Characterization of Aiphanes aculeata fruit pulp and application in ice cream formulations

The characteristic color of the palm fruits Aiphanes aculeata, also known as Cariota-de-Espinho, suggests the presence of pigments such as carotenoids and anthocyanins, in addition these fruits present other compounds with health benefits such as minerals, vitamins and phenolics. However, there are no studies on the application of these fruits in food formulations since this palm tree is used only for urban landscaping. The present study aimed to characterize the Aiphanes aculeata pulp for proximate composition, physicochemical parameters, mineral contents, bioactive compounds, and antioxidant activity. Three ice cream formulations with the addition of different pulp concentrations were also produced, aimed to contribute to the technological and nutritional use of Aiphanes aculeata fruits. The choice of ice cream as the main investigation occurs due to the importance of functional ice creams to the balance of the physiological functions of the human organism that occurs through the ingestion of active and nutritional ingredients. Ice creams were characterized for overrun, melting behavior, color, and texture profile. The pulp presented representative minerals levels such as iron (49.82 ± 43.85 mg/100g) and zinc (96.07 ± 81.65 mg/100g). The total carotenoids level was significant, corresponding to 92.64 ± 0.83 μg/100g, with an emphasis on the betacarotene levels (56.94 ± 2.11 μg/100g). The different pulp concentrations used in the formulations influenced the characteristics of the ice cream, as it interacted positively with the ingredients until the concentration of 30% pulp. Therefore, the Aiphanes aculeata fruits showed potential for application in the food industry, in the manufacture of ice cream with high nutritional value.

It is a palm tree native to Latin America, found mainly in Brazil (Amazonas and Acre), Venezuela, and Bolivia, and has a characteristic feature of a stem covered with pointed spines and red fruits when ripe (Smith, 2015). The physicochemical and nutritional characteristics of the A. aculeata pulp are practically unexplored since the palm is predominantly used in urban landscaping, due to its ornamental importance (Moraes, Machado & Araújo, 2015).
The fruits of the Aiphanes aculeata palm have a characteristic color due to their rich composition in carotenoids and anthocyanins, especially zeaxanthin, in addition to other nutrients with health benefits such as antinociceptive and antiinflammatory effect (Lakey-Beitia, Kumar, Murillo, & Patricia, 2017). In general, palm trees are known to be rich in oils, terpenoids, and phenolic compounds (Agostini-Costa, 2018). These compounds have antioxidant potential, slowing aging and defending the body's tissues against oxidative stress and pathologies associated with inflammatory processes and cancer (Santos, Alves & Roca, 2015), therefore with a great potential to be used as substitutes for synthetic agents in the pharmaceutical and nutraceutical industries (Maqsood et al., 2019).
In recent years, there has been an increase in studies about new functional food products using native Brazilian fruits (Schiassi et al., 2017). In this context, functional ice cream stands out, which is defined as a nutritious frozen dessert that provides high energy to consumers and is considered a complement to the diet with positive effects on human health (Öztürk, Demirci, & Akın, 2018). More nutritious and healthy functional ice cream can be produced by the addition of fruits and constituents rich in proteins, fibers, bioactive compounds, probiotics, and prebiotics (Öztürk et al., 2018). Therefore, the general objective of this study was to characterize the pulp of the native fruit Aiphanes aculeata (Family Arecaceae), In addition, the main objective is the development of innovative and functional products based on native fruit from Brazilian agroforestry systems, which will have its added value increased and an opportunity for sustainable economic use of forest resources. For this, a functional ice cream was investigated and developed in order to understand its potential and nutritional and antioxidant value for the maintenance of human health.

Obtaining the raw materials
The fruit pulp of Aiphanes aculeata was collected at the State University of Maringa, located in Maringa/PR-Brazil, and stored for a maximum of 4 wk at 6 °C. For the manufacture of ice cream, the fruits were stored frozen until use and the other ingredients including milk yeast (BioRich TM ), cream (fat contain, Frimesa TM ), stabilizer (Super liga neutra -Duas Rodas TM ), emulsifier (Emustab Selecta -Duas Rodas TM ), and commercial sugar were purchased in the local market of Maringa/PR. The milk was purchased at the Iguatemi Experimental Farm (FEI). All analyses were performed in triplicate

Obtaining the fruit pulp
The fruit of Aiphanes aculeata palm was washed in running water to remove visible dirt or particles, and dried using a paper towel. The pulp was removed from the fruit until obtaining a homogeneous paste by homogenizer (Britânia, BMX630PI, Joinville, Santa Catarina, Brazil).

Composition
The moisture content, total lipids, crude fiber (acid and alkaline digestion), ash, and acidity were determined according to the methods described in the analytical standards of Instituto Adolfo Lutz (2008). The protein content was determined by the total nitrogen (%), according to the Kjeldahl method, as described by the Association of Official Analytical Chemists (AOAC) (1990). Carbohydrates were calculated by difference, by subtracting the values obtained for moisture, protein, lipids, ash, crude fiber, and protein from 100.
The pH values were determined by the potentiometric method. The soluble solids content was determined by reading in an Abbé refractometer at 20 °C and expressed in °Bx. The reducing sugars (expressed as % glucose) were determined by the volumetric method using Fehling solutions (Instituto Adolfo Lutz, 2008).

Color measurements
The color of the pulp was measured using a portable colorimeter (Minolta, CR10). The results were expressed as L*, a*, and b* values, in which L* (luminosity or brightness) varies from black (0) to white (100), a* varies from green (-60) to red (+60), and b* varies from blue to yellow, i.e., from -60 to +60, respectively. The color coordinates a* and b* were used to calculate the Hue angle (°h = tang-1 (b*/a*)), which indicates the fruit tonality (Bible & Singha, 1993).

Mineral content
The minerals calcium, iron, magnesium, and zinc was found by atomic absorption spectrophotometer (Perkin-Elmer, 2380, Waltham, Massachusetts, USA), using a standard curve for each mineral, as proposed by Salinas & Garcia (1985).

Carotenoids content
The extraction of carotenoids was performed as reported by Pacheco (2009). The Aiphanes aculeata pulp extracts were kept refrigerated for 24 h. Then, the samples were weighed using an analytical balance (Bioprecisa, FA2104N, Curitiba, Paraná, Brazil). Then, 3 g of celite (454) was added and the carotenoids were extracted with HPLC grade acetone. The Research, Society and Development, v. 10, n. 5, e45710515184, 2021 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v10i5.15184 4 resulting extract was transferred to a 500 mL separating funnel containing about 40 mL of HPLC grade petroleum ether. The total carotenoids were quantified in a UV-visible spectrophotometer (Thermo Scientific, Evolution 60, Waltham, Massachusetts, USA), in the visible spectrum range, with absorbance readings at 450 nm, using HPLC grade petroleum ether as a blank.

Obtaining the anthocyanin extracts from the Aiphanes Aculeata pulp
The anthocyanins extraction was performed according to the methodology by Teixeira, Stringheta & De Oliveira (2008) with modifications. A pulp:ethanolic solution (70%) ratio of 1:2 was used for the extraction. The mixture was subjected to stirring on a magnetic stirrer for 40 min and protected from light. After extraction, the mixture was filtered and centrifuged at 4000 rpm for 10 min. The removal of chlorophyll from the extract was performed by extraction using 150 mL aliquots of ethyl ether: petroleum ether 1:1, for 3 times, using a separating funnel. The extract was concentrated to 30% of the initial volume in a rotary evaporator at 45 °C and protected from light, frozen in liquid nitrogen, and freeze-dried at -50 °C for 24 h.
The freeze-dried material was stored in a freezer at -20 °C.

Total anthocyanins
The content of total anthocyanins was determined using the differential pH method as described by Lee, Durst & Wrolstad (2005). For that, two buffer systems were used, consisting of 0.025 M potassium chloride at pH 1.0 and 0.4 M sodium acetate at pH 4.5. The samples were previously filtered on Whatman 1ø filter paper, and absorbance readings were performed in spectrophotometer (Thermo scientific, Genesys 10S UV-Vis, Waltham, Massachusetts, USA) at 520 nm, using distilled water as a blank.

Phenolic contents and the antioxidant capacity of the extract
The quantification of total phenolic content (TPC) of both pulp and ice creams were determined using the Folin-Ciocalteu colorimetric method described by Singleton & Rossi (1965) with some modifications by Ribeiro et al. (2019).
Briefly, the extract (30 μL) was mixed with 2370 μL of water, and then 150 μL of the Folin-Ciocalteu reagent was added, and the mixture incubated in the dark for 3 min at 25 °C. Then, 450 μL of 20% Na₂CO₃ was added and incubated for 2 h. The absorbances were done with a spectrophotometer (Thermo scientific, Genesys 10S UV-Vis, Waltham, Massachusetts, USA) at 765 nm.

. Manufacture of ice cream
The following ingredients were used to produce the ice creams: fruit pulp (15, 30, and 60%), milk (85, 60, and 40%), sugar (18%), cream (5%), stabilizer (1.5%) and emulsifier (1.5%). A formulation without the addition of fruit pulp was used as a control. First, the pulp was mixed with milk, then homogenization with the other ingredients, the ice cream was processed in discontinuous artisanal equipment at -18 °C for approximately 20 min. After manufacture, the ice creams were stored protected from light at -18 °C (Campos et al., 2016).

Determination of overrun
The air incorporation in the ice cream was determined by measuring the volume of the initial mixture (Vi) and the volume of the final product (Vf). The overrun was calculated by Equation 1 (Segall & Goff, 2002):

Texture profile
The texture profile of the samples was determined four weeks after the ice cream manufacture, in triplicate, using a texture analyzer (Syable Micro System TA-XT2i) and a P/36R probe, and the results were presented in kgf compression strength.

Melting behavior
For the melting test, 100 g of ice cream was kept in the freezer for 60 min. Then, the sample was placed on a metallic sieve, with sieve opening size of 0.5 cm at room temperature, and the drained ice cream was weighed every 10 min (Granger et al., 2005). This procedure was performed for 4 consecutive weeks from the day of manufacture, in triplicate.

Statistical analysis
Data were analyzed by analysis of variance (ANOVA) and Tukey's test to compare means at the level of 5% of significance. The Statistica 7.0 software (StatSoft, Tulsa, OK, USA) was used for this analysis.

Composition and physicochemical parameters
The results of the composition and physicochemical parameters of the Aiphanes aculeata pulp are shown in Table 1. It is important to note in Table 1 that the calcium and magnesium levels were 37.92 mg/100g and 60.67 mg/100g, respectively, which was lower than that obtained by Lescano et al. (2015) in macauba pulp (130 mg/100g and 123 mg/100g, respectively). On the other hand, the iron and zinc levels of the Aiphanes aculeata pulp were 49.82 ± 43.85 mg/100g and 96.07 ± 81.65 mg/100g, respectively, which was higher than the values found by Lescano et al. (2015) in macauba pulp, who obtained an iron level of 4.13 ± 0.06 mg/100g, and zinc levels below the quantification limit, which is 3.33 µg/g.
As reported by Silva et al. (2008), there is a relationship between ºBx and the sugar and organic acids contents that connect to consumers preference for sweet fruits. The ºBx value found for the Aiphanes aculeata pulp (7.10 ± 0.20) was higher than that observed by Schiassi et al. (2017) in buriti pulp (4.33 ºBx). The pH value of Aiphanes aculeata pulp was 4.84 ± 0.08, which was higher than that reported by Sandri et al. (2017) in buriti pulp (3.78 ± 0.04) and lower than that reported by Lescano et al. (2015) in macauba pulp (6.00 ± 0.00). The low pH values may be due to the content of dissociable acids present in the fruit (Sganzerla, 2010), such as ascorbic, malic, tartaric, and citric acids.
The reducing sugars, in glucose, in the fruit pulp was 0.71 ± 0.01%, which was significantly lower than the content found by Sandri et al. (2017) in buriti pulp (4.50 ± 0.14 %).
The determination of acidity in fresh products is important to study the product conservation since this information can be related to microbial growth and fruit storage conditions (Instituto Adolfo Lutz, 2008). The titratable acidity, expressed as citric acid, in Aiphanes aculeata pulp was 0.43±0.04%, which was close to that found for macauba pulp with a value of 0.27 ± 0.03% (Lescano et al., 2015) and significantly lower than that observed for buriti pulp, with 8.82 ± 0.16% (Sandri et al., 2017). The water activity of the fruit pulp was 0.96, which was close to that of buriti pulp (0.98 ± 0.02) reported by Sandri et al. (2017).
Regarding the color measurements, the pulp showed positive a* and b* values, corresponding to red and yellow color, respectively. These results are in accordance with the findings of Schwartz et al. (2010), who studied Butia capitata, also belonging to the Arecaceae family.

Overrun
In the determination of overrun, the incorporation of air ranged from 40 to 66%, as shown in Table 3, which is in agreement with the results of Öztürk, Demirci, e Akın (2018) for ice cream made with Myrtus communis pulp, which exhibited overrun ranging from 40.95 to 42.98%. The formulation with the addition of 30% Aiphanes aculeata pulp showed the highest overrun, probably due to its composition, giving the product a greater creaminess, and consequently higher yield. The incorporation of air into the ice cream depends on the total solids content, and in general, there is an increase in overrun with the increase in total solids, improving the ice cream characteristics such as the texture. However, Goff and Hartel (2013) reported that total solids content above 42% can lead to very dense products and, consequently, with lower incorporation of air. This event may have occurred in formulation 3, which contained a higher pulp concentration, and higher total solids and fiber contents, resulting in a product with lower incorporation of air. The results corroborate the findings of the characterization of Aiphanes aculeata fruits, which presented 1.76% crude fiber, contributing to higher fiber content in the formulations made with the higher pulp concentration, thus requiring more force during beating to increase the incorporation of air in the ice cream. Research, Society andDevelopment, v. 10, n. 5, e45710515184, 2021 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v10i5.15184 8 As can be seen in Table 3, the b* values increased with increasing the pulp concentration. This result may be due to the addition of pulp and other components to the ice cream mixture to increase the functionality and improve the sensory properties, leading to a reduction of L* values and an increase in b* values of ice cream (Öztürk et al., 2018). Table 3 shows the results of the texture profile analysis of the ice cream formulations. Dervisoglu & Yazici (2006) studied the effect of the addition of citrus fibers to ice cream and reported that the fiber reduced overrun, as it increased the product's viscosity. This behavior was also observed in F3 (60%), which contained the highest pulp concentration and presented a lower hardness and higher adhesiveness. The formulation 2 showed greater overrun and hardness when compared to other formulations, due to the greater volume of the frozen mixture. In addition, F2 showed greater gumminess and chewability, requiring a greater strength to break down and chew the ice cream, respectively (Silva et al., 2013). No significant differences were observed for the adhesiveness of the samples, that is, they presented similar efforts to break the attraction forces between the product and the contact surface (Goff & Hartel, 2013).

Melting behavior
The melting test was performed for 4 weeks, as shown in Figure 1. It is important to note in Figure 1 that the formulation F3 presented a more discrepant behavior, starting the melting process after the other samples, probably due to lower incorporation of air and a higher pulp concentration, conferring a great firmness to the product. As reported by Correia et al. (2008), high total solids levels and low overrun may be associated with slower melting.
An ideal melting behavior is characterized by a sequence of events, with the product becoming a smooth and homogeneous fluid (Goff & Hartel, 2013). Therefore, the formulation F1 (15%) showed a behavior closer to the ideal, with more homogeneous melting and a curve closer to the control. The ice cream made with the highest pulp concentration (60%) showed a lower overrun and slower melting, in addition to a more fibrous and dense aspect when compared to the others. This result may be due to the high molecular weight, leading to a firmer agglomerate and higher product viscosity (Silva Junior & Lannes, 2011). In addition, other factors can affect the process including the rate of air incorporation (overrun), lipid interactions, and fat crystallization (Sofjan & Hartel, 2004). The addition of 15 and 30% pulp to the ice cream formulations provided a melting behavior close to the control, with an expected melting resistance and good creaminess. It is worth noting that ice creams with the addition of Aiphanes aculeata pulp had higher total phenolic compounds (Table 3) with functional properties when compared to traditional ice creams.

Conclusion
The Aiphanes aculeata fruit pulp exhibited behavior similar to the fruits from the same species or family, which have already been used in the food industry. For the manufacture of functional ice cream, the pulp showed adequate interaction with the ingredients up to a concentration of 30%, with high levels of total phenolic compounds and good performance of the characteristics studied, with positive effects on overrun, melting behavior, and texture profile. Therefore, the fruit can be an alternative source for the manufacture of food products with high nutritional value, some of which have the functional potential to benefit human health. A diet rich in phenolic compounds is linked to a decreased risk of multiple diseases, so consumers increasingly want to consume natural ice cream with enhanced bioactivity, that is, with more active ingredients such as phenolics and antioxidant activity. For future work, investigate toxicity and perform sensory analysis and thus apply the pulp in the development of other foods.