Microbial communities and biogenic amines of crucian carp (Carassius auratus) fillets during partial freezing and chilled storage

Figures & data

Figure 1. Changes in sensory scores (A) and TVC (B) of crucian carp fillets stored at T1 (4°C) and T2 (−3°C) (TVC: total viable counts).

Table 1. Changes in biogenic amines content of crucian carp fillets stored at 4°C (CS) and −3°C (PFS).

Storage time (days)		Biogenic amines(mg/kg)
		TRM	2-PHE	PUT	CAD	HIM	TYM	SPD	SPM
CS	0	3.12 ± 0.17^a	3.95 ± 0.04^a	5.12 ± 0.01^a	0.19 ± 0.00^a	6.02 ± 0.08^a	20.4 ± 0.05^a	5.87 ± 0.46^a	4.68 ± 0.00^a
	2	3.15 ± 0.25^a	3.96 ± 0.00^a	5.15 ± 0.09^a	0.57 ± 0.01^a	5.72 ± 0.13^a	13.74 ± 0.38^b	5.87 ± 0.00^a	6.14 ± 0.00^a
	4	3.41 ± 0.17^a	6.40 ± 0.43^b	5.15 ± 0.03^a	0.26 ± 0.00^a	6.33 ± 0.77^a	27.66 ± 0.92^c	6.07 ± 0.41^a	9.51 ± 0.01^a
	6	2.6 ± 0.26^b	4.01 ± 0.20^a	5.12 ± 0.02^b	0.55 ± 0.07^b	6.16 ± 0.78^b	18.29 ± 2.04^d	5.73 ± 0.42^b	10.48 ± 0.59^b
	8	3.17 ± 0.15^a	4.73 ± 0.42^c	5.21 ± 0.12^a	0.19 ± 0.01^a	6.78 ± 0.12^a	22.78 ± 0.70^e	5.52 ± 0.33^a	10.95 ± 0.28^a
	10	5.59 ± 0.10^c	4.33 ± 0.49^ac	6.84 ± 0.24^c	0.50 ± 0.10^c	6.53 ± 0.44^c	20.26 ± 0.41^a	5.02 ± 1.20^c	12.26 ± 0.69^c
	12	8.08 ± 0.56^d	4.31 ± 0.00^ac	7.68 ± 0.00^d	0.84 ± 0.00^d	8.65 ± 0.23^d	41.86 ± 1.42^f	6.22 ± 0.39^d	12.26 ± 0.70^d
PFS	0	3.14 ± 0.15^ac	3.95 ± 0.04^a	5.12 ± 0.01^ac	0.19 ± 0.00^a	6.02 ± 0.08^a	22.55 ± 3.72^ab	5.87 ± 0.46^a	8.49 ± 1.05^ac
	5	2.95 ± 0.22^ac	5.68 ± 0.40^b	5.14 ± 0.03^a	0.19 ± 0.00^a	5.40 ± 0.00^ac	22.90 ± 1.89^ab	4.61 ± 1.26^b	7.63 ± 0.02^bc
	10	2.85 ± 0.12^a	4.47 ± 0.08^cd	5.11 ± 0.05^ac	0.31 ± 0.00^b	5.64 ± 0.60^ac	31.21 ± 2.72^a	5.78 ± 0.97^a	10.32 ± 0.02^a
	15	3.87 ± 0.62^b	4.13 ± 0.19^ad	5.15 ± 0.07^a	0.23 ± 0.00^a	4.26 ± 0.11^bc	22.47 ± 6.27^ab	5.10 ± 0.64^ab	7.58 ± 2.21^bc
	20	3.81 ± 0.07^b	4.10 ± 0.12^ad	5.15 ± 0.01^a	0.76 ± 0.03^c	4.96 ± 0.35^bc	22.10 ± 4.19^ab	5.65 ± 0.22^a	7.90 ± 1.99^ac
	25	3.45 ± 0.22^bc	4.17 ± 0.24^ad	5.17 ± 0.03^a	0.59 ± 0.04^d	4.89 ± 1.30^bc	23.29 ± 9.93^ab	5.84 ± 0.09^a	8.53 ± 2.62^ac
	30	2.69 ± 0.07a	4.74 ± 0.01^c	5.14 ± 0.00^a	0.79 ± 0.14^c	5.07 ± 0.22^bc	24.58 ± 6.34^ab	5.73 ± 0.41^a	6.79 ± 1.58^bc
	35	2.87 ± 0.73^ac	3.97 ± 0.08^a	5.39 ± 0.07^b	0.50 ± 0.00^e	5.16 ± 0.56^bc	27.79 ± 2.78^ab	7.71 ± 0.24^c	6.23 ± 0.25^bc
	40	2.56 ± 0.13^a	4.84 ± 0.50^c	5.06 ± 0.01^c	0.19 ± 0.00^a	5.24 ± 1.00^bc	20.66 ± 8.67^b	9.52 ± 0.00^d	5.35 ± 2.63^b

*Same lowercase letters in a column indicate no significant differences (p > 0.05).

Figure 2. Changes in different microorganism groups of crucian carp fillets during storage at 4°C (A) and −3°C (B) (TVC: total viable counts; CFC: counts of Pseudomonas.; AMB: counts of Aeromonas; H₂S: counts of H₂S-producing bacteria).

Table 2. Regression correlation coefficients between biogenic amines and microbial flora of crucian carp fillets stored at 4°C (CS) and −3°C (PFS).

Storage temperature	Microbial flora	TRM	2-PHE	PUT	CAD	HIM	TYM	SPD	SPM
CS	Total viable counts	NS	NS	0.7118*	NS	NS	NS	NS	0.7236*
	Pseudomonas	NS	NS	NS	NS	NS	NS	NS	0.8272**
	H2S-producing bacteria	NS	NS	NS	NS	NS	NS	NS	0.8509**
	Aeromonas	NS	NS	0.7395*	NS	NS	NS	NS	0.8229**
PFS	Total viable counts	NS	NS	NS	NS	NS	NS	0.9236**	NS
	Pseudomonas	NS	NS	NS	NS	NS	NS	0.8068**	0.6966*
	H2S-producing bacteria	NS	NS	NS	NS	NS	NS	0.7658**	NS
	Aeromonas	NS	NS	NS	NS	NS	NS	0.8285**	NS

NS, not significant;

* p≤0.05;

** p≤0.01.

Table 3. Comparison of phylotype coverage and alpha diversity estimation of the 16S rRNA gene libraries by sequencing on an IlluminaHiSeq2500 platform in crucian carp fillets stored at 4°C (CS) and −3°C (PFS).

Storage time (days)	Total tags	OTUs	Average length	Shannon	Simpson	Chao1	ACE	Goods coverage
CS.d6	60,825	407	253	2.533	0.723	482.886	486.138	0.998
CS.d12	48,209	277	253	2.453	0.68	337.339	354.138	0.998
PFS.d.35	53,703	568	253	2.966	0.542	619.236	623.576	0.998
PFS.d40	54,640	549	253	2.563	0.551	596	602.06	0.998

Figure 3. Rarefaction curve of microbiota in crucian carp fillets stored at 4°C (CS) and −3°C (PFS).

Figure 4. Relative abundance of microbiota based on phylum level (A), family level (B), and genus level (C) in crucian carp fillets stored at 4°C (CS) and −3°C (PFS).

Figure 5. Relative abundance of microbiota at the genus level. Rows in the heat-map represent different genus-level phylotypes, while columns represent different crucian carp samples. The color intensity is proportional to the abundance of OTUs in each row (CS: chilled storage; PFS: partial freezing storage).