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Ascorbic Acid Dipping as a Means of Extending Shelf Life and Improving Microbial Quality of Cut-Up Broiler Parts1
Ascorbic Acid Dipping as a Means of Extending Shelf Life and Improving Microbial Quality of Cut-Up Broiler Parts1 A. S. ARAFA 2 and T. C. CHEN 3 M.A.F.E.S., Poultry Science Department, Mississippi State University, Mississippi State, Mississippi 39762 (Received for publication March 7, 1977)
INTRODUCTION T h e relatively short shelf life of fresh poult r y is a serious p r o b l e m t o t h e p o u l t r y industry. Efforts t o reduce t h e p r o b l e m have included irradiation processing, surface pasteurization, antibiotic t r e a t m e n t , use of edible coating and storage in germicidal ice (Perry et al., 1 9 6 4 ) . N o n e of these t r e a t m e n t s is used t o d a y t o any significant degree in e x t e n d i n g t h e shelf life of eviscerated cut-up refrigerated p o u l t r y . Preservation of p o u l t r y carcasses b y t h e use of edible acids has been d e m o n s t r a t e d by several workers (Kazeniac, 1 9 6 1 ; Perry et al., 1 9 6 4 ; M o u n t n e y and O'Malley, 1 9 6 5 ; Cox et al., 1974). M o u n t n e y et al. ( 1 9 6 4 ) r e p o r t e d t h a t t h e shelf life of p o u l t r y could be e x t e n d e d b y adding 5 0 p . p . m . of h y d r o c h l o r i c acid t o t h e chill water. M o u n t n e y and O'Malley ( 1 9 6 5 ) added 9 acids (acetic, adipic, citric, fumaric, hydrochloric, lactic, malonic, p h o s p h o r i c and succinic) t o chill water of cut-up p o u l t r y parts in a m o u n t s required t o bring the p H . t o 2 . 5 ; and one acid, sorbic, t o bring t h e p H . t o 3 . 1 . T h e y reported t h a t adipic and succinic acids increased shelf life by six days m o r e t h a n the water-chilled samples w h e n t h e p H . of t h e chilling solutions was 2.5 b u t t h e inhibitory effects declined when t h e p H . increased until
n o inhibition was observed at p H . 4.0. Cox et al. ( 1 9 7 4 ) used succinic acid and heat to improve t h e microbiological quality of poultry m e a t . T h e y r e p o r t e d t h a t the effectiveness of succinic acid t r e a t m e n t in destroying bacteria on t h e carcass skin was greater after exposure for 3 min. rather t h a n exposure for 1 min. and as t h e c o n c e n t r a t i o n of succinic acid increased from 1 t o 5%. T h e y further added t h a t unheated 1% succinic acid t r e a t m e n t s increased shelf life of chicken legs 1 t o 2 days. Heated acid, however, caused a c o o k e d appearance and loss of yellow skin color which deteriorated more rapidly with increased acid concentration. Perry et al. ( 1 9 6 4 ) , in a s t u d y on t h e effects of processing with sorbic acid concluded t h a t p o u l t r y parts, h y d r a t e d in ice slush solution of sodium dihydrogen p h o s p h a t e for 2 hr. and sprayed with a h o t ( 1 6 0 ° F . ) solution of 7.5% sorbic acid, had a longer shelf life when c o m p a r e d with the u n t r e a t e d control parts. Refrigeration of p o u l t r y is t h e most import a n t single factor in extending shelf life. In view of t h e past w o r k on t h e use of acids as food preservative, this s t u d y was c o n d u c t e d to determine t h e effect of ascorbic acid as the only antimicrobial agent, on t h e shelf life of refrigerated cut-up p o u l t r y . EXPERIMENTAL PROCEDURES
'Journal Paper No. 3678 of the Mississippi Agricultural and Forestry Experiment Station. 2 Present address: Poultry Science Department, University of Florida, Gainesville, Florida 32611. 3 To whom reprint requests should be sent.
Experiments 1 and 2. Sample preparations. Commercially dressed carcasses were obtained directly from a processing plant. They were packaged in p o l y e t h y l e n e bags, placed in an ice chest, covered with ice and transported to the
99
Downloaded from http://ps.oxfordjournals.org/ at University of Victoria, McPherson Library Serials on April 8, 2015
ABSTRACT Dipping cut-up broiler parts in 1% ascorbic acid solution for 3 min. retarded microbial growth and increased the refrigerated shelf life for 6 to 7 days when compared with water dipped controls. Throughout the entire storage period, ascorbic acid dipped samples had lower microbial counts and coliform most probable numbers than the water dipped controls. Dipping in ascorbic acid had no adverse effect on the organoleptic characteristics of the cooked meat. Additional studies employing phosphoric and hydrochloric acid solutions at pH. 2.75 indicated that the pH. reduction was not the only factor responsible for the microbial reduction observed when broiler parts were dipped in 1% ascorbic acid solution.
100
ARAFA AND CHEN
Coliform most probable number (MPN). Coliform most probable number was determined according to methods described in standard methods for the examination of dairy products (A.P.H.A., 1974). Experiment 3. Microbial reduction by dipping in selected acids. This experiment was designed to determine whether the reduction in microbial counts as a result of ascorbic acid dipping is pH. dependent. Using sterilized peptone water, three 100 ml. portions, in 250 ml. flasks of phosphoric, hydrochloric and ascorbic
acid solutions were made utilizing different concentrations to obtain the same pH. value. Peptone water was used as a control. Ten cut-up broiler parts from five broiler carcasses were prepared in the same manner as in experiment 1 and rinsed for 5 min. in 200 ml. sterilized peptone water. Ten ml. portions of the rinse culture were used to inoculate the three acidic solutions and the control flasks. A pH. of 2.75 was recorded for die acidic solutions while the pH. of the control was 7.00 ± 0.05. All inoculated flasks were placed on a shaker at 150 r.p.m. for 1 hr. Aerobic plate counts were made at 0.5, 20, 40, and 60 min. as described in experiment 1, and the average number of the colonies from the duplicate plates was reported as log bacterial count per ml. This experiment was repeated twice. Experiment 4. Effect of ascorbic acid dipping on color and flavor of raw meat and organoleptic parameters of the cooked parts. Color and odor of the raw broiler parts were judged independently by three members of the laboratory staff at 4 day intervals prior to making bacterial counts. Palatability of both cooked white and dark meat from the control and the 1% ascorbic acid dipped group was
DAYS
FIG. 1. Aerobic microbial counts of cut-up broiler parts dipped in different concentrations of ascorbic acid solutions and stored at 2-4°C. o, 1%; o, 0.5%; •, 0.25%; and •, control.
Downloaded from http://ps.oxfordjournals.org/ at University of Victoria, McPherson Library Serials on April 8, 2015
laboratory. Each carcass was aseptically cut-up into eight parts and the parts from all carcasses were mixed together thoroughly to insure distribution of the microbial populations. Thighs and breasts were randomly divided into 4 groups with the same numbers in each, and were then dipped in either 0%, 0.25%, 0.5%, or 1% ascorbic acid solutions kept at 1 to 2 C. After 3 min., broiler parts were removed from the acid solutions and were drained for 1 min. Then they were packaged individually in commercial unperforated poultry polyethylene bags and the tops of the bags were folded. Twelve replications were made for each group and the prepared samples were then placed in a 3 ± 1 C. refrigerator immediately. Samples for experiment 2 were prepared in the same manner except only 0% and 1% ascorbic acid solutions were used. Microbiological assay. Total microbial counts were made at zero time, and were repeated every four days for a period of 28 days. Bacteriological samples of the broiler parts from the four groups were obtained by swabbing the skin with cotton swabs and the serial dilution was made according to procedures described by Arafa and Chen (1975). Nutrient broth (Difco) was used as a diluent (Levin, 1968). In the first experiment, aerobic plate counts were made in duplicate using plate count agar (Difco), and incubated for 72 hr. at 20 C. In the second experiment, plate counts were made in duplicate using plate count agar (Difco) and Staphylococcus-110 agar (Difco). Plates were incubated for 72 hr. at 20°C. and 48 hr. at 37 C. to determine the total aerobic counts at two incubation temperatures. Counts on Staphylococcus-110 medium were made after 72 hr. of incubation at 37 C. The average number of colonies from the duplicate plates was reported as the number of bacteria per sq. cm. of the skin surface. Both experiments were repeated 3 times.
SHELF LIFE OF BROILERS
20
to
30
10
20
30
DAYS FIG. 2. Microbial counts of cut-up broiler parts dipped in ascorbic acid solution and stored at 2—4°C. A, 20°C. counts; B, 37°C. counts; o, l%;and •, control.
determined by taste panel evaluations. Parts from both groups were deep fat fried at 176.6 C. for 4 min. in a General Electric Mark 313 Deep-Fat-Fryer. The heated samples were allowed to cool for 5 min. before they were coded and served to the panelists. A hedonic
scale scoring sheet was used according to methods described by the Canadian Dept. of Agriculture (1970). Ten experienced panelists evaluated the samples for flavor, tenderness, juiciness and overall satisfaction. Organoleptic evaluations were repeated 3 times on different dates utilizing the same group of panelists. RESULTS AND DISCUSSION
(M
^
O \ (/) 4 IZ ID
'—•—•
O u
o o
2
'0-_
O
.
20 10 DAYS
30
FIG. 3. Staphylococcus-110 medium counts of cut-up broiler parts dipped in ascorbic acid solution and stored at 2—4°C. o, 1%; and •, control.
Effect of ascorbic acid dipping on shelf life of poultry parts. Dipping in different ascrobic acid solutions for 3 min. was shown to retard microbial growth on cut-up parts and increase shelf life when compared with the water dipped control parts (Fig. 1). As the acid concentration in the solution increased, the inhibitory effect was more noticeable and the shelf life was longer. Similar results were reported for succinic acid treatment (Cox et ah, 1974). As judged by off-odors and slime formations, control samples were considered spoiled at 12—14 days of storage at 2 to 4°C. while the 1% ascorbic acid dipped samples were spoiled at 20—21 days of storage at the same temperature. Since the best microbial reduction and shelf life extension effect was obtained by using the 1% ascorbic acid solution, further experiments reported in this study were carried out only at
Downloaded from http://ps.oxfordjournals.org/ at University of Victoria, McPherson Library Serials on April 8, 2015
0
101
102
ARAFA AND CHEN
IT)
o o 20
30
20 40 MINUTES
DAYS
60
FIG. 4. Coliform MPN of cut-up broiler parts dipped in ascorbic acid solution and stored at 2—4 C. o, 1%; and •, control. (The log count/ml is the equivalent for the log count/0.1 sq. in. of skin surface).
FIG. 5. Aerobic microbial counts of rinsed cultures from fresh broiler parts incubated in selected acid solutions at pH. value of 2.75 and peptone water at pH. value of 7.0. o, ascorbic acid; Q, hydrochloric acid; •, phosphoric acid; and •, peptone water.
the 1% level. Dipping of broiler parts in 1% ascorbic acid solutions at 1 to 2 C. for 3 min. decreased the initial total counts on the surface (Fig. 2). During the entire storage period the ascorbic acid dipped parts maintained the lowest microbial count. Staphylococcus-110 medium counts of cut-up parts decreased slightly before leveling off at the 20th day of refrigerated storage (Fig. 3). Ascorbic acid dipped broiler parts had a lower coliform MPN as compared to the controls throughout the entire storage period at 2 to 4 C. (Fig. 4). Microbial reduction by dipping in selected acids. Ascorbic acid solution at a pH. of 2.75 had a better microbial destruction effect when compared with hydrochloric or phosphoric acid solutions at the same pH. (Fig. 5). Hydrochloric acid was slightly more effective in reduction of microbial counts than phosphoric acid in this regard, and the control solution had the highest microbial counts. The pH. of the control
peptone water solution was adjusted to 7.00 while the pH. of the acid solutions was adjusted at 2.75 since the 1% ascorbic acid solution used in this study had a pH. value of 2.75. Lowering the pH. from 7.00 to 2.75 resulted in a various degree of microbial reduction. The results clearly indicated that the effect of ascorbic acid on microorganisms of poultry parts is not a pH. effect. Further studies are underway to determine other possible factors that may be contributing to the microbial reduction effect observed in this report and to reveal the pattern of microbial spoilage and the characteristics of microflora involved with ascorbic acid dipping treatment. Effect of ascorbic acid on color and flavor of raw broiler meat and organoleptic parameter of the cooked parts. The color of the ascorbic acid treated samples was unanimously preferred by the three judges even after the spoilage was evident by the off odor production in both the
TABLE 1.—Mean flavor, tenderness, juiciness and over-all satisfaction scores1 of ascorbic acid dipped, deep fat fried poultry meat Mean scores Treatment
Flavor
Tenderness
Ascorbic acid dipped parts Control parts
7.46 7.47
7.08 7.24
1
Lower scores indicates better acceptability.
Juiciness
Over-all satisfaction
7.24 7.41
7.29 7.42
Downloaded from http://ps.oxfordjournals.org/ at University of Victoria, McPherson Library Serials on April 8, 2015
10
SHELF LIFE OF BROILERS
REFERENCES American Public Health Association, 1974. Standard methods for the examination of dairy products. 13th Edition. APHA, Inc., New York. Arafa, A. S., and T. C. Chen, 1975. Effect of vacuum packaging on microorganisms on cut-up chicken
and in chicken products. J. Food Sci. 40:50—52. Canada Department of Agriculture, 1970. Methods for sensory evaluation of food. Information Division CDA, Ottawa, Canada. Cox, N. A., A. J. Mercuri, B. J. Juven, J. E. Thomson and V. Chew, 1974. Evaluation of succinic acid and heat to improve the microbiological quality of poultry meat. J. Food Sci. 39:985—987. Elliott, R. P., and H. D. Michener, 1961. Microbiological standards and handling code for chilled and frozen foods. A review. Appl. Microbiol. 9:452-468. Kazeniac, S. J., 1961. Chicken flavor. Proc. Flav. Chem. Sym., Campbell Soup Co., 37—56. Levin, R. E., 1968. Detection and incidence of specific species of spoilage bacteria on fish. I. Methodology. Appl. Microbiol. 16:1734-1737. Mountney, G. J., U. B. Blackwood, R. N. Kinsle and J. E. O'Malley, 1964. The effect of 2 hepta-5-Methylbenzi-midazole and hydrochloric acid on the growth of microflora found on poultry carcasses. Poultry Sci. 43:778-780. Mountney, G. J., and J. O'Malley, 1965. Acids as p o u l t r y m e a t preservatives. Poultry Sci. 44:582-586. Perry, G. A., R. L. Lawrence and D. Melnick, 1964. Extension of poultry shelf life by processing with sorbic acid. Food Technol. 18:891-897.
Downloaded from http://ps.oxfordjournals.org/ at University of Victoria, McPherson Library Serials on April 8, 2015
treated and c o n t r o l samples. Odor evaluations agreed with t h e bacterial assay data. T h e ascorbic acid treated samples did n o t develop off o d o r until 6 t o 7 days after t h e control parts. Statistical analysis of the taste panel evaluations for flavor, tenderness, juiciness and overall satisfaction scores showed n o significant differences for ascorbic acid dipped and control, deep fat fried, broiler parts (Table 1). However, acid treated samples had a slightly b e t t e r organoleptic scores. These d a t a indicated t h a t ascorbic acid dipping for 3 min. had n o adverse effect on t h e color of fresh parts or t h e organoleptic characteristics of t h e c o o k e d m e a t .
103
INTRODUCTION T h e relatively short shelf life of fresh poult r y is a serious p r o b l e m t o t h e p o u l t r y industry. Efforts t o reduce t h e p r o b l e m have included irradiation processing, surface pasteurization, antibiotic t r e a t m e n t , use of edible coating and storage in germicidal ice (Perry et al., 1 9 6 4 ) . N o n e of these t r e a t m e n t s is used t o d a y t o any significant degree in e x t e n d i n g t h e shelf life of eviscerated cut-up refrigerated p o u l t r y . Preservation of p o u l t r y carcasses b y t h e use of edible acids has been d e m o n s t r a t e d by several workers (Kazeniac, 1 9 6 1 ; Perry et al., 1 9 6 4 ; M o u n t n e y and O'Malley, 1 9 6 5 ; Cox et al., 1974). M o u n t n e y et al. ( 1 9 6 4 ) r e p o r t e d t h a t t h e shelf life of p o u l t r y could be e x t e n d e d b y adding 5 0 p . p . m . of h y d r o c h l o r i c acid t o t h e chill water. M o u n t n e y and O'Malley ( 1 9 6 5 ) added 9 acids (acetic, adipic, citric, fumaric, hydrochloric, lactic, malonic, p h o s p h o r i c and succinic) t o chill water of cut-up p o u l t r y parts in a m o u n t s required t o bring the p H . t o 2 . 5 ; and one acid, sorbic, t o bring t h e p H . t o 3 . 1 . T h e y reported t h a t adipic and succinic acids increased shelf life by six days m o r e t h a n the water-chilled samples w h e n t h e p H . of t h e chilling solutions was 2.5 b u t t h e inhibitory effects declined when t h e p H . increased until
n o inhibition was observed at p H . 4.0. Cox et al. ( 1 9 7 4 ) used succinic acid and heat to improve t h e microbiological quality of poultry m e a t . T h e y r e p o r t e d t h a t the effectiveness of succinic acid t r e a t m e n t in destroying bacteria on t h e carcass skin was greater after exposure for 3 min. rather t h a n exposure for 1 min. and as t h e c o n c e n t r a t i o n of succinic acid increased from 1 t o 5%. T h e y further added t h a t unheated 1% succinic acid t r e a t m e n t s increased shelf life of chicken legs 1 t o 2 days. Heated acid, however, caused a c o o k e d appearance and loss of yellow skin color which deteriorated more rapidly with increased acid concentration. Perry et al. ( 1 9 6 4 ) , in a s t u d y on t h e effects of processing with sorbic acid concluded t h a t p o u l t r y parts, h y d r a t e d in ice slush solution of sodium dihydrogen p h o s p h a t e for 2 hr. and sprayed with a h o t ( 1 6 0 ° F . ) solution of 7.5% sorbic acid, had a longer shelf life when c o m p a r e d with the u n t r e a t e d control parts. Refrigeration of p o u l t r y is t h e most import a n t single factor in extending shelf life. In view of t h e past w o r k on t h e use of acids as food preservative, this s t u d y was c o n d u c t e d to determine t h e effect of ascorbic acid as the only antimicrobial agent, on t h e shelf life of refrigerated cut-up p o u l t r y . EXPERIMENTAL PROCEDURES
'Journal Paper No. 3678 of the Mississippi Agricultural and Forestry Experiment Station. 2 Present address: Poultry Science Department, University of Florida, Gainesville, Florida 32611. 3 To whom reprint requests should be sent.
Experiments 1 and 2. Sample preparations. Commercially dressed carcasses were obtained directly from a processing plant. They were packaged in p o l y e t h y l e n e bags, placed in an ice chest, covered with ice and transported to the
99
Downloaded from http://ps.oxfordjournals.org/ at University of Victoria, McPherson Library Serials on April 8, 2015
ABSTRACT Dipping cut-up broiler parts in 1% ascorbic acid solution for 3 min. retarded microbial growth and increased the refrigerated shelf life for 6 to 7 days when compared with water dipped controls. Throughout the entire storage period, ascorbic acid dipped samples had lower microbial counts and coliform most probable numbers than the water dipped controls. Dipping in ascorbic acid had no adverse effect on the organoleptic characteristics of the cooked meat. Additional studies employing phosphoric and hydrochloric acid solutions at pH. 2.75 indicated that the pH. reduction was not the only factor responsible for the microbial reduction observed when broiler parts were dipped in 1% ascorbic acid solution.
100
ARAFA AND CHEN
Coliform most probable number (MPN). Coliform most probable number was determined according to methods described in standard methods for the examination of dairy products (A.P.H.A., 1974). Experiment 3. Microbial reduction by dipping in selected acids. This experiment was designed to determine whether the reduction in microbial counts as a result of ascorbic acid dipping is pH. dependent. Using sterilized peptone water, three 100 ml. portions, in 250 ml. flasks of phosphoric, hydrochloric and ascorbic
acid solutions were made utilizing different concentrations to obtain the same pH. value. Peptone water was used as a control. Ten cut-up broiler parts from five broiler carcasses were prepared in the same manner as in experiment 1 and rinsed for 5 min. in 200 ml. sterilized peptone water. Ten ml. portions of the rinse culture were used to inoculate the three acidic solutions and the control flasks. A pH. of 2.75 was recorded for die acidic solutions while the pH. of the control was 7.00 ± 0.05. All inoculated flasks were placed on a shaker at 150 r.p.m. for 1 hr. Aerobic plate counts were made at 0.5, 20, 40, and 60 min. as described in experiment 1, and the average number of the colonies from the duplicate plates was reported as log bacterial count per ml. This experiment was repeated twice. Experiment 4. Effect of ascorbic acid dipping on color and flavor of raw meat and organoleptic parameters of the cooked parts. Color and odor of the raw broiler parts were judged independently by three members of the laboratory staff at 4 day intervals prior to making bacterial counts. Palatability of both cooked white and dark meat from the control and the 1% ascorbic acid dipped group was
DAYS
FIG. 1. Aerobic microbial counts of cut-up broiler parts dipped in different concentrations of ascorbic acid solutions and stored at 2-4°C. o, 1%; o, 0.5%; •, 0.25%; and •, control.
Downloaded from http://ps.oxfordjournals.org/ at University of Victoria, McPherson Library Serials on April 8, 2015
laboratory. Each carcass was aseptically cut-up into eight parts and the parts from all carcasses were mixed together thoroughly to insure distribution of the microbial populations. Thighs and breasts were randomly divided into 4 groups with the same numbers in each, and were then dipped in either 0%, 0.25%, 0.5%, or 1% ascorbic acid solutions kept at 1 to 2 C. After 3 min., broiler parts were removed from the acid solutions and were drained for 1 min. Then they were packaged individually in commercial unperforated poultry polyethylene bags and the tops of the bags were folded. Twelve replications were made for each group and the prepared samples were then placed in a 3 ± 1 C. refrigerator immediately. Samples for experiment 2 were prepared in the same manner except only 0% and 1% ascorbic acid solutions were used. Microbiological assay. Total microbial counts were made at zero time, and were repeated every four days for a period of 28 days. Bacteriological samples of the broiler parts from the four groups were obtained by swabbing the skin with cotton swabs and the serial dilution was made according to procedures described by Arafa and Chen (1975). Nutrient broth (Difco) was used as a diluent (Levin, 1968). In the first experiment, aerobic plate counts were made in duplicate using plate count agar (Difco), and incubated for 72 hr. at 20 C. In the second experiment, plate counts were made in duplicate using plate count agar (Difco) and Staphylococcus-110 agar (Difco). Plates were incubated for 72 hr. at 20°C. and 48 hr. at 37 C. to determine the total aerobic counts at two incubation temperatures. Counts on Staphylococcus-110 medium were made after 72 hr. of incubation at 37 C. The average number of colonies from the duplicate plates was reported as the number of bacteria per sq. cm. of the skin surface. Both experiments were repeated 3 times.
SHELF LIFE OF BROILERS
20
to
30
10
20
30
DAYS FIG. 2. Microbial counts of cut-up broiler parts dipped in ascorbic acid solution and stored at 2—4°C. A, 20°C. counts; B, 37°C. counts; o, l%;and •, control.
determined by taste panel evaluations. Parts from both groups were deep fat fried at 176.6 C. for 4 min. in a General Electric Mark 313 Deep-Fat-Fryer. The heated samples were allowed to cool for 5 min. before they were coded and served to the panelists. A hedonic
scale scoring sheet was used according to methods described by the Canadian Dept. of Agriculture (1970). Ten experienced panelists evaluated the samples for flavor, tenderness, juiciness and overall satisfaction. Organoleptic evaluations were repeated 3 times on different dates utilizing the same group of panelists. RESULTS AND DISCUSSION
(M
^
O \ (/) 4 IZ ID
'—•—•
O u
o o
2
'0-_
O
.
20 10 DAYS
30
FIG. 3. Staphylococcus-110 medium counts of cut-up broiler parts dipped in ascorbic acid solution and stored at 2—4°C. o, 1%; and •, control.
Effect of ascorbic acid dipping on shelf life of poultry parts. Dipping in different ascrobic acid solutions for 3 min. was shown to retard microbial growth on cut-up parts and increase shelf life when compared with the water dipped control parts (Fig. 1). As the acid concentration in the solution increased, the inhibitory effect was more noticeable and the shelf life was longer. Similar results were reported for succinic acid treatment (Cox et ah, 1974). As judged by off-odors and slime formations, control samples were considered spoiled at 12—14 days of storage at 2 to 4°C. while the 1% ascorbic acid dipped samples were spoiled at 20—21 days of storage at the same temperature. Since the best microbial reduction and shelf life extension effect was obtained by using the 1% ascorbic acid solution, further experiments reported in this study were carried out only at
Downloaded from http://ps.oxfordjournals.org/ at University of Victoria, McPherson Library Serials on April 8, 2015
0
101
102
ARAFA AND CHEN
IT)
o o 20
30
20 40 MINUTES
DAYS
60
FIG. 4. Coliform MPN of cut-up broiler parts dipped in ascorbic acid solution and stored at 2—4 C. o, 1%; and •, control. (The log count/ml is the equivalent for the log count/0.1 sq. in. of skin surface).
FIG. 5. Aerobic microbial counts of rinsed cultures from fresh broiler parts incubated in selected acid solutions at pH. value of 2.75 and peptone water at pH. value of 7.0. o, ascorbic acid; Q, hydrochloric acid; •, phosphoric acid; and •, peptone water.
the 1% level. Dipping of broiler parts in 1% ascorbic acid solutions at 1 to 2 C. for 3 min. decreased the initial total counts on the surface (Fig. 2). During the entire storage period the ascorbic acid dipped parts maintained the lowest microbial count. Staphylococcus-110 medium counts of cut-up parts decreased slightly before leveling off at the 20th day of refrigerated storage (Fig. 3). Ascorbic acid dipped broiler parts had a lower coliform MPN as compared to the controls throughout the entire storage period at 2 to 4 C. (Fig. 4). Microbial reduction by dipping in selected acids. Ascorbic acid solution at a pH. of 2.75 had a better microbial destruction effect when compared with hydrochloric or phosphoric acid solutions at the same pH. (Fig. 5). Hydrochloric acid was slightly more effective in reduction of microbial counts than phosphoric acid in this regard, and the control solution had the highest microbial counts. The pH. of the control
peptone water solution was adjusted to 7.00 while the pH. of the acid solutions was adjusted at 2.75 since the 1% ascorbic acid solution used in this study had a pH. value of 2.75. Lowering the pH. from 7.00 to 2.75 resulted in a various degree of microbial reduction. The results clearly indicated that the effect of ascorbic acid on microorganisms of poultry parts is not a pH. effect. Further studies are underway to determine other possible factors that may be contributing to the microbial reduction effect observed in this report and to reveal the pattern of microbial spoilage and the characteristics of microflora involved with ascorbic acid dipping treatment. Effect of ascorbic acid on color and flavor of raw broiler meat and organoleptic parameter of the cooked parts. The color of the ascorbic acid treated samples was unanimously preferred by the three judges even after the spoilage was evident by the off odor production in both the
TABLE 1.—Mean flavor, tenderness, juiciness and over-all satisfaction scores1 of ascorbic acid dipped, deep fat fried poultry meat Mean scores Treatment
Flavor
Tenderness
Ascorbic acid dipped parts Control parts
7.46 7.47
7.08 7.24
1
Lower scores indicates better acceptability.
Juiciness
Over-all satisfaction
7.24 7.41
7.29 7.42
Downloaded from http://ps.oxfordjournals.org/ at University of Victoria, McPherson Library Serials on April 8, 2015
10
SHELF LIFE OF BROILERS
REFERENCES American Public Health Association, 1974. Standard methods for the examination of dairy products. 13th Edition. APHA, Inc., New York. Arafa, A. S., and T. C. Chen, 1975. Effect of vacuum packaging on microorganisms on cut-up chicken
and in chicken products. J. Food Sci. 40:50—52. Canada Department of Agriculture, 1970. Methods for sensory evaluation of food. Information Division CDA, Ottawa, Canada. Cox, N. A., A. J. Mercuri, B. J. Juven, J. E. Thomson and V. Chew, 1974. Evaluation of succinic acid and heat to improve the microbiological quality of poultry meat. J. Food Sci. 39:985—987. Elliott, R. P., and H. D. Michener, 1961. Microbiological standards and handling code for chilled and frozen foods. A review. Appl. Microbiol. 9:452-468. Kazeniac, S. J., 1961. Chicken flavor. Proc. Flav. Chem. Sym., Campbell Soup Co., 37—56. Levin, R. E., 1968. Detection and incidence of specific species of spoilage bacteria on fish. I. Methodology. Appl. Microbiol. 16:1734-1737. Mountney, G. J., U. B. Blackwood, R. N. Kinsle and J. E. O'Malley, 1964. The effect of 2 hepta-5-Methylbenzi-midazole and hydrochloric acid on the growth of microflora found on poultry carcasses. Poultry Sci. 43:778-780. Mountney, G. J., and J. O'Malley, 1965. Acids as p o u l t r y m e a t preservatives. Poultry Sci. 44:582-586. Perry, G. A., R. L. Lawrence and D. Melnick, 1964. Extension of poultry shelf life by processing with sorbic acid. Food Technol. 18:891-897.
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treated and c o n t r o l samples. Odor evaluations agreed with t h e bacterial assay data. T h e ascorbic acid treated samples did n o t develop off o d o r until 6 t o 7 days after t h e control parts. Statistical analysis of the taste panel evaluations for flavor, tenderness, juiciness and overall satisfaction scores showed n o significant differences for ascorbic acid dipped and control, deep fat fried, broiler parts (Table 1). However, acid treated samples had a slightly b e t t e r organoleptic scores. These d a t a indicated t h a t ascorbic acid dipping for 3 min. had n o adverse effect on t h e color of fresh parts or t h e organoleptic characteristics of t h e c o o k e d m e a t .
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