Physical-chemical and biochemical characterization of Buchenavia tomentosa Eichler fruits

The savannah is the second largest Brazilian ecosystem and stands out for its great biodiversity, besides being an important agricultural frontier of the world. However, the process of agricultural development has undermined the ecosystem sustainability and contributed to the extinction of many species of animals and plants, including native fruit trees, wildlife base of support and source of food for local populations. On general, the fruits of the Brazilian savannah arouse an increasing scientific interest, due to their nutritional and functional properties, combined with the potential to add value and conserve the biodiversity of this biome (Siqueira et al., 2017).


Introduction
The savannah is the second largest Brazilian ecosystem and stands out for its great biodiversity, besides being an important agricultural frontier of the world.However, the process of agricultural development has undermined the ecosystem sustainability and contributed to the extinction of many species of animals and plants, including native fruit trees, wildlife base of support and source of food for local populations.On general, the fruits of the Brazilian savannah arouse an increasing scientific interest, due to their nutritional and functional properties, combined with the potential to add value and conserve the biodiversity of this biome (Siqueira et al., 2017).
The fruits of the savannah stand out because they have attractive organoleptic characteristics, present "sui generis" flavors and high levels of sugars, proteins, vitamins and minerals.They are consumed "in natura" or in the form of juices, liqueurs, ice creams, jellies among others.These characteristics make them interesting for biotechnological, food, pharmaceutical and medical applications (Caramori et al., 2004;Cardoso et al., 2011).
The Combretaceae family is in the Myrtales class, which consists of 20 genus and approximately 600 species of trees or shrubs.The most studied genus of this family areI: Combretum, Terminalia and Quisqualis.On Brazil, five native genus Buchenavia, Combretum, Conocarpus, Terminalia and Thiloa occur as well as two exotic ones, Bucida and Quisqualis (Souza & Lorenzi, 2008).The species Buchenavia tomentosa Eichler is a native tree from the Cerradão (forest formation of the savannah biome) and semi-deciduous forest, with an average height of 5 to 12 m and trunk diameter of 30 to 50 cm (Lorenzi, 2008).This species is popularly known as mirindiba, embiridiba, tarumarana or tonimbuca (Costa et al., 2011).The husk of its stem is used in popular medicine in the form of tea in the treatment of cough, such as antihyperlipidemic and anorexigenic (Silva et al., 2010).On the North Araguaia microregion (Mato Grosso, Brazil) the bark, flowers and fruits are used by the riverine community in the treatment of the high cholesterol, diabetes, high blood pressure (Ribeiro et al., 2017).
virulence factors, such as ability to form biofilms and adhesion in oral epithelial cells (Teodoro et al., 2015;Teodoro et al., 2018).The chemical characterization showed the presence of phenols compounds, such as the ellagic and gallic acids that demonstrated Candida albicans antibiofilm activity (Brighenti et al., 2017).The bark methanolic extracts also present phenolic compounds, resulting in high antioxidant activities (Teixeira et al., 2017).
Ots fruiting occurs in the months of June, July, August and September.Ots fruits have pulpy flesh which is sweet when ripe, containing a single seed (Lorenzi, 2008).They are consumed fresh as juice or sweet, and in popular medicine they are used in the treatment of cough (Ferreira et al., 2016).On some regions they are considered toxic, since their consumption could cause digestive alterations and abortions in goats, sheep and cattle (Mello et al., 2010).
However, such effects have not been observed in studies with rats.Nunes et al. (2010) observed mild toxicity, such as increased feed and weight gain in broodings of rats fed a 10% diet of B. tomentosa fruits.On another study, the fruits aqueous extract showed no androgenic or antiandrogenic activities, nor were observed degenerative, inflammatory alterations and did not trigger systemic toxicity on the animals (Ferreira et al., 2016).
Although several studies presented in the scientific literature for B. tomentosa, including pharmacological studies and ethnomedicinal reports, there are no studies that approach the physical, chemical and biochemical characterization of this plant species fruits.On this perspective, the present work aims to evaluate the physical and physicochemical characterization of B. tomentosa fruits collected in the central and southern regions of the Tocantins state.

Plant material
The analyzed fruits were randomly collected from ten matrices in two regions of the Tocantins State, in the municipalities of Gurupi (southern region, samples 1, 2 and 3) and Palmas (central region, samples 4 and 5).The collects were carried out in 2013 between the months of July to Dctober; when the plant reaches its peak of productivity.The fruits of B. tomentosa were harvested manually in the first hours of the morning, packed in plastic bags and thermal boxes and sent to the Laboratory of Post Harvest Physiology of Fruits and Vegetables, in the Food Science Department (UFLA).The fruits were washed in distilled water, selected by their state of conservation and absence of defects caused by pests and manually reduced, being separated into three replicates (each replicate formed by twenty fruits).

Physical-chemical and biochemical analysis
The MONDLTA CR-400 colorimeter was used to perform the color analysis, with determination in the COE mode L* a* b*.The variables a* and b* were used to calculate the C* value (chromaticity) and ºh (Hue angle) (MacGuire, 1992).
Following the methodologies proposed by the Association of Dfficial Analytical Chemists (Association of Dfficial Analytical Chemistry, 2005), the determination of centesimal composition, soluble solids, titratable acidity and pH were performed.The humidity was determined according to the gravimetric technique (in a ventilated oven), the ethereal extract fraction was evaluated in an intermittent Soxhlet extractor using hexane as extracting solvent.The Kjeldahl (semimicro) method was used for protein determination and the 6.25 factor was applied to convert to protein the total nitrogen content.The ash fraction was determined by gravimetry in a muffle oven at 550 °C until constant weight and the glycidic fraction (carbohydrate content) was obtained by difference (Association of Dfficial Analytical Chemistry, 2005).
The total energetic value (TEV) was calculated by the sum of the calories (kcal) provided by carbohydrates, lipids and proteins, multiplying its values in grams by water factors 4 Kcal, 9 Kcal and 4 Kcal, respectively (Onstituto Adolfo Lutz, 2008).
The gross fiber determination was made by acid hydrolysis by the gravimetric method, according to the methodology described by Kamer & Ginkel (1952).Soluble pectin content was determined according to the technique standardized by McCready & McComb (1952) using a colorimetric method, based on hydrolyzed pectin reaction with galacturonic acid and carbazole, the results being expressed in mg of polygalacturonic acid 100 g -1 of fruit pulp.The total pectin content was obtained according to Bitter & Muir (1962), with the results expressed in g 100 g -1 of fruit pulp.The total sugars determination was performed by the colorimetric method according to Dische (1962), with the results expressed in g 100 g -1 of fruit pulp.
On order to determine the Vitamin C levels two methods of extraction were used.On the first method, an oxalic acid (0.5%) solution was used, and 50 mL of this solution were added to 5 g of the sample.The mixture was then triturated in polytron and homogenized on a stirrer for 30 minutes and filtered on filter paper.On the second extraction method, 50 mL of a metaphosphoric acid (1%) solution were added to 5 g of the sample.The resulting mixture was triturated in polytron and homogenized on a stirrer for 3 minutes.After 5 minutes centrifugation at 3000 rpm the supernatant was filtered on filter paper.The quantification of vitamin C in the extractions resulting solutions were performed by colorimetric method according to Strohercher & Henning (1967), with the results expressed as mg of vitamin C per 100 g of fruit pulp.
The contents of phenolic compounds were determined from the extracts obtained by adding 40 mL of an aqueous methanol solution (50% v/v) to 5 g of the sample.The mixture was stirred for 60 minutes (50 rpm), and then centrifuged for 15 minutes at 14000 rpm and the supernatant filtered.The total phenolics quantification was performed according to Waterhouse (2002), using the Folin Ciocalteau reagent.The results were expressed in grams of gallic acid equivalents per 100 grams of fresh pulp (g EAG 100 g -1 ).

Statistical analysis
The experimental design was completely randomized with three repetitions.The data were submitted to variance analysis and the means were compared by the Tukey test at 5% probability.All the analyses were made using the software SOSVAR (Ferreira, 2011).

Results and discussion
The obtained results for the color coordinates L* and the colorimetric indexes C* and ºh are presented in Table 1.The obtained values for the brightness (L*) and chromaticity (C*) were below pure white ( 100), what characterizes fruits with low light intensity and more opaque coloring.
A small variation was observed in relation to chromaticity for pulps and fruits with values between 14.36 to 17.27 and 15.56 to 18.89, respectively.Characterizing their little intensity colorations.As for the tonality (ºh), for both pulp and fruits, it can be inferred that it tends to yellow with shades variation from 98 to 110 ºh.The matrices data of (L*), (C*) and (ºh) analyzed demonstrate that the B. tomentosa fruits present a yellow-orange coloration.
The B. tomentosa fruits presented ºBrix variable from 22.33 to 25.33, as can be observed in Table 2.
The centesimal composition and caloric value of the analyzed B. tomentosa fruits pulps are presented in Table 3.
B. tomentosa fruit pulps presented high vitamin C content, ranging from 1265.59 to 3573.50 mg ascorbic acid per 100 g of pulp, as can be observed in Table 4.
The vitamin C levels presented by the B. tomentosa fruits are higher than those presented by fruits known to have high contents of this compound, such as the fruits of acerola (Malpighia emarginata) that presented levels ranging from 632 to 1457.69 mg 100 g -1 (Mezadri et al., 2008, Freire et al., 2013).The vitamin C concentration present in the B. tomentosa fruits is also higher than the levels in camu-camu fruits (Myrciaria dubia), 2061.04 and 1882 mg 100 g -1 (Alves et al., 2000;Rufino et al., 2011).These results demonstrate that the B. tomentosa fruits are among the fruits with higher amounts of vitamin C.
On relation to the contents of phenolic compounds presented by B. tomentosa fruit pulp, a variation of 2933.51 to 4200.33 mg GAE 100 g -1 was observed, as can be observed in Table 4.These levels cause this fruit, besides being a great source of vitamin C be also rich in phenolic compounds, considering the concentrations of phenolic compounds presented by known fruits.The amount of phenolic compounds from B. tomentosa fruit pulps were higher than those determined by Denardin et al. (2015) for fruits such as araçá, butiá, pitanga with orange, red and purple pulp, mulberry from cultivars Xavante and Cherokee cultive, with respective contents equal to 457.43, 359.50, 660.19, 457.43, 433.84, 799.80, 799.80 mg GAE 100 g -1 .These results were also higher than the values (expressed as mg GAE 100 g -1 ) found for several fruits of Amazonian and Brazilian savannah species, such as camu-camu (1400) Araticum (580), Cagaita (200), Jenipapo (651), Lobeira (1.166), Jabuticaba (1.15, methanolic extract 1.04 ethanolic), Guapeva (79.00, pulp and 474.10, husk), Cagaita (141.95),Cajú-do-cerrado (160.74),Gabiroba (1222.59)(Neves et al., 2012;Siqueira et al., 2013;Naspolini et al., 2016;Siqueira et al., 2017).However, the found values are similar to those reported for açaí fruit, with 3437 mg GAE 100 g-1 (Gordon et al., 2012), which is a known fruit rich in phenolic compounds.The high levels of vitamin C and phenolic compounds presented by the B. tomentosa fruits confer significant nutritional properties in view of the effects of these compounds on the human body.Ot is now known that vitamin C is involved in several biological processes, such as in the collagen and adrenaline synthesis, bile acids formation and some neurotransmitters (Baynes & Dominiczak, 2015).Phenolic compounds, due to their antioxidant properties, contribute to the reduction of the incidence of chronic and degenerative diseases (Mena & Llorach, 2017).They may also present anti-inflammatory, antimicrobial and anticarcinogenic activities (Mojzer et al., 2016).

Conclusion
Based on this study obtained data, the B. tomentosa fruits were potentially nutritious, with a significant number of sugars (carbohydrates), phenolic compounds and vitamin C.These fruits also had significant soluble solids contents, which may favor the degree of sweetness in relation to the acid.Thus, the fruits under study can be characterized as acid, slightly sweet, and of little yellow coloration.
*mesocarp and endocarp; **only the pericarp; ***CV = Coefficient of variation; Averages followed by the same letter, in the columns, do not differ by the Tukey test (p <0.05).
Averages followed by the same letter in the columns do not differ by the Tukey test (p <0.05); *Equivalent in citric acid; **CV = Coefficient of variation.

Table 4 .
Vitamin C and total phenolic content of Buchenavia tomentosa fruits samples.
Averages followed by the same letter in the columns do not differ by the Tukey test (p <0.05); *CV = Coefficient of variation.

Table 3 .
Humidity content, ethereal extract, gross protein, gross fiber, ash, glycidic fraction and total energetic value (TEV) of the Buchenavia tomentosa fruits pulp.Averages followed by the same vertical letter do not have significant difference by the Tukey test (p <0.05); *CV = Coefficient of variation.