Super Chilling Enhances Preservation of the Freshness of Salted Egg Yolk During Long‐Term Storage

Abstract

Pasteurized egg yolk with 10% (w/w) salt was stored at 5, -5, -15, -20, and -30 degrees C for 1 to 6 mo, respectively. Changes in generation of volatiles of the stored samples (5 and -5 degrees C for 6 mo) were analyzed by SPME-GC-MS. Emulsifying properties of egg yolk stored at -5, -15, -20, and -30 degrees C for 1 mo, respectively, were also evaluated by measurement of emulsion particle diameters in model emulsions prepared with the yolk samples. In addition, structural changes in low-density lipoprotein (LDL) in the egg yolks dependent on storage conditions for 6 mo were evaluated by (31)P-NMR. Volatile compounds such as hexanal, 2-methylbutanal, and 3-methylbutanal increased in egg yolk during storage at 5 degrees C; however, volatile compounds hardly increased in any samples stored at -5 degrees C (super chilling). The mean emulsion particle diameter in super chilled egg yolk was significantly smaller than that in egg yolk stored at the other lower temperatures. In addition, the results of (31)P-NMR evaluation suggested that prevention of structural changes of LDL resulted in maintenance of emulsifying properties of egg yolk. Thus, these results indicate that super chilling is an effective means of preserving salted egg yolk during long-term storage.

Destabilization of mayonnaise induced by lipid crystallization upon freezing

“…1,2) These phenomena should be suppressed to maintain the quality of the food emulsion. Many factors associated with destabilization of O/W emulsions during freezing have been suggested: (1) Denaturation of the emulsifier and stabilizer because of low-temperature preservation, 3,4) (2) change in the amount of emulsifier absorbed or its conformation at the interface, 1,5) (3) increase in internal stress caused by volumetric expansion of water into ice, 5,6) (4) aggregation of oil droplets due to freeze concentration, 5,7) and (5) partial coalescence of oil droplets by bridge-building among fat crystals. 8,9) It has been experimentally determined that crystallization of oil is likely the main cause of the destabilization of O/ W emulsions, 1,11) and oil-rich O/W emulsions are commonly less stable toward freezing.…”

Combination of Super Chilling and High Carbon Dioxide Concentration Techniques Most Effectively to Preserve Freshness of Shell Eggs during Long‐Term Storage

“…Hexanal, which has been reported in scrambled eggs, has been identified as a product of lipid oxidation (Matiella and Hsieh 1991), and was one of the major volatile compounds in cooked yolk (Warren and others 1995). In addition, it was shown that hexanal increased in salted egg yolk stored at 5 °C (Yanagisawa and others 2009). Boyd and others (1992) suggested that hexanal was formed by the degradation of linoleic acid.…”

“…In recent research, it was reported that super chilling is an effective means for preserving salted egg yolk during long‐term storage (Yanagisawa and others 2009), indicating that super chilling (−5 °C) is more adequate than storage at other temperatures (5 °C, −15 °C, −20 °C, and −30 °C) for suppressing the generation of volatiles, structural changes in lipoprotein, and reducing the emulsifying properties of salted egg yolk. Shell eggs freeze at −5 °C during long‐term storage but do not freeze at 0 °C.…”

Effects of Sequential Combination of Moderate Pressure and Ultrasound on Subsequent Thermal Pasteurization of Liquid Whole Egg

“…The volatile compounds of LWE samples were extracted using headspace solid-phase microextraction (HS-SPME) and analyzed by gas chromatography-mass spectrometry (GC-MS), as previously reported [ 23 ], with minor modifications. In brief, a 2.0 g of LWE in a 15 mL glass vial were added 0.60 g of sodium chloride and 50 µL of the internal standard and immediately sealed with a screw cap with a silicone septum; then, the samples were equilibrated for 15 min at 45 °C followed by HS-SPME exposure at the same temperature under moderate stirring (100 rpm) for 20 min [ 28 ]. Semi-quantification was performed using cyclohexanone as the internal standard and the results were expressed in µg internal standard equivalents/100 g of whole egg, with a detection limit of 0.01 µg/100 g of whole egg.…”