobicity and particle size of EWP significantly, while weakened the order of secondary structure. Hence, strengthened gel network structure was observed with higher porosity, which improved the texture profiles and rheological properties of EWP gels. Based on these phenomena above, the relationship between aggregation behavior and gelling properties with ions was further investigated by aggregation kinetics model and principal component analysis. Because of the enhancement of protein interactions, the aggregation growth rate with Na₂SO₄ was much faster than the samples with NaCl, which reflected over-aggregation due to the accelerated nucleation process and resulted in firmed gel network structure.