The influence of fat substitution with κ‐carrageenan, konjac, and tragacanth on the textural properties of low‐fat sausage

Abstract Reducing the fat content of meat products and producing healthier products is considered as an important matter in politics in prevention of many hazardous diseases and providing consumers' health. The aim of this study was reducing the fat in fatty sausages based on oil reduction and using fat substitutes, including κ‐carrageenan, konjac, and tragacanth, and comparing them according to their texture characteristics. κ‐carrageenan, konjac, and tragacanth gums were used at four different levels (0.0, 0.5, 1.0, and 1.5) as the fat substitutes in producing low‐fat sausage with 70% reduction based on formulated oil. Texture profile analysis (Hardness, Gumminess, Springiness, and Chewiness) was performed in this study for analyzing the texture characteristics, in 1‐, 10‐, 20‐, and 30‐day time intervals after production. The results showed that producing low‐fat sausage was possible using all the three gums, among the low‐fat samples of which, the texture samples containing konjac were more favorable. Textural properties indicated that fat reduction increased in firmness and gum addition can partially compensate deficits in rheological properties, although during the storage, low‐fat sausages without any gum have highest decline in Hardness. Konjac gum illustrated the best theological properties between treatments.

edibility characteristic. Reducing or eliminating it produces a product with dry and elastic texture (Soltanizadeh & Kadivar, 2011).
Maintaining appropriate texture characteristics in low-fat or nonfat food materials is considered a main problem, in this respect.
Due to some texturing materials, the required texture by the consumers can be produced in compound food materials (Bourne 2002). This is possible using fat substitutes, such as hydrocolloids, vegetable proteins, and connective tissue proteins (Cierach et al., 2009). The use of carbohydrates, especially hydrocolloids, as the fat substitutes in meat products modifies texture and sensory characteristics of meat products (Farahnaki, Majzoubi, & Mesbahi, 2008).
One of the best and most effective fat substitutes is κcarrageenan (Cierach et al., 2009). Using κ-carrageenan has been common in meat product industry for many years, having appropriate effects, and the effects of other compositions on the products or as the fat substitutes can even be compared with it. The other compound in this regard is konjac (glucomannane) Soltanizadeh & Kadivar, 2011). This composition is obtained from the yam roots, a polysaccharide that is classified under glucomannane species (Soltanizadeh & Kadivar, 2011). The main composition of konjac powder is glucomannane, called konjac mannane (Phillips & Williams, 2009). Konjac powder is considered as a safe and low-calorie compound containing indigestible fibers and has various physiologic effects with therapeutic applications (González Canga et al., 2004). The other composition is tragacanth, which is among the secretory gums and one of the first emulsifiers and stabilizers, used in little amounts in food materials (Alemzadeh, Amin Mohammadifar, Azizi, & Ghanati, 2010;Farahnaki et al., 2008). The suitable oral sense and texture can be created with appropriate amounts of tragacanth gum. The aim of this study was producing three types of low-fat sausage according to reducing formulated oil and using fat substitutes, including κcarrageenan, konjac, and tragacanth hydrocolloids, and comparing the effects of each one on Hardness, Gumminess, Springiness, and Chewiness of low-fat sausage texture characteristics and also comparing them with each other.

| Formulation
The amount of beef fat (the purchased beefsteak from Mataboi Co., Brazil) was balanced with the rate of 12% for formulation and producing the sausage sample with 40% of red meat. According to Table 1, the raw materials, including oil (Naz Co., Iran), flour (Joree Co., Iran), gluten and starch (Shahdineh Aran Co., Iran), salt (Goharnab Co., Iran), poly phosphate sodium (Budenheime Co., Germany), ascorbic acid and sodium nitrite (Basf Co., Germany), garlic and spices (local market), ice and water (local market), κ-carrageenan gels with 10% (sifted with sieve no. 120 from CEAMSA Co., Spain), konjac flour (sifted with sieve no. 120 from Gemfont Co., Taiwan), and tragacanth (produced from Astragalus gossypinus Fischer, milled and sifted with sieve no. 120 purchased from the local market) were crushed and mixed in Mini-cutter (Minika, Spain) for about 10 min, under temperature conditions of under 6°C, and the resulted mixture was packed in a 60-mm diameter polyamide cover by the filling device (Handtmann Inc., Germany). Then, the sausages went under 72-75°C for 100 min by water steam in the curing compartment, and immediately after that, the temperature was reduced to less than 30°C by cold air (0-4°C). The products were then quarantined TA B L E 1 Formulation of produced sausage samples and kept in the cold storage with 0-4°C, for the required tests (Rokni, 1998).

| Texture profile analysis
Texture profile analysis (TPA) was used to evaluate texture char- Each test was performed with at least three repetitions. Hardness, Springiness, Gumminess, and Chewiness factors were evaluated in the test (Bourne, 2002;Jiménez-Colmenero et al., 2010). Gumminess and Chewiness are functions of Hardness and cohesiveness, in addition as described in Equation (2) Chewiness in also dependent on Springiness.

| Statistical analysis
One-way ANOVA was used to determine statistical difference between treatments (p < .05), for this purpose SPSS ver 19 has been used. (Valizadeh & Moghadam, 2010).

| RE SULTS
According to Table 2 for the comparison of mean values, it can be found that reducing oil and fat substitutes with κ-carrageenan reduces the rate of Hardness as compared to the control samples, such that this rate has significant reduction in the samples with no gum, but by increasing the gum (0.5% level), this rate gets significant increase relative to the samples without gum (p < .05), and by concentration increase(1% level), the Hardness gets a higher increase, and at 1.5% level of the gum, the Hardness reaches to less than the 1% level.
According to Table 3 for the comparison of mean values, it can be found that reducing oil and fat substitute with κ-carrageenan reduces the Gumminess as compared to control samples, such that the Gumminess of the samples without gum has significant reduction as compared to the control samples (p < .05), but it increases significantly by adding the κ-carrageenan in 0.5 and 1% levels. Then, by increasing the substitute level in 1.5% level, the Gumminess decreases to lower level than 1% of gum, and this rate shows a significant reduction in all levels as compared to the control samples (p < .05). Thus, adding κ-carrageenan in all levels increases the Gumminess in low-fat sausages, the reason of which is that as Gumminess is the result of the product of the two Hardness and cohesiveness factors in each other, then due to increasing the Hardness in the sausage because of adding the gum, the required energy is also increased for disjoining the sausage for swallowing (Ayadi, Kechaou, Makni, & Attia, 2009;Hellyer, 2004). Moreover, after 30 days of preserving time, Gumminess shows reduction in all samples, which is only significant for the samples containing 0.5% κ-carrageenan (p < .05).
(1) Gumminess = Hardness.Cohesiveness  is observed between the samples (p > .05). Therefore, adding κ-carrageenan increases the Springiness partially in low-fat sausage, which is in conformity with the results obtained by Pietrasik and Jarmoluk (2003) about the obtained gel from port. Moreover, after 30 days of preserving time, Springiness shows a partial increase in all samples (p > .05).
As shown in Table 4, it can be found that reducing oil and fat substitute with konjac reduces the Springiness as compared to control samples, the Springiness of the samples without gum has a partial reduction as compared to the control samples (p > .05), but it increases partially by increasing the gum in 0.5% level (p > .05). Then, the gum obtains a higher Springiness by increasing the density of the gum in 1% level, and at 1.5% level, the Springiness reduces to lower than 1% level (p < .05). Therefore, adding konjac in 0.5% and 1% levels partially increases the Springiness in low-fat sausages. Moreover, after 30 days of preserving time, Springiness shows a partial increase in all the samples.

| D ISCUSS I ON
As illustrated in Table 2, Hardness showed a significant decrease (in different treatments) compared with the control samples (p < .05). Candogan and Kolsarici (2003), Matulis, McKeith, Sutherland, and Brewer (1995), He and Sebranek (1996) also believe that by increasing the density of κ-carrageenan, the texture of low-fat frankfurters becomes harder. The results have had conformity up to 1% level in this study. Moreover, according to the viewpoint of Ayadi et al.  reduce the Hardness as compared to the control samples, such that the Hardness of the samples without gum has significant reduction as compared to the control samples (p < .05), but by adding the gum (0.5% level), the Hardness shows significant reduction as compared to the samples without gum, and by increasing the substitute level (1% and 1.5% levels), the Hardness shows a higher increase (p < .05).
The rate of Hardness of the samples containing gum shows a significant reduction as compared to the control samples (except 1.5% level with a negligible reduction) (p < .05). Thus, adding konjac in all levels increases Hardness in low-fat sausage, which is in conformity with the results obtained by Liaros, Katsanidis, and Bloukas (2009) and also Ruiz-Capillas, Triki, Herrero, Rodriguez-Salas, and Jiménez-Colmenero (2012), one reason of which is that due to heating of konjac gel, hydrogen bonds are weakened, and hydrophobic mutual reactions (polymer-polymer) are improved, and Hardness increases by stabilization of konjac gel (Hellyer, 2004 which is only significant for the samples containing 0.5% tragacanth (p < .05). Generally, the texture is softened in low-fat samples as compared to control samples, which is in conformity with the results obtained by Claus, Hunt, and Kastner (1989), Hensley and Hand (1995), and also Candogan and Kolsarici (2003), the reason of which is probably according to the viewpoint of Triki et al. (2013) due to increasing the humidity ratio to protein. Also, according to Ruusunen et al. (2003), when fat is replaced with water in equal weights in the formulation, the texture becomes softer, Sutton, Hand, and Newkirk (1995) stated that there is a negative correlation between Hardness and humidity in frankfurters. Generally, regarding Hardness, the highest rate of it was related to the control samples, and the lowest rate of it was related to the samples containing tragacanth with 1.5% level, which showed significant changes (p < .05). According to Table 3 for the comparison of mean values, it can be found that reducing oil and fat substitute with konjac reduces the Gumminess as compared to control samples, such that by adding gum (in 0.5% and 1% levels), the Gumminess of the samples shows significant increase (p < .05), and by increasing the substitute level in 1.5% level of gum, the Gumminess shows again a significant increase as compared to the samples without gum and shows significant reduction as compared to the control samples in all levels (p < .05) decreases to lower level than 1% of gum, and this rate shows a significant reduction in all levels as compared to the control samples (p < .05). Thus, adding konjac in all levels improves Gumminess in low-fat sausage, and the reason for the increase is that since Gumminess is the result of the product of the two Hardness and cohesiveness factors in each other. According to the mean comparison Table 3, it can be realized that reducing oil and fat substitute with tragacanth decreases Gumminess as compared to the control samples, such that it has significant reduction in the samples without the gum as compared to the control samples (p < .05), and by adding tragacanth (in 0.5% level), the amount of it has a partial increase as compared to the samples without the gum (p > .05), and by increasing the substitute level (1% and 1.5% levels), in comparison with the samples without gum, the rates show a partial reduction (p > .05) and significant reduction, respectively, indicating significant reduction in all levels as compared to the control samples (p < .05). Therefore, adding tragacanth has caused increasing Gumminess in low-fat sausage, only in 0.5% level, and the reason for the increase is due to increasing Hardness of the sausage because of adding the gum (only in this level, as compared to the samples without gum), and the required energy is increased for disjoining the sausage for swallowing (Ayadi et al., 2009;Hellyer, 2004  The increasing rate of Chewiness up to 1% of the gum is in conformity with the results obtained from Ayadi et al. (2009), about the effect of κ-carrageenan on turkey sausage. Thus, adding κcarrageenan in all levels improves the Chewiness in low-fat sausages, which is in conformity with the research by Pietrasik and Jarmoluk (2003) about the results on pork, and the reason for the increase is that since Chewiness is the result of the product of the two Gumminess and Springiness factors in each other, then according to the increase in Gumminess and Springiness of sausage because of adding gum as compared to the samples without the gum, the required energy for oral digestion of sausage for swallowing is increased (Ayadi et al., 2009;Hellyer, 2004 (Ayadi et al., 2009;Hellyer, 2004).
Moreover, after 30 days of preserving time, Chewiness shows a partial decrease in all the samples (p > .05).
According to Table 5 (comparison of mean values), it can be found that reducing oil and fat substitute with tragacanth reduces the Chewiness as compared to control samples, such that the Chewiness of the samples without gum has significant reduction as compared to the control samples (p < .05), but by adding gum (at 0.5% level), Gumminess increases a little (p > .05), and by increasing the substitute level (1% and 1.5% levels), the Chewiness is reduced to the extent that its rate as compared to the samples without gum shows partial reduction (p > .05) and significant reduction (p < .05), respectively, having significant reduction in all levels as compared to the control sample (p < .05). Therefore, adding tragacanth in only 0.5% level partially increases Chewiness in low-fat sausages, and the reason for the increase is due to increasing Gumminess and Springiness of the sausage because of adding the gum (only in this level, as compared to the samples without gum), and the required energy is increased for oral digestion of the sausage for swallowing (Ayadi et al., 2009;Hellyer, 2004). Moreover, after 30 days of preserving time, Chewiness shows a partial reduction in control samples and samples with no gum, but it shows a partial increase in the samples containing tragacanth (p > .05).
Generally, regarding Chewiness, the highest rate of it is related to the control sample, and the lowest rate is related to the samples containing tragacanth with 1.5% level, and the changes are significant (p < .05). Moreover, the closest samples compared with the control sample are the ones containing 1.5% konjac (p > .05).

| CON CLUS ION
Comparison between important factors that may effective on the customer acceptance, textural factors have the most important position. As shown, considering the textural factors such as Hardness, Gumminess, Springiness, and Chewiness, sample containing 1.5% konjac is more favorable to formulate low-fat sausage than kcarrageenan and tragacanth.

CO N FLI C T O F I NTE R E S T
The authors declare no conflict of interest.