Technological and nutritional aspects of salted food bars manufactured with different binding agents

Salted food bars are an alternative in order to reach sugar reduction consumption. The challenge to create this type of bar is to substitute sweet binding agents. This study intended to evaluate the technological and nutritional aspects of salted food bars elaborated with Research, Society and Development, v. 9, n. 11, e8269119958, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i11.9958 2 different concentrations of binding agents (modified starch, hydrolyzed collagen and acacia gum) with low caloric value. The basic ingredients (oats, linseed, soybean, sesame, quinoa, dehydrated tomato, seasonings such as garlic, onion and dehydrated parsley and NaCl) were added to the binding agent solutions. The food bars were analyzed chemically, physically and physicochemically. The results demonstrated that the three binding agents tested presented technical viability of agglutination of the ingredients. The food bars presented high content of dietary fiber, low caloric value, and high mineral (Fe, Zn, Mn and Mg) contents. Cereal bars produced with acacia gum presented higher texture values related to the chewability parameter, which had a positive influence.


Introduction
Cereal bars have gained much popularity in the market. They are widely consumed as a source of protein and bioactive compounds, providing energy in a practical and healthy way for every day (Kaur, Ahluwalia, Sachdev & Kaur, 2018). Commercialization of sweet food bars is common, since sugars act as binder and sweetener. In cereal bars sugar has technological function. The glucose syrup, honey, molasses and brown sugar act as binding agents. These binding agents promote the aggregation of the dry ingredients, help shape the dough and confer high caloric value (Pallavi, Chetana, Ravi & Reddy, 2015).
Despite the technological and sensory functions of sugar in cereal bars, consumers have become more aware of the problems caused by excessive sugar consumption (Pallavi et al., 2015). The high consumption of sugar causes dental cavities, diabetes mellitus, cardiovascular diseases, obesity and hypertension (Manickavasagan, Mathew, Al-Attabi & Al-Zakwan, 2013). Therefore, the demand for reduced sugar supply or sugar free products have increased (Pallavi et al., 2015). Sugar substitutes in cereal bars may have low sensory acceptance and lower shelf life (Su-Ah, Ahmed & Eun, 2017), making the development of these products a challenge for the food industry. Thus, research on new binding agents is important to reduce the caloric content of cereal bars, making these snacks healthier with higher sensorial acceptance.
Salted food bars are an alternative in order to reach sugar reduction goals. The challenge to create this type of bar is to substitute sweet binding agents. These agents aggregate or agglutinate all the basic or dry ingredients, and may be replaced by other agents that provide compact and cohesive dough with lower caloric value (Srebernich, Gonçalves, Research, Society andDevelopment, v. 9, n. 11, e8269119958, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i11.9958 4 Ormenese & Ruffi, 2016). To produce salted food bars it is necessary to find ingredients that have the same technological properties as sugar and can interfere positively on the flavor and texture, while having good sensory acceptance by the consumer. An alternative is the use of hydrocolloids, which are extensively applied to restructure foods with low sugar content (Saha & Bhattacharya, 2010).
Hydrocolloids are used in the food industry because they have properties of thickening and gelling agents and low caloric value (Mikuš, Valík & Dodok, 2011). They are able to modify the rheology of food because of their ability to bind with water. This unique property of water uptake is able to eliminate free water, providing unique texture and consistency according to the concentration utilized, stabilizing the shelf life of the food (Saha & Bhattacharya, 2010).
The starch properties of gelling, thickening and aqueous solubility are the preferable characteristics for food processing (Mahmood et al., 2017). The use of modified starch by the food industries is an alternative which has been applied for some time with the purpose of overcoming one or more limitations of common starch (Zhu, 2018) in order to obtain food products with several texture sensations.
Acacia gum (gum arabic) is characterized as soluble fiber that provides adhesive properties, in addition to good stability during storage, decreasing the hygroscopicity in cereal bars (Ali, Maqbool, Ramachandran & Alderson, 2010). Solutions of gum arabic are very low in viscosity, forming solutions with high viscosity at concentrations above 30% (p/p) (Goff & Guo, 2019). It is an almost odorless, tasteless, water-soluble gum, forming a limpid and nontoxic solution. Thus, it can be utilized in food bars, reducing their caloric value (Calame, Thomassen, Hull, Viebke & Siemensma, 2011).
Collagen is a substance in the family of proteins, found in animals, especially in the flesh and connective tissues of mammals (Mohammad, Suhimi, Aziz & Md Jahim, 2014).
Since it easily dissolves in water, partially hydrolyzed collagen is very useful in the food industry as it acts as an emulsifier, foaming agent and colloid stabilizer (Gómez-Guillén et al., 2011).
Few studies show the possibility of other non-sugar derivative binders. Tramujas, de Carli, do Prado, Lucchetta and Tonial (2017) showed that the use of collagen, guar gum and xanthan gum in salted cereal bars is an alternative to replace sugar as a binding agent. Srebernich et al. (2016) used acacia gum in cereal bars with the addition of inulin and sorbitol, obtaining the desirable texture and good sensory acceptance.
The food industry faces challenges to design healthier products that resemble the Development, v. 9, n. 11, e8269119958, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i11.9958 5 conventional concerning physical, physicochemical and sensory characteristics (Simoncello et al., 2020). Thus, the objective of this work was to manufacture salted cereal bars with different concentrations of the binding agents modified starch, hydrolyzed collagen and acacia gum to evaluate 1) the effect of different concentrations of binding agents in the cereal bar through physical, chemical, physicochemical analyzes and 2) consumer acceptance of the salted taste cereal bars with different binding agents.

Methodology
The salted food bars were developed and analyzed quantitatively according Pereira, Shitsuka, Parreira and Shitsuka (2018) in relation to the centesimal composition, caloric value, soluble and insoluble dietary fiber, minerals, antioxidant activity, pH, water activity, color and texture profile. The methodologies for each analysis are described below.

Preparation of cereal bars
Considering the difficulty of finding research on salted cereal bars, the formulations were developed according to pre-tests to stipulate the minimum necessary amounts of binding agents and basic ingredients to obtain a salted cereal bar with a texture similar to sweet cereal bars, however, with low caloric value. The food bars were manufactured by weighing the ingredients, which were: a) basic ingredients (salted granola, partially dehydrated tomato, seasonings and salt) and b) binding agents (modified starch or hydrolyzed collagen or acacia gum) at three different proportions (4.5%, 6.5% and 8.5%) for each agent, aiming to prepare binding solutions, amounting to nine solutions, that is, nine distinct food bars (Table 1).  In Table 1, it is important to observe the variation in the concentrations of binding agents used in the preparation of food bars.
The basic ingredients, previously weighted, were added to the binding solution, for the complete agglutination and homogenization of the dough, under heating, for 1.5 minutes. The dough obtained was cooled at room temperature for 25 minutes and then shaped in rectangular pieces of 10 cm x 3 cm x 15cm, approximately. The bars were placed in a forced ventilation oven for drying at 65°C for 20 hours. The moisture loss of the bars was taken into consideration during the drying period, obtaining the final product with around 25 grams of moisture. After that period, the food bars obtained were packed in transparent plastic polyvinyl chloride (PVC), as the primary package, in addition to aluminum foil (secondary package) and glass containers (tertiary package).
The analyses of pH was performed utilizing a Schott Handylab digital potentiometer, according to the AOAC (2005), water activity, with use of an Aqua Lab® apparatus, with determination of the dew point on encapsulated mirror (AOAC, 1997). Color was determined by a Minolta colorimeter, Chroma Meter CR-3000 model under the L*a*b* Cielab system, according to the methodology of Bible and Singha (1997).

Total antioxidant activity
The total antioxidant activity was determined through the DPPH method (Rufino et al., 2007), with adaptations, the results being expressed in Effective Concentration 50% (EC50).

Texture profile
Texture profile analysis (TPA) was conducted in a texturometer (Stable Micro Systems Model TA-XT2i; Goldaming, England) under the following conditions: pre-test velocity of 1.0 mm/s, test velocity of 1.0 mm/s, post-test velocity of 1.0 mm/s, compression distance of 20.0 mm and with an aluminum cylindrical probe of 6.0 mm diameter (Szczesniak, 1963). The studied parameters were hardness, fracturability and chewability.

Statistical analysis
The effect of treatment was evaluated by variance analysis, followed by Scott-Knott test, at 5% of significance to identify the differences in significant cases. The variance analyses and the means test were conducted on Sisvar 5.1 Build 72 software (Ferreira, 2011). Research, Society and Development, v. 9, n. 11, e8269119958, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i11.9958  obesity, like all secondary diseases derived from this condition. However, its intake has been much less than the recommended (King et al., 2012;Fernstrand, Bury, Garssen & Verster, 2017), which increases the importance for providing food products with higher levels of Research, Society and Development, v. 9, n. 11, e8269119958, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i11.9958 dietary fibers. The fiber content presented by the food bars G, H and I showed that the intake of 25g of this product contributes with 35.04%, 37.04% and 39.56% of the adequate daily fiber intake, respectively, for females between 19 and 50 years old.

Taking into consideration the classification of dietary fiber into soluble and insoluble
fiber, it is estimated that for a daily intake of 25g of total dietary fiber, 18.75g should be insoluble fiber and 6.25g soluble fiber. Thus, the same food bars G, H and I contributed with 33.50%, 32.37% and 33.60%, respectively, of the recommended daily intake of insoluble fiber, and with 39.68%, 50.88% and 57.44%, respectively, of the recommended daily intake of soluble fiber.
In studies conducted by Sampaio, Ferreira and Brazaca (2010) with food bars containing rice flakes, flaked oats, corn flakes, dehydrated apple, chocolate, corn syrup, and brown sugar, contents of 6.01% total fiber were found, 2.93% of which being soluble fiber and 3.08% insoluble fiber. These values are much lower than those found in this study, in which the high fiber content of the salted food bars standing out.
Considering a food bar containing 25g, a value usually used by companies producing this kind of food, the bar G (4.5% GA) presents 71.04 kcal, the bar H (6.5% GA) around 70.46 kcal and the bar I (8.5% GA), 67.53 kcal.
The finding regarding sample I may be explained since acacia gum is rich in minerals. Ali, Elkarim, Fageer and Nour (2012) showed that Na, K, Ca, Mg, Mn, Fe, Cu, Zn, Br, Rb, Sr and Zr were presented in 10 types of acacia gum. Lopez-Torrez, Nigen, Williams, Doco and Sanchez (2015) found that the mineral content, on dry basis, of A. Senegal is 33.0 and A. seyal 40.0 (mg/g).
The food bar I also presented the highest amount of sodium among all the bars developed. However, a food bar of 25g presents 137.5 mg of sodium, which represents 9.2% of the appropriate sodium content in the daily intake of males between 19 and 30 years, showing that this value, associated with a wholesome diet, proves feasible.

Total antioxidant activity, pH and water activity
The values for total antioxidant activity, pH and water activity of the salted food bars developed are presented in Table 4.  The water activity of bars A, B and C, which contain modified starch and F (8.5% of hydrolyzed collagen) and H (6.5% acaia gum) presented the highest water activity, with no significance difference (p>0,05). Aigster, Duncan, Conforti and Barbeau (2011) explained that the increase in water activity in cereal bars containing starch in the formulation is due to the retrogradation of starch molecules resulting in water release.
Water activity measurements help to predict food mechanical properties, stability and shelf life (Rawat and Darappa, 2015).The values of water activity found in the present study (under 0.4) suggests safe food in relation to the growth of microorganisms, considering the ideal Aw for the growth of most microorganisms is above 0.9. Therefore, this is an important parameter which indicates the conditions for the growth of microorganism and the safety of the food for consumer health (Damasceno et al., 2016). Table 5 presents the results of the analysis of the color of the food bars. According to the analyses carried out, the manufactured food bars showed no significant difference (p> 0.05) among them in relation to the color parameters L*, a* and b* analyzed. According to the Table 5, in general, it is important that the salted food bars developed in the current study presented low L* values, which means that they are darker products, closer to black than white. The drying process of the salted bars possibly resulted in products with low luminosity indices, whereas sweet bars developed in several studies, with high L* values, were not subject to the drying process after being manufactured. Studies showed that the value of L* is also affected by level of sweetener in the cereal bar (Sharma & Mridula, 2015), or by ingredients such as pear and wheat bran that may decrease the values of L* (Bchir, Jean-François, Rabetafika & Blecker, 2017).

Color
Regarding the parameter a* (green to red), the salted food bars and the bars developed in other studies showed close values and parameter b* (blue to yellow) presented lower values. Waterhouse et al. (2010) found values close to 60.0 for L*, near 5.0 for a* and near 20 for b* in their developed food bars.

Texture profile analysis
The  (Table 6). Texture is an important parameter to be studied since it may influence sensory analyses. Pallavi et al. (2015) showed that cereal bars with low sugar also presented lower overall quality score because of harder texture and reduced chewiness. However, the findings are in accordance with Damasceno et al. (2016), who found that hardness of cereal bars with pineapple peel flour range from 99.60 -157.95N, and the higher hardness values were related for the cereal bar with higher amount of flour.
Concerning the parameter chewability and according to the results showed in Table 6, the food bars containing acacia gum presented the highest chewability values implying that these bars demand an increased energy potential to be chewed until the point of being swallowed. This result is due to the high amount of fiber presented by the samples G, H and I. Marques et al. (2015) showed that the increase in the amount of total fiber causes an increase in the firmness of cereal bars. This result is related to an increase in the cheweness of the product. Rawat and Darappa (2015) showed that cereal bars with high fiber values have higher chewiness values. On the other hand, the same study showed that the addition of protein decreases the chewiness value, as can be seen in samples D, E and F.

Conclusions
The three binding agents tested in this study (modified starch, hydrolyzed collagen and acacia gum) presented technical viability of agglutination of the ingredients. Related to the texture properties, cereal bars produced with acacia gum presented higher chewability values.
Also, food bars containing acacia gum presented low caloric value, high content of dietary fiber and minerals such as magnesium, manganese and greater antioxidant power regardless of the concentrations of this binder, increasing the possibility of their use for the same technological purpose in several types of food products. Gum acacia, as a binding agent, stood out in some parameters compared to the other two binding agents of this study.
Further studies should be done to improve the texture of these bars, as well as the addition of flavorings to evaluate sensory acceptance and purchase intent of the product.