Search Results (28)

The aim of this study was to evaluate differences in the physicochemical characteristics, fatty acid profiles and volatile compounds of different muscle types (semimembranosus (SM), biceps femoris (BF) and semitendinosus (ST)) used to produce dry-cured Bísaro ham. Sixteen dry-cured hams were used. The physicochemical parameters were significantly affected by the muscle type, with the differences being mainly related to the different drying degrees and the intramuscular fat and collagen contents of the fresh muscles. Additionally, the type of muscle had a significant influence on the polyunsaturated fatty acids, such that the muscle with the highest fat content (ST) had the lowest PUFA content and vice versa. There were strong significant differences in the total content of volatile compounds derived from the Strecker reaction, which was higher in the ST muscle, and in the proportions of these compounds with different functional groups. The amount of sulfur compounds was also affected by the muscle type and was higher in the SM muscle. Due to the great impact of Strecker-derived and sulfur compounds on the flavor of the cured hams, these differences would affect the flavor perception of the different muscles. The variability between muscles in composition, fatty acids and volatile compounds allowed for discrimination of the samples by muscle type using multivariate analysis. Full article

Short- and medium-sized peptides have long been used as effective and versatile organocatalysts. In the early 80s, Inoue used diketopiperazines in the Strecker reaction, while Juliá and Colonna reported the epoxidation of chalcone catalyzed by poly-L-Ala. Since then, a variety of peptide-catalyzed reactions have been described. However, peptide synthesis typically implicates the use of toxic reagents and generates wastes; therefore, peptide recycling is expected to significantly improve the overall sustainability of the process. Easy recovery and recycling of peptide catalysts can be expediently attained by covalent binding, inclusion, or adsorption. In addition, immobilization can significantly accelerate the screening of new peptide catalysts. For these reasons, diverse supports have been tested, including natural or synthetic polymers, porous polymeric networks, inorganic porous materials, organic-inorganic hybrid materials, and finally metal–organic frame-works. Full article

This study investigated the effects of dietary Antarctic krill meal (AKM) on the physiological metabolism and flavor quality of adult Eriocheir sinensis ovaries during the postharvest temporary rearing. The AKM concentrations tested were 0% (including negative control group and positive control group), 2%, 4%, 6%, and 8%. The results indicate that the E. sinensis ovaries in 8% AKM group produced the highest levels of aroma compounds after thermal processing, including hexanal, heptanal, phenylacetaldehyde, 3-octanone, and 2-methylbutanoic acid ethyl ester. The 8% AKM and negative control group were analyzed by UPLC-MS/MS combined with the nontargeted and widely targeted metabolomics technique. The AKM altered the composition of aroma precursors by adjusting the metabolism of glycerophospholipid, linoleic acid, α-linolenic acid, and amino acid in ovaries. Moreover, lipids composed of polyunsaturated fatty acids (PUFAs) were significantly upregulated (p < 0.05). Dietary supplementation with 8% AKM had the best effect on improving the ovarian flavor quality of E. sinensis. During the postharvest temporary rearing, more aromatic precursors were produced by regulating physiological metabolism. The ovarian flavor was enhanced by lipid oxidation, Maillard reaction, and Strecker degradation during thermal processing. Full article

This review highlights the most recent applications of Cd(II)-carboxylate-based coordination polymers (Cd(II)-CBCPs), such as sensors, catalysts, and storage materials, in comparison with those of Zn(II) counterparts. A wide range of species with luminescence properties were designed by using proper organic fluorophores, especially a carboxylate bridging ligand combined with an ancillary N-donor species, both with a rigid structure. These characteristics, combined with the arrangement in Cd(II)-CBCPs’ structure and the intermolecular interaction, enable the sensing behavior of a plethora of various inorganic and organic pollutants. In addition, the Lewis acid behavior of Cd(II) was investigated either in developing valuable heterogeneous catalysts in acetalization, cyanosilylation, Henry or Strecker reactions, Knoevenagel condensation, or dyes or drug elimination from wastewater through photocatalysis. Furthermore, the pores structure of such derivatives induced the ability of some species to store gases or toxic dyes. Applications such as in herbicides, antibacterials, and electronic devices are also described together with their ability to generate nano-CdO species. Full article

Tracking coffee roasting at an industrial scale for quality control is challenging. Bean color is a practical gauge for monitoring and regulating the process but only occurs before and after the process. This study highlights the feasibility of monitoring the process throughout using Raman spectroscopy. Strecker degradation and the Maillard reaction contribute to various aromatic compounds that can serve as markers in quality monitoring. Among these are chlorogenic acids (CGAs), recognized as pivotal factors determining the desired aroma. Here, drum and fluidized bed roaster processes were monitored, capitalizing on the chemical alterations induced by high temperatures (140–200 °C), particularly through the Maillard reaction. These chemical changes manifest in the scattered light signal. For real-time monitoring, Raman spectra were taken every 10 ms in selected ranges, with an average calculated every second. Utilizing a calibration matrix from a High-Pressure Liquid Chromatography (HPLC) method, CGA concentration becomes the control variable for assessing roasting progress. This study reveals the potential of Raman spectroscopy for tracking CGA during roasting. It establishes a correlation between inelastic scattered light and CGA validated through laboratory measurements and fixed roasting conditions, resulting in a theoretical CGA concentration that can be used as a process termination criterion. Full article

The objective of this study is to determine the effect of two distinct cooking techniques, namely roasting and stewing, on the formation of volatile compounds in various beef muscles (Semimembranosus, Biceps femoris, and Rectus femoris) and how this relates to consumer acceptance. The research employs the concept of volatile “marker” compounds to discern the influence of cooking techniques on the flavor profile of beef. Eighteen “marker compounds” were selected to represent a number of the mechanisms of formation and quantified in beef subjected to two different cooking methods. While no statistically significant differences were observed in consumer evaluations between the two cooking methods, notable disparities emerged in the consumer assessments of specific muscle cuts. Notably, the Rectus femoris muscle received the highest ratings (p < 0.05) among other evaluated muscles. The utilization of Solid-Phase Microextraction (SPME) and gas chromatography–mass spectrometry (GC-MS) methods for the analysis of volatile “marker compounds” in beef proved effective in highlighting significant differences in flavor compound classes between cooking methods, and these differed between muscles. The main effect was of the cooking method with stewed beef aroma having approximately 39× more dimethyl trisulphide, 9× more dimethyl disulphide, 7× more pentanal, 3× more hexanal, and twice as much benzaldehyde and 2-methylthiophene. Dimethyldisulphide, dimethyltrisulphide, hexanal, and heptanal, therefore, emerged as characteristic volatile compounds associated with the stewing cooking technique, suggesting their potential as markers for lipid and other oxidation reactions. This work indicates that certain lipid oxidation compounds, Strecker aldehydes, and sulfur compounds can be markers for the undesirable and/or desirable flavors of cooked beef, but that this depends on the cooking method chosen. It shows that flavor differences may be understood through the analysis of volatile flavor compounds in association with palatability and other chemical measurements. Full article

Natural chiral amino acids typically adopt an L structural configuration. While a preference for specific molecular chiralities is observed throughout biology and cellular chemistry, the origins of this preference are unclear. In a previous report the origin of enantiomeric selectivity was analyzed in terms of an “RNA World” model, and a pathway to a chiral preference for d-ribose was proposed based on the autocatalytic transformation of glyceraldehyde as a precursor to the formation of sugars. Metal-ion-promoted catalysis allows the parity non-conserving (PNC) weak nuclear interaction to influence the chirality of a nascent chiral carbon center. Since the PNC effect is the only natural property with an inherent handedness, it is an obvious candidate to influence enantiomeric preference from a catalytic reaction performed over geologically relevant time scales. The PNC influence requires and emphasizes the important role of catalytic metal ions in primordial chemistry. In this study, the impact of geologically available divalent calcium and higher Z alkaline earth elements are examined as mediators of chiral preference. Detailed calculations of the magnitude of the effect are presented, including the influence of time, temperature, pH, and metal ion identity. It is concluded that metal ions can direct chiral preference for amino acid synthesis via a metal-promoted autocatalytic Strecker reaction within a relatively short geological timeframe, thereby providing a pool of l-amino acids for catalytic chemistry evolving either from an RNA-world model of molecular evolution or alternative pathways to protein synthesis. Full article

Excessive consumption of simple sugars is responsible for non-communicable diseases such as obesity, cardiovascular diseases, and diabetes. Xylitol has anticarcinogenic, prebiotic-like characteristics and a lower glycaemic index and caloric value than sugars, which makes it a valuable alternative sweetener. The aim of this study was to examine the effects of storage of volatile compounds and sensory profiles of cookies containing xylitol as a sucrose alternative or sucrose by applying solid-phase microextraction gas chromatography/mass spectrometry and quantitative descriptive analysis. The volatile compound profiles of both kinds of cookies were similar, especially regarding markers of Maillard reactions (Strecker aldehydes, pyrazines) and unfavourable compounds (aldehydes, hydrocarbons, and organic acids). Throughout the period of storage lasting 0–9 months, the total content of hydrocarbons was stable and averaged 10.2% in xylitol cookies and 12.8% in sucrose cookies; their storage for 12 months significantly (p < 0.05) increased the contents to 58.2% and 60.35%, respectively. Unlike sucrose, xylitol improved the stability of the pH and water activity of cookies and sensory attributes such as buttery aroma and texture characteristics during 12 months of storage. The results indicated that 9 months of cookie storage was the maximum recommended period. The inclusion of xylitol in cookies might replace sucrose and high-fructose-corn syrup and synthetic additives commonly used in industrial production. Full article

The deepening of color of ready-to-eat (RTE) abalone during storage leads to sensory quality degradation, which seriously affects the shelf life of products and consumers’ purchasing desire. The goal of this study is to look into the causes of non-enzymatic browning and lipid oxidation, as well as how to control them, and their effect on the color of RTE abalone during storage. The control, bloodletting and antioxidants groups (lactic acid, citric acid and 4-hexylresorcinol) of RTE abalone were stored for 0, 20 and 40 days at 40 °C, respectively, to explore the rule and mechanism of the color change in RTE abalone. This research shows that RTE abalone undergoes browning during storage. Meanwhile, the content of reducing sugar, phenols and unsaturated fatty acids decreases, while the formation of lipid hydroperoxides and aldehydes increases during storage. In addition, the color change in RTE abalone during storage is mainly related to the Maillard reaction, while the lipid oxidation mainly forms pyrrole and participates in the Strecker degradation process as part of the Maillard reaction. The quality of RTE abalone can be maintained by controlling browning effectively as well as lipid oxidation through bloodletting and the addition of antioxidants to ensure that RTE abalone has high storage stability. According to our research, bloodletting and the addition of antioxidants to RTE abalone have a good application prospect and popularizing value in the storage of RTE abalone. Full article

The white pulp of the Chinese water chestnut (CWC) is crisp and sweet with delicious flavours and is an important ingredient in many Chinese dishes. Phenylacetaldehyde is a characteristic flavoured substance produced in the steaming and cooking process of CWC. The steaming process and conditions were simulated to construct three Maillard reaction systems which consisted of glucose and phenylalanine, and of both alone. The simulation results showed that glucose and phenylalanine were the reaction substrates for the formation of phenylacetaldehyde. The intermediate α-dicarbonyl compounds (α-DCs) and the final products of the simulated system were detected by solid-phase microextraction (SPME) and gas chromatography–mass spectrometry (GC-MS) methods. Through the above methods the formation mechanism of phenylacetaldehyde is clarified; under the conditions of the steaming process, glucose is caramelized to produce Methylglyoxal (MGO), 2,3-Butanedione (BD), Glyoxal (GO) and other α-DCs. α-DCs and phenylalanine undergo a Strecker degradation reaction to generate phenylacetaldehyde. The optimal ratio of the amount of substance of glucose to phenylalanine for Maillard reaction is 1:4. The results can provide scientific reference for the regulation of flavour substances and the evaluation of flavour quality in the steaming process of fruits and vegetables. Full article

In this work, two new 1D Cd(II) coordination polymers (CPs), [Cd(L1)(NMF)₂]_n (1) and [Cd(L2)(DMF)(H₂O)₂]_n·n(H₂O) (2), have been synthesized, characterized and employed as catalysts for the microwave-assisted solvent-free Strecker-type cyanation of different acetals. Solvothermal reaction between the pro-ligand, 5-{(pyren-1-ylmethyl)amino}isophthalic acid (H₂L1) or 5-{(anthracen-9-ylmethyl)amino}isophthalic acid (H₂L2), and Cd(NO₃)₂.6H₂O in the presence of NMF or DMF:THF solvent, produces the coordination polymer 1 or 2, respectively. These frameworks were characterized by single-crystal and powder X-ray diffraction analyses, ATR-FTIR, elemental and thermogravimetry analysis. Their structural analysis revealed that both CPs show one-dimensional structures, but CP 1 has a 1D double chain type structure whereas CP 2 is a simple one-dimensional network. In CP 1, the dinuclear {Cd₂(COO)₄} unit acts as a secondary building unit (SBU) and the assembly of dinuclear SBUs with deprotonated ligand (L1²⁻) led to the formation of a 1D double chain framework. In contrast, no SBU was observed in CP 2. To test the catalytic effectiveness of these 1D compounds, the solvent-free Strecker-type cyanation reactions of different acetals in presence of trimethylsilyl cyanide (TMSCN) was studied with CPs 1 and 2 as heterogenous catalysts. CP 1 displays a higher activity (yield 95%) compared to CP 2 (yield 84%) after the same reaction time. This is accounted for by the strong hydrogen bonding packing network in CP 2 that hampers the accessibility of the metal centers, and the presence of the dinuclear Cd(II) SBU in CP 1 which can promote the catalytic process in comparison with the mononuclear Cd(II) center in CP 2. Moreover, the recyclability and heterogeneity of both CPs were tested, demonstrating that they can be recyclable for at least for four cycles without losing their structural integrity and catalytic activity. Full article

Meat is a rich source of different volatile compounds. The final flavor of meat products depends on the raw material and processing parameters. Changes that occur in meat include pyrolysis of peptides and amino acids, degradation of sugar and ribonucleotides, Maillard’s and Strecker’s reactions, lipid oxidation, degradation of thiamine and fats, as well as microbial metabolism. A review of the volatile compounds’ formation was carried out and divided into non-thermal and thermal processes. Modern and advanced solutions such as ultrasounds, pulsed electric field, cold plasma, ozone use, etc., were described. The article also concerns the important issue of determining Volatile Organic Compounds (VOCs) markers generated during heat treatment. Full article

Chiral primary α-amino amides, consisting of an adjacent enamine bonding site (Bronsted base site), a hydrogen bonding site (Bronsted acid site), and flexible bulky substituent groups to modify the steric factor, are proving to be extremely valuable bifunctional organocatalysts for a wide range of asymmetric organic transformations. Primary α-amino amides are less expensive alternatives to other primary amino organocatalysts, such as chiral diamines and cinchona-alkaloid-derived primary amines, as they are easy to synthesize, air-stable, and allow for the incorporation of a variety of functional groups. In recent years, we have demonstrated the catalytic use of simple primary α-amino amides and their derivatives as organocatalysts for the aldol reaction, Strecker reaction, Michael tandem reaction, allylation of aldehydes, reduction of N-Aryl mines, opening of epoxides, hydrosilylation, asymmetric hydrogen transfer, and N-specific nitrosobenzene reaction with aldehydes. Full article

Chitosan–genipin (Ch-Ge) films have been proposed for the replacement of sulfur dioxide (SO₂) in white wines preservation to circumvent the adverse health consequences caused by SO₂ intake. To assess the effects of different-sized Ch-Ge films (25 and 100 cm²) on wine composition compared to SO₂-treated and untreated wines, nuclear magnetic resonance metabolomics was applied. Relative to SO₂, 100 cm² films induced significant changes in the levels of organic acids, sugars, amino acids, 5-hydroxymethylfurfural, among other compounds, while 25 cm² films appeared to induce only small variations. The observed metabolite variations were proposed to arise from the mitigation of fermentative processes, electrostatic interactions between acids and the positively charged films and the promotion of Maillard and Strecker reactions. Qualitative sensory analysis showed that wines maintained overall appropriate sensory characteristics, with 100 cm² film treated wines showing slightly higher attributes. Based on these results, the possibility of using Ch-Ge films as a replacement for SO₂ treatment is discussed. Full article

The volatile composition and odor of meat and meat products is based on the precursors present in the raw meat. These are influenced by various pre-slaughter factors (species, breed, sex, age, feed, muscle type). Furthermore, post-mortem conditions (chiller aging, cooking conditions, curing, fermentation, etc.) determine the development of meat volatile organic compounds (VOCs). In this review, the main reactions leading to the development of meat VOCs such as the Maillard reaction; Strecker degradation; lipid oxidation; and thiamine, carbohydrate, and nucleotide degradation are described. The important pre-slaughter factors and post-mortem conditions influencing meat VOCs are discussed. Finally, the pros, cons, and future perspectives of the most commonly used sample preparation techniques (solid-phase microextraction, stir bar sorptive extraction, dynamic headspace extraction) and analytical methods (gas chromatography mass spectrometry and olfactometry, as well as electronic noses) for the analysis of meat VOCs are discussed, and the continued importance of sensorial analysis is pinpointed. Full article