Metabolomic and proteomic profiling reveals the formation mechanism of volatile flavor in egg whites during fermentation by Streptococcus thermophilus

In this study, the flavor of egg whites was significantly improved by lactic acid fermentation, and the metabolic networks of metabolites, volatile compounds, and enzymes were established using gas chromatography-mass spectrometry, metabolomic, and proteomic. Results indicate that among ten types of common lactic acid bacteria, Streptococcus thermophilus endowed egg white with the most pleasant flavor through increasing aldehydes, ketones, alcohols, esters, terpenoids, and aromatic compounds. Amino acid catabolism was the predominant pathway for generating most aldehydes, alcohols, acids, and esters. The changes in the organic acids and derivatives (mainly amino acids, peptides, and analogues) concentration during fermentation are attributed to the hydrolysis of egg white proteins by proteinases and peptidases, and the regulation of enzymes involved in amino acid biosynthesis and other reactions. This study provides a valuable reference for future investigations focusing on regulating the flavor release of egg whites.

Novel Photodynamic Inactivation Strategy for Salmonella Enteritidis PT4 on Eggshells: Exploiting the Antimicrobial Potential of Curcumin and Carvacrol

Photodynamic inactivation (PDI) is a new and promising strategy for eliminating foodborne pathogenic bacteria in food preservation, reducing associated health risks for consumers. This study aimed to develop an innovative PDI-based system to inactivate Salmonella Enteritidis PT4 on eggshells. The system includes 405 nm light-emitting diodes (LEDs) and the application of curcumin or carvacrol as photosensitizers. The antibacterial activity of the system was investigated in eggshells inoculated with S. Enteritidis PT4 at different temperatures (4, 25, and 37°C) and exposure times (15, 30, and 45 min). Carvacrol + LEDs application was completely inhibited S. Enteritdis PT4 at 4 (after 30 min), 25, and 37°C at the 45th min. Curcumin + LED completely inhibited bacterial growth after 45 min at 4 and 25°C. The results showed that simultaneous use of carvacrol or curcumin with LEDs at various temperatures exhibited significant antibacterial activity against the bacteria depending on the exposure time. The application of curcumin or carvacrol sourced via PDI in the originally developed system resulted in any significant changes in egg quality parameters and sensory properties. This study demonstrated that PDI-based system using curcumin or carvacrol as photosensitizers could be a potential tool for decontamination of eggs contaminated with S. Enteritidis PT4.

Orychophragmus violaceus and/or chicory forage affects performance, egg quality, sensory evaluation and antioxidative properties in native laying hens

Orychophragmus violaceus (OV) and chicory (Cichorium intybus L., CC) can be used as fresh or dry forage for animals. To determine whether OV and/or CC have beneficial effects on performance and egg quality, a total of 1212 28-wk-old Beijing You Chicken (BYC) laying hens with similar performance were randomly allocated to 4 groups with 3 replicate pens per group, and 101 birds per pen. The birds were fed a basal diet (control), the basal diet + OV (3.507 kg/d/pen), the basal diet + CC (2.525 kg/d/pen), and the basal diet + OV + CC (OVC, 1.7535 kg/d/pen OV + 1.2625 kg/d/pen CC) for 3 wks after one wk of adaptation. The results showed that egg-laying rate was not affected by OV, CC and OVC (p > 0.05), but weekly average egg mass was significantly increased by OV and CC (p < 0.05). The feed egg ratio in the CC group (2.82) was significantly lower than that in the other three groups (p < 0.05). The eggshell thickness (EST), albumen height (AH) and Haugh unit (HU) were decreased by OV and CC (p < 0.05); while yolk color (YC) was increased in the CC and OVC groups (p < 0.05). Egg grade was decreased by OV (p < 0.05). Sensory evaluation showed that there was a trend for increased YC in OV, CC and OVC (p = 0.089). Serum total protein was significantly lower in OV group than those in the control and CC group (p < 0.05); serum albumin content was significantly decreased in OV, CC and OVC groups (p = 0.006). Serum glutathione peroxidase activity in CC and OVC groups was significantly higher than that in the control group (p < 0.05). In conclusion, the present study suggests that CC had a better effect on the performance of the native laying hens than OV. The OV and CC affected egg quality, while YC was increased in CC and OVC groups. The OVC improved YC and serum antioxidative properties of native laying hens without affecting the performance.

Egg Quality, Sensory Attributes, and Protein Metabolites of Laying Hens Fed Whole Flaxseed, Fish Oil, and Different Sources of Trace Elements

This study evaluated the effects of whole flaxseed (WFS), fish oil (FO), and different sources of Se, Zn, and Fe (inorganic, organic, and nano-source) on egg production, quality, sensory attributes, and serum protein metabolites in laying hens. A total of 144 hens were divided into six groups with six replicates of four hens each. Hens were fed six diets as follows: 1) control diet; 2) 7.5%WFS+1.5%FO; 3) 7.5%WFS+1.5%FO+175 mg/kg vitamin E (VE); 4) 7.5%WFS+1.5%FO+175 mg/kg VE + inorganic sources of Se, Zn, and Fe (ISeZnFe); 5) 7.5%WFS+1.5%FO+175 mg/kg VE + organic sources of Se, Zn, and Fe (OSeZnFe); 6) 7.5%WFS+1.5%FO+175 mg/kg VE + nano-source of Se, Zn, and Fe (NSeZnFe) from 40-50 weeks of age. Laying hens fed 7.5% WFS, 1.5% FO, and different sources of trace elements in their diets had no negative effects on laying rate, egg weight, egg mass, feed intake, feed conversion ratio, body weight change, or survival rate compared to that of hens fed the control diet. Dietary treatments did not negatively affect the external and internal egg characteristics or egg sensory attributes. Feeding 7.5%WFS+1.5%FO+VE+ISeZnFe positively influenced yolk color in fresh eggs. Dietary treatments had a significant impact on egg nutritional composition, with the highest levels of macronutrients found in eggs from hens fed the 7.5%WFS+1.5%FO+VE+NSeZnFe treatment. The highest plasma globulin concentrations were observed in hens fed organic and nano-source trace elements. The same diets reduced plasma uric acid levels. Based on these findings, the inclusion of organic or nano-source trace minerals in diets containing WFS and FO positively affected egg quality and hen protein metabolites.

Antioxidant Status, Lipid Metabolism, Egg Fatty Acids, and Nutritional Index of White-Egg Laying Hens Fed Flaxseed Cake

Flaxseed cake contains high levels of phenolic compounds, which have numerous biological activities, as well as a considerable amount of omega-3 fatty acids, such as α-linolenic acid, which remains after oil extraction. In this study, we examined the effects of flaxseed cake meal (FSCM) on the antioxidative status, lipid metabolism, egg fatty acid profile, and egg health index of white-egg laying hens. A total of 63 Hisex White laying hens were divided into three experimental treatment groups and fed diets containing 0, 5, or 10% FSCM from 48 to 58 weeks of age. Feeding with 5 and 10% FSCM did not significantly (p>0.05) influence total lipid, triglyceride, total cholesterol, very low-density lipoprotein-cholesterol, or low-density lipoprotein-cholesterol concentrations, or the high-/low-density lipoprotein ratio in the serum and egg yolk; however, 10% FSCM significantly (P<0.05) increased serum high-density lipoprotein. Dietary FSCM also did not affect (P>0.05) antioxidant markers in the eggs and blood plasma. Notably, dietary inclusion of FSCM significantly increased (P<0.05) total n-3 polyunsaturated fatty acids (PUFAs), α-linolenic acid, docosahexaenoic acid, and eicosapentaenoic acid levels in egg yolk, whereas the n-6:n-3 PUFAs ratio was markedly (P<0.05) decreased in a dose-dependent manner. Moreover, including 5-10% FSCM improved (P<0.05) egg health indices, with 10% being the most beneficial. Together, these findings indicated that the inclusion of up to 10% FSCM in laying hen diets improved egg yolk lipid and fatty acid profiles, as well as egg quality and nutritional and metabolic indices.

Dietary flaxseed cake influences on performance, quality, and sensory attributes of eggs, serum, and egg trace minerals of laying hens

Nowadays, there is a global shortage in feed supply for animal nutrition; however, there are a considerable amount of agro-industrial co- and by-products that may offer a reasonable solution. Flaxseed cake (FSC) is a by-product of flaxseed for oil extraction rich in n-3 α-linolenic acid (ALA). Thus, the dietary inclusion of FSC on laying performance, egg quality, and serum and egg trace elements (Se, Zn, and Fe) was evaluated using Hisex White hens. The hens were distributed to three equal experimental treatments and provided diets including 0%, 5%, or 10% FSC from 48 to 58 weeks of age. Findings clarified that up to 10% FSC in the laying hen diet had no detrimental effect on laying rate, egg mass, and feed utilization. It was found that FSC resulted in a valuable source of protein, energy, macro- (Ca and P), micro- (Se, Zn and Fe) elements, and essential amino acids, with arginine being the highest. Dietary FSC did not negatively influence the egg quality traits, as well as egg sensory attributes. Including 5% or 10% FSC in diet did not significantly affect serum total protein and renal function in terms of creatinine, uric acid, and uric acid-to-creatinine ratio. Different FSC levels did not influence the chemical composition of eggs and trace elements in serum and eggs. It could be concluded that FSC is a valuable feedstuff that can provide a good source of energy, protein, amino acids, and macro- and micro-elements for hens' nutrition. The inclusion of up to 10% of FSC in hens diet did not adversely influence egg laying performance, egg quality of both fresh and stored eggs, sensory attributes, and nutritional composition, as well as Se, Zn, and Fe in serum and eggs due to balanced nutrient profile of FSC.

Combination of sensory evaluation with conventional physiochemical analyses to evaluate quality changes during long-term storage and estimate the shelf life of chicken eggs

1. This study developed a comprehensive sensory evaluation system that consisted of descriptions corresponding to United States Department of Agriculture photos to evaluate overall acceptability, albumen and yolk appearances and odours. It determined physiochemical parameters of eggs stored at 7°C (7W12 and 7U12 for washed and unwashed, respectively) for 12 weeks and stored at 25°C (25W4 and 25U4 for washed and unwashed, respectively) for four weeks.2. Throughout storage, there was a general downward trend in Haugh units (HU) and yolk index and an upward trend in air cell size, weight loss and S-ovalbumin content were observed (P < 0.05). The 25W4 and 25U4 egg quality rapidly deteriorated from grade AA (HU 81.7) to grade B after two weeks (HU 46.5 and 49.6), whereas 7W12 and 7U12 eggs remained grade A after 12 weeks (HU 67.3 and 66.9). High correlations were observed between the sensory and physiochemical parameters (i.e., R2 = 0.93, 0.93, 0.88 and 0.94 for albumen appearance, yolk appearance, sensorial odour and overall acceptability, respectively, with HU in 25W4 eggs).3. Eggs stored at 25°C and classified into 'premium', 'class I', and 'class II' on the basis of their HU had estimated shelf life of 0.5, 1.5 and 2.5 weeks, while shelf lives of 4, 9 and 15 weeks were estimated for 7°C-stored premium, class I and II eggs, respectively.4. In conclusion, distinct HU requirements for eggs of different quality classes under two storage temperatures need to be established. Incorporating sensory evaluation with conventional physiochemical analyses is promising to assess and estimate egg quality changes. Further research work about the influences of different storage temperatures and possible temperature fluctuations during storage on egg quality changes is needed.

Improved biological value of eggs due to the addition of pomegranate seed oil to laying-hen diets

In this study, the effects of the addition of pomegranate seed oil (PSO) at different levels (0, 0.5, 1, and 1.5  mL kg - 1 ) to laying-hen rations on performance values, egg quality criteria, egg shelf life, some enzyme activity, and the fatty acid composition of yolks were investigated. In the study, 96 Lohman LSL laying hens at 64 weeks of age were used. The trial consisted of four groups, each containing 24 hens. Chickens were given feed and water ad libitum during the 8-week experiment. The first group was the control group and was fed with a basal diet, while the other groups were fed with feeds with 0.5, 1.0, and 1.5  mL kg - 1 PSO added to the basal feed, respectively. The lowest feed consumption and the highest egg weight were determined in the 1  mL kg - 1 PSO group. The highest feed conversion ratio, the lowest eggshell weight, and the shell-breaking strength were determined in the 0.5  mL kg - 1 PSO group. It was determined that the egg yolk malondialdehyde (MDA) value in the groups to which pomegranate seed oil was added was significantly lower than the control group on the 28th day of storage. The lowest glutation (GSH) and catalase values were found in the control group, and the highest total antioxidant capacity (TAC) was found in the 1  mL kg - 1 PSO group. It was determined that the addition of PSO to the diet significantly increased the rate of saturated fatty acids (SEFA), conjugated linoleic acid (CLA), and conjugated linolenic acids (CLnA) in yolk. The results showed that the addition of 1  mL kg - 1 pomegranate seed oil to the feeds decreased feed consumption, increased egg weight, and positively affected the shelf life of the egg. In short, the addition of PSO had a positive effect on shelf life, and it increased punicic acid and CLA levels without reducing egg quality.

Evaluating the Effect of a Brewery By-Product as Feed Supplementation on the Quality of Eggs by Means of a Human Panel and E-Tongue and E-Nose Analysis

The objective of our research was to evaluate the possible alteration of the organoleptic properties of eggs produced by hens (Lohmann Brown-Classic) fed with diets containing different doses of an industrial by-product enriched with organic zinc (Zincoppyeast, ZP): Control 0%, ZP 2.5%, and ZP 5.0%. Eggs were collected after 30 days (batch 1) and 60 days (batch 2) of feeding with the experimental diets and subjected to chemical, microbiological, human sensory, e-nose, and e-tongue analyses. There was no significant difference among the microbiological status of eggs of the three groups, but there were significant differences (p < 0.05) in the fat (9.5% vs. 9.3%) and protein contents (12.7% vs. 13.4%) of the Control and ZP 5.0% groups, respectively. Human sensory analysis showed no clear change in the organoleptic characteristics of the eggs. Using linear discriminant analysis (LDA), the e-tongue could recognize the three groups of eggs in batch 1 and batch 2 with 95.9% and 100% accuracy and had a prediction accuracy of 64.8% and 56.2%, respectively. When the eggs were incubating at 50 °C or 80 °C before the e-nose analysis, the groups of eggs could be recognized with 98.0% and 82.7% accuracy, and predicted with 68.5% and 62.2% accuracy, respectively, using principal component analysis-based discriminant analysis (PCA–DA). The aroma compounds and respective sensory descriptors showing changes among the different groups of eggs (batch, storage, and feeding) were identified based on the e-nose analysis. The supplementation of laying hens’ feed with the investigated industrial by-product can be applied without any substantial effect on egg quality, which can, however, be detected with advanced analytical methods.

Egg Quality Parameters, Production Performance and Immunity of Laying Hens Supplemented with Plant Extracts

This study examined the effects of Mentha arvensis (MA) and Geranium thunbergii (GT) extracts in drinking water on the production performance, egg quality, cholesterol content of egg yolk, proximate composition, and sensory qualities of egg and immunity parameters in laying hens. Ninety-six 28-week-old Hy-Line Brown layers were randomly divided into four dietary treatments for 16 weeks. The dietary treatments were (1) control, (2) T1 (0.01% 1 MA:1 GT), (3) T2 (0.05% 1 MA:1 GT), and (4) T3 (0.1% 1 MA:1 GT). Egg production increased significantly with increasing levels of MA and GT. The egg weight was increased in T2, and the feed intake was highest in T2 and T3 (p < 0.05). The Haugh unit and egg shape index were significantly better in T3 and the control than with other treatments (p < 0.05). The content of yolk cholesterol was significantly lower (p < 0.05) in T2 and T3. On the other hand, there were no significant differences in the egg proximate composition. A significant increase in the serum interleukin 6 (IL-6), tumor necrosis factor (TNFα) and immunoglobulins (IgG and IgA) concentration was observed in the birds fed plant extracts when compared to the control. On average, T2 and T3 showed significantly lower (p < 0.05) concentrations of NH3 gas from the feces as compared to the control. This study suggests that MA and GT supplementation could improve the laying performance, egg quality, and immunity, and decrease the egg yolk cholesterol content in a dose-dependent manner.

Consumer preferences and sensory characteristics of eggs from family farms

The objective of this study was to evaluate consumer habits as well as the sensory perception and characteristics of farm eggs produced in Los Ríos, Chile. Data were collected from an online survey of 197 respondents and a sensory evaluation carried out by 30 untrained panelists of 4 types of eggs (brown-shell and blue-shell eggs acquired from family farms, free-range eggs acquired from large, industrial systems, and white-shell cage eggs from industrial, cage systems.) To evaluate differences and preferences, data were analyzed in a GLM. In addition, sensory evaluation was analyzed using principal component analysis. In accordance with the survey, 99% of the participants eat eggs (P < 0.001), 58% eat 1 to 3 eggs/wk, and 84% declared to consume eggs at home (<0.0001). Surveyed participants reported that price and size are the determining factors (31%) when purchasing eggs. Among the physical characteristic for consumers, yolk color was the most important attribute rather than white color, egg appearance, texture, flavor, or odor. In the consumer acceptability test, farm eggs (either brown or blue shell) received the most favorable sensory evaluation by the panel and were preferred to both free-range and white-shell cage eggs. Yolk color was the most influential parameter in making this difference. Brown farm eggs were predominately selected for greatest general satisfaction by participants in both the sensory evaluation (P = 0.008) and in the survey (40%; P = 0.026). There were no differences between farm eggs (brown and blue shell, P > 0.05) in the evaluated parameters. There was a consequence in the information given from surveyed consumers and the sensory panel with the yolk color.

Effect of Hevea brasiliensis seed meal or Euphorbia heterophylla seed supplemented diets on performance, physicochemical and sensory properties of eggs, and egg yolk fatty acid profile in guinea fowl (Numida meleagris)

A total of 144 French selected breed (Galor) female guinea fowl (GF) of 42 wk of age were enrolled for a feeding trial of 15, 30, and 45 D duration. The birds were randomly assigned to 18 cages, each containing 8 birds. A total of 3 isonitrogenous and isocaloric dietary treatments were trialed, each diet comprising 6 replications (cages), which meant a total of 48 birds per diet. The GF were fed either a control diet C (commercial diet "FACI ponte 20", SIPRA, Ivory Coast, usually used for all poultry species) or the diet C supplemented with 5% Euphorbia heterophylla seeds (diet E) and the diet C supplemented with 5% Hevea seed meal (Hevea brasiliensis) (diet H). Animal performance were assessed for 3 periods (days 0 to 15, 0 to 30, and 0 to 45), and egg quality and composition were assessed at 15, 30, and 45 D of the trial. The results indicated no mortality during the trial. The laying rate was the highest (43.9%) with diet E and the lowest with diet C (32.5%), the laying rate with diet H being intermediate (38.5%). Diet E containing Euphorbia seeds led to a reduced cholesterol content of the eggs. Additionally, inclusion of Euphorbia seeds and, to a lesser extent, of the Hevea seed meal in the diet led to n-3 polyunsaturated fatty acid enriched GF eggs, with thereby, improved nutritional value. A sensory test did not find any difference between the 3 diets on trial.

Black Soldier Fly (Hermetia Illucens) as Dietary Source for Laying Quails: Live Performance, and Egg Physico-Chemical Quality, Sensory Profile and Storage Stability

Insects are promising candidates as alternative sustainable sources of protein for poultry species. The present research studied the effect of a dietary inclusion of a defatted black soldier fly (BSF) larvae meal as an alternative protein source in the diets of laying quails, on productive performance, egg physicochemical quality, fatty acid profile, sensory traits and storage stability. A total of 225 laying quails were divided into 3 dietary groups (5 replicates/each). A conventional soybean meal-based diet was formulated (Control group), and two other diets were formulated including either 10% (BSF10) or 15% (BSF15) defatted BSF larvae meal. Laying quails showed satisfactory productive performance throughout the trial. BSF10 and BSF15 eggs had the highest shape index (p < 0.01), shell weight and percentage (p < 0.001) and the most intense yolk color (p < 0.001). Defatted BSF larvae meal increased the eggs' saturated fatty acid content (p < 0.001) to the detriment of the polyunsaturated fraction (p < 0.001). Overall the eggs' sensory profile was not affected by the dietary treatment, but BSF15 eggs had a higher feed off-flavor vs Control group (p < 0.05). At day 28 of storage, oxidative stability was higher in BSF10 vs. Control eggs (p < 0.01). Defatted BSF larvae meal can be considered a possible alternative ingredient to soybean meal in laying quail diets, up to the 15% inclusion level.

Effect of dietary pomegranate seed oil on laying hen performance and physicochemical properties of eggs

The objective of the study was to determine the effects of pomegranate seed oil, used as a source of punicic acid (CLnA) in the diets of laying hens, on the physicochemical properties of eggs. Forty Isa Brown laying hens (26weeks old) were equally subjected to 4 dietary treatments (n=10) and fed a commercial layer diet supplying 2.5% sunflower oil (control) or three levels (0.5, 1.0 and 1.5%) of punicic acid in the diets. After 12weeks of feeding the hens, eggs collection began. Sixty eggs - randomly selected from each group - were analysed for physicochemical properties. Eggs naturally enriched with CLnA preserve their composition and conventional properties in most of the analysed parameters (including chemical composition, physical as well as organoleptic properties). Dietary CLnA had positive impact on the colour of the eggs' yolk, whereas the hardness of hard-boiled egg yolks was not affected. Additionally, increasing dietary CLnA led to an increase not only the CLnA concentrations, but also CLA in egg-yolk lipids.

Interactions between canola meal and flaxseed oil in the diets of White Lohmann hens on fatty acid profile and sensory characteristics of table eggs

The current study was designed to assess the fatty acid composition and sensory attributes of eggs procured from hens consuming diets containing canola meal (CM) and/or flax oil (FO). A total of 96 group-caged White Lohmann hens received 1 of 4 isonitrogenous and isoenergetic diets for a period of 4 weeks. Diets were arranged in a 2 × 2 factorial design, containing 24% canola meal, 7.5% flax oil, both, or neither (control). All yolk fatty acids were affected by flax oil inclusion, with the exception of stearic acid (SA) and docosapentaenoic acid (DPA). Only SA was affected by CM inclusion. Additionally, significant interactions between CM and FO were observed for linoleic acid (LA) and total omega-6 polyunsaturated fatty acids (PUFA), with DPA approaching significance (P = 0.069). Trained panelists (n = 8) evaluated 7 aroma ('egg', 'creamy', 'buttery', 'salty', 'sweet', 'barny', and 'oceanic') and 6 flavor ('egg', 'creamy', 'buttery', 'salty', 'brothy', and 'oceanic') attributes of cooked egg product. No significant differences (P > 0.05) in aroma attributes were found between eggs from different dietary treatments. However, egg, creamy, buttery, and oceanic flavors were significantly different between the dietary treatments (P < 0.05). While oceanic flavor significantly increased with inclusion of FO, egg and creamy flavors showed a significant decrease (P < 0.05). Although CM addition alone did not result in significant sensory changes, the pairing of CM and FO resulted in even greater sensory changes than using FO alone, specifically with regard to egg flavor. Results from partial least squares analyses showed a strong association between oceanic flavor and omega-3 PUFA. Oppositely, egg, creamy, and buttery flavors were more correlated with the presence of omega-6 PUFA and palmitic acid. This experiment provides evidence that the interaction between CM and FO in the White Lohmann hen diet results in sensory changes of cooked eggs associated in part with changes in yolk fatty acid content.