Safety Assessment of Crayfish (Astacus Leptodactylus ESCH., 1823) from Microbial Load and Biogenic Amines Signature: Impact of Post-Catch Icing and Frozen Storage

Figures & data

Table 1  HPLC program elution for the quantification of biogenic amines analysis in crayfish (A. leptodactylus)

Time (min)	Acetonitrile (%)	Water (%)
0	50	50
1	50	50
5	65	35
6	75	25
10	80	20
15	90	10

Table 2  Mean recoveries of biogenic amines from crayfish (A. leptodactylus)

Type of biogenic amines	Mean ± SD*
Putrescine	65 ± 2.8
Cadaverine	80 ± 2.2
Histamine	72 ± 3.5
Internal standard	88 ± 2.9
Tyramine	85 ± 2.5

*Means of six repetitions. SD: standard deviation.

Figure 1  HPLC chromatogram and peak identification recorded for mixer of standard biogenic amines and an extract of crayfish (A. leptodactylus).

Table 3  Biogenic amines concentration (μg/g flesh)^A in crayfish (A. leptodactylus) during post-catch icing and frozen storage

		Ice storage (days)		Frozen storage (days)
BAs	0 (fresh)	1	2	30	60	90
Histamine	ND	ND	4.99 ± 1.98^a	8.67 ± 3.78^a	32.63 ± 3.12^b	110.22 ± 5.78^c
Tyramine	ND	ND	1.69 ± 0.28^a	4.22 ± 1.75^ab	8.35 ± 2.07^b	57.37 ± 4.09^c
Cadaverine	50.57 ± 4.07^a	99.63 ± 5.98^b	107.28 ± 4.96^bc	119.14 ± 5.35^c	157.52 ± 6.23^d	231.15 ± 5.41^e
Putrescine	5.33 ± 1.46^a	7.04 ± 2.62^a	10.42 ± 2.16^b	14.93 ± 3.45^b	44.77 ± 4.34^c	88.29 ± 1.89^d

^AData are expressed as mean ± standard deviation (n = 3). ND: Not detected. Same letters for mean values within a row denote no significant differences (P < 0.05).

Table 4  Bacterial changes (10³ CFU/g flesh)^A of crayfish (A. leptodactylus) during post-catch icing and frozen storage

		Ice storage (days)		Frozen storage (days)
Bacteria	0 (fresh)	1	2	30	60	90
Mesophilic	3.19 ± 0.11^a	3.47 ± 0.08^ab	3.71 ± 0.08^bc	3.09 ± 0.32^a	3.27 ± 0.07^a	3.89 ± 0.11^c
Psychrotrophic	4.71 ± 0.14^a	4.85 ± 0.15^ab	5.24 ± 0.09^bc	4.73 ± 0.11^a	4.91 ± 0.20^ab	5.59 ± 0.13^c
Pseudomonas spp.	ND	2.90 ± 0.09^a	3.58 ± 0.16^b	2.22 ± 0.33^c	ND	ND

^AData are expressed as mean ± standard deviation (n = 3). ND: Not detected. Same letters for mean values within a row denote no significant differences (P < 0.05).

Figure 2  Biogenic amines index (μg/g flesh) in crayfish (A. leptodactylus) during short-term post-catch icing and frozen storage. (The dotted line represents tolerable maximum level. Error bar not shown.)