H. W. Ockerman1 and Y. M. Sun
The Ohio State University Department of Animal Sciences
Reduction of nitrite from 150 to 75 ppm resulted in an increase in total plate count organisms but no change in the oxidation of the product. No difference was found between fresh garlic, garlic powder, or essential oil of garlic for oxidation values or total plate count microorganisms, but oil of garlic resulted in the lowest acceptability scores. There was no evidence that addition of garlic could be used to reduce the bacterial level in sausage.
Sausages are very common and popular processed meat products manufactured from lower-value trimmed meat to produce a higher-value product. Food additives are used to accomplish certain functions such as coloring, antimicrobial, antioxidative, preservation, improved nutrition, increased emulsification, and altered flavor. Garlic, which is available in three different forms (fresh, dehydrated, and extracted), is one of the most common spices which is frequently used in Chinese-style sausage. There are a lot of reports concerning the antibacterial and antioxidant effects of garlic on meat products (Juri-Haldeman et al., 1987; Al-Delaimy and Barakat, 1970; Dewit et al., 1978; Kourounakis and Rekka, 1991; Lin et al., 1991; El-Khateib and El-Rahman, 1987; Lois, et al., 1987; Ismaiel and Pierson, 1990). However, these effects have not been studied in Chinese-style sausage. Due to health concerns of some related to the reaction products of nitrite used in meat products and a desire to lower the level of nitrite, different forms of garlic were added to Chinese-style sausage to evaluate the flavor, color, antimicrobial, and antioxidant effects at two different nitrite levels (75 ppm and 150 ppm [normal]).
Boneless pork shoulders were trimmed (fat and lean trimmings separately) and ground through a 0.95 cm plate. Ground lean and fat were combined at a ratio of 4:1. Then, nitrite (75 or 150 ppm), salt (1.7%), seasoning (0.5% MSG, 8% sugar, 2% rice wine, 0.2% sodium polyphosphate) and spice (5% fresh garlic, 1.2% garlic powder, or 0.006% garlic essential oil) were added into the meat and thoroughly mixed. Farrell (1990) stated that "commercial oil of garlic, undiluted, has 200 times the strength of dehydrated garlic or 900 times the strength of fresh garlic." In this study, 5% of fresh garlic was chosen due to the results of the study of El-Khateib and El-Rahman (1987) who found that this quantity of garlic was more efficient at inhibiting bacteria than other treatments. And since 5% of fresh garlic has been reported to be equal to 0.006% undiluted commercial garlic oil and equal to 1.2% garlic powder, these levels were used as treatment levels in this research.
Seasoned meat was cured at 4ºC for one day for flavor and color formation and then stuffed into edible 2 cm diameter artificial collagen casings. Sausages were dried at 50 to 55ºC for 18 hours and then vacuum-packed in sterile bags and were stored at 4ºC.
| Figure 1. Experiment design. |
The following evaluations were performed on the sausage products – thiobarbituric acid (TBA), total anaerobic plate count (TPC), pH, and sensory panel test (Figure 1). This is a 2 X 4 (X 5 or X 7) factorial experiment in a randomized complete block design. All the data were analyzed by analysis of variance (ANOVA) and significant difference determined by F-test (SAS, 1985). The means of treatments were evaluated by the Duncan procedures in the Statistical Analysis System (SAS, 1985).
The TBA Analysis
There was no significant two- or three-way interaction in TBA values, and no significance was found when comparing to 75-ppm and 150-ppm-nitrite-added groups (Table 1). These latter results were unexpected since nitrite has been reported as a very effective antioxidant in meat products (Ockerman, 1986); however, 75 ppm of nitrite may be sufficient for this purpose in vacuum-packaged products. There was also no significant difference due to garlic treatments, and again, this was unexpected since garlic has been reported to be a modest antioxidant in sausage items (Farrell, 1990). The TBA values also did not increase during the 28 days of storage, probably also due to the vacuum packaging. All the sausage samples indicated that there was little oxidation occurring with TBA values ranging from 0.15 to 0.20 g/kg. A value of 1.0 g/kg is usually considered to be the beginning of noticeable oxidation (Ockerman, 1986).
Table 1. Main Effects of Nitrite, Different Garlic Treatments, and Time on TBA (Thiobarbituric Acid) Values, TPC (Total Plate Count) Numbers, and pH Values on Chinese-Style Sausage.1 |
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|---|---|---|---|---|---|---|---|---|---|---|---|
| Nitrite | Treatment | ||||||||||
| 75 ppm | 150 ppm | C | F | P | O | ||||||
| TBA | 0.18a | 0.18a | 0.17a | 0.20a | 0.20a | 0.17a | |||||
| TPC2 | 4.36a | 4.05b | 4.24a | 4.17a | 4.29a | 4.13a | |||||
| pH | 6.40b | 6.43a | 6.42b | 6.45a | 6.41b | 6.39c | |||||
| Storage in Days | |||||||||||
| 0 | 2 | 4 | 7 | 14 | 21 | 28 | |||||
| TBA | 0.20a | 0.20a | 0.18ab | 0.15b | 0.18ab | 0.15b | 0.20a | ||||
| TPC2 | 4.23a | 4.33a | 4.06a | 4.26a | 4.25a | 4.12a | 4.18a | ||||
| pH | 6.41cd | 6.43bc | 6.47a | 6.45ab | 6.39d | 6.39d | 6.38d | ||||
| 1 C=control
(no garlic), F=fresh garlic (5%), P=garlic powder (1.2%), O = Garlic essential
oil (0.006%). 2 TPC is expressed as CFU/g on a log10 basis. a,b,c Means with different superscript letters in the same row for nitrite or treatment or storage time are significantly different (P < 0.05). |
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Total Plate Count (TPC) Numbers
No two- or three-way interaction was found for TPC numbers, and the 75-ppm-nitrite-added group had significantly higher TPC values than the 150-ppm-nitrite-added group as would be expected due to the antimicrobial effect of nitrite. There was no significant difference found for different garlic treatments, and no difference found during storage at 4ºC, both of which were unexpected since reports (Jurdi-Haldeman et al., 1987) indicate that garlic has antimicrobial properties. However, the drying, nitrite, salt, wine, and vacuum packaging combination may help to inhibit bacteria growth. All the TPC numbers of the sausage samples were less than 106 CFU/g (an index number of spoilage [Wang, 1992]) and would suggest that microbial growth did not cause spoilage of these samples. Since TPC numbers decreased with nitrite level and were not different due to treatment, this would not suggest reducing the nitrite level in this product simply by adding garlic.
The pH Value
There was no two- or three-way interaction for pH values, and the group with 150-ppm nitrite had significantly higher pH values than that of the 75-ppm-nitrite-added group (Table 1). This was probably due to the greater growth of lactic acid bacteria in the 75-ppm nitrite treatment (Jay, 1991). The fresh garlic treatment resulted in higher pH values than all other treatments, with the garlic-essential-oil-added treatments having the lowest values. The pH values of all treatments showed no consistent change with storage time.
Sensory Evaluation
There was no two- or three-way interaction found among any sensory evaluation items, and no differences were found between 150-ppm and 75-ppm-nitrite-added groups for any sensory evaluations (Table 2). This is not as would be expected, since nitrite has been reported to affect cured color and flavor, but in a dried, highly spiced product, 75 ppm of nitrite may be sufficient. No differences were found for color, juiciness, texture, or oxidation for the different garlic treatments. Fresh garlic treatment had a higher garlic flavor value than that of garlic powder and garlic essential oil treatments, and all the garlic treatments had higher garlic flavor than the control which would be expected. However, the garlic flavor for the garlic treatments should have been the same if the flavor ratio given in the literature was accurate (Farrell, 1990) or if the garlic used in this research was of average potency. The garlic-essential-oil treatment had lower overall acceptability values than the other three treatments. This was probably due to the oil extraction, where only a portion of the flavor profile of the fresh garlic was extracted, and this flavor might be unfamiliar or not as acceptable to some panelists. Also, garlic oil had a lower pH value than the other additives, which might have given a bitter flavor. Garlic flavor strength maintained a fairly stable level during the storage period. However, the scores of all sensory items decreased slightly as storage time increased (Table 2) as would be expected.
Table 2. Main Effects of Nitrite, Different Garlic Treatments, and Time on Sensory Properties of Chinese-Style Sausage.1 |
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|---|---|---|---|---|---|---|
| Nitrite | Treatment | |||||
| 75 ppm | 150 ppm | C | F | F | O | |
| Red Color2 | 5.49a | 5.50a | 5.50a | 5.34a | 5.44a | 5.51a |
| Garlic flavor3 | 4.65a | 4.76a | 3.41c | 6.77a | 4.45b | 4.19b |
| Juiciness4 | 5.72a | 5.53a | 5.54a | 5.78a | 5.60a | 5.59a |
| Texture5 | 5.59a | 5.46a | 5.43a | 5.60a | 5.57a | 5.49a |
| Oxidation6 | 6.28a | 6.36a | 6.21a | 6.55a | 6.29a | 6.24a |
| Overall7 | 6.05a | 5.92a | 6.00a | 6.08a | 6.18a | 5.69b |
| Storage Time in Days | ||||||
| 0 | 7 | 14 | 21 | 28 | ||
| Red Color2 | 5.97a | 6.00a | 5.25b | 5.00b | 5.24b | |
| Garlic flavor3 | 5.26a | 4.73b | 4.52bc | 4.10c | 4.90ab | |
| Juiciness4 | 5.83a | 6.08a | 5.84a | 5.23b | 5.14b | |
| Texture5 | 5.78b | 6.10a | 5.71b | 5.04c | 4.98c | |
| Oxidation6 | 6.83ab | 6.95a | 6.37bc | 6.13c | 5.32d | |
| Overall7 | 6.26ab | 6.56a | 6.05b | 5.65c | 5.42c | |
| 1 C=control
(no garlic), F=fresh garlic (5%), P=garlic powder (1.2%), O=Garlic essential
oil (0.006%). 2 Red color: 1=extremely dark, 9=extremely light. 3 Garlic flavor: 1=extremely bland, 9=extremely garlic flavored. 4 Juiciness: 1=extremely dry, 9=extremely juicy. 5 Mouth fell texture: 1=extremely fine, 9=extremely coarse. 6 Oxidation: 1= extremely rancid flavor, 9=extremely nonrancid flavor. 7 Overall acceptability: 1=very low overall acceptance,9=very high overall acceptance. a,b,c,d Means with different superscript letters in the same row for nitrite, treatment, or time are significantly different (P < 0.05) |
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No difference was found in yield, protein, and fat contents of both 75-ppm and 150-ppm nitrite groups. The utilization of 75 ppm of nitrite resulted in lower pH but higher TPC numbers than those of the 150 ppm nitrite-added group, but no significant difference in TBA values and sensory evaluation were found. The fresh garlic treatment showed higher pH and more intensive garlic flavor than the other treatments. No difference was found among all garlic treatments in TBA values and TPC numbers. No difference was found for all sensory evaluations due to garlic treatments except for the garlic-essential-oil treatment, which had a lower overall acceptability.
The pH value and sensory evaluation scores decreased with time, but no change was found in TBA values and TPC numbers during storage time.
Since bacteria numbers increased with lower nitrite levels and no improvement was found in TBA values or bacteria numbers with adding garlic, there is no evidence that adding garlic to Chinese-style sausage under conditions used in this research should be utilized as a reason to decrease the nitrite level.
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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