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Effect of substituting pork backfat with rind on quality characteristics of pork sausage
Meat Science 58 (2001) 409–412 www.elsevier.com/locate/meatsci
Effect of substituting pork backfat with rind on quality characteristics of pork sausage S. S. Abiola *, S. W. Adegbaju Department of Animal Production and Health, University of Agriculture, PMB 2240, Abeokuta, Ogun State, Nigeria Received 1 February 2000; received in revised form 22 January 2001; accepted 22 January 2001
Abstract A study was conducted in which pork backfat in pork sausage was replaced with rind at 0, 33, 66 and 100% levels. The high moisture and high protein content of rind consequently influenced the moisture and protein content of the final products. The fat level decreased with increase in the level of rind in the sausage. The lowest fat content of 7.99% was recorded on batch 4 sausage with 100% rind replacement level. Replacement of pork backfat with rind decreased refrigeration and cooking weight losses. The values obtained for sensory properties decreased with increase in the level of rind in the sausage. Up to 66% pork backfat can be replaced with rind in pork sausage without adverse effect on processing yield. # 2001 Elsevier Science Ltd. All rights reserved. Keywords: Substitution; Pork backfat; Rind; Characteristics; Pork sausage
1. Introduction Fat is an important constituent of processed meat products because it affects tenderness and juiciness. A high fat content is traditionally associated with succulence and flavour (Lister, 1996). However, the composition of fat in the human diet is becoming increasingly important because of apparent relationship between the amount and type of fat consumed and the incidence of coronary heart disease. Briggs and Schweigert (1990) indicated that pork backfat used in fermented sausage has about 40% saturated fatty acids. In the study of dietary fatty acids, the advantages of mono-unsaturated fatty acids over saturated and polyunsaturated fatty acids was reported (Mattson & Grundy, 1985). To decrease caloric density and to lower the intake of total dietary fat, saturated fatty acids and cholesterol, attempts have been made to replace fat with non-meat ingredients such as soy proteins (Sofos & Allen, 1977), vegetable oils (Paneras & Bloukas, 1994) added water (Claus, Hunt, & Kastner, 1990; Park, Rhee, & Ziprin, 1990), olive oil (Bloukas, Paneras, &
* Corresponding author. Tel.: +234-39-200190, ext. 177; fax: +234-39-234650.
Fournitzis, 1997) and carbohydrates (Yang, Trout, & Barry, 1995) without adverse effects on processing yield. Osburn, Mandigo, and Eskridge (1997) utilised pork skin connective gels satisfactorily in reduced-fat bologna. Pork skin was also used as raw materials for meat products in other studies (Puolanne & Ruusunen, 1981; Satterlee & Zachariah, 1973). This study investigated the effect of substituting pork backfat with rind on chemical, storage and sensory properties of pork sausage.
2. Materials and methods The thigh muscle and backfat obtained from an adult Large White boar slaughtered on the Teaching and Research Farm of University of Agriculture, Abeokuta, Ogun State, Nigeria were used for the study. The meat and fat were run separately through a 5-mm plate in a Kenwood machine and later frozen till the second day. Pork skin removed from the loin of the slaughtered pig was soaked in distilled water overnight and later used for the preparation of rind. Backfat on the skin was trimmed before and after scalding. Scalding in hot water at 61 C lasted for 5 min to ensure proper removal of pig hair from the follicle. The de-fatted skin was minced
0309-1740/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved. PII: S0309-1740(01)00043-2
410
S.S. Abiola, S.W. Adegbaju / Meat Science 58 (2001) 409–412 Table 1 Composition (%) of pork sausages Ingredients
Lean pork Pork backfat Pork rind Wheat flour Water Ascorbic acid Seasoning Total
Batches 1 (0%)
2 (33%)
3 (66%)
4 (100%)
55.56 12.33 – 15.11 15.11 0.05 1.84
55.56 8.26 4.07 15.11 15.11 0.05 1.84
55.56 4.19 8.14 15.11 15.11 0.05 1.84
55.56 – 12.33 15.11 15.11 0.05 1.84
100.00
100.00
100.00
100.00
Table 2 Proximate composition of pork rind Parameters
% Composition
Moisture Ash Fat Protein
40.92 1.82 28.69 27.01
Fig. 1. Flow diagram of sausage preparation.
with the Kenwood machine and later used as cooked minced rind. Proximate analysis of the rind was determined according to the method of AOAC (1990). Four batches of pork sausage (5 kg/batch) were prepared in which rind replaced pork backfat at 0, 33, 66 and 100% levels. Equal amounts of seasoning, water and wheat flour were added to each batch of pork sausage. Ingredient composition of the sausages is presented in Table 1 while the flow diagram of sausage preparation is shown in Fig. 1. Samples of the pork sausage from each batch were stuffed separately into pig casing (35 mm diameter) and refrigerated at 2 C for 24 h while some samples were cooked in water bath at 80 C for 15 min. Treatment in both cases was replicated three times and the study was repeated twice. Refrigeration loss was based on pre- and post-refrigeration weight of samples while cooking loss was the difference between fresh and cooked weights. Taste panel sensory evaluation of cooked samples was performed by 10 trained panelists. Parameters monitored were colour, flavour, juiciness, tenderness and acceptability. Each panelist was asked to rinse his mouth between each sample tested to avoid carry over effect. The evaluators scored each sample on a 7-point scale (1=unacceptable; 7=excellent). Data collected were subjected to analysis of variance while means were compared using the Duncan’s New Multiple Range Test (Steel & Torrie, 1980). Model used was (Harvey, 1990): Yij ¼ þ ai ¼ eij
where: Yij=dependent variable; =population constant; ai=effect due to the replacement of fat with rind (i=1,2,3 and 4); and eij=residual error with zero mean and variance 2.
3. Results and discussion The results of chemical composition of pork rind are presented in Table 2. Moisture content of pork rind was 40.92% while that of ash was 1.82%. Osburn et al. (1997) obtained 44.24% moisture content for raw pork skin connective tissue. The value obtained for the fat content of rind in the present study was 28.69% while that of protein was 27.01%. Osburn et al. (1997) reported values of 28.29% for fat and 26.47% for protein of raw pork skin connective tissue. In the manufacture of sausage with enzyme-hydrolyzed beef and pork skin, Satterlee and Zachariah (1973) indicated that the hydrolyzates of beef and pork skin contained greater protein content than nonfat dry milk. The authors observed that the major protein of skin is collagen, when heated, the resulting gelatin is easily enzyme degraded. The significance of protein in meat products has been investigated. Gerrard (1976) observed that addition of protein supplements will assist in fat and moisture retention and increase the nutritive value of meat product. The results of chemical analysis of the four batches of sausages are shown in Table 3. Substitution of fat with rind increased the moisture content of the sausages as the level of rind increased in the product. The highest
411
S.S. Abiola, S.W. Adegbaju / Meat Science 58 (2001) 409–412 Table 3 Effect of replacing pork backfat with pork rind on proximate composition of pork sausagea
Table 4 Effect of replacing pork backfat with rind on refrigeration and cooking weight loss of pork sausagea
Parameters (%)
Parameters (%)
Moisture Ash Fat Protein
Batches (% replacement) 1 (0%)
2 (33%)
3 (66%)
4 (100%)
53.51b 4.48a 24.66a 12.41a
61.58a 3.67b 15.88b 14.96 b
59.50ab 3.89b 14.85b 17.92c
63.27a 3.50b 7.99c 19.77d
a
Means in the same row with different letters are significantly different (P<0.05).
moisture content of 63.27% was obtained on batch 4 sausage with 100% rind replacement level and this conforms with the report that allowable moisture for fresh pork sausage is 4 times the protein concentration plus 3% (CFR, 1990). The fat content decreased with increase in the level of rind in the sausages. The range of 7.99–24.66% fat was recorded in this study while Rankosky (1970) reported a range of 20–30% fat content for comminuted meat products. Dry sausages made with normal recipe have fat content around 32% (Bloukas et al., 1997). In attempts to decrease fat content of meat products, nonmeat ingredients such as soy proteins (Sofos & Allen, 1977), vegetable oils (Paneras & Bloukas, 1994) and olive oil (Bloukas & Paneras, 1993) have been used satisfactorily. Low-fat sausages containing rind had higher values for protein than the control. This could be attributed to the high protein content of pork rind used in this study. Osburn and Keeton (1994) manufactured low-fat prerigor fresh pork sausages and concluded that all treatment sausages were different from the control, exhibiting higher percentage for moisture, protein and lower percentage fat content. The importance of protein in meat product has been documented in other studies. Acton, Zeigler, and Burge (1983) indicated that protein is the most important constituent of sausage because it contributes to the binding qualities. Results of weight losses during refrigeration and cooking of sausage samples are presented in Table 4. The low-fat sausages had lower values for refrigeration losses than the control. A similar trend was observed for cooking loss. The lower refrigeration and cooking losses observed on low-fat sausages could be associated with their higher protein content compared with the control. Proteins have the ability to trap moisture and reduce moisture loss. On heating, gelation of proteins usually results in the formation of a matrix which entraps water and fat and stabilises the sausage. Mittal and Bleisdell (1983) indicated that protein coagulation and associated skin formation at the product surface apparently limit evaporation. However, the report of cooking loss noticed in the present study is contrary to the reports of
Batches (% replacement) 1 (0%)
2 (33%)
3 (66%)
4 (100%)
Refrigeration Initial weight (g) Final weight (g) Weight loss (%)
50.00 44.07 11.85a
50.00 45.14 9.72b
50.00 46.01 7.99b
50.00 45.66 8.67b
Cooking Initial weight (g) Final weight (g) Weight loss (%)
50.00 48.07 3.85
50.00 47.89 4.22
50.00 48.46 3.08
50.00 48.12 3.76
a Means in the same row with different letters are significantly different (P<0.05).
Table 5 Effect of replacing pork backfat with rind on sensory properties of pork sausagea Parameters
Colour Tenderness Juiciness Flavour Acceptability
Batches (% replacement) 1 (0%)
2 (33%)
3 (66%)
4 (100%)
6.30a 5.70 5.30a 6.30a 5.30a
5.60ab 5.40 4.90a 5.50ab 5.00ab
5.60ab 5.30 4.60ab 5.20b 4.50bc
4.80b 4.90 3.90b 4.80b 4.30c
a Means in the same row with different letters are significantly different (P<0.05).
Hughes, Cofrades, and Troy (1997) who observed that decreasing fat content increased cooking losses in processed meats. Table 5 shows a general decrease in sensory properties as fat content decreased in the sausages. The low fat pork sausages (batches 2, 3 and 4) had lower values for colour, tenderness, juiciness, flavour and overall acceptability than the control. The low-fat sausages were darker than the high fat sausage. These findings are in agreement with Hughes et al. (1997) who reported that decreasing fat content of frankfurter from 30 to 5% decreased water-holding capacity, reduced overall acceptability of flavour and caused darker and redder coloration of the reduced fat products. Colour changes were similarly observed when added water was substituted for fat in bolognas (Claus & Hunt, 1991; Claus, Hunt, & Kastner, 1989). To offset this disadvantage water is often used in combination with other ingredients in an attempt to reduce fat level. Substitution of pork back fat with vegetable oils in the production of low-fat frankfurter was also reported to cause lower juiciness (Paneras & Bloukas, 1994). In conclusion, the result of this study indicates that up to 66% of pork back fat can be replaced with rind in pork sausage without adverse effect on processing yield.
412
S.S. Abiola, S.W. Adegbaju / Meat Science 58 (2001) 409–412
This level (i.e. batch 3) produced pork sausage with the highest protein and lowest refrigeration and cooking weight losses. Further research needs to be done for the manufacture of low-fat sausages particularly for tropical countries like Nigeria where consumer perception of the risks associated with high fat intake is now leading to an increased demand for food products low in fat.
Acknowledgements The authors are grateful to Research and Development Centre (RESDEC) of University of Agriculture, Abeokuta, Ogun State, Nigeria for sponsoring this project. We are also grateful to Miss J.A. Adegbite and Mr. A.M. Ishola for Laboratory assistance. References Acton, J. C., Ziegler, G. R., & Burge, D. L. (1983). Functionality of muscle constituents in the processing of comminuted products. Critical Reviews in Food Science and Nutrition, 18, 99–121. AOAC (1990). Official methods of analysis. (15th ed.). Washington, DC, USA: Association of Official Analytical Chemists. Bloukas, J. G., & Paneras, E. D. (1993). Substituting olive oil for pork backfat affects quality of low-fat Frankfurters. Journal of Food Science, 58(4), 705–709. Bloukas, J. G., Paneras, E. D., & Fournitzis, G. C. (1997). Effect of replacing pork backfat with olive oil on processing and quality characteristics of fermented sausages. Meat Science, 45(2), 133–144. Briggs, G. M., & Schweigert, B. S. (1990). An overview of meat in the diet. Ch. 1. In A. M. Pearson, & T. R. Dutson, Meat and Health (pp. 1–18). New York: Elsevier Applied Science. CFR, (1990) Code of Federal Regulations. Animal and animal products, No 9, Ch. 111, Section 319, Washington DC. Claus, J. R., Hunt, M. C., & Kastner, C.L. (1989). Effects of substituting added water for fat on the textural, sensory and processing characteristics of bologna. Journal of Muscle Foods, 1, 1. Claus, J. R., Hunt, M. C., Kastner, C. L., & Kropf, D. H. (1990). Low-fat, High-added water bologna: Effects of massaging, preblending, and time of addition of water and fat on physical and sensory characteristics. Journal of Food Science, 55(2), 338–341. Claus, J. R., & Hunt, M. C. (1991). Low-fat, High added-water
bologna formulated with texture-modifying ingredients. Journal of Food Science, 55(3), 643–647. Gerrard, F. (1976). A practical handbook on the manufacture of sausage and other meat-based products, (6th ed.). London: Northwood Publications Ltd. Harvey, W. R. (1990). Mixed model least squares and maximum likelihood computer programme. Columbus: Ohio State University. Hughes, E., Cofrades, S., & Troy, D. J. (1997). Effects of fat level, oat fibre and carrageenan on Frankfurters formulated with 5, 12 and 30% fat. Meat Science, 45(3), 273–281. Lister, D. (1996). The meat we eat: Notions of quality for today or tomorrow. 2. The appeal and organoleptic properties of meat. Outlook on Agricriculture, 25(4), 263–266. Mattson, F. H., & Grundy, S. M. (1985). Comparison of effects of dietary saturated, mono-unsaturated and polyunsaturated fatty acids on plasma lipids and lipoproteins in man. Journal of Lipid Research, 26, 194. Mittal, G. S., & Blaisdell, J. L. (1983). Weight loss in Frankfurters during thermal processing. Meat Science, 9(2), 79–88. Osburn, W. N., & Keeton, J. T. (1994). Konjac four Gel as fat substitute in low-fat prerigor fresh pork sausage. Journal of Food Science, 59(3), 484–489. Osburn, W. N., Mandigo, R. W., & Eskridge, K. M. (1997). Pork skin connective tissue gel utilization in reduced-fat bologna. Journal of Food Science, 62(6), 1176–1182. Paneras, E. D., & Bloukas, J. G. (1994). Vegetable oils replace pork backfat for low-fat Frankfurters. Journal of Food Science, 59(4), 725–728. Park, J., Rhee, K. S., & Ziprin, Y. A. (1990). Low-fat Frankfurters with elevated levels of water and oleic acid. Journal of Food Science, 55(3), 871–874. Puolanne, E., & Ruusunen, M. (1981). The properties of connective tissue membrane and pork skin as raw materials for cooked sausage. Meat Science, 5, 371–382. Rankosky, J. (1970). Soy products for the meat industry. Journal of Agricultural and Food Chemistry, 18, 1005. Satterlee, L. D., & Zachariah, N. Y. (1973). Utilization of beef and pork skin hydrolysates as a binder or extender in sausage emulsions. Journal of Food Science, 38, 268–270. Sofos, J. N., & Allen, C. E. (1977). Effects of lean meat source and levels of fat and soy protein on properties of wiener-type products. Journal of Food Science, 42, 875. Steel, R. G. D., & Torrie, J. H. (1980). Principle and procedure of statistics. A biometrical approach, (2nd ed.). McGraw Hill, Kogakusha Ltd. . Yang, A., Trout, G. R. and Barry, B. J. (1995) Proceedings 41st Inter. Congress of Meat Sci. and Technol. San Antonio, TX, D-7, p 435.
Effect of substituting pork backfat with rind on quality characteristics of pork sausage S. S. Abiola *, S. W. Adegbaju Department of Animal Production and Health, University of Agriculture, PMB 2240, Abeokuta, Ogun State, Nigeria Received 1 February 2000; received in revised form 22 January 2001; accepted 22 January 2001
Abstract A study was conducted in which pork backfat in pork sausage was replaced with rind at 0, 33, 66 and 100% levels. The high moisture and high protein content of rind consequently influenced the moisture and protein content of the final products. The fat level decreased with increase in the level of rind in the sausage. The lowest fat content of 7.99% was recorded on batch 4 sausage with 100% rind replacement level. Replacement of pork backfat with rind decreased refrigeration and cooking weight losses. The values obtained for sensory properties decreased with increase in the level of rind in the sausage. Up to 66% pork backfat can be replaced with rind in pork sausage without adverse effect on processing yield. # 2001 Elsevier Science Ltd. All rights reserved. Keywords: Substitution; Pork backfat; Rind; Characteristics; Pork sausage
1. Introduction Fat is an important constituent of processed meat products because it affects tenderness and juiciness. A high fat content is traditionally associated with succulence and flavour (Lister, 1996). However, the composition of fat in the human diet is becoming increasingly important because of apparent relationship between the amount and type of fat consumed and the incidence of coronary heart disease. Briggs and Schweigert (1990) indicated that pork backfat used in fermented sausage has about 40% saturated fatty acids. In the study of dietary fatty acids, the advantages of mono-unsaturated fatty acids over saturated and polyunsaturated fatty acids was reported (Mattson & Grundy, 1985). To decrease caloric density and to lower the intake of total dietary fat, saturated fatty acids and cholesterol, attempts have been made to replace fat with non-meat ingredients such as soy proteins (Sofos & Allen, 1977), vegetable oils (Paneras & Bloukas, 1994) added water (Claus, Hunt, & Kastner, 1990; Park, Rhee, & Ziprin, 1990), olive oil (Bloukas, Paneras, &
* Corresponding author. Tel.: +234-39-200190, ext. 177; fax: +234-39-234650.
Fournitzis, 1997) and carbohydrates (Yang, Trout, & Barry, 1995) without adverse effects on processing yield. Osburn, Mandigo, and Eskridge (1997) utilised pork skin connective gels satisfactorily in reduced-fat bologna. Pork skin was also used as raw materials for meat products in other studies (Puolanne & Ruusunen, 1981; Satterlee & Zachariah, 1973). This study investigated the effect of substituting pork backfat with rind on chemical, storage and sensory properties of pork sausage.
2. Materials and methods The thigh muscle and backfat obtained from an adult Large White boar slaughtered on the Teaching and Research Farm of University of Agriculture, Abeokuta, Ogun State, Nigeria were used for the study. The meat and fat were run separately through a 5-mm plate in a Kenwood machine and later frozen till the second day. Pork skin removed from the loin of the slaughtered pig was soaked in distilled water overnight and later used for the preparation of rind. Backfat on the skin was trimmed before and after scalding. Scalding in hot water at 61 C lasted for 5 min to ensure proper removal of pig hair from the follicle. The de-fatted skin was minced
0309-1740/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved. PII: S0309-1740(01)00043-2
410
S.S. Abiola, S.W. Adegbaju / Meat Science 58 (2001) 409–412 Table 1 Composition (%) of pork sausages Ingredients
Lean pork Pork backfat Pork rind Wheat flour Water Ascorbic acid Seasoning Total
Batches 1 (0%)
2 (33%)
3 (66%)
4 (100%)
55.56 12.33 – 15.11 15.11 0.05 1.84
55.56 8.26 4.07 15.11 15.11 0.05 1.84
55.56 4.19 8.14 15.11 15.11 0.05 1.84
55.56 – 12.33 15.11 15.11 0.05 1.84
100.00
100.00
100.00
100.00
Table 2 Proximate composition of pork rind Parameters
% Composition
Moisture Ash Fat Protein
40.92 1.82 28.69 27.01
Fig. 1. Flow diagram of sausage preparation.
with the Kenwood machine and later used as cooked minced rind. Proximate analysis of the rind was determined according to the method of AOAC (1990). Four batches of pork sausage (5 kg/batch) were prepared in which rind replaced pork backfat at 0, 33, 66 and 100% levels. Equal amounts of seasoning, water and wheat flour were added to each batch of pork sausage. Ingredient composition of the sausages is presented in Table 1 while the flow diagram of sausage preparation is shown in Fig. 1. Samples of the pork sausage from each batch were stuffed separately into pig casing (35 mm diameter) and refrigerated at 2 C for 24 h while some samples were cooked in water bath at 80 C for 15 min. Treatment in both cases was replicated three times and the study was repeated twice. Refrigeration loss was based on pre- and post-refrigeration weight of samples while cooking loss was the difference between fresh and cooked weights. Taste panel sensory evaluation of cooked samples was performed by 10 trained panelists. Parameters monitored were colour, flavour, juiciness, tenderness and acceptability. Each panelist was asked to rinse his mouth between each sample tested to avoid carry over effect. The evaluators scored each sample on a 7-point scale (1=unacceptable; 7=excellent). Data collected were subjected to analysis of variance while means were compared using the Duncan’s New Multiple Range Test (Steel & Torrie, 1980). Model used was (Harvey, 1990): Yij ¼ þ ai ¼ eij
where: Yij=dependent variable; =population constant; ai=effect due to the replacement of fat with rind (i=1,2,3 and 4); and eij=residual error with zero mean and variance 2.
3. Results and discussion The results of chemical composition of pork rind are presented in Table 2. Moisture content of pork rind was 40.92% while that of ash was 1.82%. Osburn et al. (1997) obtained 44.24% moisture content for raw pork skin connective tissue. The value obtained for the fat content of rind in the present study was 28.69% while that of protein was 27.01%. Osburn et al. (1997) reported values of 28.29% for fat and 26.47% for protein of raw pork skin connective tissue. In the manufacture of sausage with enzyme-hydrolyzed beef and pork skin, Satterlee and Zachariah (1973) indicated that the hydrolyzates of beef and pork skin contained greater protein content than nonfat dry milk. The authors observed that the major protein of skin is collagen, when heated, the resulting gelatin is easily enzyme degraded. The significance of protein in meat products has been investigated. Gerrard (1976) observed that addition of protein supplements will assist in fat and moisture retention and increase the nutritive value of meat product. The results of chemical analysis of the four batches of sausages are shown in Table 3. Substitution of fat with rind increased the moisture content of the sausages as the level of rind increased in the product. The highest
411
S.S. Abiola, S.W. Adegbaju / Meat Science 58 (2001) 409–412 Table 3 Effect of replacing pork backfat with pork rind on proximate composition of pork sausagea
Table 4 Effect of replacing pork backfat with rind on refrigeration and cooking weight loss of pork sausagea
Parameters (%)
Parameters (%)
Moisture Ash Fat Protein
Batches (% replacement) 1 (0%)
2 (33%)
3 (66%)
4 (100%)
53.51b 4.48a 24.66a 12.41a
61.58a 3.67b 15.88b 14.96 b
59.50ab 3.89b 14.85b 17.92c
63.27a 3.50b 7.99c 19.77d
a
Means in the same row with different letters are significantly different (P<0.05).
moisture content of 63.27% was obtained on batch 4 sausage with 100% rind replacement level and this conforms with the report that allowable moisture for fresh pork sausage is 4 times the protein concentration plus 3% (CFR, 1990). The fat content decreased with increase in the level of rind in the sausages. The range of 7.99–24.66% fat was recorded in this study while Rankosky (1970) reported a range of 20–30% fat content for comminuted meat products. Dry sausages made with normal recipe have fat content around 32% (Bloukas et al., 1997). In attempts to decrease fat content of meat products, nonmeat ingredients such as soy proteins (Sofos & Allen, 1977), vegetable oils (Paneras & Bloukas, 1994) and olive oil (Bloukas & Paneras, 1993) have been used satisfactorily. Low-fat sausages containing rind had higher values for protein than the control. This could be attributed to the high protein content of pork rind used in this study. Osburn and Keeton (1994) manufactured low-fat prerigor fresh pork sausages and concluded that all treatment sausages were different from the control, exhibiting higher percentage for moisture, protein and lower percentage fat content. The importance of protein in meat product has been documented in other studies. Acton, Zeigler, and Burge (1983) indicated that protein is the most important constituent of sausage because it contributes to the binding qualities. Results of weight losses during refrigeration and cooking of sausage samples are presented in Table 4. The low-fat sausages had lower values for refrigeration losses than the control. A similar trend was observed for cooking loss. The lower refrigeration and cooking losses observed on low-fat sausages could be associated with their higher protein content compared with the control. Proteins have the ability to trap moisture and reduce moisture loss. On heating, gelation of proteins usually results in the formation of a matrix which entraps water and fat and stabilises the sausage. Mittal and Bleisdell (1983) indicated that protein coagulation and associated skin formation at the product surface apparently limit evaporation. However, the report of cooking loss noticed in the present study is contrary to the reports of
Batches (% replacement) 1 (0%)
2 (33%)
3 (66%)
4 (100%)
Refrigeration Initial weight (g) Final weight (g) Weight loss (%)
50.00 44.07 11.85a
50.00 45.14 9.72b
50.00 46.01 7.99b
50.00 45.66 8.67b
Cooking Initial weight (g) Final weight (g) Weight loss (%)
50.00 48.07 3.85
50.00 47.89 4.22
50.00 48.46 3.08
50.00 48.12 3.76
a Means in the same row with different letters are significantly different (P<0.05).
Table 5 Effect of replacing pork backfat with rind on sensory properties of pork sausagea Parameters
Colour Tenderness Juiciness Flavour Acceptability
Batches (% replacement) 1 (0%)
2 (33%)
3 (66%)
4 (100%)
6.30a 5.70 5.30a 6.30a 5.30a
5.60ab 5.40 4.90a 5.50ab 5.00ab
5.60ab 5.30 4.60ab 5.20b 4.50bc
4.80b 4.90 3.90b 4.80b 4.30c
a Means in the same row with different letters are significantly different (P<0.05).
Hughes, Cofrades, and Troy (1997) who observed that decreasing fat content increased cooking losses in processed meats. Table 5 shows a general decrease in sensory properties as fat content decreased in the sausages. The low fat pork sausages (batches 2, 3 and 4) had lower values for colour, tenderness, juiciness, flavour and overall acceptability than the control. The low-fat sausages were darker than the high fat sausage. These findings are in agreement with Hughes et al. (1997) who reported that decreasing fat content of frankfurter from 30 to 5% decreased water-holding capacity, reduced overall acceptability of flavour and caused darker and redder coloration of the reduced fat products. Colour changes were similarly observed when added water was substituted for fat in bolognas (Claus & Hunt, 1991; Claus, Hunt, & Kastner, 1989). To offset this disadvantage water is often used in combination with other ingredients in an attempt to reduce fat level. Substitution of pork back fat with vegetable oils in the production of low-fat frankfurter was also reported to cause lower juiciness (Paneras & Bloukas, 1994). In conclusion, the result of this study indicates that up to 66% of pork back fat can be replaced with rind in pork sausage without adverse effect on processing yield.
412
S.S. Abiola, S.W. Adegbaju / Meat Science 58 (2001) 409–412
This level (i.e. batch 3) produced pork sausage with the highest protein and lowest refrigeration and cooking weight losses. Further research needs to be done for the manufacture of low-fat sausages particularly for tropical countries like Nigeria where consumer perception of the risks associated with high fat intake is now leading to an increased demand for food products low in fat.
Acknowledgements The authors are grateful to Research and Development Centre (RESDEC) of University of Agriculture, Abeokuta, Ogun State, Nigeria for sponsoring this project. We are also grateful to Miss J.A. Adegbite and Mr. A.M. Ishola for Laboratory assistance. References Acton, J. C., Ziegler, G. R., & Burge, D. L. (1983). Functionality of muscle constituents in the processing of comminuted products. Critical Reviews in Food Science and Nutrition, 18, 99–121. AOAC (1990). Official methods of analysis. (15th ed.). Washington, DC, USA: Association of Official Analytical Chemists. Bloukas, J. G., & Paneras, E. D. (1993). Substituting olive oil for pork backfat affects quality of low-fat Frankfurters. Journal of Food Science, 58(4), 705–709. Bloukas, J. G., Paneras, E. D., & Fournitzis, G. C. (1997). Effect of replacing pork backfat with olive oil on processing and quality characteristics of fermented sausages. Meat Science, 45(2), 133–144. Briggs, G. M., & Schweigert, B. S. (1990). An overview of meat in the diet. Ch. 1. In A. M. Pearson, & T. R. Dutson, Meat and Health (pp. 1–18). New York: Elsevier Applied Science. CFR, (1990) Code of Federal Regulations. Animal and animal products, No 9, Ch. 111, Section 319, Washington DC. Claus, J. R., Hunt, M. C., & Kastner, C.L. (1989). Effects of substituting added water for fat on the textural, sensory and processing characteristics of bologna. Journal of Muscle Foods, 1, 1. Claus, J. R., Hunt, M. C., Kastner, C. L., & Kropf, D. H. (1990). Low-fat, High-added water bologna: Effects of massaging, preblending, and time of addition of water and fat on physical and sensory characteristics. Journal of Food Science, 55(2), 338–341. Claus, J. R., & Hunt, M. C. (1991). Low-fat, High added-water
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