Microfluidized hemp protein isolate: an effective stabilizer for high-internal-phase emulsions with improved oxidative stability.

BACKGROUND: Hemp protein isolates (HPIs), which provide a well-balanced profile of essential amino acids comparable to other high-quality proteins, have recently garnered significant attention. However, the underutilized functional attributes of HPIs have constrained their potential commercial applications within the food and agriculture field. This study advocates the utilization of dynamic-high-pressure-microfluidization (DHPM) for the production of stable high-internal-phase emulsions (HIPEs), offering an efficient approach to fully exploit the potential of HPI resources. RESULTS: The findings underscore the effectiveness of DHPM in producing HPI as a stabilizing agent for HIPEs with augmented antioxidant activity. Microfluidized HPI exhibited consistent adsorption and anchoring at the oil-water interface, resulting in the formation of a dense and compact layer. Concurrently, the compression of droplets within HIPEs gave rise to a polyhedral framework, conferring viscoelastic properties and a quasi-solid behavior to the emulsion. Remarkably, HIPEs stabilized by microfluidized HPI demonstrated superior oxidative and storage stability, attributable to the establishment of an antioxidative barrier by microfluidized HPI particles. CONCLUSION: This study presents an appealing approach for transforming liquid oils into solid-like fats using HPI particles, all without the need for surfactants. HIPEs stabilized by microfluidized HPI particles hold promise as emerging food ingredients for the development of emulsion-based formulations with enhanced oxidative stability, thereby finding application in the food and agricultural industries. © 2023 Society of Chemical Industry.

Fabrication of glycated yeast cell protein via Maillard reaction for delivery of curcumin: improved environmental stability, antioxidant activity, and bioaccessibility.

BACKGROUND: The application of curcumin (CUR) in the food industry is limited by its instability, hydrophobicity and low bioavailability. Yeast cell protein (YCP) is a by-product of spent brewer's yeast, which has the potential to deliver bioactive substances. However, the environmental stresses such as pH, salt and heat treatment has restricted its application in the food industry. Maillard reaction as a non-enzymatic browning reaction can improve protein stability under environmental stress. RESULTS: The CUR was successfully encapsulated into the hydrophobic core of YCP/glycated YCP (GYCP) and enhanced by hydrogen bonding, resulting in static fluorescence quenching of YCP/GYCP. The average diameter and dispersibility of GYPC-CUR nanocomplex were significantly improved after glucose glycation (121.40 nm versus 139.70 nm). Moreover, the encapsulation capacity of CUR was not influenced by glucose glycation. The oxidative stability and bioaccessibility of CUR in nanocomplexes were increased compared with free CUR, especially complexed with GYCP conjugates. CONCLUSION: Steric hindrance provided by glucose conjugation improved the enviriomental stability, oxidative activity and bioaccessibility of CUR in nanocomplexes. Thus, glucose-glycated YCP has potential application as a delivery carrier for hydrophobic compounds in functional foods. © 2022 Society of Chemical Industry.

Construction of Glycogen-Based Nanoparticles Loaded with Resveratrol for the Alleviation of High-Fat Diet-Induced Nonalcoholic Fatty Liver Disease.

The purpose of this study was to construct a glycogen (Gly)-based nanoparticle (NP) with liver-targeted and redox response to effectively deliver resveratrol (Res) for improving nonalcoholic fatty liver disease (NAFLD). Herein, Gly was modified using α-lipoic acid (α-LA) and lactobionic acid (Lac) to obtain an amphiphilic polymer (Gly-LA-Lac), which was self-assembled in water and then encapsulated in Res to form Res NPs with excellent stability. As expected, the Res NPs exhibited liver-targeted and redox response release behavior. In vitro cell studies demonstrated that the nanocarrier treatment enhanced the cellular uptake of Res and reduced oxidative stress and inflammatory factor levels. Meanwhile, the in vivo tests proved that the nanocarriers effectively reduced hepatic lipid accumulation and oxidative stress levels via regulating the TLR4/NF-κB signal pathway to improve liver damage in NAFLD mice. In conclusion, this study provides a promising strategy through the construction of Gly-based nanocarriers for the encapsulation of Res to effectively alleviate the process of NAFLD.

The effect of pH and amino acids on the formation of methylglyoxal in a glucose-amino acid model system.

BACKGROUND: Methylglyoxal (MGO) as a α-dicarbonyl compound not only affects food flavor and color but also contributes to the loss of nutrition and the generation of toxic compounds. The study was carried out using a glucose-amino acid model system with incubation at 120 °C to investigate the effect of amino acids and pH on the formation of MGO. MGO derivative (2-methylquinoxaline) was detected by high-performance liquid chromatography with a diode array detector. Changes in glucose, amino acids and products such as acetic acid were tested using high-performance anion exchange chromatography with an electrochemical detector or an electrical conductivity detector. RESULTS: Lysine and glycine had higher reactivity to form MGO and melanoidins than arginine and proline. More acetic acid was produced and a higher consumption of arginine was observed in glucose-arginine solution. Moreover, higher pH significantly accelerated the formation of MGO. CONCLUSION: Amino reactivity and pH were two important factors affecting the formation of MGO in the Maillard reaction. © 2016 Society of Chemical Industry.

Short communication: Amino trap column improves the separation of methylimidazoles, 5-hydroxymethyl-2-furaldehyde, and sugars in Maillard reaction.

A simultaneous analysis of methylimidazoles, reducing sugars, and 5-hydroxymethyl-2-furaldehyde in the Maillard reaction was improved by use of an amino trap column. Analysis was carried out by using high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) coupled with an amino trap column. The amino trap column was a useful tool to improve the separation of methylimidazoles, reducing sugars, and 5-hydroxymethyl-2-furaldehyde. This technique is useful for simultaneous analysis of methylimidazoles, reducing sugars, and 5-hydroxymethyl-2-furaldehyde in risk assessment for dairy products.

Theory and protocol of dual mode unity solid-phase microextraction.

The solid-phase microextraction (SPME) bias problem limits comprehensive analysis of volatile compounds in real samples. The study introduces dual mode unity solid-phase microextraction (DMU-SPME) as a novel SPME mode to achieve balanced extraction of both volatile and low-volatile compounds. The DMU-SPME method exhibits excellent linearity (R2 ≥ 0.994), low quantitation limits (0.12-240 µg/L), and notable stability (relative standard deviations below 20 % for both intra-day and inter-day analyses). In practical application to soy sauce, the DMU-SPME method identified a total of 107 compounds, encompassing all those detected by both headspace solid-phase microextraction (HS-SPME) and direct immersion solid-phase microextraction (DI-SPME). Theoretical insights indicate that DMU-SPME is less influenced by Kfs0 and Kfs in comparison to HS/DI-SPME, rendering it suitable for complex matrices containing both volatile and low-volatile compounds. In conclusion, DMU-SPME emerges as a highly effective extraction mode for analyzing volatile and low-volatile compounds in food, medical, and environmental samples.

Simultaneous analysis of Nε-(carboxymethyl)lysine, reducing sugars, and lysine during the dairy thermal process.

A new analytical method allowing the simultaneous quantification of Nε-(carboxymethyl)lysine (CML), lysine, and reducing sugars (glucose, lactose, and galactose) is described. It is based on high performance anion-exchange chromatography with pulsed amperometric electrochemical detection. This method demonstrated a low limit of quantification (0.385 to 0.866 mg/L), excellent linear correlation (R(2)>0.997), and desired calibration range (3.125 to 25 mg/L). In addition, lactose-lysine solutions containing sulfite (4 to 400 mmol/L) were heated at 110°C for 2h. The results showed that sulfite inhibited the formation of CML and promoted the consumption of reducing sugars and lysine in the Maillard reaction model. The method proved to be useful for simultaneous analysis of CML, lysine, and reducing sugars (glucose, galactose, and lactose) in the Maillard reaction system. Moreover, sulfite was an effective inhibitor of CML formation.

Short communication: possible mechanism for inhibiting the formation of polymers originated from 5-hydroxymethyl-2-furaldehyde by sulfite groups in the dairy thermal process.

5-Hydroxymethyl-2-furaldehyde can undergo polymerization to form high-molecular weight molecules via the Maillard reaction during dairy thermal treatment. In this study, the effect of sulfite group on polymer formation, especially in inhibiting the formation of high-molecular weight polymers has been described. Results showed that the sulfite group significantly inhibited the increase of polymer molecular weight via prevention of the polymerization of 5-hydroxymethyl-2-furaldehyde. The formation of an intermolecular dimer based on the glucose molecule through Schiff base cyclization can lead to a competitive reaction with 1,2-enolization to reduce 5-hydroxymethyl-2-furaldehyde formation, which might be another factor in reducing the formation of high-molecular weight polymers.

Balanced extraction of volatile and semi-volatile compounds by dynamic linked position unity solid-phase microextraction.

Although the compound profiles in extracts are linked to the solid-phase microextraction (SPME) position (headspace or liquid), a theoretical interpretation of this scenario has not yet been provided. In this study, the dynamic linked position unity (DLPU)-SPME is proposed as a method that allows balanced extraction of volatile and semi-volatile compounds. Furthermore, the pH, temperature, and salt were confirmed as the key factors affecting the extraction efficiency of DLPU-SPME. Theoretical calculations indicated that Kfs0Kfs is a key factor directly indicating the SPME extraction position (Kfs0Kfs > 1, headspace; Kfs0Kfs = 1, any position; Kfs0Kfs < 1, in liquid), while the target analytes determined that VhKhs+VsVeKfhKhs regulates the effect of the extraction position on the extracted amount. The proposed DLPU-SPME method containing both extraction positions (i.e., headspace and liquid) can simultaneously extract volatile and semi-volatile compounds, thus avoiding extraction bias.

Untargeted analysis of microbial metabolites and unsaturated fatty acids in salmon via hydrophilic-lipophilic balanced solid-phase microextraction arrow.

The ability to detect spoilage and the nutrient content of salmon is critical for ensuring food safety and determining market value. In this paper, we document the development of a hydrophilic-lipophilic balanced solid-phase microextraction arrow that offers better extraction performance than two other commercial devices. The devices were also compared using two operational models: headspace microextraction and direct immersion. The multidimensional statistical analysis and heatmap analysis for the headspace microextractions showed that the content levels of volatile metabolites including hydrocarbons, alcohols, ketones, acids, amino acids, and ethers increased with longer storage times, indicating an increase in the activity of spoilage-associated bacteria, such as gram-negative bacteria. For the direct immersion tests, important nutrients, including lipids, sterols, and squalene, were directly extracted from the salmon fillets with high efficiency. Thus, the developed method provides a simple and easy time-domain monitoring strategy for testing the freshness and quality of salmon for consumers.

Fabrication of flavour oil high internal phase emulsions by casein/pectin hybrid particles: 3D printing performance.

In this study, three-dimensional (3D) printable oil/water (O/W) high-internal-phase emulsions (HIPEs) (internal phase fraction = 75%) were fabricated using casein (3% w/v)/pectin (1-5% w/v) hybrid particles with flavour oil. The morphologies of the HIPEs, revealed by confocal laser scanning microscopy (CLSM) and cryo-scanning electron microscopy (cryo-SEM), indicated that the casein/pectin hybrid particles were mainly distributed on the interface of oil droplets. Additionally, the results of rheological and gel-strength measurements indicated that the viscosity (ranging from 1316.51-0.21 to 4301.84-0.79 Pa.s) of HIPEs increased with increasing pectin content (from 0% to 4% w/v), and the gel strength of printed HIPEs increased (from 10.37 to 21.19 g) with increasing pectin (from 1% to 5% w/v). The developed HIPEs were applied for 3D printing and the thus-printed objects could adequately maintain the designed shape and structure. The developed 3D printable HIPEs have excellent potential applications in the food, medical, and cosmetic industries.

Model studies on the formation of 2-vinylpyrazine and 2-vinyl-6-methylpyrazine in Maillard-type reactions.

Vinylpyrazine compounds are widely present in foods, especially in hot-processed foods, as a class of flavor compounds; however, their formation mechanism in food systems is still unclear. Therefore, in this study, 2-vinylpyrazine and 2-vinyl-6-methylpyrazine were identified in the Maillard model reaction of d-glucose and glycine. The Maillard model reaction of glucose-glycine was constructed to explore the effects of reaction parameters on vinylpyrazines and the related products. The Maillard reaction of [U-13C6] glucose and glycine was established, and alkylpyrazines and formaldehyde were determined via isotope tracing technique as the precursors of vinylpyrazines. The formation of vinylpyrazines was verified by building a model reaction between alkylpyrazines and formaldehyde. The H/D exchange experiment confirmed that the active site of alkylpyrazines was on the methyl group, which was the reaction site for the condensation reaction of alkylpyrazines with formaldehyde. Results suggest that vinylpyrazines are formed by the condensation reaction of alkylpyrazines and formaldehyde.

Determination of selected volatile terpenes in fish samples via solid phase microextraction arrow coupled with GC-MS.

A high-efficiency enrichment method is required for determination of trace-level volatile terpenes in fish tissue, since the presence of such compounds in fish at elevated levels may induce bad sensory acceptance of fish meat, thus degrading its customer acceptance and consequently, its market value. In this study, a solid-phase microextraction (SPME) arrow configuration using a thick sorbent coating (120 µm, PDMS/CWR) was applied to enrich selected terpenes, namely α-pinene, limonene, linalool, and citronellol, in fish tissue (Oreochromis niloticus). Due to the thicker coating of the SPME arrow, a longer extraction time of 60 min was required to reach equilibrium extraction in comparison to the traditional fiber configuration. SPME conditions such as extraction temperature (60 °C), desorption temperature (250 °C), and salt effect (10% NaCl) were optimized for the developed application using the arrow configuration. The developed method exhibited good linearity at a concentration range of 5.0-500.0 µg L-1 for α-pinene and limonene, and 50.0-500.0 µg L-1 for linalool and citronellol. In addition, the coefficients of determination (R2) for all terpenes ranged from 0.9990 to 0.9999. The developed method was shown to be robust with good inter-day reproducibility in the range of 3.6-8.3%. Method sensitivity was assessed in terms of limits of detection (LODs) and limits of quantification (LOQs), with higher sensitivity achieved for α-pinene and limonene (LODs of 1.7 µg L-1) in comparison to linalool (LOD, 5.0 µg L-1) and citronellol (LOD, 17.0 µg L-1). Theoretical calculations verified that the increased coating thickness afforded by the arrow configuration can enable higher method sensitivity and widen the range of detected compounds for the headspace SPME.

Reinvestigation of 2-acetylthiazole formation pathways in the Maillard reaction.

2-Acetylthiazole possesses a nutty, cereal-like and popcorn-like aroma and a low odor threshold, and this compound has been identified in some processed foods, while the formation pathway of 2-acetylthiazole has not been clearly elucidated. Here, a model reaction of d-glucose and l-cysteine was constructed to investigate the formation pathway of 2-acetylthiazole. l-Cysteine, d-glucose and the corresponding intermediates, namely, dicarbonyl compounds (DCs), were involved in the formation of 2-acetylthiazole and detected by high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS), high-performance ion chromatography (HPIC) and HPLC, respectively. The carbon module labeling (CAMOLA) technique revealed that the C-4 and C-5 of 2-acetylthiazole were derived from the carbons of glucose. The potential of glyoxal, which is degraded by glucose, to form 2-acetylthiazole was revealed for the first time. A novel route to form 2-acetylthiazole by the reaction of glyoxal and methylglyoxal produced by d-glucose with H2S and NH3 produced by l-cysteine was proposed.

Improving the functional properties of bovine serum albumin-glucose conjugates in natural deep eutectic solvents.

Glycation between target proteins and saccharides is time-consuming or requires high temperatures. Here, a promising reaction medium, natural deep eutectic solvents (NADES), for glucose glycation with bovine serum albumin (BSA) was applied to improve the grafting of glucose-glycated BSA by shifting reaction equilibrium. Two types of glucose-glycated BSA products were prepared using NADES and water systems. SDS-PAGE and MALDI-TOF-MS revealed that BSA and glucose were covalently bonded. Compared with in water system, glycated BSA products in NADES system had more -OH groups, more disordered secondary structures, lower intrinsic fluorescence intensity, and higher ultraviolet-visible absorption. Lower surface hydrophobicity (1100 versus 1356), higher emulsifying activity index (66.17 versus 46.49 m2/g), higher emulsion stability index (79.62 versus 63.61%), and lesser free sulfhydryl (8.07 versus 8.98 µmol/g) groups were obtained with NADES system than with water system. The results suggest that NADES is a suitable alternative reaction medium for promoting the glycation of BSA.

Ultrasound pre-fractured casein and in-situ formation of high internal phase emulsions.

Traditional preparation of protein particles is usually complex and tedious, which is a major issue in the development of Pickering high internal phase emulsions (HIPEs). In this study, a facile and in-situ method for the preparation of food-grade Pickering HIPEs was developed using ultrasound pre-fractured casein flocs. The ultrasonic-treated casein protein and resulting Pickering HIPEs were characterised using particle size distribution, confocal laser scanning microscopy (CLSM), cryo-SEM, and rheological measurement. The results indicated that pH values of casein and ultrasonic power level were key parameters for casein protein dispersion into nanoparticles to form o/w Pickering HIPEs. In optimal conditions, the hexagons of emulsion droplets were close together, and the emulsions formed with ultrasonic caseins exhibited gel-like behaviour. Additionally, ultrasonic microscale-sized caseins (about 25 µm) disappeared upon the use of high speed homogenisation during the formation of HIPEs, while the chemical distribution revealed by confocal laser scanning microscopy indicated that the dispersive nanoparticles from casein proteins were evidently absorbed on the interface of HIPEs (cryo-SEM). These findings prove that ultrasound is an effective tool to loosen casein flocs to induce the in-situ formation of stabilised Pickering HIPEs. Overall, this work provides a green and facile route to convert edible oil into a soft solid, which has great potential for applications in biomedical materials, 3D printing technology, and various cosmetics.

Dispersive solid-phase extraction and dispersive liquid-liquid microextraction for the determination of flavor enhancers in ready-to-eat seafood by HPLC-PDA.

The dispersion solid-phase microextraction (DSPE) combined with dispersion liquid-liquid microextraction (DLLME) was developed as a rapid, simple and effective pretreatment method for the determination of flavor enhancers (maltol, ethyl maltol, vanillin, methyl vanillin, ethyl vanillin) of ready-to-eat seafood products (dried squid, baked squid, fried fish, steamed abalone). Under the optimized DSPE-DLLME method, the developed method exhibited low limits of quantitation (0.20-0.50 µg g-1) and excellent linearity (R2 ≥ 0.995). The recoveries of flavor enhancers in the actual samples were 83.7%-114.9%. Compared with traditional pretreatment methods, the developed DSPE-DLLME method was rapid (17 min) and easy to determine the flavor enhancers by high performance liquid chromatography with photodiode array detector (HPLC-PDA). In the actual samples, creamy compounds such as vanillin, methyl vanillin and ethyl vanillin were hardly found. However, the flavor compounds produced by thermal reactions such as maltol (except for dried squid 3) and ethyl maltol were present in all samples.

Effect of alkyl distribution in pyrazine on pyrazine flavor release in bovine serum albumin solution.

The flavor release mechanism related to the interaction of aroma compounds with proteins is still unclear. In this study, the interaction of protein with pyrazine homologues, such as 2-methylpyrazine (MP), 2,5-dimethylpyrazine (DP), 2,3,5-trimethylpyrazine (TRP) and 2,3,5,6-tetramethylpyrazine (TEP), was investigated to elucidate the effect of alkyl distribution in a pyrazine ring on its flavor release in bovine serum albumin (BSA) solution (pH 7.4). The results of SPME-GC-MS indicated that methyl distribution in a pyrazine ring significantly affected its release from BSA solution. The pyrazines released from BSA solution with an increasing order of MP, DP, TRP and TEP. The inhibition mechanism of alkyl-pyrazine release was further elucidated by the interaction between alkyl-pyrazines and BSA using multiple spectroscopic methods. The non-covalent interaction between alkyl-pyrazines and BSA was confirmed as the main interaction force by the value of the bimolecular quenching constant (K q > 2 × 1010 L mol-1 s-1). A decrease in the hydrophobicity of the microenvironment between the alkyl-pyrazine and BSA was detected by synchronous fluorescence spectra, which revealed that alkyl-pyrazines were mainly bound on the sites of tyrosine and tryptophan in BSA. The UV-vis absorption spectra and circular dichromatic (CD) spectrum revealed that alkyl-pyrazines could induce polarity and conformation change of BSA. The above results indicated that the structure of the flavor homologues can affect their release in food matrices.

Coated direct inlet probe coupled with atmospheric-pressure chemical ionization and high-resolution mass spectrometry for fast quantitation of target analytes.

The coated direct inlet probe (CDIP) is a new laboratory-made low-cost technology developed from a direct inlet probe (DIP), which has the advantage of quick enrichment/cleanup of an analyte from liquid samples. A capillary probe is coated with hydroxy-terminated polydimethylsiloxane (OH-PDMS), divinylbenzene (DVB), and ß-cyclodextrin (ß-CD) by a sol-gel method. This probe can be directly coupled with a commercialized atmospheric-pressure chemical ionization (APCI) ion source and high-resolution mass spectrometry, which are widely applicable, reliable, and durable. The ability to perform quantitative analyses with the use of a stable-isotope-labeled internal standard (SIL-IS) was tested by using different concentrations of acenaphthylene (ACY), acenaphthene (ACP), fluorene (FLR), fluoranthene (FLT), phenanthrene (PHE), and benzo[a]pyrene (B[a]P). Calibration curves with a coefficient of determination of R2 ≥ 0.9982 for different polycyclic aromatic hydrocarbons (PAHs) were obtained. A limit of detection (LOD) of 0.008-0.04 ng mL-1 for PAHs was determined. The entire workflow is solvent-free and can be completed in less than 5 min, which demonstrates the advantages of this technique for quantitative analysis.

Simultaneous quantification of free amino acids and 5'-nucleotides in shiitake mushrooms by stable isotope labeling-LC-MS/MS analysis.

Evaluation of free amino acids (FAAs) and nucleotides in various food matrices has been a widely studied topic in recent years. Here, a fast and efficient strategy for the simultaneous analysis of 20 FAAs and six 5'-nucleotides, using stable isotope labeling-liquid chromatography coupled with tandem mass spectrometry (SIL-LC-MS/MS) is proposed. The method was validated with respect to selectivity, linearity, limits of detection (LOD) and quantification (LOQ), recovery, precision, and stability. LOQs of most FFAs were lower than 1 ng/mL, and 5'-nucleotides were in the range of 5-20 ng/mL. FAAs and 5'-nucleotides in ten shiitake mushrooms from different cultivate areas were further analyzed. Results showed that the contents of cytidine 5'-monophosphate, adenosine 5'-monophosphate, lysine, threonine, arginine were significantly different. Principal component analysis showed clear discrimination of origins, seasons and species. Thus, the proposed method is suitable for the fast discrimination of species and geographical origins of shiitake mushrooms.