Physicochemical, microbiological, and sensory attributes of chitosan-coated grass carp (Ctenopharyngodon idellus) fillets stored at 4°C

Figures & data

Table 1. Sensory evaluation criterion of grass carp fillets.

Quality parameter	Description	Score
Color	Glossy appearance, bright surface	5
	Slight glossy appearance, bright surface	4
	Slight glossy appearance, dull surface	3
	No glossy appearance, a little yellow surface	2
	No glossy appearance, yellow surface	1
Odor	No fishiness, no earthy smell	5
	Little fishiness, no off-odor	4
	Little freshness and off-odor	3
	Distinct freshness and off-odors	2
	Strong freshness and off-odors	1
Overall acceptance	Fresh, totally acceptable	5
	Little fresh, acceptable	4
	Little fresh, reluctant acceptance	3
	Not fresh, unacceptable	2
	Not fresh, totally unacceptable	1

Figure 1. Changes in a: water loss, b: pH and c: TBA of grass carp fillets during refrigerated storage. Vertical bars represent the standard deviations (n=3).

Figure 2. Changes in a: TVB-N value and b: TMA-N value of grass carp fillets during refrigerated storage. Vertical bars represent the standard deviations (n=3).

Figure 3. Changes in K value of grass carp fillets during refrigerated storage. Vertical bars represent the standard deviations (n=3).

Table 2. Change in texture properties of grass carp fillets during refrigerated storage.

	Days of storage
Analyse parameters	0	1	3	7	11	15	20
Hardness (g)
Control	10666.42 ± 544.60^aA	6402.81 ± 1352.19^aB	5479.88 ± 548.49^aB	3591.21 ± 744.61^aC	3506.21 ± 544.04^aC	3038.31 ± 909.08^aC	2283.38 ± 468.67^aC
CH1%	10369.32 ± 609.71^aA	6304.80 ± 693.12^aB	5194.64 ± 609.31^aC	3557.97 ± 913.41^aD	3567.79 ± 353.22^aD	3538.83 ± 728.14^bD	2867.80 ± 631.58^bD
CH2%	10777.89 ± 895.84^aA	6544.36 ± 407.02^aB	5718.16 ± 671.27^aC	4128.41 ± 707.52^bD	4222.97 ± 308.07^bDE	3534.53 ± 799.70^bDE	2999.05 ± 323.30^bE
Springiness
Control	0.848 ± 0.040^aA	0.755 ± 0.138^aAB	0.746 ± 0.132^aAB	0.735 ± 0.144^aAB	0.761 ± 0.102^aAB	0.734 ± 0.081^aAB	0.615 ± 0.082^aB
CH1%	0.888 ± 0.041^aA	0.760 ± 0.077^aB	0.747 ± 0.100^aB	0.706 ± 0.080^aB	0.671 ± 0.066^aB	0.708 ± 0.077^aB	0.678 ± 0.086^aB
CH2%	0.893 ± 0.072^aA	0.806 ± 0.086^aAB	0.786 ± 0.095^aAB	0.754 ± 0.101^aB	0.766 ± 0.079^aAB	0.723 ± 0.085^aB	0.700 ± 0.127^aB
Cohesiveness
Control	0.394 ± 0.018^aA	0.334 ± 0.050^aB	0.274 ± 0.008^aC	0.248 ± 0.030^aCD	0.258 ± 0.039^aCD	0.221 ± 0.023^aDE	0.209 ± 0.024^aE
CH1%	0.396 ± 0.017^aA	0.348 ± 0.032^aB	0.329 ± 0.042^abBC	0.282 ± 0.032^aDE	0.299 ± 0.019^bCD	0.253 ± 0.019^aE	0.242 ± 0.046^bE
CH2%	0.405 ± 0.021^aA	0.354 ± 0.024^aABC	0.347 ± 0.072^bAB	0.293 ± 0.129^aBCD	0.266 ± 0.034^aBCD	0.254 ± 0.023^aCD	0.237 ± 0.041^aD
Gumminess
Control	2867.53 ± 350.60^aA	1958.12 ± 389.51^aB	1491.14 ± 122.28^aC	1012.82 ± 376.75^aD	870.82 ± 208.40^aDE	730.96 ± 265.09^aDE	552.21 ± 187.19^aE
CH1%	2502.11 ± 484.96^aA	1971.06 ± 342.20^aB	1848.25 ± 317.60^bB	1084 ± 186.28^aC	1011.30 ± 304.79^bAC	832.46 ± 205.06^aAC	663.62 ± 234.04^aA
CH2%	2573.41 ± 647.01^aA	2120.32 ± 470.36a^AB	1668.95 ± 245.31^abBC	1253.96 ± 331.42^aCD	930.37 ± 247.81^aD	1012.26 ± 341.77^bD	831.53 ± 229.26^bD
Chewiness
Control	2269.80 ± 331.47^aA	1615.88 ± 510.04^aB	1171.83 ± 236.90^aC	743.30 ± 199.29^aD	663.98 ± 81.59^aD	555.05 ± 244.69^aD	404.01 ± 183.66^aD
CH1%	2119.50 ± 352.42^aA	1531.88 ± 314.97^aB	1259.44 ± 211.01^aB	745.62 ± 172.95^aC	792.83 ± 156.51^aC	819.73 ± 224.95^bC	607.77 ± 117.51^bC
CH2%	2182.77 ± 525.45^aA	1701.34 ± 384.29^aB	1214.35 ± 175.78^aC	858.44 ± 175.78^aCD	739.27 ± 114.83^aD	849.97 ± 340.61^bCD	592.47 ± 174.78^bD
Resilience
Control	0.218 ± 0.024^aA	0.151 ± 0.037^aB	0.103 ± 0.012^aC	0.076 ± 0.011^aD	0.065 ± 0.010^aD	0.060 ± 0.009^aD	0.062 ± 0.010^aD
CH1%	0.200 ± 0.020^aA	0.146 ± 0.035^aB	0.131 ± 0.037^aB	0.093 ± 0.025^aC	0.065 ± 0.024^aC	0.077 ± 0.006^bC	0.066 ± 0.010^aC
CH2%	0.210 ± 0.020^aA	0.146 ± 0.029^aB	0.133 ± 0.053^aB	0.091 ± 0.041^aC	0.064 ± 0.006^aC	0.072 ± 0.013^abC	0.063 ± 0.013^aC

Values are expressed as means ± SD (n = 6).

Means in same column with different small letters are significantly different (p < 0.05).

Means in same row with different capital letters are significantly different (p < 0.05).

Figure 4. Changes in a: total viable count (TVC) and b: psychrotrophic count (PTC) values of grass carp fillets during refrigerated storage. Vertical bars represent the standard deviations (n=3).

Table 3. Changes in sensory evaluation of grass carp fillets during refrigerated storage.

		Storage time (days)
Sensory attributes	Treatment	0	3	7	11	15	20
Odor	Control	5.00 ± 0.01^aA	3.77 ± 0.31^aB	3.33 ± 0.25^aC	2.83 ± 0.35^aD	2.53 ± 0.15^aDE	2.13 ± 0.06^aE
	CH1%	4.50 ± 0.10^bA	3.93 ± 0.21^abB	3.53 ± 0.06^aBC	3.30 ± 0.44^abC	3.00 ± 0.50^abCD	2.57 ± 0.32^bD
	CH2%	4.50 ± 0.00^bA	4.40 ± 0.17^bA	3.97 ± 0.21^bB	3.93 ± 0.21^bB	3.60 ± 0.36^bBC	3.43 ± 0.12^cC
Color	Control	5.00 ± 0.00^aA	4.17 ± 0.29^aB	4.00 ± 0.20^aB	3.20 ± 0.26^aC	2.40 ± 0.10^aD	2.23 ± 0.12^aD
	CH1%	4.30 ± 0.15^bA	4.27 ± 0.21^aA	4.03 ± 0.21^aAB	3.33 ± 0.58^abBC	3.00 ± 0.62^abC	2.83 ± 0.25^bC
	CH2%	4.50 ± 0.10^bA	4.5 ± 0.06^aA	4.33 ± 0.15^aA	4.13 ± 0.35^bAB	3.63 ± 0.32^bBC	3.57 ± 0.40^cC
Overall acceptance	Control	5.00 ± 0.00^aA	4.13 ± 0.21^aB	3.50 ± 0.20^aC	2.70 ± 0.36^aD	2.07 ± 0.25^aE	1.90 ± 0.26^aE
	CH1%	4.80 ± 0.10^abA	4.63 ± 0.32^bA	4.10 ± 0.10^bB	3.40 ± 0.17^bC	2.80 ± 0.20^bD	2.63 ± 0.40^bD
	CH2%	4.63 ± 0.15^bA	4.66 ± 0.15^bA	4.27 ± 0.25^bAB	4.03 ± 0.06^cB	3.47 ± 0.25^cC	2.83 ± 0.38^bD

Values are expressed as means ± SD (n = 3).

Means in same column with different small letters are significantly different (p < 0.05).

Means in same row with different capital letters are significantly different (p < 0.05).