Physicochemical and Sensory Properties of Sugar Cane Candies with Roasted Peanut and Extruded Rice Bran

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Emerging impurities were removed with a ladle during the concentration of SJ, and when it reached 80°C, it was vigorously stirred for incorporation of air and texture development. The heating continued with constant stirring until reaching 120°C, when it was transferred to another vessel where RP and ERB were added, mixed and then distributed into molds of 25 g. After cooled, sugar cane candy was unmolded and immediately packed in low density polyethylene film. The sugar cane candies were stored in cool boxes at room temperature, it were kept in these conditions until analysis, approximately 60 days.

2.3. Physicochemical Characteristics

Particles size (mm) of ERB and RP were assessed in vibrating equipment (Produtest, T, São Paulo, Brazil), according to the methodology described by Dias and Leonel ^[11]. Color parameters (L*, a* and b*) of sugar cane candies were determined with a colorimeter (ColorQuest II, HunterLab, Reston, Canada), and hardness (N) was determined with texturometer (TA, XT2, Halesmere, England), with test speed of 2 mm s^-1, distance of 18 mm, force of 0.98 N and probe type knife HDP/BSK. Contents of ash, protein, lipids, total dietary fiber, soluble dietary fiber, and insoluble dietary fiber (g 100 g^-1) of the raw materials and sugar cane candies were determined according to the methods recommended by AOAC ^[12]. Carbohydrate content (g 100 g^-1) of the sugar cane candies was obtained by difference and the total energy value calculated with the Atwater conversion factors ^[13].

The microbiological analyses and acceptance sensory were carried out in the formulation of sugar cane candy indicated by the desirability test.

2.4. Microbiological Analysis

Samples were collected and analyzed according to National Health Surveillance Agency (ANVISA) Resolution RDC No. 12 of January 2, 2001 ^[14].

Dilutions from 10^-1 to 10^-6 and the inoculations were carried out according to methodology proposed by Vanderzant and Splittstoesser ^[15], in order to perform the counting of molds and yeasts, determination of the most probable number per gram of total and thermotolerant coliforms, counting of Staphylococcus aureus and determination of the Bacillus cereus, which were investigated according to techniques described by the Food and Drug Administration.

2.5. Acceptance Sensory

The appearance, texture, flavor and odor were evaluated in laboratory scale using a nine point hedonic scale 9 = like extremely, 5 = not liked nor disliked and 1 = disliked extremely) according to design of randomized blocks, and positive, maybe or negative purchase intent ^[16]. Acceptance sensory was performed in individual cabins with 50 homogeneous testers (16 men and 34 women), aged between 18 and 37, with high educational level and previous experience with sensory analysis (94%). According Dutcosky ^[17] the homogeneity of the sampling taster is much more important than the number of tasters. For each segment of tasters, from 45 to 50 tasters are sufficient (Dutcosky, 2013; Mirim, 2013) ^{[17, 18]}.

The sample, cut into 3 cm × 3 cm pieces, was served on plastic plates and in a sequential monadic manner with a completely randomized design. The acceptance test was conducted after approval by the Ethics Committee (number 113/11).

2.6. Analyses of Results

The fitted polynomial models were subjected to analysis of variance, and with the help of the function “Response Desirability Profiling” (MicroStat, Statistica 7.0, Tulsa, USA), of the significant fitted models, the most desirable formulation was determined, considering as such the one with the highest values of luminosity, hardness, ash, protein, lipids and total dietary fiber (more balanced in relation to the nutritional value). All data were evaluated using the Statistica 7.0 software, including the analysis of variance (ANOVA) and average comparison using Tukey test (p≤0.05). All experiments were carried out in triplicate.

3. Results and Discussion

3.1. Physical and Chemical Properties

ERB had 80.00 g 100 g^-1of the particles retained in the 2.83 mm sieve, 8.90 g 100 g^-1on the bottom and 11.10 g 100 g^-1 distributed among the sieves 2.19, 1.68, 1.19 and 0.54 mm, while for the RP, 32.90 g 100 g^-1of particles were retained on the 2.83 mm sieve, 30.10 g 100 g^-1on the 2.19 mm sieve, 13.00 g 100 g^-1 on the 0.54 mm sieve and 24.00 g 100 g^-1on the other sieves, so both presented coarse particle size, but ERB was the more irregular.

Contents of ash, protein, lipids, carbohydrates, dietary soluble, insoluble and total fiber, and total energy were lower, of SJ were lower than in the other ingredients (Table 2).

Table 2. Proximate composition (dry matter basis) and total energy value of extruded rice bran (ERB), roasted peanuts (RP) and sugarcane juice (SJ)

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The content of ash, soluble dietary fiber and carbohydrate of ERB were respectively 3.2, 3 and 2.5 times higher than in RP. On the other hand, the content of proteins, lipids and total energy value of RP were respectively 126%, 170% and 40% higher than those of ERB. The instrumental color parameters obtained for the standard sugar cane candy (SJ only as raw material) and for those made with SJ, RP and ERB (experimental), as well as hardness, proximate composition, total energy value are listed in Table 3. Models for L*, hardness, ash, protein, lipids and total dietary fiber were significant, explaining 96 to 99% of the responses and the lack of fit was not significant (Table 4).

Models for chroma a* and b*, soluble and insoluble dietary fiber were not significant and are not shown. Chroma a* and b*ranged from 5.01 to 7.64 and 12.92 to 20.4, respectively, and the candies had tendency to an orange color (Table 3).

The highest values of L* were obtained between points A, B and the experimental point 2 (Figure 1A), thus, lighter experimental mixtures were those with higher content of ERB, between 18.3 and 20 g 100 g^-1 and lower content of RP (about 5.00 - 6.70 g 100 g^-1) and of SJ (between 75.00 and 75.50 g 100 g^-1).

The heating of sucrose and reducing sugars promotes the reactions involved in caramelization and darkening ^[19], so in the sugar cane candy the SJ (rich in sugars) was responsible for those reactions and for the typical aroma and flavor of sugar cane candy. However, the inclusion of solids components (RB and RP) lightens the color of the candy in comparison with the control candy and the formulations with higher concentrations of SJ (SCC1, SCC3 and central point). In Figure 1B, the area between points A, B and 2 contained the higher values of hardness (above 50 N), higher than those found in the standard sugar cane candy (Table 3). Therefore, the hardest experimental sugar cane candy was the one formulated with higher amounts of ERB (between 18.60 and 20.00 g 100 g^-1) and lower of RP (between 5.00 and 5.50 g 100 g^-1) and of SJ (between 75.00 and 76.40 g 100 g^-1).

Table 3. Physicochemical characteristics of the standard sugar cane candy (SCS pure) and the experimental made with different levels of extruded rice bran, roasted peanuts and sugarcane juice

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Table 4. Fitted polynomial models, with significance level (p), lack of fit (LF) and coefficient of determination (R²) for L*, hardness, ash, protein, lipids and total dietary fibre as a function of the coded levels of extruded rice bran (x₁), roasted peanuts (x₂) and sugarcane juice (x₃)

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Figure 1. Lightness (A), hardness (B) and ash content (C) of the experimental sugar cane candy according to the levels of sugarcane juice, extruded rice bran and roasted peanuts

The greater the amount of RP, the easier the product was broken during the compression test, probably because the RP consisted of large particles, which negatively interfered in the structural arrangement and in the cohesiveness. RP particle allowed the formation of voids within the product, where the breaks were observed during the analysis. The amount of ERB interfered in the maximum strength of the compression required during testing, since the higher its concentration in the mixture the greater the strength necessary to break it. The ERB, especially the most crumbled fraction, probably helped to form a more cohesive internal structure, which hampered its break during compression.

A trend was shown about the ash content, which the higher the ash content the greater the amount of ERB and the lower the SJ. The highest ash content (3.20 g 100 g^-1) was obtained in the delimited area between points A, B and 2 (Figure 1C), in sugar cane candy formulated with 18.30 to 20.00 g 100 g^-1 of ERB, 5.00 to 6.00 g 100 g^-1 of RP, and 75.00 to 76.70 g 100 g^-1 of SJ. The lowest ash content (2.6%), represented in the area formed by points C and D and the experimental points 1 and 3, was found in the sugar cane candy with formulations with 10.00 to 15.30 g 100 g^-1of ERB, 5.00 to 10.00 g 100 g^-1of RP, and 79.60 to 85.00 g 100 g^-1 of SJ.

Comparing the ash content in the experimental sugar cane candy found in this study (Table 2) with the content found in other studies related to the composition of pure sugar cane candy, which was between 1.70 and 1.54 g 100 g^-1 [3 and 9 respectively], there was an increase of ashes in the formulated candies, ranging between 34.92 and 63.37% which reiterates the importance of including ERB and RP.

The maximum amount of ash permitted by the Brazilian legislation for sugar cane candy is 6.00 g 100 g^-1^[2]. The ash content indicates the amount of minerals present in the food, which are essential to the functioning of the organism, but high concentrations of ash can also indicate the presence of impurities, from fraud or contamination during the manufacturing process.

In relation to the protein content, the highest value was found in the sample SCC4 with the highest amounts of RP and ERB and the lowest of SJ (Figure 2A), area delimited by points A, B and 4, in formulations with 15.00 to 17 g 100 g^-1of ERB, 9.70 to 10.00 g 100 g^-1of RP, and 75.00 to 79.00 g 100 g^-1of SJ. RP was the component with the highest protein content. Freitas and Naves ^[20], in studies on the chemical composition of nuts and edible grains, stated that in general, edible grains, such as peanuts, meet much of the essential amino acids required for children and adults, with the exception of lysine, methionine and cysteine, compared to the most recent standards of the World Health Organization ^[21]. The sugar cane candy enriched with ERB and RP would be a major contributor to meet those needs, especially if included in school meals, since the RP could meet part of the essential amino acids required for school children.

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Figure 2. Protein, lipid and total dietary fiber of the experimental sugar cane candy according to the contents of sugarcane juice, extruded rice bran and roasted peanuts

The lowest protein content (4.5 g 100 g^-1), which is represented in the area of the graph inside the area delimited by points C, D and 1 (Figure 2A), in sugar cane candy with formulations from 10.00 to 10.50 g 100 g^-1of ERB, 5.00 to 5.30 g 100 g^-1 of RP, and 84.50 to 85.00 g 100 g^-1 of SJ.As the standard sugar cane candy exhibits low content of protein, the values of this nutrient found in sugar cane candy formulated are from the ERB and the RP and has a better nutritional balance than the standard.

The highest level of lipids were observed in the higher concentrations of RP and ERB and lower of SJ, sample SCC4. In the area delimited by points A, B and4 (Figure 2B), were observed the highest contents of lipids (7.67 g 100 g^-¹), corresponding to formulations with 15.00 to 17.00 g 100 g^-1 of ERB, 9.30 to 11.00 g 100 g^-1 of RP, 75.00 to 79.00 g 100 g^-1 SJ. The lowest content of lipids were verified in the area delimited by points C, D and 1, with 10 to 10.50 g 100 g^-1, 5.00 to 5.20 g 100 g^-1 of RP, and 84.50 to 85 g 100 g^-1 of SJ. The amount of lipids in formulated sugar cane candy was from RP, which contains high amounts of lipids (Table 2), while the standard sugar cane candy did not contain lipid.

Studies conducted by Fernandes ^[22] demonstrated that high content of mono and polyunsaturated fatty acids in peanuts resulted in an elevated relationship between omega 6 and omega 3. Lipids play an important role in the quality of food, since they contribute with attributes such as texture, flavor, nutrition and caloric density. The use of lipids has had special emphasis on research and development of food ^[19]. Lipid is among the main sources of energy used by man and provide more calories than carbohydrates and proteins ^[23]. The presence of lipids in the candy is important because it contributes in the balance of calories provided by the sucrose of the sugar cane.

The highest amount of total dietary fiber (2.20 g 100 g^-1) was found in the area delimited by points A, B and 2 (Figure 2C), with 17.70 to 20.00 g 100 g^-1 of ERB, 5.00 to 7.30 g 100 g^-1of RP, and 75.00 to 76.2 g 100 g^-1 SJ, because higher amounts of ERB, found in these formulations, that has the highest content of dietary fiber (Table 2). In the area between the points C, D and 1, the lowest contents of total dietary fiber were found (less than 1.4 g 100 g^-1) in formulations with 10 to 10.9 g 100 g^-1 of ERB, 5 to 6.6 g 100 g^-1 of RP, and 84.1 to 85 g 100 g^-1 of SJ. As the standard sugar cane candy has insignificant amounts of total dietary fiber, that amount is from the combination with ERB and RP (12.69 and 11.27 g 100 g^-1).

Solid foods, which are considered sources of dietary fiber, have at least 3 g fibers 100 g^-1 of solids. Among the formulations of sugar cane candy, the SCC4 had the highest fiber content (2.30 g 100 g^-1), 76.7% of the value considered important by the legislation and although it did not reach the value of 3 g 100 g^-1, there was a significant increase of up to 2.3 times in this constituent in compared with standard sugar cane candy. This increase can supply 2.28% of the daily requirement of a child that consume 25 g sugar cane candy formulated per day ^[13].

After the analyses of physicochemical characteristics of sugar cane candy, the desirability test was applied, in which the desirable sample was the one with maximum values of hardness and L*, since the most striking characteristic of sugar cane candy is its high hardness and lighter color. The high values found in the chemical characteristic of sugar cane candy (protein, lipids, total dietary fiber) make it a more nutritious food.

To determine the most desired formulation, scores were assigned to each parameter, 0 (zero) for the least desirable and 1 (one) for the most desirable. The result of the desirability test for obtaining sugar cane candy formulated, with high values of hardness, lightness, ash, protein, lipids and total dietary fiber, indicated as parameters coded as pseudocomponents, the amount of ERB, RP and SJ in 1, 0, 0 (SCC2 treatment), respectively, corresponding to 20.00 g 100 g^-1ERB, 5.00 g 100 g^-1RP and 75.00 g 100 g^-1SJ. This treatment is among those with the lowest amount of SJ, greater amount of ERB and lesser amount of RP, the latter two being responsible for the increase of most nutrients presented in formulated sugar cane candy.

3.2. Microbiological Parameters

The formulation of sugar cane candy indicated by the desirability test presented low count of total coliforms, thermotolerant coliforms, molds and yeasts, Staphylococcus aureus, Bacillus ceereus (10² NMPg^-1, < 10 NMPg^-1 , <100 CFU g^-1 e < 100 CFU g^-1, respectively) and absence of Salmonella spp (Table 5).

Table 5. Microbiological parameters of the sugar cane candy formulation indicated by the desirability test

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