Ohio State University Extension Bulletin

Research and Reviews: Meat 2001

Special Circular 183-02

Reduction of Bacterial Contamination on Pork by Using a Lactic Acid Dip Solutions

Results and Discussion

Both Experiments 1 and 2 show the same trend that a 2 % (v/v) lactic acid dip could reduce bacterial counts (Table 1) (P < 0.01). Moreover, lactic acid prolongs the shelf life because the number of total bacterial count was decreased whereas the bacterial count for the control group increased which longer storage (P < 0.01). This result is supported by El-Khateib et al. (1992) and they reported that 2% (v/v) lactic acid decreases the count of Listeria monocytogenes on the meat surface significantly when compared with the control treatment. Woolthuis and Smulders (1985) also observed that when calf carcass were spray with 1.25% lactic acid and were measured 24 hours post mortem that aerobic colony count was reduce by 0.8 CFU/cm²on the breast.

Table 1 Total bacterial count (log CFU/g) of control and lactic acid dipped treated samples stored for different times.

Storage time Total bacterial count (log CFU/g)

Control Lactic

Exp.1
2%(v/v) Lactic acid 0 min 5.89 ^ab 5.75^b

30 min 5.74^b 4.28^c

1 day 5.92^ab 4.61^c

2 days 6.07^a 4.76^c

3 days 6.15^a 5.03^c

Average Exp.1 5.95^d 5.00^e

Exp.2
2%(v/v) Lactic acid 0 min 5.68^c 6.86^ab

30 min 6.66^b 7.11^ab

3 days 7.24^a 5.81^c

5 days 7.16^ab 5.52^c

7 days 7.15^ab 5.53^c

Average Exp.2 6.78^d 6.17^e

^abcMeans with different superscripts, in different experiments, in both row and column are significantly different (P < 0.01).
^deMeans with different superscripts on the same row are significantly different (P < 0.01).

In Experiment 1, the percentage of drip loss in the treated group was significantly (P < 0.01) higher than in the control group but there was no significant difference in Experiment 2 (Tables 2 and 3). With longer storage times the percentage of drip loss was significantly (P < 0.01) higher in both experiment. There was no significantly different in meat color between the control and treated group (Table 4). These data show the same trend as Woolthuis and Smulders (1985) who reported that concentrations up to 1.25% (v/v) of lactic acid did not produce discoloration and concentrations up to 2% (v/v) were not significantly different from controls in terms of flavor.

Table 2. Percentage of drip loss of control and lactic acid dipped treated pork.

Treatment % Drip loss
(Average of 1, 2, and 3 days)

Exp.1 Control 0.95^b

Lactic acid 2% (v/v) 1.94^a

(Average of 3, 5, and 7 days)

Exp.2 Control 3.66^c

Lactic acid 2% (v/v) 3.78^c

^abMeans with difference superscripts on the same column, in different experiments are significantly different (P < 0.01).
^cNo significant difference.

Table 3. Percentage drip loss of pork stored for different times.

Storage time % Drip loss
(Average of control and lactic acid)

Exp.1 1 day 0.90^b

2 days 0.89^b

3 days 1.87^a

Exp.2 3 days 2.54^b

5 days 3.75^ab

7 days 4.86^a

^abMeans with difference superscripts in the same column, in different experiments, are significantly different (P < 0.01).

Table 4. Color score of control and lactic acid dipped treated pork.

Treatment Color score^a
(Average of 3, 5, and 7 days)

Exp.2 Control 64.93^b

Lactic acid 2% (v/v) 64.80^b

^aGoefo meter, scale 1 = light, 100 = dark.
^bNo significant difference.

Table 5. Color score of pork stored at 0 to 4⁰C for different periods of time.

Storage time Color score ^a
(Average of control and lactic acid)

3 days 66.31^b

5 days 66.22^b

7 days 62.06^c

^aGoefo meter, scale 1 = light,100 = dark.
^bcMeans with different superscripts in the same column are significantly different (P < 0.01).

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Table 1 Total bacterial count (log CFU/g) of control and lactic acid dipped treated samples stored for different times.
Storage time		Total bacterial count (log CFU/g)
Storage time		Control	Lactic
Exp.1 2%(v/v) Lactic acid	0 min	5.89 ^ab	5.75^b
	30 min	5.74^b	4.28^c
	1 day	5.92^ab	4.61^c
	2 days	6.07^a	4.76^c
	3 days	6.15^a	5.03^c
Average Exp.1		5.95^d	5.00^e
Exp.2 2%(v/v) Lactic acid	0 min	5.68^c	6.86^ab
	30 min	6.66^b	7.11^ab
	3 days	7.24^a	5.81^c
	5 days	7.16^ab	5.52^c
	7 days	7.15^ab	5.53^c
Average Exp.2		6.78^d	6.17^e
^abcMeans with different superscripts, in different experiments, in both row and column are significantly different (P < 0.01). ^deMeans with different superscripts on the same row are significantly different (P < 0.01).

Table 2. Percentage of drip loss of control and lactic acid dipped treated pork.
	Treatment	% Drip loss (Average of 1, 2, and 3 days)
Exp.1	Control	0.95^b
Exp.1	Lactic acid 2% (v/v)	1.94^a
		(Average of 3, 5, and 7 days)
Exp.2	Control	3.66^c
Exp.2	Lactic acid 2% (v/v)	3.78^c
^abMeans with difference superscripts on the same column, in different experiments are significantly different (P < 0.01). ^cNo significant difference.

Table 3. Percentage drip loss of pork stored for different times.
	Storage time	% Drip loss (Average of control and lactic acid)
Exp.1	1 day	0.90^b
	2 days	0.89^b
	3 days	1.87^a
Exp.2	3 days	2.54^b
	5 days	3.75^ab
	7 days	4.86^a
^abMeans with difference superscripts in the same column, in different experiments, are significantly different (P < 0.01).

Table 4. Color score of control and lactic acid dipped treated pork.
	Treatment	Color score^a (Average of 3, 5, and 7 days)
Exp.2	Control	64.93^b
	Lactic acid 2% (v/v)	64.80^b
^aGoefo meter, scale 1 = light, 100 = dark. ^bNo significant difference.

Table 5. Color score of pork stored at 0 to 4⁰C for different periods of time.
Storage time	Color score ^a (Average of control and lactic acid)
3 days	66.31^b
5 days	66.22^b
7 days	62.06^c
^aGoefo meter, scale 1 = light,100 = dark. ^bcMeans with different superscripts in the same column are significantly different (P < 0.01).