内容: The modern development of commercial circulation has forced the preservation of muscle foods to achieve technology innovation and transformation. Incomplete freezing is a promising technology for muscle food preservation, which can be used as a compromise strategy between traditional chilling and freezing. It can not only inhibit microorganism and enzymatic activity with a cooler environment, but also avoid the severe drip loss triggered by the generous ice crystals, thus maintaining a stable quality in the storage, transportation and consumption. However, confusing nomenclature and blurred boundary appeared in the related researches is fatal to the standardization system formation and future development. To provide a clear reference, the review describes the moisture/ice-crystal behavior succession during cooling stage of muscle foods, and takes it as guideline to classify incomplete freezing techniques into 4 categories: superchilling (from 0 °C to freezing point), micro-freezing (from freezing point to 2 °C below freezing point), partial freezing (from 2 °C below freezing point to phase-transition endpoint) and sub-freezing (from phase-transition endpoint to –18 °C). As reported, the shelf life of muscle foods could be extended by 1.4–8 times under vaious incomplete freezing compared to traditional chilling. Meaningful regulatory approaches (cryoprotectant, packaging, physical field, etc.) were also highlighted, which could further enhance the practical effects of incomplete freezing by inhibiting vital deterioration factors such as microbial growth, oxidative reactions and ice crystal formation. Finally, refinement, real-time, industrialization and digitization as main challenges were presented to provide valuable references for the future development of muscle food cold chain circulation based on incomplete freezing.

内容: As a kind of food rich in high-quality protein, poultry eggs not only play the most basic nutritional role in national life, but also widely used in bread, pastry, baking and other food industry because of its excellent processing characteristics such as foaming, emulsification and gel properties, besides its active ingredients can also develop new egg products and functional foods. China, a large country producing and consuming of poultry eggs, has ranked first in the annual production of poultry eggs since 1985. However, the consumer market is dominated by fresh eggs, whose processing conversion rate is only about 12%, and it is mainly based on traditional egg products such as salted eggs and preserved eggs. Compared with Western countries, the market share of egg powder, egg liquid, dry egg products, egg drinks, convenient egg products and other new egg products is small in China. In recent years, China’s egg industry has entered the mature stage of development, which takes a favorable trend. In 2022, the output value of China’s egg processing industry has exceeded 400 billion RMB. This paper mainly updates and interprets the history, present situation and prospect of egg processing industry in China.

内容: Food allergens are a significant concern for global public health. Enzymolysis, which includes enzymatic hydrolysis and enzymatic cross-linking, is known for its mild conditions, as well as its high efficiency and stability, making it a widely employed method to reduce the allergenicity of food proteins. A small group of eight foods-four of animal origin (milk, eggs, fish, and crustacean shellfish) and four of plant origin (tree nuts, peanuts, wheat, and soybeans) accounts for approximately 90% of all food allergies. However, there has been no comprehensive summary of how enzymolysis impacts the digestibility and allergenicity of these eight key foods, based on both in vitro and in vivo studies. This paper seeks to provide a systematic review of the influence of enzymolysis on food allergenicity, with a focus on molecular characteristics, epitopes, immunoglobulin (Ig) E/IgG binding capacity, and digestive stability during in vitro digestion. The potential immune regulation effects of enzymolysis products in cell and animal allergy models are also highlighted.

内容: The functional components known as milk oligosaccharides are crucial in the milk of diverse animals. Increasing evidence of immunomodulatory effects of milk oligosaccharides suggests that they may have some therapeutic potential in allergy. Here, we assess the effect of 3′-sialyllactose (3′-SL) on symptomatology and immune responses in a β-lactoglobulin (β-Lg)-sensitized mouse model of food allergy. Furthermore, 3′-SL mixed with 2′-fucosyllactose (2′-FL) at weight ratios of 1:6 and 1 000:1 to explore whether they had a synergies effect on alleviate sensitization. The results showed that 3′-SL and the mixture of 3′-SL and 2′-FL can regulate immune response and intestinal homeostasis. The intervention of 3′-SL and its mixture with 2′-FL can alleviate the symptoms of dermatitis, significantly reduce the serum specific-immunoglobulin (Ig) E (s-IgE) and specific-IgG1 (s-IgG1) levels (P < 0.05), reduce the accumulation of mast cells in the jejunum and maintain the diversity of the intestinal flora. 3′-SL could alleviate sensitization in a dose-dependent manner, and 3′-SL and 2′-FL have a synergies effect in reducing allergy. This study presented here opens the possibility that 3′-SL and the mixture of 3′-SL and 2′-FL in the form of nutritional ingredients could be used as adjuncts to existing treatment approaches to relieve food allergy in infants.

内容: Egg yolk peptides were prepared by enzymatic hydrolysis of defatted egg yolk powder. The cryoprotective effects of these peptides were assessed by examining the functional, structural and physicochemical properties of egg yolk. Results indicated that egg yolk peptides could reduce viscosity and prevent the accumulation of egg yolk proteins during freezing, thereby mitigating the deterioration of its functional characteristics. The peptide hydrolyzed for 3 h demonstrated the lowest fluidity in thawed egg yolk. Additionally, Fourier transform infrared (FTIR) spectra and intrinsic fluorescence spectra revealed that egg yolk peptides could reduce damage to the secondary and tertiary structures of proteins, enhancing the stability of the protein network. Changes in the content of secondary structures showed that egg yolk peptides increased β-turns, decreased β-sheets, and maintained overall structural stability and strength. This study provides new insights for egg yolk peptides to inhibit frozen egg yolk gelation.

内容: Malondialdehyde (MDA) content is a primary indicator evaluating lipid oxidation level in oil-containing foods. However, total MDA compounds (tMDA) exist in both free MDA (fMDA) and bound MDA (bMDA) forms at the stage of lipid peroxidation. The traditional spectrophotometric assay quantifies the MDA after an acid hydrolysis process, only releasing limited levels of fMDA from bMDA, which named as rMDA. Considering lack of study about the effect of hydrolysis treatments on the efficiency and result accuracy in terms of MDA detection for fish products. In this study, an alkaline hydrolysis method was compared with the conventional trichloroacetic acid (TCA) hydrolysis. The results showed that the highest MDA content was obtained under hydrolysis of surimi samples with 1 mol/L NaOH for 60 min at 60 °C, which was about 2 times of that obtained from 15 g/100 mL TCA for 30 min. The alkaline hydrolysis was proved to produce more rMDA, exhibiting higher hydrolysis efficiency over the conventional method. Present works also optimized a protocol on derivatization and liquid-liquid extraction process prior to gas chromatography-mass spectrometry quantification. The hydrolysate was firstly regulated by HCl, allowing protein to fully precipitated by the following addition of TCA. This developed liquid-liquid extraction could reduce interference from presence of protein in the aqueous phase, achieving a more sensitive result with improved precision and recovery.

内容: As an important part of modern diet, the elemental composition of pre-prepared meat (PM) directly affects consumers’ health. This study aims to reveal the true content and distribution characteristics of elements in PM through inductively coupled plasma-tandem mass spectrometry (ICP-MS/MS), providing a scientific basis for food safety regulation, nutritional assessment and product development. This study optimized the pretreatment conditions, ultimately selecting 5 mL of HNO3 + 2 mL of 30% H2O2 as the digestion reagent, and using microwave digestion conditions with a maximum temperature of 190 °C to digest the samples, and then detecting the content of various elements in PM through ICP-MS/MS. The results showed that all elements had good linear relationships with the linear correlation coefficients greater than 0.999 7. The detection limits ranging from 0.620 to 421 ng/L, the spiked recoveries reach 93.4%–105.0%, and the relative standard deviations less than 5.89%. The measurement results of the national standard chicken meat substance (GBW10018) are all within the standard deviation range of the standard value, which indicates that this method has high accuracy and precision and is suitable for the detection of PM products. Using this method, we evaluated the content of 22 elements in PM, including pork, beef, mutton, chicken and duck meat. The results showed that the contents of Ca, Mg, Zn, and Fe in the five types of PM were relatively high, while the contents of heavy metal elements were very low. This study provides technical support for the strict monitoring of PM, which also offers consumers a more transparent and secure basis for food selection, thereby promoting the popularization of healthy eating concepts.

内容: As a serious threat to the broiler industry, woody breast (WB) requires precise classification that is theoretically aligned with the advantage of bioelectrical impedance detection. This research used normal chicken breast (NORM) and three levels of WB condition, namely, mild, moderate and severe (SEV), based on sensory evaluation. The basic objective quality indicators and impedance characteristics of the samples were detected, and then the various levels of WB were categorized by model-classification approach. At a consistent frequency, the impedance amplitude of samples decreased with increased WB level. Significant differences in the absolute value of the phase angle existed among different levels of WB. The increase in WB level led to a considerable increase in intracellular resistance (Ri) and in the characteristic frequency (fc). However, four other indices including the radius of Cole-Cole curve arc, the extracellular resistance (Re), the polarization coefficient (K), and the relaxation factor (α) substantially dropped with increased WB level. The accuracy of SEV training, NORM and SEV test samples achieved a perfect score of 100% according to the partial least squares (PLS) prediction model. The PLS model also exhibited an overall accuracy of 91.70% for training samples compared with the value of 88.35% from limitedmemory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) deep-learning prediction model. However, the L-BFGS model achieved a higher overall correct rate for test samples (90.00%) than PLS model (80.00%). These results provided valuable information for the classification of WB based on the characteristics of bioelectrical impedance.

内容: During the lactic acid tenderization process of yak meat, an observable phenomenon is the color browning. To delve into the underlying causes and devise solutions, this study meticulously injected varying concentrations and volumes of lactic acid into yak meat samples, the freshness and color appearance of the meat were assessed by measuring metmyoglobin (MetMb) content, color parameters, lipid oxidation levels, and conducting sensory evaluations. Furthermore, the mechanisms behind the color alterations were elucidated by quantifying the activity of MetMb reductase and lactate dehydrogenase (LDH). The results indicated that when lactic acid was introduced at a concentration of 0.4 mol/L, accompanied by an injection volume equivalent to 2.5% of the meat weight, yak meat underwent a marked browning. This transformation was primarily attributed to the diminished MetMb reductase activity. Under specific pH conditions, augmented mitochondrial respiration fosters the formation of MetMb, culminating in its substantial accumulation and subsequently altering the color of the yak meat. Conclusively, this research underscores that the combined factor of injecting lactic acid at a concentration of 0.4 mol/L and a volume corresponding to 2.5% of the meat weight serves as a crucial catalyst for the browning of yak meat, emphasizing the need for careful regulation of these parameters during the tenderization process.

内容: Milk-derived extracellular vesicles (mEVs) derived from bovine colostrum (C-mEVs) and mature milk (M-mEVs) are known to carry bioactive molecules with significant immunomodulatory properties and biological effects. However, most research on mEVs has focused on their proteomics, lipidomics, and transcriptome, while metabolome analysis are still lacking. This study aims to explore the metabolomic profiles of C-mEVs and M-mEVs to uncover their molecular characteristics and potential biological functions. The mEVs were purified from both bovine colostrum and mature milk using ultracentrifugation combined with size exclusion chromatography. Through untargeted metabolomic analysis employing liquid chromatography-tandem mass spectrometry (LC-MS/MS), 76 differential metabolites, such as leucylproline, levonordefrin, adenine, polyglycerol esters of fatty acids, and hypoxanthine were identified. Among them, lipid-related metabolites were the most prominent. Hierarchical cluster analysis and principal component analysis revealed distinct metabolic signatures between C-mEVs and M-mEVs. Pathway enrichment analysis indicated that the metabolites were involved in purine metabolism and ABC transporter pathways, which was closely related to cancer, inflammation, gastrointestinal disorders, and metabolic diseases. The findings highlight the potential of metabolomics to provide a temporally precise and detailed snapshot of the molecular properties of mEVs, contributing valuable insights into mEVs-mediated molecular mechanisms and offering new avenues for research into their biological effects and therapeutic applications.