Storage of beef burgers containing fructooligosaccharides as fat replacer and potassium chloride as replacing sodium chloride

Abstract

There was few studies using the simultaneous reduction of fat and sodium chloride, as well as the stability of the meat products with these reductions. This study aimed to evaluate the effects of fat and sodium chloride reduction in beef burgers during storage. For this, two treatments were produced: T1—without fat and sodium chloride reduction (control) and T2—with 50% fat reduction + 5% fructooligosaccharides and with the replacement of 50% of sodium chloride by potassium chloride. Physicochemical analysis and sensory acceptance were performed. According to results, the pH increased (p < 0.05) with 120 days. For the lipid oxidation, there was an interaction between treatments and storage. There was an increase in TBARS with storage for both treatments. T2 had the highest TBARS at 0, 30, and 60 days. For the color before cooking, there was a reduction in the redness (p < 0.05) with 90 days. After cooking, the lightness reduced at 90 days, while the redness increased at 90 days. However, the instrumental changes were not perceived by consumers. For the sensory acceptance, there was a reduction in the flavor, texture and overall liking with storage. However, despite the decline, the averages remained in the acceptance zone. The beef burgers were perceived as less juiciness and less salty after storage. Thus, the storage affects the physicochemical characteristics and sensory evaluation of beef burgers low-fat and low-sodium. The results reinforce the need for more studies with the storage of meat products with fat and sodium chloride reduced.

Introduction

The beef burger is an attractive meat product that is consumed by different age groups due to its low cost, easy preparation and sensory characteristics (Hautrive et al. 2019). However, this product has high fat, and sodium chloride (NaCl) amounts in its composition (Rios-Mera et al. 2019; Selani et al. 2016). Fat and sodium excessive intake are related to diseases, such as obesity, hyperlipidemia and hypertension (Barbosa et al. 2017; Zhou et al. 2019). Therefore, the reduction of these components becomes important to produce healthier foods.

Thus, the industry has a great challenge, since fat and NaCl influence the quality of meat products (Felisberto et al. 2015). NaCl contributes to conservation and affects quality characteristics such as texture, water holding capacity and flavor. Fat affects sensory (juiciness, texture and taste) and technological aspects (cooking loss, emulsion stability, water holding capacity, and rheological properties). The fat reduction provides several technological problems and leads to a decline in palatability, resulting in less accepted products (Ruusunen et al. 2005; Selani et al. 2016). Therefore, they are not easily reduced and replaced because this may result in less acceptable products.

Several strategies have been used to reduce fat and sodium in meat products. The fiber has been used in low-fat products (Bis-Souza et al. 2018), and among these fibers, the main are the fructooligosaccharides (FOS). FOS improve texture and water holding capacity (Pollonio 2011). For NaCl, the strategy most used in meat products is its partial replacement with other chloride salts. The most used is potassium chloride (KCl). Although, several studies have evaluated fat reduction (Abbasi et al. 2019; Bis-Souza et al. 2018; Carvalho et al. 2019; Guedes-Oliveira et al. 2016; Sousa et al. 2017) or of NaCl (Barbosa et al. 2017; Rios-Mera et al. 2019; Santos et al. 2015; Seganfredo et al. 2016; Stanley et al. 2017; Yotsuyanagi et al. 2016) in different meat products, few tested the simultaneous reduction of the two constituents.

The beef burger is a fresh meat product that has very distinct technological characteristics of other meat products, and the modification of the water holding capacity has a strong influence on the sensory characteristics and yield. Moreover, in the literature, there did no studies are using the simultaneous reduction of fat and sodium chloride, with the inclusion of FOS and KCl, as well as the stability of these meat products with these reductions. Therefore, the study aimed to evaluate the effects of fat and NaCl reduction on the physicochemical characteristics and the sensory acceptance of beef burgers during frozen storage for 120 days.

Experimental design

It was used an experimental design completely randomized factorial 2 × 5 (2 treatments and 5 storage times) with 5 replicates per treatment at each storage time. The treatments were: T1—control (without fat and NaCl reduction) and T2—with 50% fat reduction + 5% FOS and 50% NaCl + 50% KCl. The fat and NaCl formulation was defined in the previous experiment. The storage times were 0, 30, 60, 90, and 120 days.

The burgers were produced using beef meat (6.2% fat) and back fat and added of NaCl and KCl (Abrequim Química, São Paulo-SP, Brasil), and FOS, a short-chain fructooligosaccharide, composed of a mix of 1-kestose, nystose and 1-F-fructofuranosyl nystose and produced by enzymatic transfrutosylation reaction in sucrose residues (Fosvita, Vitafor, São Paulo, Brazil) (Table 1). The beef meat and back fat that was minced in a butcher grinder (Beccaro PB 09 LI, Rio Claro, Brazil). After, the ingredients NaCl and KCl, FOS, ice-water (10%), starch (0.1%), garlic (0.1%) and onion, in the form of powder (0.1%), monosodium glutamate (1%), antioxidant—sodium erythorbate (Sabor do Brasil, Ind. Com. Ltda, Brazil) (0.1%) and sodium tripolyphosphate (Ligatari, Exato, Ind. Com. Ltda, Brazil) (0.3%) were added and mixed. Then, the burgers of 50 g were shaped and packed under aerobic conditions in polyethylene bags. They were stored at − 20 °C. At different times (0, 30, 60, 90 and 120 days), the pH, water activity (Aw), lipid oxidation, color, and cooking characteristics analyses were performed. The microbiological analyses and sensory evaluation were done at 0 and 120 days. The color, cooking characteristics and sensory evaluations were made in the cooked product. The cooking was made in the electric grill (Suggar, Belo Horizonte, Brazil) until to reach 71 °C of internal temperature.

Table 1.

Formulations of beef burgers with and without reduced fat and sodium

	Treatments*
	T1	T2
Beef meat	93.00 g/100 g	96.50 g/100 g
Back fat	7.00 g/100 g	3.50 g/100 g
Sodium chloride	1.50 g/100 g	0.75 g/100 g
Potassium chloride	0.00 g/100 g	0.75 g/100 g
Fructooligosaccharides	0.00 g/100 g	5.00 g/100 g

*T1 – control (without fat and NaCl reduction); T2 – with 50% fat reduction + 5% fructooligosaccharides and 50% NaCl + 50% KCl)

Moreover, it was determined the composition data of lipid and sodium content of beef burgers treatments.

Microbiological analyses

The microbiological analyses were performed according to the established by the Brazilian Legislation (Brazilian Health Surveillance Agency) to verify the sanitary quality. The methods were determined according to Silva et al. (2017). Thus, the samples were investigated for thermotolerant coliforms, coagulase-positive Staphylococci, and sulfite-reducing clostridia. The presence of Salmonella sp. was determined using the dilution in lactose broth (KASVI, Brazil, K25-611,202). Thermotolerant coliforms were identified using the pour plate with Violet Red Bile Lactose Agar (KASVI, Brazil, K25-610,058). Coagulase-positive Staphylococci were identified by inoculating samples in Baird Parker Agar (KASVI, Brazil, K25-1100). enriched egg yolk and potassium tellurite (MERCK, Brazil, 232,213–1). Sulfite-reducing clostridia were counted by inoculating samples in SPS Agar (KASVI, Brazil, K25-610,207) in anaerobic jars.

Lipid and sodium content of treatments

The lipid content was determined according to the Soxhlet method and expressed by g/100 g (AOAC 1997). The sodium content was determined from the ashes of the beef burgers using a flame photometer (Analyzer model 910 M, São Paulo, Brazil). The result was expressed as mg of sodium/100 g.

pH

The pH was determined by digital pHmeter (Biotech, mPa-210, Piracicaba, Brasil) after homogenizing of 10 g raw sample in 100 mL distilled water.

Water activity

For the Aw, the raw burgers were measured using digital equipment (Aqualab, 4TE, Pullman, USA).

Lipid stability

The lipid oxidation was determined by the thiobarbituric acid reactive substances (TBARS) method (Cherian et al. 2002) with modifications. Then, 2 g of the raw sample was homogenated with 18 mL of trichloroacetic acid 7.5% (Sorensen and Jorgensen 1996), and and 50 μL of hydroxytoluene butylate 4.5% for 1 min. The homogenate was centrifuged (Solab SL-700, Piracicaba, Brazil) at 3500 rpm for 3 min. The supernatant was filtered in Whatman no 1. After, 2 mL of the filtrate was mixed with 2 mL of 20 mM aqueous 2-thiobarbituric acid (TBA), heated at 90 °C in a thermoregulated bath (Solab, SL-150/10, Piracicaba, Brazil) for 30 min. The color provided by the reaction between the malonaldehyde and TBA was measured by a spectrophotometer (Biospectro, SP-22, Curitiba, Brazil) at 531 nm. The TBARS values were calculated from a standard curve, using 1,1,3,3‐tetraethoxypropane. The number of TBARS in the samples was expressed as mg malonaldehyde per kg beef burgers.

Cooking quality

The cooking quality was determined by cooking loss and diameter reduction, according to Angiolillo et al. (2015). Thus, before cooking the beef burgers were weighted and its diameter measured. The cooking was done in the electric grill (Suggar, Belo Horizonte, Brazil) until to reach 71 °C of internal temperature. After cooking, the beef burgers were weighed and its diameter measured.

Instrumental color

The instrumental color was determined by the spectrophotometer (Minolta, CM 2300D, Tokyo, Japão) using the CIE system (L* and a*). The measurements were made on the surface of burgers before and after cooking.

Sensory acceptance

This research was approved by the Research Ethics Committee of the Federal University of Maranhão, Brazil (CAAE 55988116.9.0000.5087). The sensory acceptance was performed by 60 consumers (60% women and 40% men) who were selected by like and consumed burgers. The beef burgers were cooked using the electric grill (Sugar, Belo Horizonte, Brazil) after taking out of the freezer. The samples were baked for 4 min when the internal temperature reached 71 °C. The samples (20 g) were given in a monadic sequential order in standard sensory booths.

The consumer acceptance measured for hedonic scale evaluated color, appearance, aroma, flavor, texture, and overall liking attributes. The scale ranged from 1 (dislike extremely) to 9 (like extremely). The juiciness and salty taste were evaluated using a just-about-right (JAR) scale. The scale ranged from 1 (Much too weak than JAR) to 9 (Much too strong than JAR) (Stone and Sidel 2004). The purchase intention was also evaluated by the use of a 5 point scale, ranging from 1 (I certainly would not buy) to (I would certainly buy).

Data analysis

The physicochemical analysis data were examined using ANOVA with a factorial design, which included the effects of treatment, storage time, and interaction between treatment and storage. If a significant interaction was verified, further analysis was used to evaluate the impact of each factor on the others. The Student–Newman–Keuls test was used for the mean comparison (p < 0.05).

For the hedonic scale data, the treatments and storage were considered as a fixed source of variation and the consumer as a random effect. The mean were analyzed by the non-parametric Friedman test (p < 0.05). Moreover, the principal component analysis was performed to visualize how the treatments were affected by the flavor attribute. All statistical analyses were performed using XLSTAT software (Addinsoft, Paris, France).

For the juiciness and salty taste, evaluated by JAR, histograms were performed with the percentages from 1 to 4 was named “not enough region.” The percentage at score 5 was called “JAR region” and the percentages from 6 to 9 of “too much”.

For the purchase intention, the histograms were also divided into three regions: percentages of 1 and 2 were named “I would buy it”, percentage at score 3 was called “Maybe I would but it” and the percentages of 4 and 5 of “I would not buy it”.

Microbiological analyses

The microbiological analyses (data not shown) revealed that all the treatments were within limits established by Brazilian Legislation (Brazilian Health Surveillance Agency). The microbial counts were < 100 CFU g⁻¹ for thermotolerant coliforms, < 10 CFU g⁻¹ of sulfite-reducing clostridia, < 100 CFU g⁻¹ of Coagulase-Positive Staphylococci, and absence of Salmonella in 25 g. According to these results, all the treatments of low-fat beef burger and control were safe for consumption from a microbiological standpoint.

Lipid and sodium content of formulations

The lipid contents of T1 and T2 were 6.5 g/100 g and 4.0 g/100 g, respectively. Thus, the back-fat reduction of 50%, provided the fat reduction of 39% of beef burgers. Other authors (Faria et al. 2015; Sousa et al. 2017) reported reductions in lipid content, with percentages between 21 and 42%, when half reduced the fat content of the formulation in products such as bologna and frankfurters sausages, respectively. The variation in the values is a consequence of the amount of fat in meat cuts.

The sodium contents of T1 and T2 were 583 mg/100 g and 350 mg/100 g, respectively. The 50% reduction in the NaCl generated a decrease of 40% in the sodium content of the beef burgers. Carraro et al. (2012) obtained sodium reduction of 31.5% in bologna sausages when the NaCl was reduced by half. The variation in the values is a consequence of the sodium provided by other ingredients.

pH, water activity (Aw) and lipid stability of stored beef burgers

For pH, there was no interaction (p > 0.05) between treatments and storage of beef burgers. Also, no significant difference was observed in the treatments. Thus, the fat and sodium chloride removal with FOS and potassium chloride inclusion did not influence the beef burgers pH. However, there was an effect (p < 0.05) of storage time (Table 2). Thus, the storage provided an increase in pH, and the beef burgers stored for 120 days had the highest values. This pH increase could indicate a reduction in product stability during storage. However, the microbiological analyses (data not shown) showed the absence of micro-organisms. Therefore, the microbial safety was maintained with 120 days of frozen storage, guaranteeing consumption conditions.

Table 2.

pH, water activity (Aw) and TBARS values (mg malonaldehyde/kg) and cooking quality of beef burgers with and without reduced fat and sodium stored for 120 days at − 20 °C. (n = 5)

Treatments*	Storage time (days)					Mean
	0	30	60	90	120
pH
T1	5.95 ± 0.11	6.20 ± 0.10	6.29 ± 0.04	6.13 ± 0.05	6.59 ± 0.07	6.23 ± 0.23A
T2	5.99 ± 0.12	6.10 ± 0.01	6.28 ± 0.08	6.13 ± 0.02	6.41 ± 0.31	6.18 ± 0.20A
Mean	5.97 ± 0.11d	6.15 ± 0.08c	6.28 ± 0.06b	6.13 ± 0.03c	6.50 ± 0.23a
Aw
T1	0.98 ± 0.00	0.98 ± 0.00	0.98 ± 0.00	0.98 ± 0.00	0.98 ± 0.00	0.98 ± 0.00A
T2	0.98 ± 0.00	0.98 ± 0.00	0.98 ± 0.00	0.98 ± 0.00	0.98 ± 0.00	0.98 ± 0.00A
Mean	0.98 ± 0.00a	0.98 ± 0.00a	0.98 ± 0.00a	0.98 ± 0.00a	0.98 ± 0.00a
TBARS
T1	0.15 ± 0.03cB	0.20 ± 0.02cB	0.39 ± 0.05bB	0.35 ± 0.04bA	0.48 ± 0.10aA	0.31 ± 0.13
T2	0.39 ± 0.02bA	0.29 ± 0.02cA	0.46 ± 0.03aA	0.40 ± 0.02bA	0.49 ± 0.04aA	0.41 ± 0.07
Mean	0.27 ± 0.13	0.24 ± 0.05	0.43 ± 0.06	0.37 ± 0.04	0.49 ± 0.07
Cooking loss (%)
T1	34.14 ± 5.66	35.46 ± 5.75	38.45 ± 5.11	35.29 ± 4.30	34.25 ± 2.88	35.52 ± 4.71A
T2	41.52 ± 10.90	35.0 ± 9.17	45.06 ± 5.54	36.76 ± 6.68	29.70 ± 10.36	37.65 ± 9.67A
Mean	37.83 ± 9.07ª	35.33 ± 7.22ª	41.76 ± 6.11ª	36.02 ± 5.35ª	31.98 ± 7.56ª
Diameter reduction (%)
T1	20.57 ± 6.22	21.64 ± 6.01	20.12 ± 3.38	16.94 ± 4.52	16.78 ± 7.49	19.21 ± 5.59A
T2	19.10 ± 4.80	21.94 ± 6.04	22.48 ± 2.03	14.51 ± 6.38	16.10 ± 4.65	18.82 ± 5.59A
Mean	19.84 ± 5.29ª	21.79 ± 5.68ª	21.30 ± 2.90ª	15.73 ± 5.37ª	16.44 ± 5.89ª

*T1 – control (without fat and NaCl reduction); T2 – with 50% fat reduction + 5% fructooligosaccharides and 50% NaCl + 50% KCl). Means with different lowercase letters in the rows and capitals letters in the columns differ by the Student–Newman–Keuls test (p < 0.05).

For the treatment effect, similar results were reported by Angiolillo et al. (2015) who did not observe changes in pH when included inulin, FOS, or oat bran in beef burgers. The same result also was reported by Cáceres et al. (2004) using FOS as a fat replacer in cooked sausages. Other authors (Carvalho et al. 2019; Sousa et al. 2017) also observed no changes in pH with fat reduction and the use of different substitutes. Some authors found that the replacement of sodium chloride by potassium chloride or other salts did not affect the pH of products such as fermented sausage (Campagnol et al. 2012) and pork sausage patties (Stanley et al. 2017).

For the storage, Yotsuyanagi et al. (2016) also observed an increase in pH during storage of frankfurters produced with potassium chloride in replacement to sodium chloride. An increase in pH after 90 days of storage was also reported by Hautrive et al. (2019) in hamburgers containing chitosan and golden flaxseed flour as fat substitutes. These results are in agreement with those obtained in the present study. Al-Juhaimi et al. (2019) also observed increased on the pH of beef burgers with 21 days and attributed to the deamination of proteins. Thus, the results obtained herein is due to the modifications in the proteins that occur during storage.

However, Triki et al. (2017) observed pH reduction in meat products when the sodium chloride was replaced by a mixture of salts (KCl, CaCl_2, and MgCl₂) or commercial replacer based on seaweed extracts. These authors attributed the pH reduction to the organic acids production due to the lactic acid bacteria growth. Thus, the results obtained herein are positive because it did not observe microbial growth.

For water activity, there was no significant interaction (p > 0.05) among treatments and storage times. This parameter also there was not ranged (p > 0.05) with the treatments and storage time (Table 2). Thus, the fat reduction with FOS inclusion, sodium chloride substitution by potassium chloride, and storage did not influence the Aw. This result is positive since the Aw maintenance activity contributes to the conservation characteristic of the product.

Cáceres et al. (2004), using FOS as a fat substitute in cooked sausages also did not observe the range of water activity. For sodium chloride replacement, some authors (Campagnol et al. 2012; Santos et al. 2015) also not reported an effect of the potassium chloride alone or mixture with other salts in the Aw. These results are opposites of those reported by Barbosa et al. (2017) that obtained an increase in Aw in goat kafta by replacing 50% of the sodium chloride by potassium chloride. These authors attributed this change to the higher sodium chloride capacity in reducing Aw due to its greater dehydrating power with potassium chloride. However, according to Seganfredo et al. (2016), these differences in Aw behavior may be related to food composition. For the storage, Candogan and Kolsarici (2003) also reported that storage time did not affect Aw in beef frankfurters formulated with carrageenan or carrageenan with pectin as a fat replacer.

For the lipid stability, there was significant interaction (p < 0.05) between treatments and storage times of beef burgers for TBARS values (Table 2), indicating different responses of treatments over the storage for this variable. Thus, the TBARS values were evaluated each treatment over time storage separately. With the dismemberment of the interaction, T2 had higher (p < 0.05) TBARS value up to 60 days. At 90 and 120 days, there was no difference (p > 0.05) between treatments for the variable. For the storage time, in both treatments, there was an increase in TBARS values between 0 and 120 days. The lipid oxidation provided the rancidity development causing a quality reduction of meat products during storage (Jin et al. 2018). In the present study, despite the observed increase, all the values found are below 1.0 mg of malonaldehyde/kg of beef burger. This value is considered the threshold that can indicate loss of sensory quality in foods (Rather et al. 2016).

An increase in TBARS values in meat products with fat or sodium chloride reduction was also reported by some authors. Hautrive et al. (2019), replacing the fat by golden flaxseed flour (wholemeal and defatted) in hamburgers, observed lipid oxidation increase. These authors reported that the highest TBARS values were in the product with the whole meal. Moreover, these authors noted an increase in TBARS values with storage. Abbasi et al. (2019) also reported increase in lipid oxidation during 28 days in emulsion type sausage when used tragacanth gum as partial replacement of fat. In products with sodium chloride substitution, Stanley et al. (2017) achieved an increase in TBARS values in pork sausage patties during storage when potassium chloride was used as a substitute. A TBARS increase was also reported by Horita et al. (2011) during the storage of reduced-fat mortadella and using a blend of CaCl₂, MgCl_2, and potassium chloride as a partial sodium chloride substitute. Jin et al. (2018), observed higher TBARS values in fat-reduced sausages with partial replacing sodium chloride with other chloride salts after 21 and 35 days. In the present study, this increased also occurred.

Cooking quality of stored beef burgers

For cooking quality measurements, there was no interaction (p > 0.05) between treatments and storage times. There was also no influence on treatment or storage time on the values of these variables (Table 2). Thus, the fat reduction with FOS inclusion, sodium chloride substitution by KCl, and storage did not influence the cooking quality. In low-sodium products, increased cooking loss is one of the main concerns (Ruusunen et al. 2005). This occurs due to sodium contributes to the water retention capacity of the meat. Similarly, fat reduction without adequate replacement may result in decreased yield and higher losses (Pollonio 2011). Therefore, the results obtained in the present study indicate that the cooking quality of the fat and sodium chloride reduced beef burgers was not altered. These products had similar behavior to that of the conventional beef burgers (control) throughout the frozen storage.

These results differ from studies that had reduced cooking losses (Selani et al. 2016; Turhan et al. 2005) in fat-reduced beef burgers added with different substitutes. Moreover, different from the present study, the authors mentioned above observed a smaller shrinkage of the beef burgers during cooking, that is, the diameter reduction was lower in treatments with the substitute. Although the diameter reduction has not changed (p > 0.05) in the present study among the treatments, the values obtained (15.73–21.94%) are close to those reported by Carvalho et al. (2019) 16.85–25.57%), Selani et al. (2016) (18.79—27.58%) and Turhan et al. (2005) (20.11—27.06%) by replacing the fat in hamburger with hydrated wheat fiber, pineapple byproduct, and canola oil, and hazelnut pellicle, respectively.

Different results are also cited for products with simultaneous fat and sodium chloride reduction. Ruusunen et al. (2005) found that beef burgers with higher sodium concentration had lower cooking losses, while higher losses were observed in beef burgers with higher fat content. Felisberto et al. (2015) evaluated the effect of prebiotic fibers (inulin, FOS, polydextrose, and resistant starch) in reduced-sodium and low-fat meat emulsions. These authors observed higher cooking losses in formulations with inulin and polydextrose. An increase in cooking losses was also reported by Jiménez-Colmenero et al. (2010) in reduced/low-fat, low-salt frankfurters added of konjac and seaweed. In the studies mentioned above, the reduction of NaCl was not accompanied by substitution. Thus, the lack of variation between treatments in the present study can be resultant of KCl that prevents changes in cooking characteristics.

The fact can be confirmed by the results of Barbosa et al. (2017) in goat kafta with sodium chloride reduction. These authors did not obtain the difference in cooking losses between the treatments with low sodium added of potassium chloride when compared to control. The authors suggested that potassium chloride in low concentrations has a high capacity to extract myofibrillar proteins, stimulating the water retention capacity. Therefore, the effect of reduction cooking quality did not observe herein using FOS and potassium chloride, evidencing the is viable their use in beef burgers.

Instrumental color of stored beef burgers

Several authors have studied changes in color in meat products with fat and sodium chloride reduction. However, there are few kinds of research with both declines in the same product. No significant interaction between treatments and storage times for color components (L* and a*) was observed before or after cooking. Moreover, there was no influence (p > 0.05) of the treatment on the color component L* (lightness) of raw or cooked beef burgers (Table 3). Therefore, the fat reduction with FOS inclusion and sodium chloride substitution by potassium chloride did not influence this color parameter. For the storage time, it also there was not influenced (p > 0.05) in the lightness values before cooking. However, the cooked beef burgers had a reduction (p < 0.05) of lightness at 90 days when compared with 0 days. Thus, the result indicates that the beef burgers were darker than at the beginning of storage.

Table 3.

Color components (L* and a*) of beef burgers with and without reduced fat and sodium stored for 120 days at frozen storage (− 20 °C). (n = 5)

Treatments*	Storage time (days)					Mean
	0	30	60	90	120
L* (before cooking)
T1	43.60 ± 4.84	41.37 ± 1.70	40.53 ± 2.16	43.75 ± 2.25	41.36 ± 2.24	42.12 ± 2.94A
T2	41.74 ± 2.92	39.19 ± 2.11	41.03 ± 2.95	40.06 ± 1.53	40.64 ± 2.54	40.53 ± 2.42A
Mean	42.67 ± 3.90ª	40.28 ± 2.14ª	40.78 ± 2.45ª	41.90 ± 2.66ª	41.00 ± 2.29ª
a* (before cooking)
T1	12.99 ± 1.21	12.74 ± 1.28	10.08 ± 1.94	6.66 ± 0.45	7.71 ± 0.74	10.04 ± 2.85A
T2	13.60 ± 2.45	12.66 ± 2.00	9.45 ± 1.49	8.55 ± 0.72	8.92 ± 0.62	10.63 ± 2.58A
Mean	13.29 ± 1.85ª	12.70 ± 1.58ª	9.77 ± 1.67b	7.61 ± 1.14c	8.32 ± 0.90c
L* (after cooking)
T1	45.74 ± 3.71	47.02 ± 0.93	44.13 ± 4.58	42.55 ± 3.03	42.37 ± 5.65	44.36 ± 4.02A
T2	45.65 ± 1.72	45.21 ± 1.33	40.79 ± 3.03	39.57 ± 5.70	42.75 ± 2.19	42.79 ± 3.80A
Mean	45.69 ± 2.73ª	46.12 ± 1.44ª	42.46 ± 4.06ab	41.06 ± 4.58b	42.56 ± 4.04ab
a* (after cooking)
T1	4.39 ± 0.93	5.08 ± 1.23	5.49 ± 0.63	6.40 ± 0.98	6.28 ± 1.09	5.53 ± 1.18A
T2	4.50 ± 0.82	5.22 ± 0.23	6.02 ± 1.14	7.60 ± 2.46	6.67 ± 0.85	6.00 ± 1.64A
Mean	4.45 ± 0.83c	5.15 ± 0.85bc	5.76 ± 0.91ab	7.00 ± 1.88ª	6.48 ± 0.94ª

A similar result was obtained by Gök et al. (2011) that did not observe the influence on the lightness of the raw and cooked meat burgers when used ground poppy seed as a fat replacer. A decrease in brightness was observed by other researchers with fat reduction (Jiménez-Colmenero et al. 2010; Sousa et al. 2017) or sodium chloride reduction (Barbosa et al. 2017; Seganfredo et al., 2016) in meat products. The fat removal is commonly associated with reduced brightness, making the products darker (Jiménez-Colmenero et al. 2010). In the present study, the variation lack between treatments is resultant of interaction of FOS and KCl avoiding lightness loss.

During the storage, a lightness decrease was observed by Hautrive et al. (2019) in fat-reduced hamburgers using chitosan and golden flaxseed flour as replacements. Stanley et al. (2017) also found this result in pork sausage patties with partial sodium chloride replacement by potassium chloride. In the present study, a lightness reduction was also observed with storage.

For the color component a* (redness), there was no influence (p > 0.05) of the treatment before or after cooking (Table 3). However, the storage time provided in redness a reduction in the raw and an increase in cooked beef burgers starting with 60 days of storage. The decline in redness may be related to the pigment oxidation during frozen storage. The redness is essential to evaluate the coloring of meat and meat products. Its decrease may indicate product discoloration and may affect consumer acceptance (Kim et al. 2013).

For the treatments, similar to the present study, Gök et al. (2011) did not observe the influence of the ground poppy seed as a fat replacer in the redness of the burgers before and after cooking. The same was reported by Sousa et al. (2017) by frankfurter-type sausages with partial replacement of fat by hydrolyzed collagen in frankfurter-type sausages. Other authors said that there were no changes in the redness and yellowness in fat-reduced (Carvalho et al. 2019) or low sodium chloride meat products (Delgado-Pando et al. 2018). In products with simultaneous fat and sodium chloride reduction, some authors reported the influence of the treatments on the redness and yellowness, which differs from that observed in the present study. Felisberto et al. (2015) found changes in the redness when used prebiotic ingredients in reduced-sodium and low-fat meat emulsions. Jin et al. (2018) noted that the redness increased with the sodium chloride substitution with other chloride salts in sausages. Similarly to the lightness, in the present study, the variation lack between treatments can be resultant of interaction of FOS and KCl avoiding redness loss.

For the storage, Hautrive et al. (2019) observed redness reduction in hamburgers containing chitosan and golden flaxseed flour as fat substitutes. This results in agreement with the present study for burgers before cooking. This reduction was also reported by Stanley et al. (2017) during the storage of pork sausage patties in which sodium chloride reduction and replacement with KCl. As observed for burgers after cooking, Jin et al. (2018) obtained an increase in redness values during the storage of fat-reduced sausages and formulated with a blend of chloride salts.

Sensory acceptance evaluation of stored beef burgers

The sensory evaluation was performed on days 0 and 120 of storage (Table 4). In the hedonic scale, all sensory attributes were positively scored, with a rating between “like slightly” and “like extremely” (6.88 and 8.05). Thus, it is possible to conclude that beef burgers had good acceptance by consumers. It is important to emphasize the consumer profile (data not shown) indicated that most of the panelists were not in the habit of consuming products with reduced fat and sodium chloride and even, so the acceptance of beef burgers was high.

Table 4.

Sensory acceptance of beef burgers with and without reduced fat and sodium stored for 120 days at − 20 °C. (n = 5)

	T1(0)	T1(120)	T2(0)	T2(120)
Color	7.23 ± 1.64ª	7.38 ± 1.47ª	7.35 ± 1.61ª	7.45 ± 1.43ª
Appearance	7.10 ± 1.59ª	7.42 ± 1.33ª	7.30 ± 1.63ª	7.40 ± 1.52ª
Aroma	7.32 ± 1.72ª	7.17 ± 1.73ª	7.13 ± 2.11ª	7.02 ± 1.75ª
Flavor	8.05 ± 1.42ª	6.92 ± 1.94b	7.42 ± 1.90ab	6.88 ± 1.72b
Texture	7.83 ± 1.47ª	7.07 ± 1.82b	7.18 ± 2.06ab	7.03 ± 1.57b
Overall liking	7.78 ± 1.35ª	7.20 ± 1.41ab	7.25 ± 1.94ab	7.07 ± 1.48b

T1 – control (without fat and NaCl reduction); T2 – with 50% fat reduction + 5% fructooligosaccharides and 50% NaCl + 50% KCl). T1(0) and T2(0)—0 day; T1(120) and T2(120)—120 days. Means with different letters in the rows differ by the Friedman test (p < 0.05).

Similar results were obtained by Guedes-Oliveira et al. (2016) that reported scores between 7.5 and 8.1 for the sensory attributes in chicken patties using washed cashew apple fiber (Anacardium occidentale L.) as a fat replacer. However, lower values were observed in other studies, such as those reported by Turhan et al. (2005) (3.56–7.35), Carvalho et al. (2019) (5.82–7.63) and Gök et al. (2011) (5.4–8.4) in hamburgers, when different substitutes were used. In products with sodium chloride reduction, the lower mean was also obtained by Carraro et al. (2012) (4.85–5.80) and Horita et al. (2011) (4.55–6.88) in bologna sausage.

There was no significant difference (p > 0.05) in color acceptance, appearance, and aroma attributes (Table 4). Therefore, the fat reduction with FOS inclusion, sodium chloride substitution by potassium chloride and storage did not influence these attributes. This result is satisfactory because color and appearance are the characteristics that most affect the consumer at the time of purchase. Moreover, the color changes detected by the instrumental evaluation (Table 3) were not perceived by the consumers. A similar result was reported by Cáceres et al. (2004) when evaluated the FOS as a fat substitute. These authors verified that the differences observed for instrumental color were not confirmed by sensory evaluation. Other authors did not find changes in color acceptance (Cáceres et al. 2004; Carraro et al. 2012; Jin et al. 2018; Seganfredo et al. 2016), appearance (Guedes-Oliveira et al. 2016; Horita et al. 2011) and aroma (Abbasi et al. 2019; Carvalho et al. 2019) of meat products with reduced-fat or sodium chloride. Thus, the results of these authors confirm the acceptance of these attributes obtained in the present study.

For flavor, texture, and overall liking, when the treatments were compared in the same days (T1 and T2 at 0 days and T1 and T2 at 120 days) there was no difference (p > 0.05) observed. However, there was a reduction in the flavor and texture acceptance of the T1 (control) with the storage [T1 (0) and T1 (120)] (Table 4), since the average for these attributes with 120 days was lower than that of day 0. However, for the overall liking, there was no difference (p > 0.05) between the beginning and at the end of storage. For the T2, the flavor, texture and overall liking were not affected by storage, since there was not differ (p > 0.05) between days 0 and 120. Thus, the storage had more effect on these sensorial characteristics in the control treatment (T1). However, despite the observed reduction, the scores remained in the acceptance zone of the hedonic scale, which includes the values between 6 and 9.

The Principal component analysis (PCA) was applied in the flavor data. The PCA1 (F1) explained 55.09% and the PCA2 (F2) 23.56% (Fig. 1). Thus, the sum of the two PCA is 78.65%, being high than 70%. This percentage is sufficient to represent the dispersion of the formulations, explaining the variation of the data. In Fig. 1, each point represents the correlations between the consumer acceptance data with the two principal components. In the graph, it is possible to observe the presence of two distinct groups, being 1 formed by T1 (0) and T2 (0) in quadrant 1 and the other by T1 (120) and T2 (120) in quadrant 4. Thus, these data confirm those of Table 4, with the flavor acceptance ranging during storage, but it did not range between treatments. Moreover, according to CPA, the beef burgers of T1 (0) could be chosen as the preferred for having the highest concentration of panelists around it.

Fig. 1.

Representation for the flavor acceptance in the first and second Principal component analysis of beef burgers with and without reduced fat and sodium stored for 120 days at − 20 °C.

T1 – control (without fat and NaCl reduction); T2 – with 50% fat reduction + 5% fructooligosaccharides and 50% NaCl + 50% KCl)

Different results were reported by other studies in which sensory acceptance decreased with fat and sodium chloride reduction. Hautrive et al. (2019), using chitosan as a fat replacer in hamburgers, had less flavor and overall liking acceptance. Horita et al. (2011) reported a reduction of the flavor acceptance when sodium chloride was replaced by other chloride salts in reduced fat mortadella. Santos et al. (2015) obtained a decrease in texture acceptance when 50% of sodium chloride of the fermented sausage was replaced by potassium chloride or CaCl₂ or a mixture of both. For the storage, Jin et al. (2018) observed lower acceptance of overall liking in reduced fat sausages when the sodium chloride was replaced by a blend of KCl and CaCl₂ or by a combination of KCl, CaCl_2, and MgCl₂.

The just-about-right (JAR) was used for the juiciness and the salty taste of beef burgers. The percentage of "JAR region” for juiciness ranged from 38.33 to 66.67% (Fig. 2a). The highest percentage was observed for the control (T1) at the storage beginning (day 0). Moreover, in Fig. 2a, it is observed that the storage reduced the JAR zone percentage for the two treatments. This reduction was 27 and 30% for T1 and T2, respectively. For both treatments, there was an increase in the percentage in the “not enough zone”, mainly for T2 (43.33%). Juiciness is a texture characteristic, and its reduction may have contributed to the reduction of texture acceptance of beef burgers (Table 4) since T1 and T2 treatments at 120 days had lower acceptance than T1 at the storage beginning (0 days).

Fig. 2.

The “not enough,” “just-about-right” and “too much” regions for the juiciness (a) and salty taste (b), and purchase intent (c) of beef burgers with and without reduced fat and sodium stored for 120 days at − 20 °C.

T1 – control (without fat and NaCl reduction); T2 – with 50% fat reduction + 5% fructooligosaccharides and 50% NaCl + 50% KCl)

For the salty taste (Fig. 2b), the JAR zone percentages ranged from 50.00 to 66.67%. Similar, the juiciness, the highest rate was observed for T1 at the storage beginning (day 0). The storage provided a reduction in the JAR zone percentage that it was approximately 12% for both treatments. The storage had lower interference in the salty taste perception. T2 had the highest rate (36.67%) in the "not enough zone" at the beginning and the end of storage (Fig. 2b).

This result may be related to the lower flavor acceptance of T2 (Table 4). Yotsuyanagi et al. (2016) reported percentages in JAR zone for salty taste ranging from 52 to 65% in frankfurters sodium chloride reduced. The percentage is similar to those obtained in herein. Moreover, similar to the present study, the treatment with lower sodium chloride concentration had the lowest rate.

Santos et al. (2015) evaluated the salty taste of low-sodium fermented sausages. These authors reported a lower percentage in the “JAR zone" and a higher percentage in the "not enough zone" when the sodium was partially replaced with KCl and/or CaCl₂. The same was observed by Stanley et al. (2017) in pork sausage patties with sodium replacement by KCl. These authors observed that the percentage in the "JAR zone" of the treatments with reduction was lower when compared to control, indicating that the replacement affected the perception of the salty taste, confirming what was observed for the herein for the beef burgers.

The purchase intent of the beef burgers had a reduction with the storage (Fig. 2c). This reduction was higher for T1 (27%) compared to T2 (14%). The highest percentage in this zone (78.33%) was observed for T1 treatment at the storage beginning (day 0) (Fig. 2c). Similar results were found by Yotsuyanagi et al. (2016) in frankfurters. These authors had the highest percentage of purchase intent in the treatments with high sodium chloride concentration.

Conclusion

The storage was the main factor that influenced the physicochemical characteristics and the sensory acceptance of beef burgers. The fat and NaCl reduction with FOS and KCl inclusion had less influence on the physicochemical characteristics.

During storage, there was an increase in pH and lipid oxidation, although these remained within limits accepted. There was a reduction in the lightness in the cooked product and redness of the raw product. However, the instrumental changes were not perceived by consumers.

For sensory acceptance, there was a reduction in the flavor, texture, and overall liking. However, despite the decrease observed, the averages remained in the acceptance zone. The beef burgers were perceived as less juiciness, less salty and with lesser purchase intention after storage. Thus, the results reinforce the need for more studies with the storage of meat products with fat and NaCl reduced. Moreover, it is essential the search for additional strategies to minimize the changes caused by substitutes and storage.