Effects of ball milling treatment on physicochemical properties and digestibility of Pacific oyster (Crassostrea gigas) protein powder

Abstract

The oyster protein was ball milling treated in this work, and the effects on particle size, conformation, physicochemical properties, and in vitro protein digestibility (IVPD) were investigated. After ball milling treatment, the particle size obviously decreased, and the protein powder became denser and more homogeneous. The ball milling treatment could not change the primary structure of oyster protein. However, it could affect the secondary structure and physicochemical properties. The disulfide bond increased from 8.18 to 9.14 μmol/g protein, while the protein surface hydrophobicity index increased from 0.088 to 0.176. The decreasing water-holding capacity from 390% to 226% and the increasing oil-binding capacity from 91.2% to 189.1% were related to the alterations of conformation and physicochemical properties. Ball milling could also improve the IVPD from 54.6% to 82.4%. These results provided theoretical basis for the application of ball milling treatment in the utilization of oyster protein in the food industry.

Keywords: Crassostrea gigas; ball milling; in vitro digestibility; physicochemical properties.

Figure 1

SEM for ball‐milled oyster protein (500 ×  magnification). (a) 0 min, (b) 4 min, (c) 8 min, (d) 12 min, (e) 16 min, (f) 20 min

Figure 2

Particle size distribution of ball‐milled oyster protein

Figure 3

SDS‐PAGE of ball‐milled oyster protein. M: molecular weight markers

Figure 4

Changes of the content of disulfide bond (a) and surface hydrophobicity index (b) of ball‐milled oyster protein

Figure 5

Effects of ball milling on water‐holding capacity and oil‐binding capacity of oyster protein

Figure 6

Effect of ball milling on in vitro protein digestibility