Whole Egg Research Articles

Effects of egg powder on the structure of highland barley dough and the quality of highland barley bread

The influences of egg white (EW), egg yolk (EY) and whole egg (WE) on the structure of highland barley dough and the quality of highland barley bread were explored. The results showed that egg powder reduced G' and G" of highland barley dough, which led to the softer texture of dough and endowed bread with a larger specific volume. EW increased the percentage of β-sheet of highland barley dough, EY and WE promoted the transformation from random coil to β-sheet and α-helix. Meanwhile, more disulfide bonds were formed from free sulfhydryl groups in the doughs with EY and WE. These properties of highland barley dough could help highland barley bread develop a preferable appearance and textural feature. It is worth noting that highland barley bread containing EY has more flavorful substances and a better crumb structure, which were similar to that of whole wheat bread. The highland barley bread with EY received a high score according to the sensory evaluation in consumer acceptance.

Prolonged Egg Supplement Advances Growing Child's Growth and Gut Microbiota.

Protein-energy malnutrition still impacts children's growth and development. We investigated the prolonged effects of egg supplementation on growth and microbiota in primary school children. For this study, 8-14-year-old students (51.5% F) in six rural schools in Thailand were randomly assigned into three groups: (1) whole egg (WE), consuming 10 additional eggs/week (n = 238) (n = 238); (2) protein substitute (PS), consuming yolk-free egg substitutes equivalent to 10 eggs/week (n = 200); and (3) control group (C, (n = 197)). The outcomes were measured at week 0, 14, and 35. At the baseline, 17% of the students were underweight, 18% were stunted, and 13% were wasted. At week 35, compared to the C group the weight and height difference increased significantly in the WE group (3.6 ± 23.5 kg, p < 0.001; 5.1 ± 23.2 cm, p < 0.001). No significant differences in weight or height were observed between the PS and C groups. Significant decreases in atherogenic lipoproteins were observed in the WE, but not in PS group. HDL-cholesterol tended to increase in the WE group (0.02 ± 0.59 mmol/L, ns). The bacterial diversity was similar among the groups. The relative abundance of Bifidobacterium increased by 1.28-fold in the WE group compared to the baseline and differential abundance analysis which indicated that Lachnospira increased and Varibaculum decreased significantly. In conclusion, prolonged whole egg supplementation is an effective intervention to improve growth, nutritional biomarkers, and gut microbiota with unaltered adverse effects on blood lipoproteins.

Whole Eggs Improve High-Fat Diet-Induced Disorders of the Hepatic Lipid Profile and Gut Microbiota in Mice

The relationship between egg consumption and disturbances of hepatic lipid metabolism remains controversial. Recent studies indicate that egg consumption showed favorable effects on dyslipidemia, while underlying mechanisms remain largely undefined. In this study, the high-fat diet was fed to C57BL/6J mice to induce lipid metabolism disorders, aiming to disclose the effects of the whole eggs (WEs) and yolk-free egg substitute (YFES) on the hepatic lipid profile and gut microbiota. The daily WE/YFES dose for mice was 7.55 mg/g of mouse weight. The results showed that WE inhibited body weight gain and significantly decreased hepatic triglyceride (TG) by 49.6% while showing insignificant effects on the total cholesterol in the liver. Both WE and YFES alleviated hepatic oxidative stress by decreasing hepatic levels of malondialdehyde. Lipidomic analysis revealed that diacylglycerol, lysophosphatidylcholines, ceramide, and free fatty acids were the major lipid species upregulated by WE. Moreover, WE showed beneficial effects on gut microbiota by increasing the abundance of Bacteroidota while decreasing Proteobacteria levels. The correlation analysis showed that Lactobacillales and Bacteroides displayed a significant negative correlation with hepatic TG and free fatty acids (18:4), while positively correlated with phosphatidylethanolamine biomarkers. These results evidenced that WE was more effective than YFES in improving hepatic lipid profiles and regulating the gut microbiota, resulting in increased levels of probiotics and inhibited TG accumulation and oxidative stress through the gut–liver axis. Therefore, it could be concluded that the consumption of WE instead of YFES would be helpful in relieving hepatic dyslipidemia in the short term.

Functional enhancement of whey protein concentrate and egg by partial denaturation and co-processing

This study investigated functional enhancement strategies for whole egg (WE), egg yolk (EY) and whey protein concentrate (WPC) with a view to reducing their required concentrations in formulations and the resulting environmental footprint. WE and EY underwent a combined phospholipase PLA2 and controlled heat treatment (WE2 and EY2) while WPC was partially-denatured via controlled heating (pdWPC). WE2 and EY2 samples were mixed with pdWPC and were also control-heated (h) with WPC. WE2-WPC(h) foams proved more stable than their untreated controls. WE2, EY2 and EY2-pdWPC showed higher emulsifying properties than their untreated controls. pdWPC, EY2 and EY2-WPC(h) hydrogels proved more viscoelastic than their untreated controls. EY2 and EY2-WPC(h) displayed an additional 45 kDa protein band, which could correspond to surface-active apoproteins released from lipoproteins. This work highlighted the potential to enhance WE, EY and WPC functionality via combined partial denaturation treatments and via synergy between WPC and WE or EY when co-processed.

Long Term Whole Egg, but Not Egg White Supplementation Promotes Growth and Bifidobacteria and Lachnospira Without Increasing LDL-Cholesterol in Primary School Children

ObjectivesWe aimed to determine long-term effects of egg supplementation on growth, blood lipoproteins, blood proteins, nutritional status, and microbiota in primary school children.MethodsA randomized controlled, cluster study was performed at 6 rural schools in Central, Eastern, and Western Thailand. 635 students (8–14 years old) were recruited into the study. Subjects were randomly assigned into 3 groups, based on weight for age: 1) Whole eggs (WE) - consume 10 additional eggs per week [n = 238] 2) Egg substitute (ES) - consume yolk-free egg substitute equivalent to 10 eggs per week [n = 200], and 3) control group (C, [n = 197]). The anthropometric, biochemical indexes, dietary intake, and microbiota were measured at week 0 (baseline), week 13–14, and week 34–35.ResultsAt baseline, 14% were under-weighed, 9% were stunted, and 16% were wasted. At 34–35 weeks, the increases in body weight and height were higher in WE group than those in C group (3.56 ± 0.93 kg, P < 0.001 and 5.11 ± 0.92 cm, P < 0.001). No significant differences in weight and height were observed between the ES and C groups. Prealbumin levels were higher (1.53 ± 0.33 mg/dL, P < 0.001) in WE but not ES as compared with C. There were significant decreases in total cholesterol, triglycerides, and LDL cholesterol in WE but not ES as compared with C. Additionally, HDL cholesterol tended to increase in WE (0.66 ± 0.99 mg/dL, ns) as compared with C. Bacterial diversity in WE, ES and C group was not significantly change neither alpha nor beta diversity. After whole egg supplementation, the overall relative abundance of the Bifidobacterium was increased up to 1.28-fold. The differential abundance analysis also indicated that Lachnospira significantly increased and Varibaculum significantly decreased after whole egg supplementation.ConclusionsLong-term whole egg supplementation significantly enhanced growth in young children with no adverse effect on blood cholesterol levels. The result coincided with promoting health-benefit gut bacteria. However, further insight into the mechanistic effect of egg consumption on gut microbiota and growth is needed.Funding SourcesAgricultural Research Development Agency (ARDA), Thailand.

Spray-Drying Hen Eggs: Effects of the Egg Yolk to Egg White Ratio and Sucrose Addition on the Physicochemical, Functional, and Nutritional Properties of Dried Products and on Their Amino Acid Profiles

Manufactured egg powders can be formulated to produce food products that vary in their properties. The present study aims to determine the effect of egg white content on the physicochemical characteristics and on the functionality and nutritional value of dried whole egg (WE), egg white (W), and an egg yolk/white mixture in a 1:3 ratio (M1:3). These fresh egg products were spray-dried using sucrose—an agent recognized for its effect of protecting the protein in the egg during the drying process. Experiments were conducted in a laboratory-scale spray dryer, operated under controlled conditions, with an air inlet temperature of 120 °C. In the dried products, water activity, water solubility index, color, and pH were affected significantly as a function of the fresh egg component ratio and the added sucrose. The wettability and dispersibility in water of egg powder were improved when sucrose was added to the WE. The water-holding capacity was highest in dried egg white, and higher in the M1:3 mixture without sucrose added than in the WE with 5% sucrose. The results suggest that modifying the ratio of fresh egg yolk to egg white could lend some control over the protein and fat contents of dried egg products and over their functional properties.

Lipidomic Profiling Reveals the Effect of Egg Components on Nonalcoholic Steatosis in HepG2 Cells and Its Involved Mechanisms

AbstractNon‐alcoholic fatty liver disease (NAFLD) is a major cause of cardiovascular disease. The relationship between egg consumption and NAFLD is still controversial for its high cholesterol content. In this study, the effects of different egg components (egg white (EW), egg yolk (EY), and whole egg (WE)) on NAFLD are examined using oleic acid (OA)‐induced HepG2 cells with UPLC‐ESI‐MS/MS approach. The results show EY could affect the lipid profile effectively by increasing phosphocholine (PC), phosphatidylglycerol (PG), and carnitine (CAR). Orthogonal projections to latent structures−discriminate analysis (OPLS‐DA) combine with S‐plot analysis select 10, 82, and 20 potential biomarkers in EW, EY, and WE group, respectively. Up‐regulated TG, DG, and down‐regulated lysophosphatidylcholines (lysoPC), lysophosphatidylethanolamine (lysoPE) biomarkers are found in EY group, while down‐regulated TG and FFA are found in EW and WE group. Glycerolipid and choline metabolism are the most involved pathways affected by EY and WE. In addition, the mechanism is associated with the expression of Pla2g15, Pnpla6‐1, Gad1, and involved lipogenic genes ABC1 and PPARα. This study suggests that WE treatment can ameliorate OA‐induced hepatic steatosis by inhibiting TG accumulation, while EY seems slightly accelerate hepatic steatosis. Furthermore, the effects are closely associated with its effects on glycerolipid metabolism.Practical applications: Nonalcoholic fatty liver disease (NAFLD) is a worldwide disease, while the associations between egg consumption and NAFLD are still poorly understood. This study investigates the effects of egg components on NAFLD in oleic acid (OA)‐induced HepG2 cells based on a targeted lipidomics approach. The results indicate that WE (whole egg) treatment could ameliorate OA‐induced hepatic steatosis by inhibiting TG and FFA accumulation, which is closely associated with glycerolipid metabolism. The results provide knowledge and understanding of the effects of egg on NAFLD and involved mechanism, and further provided nutritional guidelines for egg consumption.

Skeletal Muscle Regulatory Markers Responses Following Whole And Egg White Ingestion In Resistance Trained Men

Protein ingestion is recommended to maximize muscular adaptations post resistance training (RT). Eggs are a rich food source commonly consumed post-workout to meet protein requirements. Although removing egg yolk is often promoted for the improvement of body composition (BC), whole-egg (WE) consumption has been shown to cause a greater stimulation of post-exercise muscle protein synthesis than egg-white (EW). However, changes in BC and skeletal muscle regulatory markers to chronic RT coupled with WE or EW consumption have not been evaluated. PURPOSE: To compare the effects of WE vs. EW ingestion after 12 wks of RT on BC and skeletal muscle regulatory markers in RT men. METHODS: Thirty RT men [age (24 ± 2 yrs), were randomized to either a WE (n=15) or EW (n=15) consumption group for 12 wks. The WE group ingested three WE while the EW group ingested six EW immediately post-workout and at the same time on non-training days. RT consisted of 10 exercises/session, 3x wk. Three sets of 3-14 reps (load was progressed) were performed for each exercise. Body weight, fat mass (FM), skeletal muscle mass (SMM) as well as serum follistatin (FOL), myostatin (MYO) and basic fibroblast growth factor (FGF-2) levels were measured at baseline and after 12 wks. RESULTS: Significant main effects of time were observed for body weight, SMM, FOL and FGF-2 which significantly (P < 0.05) increased, and for FM and MYO which significantly (P < 0.05) decreased. However, no significant group × time interactions were noted for any markers. Although non-significant, the WE group had ~1 Kg of extra FM loss than EW group. CONCLUSIONS: There are no differences in the changes achieved in BC and skeletal muscle regulatory factors after 12 wks of RT between WE and EW consumption. Although BC did not differ between groups, the ~1 Kg of extra FM loss seen after WE consumption may be an advantage for fitness enthusiasts with aesthetic goals.

Whole Egg Consumption Decreases Cumulative Weight Gain in Diet-Induced Obese Rats

Whole egg (WE) consumption has been demonstrated to attenuate body weight (BW) gain and adiposity in genetic animal models of type 2 diabetes (T2D). This finding was accompanied by increased food consumption. This study aimed to examine the effects of long-term WE intake on BW gain, fat distribution, and food intake in a rat model of diet-induced obesity (DIO). Male Sprague Dawley rats (n=24) were obtained at 5 wk of age and were randomly weight-matched across 1 of 4 dietary intervention groups (6 rats per group): a casein-based diet (CAS), a high-fat high-sucrose CAS diet (HFHS CAS), a whole egg-based diet (EGG), or a high-fat high-sucrose EGG diet (HFHS EGG). All diets provided 20% (w/w) protein and were provided for 33 wk. HFHS diets provided ∼61% of kilocalories from fat and 10% from sucrose. Daily weight gain and food intake were recorded, biochemical parameters were measured via ELISA, and epididymal fat pad weights were recorded at the end of the study. At 33 wk, cumulative BW gain in DIO rats fed HFHS EGG resulted in 23% lower weight gain compared with DIO rats fed HFHS CAS (P <0.0001), but no significant differences in BW gain were observed between the HFHS EGG group and the control EGG and CAS groups (P=0.71 and P=0.61, respectively). Relative food intake (grams per kilogram BW) was 23% lower (P<0.0001) in rats fed HFHS CAS compared with CAS, whereas there was no difference in food intake within the EGG dietary groups. DIO rats fed HFHS EGG exhibited a 22% decrease in epididymal fat weight compared with their counterparts fed the HFHS CAS. Our data demonstrate that consumption of a WE-based diet reduced BW gain and visceral fat in the DIO rat, similar to our previous findings in a genetic rat model with T2D.

Improved rheological properties of chicken egg frozen gels fortified by ᴅ-ketohexoses

The aim of this study was to examine the rheological properties of chicken egg gels containing 10% ᴅ-ketohexose (ᴅ-fructose, ᴅ-allulose, ᴅ-tagatose, and ᴅ-sorbose) and to compare the effects of ketohexoses on freeze-thawing of egg gels with ᴅ-glucose (Glc), sucrose (Suc), and trehalose (Tre). In both whole egg (WE) and egg white (EW) gels, ketohexose-gels had higher breaking stress than Glc-, Suc-, and Tre-gel (WE gels, 15.6–35.3%; EW gels, 7.6–26.1%). The ketohexose-gels of WE showed similar viscoelastic properties and water-holding capacity to Glc-, Suc-, and Tre-gel. Ketohexose-gels of EW possessed higher viscosity and higher water-holding capacity than the other sugar-gels. Ketohexoses more effectively suppressed the syneresis and physical properties of egg gels by freeze-thawing than Glc, Suc, and Tre did. The application of ketohexoses to egg gel products can improve the quality of frozen foods that contain egg gels. Practical applications Sugar is extensively used for producing egg-based gel products because sugar contributes to the stabilization of food structure and adds sweetness. Sugar also prevents deterioration of the physical properties of frozen foods from freezing and thawing. Interest in the rare ketohexoses ᴅ-allulose (Alu) and ᴅ-tagatose (Tag) is growing in food industry, because Alu and Tag have some health benefits, such as prevention of postprandial blood glucose level and suppression of adiposity. The utilization of rare ketohexoses as food ingredients should improve the rheological and functional properties of food products, including those of frozen foods.

Biofilm formation by Salmonella Enteritidis in a simulated liquid egg processing environment and its sensitivity to chlorine and hot water treatment

This study investigated the biofilm formation by three S. Enteritidis strains in a simulated liquid egg processing environment using 0.1% peptone water (PW) (control), 10% whole eggs (WE), 10% egg yolks (EY) and 10% egg whites (EW) as growth media, and evaluated the effectiveness of chlorine (200 ppm, 5 min) and hot water (71 °C, 30 s) treatments against S. Enteritidis biofilms. The results showed that S. Enteritidis formed significantly (P < 0.05) denser biofilms in PW and EW compared to those in WE and EY. However, biofilms formed in PW were less resistant to chlorine treatment than those formed in WE, EY, and EW, with average log reductions of 6.34, 2.28, 0.67 and 0.95 CFU/cm2, respectively. Microscopic observation showed that biofilm morphology was greatly affected by the growth medium, and the egg matrices might act as protective barriers, contributing to the greater chlorine resistance. All biofilms were very sensitive to hot water treatment, which reduced the cell populations by 4.30–7.08 log CFU/cm2. This study could advance our understanding towards the biofilm forming abilities of S. Enteritidis in liquid egg processing environments and the effectiveness of sanitation methods against S. Enteritidis biofilms, which may aid in the development of better sanitation strategies.

Low-Allergenic Hydrolyzed Egg Induces Oral Tolerance in Mice

Background: Egg allergy is one of the most common food allergies in children. The standard therapy for egg allergy is strict avoidance. Yet, there is considerable clinical and scientific interest in primary or secondary prevention. A major drawback of oral tolerance (OT) induction protocols, however, is the possibility of severe side effects; thus, we have formulated a hypoallergenic egg product and demonstrate its in vivo capacity to modulate the immune system in the current study. Methods: Hydrolyzed egg (HE) was produced using a combination of moderate heat treatment and enzymatic hydrolysis. The capacity of HE to induce OT was tested in experimental models and compared to whole egg (WE). Delayed-type hypersensitivity (DTH) responses, immune markers and potential early markers of OT were analyzed. Results: Allergic responses, assessed by both DTH responses upon OVA challenge and serum OVA-specific IgE and IgG1, were decreased after treatment with HE and WE compared to the control group. Additionally, feeding WE and HE significantly decreased Th2 cytokine induction and cell proliferation, induced the activation of effector CD4+ T cells and increased numbers and percentages of ICOS+CD4+CD25+Foxp3+ cells. Furthermore, DO11.10 mouse experiments showed that HE contains other peptides than the OVA_323-339 peptide that are able to induce tolerance to OVA. Conclusions: Altogether, results showed that HE induces OT in mice in a dose-dependent manner. Due to its low allergenicity compared to WE, it may represent a safer alternative for OT induction in at-risk subjects or oral immunotherapy in allergic patients.

Sensory and physico-chemical characteristics of desserts prepared with egg products processed by freeze and spray drying

In this work, three freeze-dried (FD) egg products (whole egg (WE), egg yolk (EY) and egg white (EW)) were obtained and the acceptability of confections prepared with each was evaluated. Sensory analyses for confections were performed by hedonic testing with fifty panelists in each evaluation. The studied confections were: Condensed Milk Pudding (P), Quindim (Q) and Meringue (M). The results obtained for confections made with FD egg products were compared with the achieved through other formulations of the same desserts made with fresh (F) or spray-dried (SD) egg products. The sensory analysis results for confections made with FD egg products showed good acceptance by panelists. A principal component analysis of the sensory evaluation data was carried out to identify similarities between the different egg products. The PCA supported the conclusion that FD egg products can substitute their fresh and SD counterparts in dessert formulations with good acceptability while keeping the advantages conferred by the freeze-drying method.

Physical properties of egg whites and whole eggs relevant to microwave pasteurization

Microwave pasteurization is a novel thermal processing technology in which non-uniform heating may be a major challenge. In this study, the suitability of using egg whites (EWs) and whole eggs (WEs) as model foods to evaluate the heating uniformity and to determine the cold and hot spots during microwave pasteurization was investigated. The samples were prepared from mixtures of water with commercial EW or WE powders at different solid concentrations (20%, 25%, 27.5%, and 30%) and salt contents (0, 50, 100, and 200mM). Critical physical properties for desirable model food systems include appropriate dielectric properties, gelation temperatures, gel strengths, and water holding capacities (WHCs). The gelation temperature of liquid EW and WE were 70 and 80°C; both fell in the pasteurization temperature range. At 915MHz, the dielectric constants of liquid EW and WE samples and their heat induced gels decreased with solid concentration while the loss factor was not affected. Loss factors of liquid EW and WE samples increased linearly with salt addition, which could be explained by the linear increase of electrical conductivities by adding salt. The strength and WHC of heat induced EW and WE gels increased linearly with solid concentration, while salt addition had no significant effect. The results demonstrated the suitability of using EW and WE as model foods to determine the heating uniformity during microwave pasteurization process.

PLASMA SUÍNO E OVO INTEIRO EM RAÇÕES DE LEITÕES SOBRE O DESEMPENHO NA FASE INICIAL E INCIDÊNCIA DE DIARRÉIA

Sixty-four piglets were used to evaluate the use of skim milk (SM) feed, three increasing levels of swine plasma (SP) feed, three increasing levels of whole egg (WE) feed and a high inclusion of soybean meal (SB) trial feed. Swine plasma and WE replaced, respectively, 25%, 50% and 75% and 15%, 30% and 45% of crude protein from skim milk in SM feed. During the experimental period, piglet´s performance and diarrhea incidence were evaluated from 21 to 34 days of age. The use of WE replacing 45% of crude protein of SM, for piglets, presented similar performance results to SM, showing that WE is a potential protein feed for piglets. The use of high level of soybean meal feed caused the worst performance results of piglets in the first post-weaning week, from 21 to 34 days of age, confirming the need of limiting the inclusion of soybean meal to post-weaning feed. The use of different levels of SP and WE and high level of SB in trial feed did not affect diarrhea incidence in piglets.KEYWORDS: piglets; protein sources; skim milk; soybean meal; weight gain.

Plasma suíno e ovo inteiro em rações de leitões sobre desempenho na fase inicial e efeito residual até a terminação

Foram utilizados 64 leitões distribuídos em oito tratamentos: ração com leite em pó (LP), três rações com níveis crescentes de plasma suíno (PS), três rações com níveis crescentes de ovo inteiro (OI) e ração com alto nível de farelo de soja (FS). Avaliou-se o ganho diário de peso (GDP), o consumo diário de ração (CDR) e a conversão alimentar (CA). Os animais que consumiram ração FS apresentaram média de GDP superior aos demais tratamentos, dos 35 aos 48 dias de idade. O aumento dos níveis de PS proporcionou redução linear do GDP, dos 21 aos 35 e dos 35 aos 48 dias de idade e do CDR dos 48 aos 138 dias de idade e piora linear da CA, dos 21 aos 35 dias de idade. Considerando o período da desmama até à terminação as rações inicias podem conter PS e OI, substituindo parcialmente à PB do leite em pó em 25 e 45%, respectivamente.

Diferentes fontes proteicas em rações de leitões sobre atividade da tripsina e parâmetros sangüíneos

Foram utilizados 64 leitões, submetidos a oito tratamentos: ração com leite em pó (LP), três rações com níveis crescentes de plasma suíno (PS), três rações com níveis crescentes de ovo inteiro (OI) e ração com alto nível de farelo de soja (FS). Foi coletado sangue dos animais aos 27 e 34 dias de idade para avaliação dos parâmetros sangüíneos, e aos 28 e 35 dias de idade quatro animais por tratamento foram abatidos para coleta do pâncreas e posterior determinação do peso absoluto (PA) e peso relativo (PR) do pâncreas e da atividade da tripsina (AT). Os tratamentos não influenciaram significativamente o PA e a AT. Verificou-se efeito significativo dos níveis crescentes de PS, com redução linear dos leucócitos e aumento do volume globular, aos 27 dias; enquanto aos 34 dias, observou-se aumento linear das hemácias. Aos 27 dias, os animais arraçoados com níveis de PS apresentaram menor percentagem de eosinófilos do que aqueles arraçoados com níveis de OI. A utilização de plasma suíno promoveu menor estímulo à resposta imune, enquanto que a utilização de ovo inteiro promoveu maior resposta humoral dos leitões.

The survivability of Bacillus anthracis (Sterne strain) in processed liquid eggs

In this study, we investigated the survival and inactivation kinetics of a surrogate strain of Bacillus anthracis (Sterne strain) in whole egg (WE), egg white (EW), sugared egg yolk (YSU), and salted egg yolk (YSA) at low (−20, 0, and 5 °C), moderate (15, 20, 25, 30, 35, and 40 °C), and high storage temperatures (45, 50, 55, and 60 °C). Outgrowth of the spores was measured as lag phase duration (LPD). Replication of vegetative cells was measured in terms of growth rate (GR) and maximum population density (MPD). Spore inactivation was recorded as inactivation rate and percent reduction in viable count. In general, spore viability decreased at low and high temperatures and increased at moderate temperatures. At 0 and 5 °C, a 60–100% reduction in spore viability was seen within 2–3 weeks in WE and YSU, 0–30% in YSA, and 50–100% in EW. At −20 °C, however, no drop in spore titer was observed in YSU and EW but a 20% drop in titer was seen in YSA and 50% in WE within 2–3 weeks. At high temperatures, WE, EW, and YSA produced a 20–50% drop in the spore titer within 1–4 h whereas YSU showed 100% inactivation within 0.75 h. At moderate storage temperatures, as the temperature increased from 15 to 40 °C, LPD decreased from 13.5 to 0.75 h and MPD reached 0.27–2.2 × 10 9 CFU/ml in YSU and WE, respectively. Markedly lower growth was observed in YSA (LPD = 24–270 h, MPD = 9 × 10 5 CFU/ml) and spores were inactivated completely within 1–6 h in EW. The survivability and inactivation data of B. anthracis in liquid egg products reported in this investigation will be helpful in developing risk assessment models on food biosecurity.

The nutritive value of egg by-products and their potential bactericidal activity:in vitro andin vivo studies

Technical-grade egg albumen (TA) and whole egg (WE) by-products are produced in substantial quantities by egg-breaking facilities across North America. TA and WE products are recovered during processing but are not approved for human consumption. Both products are known to be rich in fat, maternal antibodies, protein and lysozyme, a bactericidal enzyme. The objective of this research was to explore the potential for egg by-products to be used as a valuable protein, energy and bactericidal supplement in animal nutrition. To improve the nutritive value of TA and WE, spray-dried samples were heat treated at various temperatures and their digestible protein content was determined in vitro using a pepsin/pancreatin digestion/dialysis system. In addition, enhancement of lysozyme activity towards Gram-negative bacteria (GNB) by heat or irradiation was examined. Optimal protein digestibility for TA averaged 80% following heat treatment at 105–110 °C for 10 min. In contrast, protein digestibility of spray-dried TA was only 55%. Heat treatment (100–122 °C) of spray-dried WE or hot room storage of spray-dried TA and WE products at 70 °C for up to 14 days had a minimal effect on protein digestibility in vitro. Heat treatment or γ-irradiation of lysozyme for at least 20 min at 80 °C or 0.5 kGy, respectively, increased antimicrobial activity towards GNB. When compared with either the heat or radiation control treatments, reductions in Escherichia coli and Salmonella enterica serovar Typhimurium populations increased by at least 1 and 0.5 log10, respectively. In contrast, the effect of irradiation (2 kGy) on the antimicrobial activity of spray-dried TA was less pronounced. In a feeding trial, rats fed spray-dried TA and spray-dried TA subjected to either radiation (1.8 kGy) or heat (80 °C, 20 min) treatment exhibited a body weight gain and protein utilisation equal to or higher than the control (casein diet). In contrast, feeding spray-dried WE or TA and WE previously maintained in a hot room (70 °C) for 3 days had a negative effect on rat growth and protein utilisation. In the case of WE products this was substantiated by poor digestibility of essential amino acids, including lysine, threonine and, to some extent, methionine. When compared with the control treatments, inclusion of heat-treated or irradiated TA in the rat diets reduced the population of Enterobacteriaceae. Copyright © 2006 Society of Chemical Industry

Sensitivity of multidrug-resistant Salmonella typhimurium DT104 to organic acids and thermal inactivation in liquid egg products

A mixture of four Salmonella typhimurium DT104 strains and a mixture of four S. typhimurium non-DT104 strains were examined for their ability to grow in tryptic soy broth (TSB) acidified with acetic, lactic, citric, or malic acids at pH 5·4, 4·4, and 3·7. Significantly (P<0·05) higher numbers of S. typhimurium DT104 cells were detected at pH 4·4 and 4·0 in TSB acidified with acetic acid and at pH 4·4 and 3·7 in TSB acidified with lactic acid compared to non-DT104 cells. Acid-shocked and non-shocked (control) cells were plated on TSA (pH 7·3) acidified with lactic acid at pH 5·4, 4·4, and 4·0 and on TSA (pH 7·0±0·2) containing 0·5, 2·5, and 5% sodium chloride. Populations of acid-shockedS. typhimurium DT104 and non DT104 cells recovered on acidified or salt-supplemented TSA were significantly (P<0·05) lower than those of non-shocked cells. A significantly lower number of acid-shocked non-DT104 cells recovered on TSA at pH 5·4, compared to acid-shocked DT104 cells, suggests that DT104 cells may be more resistant to acid shock and subsequent exposure to acid pH. D values and z values of acid-shocked or non-shocked cells of DT104 and non-DT104 strains in liquid whole egg (WE), egg yolk (EY), egg white (EW), whole egg+10% salt (WES), and egg yolk+10% salt (EYS) were determined. Differences in thermal sensitivity of the two types of cells were few. Rates of thermal inactivation of S. typhimurium DT104 cells indicate that the USDA pasteurization process would eliminate >8 log10cfu ml−1of EW heated at 57°C and >11 log10cfu ml−1of WE, EY, WES, or EYS heated at 61°C. D values of acid-shocked DT104 and non-DT104 cells heated in liquid egg products were significantly (P<0·05) lower than those of respective non-shocked cells.