The effect of free fatty acids on the odour of pork investigated by sensory profiling and GC-O-MS

Flavoromics Analysis of Passion Fruit-Roasted Chicken

Currently, research on the flavor components and their dynamic changes in roasted chicken with a special flavor is rare. In this study, a passion fruit-roasted chicken was prepared, its characteristic flavor components were profiled by flavoromics, and their evolution patterns and precursors were determined. The results showed that the characteristic flavor component with the highest contribution rate was ethyl butyrate (50.44%). In particular, some unique flavor compounds were identified compared with other roasted chicken products available. The main volatile flavor components in all stages of processing were alcohols, esters, and hydrocarbons, 15 to 30 min of roasting is an important stage for establishing the aroma system, and at the end, hydrocarbons were the main volatile compounds. During the 30-day storage period, the characteristic flavor components included ethyl butyrate, ethyl maltol, β-caryophyllene, and guaiacene. In conclusion, passion fruit-roasted chicken contained many characteristic flavor components, which were mainly formed within 15 to 30 min of roasting and were basically stable during the 30-day storage period. In a word, this work prepared a novel roasted chicken and revealed its mechanism of flavor formation at different baking stages and storage periods, which provided references for industrial production.

Comparative transcriptome analysis of longissimus dorsi muscle reveal potential genes affecting meat trait in Chinese indigenous Xiang pig

In this study, we compared the transcriptome of longissimus dorsi muscle between Guizhou Xiang pigs (XP) and Western commercial Large White pigs (LW), which show diffirent meat quality between them. In terms of meat quality traits, the pH 45 min, color score, backfat thickness, and intramuscular fat (IMF) content were higher in Xiang pigs than in Large White pigs (P < 0.01), while the drip loss, lean meat percentage, shear force, and longissimus dorsi muscle area of Xiang pigs were lower than that of Large White pigs (P < 0.01). Nutrients such as monounsaturated fatty acid (MUFA), total amino acids (TAA), delicious amino acids (DAA) and essential amino acids (EAA) in Xiang pigs were higher than that in Large White pigs, and the proportion of polyunsaturated fatty acid (PUFA) of Xiang pigs was significantly lower than Large White pigs (P < 0.01). Transcriptome analysis identified 163 up-regulated genes and 88 genes down-regulated in Xiang pigs longissimus dorsi muscle. Combined with the correlation analysis and quantitative trait locis (QTLs) affecting meat quality, a total of 227 DEGs were screened to be significantly associated with meat quality values. Enrichment analysis indicated that numerous members of genes were gathered in muscle development, adipogenesis, amino acid metabolism, fatty acid metabolism and synthesis. Of those, 29 genes were identified to be hub genes that might be related with the meat quality of Xiang pig, such as MYOD1, ACTB, ASNS, FOXO1, ARG2, SLC2A4, PLIN2, and SCD. Thus, we screened and identified the potential functional genes for the formation of meat quality in Xiang pigs, which provides a corresponding theoretical basis for the study of the molecular regulatory mechanism of pork quality and the improvement of pork quality.

Effects of cooking methods on aroma formation in pork: A comprehensive review

Pork is widely consumed and appreciated by consumers across the world, and there are various methods of cooking pork. This study aimed to summarize the effects of different heat transfer media on pork flavor and the sources of flavor compounds. The cooking methods are classified based on the heat transfer media used, which include water and steam (e.g. steaming, boiling, and stewing), heat source or hot air (e.g. baking and smoking), oil (e.g. pan-frying, stir-frying, and deep frying), and other cooking technologies. The objective is to provide a reference for researchers studying pork cooking methods and flavor components.

Mechanisms of cooking methods on flavor formation of Tibetan pork

To obtain flavor-enriched Tibetan pork products, the impact of oxidation degree on the flavor of Tibetan pork with different cooking methods (microwaving, frying, boiling, and air frying) was evaluated using an E-nose, an E-tongue, GC-MS, and LC-MS. The level of oxidation was lower in M and F and higher in B and AF groups. Hexanal, pentanal, benzaldehyde, 1-octen-3-ol, and 3-hydroxy-2-butanone were identified as significant contributors to cooked samples. The volatile abundance of microwaved, fried, boiled, and air-fried pork was 1.61, 1.22, 1.47, and 1.69 times higher than raw, respectively. Leucine and threonine were detected to be the highest in the AF group, which were 1.30 and 3.60 times greater than RAW, respectively. In summary, oxidation of lipids and proteins caused by cooking treatments was the main source of flavor in cooked Tibetan pork. Air-frying treatment could greatly promote the production of flavor compounds and give unique flavor to Tibetan pork.

A Specific microRNA Targets an Elongase of Very Long Chain Fatty Acids to Regulate Fatty Acid Composition and Mitochondrial Morphology of Skeletal Muscle Cells

Recently, miR-22 has been suggested to be an important microRNA (miRNA) affecting meat quality. Studies have shown that muscle fatty acid composition and mitochondrial function are closely related to meat quality. The regulatory mechanism of miR-22 on skeletal muscle fatty acid composition and mitochondrial function is not well characterized. Therefore, we aimed to explore the effects of miR-22 on fatty acid composition and mitochondrial function in C2C12 cells. Here, it demonstrate that elevated expression of miR-22 significantly repressed fatty acid elongation and mitochondrial morphology in C2C12 myoblasts, while the knockdown of miR-22 showed opposite results. Furthermore, miR-22 targets the elongase of very long chain fatty acids 6 (ELOVL6) and represses its expression in muscle cells. Knockdown of ELOVL6 mimicked the effect of miR-22 on fatty acid composition and mitochondrial function, while overexpression of ELOVL6 restored the effects of miR-22. These findings indicate that miR-22 downregulates the elongation of fatty acids and mitochondrial morphology by inhibiting ELOVL6 expression in muscle cells, which may provide some useful information for controlling muscle lipid accumulation and mitochondrial function in livestock in the future.

Investigation of Physicochemical and Sensory Quality Differences in Pork Belly and Shoulder Butt Cuts with Different Quality Grades

The objective of this study was to investigate the effects of quality grade (QG) on the physicochemical composition and eating quality attributes of pork belly and shoulder butt. Seventy-two growing-finishing crossbred pigs were slaughtered and their carcasses were graded according to the Korean pork carcass grading system. Based on the grading criteria, the carcasses were classified into: QG 1⁺ (n=23), QG 1 (n=23) and QG 2 (n=26) groups. At 24 h postmortem, belly and shoulder butt cuts were collected from the QG groups and used for analysis of meat quality, flavor compounds and eating quality attributes. Results showed that the variation in fat content among QG was approximately 2% in the both cut types. The QG showed no effects on all the quality traits: cooking loss, pH and color of the belly or shoulder butt (p>0.05). Thirty-five flavor compounds comprising mainly fatty acids oxidation/degradation-derived products (e.g., aldehydes) and only few Maillard reaction-derived products (e.g., sulfur-and nitrogen-containing compounds) were identified. However, the QG showed a minor effect on the flavor profiles in both the belly and shoulder butt. Regarding the sensory quality, no effects of the QG were found on all the eating quality attributes (color, flavor, juiciness, tenderness and acceptability) for both the belly and shoulder butt cuts (p>0.05). Thus, it may be concluded that the current pork carcass grading standards do not reflect the real quality and value of the belly and shoulder butt cuts.

Comparative effects of dietary microalgae oil and fish oil on fatty acid composition and sensory quality of table eggs

This study was conducted to investigate the comparative effects of dietary supplementation with microalgae oil or fish oil on fatty acid composition, sensory quality, and overall acceptability of table eggs. A total of six hundred thirty, 30-week-old, Hy-Line Brown laying hens were allocated to 7 dietary treatments. Layers were fed with a control diet or the control diet supplemented with graded levels of docosahexaenoic acid (DHA; 1.25, 2.50, and 5.00 mg/g feed) derived from microalgae oil or fish oil. The feeding trial lasted 10 wk. Enrichment of eggs with DHA by dietary supplementation with microalgae oil or fish oil enhanced yolk DHA and total n-3 polyunsaturated fatty acid (PUFA) enrichment and reduced n-6-to-n-3 ratio in a dose-response manner, whereas the efficiency decreased (P < 0.05). The overall efficiency of DHA incorporation into eggs was similar for the 2 sources (P > 0.05). In comparison with fish oil, dietary microalgae oil supplementation resulted in higher scores for egg flavor and overall acceptability, both of which declined linearly in response to DHA supplementation (P < 0.05). Among the aroma and flavor characteristics, fishy aroma and flavor scores increased linearly and quadratically (P < 0.05) in response to dietary DHA supplementation, and egg aroma and flavor and milky flavor scores decreased linearly (P < 0.05). The results from partial least squares analysis showed that fishy flavor and aroma were closely associated with DHA, α-linolenic acid, and total n-3 PUFA, and oleic acid, arachidonic acid, and dihomo-gamma-linolenic acid were more related to egg aroma and flavor. The results suggested that microalgae oil would be more promising for egg DHA enrichment owing to better sensory quality of the resultant eggs.

GC-O-MS technique and its applications in food flavor analysis

Gas chromatography-olfactometry-mass spectrometry (GC-O-MS) is a combination of gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS). GC-O-MS technique is a powerful tool to study food flavors and it has been widely applied for aroma and flavor analysis of various food items. In combination with different technologies, GC-O-MS can be applied to solve many flavor problems in the food industry such as quick mapping of aroma-active compounds, identification of key aroma-active compounds, cluster analysis based on the aroma-active compounds, relationship between odorants and sensory properties, and clarification of formation mechanism of important odorants. The newly proposed "molecular sensory science" concept (or sensory-directed flavor analysis) provides a much deeper research for the GC-O-MS application. Here, we have reviewed the operation, advantages and applications of GC-O-MS technique. Qualitative/quantitative analysis methods and sampling methods of aroma-active compounds have been described to introduce the different application areas of GC-O-MS. Case studies based on existing papers and our research have been discussed.

Flavour development in pork. Influence of flavour precursor concentrations in longissimus dorsi from pigs with different raw meat qualities

Flavour development and overall eating quality of pan-fried pork chops of longissimus dorsi from eight different raw meat qualities aged for 4 and 15 days were assessed by a trained sensory panel. The raw meat qualities were obtained through combinations of strategic feeding/fasting (control vs. low glycogen concentration), slaughter live-weight (84kg vs. 110kg), and gender (female vs. castrate). The flavour development was investigated for possible correlation with the concentrations of selected individual flavour precursors present in the raw meat: monosaccharides, IMP and degradation products, fatty acids, lactate and thiamine. Differences in precursor concentrations between the raw meat qualities were observed with feeding/fasting and ageing as the main factors with the largest influence of all experimental factors. However, the concentrations of the precursors could not explain the differences in sensory perception of the pan-fried pork chops. Overall, the differences were small.