الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
 |  | from | 150 |  |  |
| | | from | 150 | | |
Abstract
Beef is a good source of high nutritional values, contains high-quality proteins and fats, in addition to many essential minerals and vitamins of importance to human health.
Imported frozen meathave become accepted and consumed all over world, as it low cost and have high nutritive value. Also the meat processing industries reliant on them.
The present study was carried out to in two parts:
1- Survey part: evaluate the nutritive value, physical and chemical quality of imported frozen beef meat and compare with local beef in Assuit city.
2- Experimental part: evaluate the effect of freezing storage at (-11ᵒc and -18ᵒc) on meat quality of local beef during the shelf life.
In survey part:Total number of 125 imported frozen meat (Brazilian, Indian, New Zealandand Australian) and local beef (25 for each type) were randomly collected from different butcher’s shops and markets in Assuit city.
The sampleswere inspected for physical (color, odor, shear force, drip loss, and WHC). In addition the samples were analyzed for proximate chemical composition: (moisture, protein, fat, ash carbohydrate, calorie value), mineral content (iron, zinc and copper) and chemical quality: (PH, TBA, and TVN) quality.
The obtained mean values of color score in Brazilian, Indian, New Zealand, Australian and local meat were 6.14±0.64, 5.80±0.89, 5.71±1.08, 5.43±0.77 and 8.14±0.66, respectively. The color scores of local fresh meats were significantly higher (p ˂ 0.05) in comparison with imported frozen meats.While that of odor score, were5.97±0.63,5.77±0.86,5.90±0.88, 5.67±0.66 and 7.91±0.71, respectively. Local fresh meatshad significantly higher odor scores (p˂ 0.05) compared to imported frozen meats. There was no significant difference between imported meats.
The shear force mean value were 5.45±1.04, 7.76 ± 1.26, 5.66±1.01, 5.00 ± 0.66 and 6.40 ±0.67 kgf/cm3, respectively. Indian meats showed significantly higher (p˂0.05) shear force compared with Brazilian, Indian, New Zealand, and Australian meats. However, no difference (p˃ 0.05) were found between Brazilian, New Zealand, and Australian meats. While of pH were 5.73±0.18, 5.82±0.24, 5.97±0.16, 5.96±0.25 and 5.70±0.10, respectively for Brazilian, Indian, New Zealand, Australian and local meats. No significant differences were found between the pH values of the studied meat items.
The mean values of WHC value were 38.51±3.48, 39.49±2.11, 42.18±2.47, 37.82±6.43 and 39.86±0.87, respectively. WHC in New Zealand meats were significantly higher (p˂0.05) in comparison with Brazilian, Indian and Australian meats. However, no significant difference was recorded between WHC of local meat and other studied imported meat items. While of drip loss value were 11.08±1.38, 12.58±1.64, 8.97±1.46, 8.24±1.49, 0.00±0.00, respectively in Brazilian, Indian, New Zealand, Australian and local meat.There was significant difference between local and imported meats. No significant difference (p ˃ 0.05) was found between the drip loss values of different imported frozen meat items.
The mean values of TVN were 15.34±1.25, 17.50±1.53, 14.37±1.73, and 16.52±1.32 and 11.63±1.54 mg/100 gm, respectively.Local fresh meats showed significantly lower TVN value in comparison with imported meats and there was no significant difference between the imported meats. And ofTBA values were 0.23± 0.10, 0.70±0.24, 0.49±0.12, 0.41±0.11 and 0.17± 0.08 mg/kg, respectively for Brazilian, Indian, New Zealand, Australian and local meat.Brazilian and local fresh meats showed significantly less (p˂0.05) TBA compared to Indian, New Zealand and Australian meats, Indian meats recorded the significantly (p˂0.05) higher TBA content compared to other meat items.
Furthermore, the achieved results of moisture were 75.36 ±1.37, 75.01± 1.84, 76.72±1.11, 77.38±1.4700 and 74.12±0.92%, respectively.Australian meats showed the highly significant (p˂ 0.05) moisture content compared to the other studied meat items, except with New Zealand meats the difference was insignificant (p˃ 0.05).While, the mean value of protein were 19.87±0.98, 20.34±0.83, 19.12±0.61, 18.90±0.80 and 20.70±0.85%, respectively for Brazilian, Indian, New Zealand, Australian and local meats. There was no significant difference of protein content between the various studied meat items.
The mean values of fat were 3.16±0.96, 3.01±0.85, 2.83± 0.65, 2.38± 0.89 and 4.01±0.42%, respectively, for Brazilian, Indian, New Zealand, Australian and local meats. Local meats showed significantly (p˂0.05) higher level of fat in comparison with imported frozen meats, while, Australian meats showed significantly less fat content.
The mean values of ash were 1.07±0.14, 1.15± 0.25, 1.11±0.15, 1.08±0.14 and 0.99±0.09%. No significant differences were found between ash content of various studied meat items, and of, carbohydrate, the mean values were 0.54±0.26, 0.53±0.32, 0.22±0.11, 0.27±0.18 and 0.18±0.11%, respectively for Brazilian, Indian, New Zealand, Australian and local meats. Brazilian and Indian imported frozen meats showed the significantly (p˂ 0.05) higher carbohydrate content. No significant differences (p˃ 0.05) were found between New Zealand, Australian and local meats.
The detected calorie value for Brazilian, Indian, New Zealand, Australian and local meat were 110.07±9.23, 110.62 ± 10.44, 102.83 ± 7.62, 98.09 ± 10.12 and 119.58 ± 4.88 kcal/100gm, respectively. Local meats showed significantly (p ˂ 0.05) higher calorie value in comparison with imported frozen meats. New Zealand and Australian meats contain significantly less calorie values than Brazilian and Indian meats.
The recorded mean valuesof zinc were 5.59±0.64, 6.29±1.10, 4.36±0.59, 4.45± 1.09, 7.61±1.09, of iron were 5.28±1.00, 4.98± 1.02, 3.06±0.51, 3.24± 0.49 and 5.72± 0.77; while of copper were 0.11±0.02, 0.15± 0.20, 0.21± 0.21, 0.23±0.04 and 0.19±0.04 mg/100gm, respectively in Brazilian, Indian, New Zealand, Australian and local meats. There was significant difference in zinc level between different meat items, local meat showed significantly higher Zn level than imported frozen meat, while there was no significant difference in iron and copper level between meat items
In experimental part: bulk of fresh meat taken from the hind quarter of the beef carcass, were bought from butcher shop and used for studying the effect of freezing storage on the meat quality during shelf life. The bulk were divided into smaller portions 250 gm each and made in two groups, one stored at -11ᵒc and the other stored at -18ᵒc.The stored samples were analyzed at interval of 2 months for physical and chemical quality, as well as proximate composition and some trace elements.
The results of stored samples were:
The obtained results of color score of fresh beef was 8.7 at zero day, after freezing the color score of beef stored at-11°C was 8.3 at 2 months, 7.6 at 4 mths, 7.1 at 6 mths, 6.6 at 8 mths, 5.6 at 10 months (end of shelf life).For beef stored at -18 °C, the score was 8.6 at 2 months, 8.5 at 4 mths, 8.3 at 6 mths, 8.3 at 8 mths, 8.0 at 10 mths, 7.6 at 12 mth, 7.6 at 13 mth, 7.5 at 14 mth, 7.4 at15 mth, and 6.5 at 16 mth (end of shelf life). The decrease in color scores were more pronounced at -11 °C than at -18 °C.
Odor score of fresh beef(day zero) was 8.6, after freezing storage the score at -11°C was 8.5, 8.1, 7.6, 7.4 and 6.3 in 2, 4, 6, 8 and 10 (end of shelf life), respectively.As well, the odor score of beef stored at -18 °C was 8.5, 8.3, 8.2, 7.8, 7.6, 7.5, 7.4, 7.4, 7.4 and 7.3 in 2, 4, 6, 8, 10, 12, 13, 14, 15 and 16 month, respectively. The decline rate in odor score at -11°C was higher than at -18°C.
The achieved results of shear force (kgf/cm3) of fresh beef was 6.3, after freezing at -11°C, the shear force in 2, 4, 6, 8 and 10 months freezing was6.1, 5.9, 5.9, 5.7 and5.6, respectively. While at -18°C for 2, 4, 6, 8, 10, 12, 13, 14, 15 and16 months of storage, the shear force was 6.0, 5.8, 5.6,5.5, 5.2, 5.0, 5.0, 4.9, 4.8 and4.8, respectively.
PH value of fresh beef was 5.6 and gradually increased with frozen storage at -11°C to 5.7 in 2 mths, 5.8 in 4 mths, 5.9 in 6 mths,5.9 in 8 mths, and6.0 in 10 mths. The pH of beef stored at -18°C was 5.6, 5.7, 5.7, 5.8, 5.9, 5.9, 6.0, 6.1, 6.2 and 6.2 in 2, 4, 6, 8, 10, 12, 13, 14, 15 and16 months of storage.
The obtained results of WHC (%) was 41.1 for fresh beef and after freeze storage at-11°C was 40.5, 39.2, 38.1, 31.4 and 30.5 in 2, 4, 6, 8 and 10, respectively (end of shelf life).During storage at -18°C, the WHC decreased to 41.0 , 40.3, 39.0, 37.3, 36.4, 35.6, 32.1, 30.5, 28.7 and 26.6 in 2, 4, 6, 8, 10, 12, 13, 14, 15 and 16 month of storage, respectively.
The drip loss (%) of fresh beef was 0.0that increased with frozen storage tobe 4.1, 6.4, 9.1, 11.3 and 15.4 in 2, 4, 6, 8 and 10 months at -11°C, while at -18°C, it increased to 2.3, 3.5, 5.7, 6.7, 8.5, 10.2, 10.6, 11.7, 12.2 and 13.4 in 2, 4, 6, 8, 10, 12, 13, 14, 15 and 16 month, respectively.
TVN (mg/100gm) of fresh beef was 12.4 (day zero).After freezing storage at -11°C the value reached 12.8 in 2 mths, 15.5 in 4 mths, 16.8 in 6 mths, 18.4 in 8 mths and 20.0 in 10 months. For beef stored at -18°C, thevalue reached12.6 in 2 mths, 14.6 in 4 mths, 15.3 in 6 mths, 16.5 in 8 mths, 16.8 in 10 mths, 16.8 in 12 mths, 17.0 in 13 mths, 18.6 in 14 mths, 19.4 in 15 mths and 19.8 in 16 mths (end of shelf life).
The achieved results of TBA (mg/kg) showed that the value in fresh beef was 0.09. As the meat freeze stored at -11°C, TBA was 0.23 in 2 mths, 0.41 in 4 mths, 0.64 in 6 mths, 0.71 in 8 mths, and 0.80 in 10 mths (end of shelf life). However, at -18°CTBA was 0.11, 0.33, 0.40, 0.45, 0.50, 0.60, 0.66, 0.67, 0.85 and 0.90 in 2, 4, 6, 8, 10, 12, 13, 14, 15 and 16 months of storage, respectively.
The moisture % of fresh beef was 74.3, after freezing the moisture value of stored beef at -11°C was 74.2 in 2 mths, 73.5 in 4 mths, 73.2 in 6 mths, 72.5 in 8 mths, 72.3 in 10 months (end of shelf life). Regarding beef stored at -18°C,the moisture %was 74.3 in 2 mths, 74.0 in 4 mths, 73.5 in 6 mths, 73.4 in 8 mths, 73.2 in 10 mths, 73.1 in 12 mths, 73.1 in 13 mths, 72.8 in 14 mths, 72.4 in 15 mths, 71.9 in 16 month(end of shelf life).
The protein % of fresh beef (day zero) was 21.2. with storage at -11°C, the percentage was 21.0, 20.8, 19.1, 18.4 and 18.1, respectively in 2, 4, 6, 8 and 10 months (end of shelf life), and at -18°Cit was21.2, 21.0, 20.6, 20.0, 19.5, 18.8, 18.3, 18.1,17.6and 17.4 in 2, 4, 6, 8, 10, 12, 13, 14, 15 and 16 month of storage (end of shelf life).
The fat % of fresh beef was 3.1, after freezing at -11°Cthe fat value of stored beef was 3.1, 2.9, 2.5, 2.3 and 2.1, respectively in 2, 4, 6, 8 and 10 months of storage (end of shelf life). As for beef stored at -18°C the fat % was 3.0, 3.0, 2.9, 2.6, 2.6, 2.6, 2.3, 2.2, 1.9 and 1.5, respectively in 2, 4, 6, 8, 10, 12, 13, 14, 15 and 16 month of storage.
The ash value % was 1.30 at zero day (fresh beef), and after freezingfor 2, 4, 6, 8 and 10 monthsat –11°C, the ash value was 1.10, 1.07, 1.03, 0.99 and0.99, respectively. Meanwhile, after storage at -18°C for 2, 4, 6, 8, 10, 12, 13, 14, 15 and16 month, the value was 1.30, 1.20, 1.10, 1.10, 1.09, 1.07, 1.06, 1.03, 1.00 and 0.99, respectively.
The energy value (kcal/100gm) at zero day was 112.7, after freezing for 2, 4, 6, 8 and 10 months at -11°C, the value was 111.9, 109.3, 98.9, 94.3 and 91.3, respectively (end of shelf life).With storage at -18°C for 2, 4, 6, 8, 10, 12, 13, 14, 15 and 16 month, the value was 111.8, 111.0, 108.5, 103.4, 101.4, 98.6, 93.9, 92.2, 87.5 and 83.1, respectively (end of shelf life).
As for the achieved results of minerals, the value of iron was 7.3mg/100gm in fresh beef. After freezing for 2, 4, 6, 8 and 10 months (end of shelf life) at -11°C, the value was6.0, 5.7, 5.4, 4.7 and 4.2 mg/100gm, respectively. As well, after storage at -18°C for 2, 4, 6, 8, 10, 12, 13, 14, 15 and 16 month, the iron value was 7.1, 6.5, 6.0, 5.8, 5.6, 5.5, 5.3, 5.1, 4.9 and 4.5, respectively.
The zinc level (mg/100gm) was 8.6 at zero day (fresh beef) and the level in beef stored at -11°Cwas 8.2, 7.6, 7.1, 6.6 and 6.5, respectively after 2, 4, 6, 8 and 10 months of storage. The level in beef stored at -18°C after 2, 4, 6, 8, 10, 12, 13, 14, 15 and 16 month (end of shelf life) was 8.6, 8.3, 8.1, 7.2, 7.1, 7.0, 6.9, 6.3, 6.1 and 5.9, respectively.
The copper level (mg/100gm) of fresh beef was 0.22; after storage at -11°C, it was 0.21, 0.19, 0.19, 0.16 and 0.12, respectivelyin 2, 4, 6, 8 and 10 months. With storage at -18°C the copper level was0.22, 0.21, 0.21, 0.18, 0.17, 0.17, 0.15, 0.11, 0.09 and 0.08, respectively in 2, 4, 6, 8, 10, 12, 13, 14, 15 and 16 months of storage (end of shelf life).
from the obtained results, the beef stored at -11°C become unacceptable after 10 months of storage, while that stored at -18°C become unacceptable after 16 months. The change in physicochemical and chemical composition parameters were more rapid at -11°C than at -18°C.