H. W. Ockerman1 and C. T. Li
The Ohio State University Department of Animal Sciences
A modified more rapid and less expensive process was developed to produce a palatable and tender dehydrated pork item. This cooked product will keep without refrigeration and will not drastically change with room-temperature storage. Due to the low moisture content, there were few microorganisms and mold growth, and this aided in extending the shelf life. A low-fat version was produced along with a more flavorful, higher fat version. This product could be used as a snack item or incorporated into other food items to add flavor and increase the protein content.
Meat is well known as an excellent protein and energy source for our daily diets and, after digestion, provides excellent nutrition. However, meat can be very perishable due to its high moisture and protein contents, which may be utilized by microorganisms. The principle of extending the shelf life of meat products is to produce an unfavorable environment for microorganisms to grow. Among many preservative methods, dehydration was probably one of the earliest and most effective methods that has been developed.
In this project, a new type of oriental-style dehydrated meat product-meat floss, also called shredded pork (Chang and Huang, 1991), which possesses the advantages of long shelf life, desirable taste, safe ingredients, and low cost was evaluated. Of all the oriental dehydrated meat products, shredded pork is probably the most important fresh meat substitute in areas of China where refrigeration is not available. Its amazing long shelf life at room-temperature storage and good nutritional values have also brought great convenience to travelers and campers. It may also serve as a protein sustenance for the military, because it also has the advantages of being lightweight, easy-to-pack, and ready-to-eat. It can also serve as a snack or combine with other foods as part of the daily diet for the general population.
In this project, a less expensive meat source, the shoulder instead of traditionally used ham, and a new less labor-extensive processing technique with variable fat levels (2 and 12%) were compared with the time and labor-intensive traditional processing method. Since little is known about this oriental product, chemical analysis (fat, protein, and moisture), biochemical properties (pH and thiobarbituric acid [TBA]), microbiological assays (total plate count and mold growth), and sensory evaluation (color, meaty flavor, rancidity, texture, and overall acceptance) were conducted to investigate the potentials of this dehydrated meat product.
The experiment was designed as a 2 (fresh and frozen) x 2 (traditional and modified) x 2 (2% and 12% lard) factorial. Boneless, skinless pork shoulders were obtained from a local supermarket in Columbus, Ohio. Eight approximately 5.4 pounds (2.45 kg) of boneless, skinless pork shoulders were prepared for trimming. All visible fat and connective tissue were carefully removed from the surface and internal tissue. The trimmed lean pork was then prepared for either the traditional or the modified process. The procedure for traditional method included moist-cooking (100°C, 3-1/3 hours), physical fiber separation, moisture evaporation (100°C, 55 minutes), and stir-frying (60 to 65 strokes/minute for 55 minutes). The modified procedure was autoclave (121°C, 15 psi, 30 minutes), physical fiber separation, moisture evaporation (100°C, 55 minutes), stir-frying (60 to 65 strokes/minute for 29 minutes) combined with 15 minutes of hot-air drying, and then convection-oven dried (93.3°C, 45 minutes). All samples were vacuum-packaged and stored in a dark room at room temperature (27 ± 2°C).
Cooking yield, moisture, crude fat, and crude protein contents were established at week 0. Since the pH, TBA, and sensory evaluation (color, meaty flavor, rancidity, texture, and overall acceptance), total plate count, and mold count were measured at week 0, 1, 3, 5, and 7 of storage, the storage time also became an additional independent variable (the fourth main effect).
The results of all measurements are summarized in Table 1. For cooking yield and chemical analysis, there was no significant three- or two-way interaction between the main effects (P < 0.05). The results of cooking yield (%) are shown in Table 1. The 2% lard addition treatments (44.81%) are significantly lower than those with 12% lard addition treatments (54.68%) at the 0.05 level. This suggests that the level of lard addition plays an essential role in the cooking yield.
Table 1. Statistical Significance (P<0.05) of Main Effects for Cooking Yield, Chemical Analysis, pH, Thiobarbituric Acid (TBA) Values, Sensory Evaluation, and Microbial. |
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|---|---|---|---|---|---|---|---|---|---|---|---|
| Treatment (Main Effects) |
Raw Material Temperature |
Cooking Method |
Lard Addition |
Storage Time |
|||||||
| Fresh (4 ± 2°C) |
Frozen (-18 ± 2°C) |
Traditional | Modified | 2% | 12% | Week | |||||
| 0 | 1 | 3 | 5 | 7 | |||||||
| Cooking Yield1,% | 49.94a | 49.54a | 49.39a | 50.09a | 44.81a | 54.68b | NA5 | ||||
| Moisture1, % | 4.37a | 4.33a | 4.35a | 4.35a | 5.23a | 3.47b | NA | ||||
| Crude Fat1, % | 24.15a | 24.07a | 24.15a | 24.06a | 16.89a | 31.33b | NA | ||||
|
Crude Protein1, % |
38.71a | 38.28a | 38.50a | 38.49a | 42.90a | 34.09b | NA | ||||
| pH2 | -- | -- | -- | -- | -- | -- | 6.33a | 6.33a | 6.36a | 6.34a | 6.33a |
| TBA2,µg/g | -- | -- | -- | -- | -- | -- | 0.45a | 0.53b | 0.54bc | 0.56c | 0.63d |
| Color3 | -- | -- | -- | -- | -- | -- | 4.55a | 4.39a | 4.29a | 4.48a | 4.44a |
| Meaty Flavor3 | 5.51a | 5.50a | 5.46a | 5.55a | 5.32a | 5.70b | 5.48a | 5.52a | 5.37a | 5.51a | 5.86b |
| Rancidity3 | 3.04a | 3.18a | 3.11a | 3.10a | 3.05a | 3.16a | 2.92a | 3.01a | 3.04ab | 3.23ab | 3.34b |
| Texture3 | -- | -- | -- | -- | -- | -- | 5.70a | 5.73a | 5.60a | 5.72a | 5.64a |
| Overall Acceptance3 | 5.86a | 6.02a | 5.82a | 6.07b | 5.88a | 6.00a | 5.88a | 6.02a | 5.93a | 5.87a | 6.00a |
| TPC4 | -- | -- | -- | -- | -- | -- | 2.18a | 2.04a | 2.08a | 2.12a | 2.01a |
| Mold Count4 | -- | -- | -- | -- | -- | -- | 0.00a | 1.47b | 1.27b | 0.81c | 0.64c |
|
a,b,c, and d: Means with different superscripts in the
same attribute row indicate the significant difference at the 0.05 level
(P < 0.05) – indicates three- or two-way interactions were involved;
therefore, they are not applicable in this table. N/A indicates
the main factor (storage time) is not applicable in three-way (Temperature
x Cooking Method x Lard Addition) model. |
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For moisture content analysis, the treatments with 12% of lard addition had a lower percentage of moisture content (3.47%) than those with 2% of lard addition (5.23%). This was caused by the increased level of lard (fat), which will alter the proportions of other components (moisture, protein, and fat) in the meat products. In addition, it indicates that temperature of raw material and cooking method have no significant influence on the moisture content of the meat floss. The same trends are shown in crude fat and crude protein (Table 1). The pH values show little or no changes during seven weeks of room temperature (27 ± 2°C) storage. It supports the hypothesis that meat floss is a very shelf-stable product.
On the other hand, the data indicates that there are a few statistical differences between some of the three- or two-way treatments. However, these influences are very minor. The TBA value has been commonly considered as an index of lipid rancidity. Table 1 indicates that the TBA values slightly increased during storage (0.45 to 0.63 µg/g). The oxygen in the vacuum-packed bags could have come from the slow rate of natural release from the internal air cells of the meat floss. As Ockerman (1985) indicated, a TBA number of 1.0 is considered as the threshold level for rancidity in pork by some processors. The results also suggest that a longer than seven weeks of product shelf life at room temperature (27 ± 2°C) storage may be expected. Color scores for all treatments were very consistent during the seven weeks of storage.
Results indicate that the level of lard addition is the main effect that influences the meaty flavor (Table 1). The results were as expected, since fat is the main factor responsible for the volatile flavor compounds of meat products. Due to more macromolecules in meat products being degraded into smaller ones during storage, the trend of a slight increase in meaty flavor was noted. The slight increase of the rancidity score during the seven weeks of storage may be caused by the same reason described for the TBA values. There was no significant difference at the 0.05 level in the texture scores during storage. The panel’s response to texture was "somewhat crispy."
Overall acceptance indicates that three main factors, raw material temperature, lard addition, and storage time had no significant effect on the evaluation. However, a fourth main effect, the cooking method, showed that panels preferred the modified method (6.00) over the traditional method (5.88), despite the fact there was only a slight difference between these two techniques. For microbial assays, the log10 TPC numbers were very low (2.01 to 2.18), which indicated that the numbers of microbial flora were lower than 200/g, even after seven weeks. The results of log10 colony forming units (CFU) mold count were very similar to the results in TPC; both indicated extremely low microbial growth. It indicates that the Log10 CFU/g for storage-time treatments were very low (0.00 to 1.47), which means that the numbers of mold colonies were lower than 30/g during the entire seven weeks of storage. It also indicates the unfavorable growing environment (low moisture) is not suitable for bacteria or mold growth.
The low level of microbial growth during storage clearly indicated the long non-refrigerated shelf life. The sensory evaluation showed the potential marketing of this product. Also this product should be economical in cost since the raw materials wree inexpensive, and lower-grade carcasses can be utilized; for example, even PSE meat or two-tone muscle is acceptable, It is expected that shredded pork can be a popular, long-term, commercial meat snack or food additive. In the past, most oriental products were handmade; therefore, they were always very time and labor-consuming. With the designed modified process (modified autoclaving method) and the rapid advance of automation, meat floss can become a new product. The modified method saved approximately one-half of the original processingtime (five hours or longer). In addition, the difference between other factors (raw material temperature and lard addition) didn't seem to have much influence on most sensory attributes; therefore, it suggests that the manufacture of meat floss is very flexible in relation to raw material and ingredients utilized. With today's advanced machinery techniques, it solve the equipment problem and make the commercialized mass-production of the meat floww possible in the future.
Chang, S.F. and Huang, T.C. 1991. Meat Sci. 30:303-325
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Lawrie, R.A. 1991. The storage and preservation of meat. pp. 152-172. In: Meat Science. Pergamon Press, New York.
Ockerman, H.W. 1985. Quality Control of Post-Mortem Muscle Tissue. Vol. 1. pp. 51.0-51.2 and 70.1-80.1. Department os Animal Sciences, The Ohio State University and the Ohio Agricultural Research and Development Center, Columbus and Wooster, Ohio, USA.
1 For more information, contact at: The Ohio State University 15 Animal Science, 2029 Fyffe Road, Columbus, OH 43210, (614) 292-4317, Fax (614) 292-2929; email:ockerman.2@osu.edu