Effects of Corn Oil and Broccoli on Instrumental Texture and Color Properties of Bologna-Type Sausage

Abstract

The effects of substitution of sheep tail fat with corn oil (50%) and the addition of broccoli (0, 5, or 10%) on the instrumental texture and color properties of bologna-type sausage were investigated during chilled storage (90 days at 4°C). Thiobarbituric acid-reactive substances and pH analysis were also carried out in fresh and storaged samples. The substitution of sheep tail fat by corn oil had very significant (P < 0.01) effects on the color scores (L*, a*, and b*) and textural properties of samples. The use of broccoli affected significantly (P < 0.01) color scores and hardness, gumminess, and chewiness values. Storage time had significant effects (P < 0.01) on hardness, springiness and cohesiveness, and color scores. The use of corn oil in bologna-type sausage decreased thiobarbituric acid-reactive substances value. However, at the end of storage this value was not over 15 μmol MDA/kg in sausage with animal fat. The pH values were not below 6.1 at the end of the storage.

Keywords:

• Bologna-type sausage
• Broccoli
• Corn Oil
• TPA

INTRODUCTION

Bologna-type sausage is an emulsion type meat product that is widely consumed. It usually contains fat as high as 30%. Use of animal fat in meat products gives a certain taste and flavor and improves the textural properties of the product.[1,2] In recent years, there has been decrease in popularity of meat products because of high cholesterol and unsaturated fatty acid content.[2,3] Meat products with high fat levels, especially emulsion type meat products, are subject to studies that aim to reduce fat levels.

Reducing fat in emulsion-type meat products causes an increase in consumer demand due to a decrease in the amount of calories and cholesterol, but products become uninspired and dry, have hard structures, and change color. As a result, a reduction in the products' sensory characteristics occur.[4] Substituting animal fat with vegetable oils (corn oil, sunflower oil, olive oil, palm oil, cotton oil, soybean oil, hazelnut oil, etc.) has been the subject of various researches to solve the problem of changing fat ratio in emulsion-type meat products.[5–10] Vegetable oils reduce the plazma LDL-cholesterol, which causes coronary health diseases because of their high mono and poly unsaturated fatty acid composition.[11] There has not been an observation of a significant reduction in the general acceptance of emulsion-type meat products in those studies related to use of vegetable oils. However, various studies stated that the products manufactured with these types of oils had lower yields and textural parameters than those manufactured with animal fat, but had lower cholesterol levels and more health benefits.[6,8,12]

Vegetables with their high fiber, low energy density, and low fat content can supply vitamins; potassium; dietary antioxidants, such as caretenoids and flavonoids; and some potentially beneficial phytochemicals to the products.[13] Broccoli is a member of Brassica familia. This vegetable contains phytochemicals, such as glycosinolate, indole-3 carbinol, isothiocyanates, and sulforaphane; antioxidant vitamins; and flavonoids.[14] So it is preferred by consumers. There are quite a number of studies about the possibility of using vegetable oils in the manufacturing of emulsion-type meat products.[5–10,15,16] But, there is no research on using broccoli in the manufacturing of emulsion-type sausages (bologna, hot dogs, frankfurters, wieners). Bologna and frankfurters are widely consumed meat products in Turkey. The processing technology for bologna is similar to that for frankfurter. However, bologna is much larger in diameter. Color and texture are very important quality criteria in this type of product. However, the use of broccoli and other vegetables in terms of functional properties is desirable in bologna and frankfurter. On the other hand, corn oil is cheaper than animal fat. The aim of this study was to determine the possibilities of using broccoli in bologna-type sausages, which are manufactured by using animal fat and/or vegetable oils, and to obtain a functional product and, consequently, to determine the chemical and physical changes during the storage.

MATERIALS AND METHODS

Materials

Beef meat and sheep tail fat were obtained from a commercial slaughter house in Erzurum, Turkey and were trimmed of all external fat. The lean meat and sheep tail fat were ground through a 3-mm plate and were stored in 4 ± 1°C and −18°C, respectively. Spice mix (spice mix for bologna-type sausage) and additive mix (polyphosphates, sodium erythorbate, sodium citrate, dextrine, dextrose, monosodium glutamate, ascorbic acid, and ascorbate) were obtained from Aksun Food (Istanbul, Turkey). Broccoli and corn oil were obtained from a local market. Broccoli's leaves were separated for the sausage manufacture and frozen at −18°C.

Sausage Manufacture

The sausages were produced according to the formula (2.5 kg lean meat, 1.5 kg fat, 1.25 kg ice) described by Sielaff.[17] Per kg of meat and fat, 25 g of nitrite curing salt, 12.5 g of spice mix, and 8 g of additive mix were used, and this product was described as the control group. In this study, 12 different batters were prepared with different broccoli levels (0, 5, and 10%, calculated as the percentage of the weight of meat only) and animal fat and/or corn oil (100% animal fat, 50% animal fat + 50% corn oil).

Lean meat was chopped for 1 min in a laboratory-type cutter (MADO Typ MTK 662; Dornhan, Schwarzwald, Germany) at low speed and mixed with nitrite and salt at 8°C. Then 2/3 (two-thirds) of the ice was added and chopped at a high speed to 6–8°C. After that, fat and the additive mix were added to the batch. The spice mix was added at 12°C and the remaining ice was added at 11°C and chopped at high speed. Broccoli was added at 9°C and the batter was chopped for three cycles at low speed. The mixture of batters were stuffed into casings (fibrous cellulose casing, 60 mm, Kalle Nalo; Wursthüllen, Wiesbaden, Germany) with a laboratory-type filling machine (Mado Typ MTK 591; Dornhan, Schwarzwald) and clipped (Poly-clip System, SCH 7210; Hattersheim, Germany). Sausages were cooked in a humid oven (Arı Torna, Istanbul, Turkey) to a core temperature of 75°C. After cooking, the sausages were cooled off with a cold shower and stored at 2 ± 1°C for 24 h. Finally, sausages were stored at 4 ± 1°C for 90 days.

Physicochemical Analysis

pH value of the sausages were measured using a pH meter (ATI ORION 420 A; The Scrafft Center, Boston, MA, USA) in a homogenate prepared with 10 g of sausage and 100 ml of distilled water. Lipid oxidation of the sausages was determined according to the TBARS methods of Lemon[18] and was expressed as μmol malonaldehyde per kg of meat. Color measurements of sausages were performed in triplicate using a Minolta colorimeter (CR-200; Minolta Co., Osaka, Japan). L* (lightness), a* (redness), and b* (yellowness) were measured on an (internal) cross-section immediately after each sample was cut.

Instrumental Texture Profile Analysis

The textural characteristics of sausages were analyzed according to texture profile analysis (TPA)[19] using the texturometer TA.XTplus (Stable Micro Systems, Godalming, Surrey, UK) equipped with a 50-mm probe (P/50). TPA was performed using central cores of five slices of each sample (1.5 cm high and 2.5 cm in diameter), which were compressed twice to 50% of their original thickness. The TPA method was carried out under these conditions: pre-test speed—1 mm s⁻¹, test speed—2 mm s⁻¹, post-test speed—3 mm s⁻¹, trigger type—auto/force 20 g, time—5 s. The following parameters were calculated from a force–time graph: hardness (N) = maximum force required to compress the sample (H); springiness (cm) = ability of sample to recover its original form after a deforming force was removed (S); cohesiveness = extent to which sample could be deformed prior to rupture (A ₂/A ₁; A ₁ being the total energy required for the first compression and A ₂ being the total energy required for the second compression); gumminess (N) = force necessary for disintegrating a semisolid sample for swallowing (H × cohesiveness); chewiness (N cm) = work to masticate the sample for swallowing (S × gumminess).

Statistical Analysis

A factorial experiment with adding broccoli (0, 5, and 10%), substitution of sheep tail fat (100% animal fat and 50% animal fat + 50% corn oil), and storage period (0, 15, 30, 45, 60, 75, and 90 days) arranged in a completely randomized design with two replications was used in the study. Some analyses were carried out only in fresh and storaged (90 days) samples. All data were subjected to variance analysis and differences between means were evaluated by Duncan's multiple range tests (significance P < 0.05) using SPSS 13 statistics software (SPSS, Inc., Chicago, IL, USA).

RESULTS AND DISCUSSION

The pH and TBARS values of fresh and storaged bologna-type sausages are shown in Table 1. The addition of broccoli caused an increase in the pH value. In contrast, the use of corn oil decreased the pH value. Similar results have been reported by Bloukas and Paneras[12] and Paneras and Bloukas[8] in low fat frankfurters produced with vegetable oils. TBARS values were higher in samples produced with animal fat than in samples with animal fat/corn oil. According to the results, the substitution of sheep tail fat with corn oil decreased TBARS value in bologna-type sausage. Bloukas and Paneras[12] determined that replacing animal fat with olive oil in low-fat frankfurters decreased TBA value. In samples produced with sheep tail fat, TBARS value decreased in the presence of 5% broccoli and increased in 10% broccoli. Similar results were observed in samples with sheep tail fat/corn oil. However, there were non-significant differences between both groups in terms of TBARS value. At the end of storage, TBARS value increased in both groups with animal fat and animal fat/corn oil. However, TBARS values of samples with sheep tail fat were higher than those of sheep tail fat/corn oil (Table 1). The low TBARS value observed in corn oil-containing sausage is mainly due to alpha- and gamma-tocopherols (vitamin E) in corn oil. Although high in unsaturated fatty acids, corn oil is stable due to its high amounts of vitamin E, which acts as a natural antioxidant to protect from oxidative rancidity.[20] During storage, pH value decreased slowly. At the end of storage, the pH value varied between 6.17 and 6.34 (Table 1). During the cold storage of bologna-type sausages, a reduction in pH value is attributed to the activity of lactic acid bacteria.[21]

Table 1 The effects of corn oil and broccoli on pH and TBARS values of fresh and storaged bologna-type sausages (values are means ±SD)

Substituting corn oil	Broccoli	Storage time (day)
		0		90
		pH	TBARS	pH	TBARS
100% sheep tail fat	0%	6.33 ± 0.01^c	6.36 ± 0.02^a	6.23 ± 0.02^bc	13.57 ± 0.80^a
	5%	6.43 ± 0.01^a	5.85 ± 0.18^a	6.26 ± 0.03^b	12.00 ± 0.31^ab
	10%	6.43 ± 0.02^a	6.37 ± 0.29^a	6.34 ± 0.06^a	13.61 ± 1.34^a
50% sheep tail fat + 50% corn oil	0%	6.26 ± 0.01^d	3.88 ± 0.04^b	6.17 ± 0.02^c	10.27 ± 0.99^b
	5%	6.37 ± 0.04^bc	3.26 ± 0.75^b	6.21 ± 0.03^bc	10.16 ± 0.73^b
	10%	6.38 ± 0.03^ab	3.85 ± 0.02^b	6.27 ± 0.01^ab	10.77 ± 1.01^b
a–d: Any two means in the same column having the same letters are not significantly different at p > 0.05; SD: standard deviation.

Substitution of sheep tail fat with corn oil had significant effects on the color parameters of bologna-type sausages (P < 0.01) (Table 2). With reference to control, the presence of corn oil caused an increase of lightness (L*), in contrast, the presence of corn oil reduced a* and b* values of samples. Paneras and Bloukas[8] have also reported higher L* values and lower a* and b* values internally for low-fat frankfurters with sunflower oil in comparison with high-fat control frankfurters. Özvural and Vural[7] found that the addition of interesterified vegetable oil and oil blends increased the L* and b* values of frankfurters.

Table 2 The effects of corn oil, broccoli, and storage period on color parameters of bologna-type sausages (values are means ±SD)

	L*	a*	b*
Substituting corn oil (O)
Sheep tail fat	69.03 ± 2.36^b	11.93 ± 1.32^a	12.51 ± 0.86^a
Sheep tail fat/corn oil	72.88 ± 2.33^a	11.58 ± 1.06^b	11.51 ± 0.77^b
Significance	**	**	**
Broccoli (%) (B)
0	72.39 ± 1.79^a	12.62 ± 0.68^c	11.50 ± 0.72^a
5	70.34 ± 3.06^b	11.97 ± 1.06^b	11.91 ± 0.75^b
10	70.12 ± 3.48^b	10.67 ± 0.92^a	12.62 ± 1.02^c
Significance	**	**	**
Storage period (S)
0 d	72.12 ± 2.61^ab	11.95 ± 1.13^bc	11.98 ± 0.73^ab
15 d	71.95 ± 2.79^ab	11.98 ± 1.34^ab	12.26 ± 0.95^ab
30 d	72.44 ± 2.91^a	11.62 ± 1.07^a	12.30 ± 0.96^b
45 d	69.16 ± 2.52^d	11.13 ± 1.17^d	11.20 ± 0.88^c
60 d	68.91 ± 2.74^d	11.61 ± 0.87^b	11.79 ± 0.98^b
75 d	71.54 ± 2.76^b	11.90 ± 1.44^ab	12.26 ± 0.96^ab
90 d	70.55 ± 2.94^c	12.10 ± 1.18^ab	12.27 ± 0.72^a
Significance	**	**	**
O×B	**	**	NS
O×S	**	*	NS
B×S	**	NS	NS
a–d: Any two means in the same column having the same letters in the same section are not significantly different at p > 0.05; SD: standard deviation; NS: not significant; *p < 0.05; **p < 0.01.

The use of broccoli decreased both L* and a* values. However, L* values of sausages were not affected by the percentage of broccoli (Table 2). In the present study, broccoli was added to an emulsion batch as a percentage of the weight of meat only, which resulted in dilution of myoglobin and, consequently, less red color. On the other hand, broccoli caused an increase in b* value. Storage time had significant effects (P < 0.01) on the color parameters of bologna-type sausages (Table 2). While the color of broccoli caused a decrease in a* and L* value, it increased b* value. Samples with 5 or 10% broccoli showed a higher L* value than samples without broccoli during the storage period (Fig. 1a). In the samples with corn oil, L* values were found to be higher in comparison with the samples with 100% animal fat. However, in samples with animal fat/corn oil, change in L* value during the storage was more than that in samples with 100% animal fat (Fig. 1b). The interaction of broccoli and storage period had a significant effect (P < 0.01) on the a* value of bologna-type sausages. In 10% broccoli level, lower values were detected in comparison to the other groups (0 and 5% broccoli) (Fig. 1c).

Figure 1 The effects of interactions between treatments on the color parameters of bologna-type sausage: (a) broccoli × storage period; (b) animal fat/corn oil × storage period; (c) broccoli × storage period. ♦: 0% broccoli; ■: 5% broccoli; ▲: 10% broccoli; •: 50% animal fat + 50% corn oil; ×: 100% animal fat.

Texture profile analysis indicated that, compared to the control samples, use of corn oil decreased hardness and increased gumminess, chewiness, cohesiveness, and springiness (Table 3). Bloukas and Paneras[12] reported that substitution of pork fat with olive oil caused a decrease in hardness and firmness of low-fat frankfurters with 10% protein. These results are in agreement with the results of Lurueña-Martínez et al.[22] who found that olive oil addition together with fat reduction caused a significant decrease in hardness. Sausages with animal fat had lower gumminess and chewiness than sausages with animal fat/corn oil. Similar results were detected for low-fat frankfurters containing olive oil (12–14% protein).[12] However, other authors have reported that olive oil addition reduced gumminess and chewiness.[22] An increase in springiness due to the addition of olive oil has been reported in other studies.[12,22] The use of broccoli had a significant effect (P < 0.01) on the hardness, gumminess, and chewiness (Table 3), with all parameters decreasing with an increase in broccoli content. The decreases of these textural characteristics were greater in samples with 10% broccoli. In contrast, the use of broccoli had no significant effect on the springiness and cohesiveness (P < 0.05). Storage time had a significant effect on hardness, springiness, and cohesiveness (P < 0.01). In general, the increase in storage time caused an increase in hardness of bologna-type sausages.

Table 3 The effects of corn oil, broccoli, and storage period on textural parameters of bologna-type sausages (values are means ±SD)

	Hardness	Gumminess	Chewiness	Springiness
	(N)	(N)	(Ncm)	(cm)	Cohesiveness
Substituting corn oil (O)
Sheep tail fat	62.33 ± 6.22^a	31.97 ± 3.91^a	26.86 ± 3.40^b	0.84 ± 0.02^b	0.51 ± 0.03^b
Sheep tail fat/corn oil	57.48 ± 5.20^b	35.34 ± 3.70^b	32.00 ± 3.50^a	0.91 ± 0.02^a	0.62 ± 0.05^a
Significance	**	**	**	**	**
Broccoli (%) (B)
0	62.87 ± 5.21^a	35.66 ± 2.66^a	31.33 ± 3.24^a	0.88 ± 0.04^a	0.57 ± 0.05^a
5	60.93 ± 6.44^b	33.92 ± 3.22^b	29.57 ± 3.37^b	0.87 ± 0.04^a	0.56 ± 0.05^a
10	55.92 ± 4.73^c	31.38 ± 5.06^c	27.40 ± 5.15^c	0.87 ± 0.04^a	0.56 ± 0.09^a
Significance	**	**	**	NS	NS
Storage time (S)
0 d	55.88 ± 4.93^d	33.53 ± 6.04^a	29.28 ± 6.08^a	0.87 ± 0.04^cd	0.60 ± 0.10^a
15 d	60.17 ± 6.57^bc	33.21 ± 3.72^a	28.59 ± 3.77^a	0.86 ± 0.04^d	0.56 ± 0.05^cd
30 d	57.95 ± 4.93^cd	32.98 ± 3.24^a	29.12 ± 3.59^a	0.88 ± 0.04^ab	0.57 ± 0.06^b
45 d	59.81 ± 5.36^bc	33.85 ± 3.11^a	29.58 ± 3.36^a	0.87 ± 0.03^bc	0.57 ± 0.05^bc
60 d	61.38 ± 6.42^ab	33.53 ± 4.26^a	29.14 ± 4.54^a	0.87 ± 0.04^cd	0.55 ± 0.05^d
75 d	61.38 ± 5.71^ab	33.79 ± 4.31^a	30.03 ± 4.59^a	0.89 ± 0.05^a	0.55 ± 0.08^cd
90 d	62.79 ± 7.20	34.71 ± 4.06^a	30.29 ± 3.91^a	0.87 ± 0.04^cd	0.56 ± 0.05^cd
Significance	**	NS	NS	**	**
O×B	NS	**	**	*	**
O×S	NS	NS	NS	NS	**
B×S	NS	*	*	NS	**
a–d: Any two means in the same column having the same letters in the same section are not significantly different at p > 0.05; SD: standard deviation; NS: not significant; *p < 0.05; **p < 0.01.

The interactions of broccoli × storage time and broccoli × animal fat/corn oil had very significant effects on the gumminess (P < 0.01). As seen in Fig. 2a, the samples containing 10% broccoli had lower values than other groups. In the 5% level, gumminess increased after the 60th day, and after the 75th day in the control (0% broccoli) (Fig. 2a). In samples with animal fat, a 10% broccoli level caused a significant decrease in gumminess (Fig. 2b). Similar results were also observed for chewiness. The interactions between treatments showed a similar trend with gumminess (Figs. 2c and 2d). Gumminess and chewiness behaved similarly to cohesiveness, mainly because it is the parameter that determines these secondary parameters. Cohesiveness reflects the internal resistance of food structure.[23] The interactions of broccoli × storage period and animal fat/corn oil × storage period had a significant effect (P < 0.01) on the change in cohesiveness (Figs. 2e and 2f). During the storage period, the lowest cohesiveness values were detected in the group with 10% broccoli (Fig. 2e). The bologna-type sausage produced with animal fat had lower cohesiveness than the sausages with corn oil (Fig. 2f). The decrease in cohesiveness of bologna-type sausage must be related to the loss of intramolecular attraction among ingredients with addition of broccoli and animal fat. It was stated that cohesiveness of sausage tended to decrease as fat content increased.[24,25] It has also been reported that the addition of vegetable oil to chicken meat sausage caused an improvement in textural properties of it.[26]

Figure 2 The effects of interactions between treatments on the textural parameters of bologna-type sausage: (a, c, e) broccoli × storage period; (b, d) animal fat/corn oil × broccoli; (f) animal fat/corn oil × storage period; ♦: 0% broccoli; ■: 5% broccoli; ▲: 10% broccoli; •: 50% animal fat + 50% corn oil; ×: 100% animal fat.

CONCLUSION

The use of corn oil and broccoli (max 10%) in bologna-type sausage has no negative effects on the pH and TBARS values. Corn oil has even decreased the oxidative rancidity and has positive effects on some textural characteristics. However, the use of broccoli has resulted in a decrease in L* and a* values and an increase in b* value. Sausage with broccoli and corn oil can be evaluated as an alternative functional food type.