Table 2. Changes of TBARS, iron content and color during multiple freeze-thaw cycles

Freeze-thaw cycles	Fat content	TBARS (mg/kg)	Iron content		Color parameters
Freeze-thaw cycles	Fat content	TBARS (mg/kg)	Heme iron content (mg/kg)	Non-heme iron content (mg/kg)	L*	a*	b*
C₀	F₀	0.19±0.01^Aa	9.90±0.17^Aa	10.98±0.49^Aa	49.39±0.84^Ba	–0.91±0.02^Aa	7.73±0.23^Ba
	F₅₀	0.19±0.03^Aa	9.12±0.08^Ba	11.47±0.40^Aa	50.58±0.46^ABa	–0.73±0.07^ABa	7.18±0.23^Ba
	F₁₀₀	0.22±0.02^Aa	8.82±0.05^Ba	12.03±0.59^Aa	51.32±0.05^ABa	–0.64±0.04^Ba	6.93±0.08^ABa
	F₁₅₀	0.33±0.01^Ba	8.69±0.13^Ba	12.38±0.49^Aa	52.26±0.35^Aa	–0.59±0.01^Ba	6.29±0.24^Aa
C₁	F₀	0.38±0.01^Aa	8.64±0.17^Ab	11.05±0.20^Aa	48.84±0.26^Ca	–0.86±0.04^Aa	8.00±0.02^Ca
	F₅₀	0.41±0.02^ABb	8.09±0.23^Ab	11.89±0.40^ABa	50.23±0.18^Ba	–0.29±0.08^Bb	7.88±0.01^Cab
	F₁₀₀	0.47±0.03^BCb	7.31±0.04^Bb	12.45±0.20^BCa	51.03±0.11^ABa	–0.11±0.02^BCb	7.59±0.11^Bb
	F₁₅₀	0.50±0.00^Cb	7.05±0.08^Bb	13.15±0.00^Cab	52.28±0.53^Aa	0.09±0.03^Cb	7.18±0.07^Aab
C₂	F₀	0.77±0.04^Ab	7.41±0.42^Ac	12.52±0.30^Aab	47.53±0.61^Cab	–0.63±0.03^Ab	8.80±0.18^Ba
	F₅₀	0.84±0.03^Ac	7.04±0.07^ABc	12.59±0.20^Aa	48.88±0.32^BCb	0.06±0.04^Bc	8.11±0.17^Aab
	F₁₀₀	0.80±0.05^Ac	6.82±0.03^ABb	13.08±0.10^ABab	49.88±0.33^ABab	0.10±0.01^Bc	8.48±0.12^ABc
	F₁₅₀	0.84±0.03^Ac	6.27±0.13^Bb	13.71±0.20^Bb	51.22±0.45^Aab	0.17±0.02^Bb	8.07±0.08^Ab
C₃	F₀	0.94±0.02^Ab	5.54±0.28^Ad	13.71±0.40^ABc	45.98±0.14^Cb	–0.28±0.01^Ac	10.44±0.45^Ab
	F₅₀	1.06±0.02^Bd	4.39±0.17^Bd	14.20±0.30^ABb	47.48±0.55^BCc	0.29±0.08^Bcd	9.46±0.62^Ab
	F₁₀₀	1.11±0.01^BCd	3.90±0.05^BCc	14.30±0.25^ABbc	49.32±0.59^ABb	0.50±0.06^Bd	9.01±0.04^Ad
	F₁₅₀	1.16±0.03^Cd	3.04±0.27^Cc	15.17±0.30^BCd	50.13±0.81^Ab	0.83±0.06^Ce	9.29±0.35^Ac
C₄	F₀	1.34±0.11^Ac	3.34±0.15^Ae	14.55±0.59^Acd	43.47±0.64^Bc	0.21±0.04^Ad	11.89±0.18^Bc
	F₅₀	1.37±0.01^Ae	3.05±0.17^ABe	14.76±0.49^Ab	44.85±0.23^ABd	0.48±0.06^Ade	11.36±0.73^ABc
	F₁₀₀	1.48±0.05^Ae	2.98±0.42^Abd	14.97±0.20^Acd	45.54±0.37^Ac	0.54±0.07^Ade	9.83±0.22^Ae
	F₁₅₀	1.49±0.01^Ae	2.06±0.34^Bd	14.97±0.40^Ac	46.10±0.18^Ac	0.60±0.01^Ac	9.61±0.38^Ac
C₅	F₀	1.79±0.05^Ad	2.24±0.37^Af	14.69±0.79^Acd	42.48±0.57^Cc	0.50±0.05^Ae	13.47±0.57^Ad
	F₅₀	1.92±0.05^ABf	1.89±0.13^Af	15.17±0.30^ABc	43.94±0.22^BCd	0.57±0.02^ABe	12.54±0.63^Acd
	F₁₀₀	1.92±0.01^ABf	1.84±0.09^Ae	15.87±0.49^Ade	45.53±0.62^ABc	0.63±0.05^Bef	11.96±0.09^Af
	F₁₅₀	2.03±0.06^Bf	1.41±0.22^Ad	16.22±0.00^Ad	46.56±0.46^Ac	0.61±0.01^ABc	11.93±0.08^Ad
C₆	F₀	2.48±0.10^Ae	0.86±0.07^Ag	16.08±0.00^Ad	41.32±0.63^Bc	0.58±0.02^Ae	14.00±0.02^Bd
	F₅₀	2.67±0.03^ABg	0.55±0.02^Bg	16.36±0.20^Ac	42.03±0.07^ABe	0.62±0.01^Ae	13.61±0.37^Bd
	F₁₀₀	2.78±0.03^Bg	0.48±0.08^Bf	16.85±0.30^ABe	42.61±0.37^ABd	0.75±0.02^Bf	13.12±0.16^ABg
	F₁₅₀	2.87±0.04^Bg	0.10±0.07^Ce	17.34±0.20^Be	43.46±0.58^Ad	0.72±0.01^Bd	12.51±0.23^Ad

Means within pork back fat content with different superscript letters are significantly different (p <0.05).
Means within with freeze-thaw cycles different superscript letters are significantly different (p <0.05).
C₀, fresh surimi before freezing; C₁–C₆, the number of freeze-thaw cycles; F₀, F₅₀, F₁₀₀, and F₁₅₀ are surimi of 0 g/kg fat, 50 g/kg fat, 100 g/kg fat and 150 g/kg fat, respectively; TBARS, thiobarbituric acid reactive substances.