Thermal resistance of Salmonella enterica serotypes, Listeria monocytogenes, and Staphylococcus aureus in high solids liquid egg mixes.

Decimal reduction times (D-values) were determined for Salmonella enterica serotypes, Listeria monocytogenes, and Staphylococcus aureus in two high solids egg mixes designated A and B (water activity [a(w)] = 0.76 and 0.82; solids = 53.12 and 52.63%; pH = 5.09 and 5.29; viscosity = 183 and 119 centipoise/s, respectively) using a low-volume (0.06 ml) sealed glass capillary tube procedure. For Salmonella, D-values ranged from 0.035 (70 degrees C) to 0.193 min (64 degrees C) in product A and from 0.048 to 0.193 min in product B. For Listeria, D-values ranged from 0.133 (70 degrees C) to 0.440 min (64 degrees C) in product A and from 0.074 to 0.364 min in product B. For Staphylococcus, D-values ranged from 0.332 (70 degrees C) to 1.304 min (64 degrees C) in product A and from 0.428 to 1.768 min in product B. For Listeria, the D-values of all heating temperatures were significantly higher (P < 0.01) in product A than in product B. The similar trend was also observed for Salmonella and Staphylococcus but only at 66 degrees C for Salmonella and 64 degrees C for Staphylococcus. Greater temperature dependence was observed for Salmonella inactivation in the low a(w) and low pH product (A), while the product (B) with the higher a(w) and pH had greater temperature dependence for Listeria. Compared across both egg mixes and all heating temperatures, the Staphylococcus strains were from 6.2 to 11.7 times more heat resistant than S. enterica serotypes and from 2.2 to 7.5 times more heat resistant than L. monocytogenes.

Thermal inactivation kinetics of Salmonella spp. within intact eggs heated using humidity-controlled air.

The heat resistance of six strains of Salmonella (including Enteritidis, Heidelberg, and Typhimurium) in liquid whole egg and shell eggs was determined. Decimal reduction times (D-values) of each of the six strains were determined in liquid whole egg heated at 56.7 degrees C within glass capillary tubes immersed in a water bath. D-values ranged from 3.05 to 4.09 min, and significant differences were observed between the strains tested (alpha = 0.05). In addition, approximately 7 log10 CFU/g of a six-strain cocktail was inoculated into the geometric center of raw shell eggs and the eggs heated at 57.2 degrees C using convection currents of humidity-controlled air. D-values of the pooled salmonellae ranged from 5.49 to 6.12 min within the center of intact shell eggs. A heating period of 70 min or more resulted in no surviving salmonellae being detected (i.e., an 8.7-log reduction per egg).

Immersion heat treatments for inactivation of Salmonella enteritidis with intact eggs.

The effects of water-bath immersion heat treatments on the inactivation of Salmonella enteritidis within intact shell eggs were evaluated. Six pooled strains of Salm. enteritidis (ca 3 x 10(8) cfu, inoculated near the centre of the yolk) were completely inactivated within 50-57.5 min at a bath temperature of 58 degrees C and within 65-75 min at 57 degrees C (an 8.4 to 8.5-D process per egg). Following the initial 24 to 35-min come-up period, semilogarithmic survivor curves obtained at 58 and 57 degrees C yielded apparent decimal reduction times (D-values) of 4.5 and 6.0 min, respectively. Haugh unit values increased during heating, while yolk index and albumen pH values were unaffected. Albumen clarity and functionality were affected by the thermal treatments; therefore, extended whip times would be required for meringue preparation using immersion-heated egg whites. Immersion-heated shell eggs could provide Salmonella-free ingredients for the preparation of a variety of minimally-cooked foods of interest to consumers and foodservice operators.

The effects of ultrapasteurization with and without homogenization on the chemical, physical, and functional properties of aseptically packaged liquid whole egg.

The effects of ultrapasteurization with and without homogenization on some chemical, physical, and functional properties of liquid whole egg were observed. Heat treatments of 64, 68, and 72 C each at 30, 60, and 95 s were conducted on liquid whole egg, unhomogenized and homogenized [10.34 mPa (1,500 psi)]. The viscosity of the egg increased with increased processing temperature, and unhomogenized egg was more viscous than homogenized egg. alpha-Amylase was inactivated at 68 C for 30 s. Although cake height was highly correlated to soluble protein content, this relationship did not hold for all time-temperature combinations. Due to homogenization effects on soluble protein results, soluble protein is not a reliable predictor of egg functionality when homogenization is used in the process. Homogenization had no effect on the population reduction of aerobic bacteria in all but three of the nine time-temperature combinations.

Effect of different protein levels fed during the prebreeder period on performance of turkey breeder hens.

An experiment was conducted to examine the effects of prebreeder protein intake on subsequent reproductive performance and to examine body weight, feed consumption, and body composition changes due to aging in Large White turkey breeder hens. One hundred twenty-nine Hybrid Large White turkey breeder hens were fed either 12, 15, or 18% CP diets (2,882 kcal ME/kg) during the prebreeder period from 24 to 32 wk of age. All hens were photostimulated with 15.5 h light/day and fed a standard 16% protein breeder ration from 32 to 55 wk of age. Prebreeder protein intake increased linearly as dietary protein increased. Treatments did not affect body weight, body composition, egg production, feed consumption, fertility, hatch of fertile eggs, or percentages of early or late dead. Body weight increased from 24 to 55 wk in a cubic response to age. Percentage of carcass moisture decreased, whereas percentage of carcass fat increased from 24 to 55 wk in a quadratic response to age. Prebreeder and breeder feed consumption were not significantly affected by treatment or age. This experiment is evidence that a 12% protein prebreeder ration is adequate for subsequent reproductive performance; observed effects of age on body characteristics agree with published data.