EFFECT OF PHOSPHOLIPASE A₁ON THE PHYSICOCHEMICAL AND FUNCTIONAL PROPERTIES OF HEN'S EGG YOLK, PLASMA AND GRANULES

Abstract

Fresh egg yolk was separated into plasma and granules. Then, the egg yolk and its fractions were enzymatically modified with phospholipase A1 (PLA1). Changes in physicochemical and functional properties were investigated. We observed that enzymatic treatment showed a significant impact on the properties of egg yolk and its fractions with regard to emulsifying properties, protein solubility and foaming properties. Meanwhile, the color changes and the microstructure and the thermal behavior of egg yolk, plasma and granules before and after enzymatic treatment were also studied. This study indicated that the existence of lysophospholipids and structural changes in egg yolk granules could be responsible for significant differences in the functional properties of untreated and PLA1‐modified egg yolk, plasma and granules. PRACTICAL APPLICATIONS This study aimed to investigate the physicochemical and functional properties of egg yolk, including its fractions (plasma and granules), before and after phospholipase A1 (PLA1) treatment. Such modified egg yolk would have higher protein solubility, thermal stability and emulsifying properties, and present high resistance to extreme temperatures. As these properties of egg yolk powder were improved through PLA1 treatment, the application of PLA1 could make egg yolk have a good practical effect and extend the scope of application.

Comparative Study on Foaming Properties of Egg White with Yolk Fractions and Their Hydrolysates

“…These results indicated that both lipase and phospholipase A 2 may effectively act on the complex structures in yolk (both plasma and granules). However, partially aggregated particles were visible, which might have been caused by the heat treatments during hydrolysis [ 33 , 34 ]. As can be observed, there are many roughened pores and pitted surfaces that appeared in LEG, which indicates that LP acted on the inside of yolk granules instead of acting on the surface.…”

Effects of degree of hydrolysis (DH) on the functional properties of egg yolk hydrolysate with alcalase

“…Strixner et al (2013) reported that solubility and surface activity of egg yolk granules was significantly improved by modification with phospholipase A 2 after spray drying compared to nonmodified particles. Jin et al (2013) pointed that phospholipase A 1 modification has a markedly impact on properties of egg yolk and its fractions with regard to protein solubility, emulsifying properties, and foaming properties. However, there is little information on the effect of controlled enzymatic hydrolysis of the whole egg yolk on their functional properties and surface hydrophobicity.…”

Lipases and Their Functionality in the Production of Wheat‐Based Food Systems

“…Probably, the formed monoacyl lipids complexed with amylose and, just as in starch model systems (Van Steertegem and others ), delayed pasting and, as such cake structure setting. An alternative explanation may reside in the altered protein behavior upon addition of lipases (Daimer and Kulozik ; Jin and others ; Mine ) because egg protein coagulation and denaturation also contribute to cake structure setting. Mine () reported enhanced heat stability of ovalbumin when coupled to LPC, and suggested the formation of a structurally heat‐stable complex of lysophospholipids and polypeptides in low‐density lipoproteins.…”

“…Daimer and Kulozik (), for pure egg yolk, also observed an increased heat stability of its proteins despite their higher solubility upon treatment with phospholipase A2 (see above). Recently, Jin and others () stated that both formation of lysophospholipids and changes in egg yolk granule structure (disintegration) can be responsible for increased thermal stability. The improved crumb structure can probably be explained similarly as in bread making by invoking improved gas cell stabilization (see above), whereas the improved softness follows from the increased volume (Guy and Sahi ).…”