The ability of peptide extracts obtained at different dry cured ham ripening stages to bind aroma compounds

Integration of volatile and non-volatile metabolite profile, and in vitro digestion reveals the differences between different preparation methods on physico-chemical and biological properties of Gastrodia elata

Gastrodia elata Blume (G. elata) is a traditional medicinal and edible plant whose quality is significantly influenced by post-harvest processing. To obtain an optimal post-harvest processing method for G. elata, this study employed sensory evaluation, scanning electron microscopy (SEM), gas chromatography-ion mobility spectrometry (GC-IMS), and non-targeted metabolomics, in conjunction with an in vitro digestion model, to assess the impact of different processing and drying methods on the quality of G. elata. The findings showed that the steam treatment followed by heat pump drying resulted in the highest levels of total phenols, total flavonoids, and polysaccharides in G. elata, and caused more pronounced damage to its microstructure. This treatment also maintained the highest antioxidant activities and optimal acetylcholinesterase (AChE) inhibition capacity throughout in vitro digestion, meanwhile, effectively eliminating the unpleasant odor and achieving the highest sensory scores. Furthermore, non-targeted metabolomic analysis revealed noteworthy alterations in the metabolite profile of G. elata, mainly related to purine metabolism and the biosynthesis of amino acids pathways. This study provides valuable insights into the post-harvest processing of G. elata.

Bioactive peptides in dry-cured ham: A comprehensive review of preparation methods, metabolic stability, safety, health benefits, and regulatory frameworks

Dry-cured hams contain abundant bioactive peptides with significant potential for the development of functional foods. However, the limited bioavailability of food-derived bioactive peptides has hindered their utilization in health food development. Moreover, there is insufficient regulatory information regarding bioactive peptides and related products globally. This review summarizes diverse bioactive peptides derived from dry-cured ham and by-products originating from various countries and regions. The bioactivity, preparation techniques, bioavailability, and metabolic stability of these bioactive peptides are described, as well as the legal and regulatory frameworks in various countries. The primary objectives of this review are to dig deeper into the functionality of dry-cured ham and provide theoretical support for the commercialization of bioactive peptides from food sources, especially the dry-cured ham.

The characteristic terpenes in sea cucumber soaked in star anise solution were characterized by HS-SPME-GC-MS and PCA analysis

The quality of sea cucumber is closely associated with its processing technology. In this study, the response surface methodology (RSM) was employed to optimize the thermal process conditions for seasoned sea cucumber, while gas chromatography-mass spectrometry (GC-MS) technique identified 25 characteristic compounds. Terpenes and their oxygen derivatives constituted approximately 70% of all compounds detected. Among these, trans-anethole emerged as the predominant volatile aroma compound in seasoned sea cucumber at a concentration of 39.99 ± 4.52 mg/g, followed by p-anisaldehyde, cis-anethole, linalool, estragole, and d-limonene. Principal component analysis (PCA) revealed that trans-anethole, cis-anethole, estragole, and d-limonene collectively contributed over 45.0% to the flavor profile of sea cucumber. This investigation provides an initial exploration into the alterations in volatile compounds within star anise-seasoned seasoned sea cucumber, thereby establishing a foundation for instant sea cucumbers' flavor processing.

Mechanism of Carbon Skeleton Formation of 2,3,5-Trimethylpyrazine via a Conversion Reaction between Methylglyoxal and Glyoxal

Maillard flavor compounds, such as 2,3,5-trimethylpyrazine, have been frequently identified in thermally processed food products, such as popcorn and peanuts. However, the origin of the carbon atoms in 2,3,5-trimethylpyrazine has not been clearly elucidated. Herein, a model reaction showed that precursor methylglyoxal and intermediates glyoxal and formaldehyde contributed to the formation of 2,3,5-trimethylpyrazine via a conversion reaction between methylglyoxal and glyoxal. In addition, carbon module labeling technology and model response validation experiments indicated that this transformation reaction between methylglyoxal and glyoxal brought formaldehyde into the methyl group carbon atoms of the 2,3,5-trimethylpyrazine ring. The proposed novel route provides a new perspective for approaches to control the formation of flavor compounds, such as 2,3,5-trimethylpyrazine.

Analysis of Volatile Compounds in Jinhua ham Using Three Extraction Methods Combined with Gas Chromatography-Time-of-Flight Mass Spectrometry

The volatile compounds in Jinhua ham samples after different aging times were characterized using solvent-assisted flavor evaporation (SAFE), solid-phase microextraction (SPME), and needle trap (NT) extraction methods combined with gas chromatography-time-of-flight mass spectrometry (GC-TOF/MS). Hundreds of aroma compounds were identified, including aldehydes, alcohols, ketones, furans, esters, acids, pyrazines, and sulfides. The results showed that NT extracted the greatest number of volatile compounds, whereas the extraction efficiency of SPME headspace adsorption was highest among the three sample preparation methods. Principal component analysis of SPME effectively distinguished the variation in the aroma of the Jinhua hams specific to aging time. Butyrolactone, 2,6-dimethylpyrazine, 2,3,5-trimethylpyrazine, phenylacetaldehyde, and acetic acid were considered as the main volatile compounds in the Jinhua ham samples at three years of aging. The results showed that SPME-GC-TOF/MS effectively discriminated among samples by age. By comparing the three extraction methods, this study provides a theoretical basis for the selection of extraction methods of volatile aroma compounds in Jinhua ham.

Changes in the Physical-Chemical Properties and Volatile Flavor Components of Dry-Cured Donkey Leg during Processing

In order to explore the quality variation and flavor formation of dry-cured donkey leg, the changes in physical−chemical composition, lipolytic, free amino acids content and volatile flavor compounds were investigated in this study. Six fresh, trimmed hind legs with average weight of 8.12 ± 0.8 kg were taken from male Dezhou donkeys slaughtered at the age of 24 months with the average live weight of 240 kg. The entire processing time was eight months long including six stages, specifically: cooling, salting, air-drying, fermenting and aging. Samples were collected at 0 d, 10 d, 20 d, 30 d, 65 d, 105 d and 165 d of processing. The results showed that the pH value remained stable in the range of 6.2~6.6. The moisture and water activity significantly decreased (p < 0.05) during processing. The chloride content, ash, total volatile basic nitrogen (TVB-N) and peroxide value (POV) significantly increased (p < 0.05), from 0.45% to 12.39%, from 3% to 17%, from 1.43 mg/kg to 8.98 mg/kg and from 1.39 g/100 g to 5.26 g/100 g, respectively. The thiobarbituric acid (TBARS) value reached its highest value of 0.39 mg MDA/kg at the end of the salting stage and then decreased to 0.34 mg MDA/kg. Eighteen free amino acids and fifteen free fatty acids were detected, and their contents were significantly increased during processing (p < 0.05). Volatile compounds were analyzed using solid-phase microextraction (SPME) and gas chromatography−mass spectrometry (GC−MS). Among 114 volatile compounds detected in dry-cured donkey leg, aldehydes, esters, alkane and alcohols were more abundant in the final products, with relative concentrations of 41.88%, 5.72%, 5.35% and 5.25%, respectively. Processing significantly affected the physical−chemical properties, which could contribute to the formation of flavor substances of dry-cured donkey leg.

Evaluation of the adsorption capacity and mechanism of soy protein isolate for volatile flavor compounds: Role of different oxygen-containing functional groups

Mechanism of soy protein isolate (SPI) adsorbing isomers of volatile flavor compounds (VFCs: 2-octanone, 1-octen-3-ol and octanal) were investigated by exploring the interaction between different oxygen-containing functional groups (OCF groups: carbonyl, alcohol hydroxyl and aldehyde group) and SPI in this study. VFCs made SPI aggregate into larger particle size, and an increase in β-sheet and β-turn was observed. Octanal has strongest binding capacity to SPI, followed by 1-octen-3-ol and 2-octanone. Fluorescence analysis revealed that static quenching occurred between the VFCs and SPI, which suggested that SPI-VFCs complex were formed. Double logarithmic Stern-Volmer indicated the strongest interaction between aldehyde group and SPI, which was proved by surface plasmon resonance. Finally, molecular docking results showed more hydrogen bonds between octanal and SPI. The results showed that aldehyde groups were more likely to interact with SPI than others, probably due to their tendency to form more hydrogen bonds.

UPLC-MS-MS-based lipidomics for the evaluation of changes in lipids during dry-cured mutton ham processing

Six key stages in the processing of dry-cured muton ham were selected, and changes in the main lipid metabolites as well as the major pathways involved were identified using a lipidic metabolomics approach based on UPLC-MS-MS. In total, 581 lipid metabolites from 22 subclasses were identified, including 521 significantly differential lipids (p < 0.05, VIP > 1). Glycerolipids (GL) were the most abundant lipids, followed by glycerophospholipids (GP), fatty acyls (FA), and sphingolipids (SL). PCA and OPLS-DA of metabolites showed that the quality of mutton ham changed the most during the P3 fermenting stage, including TG(18:1/18:2/18:3), PE(20:5/18:1), and TG(16:1/18:1/18:4) that were significantly downregulated, and CE(20:3), FFA(24:6), LPC(20:3/0:0), and FFA(18:4) that were significantly upregulated. Moreover, glycerophospholipid metabolism and sphingolipid metabolism were the key metabolic pathways involved in the processing of dry-cured mutton ham. Our results provide a basis for quality control and product improvement of dry-cured mutton ham.

Influence of Proteolysis on the Binding Capacity of Flavor Compounds to Myofibrillar Proteins

Proteolysis occurs extensively during postmortem aging, enzymatic tenderization and fermentation of meat products, whereas less is understood regarding how proteolysis affects meat flavor. Myofibrillar proteins (MP) were extracted from beef longissimus dorsi muscle and subsequently treated with three commercial proteases. The effect of proteolysis on the interactions between the treated MP and butyraldehyde, 2-pentanone, octanal and 2-octanone was investigated. The progress of proteolysis increased the degree of hydrolysis (DH) and the surface hydrophobicity but decreased the turbidity and particle size. Fluorescence-quenching analysis results indicated that the enzymatic treatment generally increased the quenching constant (Ksv) between the treated MP and ketones but decreased the Ksv between the treated MP and aldehydes, and the papain treatment changed the Ksv value to a larger degree than treatment with proteinase K and bromelain. The adsorption assay showed that the proteinase K treatment largely increased the adsorption capacity of the MP to octanal (by 15.8−19.3%), whereas the bromelain treatment significantly reduced the adsorption capacity of the treated MP to butyraldehyde (by 6.0−7.9%) and 2-pentanone (by 9.7−11.9%). A correlation analysis demonstrated a strong positive correlation (0.859, p < 0.05) between the DH of the MP and the adsorption ability of the treated MP to octanal. This study highlighted the significant but complex influence of proteolysis on MP binding capacity to flavor compounds.

The Effect of Catabolic Transformations of Proteins and Fats on the Quality and Nutritional Value of Raw Ripened Products from Zlotnicka Spotted and Zlotnicka White Meat

The aim of the study was to compare the advancement of the ripening as well as catabolic changes in proteins and fats of Zlotnicka Spotted (ZS) and Zlotnicka White (ZW) meat and their impact on the quality and nutritional value of ready-to-eat products. The meat of the breeds ZS and ZW differed not only in the basic chemical composition but also in the susceptibility to catabolic transformations of proteins and lipids, which translated into a separate technological and nutritional quality as well as the profile of volatile odor compounds. Loins due to their compact histological structure, low pH (5.4) and decreased water activity (0.92–0.93) were characterized by a lower number of coagulase-negative cocci (3.3 log cfu/g) compared to hams. The products of both breeds differed in the content of selected neutral glucogenic amino acids with a pI in the range of 5.6–6.1 mainly. The content of biogenic amines was therefore completely dependent on the metabolic potential of acidifying bacteria. Larger number of lactic acid bacilli (7.5–7.7 log cfu/g) and lactic acid cocci (7.9–8.3 log cfu/g), as well as a higher content of saturated (55.2–53.7%) and polyunsaturated fatty acids (6.4–7.0%) shaped the final pH of hams (5.3). Presence of aldehydes, ketones and alcohols indicated existing fat oxidation despite the small values of the TBA index of hams (1.1 mg/kg) and loins (0.4–0.6 mg/kg). The volatile compounds that differentiated products of ZS and ZW formed by the oxidation and microbial activity, were, primarily: octanal, 1-hydroxypropan- 2-one, 3-methylpentan-2-one, propane-1,2-diol, 2,5-dimethylfuran and 3-hydroxybutan- 2-one, butane-2,3-dione, butane-1,2-diol, respectively.

Effect of deacetylated konjac glucomannan on heat-induced structural changes and flavor binding ability of fish myosin

This work investigated the effects of deacetylated konjac glucomannan (DKGM) on heat-induced structural changes and flavor binding in bighead carp myosin. DKGM could cross-link with fish myosin to form a thermostable complex and improve the gel strength of myosin. The incorporation of DKGM increased the surface hydrophobicity and total sulfhydryl content of heat-induced myosin. Increasing DKGM concentrations resulted in a decrease in the absolute zeta potential and a continuous increase in particle size. DKGM addition significantly reduced the α-helical content of myosin with a concomitant increase in β-sheet, β-turn, and random coil content. The binding abilities of myosin to flavors were significantly enhanced by increasing amounts of DKGM, attributing to the accelerative unfolding of myosin secondary structures and the exposure of additional hydrophobic and thiol binding sites. Increased numbers of available hydroxyl groups after DKGM treatment could also cause an increase of flavor adsorption by hydrogen bonding.

Capacity of myofibrillar protein to adsorb characteristic fishy-odor compounds: Effects of concentration, temperature, ionic strength, pH and yeast glucan addition

The capacity of myofibrillar protein (MP) to adsorb fishy-odors (hexanal, nonanal, 1-octen-3-ol) was investigated under the influences of concentration, temperature, pH, ionic strength and yeast glucan (YG) addition. The adsorption of MP for fishy-odors was in the order of nonanal > hexanal > 1-octen-3-ol. With increasing MP concentration, the binding of protein-aldehydes was facilitated, in contrast to a decrease trend in binding to 1-octen-3-ol. Meanwhile, MP adsorption capacity for off-odors peaked at 40 °C. Additionally, low ionic strength (0.2 mol/L) could promote MP adsorption for off-odors, while high ionic strength (0.6-1.0 mol/L) could reduce its adsorption for hexanal and 1-octen-3-ol. Moreover, MP had higher adsorption capacity under extreme pH values (pH 3 and 11). Furthermore, YG was shown as an ideal additive to adsorb off-odors due to its large specific surface area and good stability. This work provides useful information on how to deodorize fishy-odors in fish products.

Effect of heat treatment duration on the interaction between fish myosin and selected flavor compounds

BACKGROUND

Interactions between flavor compounds and proteins during food processing are critical to flavor perception of the final product. Here, we investigated the effect of the duration of heat treatment on the interaction between bighead carp myosin and selected flavor compounds including hexanal, heptanal, octanal, nonanal, (E)-2-heptenal, and 1-octen-3-ol.

RESULTS

The binding of flavor compounds to native myosin was strong and decreased in the order nonanal > octanal > (E)-2-heptenal > heptanal > hexanal >1-octen-3-ol. The aldehydes, especially trans-2-undecenal, were more conducive to hydrophobic binding to myosin than alcohols. Within the initial 5 min of heating, the surface hydrophobicity and total sulfhydryl exposure increased, while α-helix turned into β-sheets, β-turns, and random coils. However, upon further heating, the hydrophobicity and sulfhydryl contents declined, β-sheets, β-turns and random coils shifted to α-helix. Throughout the heating process, the particle size increased, and the absolute zeta potential decreased continuously, indicating that thermal aggregation of myosin occurred simultaneously. Changes in binding capacities of flavor compounds to myosin were consistent with changes in hydrophobicity and sulfhydryl contents.

CONCLUSION

The initial enhancement of the flavor-binding capacity of myosin was attributed to the unfolding of secondary structures by exposing more hydrophobic bonding sites and hydrogen bonding sites. The rebuilding and aggregating of myosin was enhanced upon prolonged heating, thus favoring hydrophobic protein-protein interactions and weakening the resultant flavor binding capacity of myosin.

Influence of proteolytic enzyme treatment on the changes in volatile compounds and odors of beef longissimus dorsi

Enzymatic tenderization is extensively applied in the meat industry, whereas its influence on meat flavor has seldom been evaluated. Proteinase K, papain, bromelain and Flavourzyme® were used to treat beef muscle, and the changes in volatile compounds and odors were subsequently analyzed. Proteolysis by proteinase K was found to elevate the average bitterness of the identified peptides by generating peptides with high Q values, whereas proteolysis by papain generated the highest level of amino acids. Enzymatic treatment by Flavourzyme and bromelain significantly elevated the levels of ketones and odors, whereas excessive proteolysis by papain and proteinase K largely reduced the levels of esters and aldehydes. The level of amino acids and degree of hydrolysis were found to be predominant factors that regulated the level of volatiles and odors. These results highlighted the huge influence of enzymatic tenderization on meat flavor, depending on degree of hydrolysis and cleavage pattern of applied proteases.

The binding of key fishy off-flavor compounds to silver carp proteins: a thermodynamic analysis

The binding of key fishy off-flavor compounds (KFOCs), heptanal, octanal, nonanal, and 1-octen-3-ol, to silver carp proteins (total myofibrillar protein, myosin, and actin) was studied. Myosin was the primary binding receptor for all four KFOCs, and it showed the strongest binding at neutral pH and at higher ionic strengths. Thermodynamic models were applied to evaluate the number of binding sites, the binding constant, and the Gibbs free energy for the binding of the KFOCs to myosin. Myosin had approximately 1.0 sites for binding with the three linear-chain aldehydes and about 1.6 sites for binding with 1-octen-3-ol. Moreover, myosin showed the highest affinity for 1-octen-3-ol, and both its binding constant and its number of binding sites with the three linear-chain aldehydes were negatively correlated with the chain length. For all four KFOCs, the trends of the Gibbs free energies were the opposite of those observed for the binding constant and the number of binding sites. These results may provide a theoretical basis for improving the deodorization efficiency of traditional surimi rinsing methods by adjusting the properties of the solutions used.

Myosin was shown to be the primary binding receptor of the four KFOCs and showed the strongest binding under neutral pH and high ionic strength. Its affinity for 1-octen-3-ol was the highest.

Effect of heat treatment on the binding of selected flavor compounds to myofibrillar proteins

BACKGROUND

The influence of heat-induced structural modifications of grass carp myofibrillar protein (MP) on its ability to bind to selected aldehydes (hexanal, heptanal, octanal and nonanal) was investigated. The interactions of MP and flavor compounds were investigated using HS-GC-MS, intrinsic fluorescence spectra, Raman spectra, SDS-PAGE, turbidity, total sulfhydryl content and surface hydrophobicity.

RESULTS

The ability to bind to aldehydes was strongly influenced by changes in the structure and surface of proteins during the heating process (0-30 min). During the first 0-10 min of heating, the flavor-binding ability increased, which is likely attributable to increased surface hydrophobicity and total sulfhydryl content, and to the unfolding of secondary structures of MP by exposure to reactive amino acids, sulfhydryl groups and hydrophobic bonding sites. Nevertheless, lengthy heating (>10 min) caused protein refolding and accelerated aggregation of protein, thus reducing hydrophobic interactions and weakening the resultant capacity of MP to bind to flavor compounds.

CONCLUSION

The results suggested that hydrophobic interactions were enhanced upon short-term heating, whereas long-term heating weakend them. The results provide information concerning improvement of the flavor profile of freshwater fish surimi products. © 2019 Society of Chemical Industry.

Understanding the implications of current health trends on the aroma of wet and dry cured meat products

Meat product aroma is affected by various meat processing factors. In this review the main biochemical reactions involved in the development of meat product aroma (wet, dry cured and fermented) are fully described. Moreover, the different techniques used for key aroma elucidation in meat products are defined. The aroma compounds present in wet, dry cured and fermented meat products (sausage and whole piece) have been summarized. The mechanisms of aroma formation during the manufacture of cooked and dry/fermented meat products are described. In wet meat products the main reactions described are lipid degradation (oxidative reactions), Maillard reactions, Strecker degradation, and thiamine degradation while in dry meat products are; lipid degradation (oxidative reactions), thiamine degradation, microbial carbohydrate fermentation and microbial metabolism including complex interactions among them such as the amino acid degradation produced by lipid oxidation products. Finally, the effect of current health trends such as salt, fat and nitrifying content reduction on the development of meat product aroma is explained.

Peptide Modified ZnO Nanoparticles as Gas Sensors Array for Volatile Organic Compounds (VOCs)

In this work a peptide based gas sensor array based of ZnO nanoparticles (ZnONPs) has been realized. Four different pentapeptides molecularly modeled for alcohols and esters having cysteine as a common spacer have been immobilized onto ZnONPs. ZnONPs have been morphologically and spectroscopically characterized. Modified nanoparticles have been then deposited onto quartz crystal microbalances (QCMs) and used as gas sensors with nitrogen as carrier gas. Analysis of the pure compounds modeled demonstrated a nice fitting of modeling with real data. The peptide based ZnONPs had very low sensitivity to water, compared to previously studied AuNPs peptide based gas sensors allowing the use of the array on samples with high water content. Real samples of fruit juices have been assayed; stability of the signal, good repeatability, and discrimination ability of the array was achieved.