Effect of pH on the emulsifying performance of protein-polysaccharide complexes.

BACKGROUND: Protein-polysaccharide complexes have been successfully used for emulsion stabilization. However, it is unclear how the complex's surface charge influences aggregation stability and coalescence stability of emulsions, and whether a low charged interfacial film can still maintain the coalescence stability of oil droplets. In the present study, the effects of pH (around the pI of protein) on the aggregation and coalescence stability of emulsions were investigated. RESULTS: Whey protein isolate (WPI) and peach gum polysaccharides (PGP) complexes (WPI-PGP complexes) were synthesized at pH 3, 4 and 5. Their sizes were 598, 274 and 183 nm, respectively, and their ζ-potentials were +2.9, -8.6 and -22.8 mV, respectively. Interface rheological experiments showed that WPI-PGP complex at pH 3 had the lowest interfacial tension, and formed the softest film compared to the complexes at pH 4 and 5. Microfluidic experiments showed that all WPI-PGP complexes were able to stabilize droplets against coalescence within short timescales (milliseconds). At pH 3, no coalescence was observed even under conditions where the continuous phase flow influenced the shape of oil droplets (from spheres to ellipsoids). At pH 4 and 5, the model emulsions were stable over 16 days of storage, extensive aggregation and creaming occurred at pH 3 after 8 days. Importantly, no coalescence took place. CONCLUSION: The present study confirmed that the aggregation stability of the emulsions was mainly determined by the surface charge of the complex, whereas the coalescence stability of emulsions is expectedly determined by steric repulsion, providing new insights into how to prepare stable food emulsions. © 2024 Society of Chemical Industry.

Camellia Oleifera shells derived nano cellulose crystals conjugated with gallic acid as a sustainable Pickering emulsion stabilizer.

Lately, emulsions with low-fat and natural stabilizers are predominant. This study extracted the nano cellulose crystals (NCs) from Camellia Oleifera shells, and their gallic acid (GA) conjugates were synthesized by free-radical grafting. Pickering emulsions were prepared using NCs 1 %, 1.5 %, 2.5 %, and gallic acid conjugates NC-GA1, NC-GA2, and NC-GA3 as stabilizers. The obtained nano cellulose crystals exhibited 18-25 nm, -40.01 ±â€¯2.45 size, and zeta potential, respectively. The contact angle of 83.4° was exhibited by NC-GA3 conjugates. The rheological, interfacial, and microstructural properties and stability of the Pickering emulsion were explored. NC-GA3 displayed the highest absorption content of 79.12 %. Interfacial tension was drastically reduced with increasing GA concentration in NC-GA conjugates. Rheological properties suggested that the low-fat NC-GA emulsions showed a viscoelastic behavior, increased viscosity, gel-like structure, and increased antioxidant properties. Moreover, NC-GA3 displayed reduced droplet size and improved emulsion temperature and storage stability (28 days) against phase separation. POV and TBARS values were reduced with the NC-GA3 (P < 0.05). This work confirmed that grafting phenolic compounds on NCs could enhance bioactive properties, which can be used in developing low-fat functional foods. NC-GA conjugates can potentially fulfill the increasing demand for sustainable, healthy, and low-fat foods.

Nucleic Acid Plate Culture: Label-Free and Naked-Eye-Based Digital Loop-Mediated Isothermal Amplification in Hydrogel with Machine Learning.

Digital nucleic acid amplification enables the absolute quantification of single molecules. However, due to the ultrasmall reaction volume in the digital system (i.e., short light path), most digital systems are limited to fluorescence signals, while label-free and naked-eye readout remain challenging. In this work, we report a digital nucleic acid plate culture method for label-free, ultrasimple, and naked-eye nucleic acid analysis. As simple as the bacteria culture, the nanoconfined digital loop-mediated isothermal amplification was performed by using polyacrylamide (PAM) hydrogel as the amplification matrix. The nanoconfinement of PAM hydrogel with an ionic polymer chain can remarkably accelerate the amplification of target nucleic acids and the growth of inorganic byproducts, namely, magnesium pyrophosphate particles (MPPs). Compared to that in aqueous solutions, MPPs trapped in the hydrogel with enhanced light scattering characteristics are clearly visible to the naked eye, forming white "colony" spots that can be simply counted in a label-free and instrument-free manner. The MPPs can also be photographed by a smartphone and automatically counted by a machine-learning algorithm to realize the absolute quantification of antibiotic-resistant pathogens in diverse real samples.

Valorization and protection of anthocyanins from strawberries (Fragaria×ananassa Duch.) by acidified natural deep eutectic solvent based on intermolecular interaction.

This study introduces an innovative approach for the valorization and protection of anthocyanins from 'Benihoppe' strawberry (Fragaria × ananassa Duch.) based on acidified natural deep eutectic solvent (NADES). Choline chloride-citric acid (ChCl-CA, 1:1) was selected and acidified to enhance the valorization and protection of anthocyanins through hydrogen bond. The optimal conditions (ultrasonic power of 318 W, extraction temperature of 61 °C, liquid-to-solid ratio of 33 mL/g, ultrasonic time of 19 min), yielded the highest anthocyanins of 1428.34 µg CGE/g DW. UPLC-Triple-TOF/MS identified six anthocyanins in acidified ChCl-CA extract. Stability tests indicated that acidified ChCl-CA significantly increased storage stability of anthocyanins in high temperature and light treatments. Molecular dynamics results showed that acidified ChCl-CA system possessed a larger diffusion coefficient (0.05 m2/s), hydrogen bond number (145) and hydrogen bond lifetime (4.38 ps) with a reduced intermolecular interaction energy (-1329.74 kcal/mol), thereby efficiently valorizing and protecting anthocyanins from strawberries.

The uncharted territory of NAD+-capped RNA.

The critical redox cofactor NAD+ was recently reported to serve as an RNA cap in both eukaryotes and prokaryotes. However, its reversible regulation and biological functions remain unclear. Here, we provide insights into its discovery, capping and decapping mechanisms, for further discovery of their potential functional implications.

Changes in properties of human milk under different conditions of frozen storage.

Human milk is the best source of nutrition for infants. Lower freezing temperatures and faster freezing rates allow for better preservation of human milk. However, research on the freezing conditions of human milk is limited. This study investigated the effectiveness of quick freezing and suitable freezing conditions for home preservation. Human milk was stored under different freezing conditions (-18 °C, -18 °C quick freezing, -30 °C, -40 °C, -60 °C, and - 80 °C) for 30, 60, and 90 days and then evaluated for changes in the microbial counts, bioactive protein, and lipid. The results showed that the total aerobic bacterial and Bifidobacteria counts in human milk after storage at freezing temperatures of - 30 °C and lower were closer to those of fresh human milk compared to - 18 °C. Furthermore, the lysozyme loss, lipid hydrolysis degree, and volatile organic compound production were lower. However, -18 °C quick freezing storage was not markedly different from -18 °C in maintaining human milk quality. Based on the results, for household and environmental reasons, the recommended temperature for storing human milk is suggested as -30 °C.

Construction of self-assembled nano cellulose crystals/chitosan nanobubbles composite hydrogel with improved gallic acid release property.

Hydrogels are of great significance in the field of bioactive delivery. This study designed the self-assembly of gallic acid-loaded nano cellulose crystals/chitosan (NC/CS) hydrogels via Nano bubbles (NBs). NC/CS NBs 4:2 hydrogels improved the mechanical properties compared to those without NBs. The hardness of NC/CS (4:2) NBs hydrogels was greatly enhanced by 1.15 ± 0.05. The water-holding and swelling behavior can be tuned at different ratios. NC/CS NBs (4:2) showed the electrostatic interaction analyzed by FTIR, XRD, and XPS. SEM results displayed smoother and smaller pores along dense networks promoted by NBs. The antioxidant activity of hydrogels was increased by adding NBs (P < 0.05). In vitro and vivo release activity of gallic acid was higher in simulated intestinal fluid (SIF) at 4:2, depicting the controlled release mechanism. Thus, current work revealed that NBs and low concentrations of NC can be self-assembled with chitosan chains, producing a highly compact hydrogel structure.

Development of a chitosan/pectin-based multi-active food packaging with both UV and microbial defense functions for effectively preserving of strawberry.

Multi-active food packaging was prepared for strawberry fruit preservation where epigallocatechin gallate (EGCG)-containing pectin matrix and natamycin (NATA)-containing chitosan (CS) matrix were utilized to complete LBL electrostatic self-assembly. The results showed that the physicochemical properties of the multi-active packaging were closely related to the addition of NATA and EGCG. It was found that NATA and EGCG were embedded in the CS/pectin matrix through intermolecular hydrogen bonding interactions. The CN/PE 15 % multi-active films prepared based on the spectral stacking theory formed a barrier to UV light in the outer layer, exhibited excellent NATA protection under UV light exposure conditions at different times, and provided long-lasting and sustained bacterial inhibition in the inner layer. In addition, the CN/PE 15 % multi-active packaging extended the shelf life of strawberry at room temperature compared with the control samples. In conclusion, the developed CN/PE 15 % packaging provided potential applications for multi-active food packaging materials.

Bioactive Components and Biological Activities of Crocus sativus L. Byproducts: A Comprehensive Review.

The production of saffron spice results in numerous byproducts, as only 15 g of spice can be produced from 1 kg of flowers, indicating that over 90% of the saffron flower material is eventually discarded as waste. In view of this, the paper reviews current knowledge on the natural active components in saffron byproducts and their biological activities, aiming to lay a theoretical and scientific foundation for the further utilization. Saffron byproducts contain a variety of phytochemical components, such as flavonoids, anthocyanins, carotenoids, phenolic acids, monoterpenoids, alkaloids, glycosides, and saponins. The activities of saffron byproducts and their mechanisms are also discussed in detail here.

Hydrogel Digital LAMP with Suppressed Nonspecific Amplification for Rapid Diagnostics of Fungal Disease in Fresh Fruits.

Fungal disease, mainly caused by Alternaria alternata infection, can generate severe economic losses and health hazards. However, rapid nucleic acid test without nonspecific reaction still remains challenging. Here, we reported the hydrogel digital loop-mediated isothermal amplification (HdLAMP) with suppressed nonspecific amplification for rapid diagnosis of fungi in fresh fruits. The introduction of hydrogel offered a simple platform to achieve absolute quantification. By breaking the 3'end G-C anchor, the nonspecific amplification of primers could be suppressed, while the specific positive reaction in HdLAMP was not affected. This method could be applied for A. alternata detection in 9 min with excellent performances in speed, specificity, reproducibility, sensitivity, and detection limit down to a single copy. Finally, the real diseased jujubes during postharvest storage were successfully diagnosed as an A. alternata infection. HdLAMP promotes the molecular diagnosis of fungal diseases and broadens the application of hydrogels in the agricultural and food industry.

How to effectively and greenly prepare multi-scale structural starch nanoparticles for strengthening gelatin film (ultrasound-Fenton system).

Ultrasound (US) assisted with Fenton (US-Fenton) reaction was developed to efficiently and greenly prepare starch nanoparticles (SNPs) that were employed as nanofillers to enhance gelatin (G) film properties. Compared to Fenton reaction alone, US-Fenton reaction significantly improved preparation efficiency and dispersion of SNPs (p < 0.05). An optimal US-Fenton reaction parameter (300 mM H2O2, ascorbic acid 55 mM, US 45 min) was found to prepare SNPs with uniform sizes (50-90 nm) and low molecular weight (Mn 7.91 × 105 Da). The XRD, FT-IR, and SAXS analysis revealed that the US-Fenton reaction degraded the amorphous and crystalline zones of starch from top to down, leading to the collapse of the original layered structure starch and the progressive formation of SNPs. The different sizes of SNPs were selected to prepare the composite films. The G-SNP3 film (with 50-90 nm SNPs) showed the most outstanding UV blocking, tensile, and barrier properties. Especially, the tensile strength of G-5%SNP3 film (containing 5 % SNPs) increased by 156 % and 6 % over that of G film and G-5%SNP2 film (containing 5%SNPs with 100-180 nm), respectively. Therefore, the nanomaterial was promisingly prepared by the US-Fenton system and provided a strategy for designing and producing nanocomposite films.

An efficient approach for extraction of polysaccharide from abalone (Haliotis Discus Hannai Ino) viscera by natural deep eutectic solvent.

In this study, a natural deep eutectic solvent (NADES) was proposed for the ultrasonic-assisted extraction of polysaccharides from abalone (Haliotis Discus Hannai Ino) viscera. Eleven NADESs were employed for abalone viscera polysaccharide (AVP) extraction. NADES, composed of choline chloride and ethylene glycol in a molar ratio 1: 3 had the highest extraction efficiency. The optimal extraction conditions were obtained using a four-factor, three-level Box-Behnken design and specific response surface methodology. The maximum predicted polysaccharide yield was 17.32 %. Fick's second law was fitted to the extraction process of AVP by ultrasonic-assisted NADES based on a high linear correlation (R2 ≥ 0.9). The extraction rate constants (k), diffusion coefficients (Du) and half-lives (t1/2) were calculated. Compared to the polysaccharides prepared by the conventional method, the polysaccharides extracted by NADES had a higher sugar content, lower molecular weight, more glucuronic acid, and stronger antioxidant capacity. Overall, the NADES extraction method established in this research can become a strategy for the preparation of high-purity and highly bioactive abalone viscera polysaccharides, which has implications for the exploitation and application of marine food byproduct resources.

Synthesis and characterization of fucoidan/chitosan-coated nanoliposomes for enhanced stability and oral bioavailability of hydrophilic catechin and hydrophobic juglone.

This study aimed to improve the thermodynamic performance of nanoliposomes (NLs) using fucoidan (F) as the second-layer coating biopolymer along with chitosan (CS), to control the delivery and bioavailability of catechin (C) and juglone (J). The stabilized liposomal carrier of F/CS-conjugated JC-NL (F-CS-JC-NL) was developed with optimum concentrations of CS (0.09 wt%) and F (0.10 wt%), with the highest encapsulation efficiency of juglone (95.47%) and catechin (90.88%). Physicochemical characterization revealed that F-CS-JC-NL disclosed improved stability under different pH and ionic strengths, with the maximum juglone/catechin retention under thermal, oxidative and storage conditions. In vitro digestion revealed that NL double-coating (F-CS-JC-NL) significantly reduced compound leakage in the gastrointestinal tract, providing a controlled release and better bioavailability of juglone/catechin compared to CS-JC-NL and JC-NL. Conclusively, this study provides a novel NL-based delivery carrier with enhanced physicochemical stability and controlled release that might have promising use in delivering functional ingredients.

Novel insight into the role of sulfur dioxide in fruits and vegetables: Chemical interactions, biological activity, metabolism, applications, and safety.

Sulfur dioxide (SO2) are a category of chemical compounds widely used as additives in food industry. So far, the use of SO2 in fruit and vegetable industry has been indispensable although its safety concerns have been controversial. This article comprehensively reviews the chemical interactions of SO2 with the components of fruit and vegetable products, elaborates its mechanism of antimicrobial, anti-browning, and antioxidation, discusses its roles in regulation of sulfur metabolism, reactive oxygen species (ROS)/redox, resistance induction, and quality maintenance in fruits and vegetables, summarizes the application technology of SO2 and its safety in human (absorption, metabolism, toxicity, regulation), and emphasizes the intrinsic metabolism of SO2 and its consequences for the postharvest physiology and safety of fresh fruits and vegetables. In order to fully understand the benefits and risks of SO2, more research is needed to evaluate the molecular mechanisms of SO2 metabolism in the cells and tissues of fruits and vegetables, and to uncover the interaction mechanisms between SO2 and the components of fruits and vegetables as well as the efficacy and safety of bound SO2. This review has important guiding significance for adjusting an applicable definition of maximum residue limit of SO2 in food.

The journey of prochloraz pesticide in Citrus sinensis: Residual distribution, impact on transcriptomic profiling and reduction by plasma-activated water.

Prochloraz (PTIC) is a hazardous fungicide used worldwide on agricultural produce despite concerns about potential impacts on human health and environmental pollution. The residue of PTIC and its metabolite 2,4,6-trichlorophenol (2,4,6-TCP) in fresh produce has largely not been clarified. Herein, we address this research gap by examining residues of PTIC and 2,4,6-TCP in fruit of Citrus sinensis through a typical storage period. PTIC residue in the exocarp and mesocarp peaked on days 7 and 14, respectively, while 2,4,6-TCP residue gradually increased throughout storage period. Based upon gas chromatography-mass spectrometry and RNA-sequencing analysis, we reported the potential impact of residual PTIC on endogenous terpene production, and identified 11 DEGs encoding enzymes involved in terpene biosynthesis in Citrus sinensis. Additionally, we investigated both the reduction efficacy (max: 58.93%) of plasma-activated water in citrus exocarp and the minimal impact on quality attributes of citrus mesocarp. The present study not only sheds light on the residual distribution of PTIC and its impact on endogenous metabolism in Citrus sinensis, but also further provides theoretical basis for potential approaches for efficiently reducing or eliminating pesticide residues.

Azacytidine-induced hypomethylation delays senescence and coloration in harvested strawberries by stimulating antioxidant enzymes and modulating abscisate metabolism to minimize anthocyanin overproduction.

DNA methylation is increasingly known to be essential for fruit ripening and senescence. Currently, 5-azacytidine (AZ) was selected as an effective demethylator and it successfully shaped the genomic hypomethylation in harvested strawberries. This was associated with the reprogramming of global gene expressions, which influenced downstream food traits. The alleviation of decay and softening, as well as the deceleration of soluble solid accumulation, were included. Coloration was also delayed as a result of the AZ-induced hypomethylation. Our examinations of anthocyanin biosynthesis and transport revealed that they were markedly minimized, which was probably involved with the decreased abscisate level and its weakened metabolism. Additionally, under AZ, the retarded postharvest senescence process was observed and it might be induced by the inhibited ROS accumulation accompanying the peroxidase and catalase activities alteration. Overall, these findings underlined the importance of methylation in strawberries and suggested the potential role of epigenetic regulators in the postharvest industry.

Sulfur dioxide maintains storage quality of table grape (Vitis vinifera cv 'Kyoho') by altering cuticular wax composition after simulated transportation.

The cuticular wax layer as a natural defensive barrier plays a key role in postharvest fruit quality maintenance. This study investigated the effects of simulated transport vibration (STV) on the berry quality and cuticular wax, and the ability of sulfur dioxide (SO2) to ameliorate STV damage in table grapes during cold storage. Results showed that STV damage accelerated the deterioration in grapes quality, and resulted in degradation and melting of cuticular wax, accompanied by a decrease in load of total wax, triterpenoids, fatty acids, alcohols, and olefins while an increase in alkanes and esters content during subsequent storage. However, SO2 effectively reversed the adverse impact of STV damage by increasing most wax fraction levels and corresponding genes expression, especially triterpenoids, although it had no apparent effect on wax structure. Overall, SO2 delayed the quality deterioration caused by vibration damage that occurs during transportation and storage by altering cuticular wax composition.

Ultrasensitive quantification of pathogens in milliliters of beverage by filtration-based digital LAMP.

The quantitative detection of pathogens in milliliters of beverage sample requires complex preprocessing. To achieve rapid and ultrasensitive quantification of pathogens in large volume food sample, we developed a filtration-based interfacial digital LAMP (idLAMP) system, which consists of a nanoporous membrane for filtration and nanoporous hydrogel for digital amplification. Digital counting of single bacteria at the membrane surface under nanoconfinement could be achieved. The idLAMP successfully accomplished the quantitative detection of Escherichia coli in 100 mL water samples within 30 min, with wide dynamic range from 0.09 to 900 cells/mL. This technique could also be well applied to the quantification of Escherichia coli and Salmonella typhi in real beverage samples (juice, tea drinks, carbonated drinks and alcoholic drinks) without tedious sample pretreatments. With facile operation, higher specificity and sensitivity and better end-point analysis capabilities, the system has great potential in quantitative counting of single bacteria in large-volume food samples.

An ultrafast electrochemical synthesis of Au@Ag core-shell nanoflowers as a SERS substrate for thiram detection in milk and juice.

An innovative bimetallic gold-silver core-shell nanoflowers (Au@Ag-CSNFs) SERS substrate has been synthesized by a facile electrochemical reduction process on an indium tin oxide (ITO) glass with a total fabrication time of 3 min. The proposed Au@Ag-CSNFs SERS substrate has been distributed evenly with numerous interstices and cavities between each branch, suggesting potential target trap sites and "hot spots". The Au@Ag-CSNFs administered good reproducibility of SERS signals collected from 140 random spots with a relative standard deviation and an enhancement factor of 13.62 % and 0.9 × 107, respectively. The substrate was further extended for the label-free SERS sensing of thiram residues with an ultra-low detection limit of 7.088 × 10-8 mol/L. The designed probe was further subjected to thiram determination in real milk and juice samples with satisfactory recoveries (91.76-109.40 %). The rapidly synthesized Au@Ag-CSNFs substrate can be extended for SERS sensing in a variety of hazards in food settings.

Nanoporous electrode with stable polydimethylsiloxane coating for direct electrochemical analysis of bisphenol A in complex wine media.

Direct electrochemical analysis of bisphenol A (BPA) in alcoholic drinks without proper sample preparation is a major challenge. The current work reports a nanoporous electrode design with ultrathin polydimethylsiloxane (PDMS) coating grafted on the top of an indium tin oxide (ITO) electrode with silica nanochannels membrane and cetyltrimethylammonium bromide micelles (SNCM), using a facile contact heating step. The proposed PDMS@SNCM/ITO electrode was subjected to direct ultra-trace detection of BPA in the linear range of 1.0-100.0 µM and detection limit of 0.23 µM, under optimized pH 8 and an accumulation time of 9.0 min. The analytical utility of the proposed method was checked in real wine samples for BPA detection with successful recovery percentages in the range from 95.20 ± 8.53 to 96.22 ± 10.00. The intrinsic hydrophobic features, exceptional stability, and sensitivity of the proposed electrode show potential for food safety surveillance in complex food matrices.