| Livestock Research for Rural Development 17 (11) 2005 | Guidelines to authors | LRRD News | Citation of this paper |
Buffalo meat is the only future remedy for the nutritional security in India. If the quality gets deteriorated, the meat preserved in refrigerator would impact greatly on the health of consumers. Hence meat samples from five year old sixteen buffalo bulls were analyzed in the fresh state (0 day) and after 4 and 7 days in chiller (4±1oC) and 4, 7, 14, 30, 60 and 75 days in freezer (-10±1oC) in a domestic refrigerator.
The chiller storage increased but freezer decreased the microbial counts (SPC, PC and Coliforms). The values of odour and flavour scores decreased with increasing storage period, whereas, texture, tenderness and juiciness scores showed an increasing trend.
Thus it was concluded that a storage period up to 4 days in chiller and 30 days in freezer could satisfactorily maintain the buffalo meat quality.
Keywords: Buffalo meat, Chiller; Freezer; Microbial; Sensory quality; Storage period
India has 94.13 million numbers of buffaloes, which accounts for 50.6% of the total buffalo population in the world. Presently, India is credited with 1.43 mMT of buffalo meat to its total meat pool (4.65 mMT) contributing 2.03% of world meat production (FAO 2005). Only the buffalo meat has the export potential from our country. Major quantity of meat is exported in frozen form from India to Malaysia and Gulf countries and the annual foreign exchange revenue is around Rs. 1375.04 Crores (APEDA 2005).
In India, most of the meat is purchased by the consumers in fresh or frozen form. To adjust with the fast growing life style of urbanization, they hardly find time to purchase meat daily. Hence they purchase meat in bulk to meet their daily requirements. This meat is stored in refrigerator and consumed on definite intervals. Deterioration of meat quality in refrigerator storage may have great impact on the health of consumers. Considering the importance from consumer viewpoint, a program has been ascribed to study the effect of refrigerator storage on buffalo meat quality. The objective of this study was to determine the microbiological and sensory changes of buffalo meat in domestic refrigerator. Thereby the shelf life of buffalo meat in Chiller and Freezer was established. This study has immense importance to satisfy consumer's query relating to how long buffalo meat can be stored without any deterioration in domestic refrigerator.
Meat samples each weighing 2 kg from shoulder were removed from 16 buffalo bulls of 5 years old from Municipal slaughter house, Tangra, Kolkata. The muscles were then utilized for the study. Four meat samples from different buffalo bulls of same age group were used in a single trial. Age of the buffalo bull carcasses was estimated by observing dentition. The samples were wrapped in highly gas permeable low density polyethylene and transported to the laboratory within 1 hour postmortem.
The samples were kept in chiller (24 hrs at 4±1oC) for ageing (Ziauddin 2003). The separable fat and connective tissue were removed. Then the samples were packed in low density polyethylene, each containing 250 g of meat sample and stored in chiller and freezer respectively for further study. One portion was analyzed in the fresh state (0 day) and the remaining portion after chiller storage (4±1oC) for 4 and 7 days and freezer storage (-10±1oC) for 4, 7, 14, 30, 60 and 75 days in a domestic refrigerator (Godrej Cold Gold Model). The stored samples were analyzed for microbiological changes and sensory attributes.
Total bacterial count in the sample was determined by methods described by APHA (1984). Ready-made Media (Hi-media) was used for the analysis. Serial dilutions for inoculation were prepared according to ICMSF (1986).
Using plate count agar, l ml of suitable dilution was inoculated into petri dishes in duplicate. The plates were incubated at 37 0C for 24-48 hours and colonies were counted and expressed as log 10 cfu/cm2.
Using plate count agar, l ml of suitable dilution was inoculated into petri dishes in duplicate. The plates were incubated at 4±1 0C for 7-14 days and colonies were counted and expressed as log 10 cfu/cm2.
Coliforms were detected by the Touch plate method as described by Himedia Laboratories (FL 002 2003). HiTouch E.coli/Coliform count Flexi plates are specially developed for the enumeration (count) of all coliforms along with the differential count of E.coli. The medium plate was kept in the incubator at 37 0C for 1 hour to evaporate the water droplets formed during storage at refrigerator. Then the flexiplate was carefully opened with the lid on top. The plate with medium was inverted on the test surface and pressed for few seconds. Then the medium plate was lifted and put back into base plate. The lid was closed firmly and the flexiplate was incubated at 35-37 0C for 18-20 hrs. As a result, blue coloured colonies of E.coli and red coloured colonies of other coliforms were observed due to the presence of indicator dye. Then the colonies were estimated per cm2 of the plate.
The samples were cut into cubes of uniform size, cooked in a pressure cooker at 15 pounds pressure for 5 minutes and served warm with code numbers to a trained 10 member consumer panel. They were requested to score their individual preference in a nine point sensory scale. Individual ratings of panel members for the characteristic flavour, juiciness and tenderness, were subjected to statistical analysis as per the methods outlined by Snedecor and Cochran (1994).
In the present investigation, data obtained from the experiment were statistically analyzed and interpreted for different types of estimation following the methodology as outlined by Snedecor and Cochran (1994).
On zero (0) day in the present study, the SPC of buffalo meat after post slaughter was 5.51 ± 0.07 log cfu/ cm2 (Table1). On 4th day of storage, the SPC of chiller (4 ± 1ºC) and freezer (-10 ± 1ºC) stored buffalo meats were 5.70 ± 0.05 and 5.32 ± 0.07 log cfu/ cm2. It was clear from the above result that chilling increased but freezing decreased bacterial load which was also observed by Bhadekar et al (1987). Lawrie (1998) attributed the microbial growth to the growth promoting effect of moisture on microbes in meat stored in chiller. On the 7th and 14th days of freezer storage the SPC were 5.25 ± 0.08 and 5.14 ± 0.15 log cfu/cm2 receptively. Das et al (1988) indicated decline in microbial load from 5.45 in fresh to 4.73 log cfu/g in 15 days frozen buffalo meat at -10 0C. With progress in frozen storage, the SPC of buffalo meat on 30th, 60th and 75th days were 4.79 ±0.07, 4.47± 0.08 and 4.32±0.01 log cfu/cm2 respectively. There existed a significant (P<0.05) difference in spc between these storage periods. Bacchil and Jaiswal (1987) concluded that the bacterial count declined from the initial 1.1 x 10 6 /g to 6.7 x 10 5 /g in 1 month frozen buffalo meat at -100 C. The differences in values were due to the load of bacteria initially present on the meat. Consequently freezing generally produced about a 2 log/g reduction in mesophiles and psychrotrophs numbers (Kraft et al 1979). Though pH increased in frozen meat, bacterial numbers did not reach millions.
The psychrophilic count (PC) of buffalo meat after post slaughter was 4.60± 0.12 log cfu/cm2 (Table 1).
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Table 1. A comparative appraisal between microbiological parameters at different storage periods |
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|
|
0 |
4C* |
4F* |
7C* |
7F* |
14F* |
30F* |
60F* |
75F* |
|
SPC, log cfu/cm2 |
5.51 |
5.70 |
5.32 |
6.82 |
5.25 |
5.14 |
4.79 |
4.47 |
4.32±0.01e |
|
PC, log cfu/cm2 |
4.60 |
4.85 |
4.35 |
5.76 |
4.26 |
4.07 |
3.65 |
3.27 |
3.14±0.20e |
|
Coliforms, cfu/cm2 |
18.00 |
40.00 |
15.00 |
102.00 |
12.00 |
9.00 |
7.00 |
2.00 |
1.00±0.06f |
|
Means bearing different
superscripts differ significantly (P<0.05) |
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Sen and Sharma (2003) observed a PC of 4.34 log cfu/cm2 in fresh buffalo meat. In fact, Kotula (1975) stated that outside of the neck was the site that contained the greatest number of psychrotrophic bacteria, where as the outside flank contained the lowest. Interestingly, the shoulder and forearm muscles utilized in the present study confirmed this finding. On 4 day storage, the PC of chilled (4±1oC) and frozen (-10±1 0C) buffalo meat were 4.85± 0.14 and 4.35± 0.14 log cfu/cm2 respectively. In 7 day chilled meat the PC was observed as 5.76± 0.01 log cfu/cm2. This differed significantly (P< 0.05) with the value of frozen stored meat on the same day. The results showed a PC of 4.26± 0.07 and 4.07± 0.03 log cfu/cm2 on 7th and 14th days of freezer storage respectively. Subsequent storage of 30th, 60th, and 75th days in freezer showed a psychrophilic count of 3.65±0.10, 3.27± 0.07 and 3.14±0.20 log cfu/cm2. Kulkarni et al (1987) reported a decline in PC from an initial count (6.36 log cfu/g) to a 30 days frozen meat PC of 5.70 log cfu/g. The increased enzyme activity of psychrotrophs at low temperature hugely contributed to deterioration of meat quality.
On zero (0) day in the present study the total coliforms in buffalo meat after post slaughter was 18.00±0.82 cfu/cm2 (Table 1). On 4 day storage, the Coliform counts showed an increasing trend in chiller storage and a decreasing trend in freezer. In the present study, the results showed a count of 40.00±1.80 cfu/cm2 in chiller and 15.00±1.23 cfu/cm2 in freezer stored meat. In 7 day chilled meat the TCC was observed as 102.00±0.01 cfu/cm2. This differed significantly (P< 0.05) with the value of frozen stored meat on the same day. On 7 th, 14 th and 30 th days of freezer storage, the results showed a count of 12.00±2.56, 9.00±1.55 and 7.00±0.80 cfu/cm2 respectively. Kulkarni et al (1987) reported count decreased from an initial 5.56 log cfu/cm2 to 5.49 log cfu/cm2 on 30 th day. On 60 th and 75th days of frozen storage the Coliform counts were 2.00±0.18 and 1.00±0.06 cfu/cm2 respectively. Hence the count decreased significantly from the 30 th day of frozen storage. Govt. of India (Thulasi 1997) indicated the microbiological standards for raw meats (chilled/frozen) buffalo meat, veal, mutton and minced meat must contain upto 10/g Esch.coli in 3 out of 5 samples and the remaining 2 may contain 100/g.
On zero (0) day in the present study, the odour score for buffalo meat after post slaughter was 7.5± 0.22 (Table 2). On 4th day of storage, the odour scores were 6.75± 0.30 in chiller (4±10C) and 7.13±0.26 in freezer (-10±1 0C). The scores in these two storage conditions showed that the freezer maintained the odour better than the chiller. Sharma and Sen (2000) and Sen and Sharma (2003) also recorded similar observation. In 7 day chilled meat the odour score was observed as 4.06±0.06. The scores were 7.06±0.17, 6.75±0.19, 6.00±0.20, 5.19±0.10 and 4.94±0.06 on 7,14,30,60 and 75 days of frozen storage respectively. The odour scores differed significantly (P<0.05) on 30th and 60th days of freezer storage.
On zero (0) day in the present study, the flavour score was 7.50±0.16 for the buffalo meat after post slaughter (Table 2).
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Table 2. A comparative appraisal between sensory scores at different storage periods |
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|
|
0 |
4C* |
4F* |
7C* |
7F* |
14F* |
30F* |
60F* |
75F* |
|
Odour |
7.50 |
6.75 |
7.03 |
4.06 |
7.06 |
6.75 |
6.00 |
5.19 |
4.94 |
|
Flavour |
7.50 |
5.50 |
6.81 |
NR |
6.56 |
6.38 |
5.81 |
5.00 |
4.06 |
|
Texture |
5.00 |
5.03 |
5.34 |
NR |
5.44 |
5.56 |
6.38 |
7.13 |
7.09 |
|
Tenderness |
5.13 |
5.25 |
5.44 |
NR |
5.56 |
5.94 |
6.38 |
7.44 |
7.52 |
|
Juiciness |
5.06 |
5.13 |
5.25 |
NR |
5.58 |
5.69 |
6.44 |
7.19 |
5.13 |
|
Overall acceptance |
7.31 |
5.94 |
6.94 |
4.94 |
6.81 |
6.75 |
6.00 |
5.13 |
5.00 |
|
Means bearing different superscripts differ significantly (P<0.05) |
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Four day chilled buffalo meat had a significantly (p<0.05) lower flavour score than the frozen meat. The flavour scores were 5.5±0.26 and 6.81±0.21 in chiller and freezer respectively. A high flavour score in freezer may be attributed to a low pH compared to a high pH in chiller. In 7 day chilled meat the flavour score was not recorded since the meat was spoiled. Prolonged storage in freezer resulted decline in flavour scores. Flavour score of 6.56±0.20, 6.38 ±0.18, 5.81± 0.39, 5.00±0.20 and 4.06±0.06 were observed on 7 th, 14 th, 30 th , 60th and 75th days of frozen storage respectively in the present study. This decline in flavour scores in frozen storage was also reported by Ristic and Schon (1980).
On zero (0) day in the present study, the texture score was 5.00±0.16 in fresh buffalo meat (Table 2). 4 day stored buffalo meat in chiller (4±10C) and freezer (-10±10C) showed marked improvement in texture scores. The scores were 5.13±0.20 and 5.38±0.13 in chiller and freezer respectively. The results showed texture sores of 5.44±0.18, 5.56±0.18, 6.38±0.29, 7.13±0.18 and 7.19±0.10 in 7,14,30,60 and 75th days of frozen meat respectively. This increased score in frozen storage was also studied by Arief et al (1989). Freezing tenderized meat by splitting fibre and breaking or stretching connective tissue surrounding muscle fibres and fibre bundles (Hiner and Hankins 1951). Texture scores of 30 th and 60 th days of frozen meat showed a significant (P<0.05) variation.
On zero day in the present study, the tenderness scores for buffalo meat was 5.13±0.47 in fresh state (Table 2). 4 day stored buffalo meat showed an increased trend in tenderness scores. The scores were 5.25±0.19 and 5.44±0.24 in chilled and frozen meats respectively. The frozen meat had a significantly higher score than the chilled meat. An increased tenderness score in chilled meat was reported by Dushyanthan et al (1994). Spoilage was observed in 7th day chilled meat. The scores were not recorded since that meat couldn't be used for consumption. The results showed tenderness scores of 5.56±0.16, 5.63±0.32, 6.44±0.34, 7.36± 0.19 and 7.52±0.03 in 7,14,30,60 and 75 days of frozen buffalo meat. The results showed a significant (P<0.05) improvement in tenderness scores at 30 and 60 days of storage. Guenther et al (1960) indicated formation of intercellular and intracellular ice crystals during frozen condition indirectly contributed to tenderisation of meat.
On zero (0) day in the present study, the juiciness score was 5.06±0.38 for fresh buffalo meat (Table 2). On 4 days of storage the scores were 5.13±0.22 and 5.25±0.31 in chilled and frozen buffalo meat respectively. It was evident that though chilling and freezing improved the juiciness scores, freezing bettered chilling in the effort. The scores were 5.56±0.26, 5.69±0.22, 6.44±0.13, 7.19±0.10 and 7.13±0.08 on 7 th, 14 th , 30 th , 60 th and 75th days of frozen storage. Arief et al (1989) recorded an increased juiciness scores on 30 th and 60th days of frozen storage. Though there were marked drip losses in later days of frozen storage, it was not significant enough to reflect on the juiciness characteristic of the meat during sensory evaluation.
On zero (0) day in the present study, the overall acceptance score of buffalo meat was 7.31 ±0.22 (Table 2). The results showed an acceptability score of 5.94±0.24 and 6.94±0.21 in chiller and freezer respectively. In 7th day the overall acceptance score was observed as 4.94±0.06. This differed significantly (P< 0.05) with the frozen value on the same day. The gradual decline in scores recorded were 6.81±0.29, 6.25±0.30, 6±0.18, 5.13±0.27 and 5.00 on 7 th, 14 th, 30 th and 60 th , 75th days of storage respectively. Marriot et al (1980) and Selvaraj et al (1988) also observed this decreasing trend in acceptability of frozen meat.
Sixty days of frozen storage improved some of the sensory qualities of buffalo meat. But taking into account of the above all considerations, it may be concluded that a storage period up to 4 days in chiller (4 ±10C) and 30 days in freezer (-10 ±10C) could satisfactorily maintain the buffalo meat quality.
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Received 23 July 2005; Accepted 7 October 2005; Published 1 November 2005