Study of the physical and physicochemical characteristics of fruits of the licuri palm ( Syagrus coronata ( Mart . ) Becc . ) found in the Atlantic Forest of Minas Gerais , Brazil

The Atlantic Forest covers an extensive area of the Brazilian territory and shows great variation in climate, soil, fauna and flora. Native fruit species of this biome have been explored for several purposes, including human consumption in natura or as juices, jams and jellies (Lorenzi et al., 2006). These fruit species are an alternative to improve the supply of nutrients in the population (Pilla & Amorozo, 2009). However, some species are still underutilized due to lack of scientific and technical studies on their nutritional value (Kinupp & Barros, 2004; Rockenbach et al., 2008).


Introduction
The Atlantic Forest covers an extensive area of the Brazilian territory and shows great variation in climate, soil, fauna and flora.Native fruit species of this biome have been explored for several purposes, including human consumption in natura or as juices, jams and jellies (Lorenzi et al., 2006).These fruit species are an alternative to improve the supply of nutrients in the population (Pilla & Amorozo, 2009).However, some species are still underutilized due to lack of scientific and technical studies on their nutritional value (Kinupp & Barros, 2004;Rockenbach et al., 2008).
Fruit consumption plays an important role in human nutrition, contributing to the increase in life expectancy and prevention of chronic non-communicable diseases, especially due to the presence of minerals, vitamins and dietary fiber (Cardoso et al., 2013b).Furthermore, the protective effect exerted by fruit is attributed to the presence of compounds capable of capturing free radicals (antioxidants), highlighting vitamins, phenolic compounds and carotenoids (Betoret et al., 2011).
Syagrus coronata belongs to the botanical family Arecaceae and is one of the main native palm species of the Atlantic Forest.
The fruit is a fibrous drupe with ovoid and fleshy endoderm.While green, it has liquid endosperm which becomes solid in the ripening process, giving rise to the kernels.When ripe, the pulp (exocarp and mesocarp) presents a light yellow to orange coloring, depending on the maturation stage.Ripe fruits have yellow, sticky and sweet pulp (Drumond, 2007).
Although the licuri palm has played a role in the eating habits of the rural population for generations, information in literature on its nutritional value is scarce.The limited information available refers to its proximate composition, physicochemical composition and some vitamins in fruits from northeastern Brazil, where it is widely used in the manufacture of couscous and coconut candy, the oil is used in cooking, and the kernels serve for both human consumption as well as use in poultry feed (Rufino et al., 2008;Santos et al., 2012).
Given the above, our study sought to analyze the physical and physico-chemical characteristics, proximate composition, and concentration of carotenoids, vitamin C, vitamin E and minerals in licuri fruits found in rural Viçosa, Minas Gerais.

Collection and preparation of the samples
The fruits analyzed were collected in March 2013, in the municipality of Viçosa (latitude 20º 45' 14" S and longitude 42º 52' 44" W), Minas Gerais, Brazil.Samples were collected in five different rural locations, which characterized the five repetitions.In each repetition approximately 1.5 kg of fruits from at least three different plants were used for obtantion of the pulp and 2.5 kg for obtantion of the kernels The samples were transported from the harvest site to the laboratory, protected in styrofoam boxes, within two hours after collection.The fruits were washed under tap water to remove dirt and then dried with paper towels.Pulp of the licuri fruit (exocarp and mesocarp) was manually separated from the rest of the fruit (endocarp and kernel) with the aid of a spatula, while the kernel was broken with the aid of a hammer and spatula, separating it from the fruit endocarp and mesocarp.
Next, the pulp and kernel were homogenized separately in a food processor (Philips  , RI 7625, Brasil), packaged in polyethylene bags wrapped in aluminum foil and stored in a freezer (-18 ± 1 °C) until performing the analyses.

Physical characterization
Measurements of length and diameter were obtained for 20 fruits using a digital caliper (Mitutoyo,M5,Brazil). Individual direct weighing of the total fruit mass (FM) and edible portion mass (EP), of the pulp and of the kernel was performed on a semi-analytical balance (Gehaka, BG 2000, Brazil).Then the yield of the edible part of the pulp and kernel was calculated using the following equation: (EM/FM) x 100.

Chemical analyses
The chemical analyses were performed, in three repetitions, at the Food Analysis and Vitamin Analysis Laboratories of the Department of Nutrition and Health, Federal University of Viçosa, Brazil.Titratable acidity (TA) was analyzed by volumetric neutralization and soluble solids (SS) by refractometry, pH by direct potentiometry (Instituto Adolfo Lutz, 2005), moisture by gravimetric analysis after oven drying (SP Labor  , SP 200, Brazil) at 105 °C, ash by gravimetry after burn in a muffle furnace (Quimis,318,Brasil) at 550 °C, proteins by the micro-Kjeldahl method, lipids by gravimetry after ethyl ether extraction using soxhlet and total dietary fiber (TDF) by non-enzymatic gravimetry (Association of Dfficial Analytical Chemists, 2010).Carbohydrates were calculated as the difference using the equation: [100 -% moisture -% lipids -% protein -% TDF -% ash].The total energetic value was estimated considering the conversion factors of 4 kcal g -1 of protein or carbohydrate and 9 kcal g -1 of lipids (Frary & Johnson, 2005).

Extraction and analysis of carotenoids and vitamins
Preparation and analysis of carotenoids and vitamins were performed in five repetitions using recently validated methods (limits of detection and quantification, tests of repeatability and recovery) in our laboratory for the analysis of fruits from the Brazilian Cerrado (Cardoso et al., 2013a).
During collection, extraction and analysis, fruits were protected from light to prevent the loss of vitamins and carotenoids.For the extraction of carotenoids and vitamins, the following reagents were used for analysis: acetone, petroleum ether and glacial acetic acid (Vetec, Brazil).For analysis of the compounds the following HPLC grade reagents were used: hexane, isopropanol, ethyl acetate, methanol and acetonitrile (Tedia, Brazil).
Analysis of carotenoids and vitamin C were carried out in a High Performance Liquid Chromatography system (HPLC) (Shimadzu, SCL 10AT VP, Japan) composed of a high-pressure pump (LC 10AT VP), autosampler with 500 µL loop (SIL-10AF), and diode array detector (DAD) (SPD-M10A).In the analysis of vitamin E, an HPLC system was used (Shimadzu, SCL 10AD VP, Japan) composed of a high-pressure pump valve for a low pressure quaternary gradient (LC 10AD VP), autosampler with 50 µL loop (SIL-10AF), and fluorescence detector (RF-10A XL).
The amount of vitamin A was calculated according to the recommendations of the Institute of Medicine (2011), wherein 1 Retinol Activity Equivalent (RAE) corresponds to 1 μg of retinol; 12 μg of β-carotene; 24 μg of other pro-vitamin carotenoids.

Vitamin C
Ascorbic acid (AA) and dehydroascorbic acid (DHA) were extracted in a buffer solution (3% metaphosphoric acid, 8% acetic acid, 0.3N sulfuric acid and 1 mM EDTA) (Campos et al., 2009).Then DHA in the sample was converted to AA using dithiothreitol (Pinheiro-Sant' Ana et al., 1998).For anlaysis of AA the chromatographic conditions proposed by Campos et al. (2009) were used, in the same HPLC system used for carotenoids.The column used was Lichrospher 100 (250 × 4 mm, 4 μm i.d.), equipped with a guard column (Phenomenex DDS, 4 mm × 3 mm); mobile phase composed of ultrapure water containing 1 mM NaH 2 PD 4 , 1 mM EDTA and pH adjusted to 3.0 with H 3 PD 4 , with isocratic elution at a flow rate of 1.0 mL minute -1 .The run time was approximately 8 minutes and the chromatograms were obtained at 245 nm.The DHA concentration was calculated using the equation: DHA concentration = AA concentration after conversion -AA concentration before conversion.

Determination of minerals
Minerals (P, K, Ca, Mg, Zn, Mn, Fe, Cu, Na, Cr, Se and Mo) were extracted according to Gomes & Dliveira (2011), using a solution of nitric acid and perchloric acid (4:1, v/v).The sample suspension was heated to 80 °C followed by gradual increase up to 200 °C, until the extract reached crystalline staining, and was then withdrawn to cool at room temperature.The crystalline extract was cooled and the volume was completed to 25 mL with deionized water (Gomes & Dliveira, 2011).The obtained solution was used to read the concentration of minerals by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) (Perkin Elmer, Dptima 8300).
Two multielement standard solutions (MESS) were prepared in 100 mL flasks, due to the different concentrations of minerals in the fruits.MESS 1 was prepared for Cr, Se, Mo, Zn, Cu, Fe and Mn.MESS 2 was prepared for Na, P, Mg, Ca and K.In order to quantify the minerals, analytical curves with six points were constructed using mineral standards purchased from Merck  (Brazil).For construction of the curves increasing volumes of MESS 1 (0 to 2 mL) and MESS 2 (0 to 20 mL) were used, completed to 50 mL with distilled water.The maximum concentration of elements in the multielement standard solutions is shown in.

Calculation of the potential of the licuri fruit as a nutrient source
The potential nutritional contribution of the licuri fruit was estimated based on the Recommended Dietary Allowance (RDA) for adult men between 19 and 30 years old according to recommendations of the US Institute of Medicine (2011).The fruit portion was calculated according to the Food Guide for the Brazilian Population (Brasil, 2008) considering the caloric density, where portions of pulp and kernel were equal to 70 and 100 kcal, respectively.
The fruit was classified as a "source" of nutrients when supplying 5-10% of the Dietary Reference Intake (DRI), as a "good source" when supplying 10-20% of the DRI and "excellent source" when supplying over 20% of the DRI (Philippi, 2008).

Experimental design and statistical analysis of the data
A completely randomized design was used with five replicates for analysis of carotenoids and vitamins, and three repetitions for physico-chemical analysis and proximate composition.
Descriptive statistics (mean, standard deviation and range of parameters) were used for analysis of the obtained data.To evaluate the linearity range of the analytical standards, data obtained for the peak areas was used to calculate the coefficient of correlation (R 2 ).Statistical analysis was performed using the SAS software (Statistical Analysis System), version 9.2 (2008), licensed to the UFV.

Results and discussion
In the present study we assessed the nutritional value of licuri fruits Syagrus coronata collected in the wild environment.Since they were spontaneously propagated native plants, they may present high genetic variability (Miller & Gross, 2011).Furthermore, to evaluate the real composition of the fruits and the method in which they are ingested by the population, in our study there was no control of environmental factors (soil, light, ventilation, water availability), which are known to interfere with nutrient concentrations (Bezerra, 2003;Vallilo et al., 2005).
The absence of studies on the licuri fruit made it difficult to compare data obtained in this study with other results.Moreover, it demonstrates the importance of our study and reliable analysis methods used to perform the research.

Physical characterization
The licuri fruit is a fibrous drupe, with ovoid shape, consisting an envelope surrounding the fruit (exocarp).The edible pulp of the fruit, of orangish-red color is the mesocarp.The seed is composed of the endocarp which surrounds the kernel.Between the woody endocarp and the seed is the pellicle, called the tegument (Figure 1).The pulp constitutes the major fraction of the licuri fruit (54.5%), while the kernel accounts for only 39.6% (Table 1).Dimensions of the licuri fruit found were greater than fruit harvested in Mairi, in the state of Bahia, which presented average length and diameter of 2.0 and 1.4 cm, respectively (Crepaldi et al., 2001).

Chemical characterization
The kernel showed no SS, however the value found in the pulp, as well as its TA, were lower than those found by Miranda (2011) (Table 2).
In the present study, moisture of the pulp and kernel were similar to those observed by Crepaldi et al. (2001) who reported values of 77.4 g 100g -1 and 28.6 g 100 g -1 , respectively.The concentrations of TDF, lipids, proteins and ash were similar to those found by Crepaldi et al. (2001) in the state of Bahia and in Paraíba by Miranda (2011), both also collected from the Atlantic Forest.
The values found for ash in kernels of the licuri fruit in the present study were similar to the kernels of other fruits of the botanical family arecácea, the jelly palm (Butia yatay L.) found in the northern region of the state of Minas Gerais, and the African oil palm (Elaeis guineensis Jacq) from the state of Paraíba, which presented concentrations of 1.80 g 100 -1 (Faria et al., 2008) and 1.70 g 100 -1 (Bora et al., 2003), respectively.
The calorific value of the kernel and the concentration of TDF in the pulp showed to be superior to those of fruits commonly known as good sources of these compounds, for example, coconut (Cocos nucifera L.) which has a calorific value of 406 Kcal 100 -1 and the peach palm (Bactris gasipaes L.) which has a TDF concentration equal to 4.3 g 100 -1 (Universidade Estadual de Campinas, 2011;Rodriguez-Amaya et al., 2008).These results indicated that the licuri fruit is a good option for individuals who need to gain weight.However, for individuals with overweight its consumption should be monitored.

Quantitative composition
There are few reports in literature on the presence of carotenoids and vitamins in licuri fruits (Crepaldi et al., 2001;Miranda, 2011), but they differ with regards to the analysis methods used in our study, making it difficult to compare the results.
The main component of vitamin C in the licuri fruit was AA, found only in the pulp.The content in the present study corresponded to 60% of the concentration observed by Miranda (2011), who found values of 4.30 mg 100g -1 in fruits collected in the Brazilian state of Paraíba.Regarding the concentration of vitamin E, α-, β-, γ-tocopherols and tocotrienols were identified, highlighting β-tocotrienol as the main component found in the kernels.
Although the kernel presented the highest concentration of vitamin E, they were not considered a source, since only 2.8% of the compounds encountered were in the form of α-tocopherol.However, we emphasize the importance of other tocopherols and tocotrienols found in the pulp, since they can prevent or minimize the damage caused by free radicals associated with diseases such as cancer, arthritis, cataracts, and aging (Sen et al., 2010).The pulp, although it had a total vitamin E concentration less than the kernel, showed a high α-tocopherol concentration (486.62 μg 100 -1 ).This compound represented 89.5% of the entire concentration found in the pulp, but insufficient to be considered a source of this vitamin.Values are expressed in fresh matter (mean of ten repetitions ± standard deviation).nd: not detected.Sganzeria (2010), in a study conducted in Rio Grande do Sul, did not detect the presence of tocopherols in kernels in any species, although the pulp presented 426.00 μg 100 -1 of total tocopherols, equivalent to 81% of the concentration found in our study.A direct relationship was observed between concentrations of vitamin E and lipids in the kernels and pulp of the licuri fruit.

Concentration of minerals
In the present study the main minerals in the pulp were K, Fe and Mn, while in the kernel were P, K, Mg, Fe, Zn and Mn.Se was not found in any of the samples, while Cr was found only in the pulp (Table 4).Miranda (2011) observed Zn concentrations in the pulp and kernels of licuri fruits from the state of Paraíba (3.74 and 4.92 mg 100 -1 , respectively), higher than those found in this study.Licuri fruits from the Brazilian Northeast showed Fe concentrations (pulp: 1.48 mg 100 -1 , and kernels: 1.19 mg 100 -1 ) lower than those observed in the present study (Miranda, 2011).

Potential contribution of licuri fruit to meet nutritional recommendations
The potential contribution of fractions from the licuri fruit to meet the recommendations of vitamins and minerals for adult men (19 to 30 years old) are presented in Table 5.
Aproximately, 77 and 20 g, respectively, are needed to provide the pulp (70 kcal) and kernel (100 kcal) portions.The pulp was considered a source of carbohydrates and good source of fiber.Considering the recommendation of vitamin A (Institute of Medicine, 2011), pulp of the licuri fruit showed to be an excellent source of this vitamin, contributing to 64.9% of the recommendation.Licuri fruits were not considered sources of vitamin C, since the quantities found were very low.
Although the licuri kernel presented a high concentration of vitamin E, this was not considered a source because it contains only 36.48 μg 100 -1 in the form of α-tocopherol, which is currently the only component considered for calculation of the recommendations (Müller et al., 2010).
The kernel was considered an excellent source of Cu, while the pulp was considered a source of Zn.The kernel was also considered a potential source of Fe, while the pulp an excellent source of this nutrient.
Both the pulp and kernel of the licuri fruit were considered excellent sources of Mn, even surpassing the DRIs for intake of these nutrients, but without exceeding the untolerable level (UL) for intake by adults between 19 to 30 years old (UL = 11 mg/day).Pulp of the licuri fruit showed to be a source of Cr and excellent source of Mo.

Conclusions
The present study shows the first results on the concentration of nutrients in these fruits in the Atlantic Forest region, and can help to fill a gap in information regarding its nutritional composition.
The licuri fruits analyzed in this study exhibited high pulp yield.Their nutritional value was considered excellent due to the presence of vitamin C and E, carotenoids and minerals, and it was an excellent source of vitamin A, Cu, Fe, Mn, Cr and Mo.The caloric density was higher than that of many fruits consumed in Brazil, and it also presented high concentrations of total dietary fiber and lipids.The nutritional value and wide availability of this fruit make it an important tool for reducing food insecurity and improving nutrition of individuals residing near the Atlantic Forest, especially in rural households, since its consumption is part of the eating habit of these families., 2011), based on a portion of pulp and kernel which provide 70 and 100 kcal, respectively (Brasil, 2008), nd: not detected.**(α-tocoferol).

Figure 1 .
Figure 1.Anatomy/cross section of a mature licuri fruit found in the Atlantic Forest of Minas Gerais, Brazil.

Table 2 .
Chemical characteristics and caloric density of licuri fruits (Syagrus coronata (Mart.)Becc) encountered in the Atlantic Forest of Minas Gerais, Brazil.

Table 3 .
Concentration of carotenoids and vitamins in licuri fruits (Syagrus coronata (Mart.)Becc) found in the Atlantic Forest of Minas Gerais, Brazil.
Values are expressed in fresh matter (mean of five repetitions ± standard deviation).nd:not detected.

Table 4 .
Concentration of minerals in licuri fruits (Syagrus coronata (Mart.)Becc) found in the Atlantic Forest of Minas Gerais, Brazil.
Values are expressed in fresh matter; mean of 3 repetions; data presented in mean (rounded to two decimal places) ± standard deviation; nd: not detected.

Table 5 .
Potential contribution of licuri fruits (Syagrus coronata (Mart.)Becc) found in the Atlantic Forest of Minas Gerais, Brazil, for supplying of daily nutrient recommendations*.
*Calculated based on the Recommended Dietary Allowance of minerals for adult men between 19 and 30 years old (Institute of Medicine