Physico-Chemical and Functional Properties of Proteins from Pelagic Fatty Fish (Sardinella longiceps) as a Function of Water Washing

Figures & data

Table 1 Proximate composition of fresh unwashed and washed oil sardine meat based on wet weight basis (kg/100 kg mince)

Properties	Unwashed	Once washed	Thrice washed	Five times washed
Moisture	66.29 (0.32)	73.96 (0.85)	77.81 (1.29)	78.27 (0.65)
Protein	17.39 (0.43)	16.60 (0.64)	15.14 (0.53)	14.12 (0.64)
Fat	14.44 (0.29)	9.15 (0.38)	4.23 (0.22)	2.31 (0.43)
Ash	2.32 (0.06)	1.31 (0.04)	0.70 (0.04)	0.40 (0.02)

Values in parenthesis are SD with n = 3.

Figure 1. Effect of number of water washing cycles of fresh sardine meat on A—nonprotein nitrogen constituents; B—pH of meat.

Table 2 Properties of proteins from fresh unwashed and washed oil sardine meat

Properties	Unwashed	Once washed	Thrice washed	Five times washed
Reduced viscosity at 3 mg/mL protein concentration (dl/g)	0.90	1.24	1.01	1.70
Water absorption capacity (g water/g dried material)	2.16 (0.06)	2.99 (0.01)	3.23 (0.04)	3.54 (0.03)
Fat absorption capacity (g oil/g dried material)	2.49 (0.07)	2.88 (0.02)	4.19 (0.16)	3.01 (0.03)
Emulsion capacity (mL oil/mg protein)	0.28 (0.01)	0.29 (0.01)	0.30 (0.005)	0.30 (0.05)
Gel strength (N. M)	0.019 (0.0004)	0.024 (0.0007)	0.032 (0.0002)	0.035 (0.0005)
Expressible water (%)	35.05 (0.30)	32.11 (0.58)	23.77 (0.67)	22.53 (1.30)

Values in parenthesis are SD, n = 3.

Figure 2. Gel filtration profile of total proteins from unwashed and washed fresh oil sardine meat in extraction buffer (PB 50 mM, pH 7.5, containing 1.0 M NaCl. A—unwashed meat; B—once washed meat; C—thrice washed meat; D—five times washed meat.

Figure 3. SDS-PAGE pattern of total proteins from unwashed and washed oil sardine meat. Lane s—standard markers; a—unwashed meat; b—once washed meat; c—thrice washed meat; d—five times washed meat.

Table 3 Correlation coefficient (r) between number of washings and different parameters analyzed

Parameters compared	r value
Washing vs. Fat	−0.9521a
Washing vs. NPN	−0.8286a
Washing vs. WAC	0.9052a
Washing vs. FAC	0.4552a
Washing vs. EC	0.9028a
Washing vs. GS	0.9781a
Washing vs. EW	−0.9568a

^a p < 0.05, n = 3.

Figure 4. Dynamic visco-elastic behavior of fresh unwashed and washed oil sardine meat in the temperature range of 30–90°C. A—unwashed meat; B—once washed meat; C—thrice washed meat; D—five times washed meat.