Antibacterial Properties of TMA against Escherichia coli and Effect of Temperature and Storage Duration on TMA Content, Lysozyme Activity and Content in Eggs

Studies on trimethylamine (TMA) in egg yolk have focused on how it impacts the flavor of eggs, but there has been little focus on its other functions. We designed an in vitro antibacterial test of TMA according to TMA concentrations that covered the TMA contents typically found in egg yolk. The change in TMA content in yolk was analyzed at different storage temperatures and for different storage durations. The known antibacterial components of eggs, including the cuticle quality of the eggshell and the lysozyme activity and content in egg white, were also assessed. The total bacterial count (TBC) of different parts of eggs were detected. The results showed that the inhibitory effect of TMA on Escherichia coli (E. coli) growth increased with increasing TMA concentration, and the yolk TMA content significantly increased with storage duration (p < 0.05). The cuticle quality and lysozyme content and activity significantly decreased with storage time and increasing temperature, accompanied by a significant increase in the TBC on the eggshell surface and in the egg white (p < 0.05). This work reveals a new role for trace TMA in yolks because it reduces the risk of bacterial colonization, especially when the antibacterial function of eggs is gradually weakened during storage.

Changes in microbial, physiochemical, and functional properties of pasteurized liquid whole egg during refrigerated storage

BACKGROUND

Liquid eggs have the advantages of high hygiene security, easy use, and convenient transportation, but their shelf life is only limited to 2~3 weeks. The microbial, physiochemical, and functional properties of pasteurized LWE were investigated in this study to evaluate the quality of pasteurized liquid whole egg (LWE) during refrigerated storage.

RESULTS

The tested shelf life of the pasteurized LWE was 16 days when stored at 4 °C. During refrigerated storage, Pseudomonas gradually became the dominant bacterium in LWE following lactic acid bacteria, although the initial number of Pseudomonas after pasteurization was relatively limited (< 10 CFU mL^-1 ). A total of 23 strains, including six Pseudomonas strains, were obtained. The pH of pasteurized LWE decreased with the growth of microorganisms, while the content of total volatile basic nitrogen (TVB-N) increased curvilinearly. The average particle size increased almost continuously until the sample reached its shelf life. The functional properties of pasteurized LWE were also reduced after a week of refrigerated storage at 4 °C when the microorganisms in pasteurized LWE entered an exponential growth period and the TVB-N content of pasteurized LWE reached its first peak.

CONCLUSION

During refrigerated storage, Pseudomonas was the dominant bacterium in LWE next to lactic acid bacteria. After a week of refrigerated storage at 4 °C, the particle size of LWE increased, while the functional properties of LWE reduced. This study provides a basis for extending the shelf life of liquid egg products in future research. © 2020 Society of Chemical Industry.

Effect of preservatives on the shelf-life and sensory characteristics of pasteurized liquid whole egg stored at 4°C

The study focused on the effects of traditional (benzoate-sorbate and triphosphates) and alternative (nisin, Laktocid, Defence JB, and Galimax Flavor) food preservatives on the microbiological quality and sensory properties of pasteurized liquid whole eggs (LWE). The LWE samples with the addition of a test preservative and a control were stored at 4°C for 45 D. The selected microbiological parameters, sensory attributes, and color space parameters were determined. The results were statistically analyzed by means of factorial ANOVA, followed by the Tukey post hoc test. The multivariate method of principal component analysis based on the correlation matrix was employed to assess the relationships between pH and sensory characteristics of LWE. Total plate counts at the end of storage differed significantly, being the lowest in samples with benzoate-sorbate (1.69 ± 0.12 log cfu.g-1) and Laktocid (2.12 ± 0.12 log cfu.g-1). The final counts of lactic acid bacteria on day 45 were lower in the samples with benzoate-sorbate, triphosphates, nisin, and Laktocid (maximum 1.01 ± 1.44 log cfu.g-1). The amounts of yeasts at the end of storage did not differ among samples with different preservatives; none were detected in any samples with the exception of Defence JB (1.28 ± 1.90 log cfu.g-1). The lowest final mold count was observed in LWE with Laktocid (0.92 ± 1.29 log cfu.g-1). In conclusion, Laktocid showed great potential as a preservative; it had however a negative impact on pH value and the sensory properties of LWE.

Rice protein coating in extending the shelf-life of conventional eggs

The effectiveness of rice protein coatings or mineral oil on maintaining interior quality and eggshell breaking strength of fresh eggs was evaluated during storage at 20°C for 8 wk. Egg quality was assessed by weight loss, Haugh unit (HU), albumen pH, yolk index (YI), shell strength, and scanning electron microscopy in uncoated eggs (control treatment) and eggs coated with mineral oil or rice protein concentrate at 5, 10, or 15%. The HU and YI were higher in coated eggs (P < 0.001). Weight loss increased (P < 0.001) during long-term storage. Uncoated eggs showed the highest weight loss (8.28%), whereas mineral oil (0.87%) and rice protein at 5% (5.60%), 10% (5.45%), 15% (5.54%) solutions were effective in preventing weight lost (P < 0.001). The use of the coatings preserved the internal quality of the eggs for up to 4 wk longer than uncoated eggs (HU, YI, and pH). Uncoated eggs had the worst (P < 0.001) HU (54.45), albumen pH (9.18), and YI (0.28) after 8 wk of storage. Among the coated eggs, the mineral oil had the best values of HU (70.54), pH (8.48), and YI (0.35) after storage. The eggs coated with 5, 10, and 15% of rice protein presented results with similar intern quality between them and intermediary quality in relation to the others treatments during all the storage period. Scanning electron microscopy demonstrated a lower surface porosity in coated eggshell, indicating that the use of the coating may provide a protective barrier against the transfer of gases and moisture. In conclusion, the use of coatings based on rice protein concentrate or mineral oil influences the internal quality of eggs during storage and may be an effective alternative for increasing the shelf-life of commercial eggs.

A review on biogenic amines in food and feed: toxicological aspects, impact on health and control measures

Biogenic amines (BAs) represent a considerable toxicological risk in some food and feed products. They are formed under unhygienic conditions during storage and processing; therefore, an increase in the concentrations of those metabolites is related to putrefaction. Because BAs are thermostable, they remain in food and feed that have undergone heat treatment. There are several toxicological effects, especially caused by histamine, when high concentrations of BAs are ingested by humans, depending on the food itself and also on individual susceptibility and individual health status. The present paper reviews the main BAs in meat products, their use as spoilage indicators, the risk on human health and also the contamination of by-product meals. Furthermore, we highlight the state of art regarding impact of BAs on poultry, meat and eggs.

Avaliação da qualidade interna de ovos de consumo pela pesquisa do teor de aminas bioativas

Com o objetivo de avaliar a qualidade dos ovos de consumo pela pesquisa dos níveis de aminas bioativas, foram coletados, pelos serviços de inspeção oficiais, 224 amostras de ovos provenientes de cinco regiões distintas do estado de Minas Gerais, durante o período de um ano. As aminas biogênicas (putrescina, cadaverina, feniletilamina, histamina e tiramina) e as poliaminas (espermidina e espermina) foram pesquisadas por cromatografia líquida de alta eficiência e detecção ultravioleta (CLAE/UV) após derivação pré-coluna com cloreto de dansila. Os resultados demonstraram que a putrescina estava presente, em baixas concentrações, em todas as amostras de gema e de albúmen. As demais aminas também foram detectadas, porém em menor frequência, e a espermina somente foi encontrada em uma amostra de albúmen. Foi concluído que os ovos de consumo produzidos no estado de Minas Gerais não são uma fonte considerável de poliaminas, importantes para o crescimento e a proliferação celular, e os baixos teores de aminas biogênicas, formadas pela descarboxilação de aminoácidos por enzimas bacterianas, não representam riscos à saúde do consumidor, o que indica que o ovo apresenta boa qualidade, tomando por base o critério de aminas bioativas.

Aminas bioativas e qualidade da carne de frangos de corte

Com o objetivo de avaliar a qualidade da carne de frangos de corte mediante pesquisa dos níveis de aminas bioativas, foram coletadas, pelos serviços de inspeção oficiais, 160 amostras de carcaças provenientes de cinco regiões distintas do estado de Minas Gerais, durante o período de um ano. As poliaminas (espermidina e espermina) e as aminas biogênicas (putrescina, cadaverina, histamina, tiramina) foram pesquisadas por cromatografia líquida de alta eficiência e detecção ultravioleta (CLAE/UV). Os resultados encontrados demonstraram a presença das poliaminas, espermidina e espermina, em todas as amostras, em concentrações médias de 3,56mg/100g e 5,72mg/100g, respectivamente. Em todas as amostras foram detectadas, em concentrações muito baixas, as aminas putrescina, cadaverina, histamina e tiramina. Foi concluído que a carne de frangos de corte produzida no estado de Minas Gerais é uma fonte de poliaminas, importantes para o crescimento e a proliferação celular, e que os baixos teores de aminas biogênicas encontrados não representam riscos à saúde do consumidor, indicando que esse tipo de carne apresenta boa qualidade, tomando por base o critério de aminas bioativas.

Effects of packaging, mineral oil coating, and storage time on biogenic amine levels and internal quality of eggs

This study was carried out with the aim of evaluating the effects of mineral oil application on eggshells and the use of plastic packages with lids on the physical-chemical and microbiological quality and biogenic amine contents of eggs stored under refrigeration for up to 125 d. A total of 1,920 eggs from 46-wk-old Hyline W36 laying hens were randomly distributed into 4 groups soon after classification: (i) 480 eggs were stored in pulp carton tray packages; (ii) 480 eggs were stored in plastic packages with lids; (iii) 480 eggs were stored in carton packages after the application of mineral oil; and (iv) 480 eggs were stored in plastic packages with lids after the application of mineral oil. The internal quality was measured by Haugh units, by the counts of mesophilic and psychrotrophic microorganisms, by the most probable number of total and thermal-tolerant coliforms, by the counts of molds and yeasts, by the analysis of Salmonella spp. and Staphylococcus spp., and by the levels of biogenic amines in the egg yolk and albumen. The application of mineral oil to the eggshell resulted in higher Haugh unit values throughout storage, and the use of plastic packages altered the internal quality. The application of mineral oil and the use of packaging had no effects on the microbiological and biogenic amine results. Microbiological analyses showed the absence of Salmonella spp., Staphylococcus aureus, thermal-tolerant coliforms, and fungi. However, the highest counts of mesophilic (1.1 × 10(7) cfu/g) and psychrotrophic (6.7 × 10(7) cfu/g) microorganisms were recorded. The highest values of biogenic amines detected and quantified were putrescine (2.38 mg/kg) and cadaverine (7.27 mg/kg) in the egg yolk and putrescine (1.95 mg/kg), cadaverine (2.83 mg/kg), and phenylethylamine (2.57 mg/kg) in the albumen. Despite these results, the biogenic amine levels recorded were considered low and would not be harmful to consumer health.