2.3.4 Foaming properties
The foaming properties were determined according to Stone et al.(2015). In brief, a 1.0% (w/w) protein solution (corrected by protein
content) was prepared at pH 3, 5, and 7 and stirred overnight at 4℃. For
each protein solution, 15 mL (V li) was
transferred into a 400 mL tall glass beaker (inner diameter = 69 mm;
height = 127 mm; as measured with a digital caliper) and foamed using an
Omni Macro homogenizer (Omni International, Marietta, GA, USA) with a 20
mm saw tooth generating probe for a total of 5 min at speed 4
(~7,200 rpm). The foam was immediately transferred to a
50- or 100-mL graduated cylinder (inner diameter = 26 mm) after
homogenization. The foam volume was recorded at time zero
(V fi) and after 30 min
(V ft) at room temperature. The foaming capacity
(FC) and foaming stability (FS) were determined using following the
equations:
\(\%FC=\frac{V_{\text{fi}}}{V_{\text{li}}}\times 100\%\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (3)\)
\(\%FS=\frac{V_{\text{ft}}}{V_{\text{fi}}}\times 100\%\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (4)\)
where Vfi is the volume of foam immediately after
homogenization, and Vft is the volume of foam remaining
after 30 min.
2.3.5 Statistical analysis
All protein products were prepared in triplicate on separate fermented
meals (n=3). The results were reported as mean ± one standard deviation.
A two-way analysis of variance (ANOVA) was used to study the statistical
differences in protein functionality using a Tukey’s test with a
significance level of p <0.05. A simple Pearson
correlation (r ) was used to describe the relationship between the
functional properties. The statistical analysis was performed using the
IBM SPSS Version 28.0 software (IBM Corp. NY, IL, USA).