Food Technology and Biotechnology最新文献

Over the past two decades, the display of various recombinant proteins on the surfaces of microorganisms, particularly yeast, has garnered significant research attention. This method is rapid, simple and cost-effective, combining the biosynthesis and secretion of recombinant proteins with their immobilization on the host cell surface. Proteins synthesized using this technique are transported to the cell surface and incorporated into the cell wall through mild, native processes, avoiding aggressive chemical immobilization methods that often lead to a loss of physiological activity. Surface-displayed proteins are generally more stable and resistant to environmental changes than those in a solution. Depending on the promoter used, cells can continuously renew the recombinant protein on their surface or express it only under certain conditions. Additionally, cells carrying surface-displayed enzymes can be easily separated from the reaction mixture and reused multiple times. These enzymes can also catalyze reactions with substrates that cannot enter the cells, facilitating extracellular synthesis and simplifying product purification. However, the main obstacle to the industrial application of this method is often low efficiency, resulting in limited amounts of displayed protein. The efficiency depends on the processes that the protein undergoes on its way to the cell surface, following the same pathway as native secretory proteins: synthesis in the endoplasmic reticulum (ER), transport to the Golgi, and delivery to the cell surface via transport vesicles. Large amounts of secretory proteins can overload the ER, triggering the unfolded protein response (UPR) and endoplasmic reticulum-associated degradation (ERAD). Despite significant improvements for some proteins, a universal system for all recombinant proteins has yet to be developed. However, the complexity of protein processing and secretion pathways suggests that a single system improving productivity for all recombinant proteins is unlikely. Instead, several optimized systems tailored to specific protein structures may be necessary. This article provides an overview of the processes that recombinant proteins intended for surface display undergo on their way to the cell surface in the endoplasmic reticulum and represent a crucial bottleneck for the successful immobilization of recombinant proteins at the cell surface.

The increasing demand for sustainable alternatives to fossil-derived fuels and plastics has intensified research into microbial platforms that can convert abundant waste resources into valuable products. This review focuses on the emerging field of dual-target bioprocessing using oleaginous microorganisms to produce single-cell oils (SCOs) and polyhydroxyalkanoates (PHAs) from food waste. We discuss key microbial strains, their metabolic pathways, co-production capabilities and substrate preferences. Emphasis is placed on the use of food waste as a low-cost and carbon-rich feedstock, thereby enhancing both economic feasibility and environmental sustainability. We also analyze integrated bioprocess strategies developed to overcome existing challenges, such as yield optimization and metabolic bottlenecks. This dual-production platform addresses the principles of circular economy, facilitating the conversion of waste into high-value bioproducts.

Bee pollen is a nutrient-rich bee product and natural food supplement that contains proteins, vitamins, minerals and bioactive compounds, offering antioxidant, anti-inflammatory, immunostimulatory and antimicrobial activity. Numerous studies have confirmed the in vitro antimicrobial activity of both polyfloral and monofloral bee pollen. Monofloral bee pollen had a more stable chemical composition and more consistent sensory and biochemical properties, making it more suitable for various applications. This has led to a growing number of studies investigating its antimicrobial potential. Antimicrobial activity of bee pollen is influenced by natural factors such as the botanical and geographical origin, seasonal variation and beekeeping practices. The outcomes of in vitro testing also depend on choices related to extract preparation, solvent type, microbial strains and the method employed to measure antimicrobial activity. Another challenge is the limited bioavailability of bioactive compounds, restricted by the degradation-resistant outer layer of bee pollen, named the exine. The wall can be partially disrupted through processing methods that break it and enhance its nutritional and functional properties. This review provides a comprehensive overview of published studies on the antimicrobial activity of monofloral bee pollen. It summarizes the most frequently investigated botanical species and bacterial strains, highlighting those with the most promising antimicrobial results. Additionally, it examines the processing methods of pollen, comparing their effectiveness and the changes in antimicrobial activity before and after processing. The review identifies the plant species, solvents and methods that yield strong antimicrobial activity, emphasizing their potential in the broader effort to standardize high quality parameters for bee pollen.

Research background: Glycosyltransferases represent a large and diverse family of enzymes that catalyze the transfer of sugar residues to proteins and lipids, thereby regulating essential cellular processes such as protein quality control and cell wall biosynthesis. In yeast, protein O-mannosyltransferases and other glycosyltransferases are crucial for maintaining cell wall integrity. While the functions of many of these enzymes are well characterized, the role of some of them, such as Gmh5p, remains unknown. This study aims to elucidate the function of Gmh5p, a previously uncharacterized member of the GT34 glycosyltransferase family, in the context of protein and cell wall biosynthesis in Schizosaccharomyces pombe.

Experimental approach: To identify proteins and pathways compensating for reduced O-mannosylation, we performed a genetic screening for multicopy suppressors in a conditional lethal nmt81-oma2 ⁺ mutant background. The enzymatic activity of Gmh5p was biochemically characterized, and its functional homology to known mannosyltransferases was assessed through complementation experiments in Saccharomyces cerevisiae. In addition, the N-glycosylation status of model substrates was analyzed in gmh5Δ mutant strains.

Results and conclusions: Gmh5p was identified as a suppressor of O-mannosylation defects. Contrary to its predicted function, Gmh5p did not exhibit α-1,2-galactosyltransferase activity but instead showed mannosyltransferase activity. Expression of gmh5 ⁺ in S. cerevisiae mnn10Δ mutants restored hygromycin tolerance to near wild-type levels. Furthermore, N-glycosylation of model substrates was reduced in gmh5Δ mutants. These results demonstrate that Gmh5p is a mannosyltransferase involved in the outer chain elongation of N-linked glycans and functions as a homologue of Mnn10p.

Novelty and scientific contribution: This study provides the first functional characterization of Gmh5p as a mannosyltransferase of the GT34 family and demonstrates its role in N-glycan biosynthesis. Our findings expand the current understanding of the diversity and specificity of glycosyltransferases in eukaryotes and highlight their importance in cell wall biology.

Research background: Human milk is rich in bioactive molecules and beneficial bacteria that contribute to shaping the newborn's microbiota. In this study, we aim to evaluate lactic acid bacteria strains isolated from human milk of healthy Croatian women as potential functional starter cultures.

Experimental approach: In order to define novel potential probiotics for use in dairy products, eight strains of lactobacilli were analysed for their proteolytic, antimicrobial and antioxidant activity as well as their survival rate during freeze-drying.

Results and conclusions: Based on the results obtained, the exopolysaccharide-producing Limosilactobacillus fermentum MC1, the surface (S)-layer-producing Levilactobacillus brevis MB2 and the plantaricin-producing Lactiplantibacillus plantarum MB18 strains are candidates for the production of fermented dairy products with potential functional and nutritional relevance for the host. The selected strains exerted high casein degradation capacity, a broad spectrum of antimicrobial activity and a promising 2,2-diphenyl-1-picrylhydrazyl hydrate radical scavenging activity. They also fulfilled the primary technological criterion by having a high survival rate during freeze-drying.

Novelty and scientific contribution: The data presented emphasise the importance of human milk as a valuable source of lactic acid bacteria with unique technological and functional properties, which are important both as a basis for scientific research and for the development of novel starter cultures for functional products.

Research background: In the case of obesity, enlarged adipocytes cause an imbalance in lipid metabolism and increased oxidative stress, leading to excessive production of reactive oxygen species (ROS). ROS contribute to metabolic disorders such as inflammation and insulin resistance, further worsening lipid imbalance and promoting obesity-related diseases. Therefore, we investigated the benefits of Elsholtzia splendens, which simultaneously suppresses lipid accumulation and ROS.

Experimental approach: We determined the total flavonoid content of the extracts and identified the functional ingredients by HPLC. Cell viability and proliferation were evaluated in 3T3-L1 cells. The total lipid and triglyceride (TG) contents in 3T3-L1 cells and the nematode Caenorhabditis elegans were measured using Oil Red O staining and TG assay, respectively. A quantitative polymerase chain reaction (qPCR) analysis was performed to investigate the mRNA quantity and accumulated ROS in nematodes.

Results and conclusions: Apigenin was the major compound in the E. splendens extracts and was most abundant in the flower. The E. splendens flower extract did not show toxicity at concentrations of 25-100 μg/mL and had the highest apigenin content, thus we used the flower extract in the subsequent tests. E. splendens flower extract and apigenin inhibited total lipid and TG accumulation in 3T3-L1 cells and nematodes. These effects were attributed to the inhibition of peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα) expression, which are involved in adipocyte differentiation. In addition, the flower extract and apigenin induced the nuclear localization of DAF-16, which is involved in lipogenesis in nematodes. The flower extract and apigenin also inhibited ROS accumulation in nematodes.

Novelty and scientific contribution: Research on E. splendens has mainly focused on its cultivation and growth. Investigation of the effects of E. splendens on metabolic diseases, including obesity, has been limited and this study provides new insights. Our results suggest that E. splendens flower extract is a valuable material to inhibit lipid and ROS accumulation, and indicate that apigenin-rich functional plant materials should be considered as potential agents against obesity and related diseases.

Research background: The study investigates the use of chitin-glucan-based hydrogel (hereafter referred to as the hydrogel), obtained from Aspergillus niger mycelia grown on biological waste, to extend the shelf life of fresh Kashar cheese by reducing biochemical and microbiological degradation during storage.

Experimental approach: Biological waste, used as a medium for obtaining mycelium from A. niger, was collected weekly for four weeks from a hotel. Chitin-glucan nanofibre was produced from the mycelium using an alkaline method. The nanofibre was then freeze-thawed in an alkaline solvent system to form the hydrogel. To investigate the effect of the hydrogel on the shelf life of fresh Kashar cheese, hydrogel-coated cheese samples were analysed.

Results and conclusions: Fourier transform infrared spectroscopy (FTIR) analysis confirmed that the hydrogel consisted of chitin-glucan complex, while scanning electron microscope (SEM) images demonstrated its successful application as a surface coating. Coating with the hydrogel significantly increased the pH and mass loss of cheese samples compared to the control (distilled water, p≤0.05). Moisture loss rates were 8, 18 and 14 % for samples treated with water, hydrogel obtained by dissolving chitin-glucan complex in KOH (KOH-hydrogel) and NaOH (NaOH-hydrogel), respectively. Although the hydrogel did not significantly inhibit mould and yeast (p≥0.05), the KOH-hydrogel coating effectively reduced lactic acid bacteria (LAB) proliferation (p≤0.05), which is associated with souring. Additionally, reduced peroxide value (PV) in coated samples (p≤0.05) suggests improvements in oxidative stability. Hydrogel coatings also influenced the texture properties of the cheese: hardness, chewiness, adhesiveness and cohesiveness increased, while resilience and gumminess decreased (p≤0.05). Using zero-order kinetics, the shelf life of cheese was calculated based on peroxide formation, with deterioration defined at 2 mmol O₂ per kg of fat. The shelf life of uncoated cheese was estimated at 155 days, whereas it extended significantly to 555 days for cheese coated with either KOH- or NaOH-hydrogel. These results show the capacity of the hydrogels to reduce oxidative spoilage, thereby prolonging the cheese usability.

Novelty and scientific contribution: Study highlights that the hydrogel is sustainable, innovative edible coating with antioxidant properties, offering a promising approach for improving the quality and extending the shelf life of Kashar cheese. Future research could further optimize hydrogel formulations to enhance antimicrobial efficacy and explore their application in other high-moisture food products.

Research background: The global increase in population has led to a corresponding rise in the production of edible products and chemical preservatives. However, chemical preservatives are often associated with adverse health effects, highlighting the need to develop safer and more effective alternatives.

Experimental approach: This research evaluates the effectiveness and sensory acceptability of decolorized and undecolorized ethanol extracts of Leea aequata L. leaves as preservatives. The assessment involved applying the extracts to bread, jam and juice products, and conducting preliminary hedonic tests of bread and juice samples to determine sensory acceptability. The total plate count (TPC) and yeast and mould (YM) count were used to evaluate the effectiveness of preservation. Comparisons were made with a control without added preservatives and with products preserved using potassium sorbate.

Results and conclusions: Products treated with test extracts were as sensorially acceptable as those treated with potassium sorbate. The addition of the extracts was shown to have a preservative effect, as the TPC and YM counts were lower than in the control. Therefore, the test extracts have the potential to be developed as natural preservatives that could replace chemical variants such as potassium sorbate.

Novelty and scientific contribution: Decolorized and undecolorized ethanol extracts of Leea aequata L. leaves were shown for the first time as preservatives of edible products. The results of these tests are crucial for developing effective preservatives.

The 3D printing technique offers immense opportunities to manufacture foods tailored to individual preferences, with added benefits to address malnutrition. Malnutrition is a major public health issue that impedes the development of nations worldwide. Fortification with functional ingredients is a promising approach to combat this problem. However, consumer acceptance of fortified foods remains low due to their bland taste and unfamiliar formats. This situation has created the demand for customized, fortified products made with novel technologies like 3D printing. This review compiles research findings from the last 15 years on 3D printing in food manufacturing. It provides a detailed review on various technological options available for 3D printing, with emphasis on recent research related to functional food. Previous studies have demonstrated that 3D food printing is a highly promising novel technology capable of providing personalized nutrition. 3D food printers primarily use extrusion technology to create nutrient-rich food products in various 3D designs, meeting both the aesthetic and functional preferences of consumers. This technology is expected to revolutionize the functional food industry in the near future, due to its various applications.