Shelf life extension of liquid whole eggs by heat and bacteriocin treatment

Abstract

During a 15-month period, samples of commercially pasteurised liquid whole egg (LWE) were tested for the presence of spoilage microflora. The total bacterial counts were 2.2 ± 0.6 log CFU/g and total lactic acid bacteria (LAB) counts were 1.9 ± 0.6 log CFU/g. Enterobacteriaceae were detected in 2 samples. Out of the tested samples, 45 LAB were isolated and identified, with 30 strains identified as Enterococcus faecium, 12 as Enterococcus faecalis, and 3 as Lactobacillus paracasei subsp. paracasei. All strains, except 6 strains of E. faecium, possessed lipolytic activity. All the E. faecalis strains and one strain of E. faecium showed a high proteolytic activity, while moderate proteolytic activity was shown by 3 lactobacilli strains. Minimum inhibitory concentration (MIC) of nisin and Micocin X was measured against groups of isolated strains, and ranged from 10.4 µg/ml to 41.7 µg/ml for nisin and from 0.2 mg/ml to 1.6 mg/ml for Micocin X. The LWEs supplemented with 6.25 mg/l of nisin or with 500 mg/ml of Micocin X were pasteurised at 65°C for 2.5 minutes. The shelf life of LWE with the addition of nisin or Micocin X stored under refrigerator conditions was extended by a minimum of 5 weeks.

Microbial Quality of Industrial Liquid Egg White: Assumptions on Spoiling Issues in Egg‐Based Chilled Desserts

“…However, the 4 Enterococcus faecalis isolates were highly proteolytic. Although performed under different conditions regarding the type (liquid or dried milk, casein) and concentration of the substrates, the type of culture (liquid or solid), and the type of detection of the activity (spectrophotometry for liquid cultures), the data presented in the present study confirmed those of Veljovic and others (), Miller and others (), and Moreno and others (). These authors have reported that the level of the proteolytic activity depended on the strain inside a same genus.…”

“…Finally, the remaining of enterococci concerned 93% of the contaminated pasteurized liquid egg white samples analyzed, corroborating the observations of Protais and others (), Hidalgo and others (), and Miller and others () in whole egg products. Enterococci are widely distributed in the environment, principally inhabiting the human and animal gastrointestinal tract (Moreno and others for review).…”

“…However, the pasteurization of whole egg products is possible under stronger conditions than those used for egg white, due to the higher heat‐resistance of egg yolk proteins. The resulting level of contamination reported in the literature is nearly similar as that found in pasteurized liquid egg white, that is, around 2.3 log CFU/mL of mesophilic aerobic bacteria for pasteurized whole egg products processed in France (Protais and others ) and also in Canada (Miller and others ).…”

“…On the few studies reporting the contamination of pasteurized liquid egg products by heat resistant bacteria, Enterococcus sp. (Hidalgo and others ; Miller and others ) and bacteria of the Bacillus cereus group (Baron and others ; Techer and others ) were already highlighted in pasteurized liquid whole egg products. However, little is known on the microbial quality of industrial egg white.…”

Scientific Opinion on the public health risks of table eggs due to deterioration and development of pathogens

“…The surviving bacteria are gram-positive cells of the genera Streptococcus, Enterococcus and, as expected, the sporeforming Bacillus. With the exception of (Miller et al, 2010), who discussed the expression of proteolytic and lipolytic activities by Enterococcus spp. Strains isolated from whole egg products, the involvement of bacterial enzymatic activities in the spoilage of egg products has not received sufficient attention for establishing a clear relationship between a type of bacterium and a specific characteristic of spoilage.…”