Quality of giant freshwater prawn (Macrobrachium rosenbergii) during the storage at −18°C as affected by different methods of freezing

Figures & data

Figure 1. Effects of different freezing methods on central temperature of giant freshwater prawn.

Figure 2. Micrographs of fresh and frozen (−18°C for 1 day) giant freshwater prawn tissues (S1: liquid nitrogen quick-freezing, S2: −35°C air-blast freezing, S3: −18°C refrigerator direct-freezing, magnification: 100×).

Figure 3. Changes in (a) thawing loss, (b) pH, (c) TVB-N, and (d) TBARS of giant freshwater prawn during the storage at −18°C.

Figure 4. Changes in K-value of giant freshwater prawn during the storage at −18°C.

Table 1. Changes in texture properties of freshwater prawn during frozen storage.

	Weeks of storage
Analyze parameters	0	4	8	12	16	20
Hardness (g)
S1	1991 ± 78^Aa	1600 ± 101^Ab	1098 ± 45^Ac	953 ± 84^Acd	885 ± 17^Acd	807 ± 62^Ad
S2	1991 ± 78^Aa	1329 ± 42^Bb	738 ± 71^Bcd	779 ± 21^ABc	724 ± 67^Bcd	673 ± 22^Bd
S3	1991 ± 78^Aa	1127 ± 111^Cb	588 ± 20^Bc	635 ± 16^Bc	553 ± 70^Cc	524 ± 28^Cc
Springiness
S1	0.98 ± 0.01^Aa	0.7 ± 0.2^Ab	0.51 ± 0.08^Abc	0.46 ± 0.04^Ac	0.48 ± 0.01^Ac	0.48 ± 0.06^Ac
S2	0.98 ± 0.01^Aa	0.59 ± 0.03^Ab	0.49 ± 0.08^Ac	0.49 ± 0.05^Ac	0.52 ± 0.04^Abc	0.49 ± 0.05^Ac
S3	0.98 ± 0.01^Aa	0.49 ± 0.05^Ab	0.47 ± 0.03^Ab	0.44 ± 0.03^Ab	0.53 ± 0.08^Ab	0.46 ± 0.05^Ab
Chewiness (g)
S1	1318 ± 52^Aa	576 ± 43^Ab	262 ± 26^Abc	158 ± 12^Ac	190 ± 10^Ac	160 ± 10^Ac
S2	1318 ± 52^Aa	459 ± 42^Ab	167 ± 14^ABc	167 ± 22^Ac	163 ± 13^Ac	139.5 ± 0.7^ABc
S3	1318 ± 52^Aa	206 ± 28^Ab	108 ± 18^Bc	102 ± 35^Ac	112 ± 15^Bc	106 ± 13^Bc
Resilience
S1	0.46 ± 0.01^Aa	0.3 ± 0.1^Ab	0.29 ± 0.01^Ab	0.22 ± 0.03^Ab	0.29 ± 0.01^Ab	0.26 ± 0.01^Ab
S2	0.46 ± 0.01^Aa	0.38 ± 0.05^Ab	0.24 ± 0.01^Bc	0.26 ± 0.01^Ac	0.28 ± 0.01^Ac	0.25 ± 0.01^ABc
S3	0.46 ± 0.01^Aa	0.26 ± 0.03^Ab	0.24 ± 0.01^Bb	0.21 ± 0.03^Ab	0.22 ± 0.02^Bb	0.23 ± 0.02^Bb

S1: Liquid nitrogen quick-freezing; S2: −35°C air-blast freezing; S3: −18°C refrigerator direct-freezing. Data are expressed as means ± standard deviation (n = 6). Means in same column with different capital letters are significantly different (P < 0.05). Means in same row with different small letters are significantly different (P < 0.05).

Table 2. Changes in color of freshwater prawn during frozen storage.

	Weeks of storage
Analyze parameters	0	4	8	12	16	20
L*
S1	57.8 ± 0.9^Aa	55 ± 3^Aab	54 ± 2^Ab	53 ± 1^Abc	52.3 ± 0.5^Abc	51.2 ± 0.4^Ac
S2	57.8 ± 0.9^Aa	53.8 ± 0.5^Ab	53.3 ± 0.2^Abc	52 ± 2^Abc	51.8 ± 0.3^Acd	50 ± 1^Ad
S3	57.8 ± 0.9^Aa	53 ± 2^Ab	53 ± 3^Abc	52.23 ± 0.08^Abc	52 ± 2^Abc	49 ± 1^Ac
a*
S1	0.25 ± 0.09^Aa	0.51 ± 0.05^Aab	1.2 ± 0.2^Aab	1.4 ± 0.2^Ab	1.6 ± 0.6^Ab	1.6 ± 0.2^Ab
S2	0.25 ± 0.09^Aa	1.0 ± 0.6^Aab	1.86 ± 0.01^Ab	1.8 ± 0.2^Bb	1.6 ± 0.3^Ab	1.8 ± 0.3^Ab
S3	0.25 ± 0.09^Aa	1.00 ± 0.08^Ab	2.1 ± 0.8^Ac	2.0 ± 0.2^Bc	2.0 ± 0.4^Ac	2.4 ± 0.2^Bc
b*
S1	9.1 ± 0.2^Aa	3.5 ± 0.2^Abcd	2.8 ± 0.8^Acd	3.9 ± 0.1^Abc	5.1 ± 0.4^Ab	1.6 ± 0.4^Ad
S2	9.1 ± 0.2^Aa	7 ± 1^Ab	4.66 ± 0.09^Abc	5.3 ± 0.1^Abc	3.3 ± 0.2^Acd	2.2 ± 0.1^Ad
S3	9.1 ± 0.2^Aa	6.2 ± 0.3^Ab	3.3 ± 0.2^Abc	5.4 ± 0.6^Ab	3.7 ± 0.8^Abc	2.0 ± 0.1^Ac
dE*
S1	35.9 ± 0.3^Aa	38 ± 2^Aab	39 ± 2^Ab	39 ± 1^Ab	39.02 ± 0.03^Ab	41.6 ± 0.5^Ac
S2	35.9 ± 0.3^Aa	39.6 ± 0.3^Ab	39.4 ± 0.5^Ab	40 ± 2^Ab	40.0 ± 0.2^Ab	42 ± 1^Ac
S3	35.9 ± 0.3^Aa	40 ± 2^Ab	41 ± 3^Ab	40.3 ± 0.1^Ab	41 ± 2^Ab	43 ± 1^Ab

S1: Liquid nitrogen quick-freezing; S2: −35°C air-blast freezing; S3: −18°C refrigerator direct-freezing. Data are expressed as means ± standard deviation (n = 6). Means in same column with different capital letters are significantly different (P < 0.05). Means in same row with different small letters are significantly different (P < 0.05).