Elucidating the combined effect of sample preparation and solid-phase microextraction conditions on the volatile composition of cooked meat analyzed by capillary gas chromatography coupled with mass spectrometry

Revealing the characteristic aroma and boundary compositions of five pig breeds based on HS-SPME/GC-O-MS, aroma recombination and omission experiments

To clarify the characteristic aroma compounds and flavor discrepancies of five Chinese typical pig species, headspace-solid phase microextraction gas chromatography-olfactometry-mass spectrometry (HS-SPME/GC-O-MS), electronic nose (E-nose), aroma recombination and omission experiments were used to analyze the characteristic aroma and boundary of five boiled pork. A total of 38 volatile compounds were identified, of which 14 were identified as important odorants with odor-activity values (OAVs) greater than 1. Aroma recombination and omission experiments revealed 8 key characteristic aroma compounds, which significantly contributed to the overall aroma. Sensory evaluation of the recombination model with the 8 aroma compounds scored 3.0 to 4.0 out of 5 points. 12 potential markers were identified to distinguish by principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA), including (E)-2-octenal, 3-ethyl-2-methyl-1,3-hexadiene, (E)-2-heptenal, 2-pentylfuran, cyclooctanol, 1-heptanol, sec-butylamine, D-limonene, N-vinylformamide, 2,3-octanedione, 2-ethylfuran and 3-pentanamine. Alongside benzaldehyde and pentanal, the combinations and fluctuations of these 14 aroma markers were proposed to constitute the aroma boundaries of different pork breeds. The aroma-active substances were able to effectively differentiate different breeds.

Selection and quantification of volatile indicators for quality deterioration of reheated pork based on simultaneously extracting volatiles and reheating precooked pork

This study was to screen and quantify characteristic volatiles tied to the quality deterioration of reheated pork via simultaneously reheating (75 °C, 30 min) and collecting headspace volatiles of precooked pork (100 °C, 10 min; stored: 0 °C, 0-14 d) for GC-MS analysis. The concentrations of hexanal (6.05 ± 0.86-12.05 ± 0.44 mg/kg), (E)-2-octenal (1.54 ± 0.16-3.07 ± 0.08 mg/kg), (E,E)-2,4-heptadienal (1.52 ± 0.44-2.58 ± 0.31 mg/kg) and 8 other selected volatiles in reheated pork increased as the storage time of the precooked counterparts increased. The increase rate of hexanal was 2.9-199 times faster than that of other volatiles based on zero-order reaction fitting (R² = 0.876-0.997). Results from clustering analysis of these volatiles were consistent with their formation pathways tied to lipid autooxidation. This simple approach, reheating and collecting volatiles of precooked meat concurrently, introduces a new possibility for standardizing volatile analysis of precooked meats required being reheated before consumption.

Rapid analysis of meat floss origin using a supervised machine learning-based electronic nose towards food authentication

Authentication of meat floss origin has been highly critical for its consumers due to existing potential risks of having allergic diseases or religion perspective related to pork-containing foods. Herein, we developed and assessed a compact portable electronic nose (e-nose) comprising gas sensor array and supervised machine learning with a window time slicing method to sniff and to classify different meat floss products. We evaluated four different supervised learning methods for data classification (i.e., linear discriminant analysis (LDA), quadratic discriminant analysis (QDA), k-nearest neighbors (k-NN), and random forest (RF)). Among them, an LDA model equipped with five-window-extracted feature yielded the highest accuracy values of >99% for both validation and testing data in discriminating beef, chicken, and pork flosses. The obtained e-nose results were correlated and confirmed with the spectral data from Fourier-transform infrared (FTIR) spectroscopy and gas chromatography-mass spectrometry (GC-MS) measurements. We found that beef and chicken had similar compound groups (i.e., hydrocarbons and alcohol). Meanwhile, aldehyde compounds (e.g., dodecanal and 9-octadecanal) were found to be dominant in pork products. Based on its performance evaluation, the developed e-nose system shows promising results in food authenticity testing, which paves the way for ubiquitously detecting deception and food fraud attempts.

Flavor formation based on lipid in meat and meat products: A review

Meat product is popular throughout the world due to its unique taste. Flavor is one of the most important quality characteristics of meat products and also is a key influencing factor in the overall acceptability of meat products. The flavor of meat products is formed by precursors undergoing a series of complex reactions. During meat product processing, lipids are hydrolyzed by lipase to produce flavor precursors such as free fatty acid, then further oxidized to form volatile flavor compounds. This review summarizes lipolysis, lipid oxidation, and interaction of lipid with Maillard reaction and amino acid during meat products processing and storage as well as influencing factors on lipid degradation including raw meat (source of meat, feeding pattern, and castration), processing methods (thermal processing, nonthermal processing, salting, and fermentation) and additives. Meanwhile, the volatile compounds produced by lipids in meat products including aldehydes, alcohols, ketones, and hydrocarbons are summed up. Analytical methods of volatile compounds and the application of lipidomics analysis in mechanisms of flavor formation of meat products are also reviewed. PRACTICAL APPLICATIONS: Flavor is one of the most important quality characteristics of meat products, which influences the acceptability of meat products for consumption. Lipids play an important role in the flavor formation of meat products. Understanding the relationship between flavor compounds and changes in lipid compositions during the processing and storage of meat products will be helpful to control the quality of meat products.

Quality changes of duck meat during thermal sterilization processing caused by microwave, stepwise retort, and general retort heating

The quality changes of duck meat during thermal sterilization using microwave, stepwise retort and general retort heating were evaluated. Results showed that compared with stepwise retort and general retort, duck meat subjected to microwave showed significantly higher gumminess, chewiness, cohesiveness and resilience as well as glutamic acid, lysine and total amino acids. Low-field NMR revealed that the relative content of immobilized water after microwave and stepwise retort treatment was significantly higher than that after general retort treatment. The relative content of 1-octen-3-ol with characteristic mushroom aroma was significantly higher with microwave and stepwise retort heating than with general retort heating, while 2-pentyl-furan with poor taste was only detected with general retort heating. The muscle bundles subjected to microwave were neatly arranged, similar to those with no thermal sterilization. Overall, the meat quality after three thermal sterilization treatment was microwave > stepwise retort > general retort.

Characterisation of the volatile profile of microalgae and cyanobacteria using solid-phase microextraction followed by gas chromatography coupled to mass spectrometry

Microalgae and microalgae-derived ingredients are one of the top trends in the food industry. However, consumers’ acceptance and purchase intention of a product will be largely affected by odour and flavour. Surprisingly, the scientific literature present a very limited number of studies on the volatile composition of microalgae and cyanobacteria. In order to fill the gap, the main objective of the present study was to elucidate the volatile composition of seven microalgal and cyanobacterial strains from marine and freshwaters, with interest for the food industry while establishing its potential impact in odour. Among the seven selected strains, Arthrospira platensis showed the highest abundance and chemical diversity of volatile organic compounds (VOCs). Aldehydes, ketones, and alcohols were the families with the highest diversity of individual compounds, except in Arthrospira platensis and Scenedesmus almeriensis that showed a profile dominated by branched hydrocarbons. Marine strains presented a higher abundance of sulfur compounds than freshwater strains, while the ketones individual profile seemed to be more related to the taxonomical domain. The results of this study indicate that the VOCs composition is mainly driven by the individual strain although some volatile profile characteristics could be influenced by both environmental and taxonomical factors.

Effect of ageing time on the volatile compounds from cooked horse meat

Volatile compounds from cooked and aged (0, 7, 14, 21 days) Hispano-Bretón horse meat (loin) were analyzed by solid-phase microextraction coupled to gas chromatography-mass spectrometry. A total of 77 volatile compounds were found, from which aldehydes were the predominant family. Most of the identified compounds had their origin in the degradation of lipids, with a negligible contribution of Maillard derived products. Odour impact ratios were calculated and used as indicators of the contribution of each compound to the total aroma and aldehydes were, in general, the major contributors to cooked horse meat aroma. Results revealed that ageing affected 15 of the volatile compounds detected. From them, hexadecanal and 2- and 3-methylbutanal significantly increased during ageing, presumably affecting the cooked meat odour as these have considerable odorant impact. Under the present study conditions, periods longer than 14 days would be necessary for significant changes in the volatile profile of cooked horse meat.

Analysis of Volatiles in Food Products

The evaluation of volatiles in food is an important aspect of food production. It gives knowledge about the quality of foods and their relationship to consumers’ choices. Alcohols, aldehydes, acids, esters, terpenes, pyrazines, and furans are the main chemical groups that are involved in aroma formation. They are products of food processing: thermal treatment, fermentation, storage, etc. Food aroma is a mixture of varied molecules. Because of this, the analysis of aroma composition can be challenging. The four main steps can be distinguished in the evaluation of the volatiles in the food matrix as follows: (1) isolation and concentration; (2) separation; (3) identification; and (4) sensory characterization. The most commonly used techniques to separate a fraction of volatiles from non-volatiles are solid-phase micro-(SPME) and stir bar sorptive extractions (SBSE). However, to study the active components of food aroma by gas chromatography with olfactometry detector (GC-O), solvent-assisted flavor evaporation (SAFE) is used. The volatiles are mostly separated on GC systems (GC or comprehensive two-dimensional GCxGC) with the support of mass spectrometry (MS, MS/MS, ToF–MS) for chemical compound identification. Besides omics techniques, the promising part could be a study of aroma using electronic nose. Therefore, the main assumptions of volatolomics are here described.