Changes in Structural and Functional Attributes of Fish Mince Proteins in Presence of Cosolvent During Frozen Storage

Figures & data

Figure 1 Ca²⁺ ATPase activity of proteins extracted from sardine mince treated with different concentrations of mannitol during frozen storage. Ca²⁺ ATPase activity is expressed as moles of inorganic phosphate released per mg of protein per minute. A) control samples, without mannitol treatment; (B) samples treated with 2% mannitol; (C) samples treated with 4% mannitol; and, (D) samples treated with 6% mannitol.

Figure 2 SDS–PAGE pattern of proteins extracted in sample buffer from sardine mince mixed with different concentrations of mannitol and frozen stored. A) immediately after freezing; and, B) at 112 days of storage. (1) standard marker proteins; (2) mince without mannitol treatment; (3) mince treated with 2% mannitol; (4) mince treated with 4% mannitol; and, (5) mince treated with 6% mannitol. MHC–Myosin Heavy Chain, MLC-Myosin Light Chain.

Figure 3 Thermal denaturation profile of fish proteins during heating from 25 – 95°C at pH 7.5. A). The absorbance at 287 nm was monitored during heating in thermal cuvettes with a heating rate of 1°C per minute B) first derivative plot of absorbance vs temperature.

Table 1 Apparent T_m (°C) of proteins from sardine mince treated with different concentrations of mannitol during frozen storage

		With mannitol
Days of storage	Without mannitol	2%	4%	6%
0	57.0 ± 1.5	58.9 ± 1.3	58.5 ± 1.2	58.0 ± 0.9
10	57.5 ± 1.2	58.9 ± 1.1	58.3 ± 1.4	58.0 ± 1.0
20	56.7 ± 1.4	58.8 ± 1.4	57.8 ± 1.1	57.6 ± 1.2
35	56.9 ± 1.1	56.8 ± 1.0	58.0 ± 1.3	57.2 ± 1.0
49	56.8 ± 1.3	55.0 ± 1.3	58.5 ± 1.1	57.2 ± 0.9
67	57.0 ± 1.0	55.4 ± 1.2	58.6 ± 0.8	56.8 ± 1.1
77	55.8 ± 1.2	54.7 ± 1.4	56.3 ± 1.2	55.2 ± 1.3
100	55.0 ± 1.1	54.1 ± 0.7	55.8 ± 1.2	55.0 ± 1.1
Values are mean ± standard error.

Figure 4 Scanning electron micrographs of sardine mince during frozen storage in presence of mannitol. A) control samples, without mannitol treatment immediately after freezing; B) at 120 days of storage; C) sardine mince treated with 6% mannitol immediately after freezing; and, D) at 120 days of storage.

Table 2 Emulsion capacity of proteins from sardine mince treated with different concentrations of mannitol during frozen storage. Emulsion capacity expressed as ml oil/ mg protein

		With mannitol
Days of storage	Without mannitol	2%	4%	6%
0	0.13 ± 0.02	0.12 ± 0.01	0.12 ± 0.01	0.14 ± 0.02
14	0.13 ± 0.02	0.12 ± 0.01	0.12 ± 0.01	0.14 ± 0.02
30	0.14 ± 0.02	0.12 ± 0.02	0.14 ± 0.02	0.14 ± 0.01
42	0.12 ± 0.01	0.11 ± 0.01	0.15 ± 0.01	0.14 ± 0.02
51	0.12 ± 0.01	0.12 ± 0.02	0.12 ± 0.01	0.12 ± 0.01
75	0.13 ± 0.01	0.11 ± 0.01	0.12 ± 0.01	0.12 ± 0.02
100	0.13 ± 0.01	0.12 ± 0.01	0.13 ± 0.01	0.10 ± 0.01
Values are mean ± standard error.

Figure 5 Water absorption capacity of sardine mince during frozen storage in presence of mannitol. Water absorption capacity is expressed as g of water absorbed per gram of freeze dried mince. A) control; B) 2% mannitol; C) 4% mannitol; and, D) 6% mannitol.