Volatile flavours in raw egg yolk of hens fed on different diets

Evaluation of deodorization techniques using cyclodextrins on the headspace volatiles and antioxidant properties of onion

Sulphur-containing volatiles in onion produce unpleasant odors and this limit their usage in foods. To expand its application, several additives including α-cyclodextrin (α-CD), β-cyclodextrin (β-CD), 2-hydroxypropyl-β-cyclodextrin (HP-β-CD), and chitosan were added to onion solution and evaluated for their effect on sulphur-containing volatiles. Also, antioxidant property using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and oxidative stabilities in an oil-in-water (O/W) emulsion were carried out. The total volatile contents were decreased in the order of α-CD (50.1%), β-CD (49.3%), HP-β-CD (46.2%), and chitosan (7%). Meanwhile, HP-β-CD showed the highest DPPH radical scavenging ability followed by β-CD, α-CD, and chitosan with decreasing order. The β-CD significantly enhanced the oxidative stability of the O/W emulsion, whereas α-CD and β-HP-CD showed prooxidative behavior. Overall, β-CD might be used as a sulphur-containing volatile decreasing agent, which could keep the antioxidant properties of onion in the O/W emulsion.

A Comparison between the Egg Yolk Flavor of Indigenous 2 Breeds and Commercial Laying Hens Based on Sensory Evaluation, Artificial Sensors, and GC-MS

The focus of this study was to compare the yolk flavor of eggs from laying hens of Chinese indigenous and commercial, based on detection of volatile compounds, fatty acids, and texture characteristics determination, using sensory evaluation, artificial sensors (electronic nose (E-nose), electronic tongue (E-tongue)), and gas chromatography-mass spectrometry (GC-MS). A total of 405 laying hens (Hy-Line Brown (n = 135), Xueyu White (n = 135), and Xinyang Blue (n = 135)) were used for the study, and 540 eggs (180 per breed) were collected within 48 h of being laid and used for sensory evaluation and the instrument detection of yolk flavor. Our research findings demonstrated significant breed differences for sensory attributes of egg yolk, based on sensory evaluation and instrument detection. The milky flavor, moisture, and compactness scores (p < 0.05) of egg yolk from Xueyu White and Xinyang Blue were significantly higher than that of Hy-Line Brown. The aroma preference scores of Xinyang Blue (p < 0.05) were significantly higher, compared to Hy-Line Brown and Xueyu White. The sensor responses of WIW and W2W from E-nose and STS from E-tongue analysis were significantly higher foe egg yolks of Hy-Line Brown (p < 0.05), compared to that of Xueyu White and Xinyang Blue. Additionally, the sensor responses of umami from E-tongue analysis, was significantly higher for egg yolks of Xueyu White (p < 0.05), compared to that of Hy-Line Brown and Xinyang Blue. Besides, the contents of alcohol and fatty acids, such as palmitic acid, oleic acid, and arachidonic acid, in egg yolk were positively correlated with egg flavor. The texture analyzer showed that springiness, gumminess, and hardness of Hy-Line Brown and Xueyu White (p < 0.05) were significantly higher, compared to Xinyang Blue. The above findings demonstrate that the egg yolk from Chinese indigenous strain had better milky flavor, moisture, and compactness, as well as better texture. The egg yolk flavors were mainly due to presence of alcohol and fatty acids, such as palmitic acid, oleic acid, and arachidonic acid, which would provide research direction on improvement in egg yolk flavor by nutrition. The current findings validate the strong correlation between the results of egg yolk flavor and texture, based on sensory evaluation, artificial sensors, and GC-MS. All these indicators would be beneficial for increased preference for egg yolk flavor by consumers and utilization by food processing industry, as well as a basis for the discrimination of eggs from different breeds of laying hens.

Characterization of Volatile Profiles and Correlated Contributing Compounds in Pan-Fried Steaks from Different Chinese Yellow Cattle Breeds through GC-Q-Orbitrap, E-Nose, and Sensory Evaluation

This study focused on characterizing the volatile profiles and contributing compounds in pan-fried steaks from different Chinese yellow cattle breeds. The volatile organic compounds (VOCs) of six Chinese yellow cattle breeds (bohai, jiaxian, yiling, wenshan, xinjiang, and pingliang) were analyzed by GC-Q-Orbitrap spectrometry and electronic nose (E-nose). Multivariate statistical analysis was performed to identify the differences in VOCs profiles among breeds. The relationship between odor-active volatiles and sensory evaluation was analyzed by partial least square regression (PLSR) to identify contributing volatiles in pan-fried steaks of Chinese yellow cattle. The results showed that samples were divided into two groups, and 18 VOCs were selected as potential markers for the differentiation of the two groups by GC-Q-Orbitrap combined multivariate statistical analysis. YL and WS were in one group comprising mainly aliphatic compounds, while the rest were in the other group with more cyclic compounds. Steaks from different breeds were better differentiated by GC-Q-Orbitrap in combination with chemometrics than by E-nose. Six highly predictive compounds were selected, including 3-methyl-butanal, benzeneacetaldehyde, 2-ethyl-6-methyl-pyrazine, 2-acetylpyrrole, 2-acetylthiazole, and 2-acetyl-2-thiazoline. Sensory recombination difference and preference testing revealed that the addition of highly predictive compounds induced a perceptible difference to panelists. This study provides valuable data to characterize and discriminate the flavor profiles in pan-fried steaks of Chinese yellow cattle.

Characterisation of Flavour Attributes in Egg White Protein Using HS-GC-IMS Combined with E-Nose and E-Tongue: Effect of High-Voltage Cold Plasma Treatment Time

Egg white protein (EWP) is susceptible to denaturation and coagulation when exposed to high temperatures, adversely affecting its flavour, thereby influencing consumers' decisions. Here, we employ high-voltage cold plasma (HVCP) as a novel nonthermal technique to investigate its influence on the EWP's flavour attributes using E-nose, E-tongue, and headspace gas-chromatography-ion-mobilisation spectrometry (HS-GC-IMS) due to their rapidness and high sensitivity in identifying flavour fingerprints in foods. The EWP was investigated at 0, 60, 120, 180, 240, and 300 s of HVCP treatment time. The results revealed that HVCP significantly influences the odour and taste attributes of the EWP across all treatments, with a more significant influence at 60 and 120 s of HVCP treatment. Principal component analyses of the E-nose and E-tongue clearly distinguish the odour and taste sensors' responses. The HS-GC-IMS analysis identified 65 volatile compounds across the treatments. The volatile compounds' concentrations increased as the HVCP treatment time was increased from 0 to 300 s. The significant compounds contributing to EWP characterisation include heptanal, ethylbenzene, ethanol, acetic acid, nonanal, heptacosane, 5-octadecanal, decanal, p-xylene, and octanal. Thus, this study shows that HVCP could be utilised to modify and improve the EWP flavour attributes.

Thymol and carvacrol supplementation in poultry health and performance

BACKGROUND

Thymol and carvacrol as natural essential oils and phenol compounds are components derived from some medicinal plants, such as thyme and oregano species.

OBJECTIVES

The increasing demands in organic and healthy meat and egg consumption in human society have made it necessary to consider alternative natural compounds for the replacement of chemical compounds in poultry production. The chemical compounds can remain in meat and eggs and cause complications in human health. Therefore, these natural compounds can be fed with a higher safety in poultry production with specific effects. In this regard, the role of thymol and carvacrol as natural compounds in the poultry production has been discussed in the review.

METHODS

In this study, by searching for keywords related to thymol and carvacrol in poultry production in Google Scholar database, the articles related to different aspects of the biological effects of these two phytogenes in poultry production were selected and analyzed.

RESULTS

A review of previous studies has shown that thymol and carvacrol possess a wide range of biological activities, including antibacterial, antiviral, antioxidant, anti-inflammatory, modulating of immunity response and regulating of the gut microbial population. Also, in meat type chickens can promote growth and influence feed utilization. The beneficial effect of this compound was evaluated in hepatic toxicity and demonstrated as a hepatoprotective compound in chickens. Furthermore, these compounds can affect the behavior of layers and influence egg composition, eggshell thickness, and the sensory quality of eggs.

CONCLUSION

It seems that with the increasing demand for healthy protein products, these compounds can be used to improve performance as a substitute alternative for chemical compounds in healthy poultry farms.

Flavor Characterization of Animal Hydrolysates and Potential of Glucosamine in Flavor Modulation

Bovine (meat and heart) and porcine (hemoglobin and plasma) raw materials were hydrolyzed by Protease A (both endo- and exopeptidase activity), with or without glucosamine added during the enzyme inactivation step. Hydrolysates were characterized via peptide analysis (yield, UV- and fluorescence scanning spectroscopy, and peptide size distribution via size exclusion chromatography), sensory evaluation, and volatile compound analysis via gas chromatography mass-spectrometry (GC-MS) to determine if glucosamine-induced Maillard reaction improved taste and flavor. Porcine hemoglobin produced the most flavor-neutral hydrolysate, and could expectedly have the broadest application in food products. Both bovine meat and -heart hydrolysates were high in umami, and thereby good candidates for savory applications. Porcine plasma hydrolysate was high in liver flavor and would be suitable for addition to certain meat products where liver flavor is desirable. All hydrolysates had low perceived bitterness. Glucosamine-induced Maillard reaction had just a minor influence on the sensory profile via an increased perception of sweet taste (p = 0.038), umami taste (p = 0.042), and yolk flavor (p = 0.038) in the hydrolysates, irrespective of raw material. Glucosamine addition had a statistically significant effect on 13 of 69 volatiles detected in the hydrolysates, but the effect was minor and raw material-specific.

Effects of temperature on quality of preserved eggs during storage

The effects of storage temperature (4°C, 25°C, and 35°C) on sensory quality, physicochemical properties, texture, molecular forces, flavor, and microbial indexes of preserved eggs were studied. The results showed that the sensory quality, weight loss rate, pH, and color of preserved eggs were significantly different at different storage temperatures (P < 0.05). Compared with high temperature and normal temperature storage, low temperature storage reduced weight loss rate by 55.15 and 64.1%, respectively, improved the sensory score (P < 0.05), inhibited the reduction of pH and the increase of total volatile base nitrogen (P < 0.05), and decreased the change of color (P < 0.05). During storage, there was no difference in the springiness of preserved egg white stored at different temperatures (P > 0.05). Hardness and chewiness at 3 different temperatures increased first and then decreased, and low temperature significantly inhibited the progress of these changes to a certain extent (P < 0.05). The content of ionic bond in egg white first decreased and then increased, and content of disulfide bond increased first and then decreased. Content of ionic bond in yolk decreased all the time, and high temperature could promote this change. Whatever the temperature was, the content of free amino acids in preserved egg white and yolk increased first and then decreased, and the total content of amino acids stored at different temperatures was significantly different (P < 0.05). The content of free fatty acids in yolk decreased. At the end of storage, no microorganisms were detected in 3 temperatures during the storage period of 84 D. The results showed that low temperature storage is more conducive for preservation of preserved eggs.

Chemical-Sensory Traits of Fresh Cheese Made by Enzymatic Coagulation of Donkey Milk

Making cheese from donkey milk is considered unfeasible, due to difficulties in coagulation and curd forming. Two recent studies have reported the protocols for making fresh cheese by using camel chymosin or calf rennet, but the chemical and sensory characteristics of the products were not thoroughly investigated. The present paper aims to give a further contribution to the field, by investigating cheesemaking with microbial rennet and evaluating the chemical composition, total fatty acid, volatile organic compounds (VOCs) and sensory profile of the resultant product. Six trials were undertaken at laboratory scale on donkey milk from a Martina Franca ass, by applying the technological scheme as reported for calf rennet, with some modifications. Bulk cow milk was used as a control. Donkey milk coagulated rapidly, but the curd remained soft, and was only suitable for making fresh cheese; differently, cow milk coagulated almost instantaneously under these strong technological conditions, giving rise to a semi-hard curd in very short time. The moisture level of donkey cheese was almost the same as reported in the literature, whereas the yield was higher, probably due to the high protein content of the milk used. The total fatty acid composition of cheese presented some differences with respect to milk, mostly consisting in a higher presence of saturated compounds. A connection with a better retention of the large sized fat globules into the curd was hypothesised and discussed. The VOC analyses, performed by solid-phase micro extraction gas chromatography-mass spectrometry, allowed the identification of 11 compounds in milk and 18 in cheese. The sensory characteristics of donkey cheese were strongly different with respect to the control, and revealed unique and pleasant flavours.

Characterization of key aroma-active compounds in four commercial egg flavor Sachimas with differing egg content

To characterize the aroma components of Sachima and provide insight into the influence of egg on the flavor of Sachima, the key aroma-active compounds in four commercial egg flavor Sachimas with different egg content, which named Premium, Classical, Whole egg, and Egg yolk, were identified using GC-MS-O analysis, aroma extract dilution analysis (AEDA) combined with sensory evaluation. In total, 75 volatile compounds were identified by GC-MS, including 26 compounds were revealed of having aroma activities by AEDA/GC-O. The major volatile compounds in Sachima were the aldehydes and heterocyclic compounds. The OAV further revealed the significant activity of eight key aroma-active compounds include 2-methylbutanal, 3-methylbutanal, hexanal, n-propylacetate, 2-pentylfuran, 2-ethylpyrazine, nonanal, and benzaldehyde. The OAV of 2-methylbutanal and 3-methylbutanal were much higher in Premium sample that has the most egg content, than that in other samples, whereas hexanal was the highest in Whole egg samples. The plot analyzed by PLS suggest that the Premium sample with more egg content was shown more complicated flavor than other kind of Sachima. Practical applications Sachima is a type of famous sweet Chinese traditional pastries. The flavor and texture of this kind of pastry were appreciated by all age group, especially for almost all elderly Chinese. Because Sachima is not only a suitable food that easy to chew, but a type of food which filled with childhood memory. Egg flavor of Sachima was always the most popular and classic flavor category. However, the characteristic aroma compounds of Sachima-one of the most important factor of the Sachima's quality-have been still uncovered and had not been identified yet, not to mentioned the comparison between different egg content in Sachima. What's more, GC-MS-O/AEDA analysis has been always a very effect and well-known method for aroma compounds analysis. This study trying to find the contribution of eggs to Sachima and the key aroma-active compounds of Sachima, so as to provide some useful information for practical production and flavor quality improving.

Characterization of Potent Aroma Compounds in Preserved Egg Yolk by Gas Chromatography-Olfactometry, Quantitative Measurements, and Odor Activity Value

To characterize potent odor-active compounds in preserved egg yolk (PEY), volatile compounds were isolated by headspace solid-phase microextraction and solvent-assisted flavor evaporation. Gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS) analyses identified a total of 53 odor-active compounds by comparing the odor characteristics, MS data, and retention indices with those of reference compounds. Twenty-seven odorants were detected in at least five isolates that were extracted and analyzed by the same method, and their flavor dilution (FD) factors, ranging from 1 to 2048, were measured by aroma extract dilution analysis (AEDA). To further determine their contribution to the overall aroma profile of PEY, 22 odorants with FD factors ≥16 and GC-MS responses were quantitated, and their odor activity values (OAVs) were calculated. According to the OAV results, 19 odorants with OAVs ≥ 1 are the potent odorants that greatly contribute to the characteristic aroma of PEY. Nine compounds were identified for the first time: (E,Z)-2,6-nonadienal, (E)-2-nonenal, 2-methylbutanal, dimethyl disulfide, trimethylamine, methional, dimethyl trisulfide, diisopropyl disulfide, and diethyl disulfide.

Volatile composition and sensory characteristics of onion powders prepared by convective drying

Volatile composition and sensory characteristics of onion powders prepared by convective drying at different temperatures (50, 70, and 90°C) were investigated. Dipropyl disulfide was the major volatile compound in fresh onion (77.70% of total volatile compounds). However it was considerably lost during drying, reaching 6.93-32.25µg/g solids. Dipropyl disulfide showed a positive correlation with green sensory attribute perceived by descriptive sensory analysis. Thiophenes, which were responsible for caramel and sweet attributes, were produced by drying especially when the drying temperature was high. Aldehydes, another type of volatile compound found in fresh onion, showed a positive correlation with humidity. The aldehyde content in dried onion was the highest at the lowest drying temperature, possibly because the aldehydes were produced by the residual enzymes in fresh onion. Using a low temperature for drying was ideal to retain the aroma of fresh onion.

Metabolic fingerprint of dimethyl sulfone (DMSO2) in microbial-mammalian co-metabolism

There is growing awareness that intestinal microbiota alters the energy harvesting capacity of the host and regulates metabolism. It has been postulated that intestinal microbiota are able to degrade unabsorbed dietary components and transform xenobiotic compounds. The resulting microbial metabolites derived from the gastrointestinal tract can potentially enter the circulation system, which, in turn, affects host metabolism. Yet, the metabolic capacity of intestinal microbiota and its interaction with mammalian metabolism remains largely unexplored. Here, we review a metabolic pathway that integrates the microbial catabolism of methionine with mammalian metabolism of methanethiol (MT), dimethyl sulfide (DMS), and dimethyl sulfoxide (DMSO), which together provide evidence that supports the microbial origin of dimethyl sulfone (DMSO2) in the human metabolome. Understanding the pathway of DMSO2 co-metabolism expends our knowledge of microbial-derived metabolites and motivates future metabolomics-based studies on ascertaining the metabolic consequences of intestinal microbiota on human health, including detoxification processes and sulfur xenobiotic metabolism.

Maternal diet influences offspring feeding behavior and fearfulness in the precocial chicken

Background

In chicken, oils in the maternal diet confer a specific scent to the yolk. Embryos are known to perceive and memorize chemosensory signals of the surrounding environment; however, the potential impact of the maternal diet has not previously been investigated. In the present study, we hypothesized that chicken embryos memorize the chemical signals of the maternal diet and that this perceptual learning may orient subsequent feeding behavior of the hatchlings.

Methodology/Principal Findings

Laying hens were fed standard food enriched with 2% menhaden oil (MH group) or 2% soybean oil (controls). The scent of menhaden was significantly more detected in MH egg yolks than in control yolks by a human panel. We analyzed the development and behavior of offspring towards different types of food, bearing or not bearing the menhaden scent. When chicks were exposed to a 3-min choice test between the familiar food bearing the menhaden scent and the familiar food without menhaden, no effect of treatment was observed. In a 3-min choice test with unfamiliar food (mashed cereals) MH chicks showed a clear positive orientation toward the unfamiliar food bearing the menhaden scent. By contrast, control chicks showed a preference for the non-odorized unfamiliar food. MH chicks expressed higher emotional reactivity level than control chicks as expressed by food neophobia and longer immobility in a restraint test.

Conclusion/Significance

Chicks exposed in ovo to menhaden oil via the maternal diet preferentially oriented their feeding behavior towards food containing menhaden oil, but only when the food was unfamiliar. We propose that oil in the maternal diet engenders maternal effects and contributes to the development of behavioral phenotype in the offspring. In ovo chemosensory learning may have evolved to prepare precocial offspring for their environment. This suggests a common principle of embryonic chemosensory learning across vertebrate taxa.