Shelf life of fresh chilled pork as affected by antimicrobial intervention with nisin, tea polyphenols, chitosan, and their combination

Figures & data

Table 1. Effect of different treatments on bacterial counts changes of fresh pork at 4°C for 11 days

Treatments	Time (d)
	0	1	3	5	7	9	11
TVC (logCFU/g)
Control	4.76 ± 0.24^eA	4.85 ± 0.09^eA	5.47 ± 0.28^dA	6.53 ± 0.21^A	6.78 ± 0.24^bcA	7.02 ± 0.14^abA	7.2 ± 0.11^aA
Nisin	4.69 ± 0.11^eA	4.42 ± 0.15^dBC	4.85 ± 0.09^dB	5.68 ± 0.13^BC	5.89 ± 0.07b^cBC	6.09 ± 0.16b^BC	6.36 ± 0.17^aC
TPs	4.74 ± 0.16^deA	4.54 ± 0.10^eB	4.97 ± 0.27^dB	5.95 ± 0.17^cB	6.11.±0.14^bcB	6.33 ± 0.13^abB	6.62 ± 0.12^aB
Chitosan	4.63 ± 0.21^cA	4.38 ± 0.22^dBC	4.78 ± 034^cB	5.47 ± 0.08^bCD	5.92 ± 0.23^aBC	6.16 ± 0.07^aBC	6.29 ± 0.15^aC
N-TP-C	4.71 ± 0.14^cA	4.14 ± 0.16^dC	4.52 ± 0.07^cB	5.19 ± 0.15^bD	5.64 ± 0.34^aC	5.91 ± 0.17^aC	5.95 ± 0.08^aD
lactic acid bacteria (logCFU/g)
Control	3.53 ± 0.12^dA	3.45 ± 0.07^dA	4.32 ± 0.16^cA	4.53 ± 0.08^cA	4.49 ± 0.11^cA	4.83 ± 0.23^bA	5.12 ± 0.14^aA
Nisin	3.57 ± 0.15^eA	3.23 ± 0.^11fABC	3.55 ± 0.06^eB	3.86 ± 0.12^dBC	4.11 ± 0.07^cB	4.37 ± 0.16^bB	4.57 ± 0.09^aB
TPs	3.48 ± 0.09^dA	3.38 ± 0.24^dAB	3.67 ± 0.13^cdB	4.07 ± 0.33b^B	3.93.±0.16^bcB	4.23 ± 0.08^abB	4.46 ± 0.17^aBC
Chitosan	3.55 ± 0.13^cdA	3.12 ± 0.17^eBC	3.31 ± 0.15^deC	3.64 ± 0.08^bcC	3.87 ± 0.25^bB	4.26 ± 0.22^aB	4.22 ± 0.18^aCD
N-TP-C	3.46 ± 0.16^bA	3.07 ± 0.08^aC	3.04 ± 0.11^bD	3.57 ± 0.25^aC	3.82 ± 0.13^aB	3.89 ± 0.06^aC	4.07 ± 0.14^aD
pseudomonas spp (logCFU/g)
Control	2.75 ± 0.06^aA	2.82 ± 0.09^aA	4.15 ± 0.14^cA	4.68 ± 0.21^bA	5.44 ± 0.07^aA	5.65 ± 0.15^aA	5.71.±0.24^aA
Nisin	2.72 ± 0.11^eA	2.47 ± 0.12^fB	2.86 ± 0.08^eC	3.74 ± 0.14^dBC	4.05 ± 0.21^cBC	4.33 ± 0.06^bB	4.59 ± 0.12^aBC
TPs	2.74 ± 0.09^fA	2.51 ± 0.07^gB	3.19 ± 0.16^eB	3.82 ± 0.07^cB	4.23 ± 0.08^cB	4.62 ± 0.23^bB	4.86 ± 0.17^aB
Chitosan	2.66 ± 0.15^dA	2.31 ± 0.15^eB	2.85 ± 0.10^dC	3.52 ± 0.11^cC	3.97 ± 0.16^bC	3.89 ± 0.19^bC	4.37 ± 0.08^aCD
N-TP-C	2.71 ± 0.08^dA	2.09 ± 0.13^fC	2.34 ± 0.08^eD	3.23 ± 0. 17^cD	3.42 ± 0.09^cD	3.65 ± 0.12^bC	4.13 ± 0.16^aD
staphylococcus spp. (logCFU/g)
Control	3.14 ± 0.12^eA	3.34 ± 0.10^eA	3.54 ± 0.08^dA	3.79 ± 0.07^cA	4.07 ± 0.12^bA	4.12 ± 0.06^bA	4.32 ± 0.11^aA
Nisin	3.18 ± 0.09^dA	2.74 ± 0.08^eB	2.83 ± 0.11^eB	3.14 ± 0.09^dB	3.27 ± 0.13^cB	3.41 ± 0.08^bB	3.63 ± 0.21^aB
TPs	3.16 ± 0.07^bA	2.81 ± 0.13^cdB	2.75 ± 0.15^dB	2.98 ± 0.05^bcB	3.02 ± 0.09^bC	3.18 ± 0.15^bC	3.45 ± 0.08^aB
Chitosan	3.12 ± 0.10^aA	2.62 ± 0.09^dBC	2.69 ± 0.06^dBC	2.76 ± 0.11^cdC	2.92 ± 0.05^bcC	3.07 ± 0.16^abC	3.21 ± 0.06^aC
N-TP-C	3.15 ± 0.08^aA	2.49 ± 0.12^eC	2.52 ± 0.09^eC	2.66 ± 0.13^deC	2.84 ± 0.07^cdC	2.96 ± 0.12^bcC	3.09 ± 0.13^abC
brochothrix thermosphacta (logCFU/g)
Control	2.32 ± 0.16^eA	2.44 ± 0.14^eA	2.62 ± 0.09^dA	2.74 ± 0.12^cdA	2.86 ± 0.07^cA	3.11 ± 0.10^bA	3.48 ± 0.18^aA
Nisin	2.33 ± 0.13^cA	2.08 ± 0.07^dBC	2.29 ± 0.11^cBC	2.31 ± 0.13^cB	2.44 ± 0.09^bcBC	2.62 ± 0.12^abBC	2.73 ± 0.07^aBC
TPs	2.29 ± 0.14^bcA	2.21 ± 0.10^cB	2.38 ± 0.06^bcB	2.49 ± 0.10^bB	2.51 ± 0.17^bB	2.78 ± 0.06^aB	2.95 ± 0.13^aB
Chitosan	2.28 ± 0.09^bcdA	2.14 ± 0.08^dB	2.23 ± 0.13^cdBC	2.42 ± 0.08^abB	2.47 ± 0.11^bB	2.69 ± 0.08^aB	2.82 ± 0.15^aB
N-TP-C	2.35 ± 0.11^abA	1.92 ± 0.11^cC	2.18 ± 0.07^bC	2.37 ± 0.15^abB	2.36 ± 0.08^abC	2.43 ± 0.16^aC	2.53 ± 0.07^aC
enterobacteriaceae (logCFU/g)
Control	2.64 ± 0.13^eA	2.71 ± 0.08^eA	3.02 ± 0.11^dA	4.36 ± 0.27^cA	4.87 ± 0.19^bA	5.18 ± 0.13^aA	5.38 ± 0.15^aA
Nisin	2.62 ± 0.10^deA	2.39 ± 0.17^eB	2.67 ± 0.09^dB	3.56 ± 0.15^cB	3.96 ± 0.15^bB	4.21 ± 0.22^bB	4.61 ± 0.13^aB
TPs	2.64 ± 0.12^eA	2.28 ± 0.14^fB	2.57 ± 0.14^eB	3.38 ± 0.10^dBC	3.75 ± 0.13^cBC	4.05 ± 0.09^bBC	4.56 ± 0.21^aB
Chitosan	2.67 ± 0.08^eA	2.24 ± 0.09^fB	2.55 ± 0.12^eB	3.19 ± 0.13^dC	3.67 ± 0.09^cC	3.89 ± 0.12^bCD	4.48 ± 0.11^aB
N-TP-C	2.61 ± 0.15^eA	1.87 ± 0.13^gC	2.34 ± 0.09^fC	3.07 ± 0.16^dC	3.49 ± 0.12^cC	3.71 ± 0.08^bD	4.06 ± 0.14^aC

Control = no treatment; Nisin = nisin treatment; Tps = tea polyphenols treatment; Chitosan = chitosan treatment; N-TP-C = treatment with nisin, tea polyphenols and chitosan.

Means with different small letters superscripts in the same row are significantly different(p < 0.05).

Means with different capital letters superscripts in the same column are significantly different(p < 0.05).

Figure 1. Changes in total volatile basic nitrogen(TVB-N) of fresh pork samples at 4°C for 11 days. CK: control with no treatment; Nisin = nisin treatment; TPs = tea polyphenols treatment; Chitosan = chitosan treatment; N-TP-C = treatment with nisin, tea polyphenols, and chitosan

Figure 2. Changes in pH value of fresh pork samples at 4°C for 11 days. CK: control with no treatment; Nisin = nisin treatment; TPs = tea polyphenols treatment; Chitosan = chitosan treatment; N-TP-C = treatment with nisin, tea polyphenols, and chitosan

Table 2. Effect of different treatments on Lightness (L),Redness (a) and Yellowness (b) changes of fresh pork at 4°C for 11 days

Treatments	Time (d)
	0	1	3	5	7	9	11
Redness (a)
Control	7.62 ± 0.34^aA	7.87 ± 0.5^aA	6.94 ± 0.22^bB	5.76 ± 0.36^cB	4.65 ± 0.44^dB	4.27 ± 0.22^deB	3.86 ± 0.47^eB
Nisin	7.55 ± 0.51^aA	7.64 ± 0.42^aA	7.34 ± 0.39^aAB	6.36 ± 0.18^bAB	5.17 ± 0.32^cAB	4.85 ± 0.45^dAB	4.39 ± 0.68^dAB
TPs	7.61 ± 0.26^aA	7.59 ± 0.65^aA	7.45 ± 0.25^aAB	6.09 ± 0.27^bAB	4.83 ± 0.38^cB	4.62 ± 0.36^cAB	4.28 ± 0.42^cAB
Chitosan	7.56 ± 0.38^aA	7.58 ± 0.19^aA	7.31 ± 0.41^aA	6.52 ± 0.16^bA	5.46 ± 0.67^cAB	5.01 ± 0.19^cdA	4.56 ± 0.19^dA
N-TP-C	7.53 ± 0.47^aA	7.81 ± 0.27^aA	7.23 ± 0.32^aA	6.48 ± 0.54^bA	5.82 ± 0.12^cA	5.23 ± 0.45^cdA	4.92 ± 0.28^dA
Yellowness (b)
Control	5.46 ± 0.35^aA	5.73 ± 0.45^abA	6.22 ± 0.23^bcA	6.05 ± 0.41^abA	6.76 ± 0.32^cA	7.52 ± 0.28^dA	8.48 ± 0.35^eA
Nisin	5.58 ± 0.24^aA	5.65 ± 0.31^aA	5.92 ± 0.41^abA	6.04 ± 0.24^abA	6.36 ± 0.39^bA	6.94 ± 0.37^cB	7.17 ± 0.28^cBC
TPs	5.76 ± 0.41^aA	5.67 ± 0.44^aA	5.85 ± 0.26^aA	5.93 ± 0.26^aA	6.07 ± 0.32^abA	6.58 ± 0.23^bBC	7.61 ± 0.46^cB
Chitosan	5.94 ± 0.36^aA	5.82 ± 0.29^aA	5.77 ± 0.28^aA	5.89 ± 0.32^aA	6.12 ± 0.45^aA	6.34 ± 0.25^aC	6.93 ± 0.31^bC
N-TP-C	5.65 ± 0.19^aA	5.98 ± 0.37^aA	5.69 ± 0.34^aA	5.86 ± 0.48^aA	6.09 ± 0.26^aA	6.25 ± 0.34^abC	6.82 ± 0.22^bC
Lightness (L)
Control	56.87 ± 1.51^aA	56.68 ± 0.95^aA	55.75 ± 1.47^abA	53.37 ± 0.67^bA	50.24 ± 1.21^cC	45.61 ± 1.39^dB	45.22 ± 2.08^dB
Nisin	56.50 ± 2.62^aA	55.83 ± 1.46^aA	55.64 ± 0.93^aA	56.04 ± 1.52^aA	51.79 ± 0.77^bC	47.25 ± 1.36^cAB	46.25 ± 0.84^cB
TPs	56.68 ± 0.94^aA	56.17 ± 1.55^aA	55.92 ± 2.42^aA	55.78 ± 1.34^aA	52.36 ± 0.85^bBC	47.79 ± 2.23^cAB	46.9 ± 1.56^cB
Chitosan	55.89 ± 2.09^aA	55.95 ± 1.38^aA	56.12 ± 0.78^aA	55.81 ± 1.67^aA	54.27 ± 2.14^aAB	48.13 ± 0.95^bAB	47.32 ± 1.3^bAB
N-TP-C	55.92 ± 1.26^aA	55.37 ± 0.89^aA	54.99 ± 2.43^aA	55.26 ± 1.53^aA	56.11 ± 0.96^aA	49.53 ± 1.61^bA	48.38 ± 1.89^bA

Control = no treatment; Nisin = nisin treatment; Tps = tea polyphenols treatment; Chitosan = chitosan treatment; N-TP-C = treatment with nisin, tea polyphenols and chitosan.

Means with different small letters superscripts in the same row are significantly different(p < 0.05).

Means with different capital letters superscripts in the same column are significantly different(p < 0.05).

Figure 3. Changes in centrifugation loss (a), cooking loss (b) and drip loss (c) of fresh pork samples at 4°C for 11 days. CK: control with no treatment; Nisin = nisin treatment; Tps = tea polyphenols treatment; Chitosan = chitosan treatment; N-TP-C = treatment with nisin, tea polyphenols and chitosan

Figure 4. Changes in TBARS value of fresh pork samples at 4°C for 11 days. CK: control with no treatment; Nisin = nisin treatment; Tps = tea polyphenols treatment; Chitosan = chitosan treatment; N-TP-C = treatment with nisin, tea polyphenols and chitosan

Table 3. Effect of different treatments on shear force and texture changes of fresh pork at 4°C for 11 days

Treatments	Time (d)
	0	1	3	5	7	9	11
Shear force (N)
Control	56.24 ± 1.43^aA	57.06 ± 1.26^aA	55.87 ± 1.43^aA	49.45 ± 1.36^bB	40.77 ± 1.44^cC	34.16 ± 1.92^dC	26.48 ± 2.03^eD
Nisin	56.67 ± 1.87^aA	56.42 ± 1.74^aA	57.38 ± 1.39^aA	55.49 ± 1.28^aA	47.96 ± 1.54^bB	42.63 ± 2.24^cB	37.59 ± 1.61^dBC
TPs	55.25 ± 1.76^aA	55.51 ± 0.97^aA	57.53 ± 1.38^aA	56.37 ± 1.72^aA	47.42.±1.85^bB	41.19 ± 2.07^cB	34.68 ± 1.57^dC
Chitosan	56.08 ± 2.14^aA	55.47 ± 1.82^aA	56.25 ± 1.94^aA	57.41 ± 1.19^aA	49.36 ± 1.66^bAB	43.58 ± 1.27^bB	38.36 ± 1.93^bB
N-TP-C	57.62 ± 1.78^aA	57.04.±1.16^aA	56.45 ± 1.35^aA	55.29 ± 1.09^aA	51.68 ± 1.78^bA	47.16.±1.83^bA	41.84 ± 1.76^dA
Hardness (kg)
Control	2.66 ± 0.24^aA	2.54 ± 0.15^aA	2.41 ± 0.26^bA	1.77 ± 0.18^cC	1.49 ± 0.13^cdC	1.21 ± 0.11^dC	0.78 ± 0.15^eC
Nisin	2.58 ± 0.17^abA	2.64 ± 0.21^aA	2.57 ± 0.11^abA	2.24 ± 0.25^bcAB	1.98 ± 0.19^cAB	1.56 ± 0.17^dAB	1.29 ± 0.18^dAB
TPs	2.62 ± 0.21^aA	2.71 ± 0.14^aA	2.65 ± 0.26^aA	2.36 ± 0.13^aAB	1.83 ± 0.24^bBC	1.51 ± 0.23^bBC	1. 14 ± 0.09^cB
Chitosan	2.73 ± 0.15^aA	2.59 ± 0.09^aA	2.75 ± 0.28^aA	2.18 ± 0.17^bB	2.09 ± 0.15^bAB	1.64 ± 0.15^cAB	1.23 ± 0.12^dAB
N-TP-C	2.85 ± 0.29^aA	2.68 ± 0.18^aA	2.71 ± 0.14^aA	2.56 ± 0.08^abA	2.23 ± 0.21^bA	1.87 ± 0.16^cA	1.45 ± 0.22^dA
Springiness
Control	0.59 ± 0.02^aA	0.58 ± 0.02^aA	0.58 ± 0.03^aA	0.56 ± 0.03^aA	0.50 ± 0.02^bC	0.46 ± 0.01^cC	0.41 ± 0.02^dC
Nisin	0.59 ± 0.01^aA	0.59 ± 0.01^aA	0.58 ± 0.01^aA	0.57 ± 0.02^aA	0.52 ± 0.01^bBC	0.50 ± 0.02^bAB	0.45 ± 0.01^cB
TPs	0.58 ± 0.02^aA	0.59 ± 0.03^aA	0.59 ± 0.01^aA	0.58 ± 0.01^aA	0.53 ± 0.02^bAB	0.49 ± 0.02^cBC	0.44 ± 0.01^dB
Chitosan	0.59 ± 0.01^aA	0.58 ± 0.02^aA	0.58 ± 0.02^aA	0.59 ± 0.02^aA	0.53 ± 0.01^bAB	0.50 ± 0.01^cAB	0.46 ± 0.02^dB
N-TP-C	0.57 ± 0.03^abA	0.59 ± 0.01^aA	0.57 ± 0.02^abA	0.58 ± 0.03^abA	0.55 ± 0.01^bcA	0.53 ± 0.02^cA	0.49 ± 0.01^dA
Chewiness
Control	0.92 ± 0.02^aA	0.89 ± 0.02^abA	0.90 ± 0.02^aA	0.86 ± 0.01^bB	0.78 ± 0.02^cC	0.69 ± 0.01^dD	0.42 ± 0.03^eD
Nisin	0.91 ± 0.03^aA	0.92 ± 0.02^aA	0.92 ± 0.01^aA	0.89 ± 0.02^aAB	0.84 ± 0.01^bAB	0.77 ± 0.02^cBC	0.64 ± 0.02^dC
TPs	0.92 ± 0.01^aA	0.90 ± 0.03^abA	0.92 ± 0.02^aA	0.88 ± 0.01^bAB	0.82 ± 0.02^cB	0.74 ± 0.03^dC	0.61.±0.01^eC
Chitosan	0.92 ± 0.02^aA	0.91 ± 0.02^aA	0.91 ± 0.02^aA	0.90 ± 0.02^aA	0.85 ± 0.01^bAB	0.79 ± 0.02^cAB	0.68 ± 0.03^dB
N-TP-C	0.92 ± 0.02^aA	0.91 ± 0.01^aA	0.92 ± 0.03^aA	0.90 ± 0.02^abA	0.87 ± 0.02^bA	0.82 ± 0.03^cA	0.76 ± 0.01^dA
Resilience
Control	0.45 ± 0.02^aA	0.45 ± 0.01^aA	0.43 ± 0.01^aA	0.37 ± 0.02^bB	0.32 ± 0.01^cC	0.27 ± 0.03^dC	0.21 ± 0.02^eC
Nisin	0.46 ± 0.01^aA	0.46 ± 0.02^aA	0.44 ± 0.03^abA	0.41 ± 0.01^bA	0.36 ± 0.02^cB	0.32 ± 0.02^dB	0.27 ± 0.03^eB
TPs	0.46 ± 0.02^aA	0.44 ± 0.03^aA	0.45 ± 0.02^aA	0.40 ± 0.02^bAB	0.35 ± 0.01^cBC	0.30 ± 0.02^dBC	0.26 ± 0.02^eB
Chitosan	0.45 ± 0.02^abA	0.47 ± 0.03^aA	0.46 ± 0.01^abA	0.43 ± 0.03^bA	0.36 ± 0.02^cB	0.33 ± 0.01^cAB	0.27 ± 0.01^dB
N-TP-C	0.45 ± 0.01^abA	0.45 ± 0.02^abA	0.46 ± 0.02^aA	0.42 ± 0.01^bcA	0.40 ± 0.03^cA	0.36 ± 0.01^dA	0.31 ± 0.02^eA

Control = no treatment; Nisin = nisin treatment; Tps = tea polyphenols treatment; Chitosan = chitosan treatment; N-TP-C = treatment with nisin, tea polyphenols and chitosan.

Means with different small letters superscripts in the same row are significantly different(p < 0.05).

Means with different capital letters superscripts in the same column are significantly different(p < 0.05).

Table 4. Effect of N-TP-C treatments on sensory characteristics to fresh pork at 4°C for 11 days

	Time (d)
	0	1	3	5	7	9	11
color	8.32 ± 0.16^a	8.16 ± 0.22 ^a	7.97 ± 0.19^a	7.45 ± 0.14^b	7.07 ± 0.17^c	6.75 ± 0.21^d	6.24 ± 0.18^e
odor	8.42 ± 0.18^a	8.27 ± 0.15^a	7.94 ± 0.26^a	7.57 ± 0.11^b	6.89 ± 0.15^c	6.26 ± 0.12^d	5.91 ± 0.09^e
texture	8.31 ± 0.14^a	8.09 ± 0.21^a	7.86 ± 0.17^a	7.52 ± 0.15^b	7.13 ± 0.12^c	6.62 ± 0.18^d	6.13 ± 0.23^e

N-TP-C = treatment with nisin, tea polyphenols and chitosan.

Means with different small letters superscripts in the same row are significantly different (p < 0.05).