With the emphasis placed by society on environmental resources, current petroleum-based packaging in the food industry can no longer meet people’s needs. However, new active packaging technologies have emerged, such as proteins, polysaccharides, and lipids, in which proteins are widely used for their outstanding gel film-forming properties. Most of the current literature focuses on research applications of single protein-based films. In this paper, we review the novel protein-based packaging technologies that have been used in recent years to categorize different proteins, including plant proteins (soybean protein isolate, zein, gluten protein) and animal proteins (whey protein isolate, casein, collagen, gelatin). The advances that have recently been made in protein-based active packaging technology can be understood by describing protein sources, gel properties, molding principles, and applied research. This paper presents the current problems and prospects of active packaging technology, provides new ideas for the development of new types of packaging and the expansion of gel applications in the future, and promotes the development and innovation of environmentally friendly food packaging.

Intestinal epithelial barrier function is closely associated with the development of many intestinal diseases. Heat-killed Lacticaseibacillus paracasei (HK-LP) has been shown to improve intestinal health and enhance immunity. However, the function of HK-LP in the intestinal barrier is still unclear. This study characterized the inflammatory effects of seven HK-LP (1 μg/mL) on the intestinal barrier using lipopolysaccharide (LPS) (100 μg/mL)-induced Caco-2 cells. In this study, HK-LP 6105, 6115, and 6235 were selected, and their effects on the modulation of inflammatory factors and tight junction protein expression (claudin-1, zona occludens-1, and occludin) were compared. The effect of different cultivation times (18 and 48 h) was investigated in response to LPS-induced intestinal epithelial barrier dysfunction. Our results showed that HK-LP 6105, 6115, and 6235 improved LPS-induced intestinal barrier permeability reduction and transepithelial resistance. Furthermore, HK-LP 6105, 6115, and 6235 inhibited the pro-inflammatory factors (TNF-α, IL-1β, IL-6) and increased the expression of the anti-inflammatory factors (IL-4, IL-10, and TGF-β). HK-LP 6105, 6115, and 6235 ameliorated the inflammatory response. It inhibited the nuclear factor kappa B (NF-κB) signaling pathway-mediated myosin light chain (MLC)/MLC kinase signaling pathway by downregulating the Toll-like receptor 4 (TLR4)/NF-κB pathway. Thus, the results suggest that HK-LP 6150, 6115, and 6235 may improve intestinal health by regulating inflammation and TJ proteins. Postbiotics produced by these strains exhibit anti-inflammatory properties that can protect the intestinal barrier.

This study explored the Maillard reaction process during the glycation of soy protein isolate (SPI) with galacto-oligosaccharides (GOSs) under high-pressure homogenization (HPH) and its effects on the emulsifying properties of SPI. SPI-GOS glycation under moderate pressure (80 MPa) significantly inhibited the occurrence and extent of the Maillard reaction (p < 0.05), but homogenization pressures in the range of 80–140 MPa gradually promoted this reaction. HPH caused a decrease in the surface hydrophobicity of the glycated protein, an increase in the abundance of free sulfhydryl groups, unfolding of the protein molecular structure, and the formation of new covalent bonds (C=O, C=N). Additionally, the particle size of emulsions created with SPI-GOS conjugates was reduced under HPH, thus improving the emulsifying properties of SPI. A reduction in particle size (117 nm), enhanced zeta potential (−23 mV), and uniform droplet size were observed for the emulsion created with the SPI-GOS conjugate prepared at 120 MPa. The conformational changes in the glycated protein supported the improved emulsification function. All results were significantly different (p < 0.05). The study findings indicate that HPH provides a potential method for controlling glycation and improving the emulsifying properties of SPI.

This study evaluated the effects of different drying techniques on the physicochemical properties of Pleurotus citrinopileatus Singer (P. citrinopileatus), focusing on the ergothioneine (EGT) contents. The P. citrinopileatus was subjected to natural ventilation drying (ND), freeze-drying (FD), and hot-air drying (HD). EGT was extracted using high-hydrostatic-pressure extraction (HHPE), and response surface methodology (RSM) was employed with four variables to optimize the extraction parameters. The crude EGT extract was purified by ultrafiltration and anion resin purification, and its antioxidant activity was investigated. The results showed that the ND method effectively disrupted mushroom tissues, promoting amino acid anabolism, thereby increasing the EGT content of mushrooms. Based on RSM, the optimum extracting conditions were pressure of 250 MPa, extraction time of 52 min, distilled water (dH₂O) as the extraction solvent, and a 1:10 liquid–solid ratio, which yielded the highest EGT content of 4.03 ± 0.01 mg/g d.w. UPLC-Q-TOF-MSE was performed to assess the purity of the samples (purity: 86.34 ± 3.52%), and MS² information of the main peak showed primary ions (m/z 230.1) and secondary cations (m/z 186.1050, m/z 127.0323) consistent with standard products. In addition, compared with ascorbic acid (VC), EGT showed strong free radical scavenging ability, especially for hydroxyl and ATBS radicals, at more than 5 mmol/L. These findings indicate that the extraction and purification methods used were optimal and suggest a possible synthetic path of EGT in P. citrinopileatus, which will help better explore the application of EGT.

Porcine intestinal mucosal proteins are novel animal proteins that contain large amounts of free amino acids and peptides. Although porcine intestinal mucosal proteins are widely used in animal nutrition, the peptide bioactivities of their enzymatic products are not yet fully understood. In the present study, we investigated the effect of porcine intestinal mucosal peptides (PIMP) on the RAW264.7 cell model of LPS-induced inflammation. The mRNA expression of inflammatory factors (interleukin 6, tumor necrosis factor-α, and interleukin-1β) and nitrous oxide levels were all measured by quantitative real-time PCR and cyclooxygenase-2 protein expression measured by Western blot. To investigate the modulating effect of PIMP and to establish a model of dextran sodium sulfate (DSS)-induced colitis in mice, we examined the effects of hematoxylin-eosin staining, myeloperoxidase levels, pro-inflammatory factor mRNA content, tight junction protein expression, and changes in intestinal flora. Nuclear factor κB pathway protein levels were also assessed by Western blot. PIMP has been shown in vitro to control inflammatory responses and prevent the activation of key associated signaling pathways. PIMP at doses of 100 and 400 mg/kg/day also alleviated intestinal inflammatory responses, reduced tissue damage caused by DSS, and improved intestinal barrier function. In addition, PIMP at 400 mg/kg/day successfully repaired the dysregulated gut microbiota and increased short-chain fatty acid levels. These findings suggest that PIMP may positively influence inflammatory responses and alleviate colitis. This study is the first to demonstrate the potential of PIMP as a functional food for the prevention and treatment of colitis.