Physico-Chemical Characterization and Antioxidant Activity of Miconia Ciliata (rich.) Dc Infrutescences in Two Maturation Stages

is the biggest genus of Melastomatacea Juss, a family with pantropical distribution. The present study aimed to conduct the physico-chemical characterization and evaluate the antioxidant capacity of Miconia ciliata infrutescences. Analyses of pH, titratable acidity, total sugars, soluble pectin, total phenol, vitamin C, monomeric anthocyanins, antioxidant activity (DPPH) and color (L, C, ºh) were conducted. The pH increased as acidity decreased, while soluble solids, total sugars and soluble pectin increased and total phenol, vitamin C, antioxidant activity and clarity increased as maturation advanced. Monomeric anthocyanins were only detected in mature infrutescences, while the green ones presented more vivid color. The hue angle changed from green to purple from the green-mature to mature infrutescences, respectively. infrutescences have significant amounts of total phenols, are source of vitamin C and present sensory and functional appeal.


Introduction
Miconia is the biggest genus of Melastomatacea Juss, a family with pantropical distribution, however most of species is found in the Neotropical region [1,2]. It is composed by approximately 150 genera and 4500 species, with 66 genera and 1370 occurring in Brazil, representing the sixth most diverse family in the country [3]. Miconia species are generally described by collectors like shrubs or small trees (4-5m). Many species present a great variability of height and may attain from 10 to 30m [4]. The fruit is a berry regularly finalized by the lacinium of cup or thalamus of hypantoand species present deciduous chalice [5]. The family lacks data on the industrial, food and/or medicinal importance, since only few compounds were isolated [6]. The study of little known species may reveal information that support the generation of income and employments for local communities due to the correct exploration of biodiversity, as well as help on reducing deforestation [7] and provide information for more specific studies in several areas like food and pharmaceutical industries. Then, the physical and chemical characterization of plants is important for the evaluation of quality, technological classification, provision of secure information to determine the nutritional value, yield, processing operations to be used and the product lifespan [8].
In the state of Pará the consumption of Miconia ciliata (Rich.) by children that walk along streams is common. Fruits are generally known as "uvinha", "chumbinho" and "canela-de-veado". The lack of scientific data on physico-chemical parameters and antioxidant potential of infrutescences of Miconia ciliate make the studies greatly important given the relevance of such species for the Brazilian flora and communities. In this sense, the present study aimed to characterize physico-chemical traits and evaluate the antioxidant potential of Miconia ciliate in two maturation stages. Green-mature and mature fruits were collected in Vila do Apeú (1º17'00.1"S 47º58'50.9"W), municipality of Castanhal, state of Pará, Brazil, and transported to the Laboratory of Postharvest of Fruits and Vegetables of Federal University of Lavras, where pH, titratable acidity, soluble solids, total sugars, soluble pectin, color (L, C, and h), total phenols, vitamin C, monomeric anthocyanin and antioxidant activity were evaluated using the method DPPH.
The analyses are described as follows: pH was determined using a pHmeter Tec -3MP (TECNAL) according to the technique of AOAC [9]. The determination of titratable acidity was conducted according to Instituto Adolfo Lutz [10]. Results were expressed in percentage of citric acid. The digital portable Refractometer PAL-1 (ATAGO) was used to determine the soluble

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solids. Results were expressed in percentage of soluble solids [9]. Total sugars were determined by the method of Antrona [11]. Results were expressed in mg.100g-1. The extraction of pectin soluble substances was conducted according to the technique described by McCready & McComb [12] and the determination was made by Bitter & Muir [13] method. Results were expressed in mg of galacturonic acid. 100g-1 of fruit. The total phenols were made by Folin-Ciocalteau method [14]. Results were expressed in mg of galic acid equivalent (AGE).100g-1 of fruit. The content of ascorbic acid was determined by Strohecker & Henning [15] method. Results were expressed in mg of ascorbic acid.100g-1of fruit. The analysis of anthocyanins was conducted according to the method of differential pH proposed by Giusti & Wrolstad [16]. Results were expressed in mg.100g-1 of sample. The determination of antioxidant activity was conducted by means of the method of sequestration of radicals DPPH by antioxidants, according to Brand-Williams, Cuvelier & Berset [17], adapted by Rufino et al. [18]. Results were expressed in % of sequestration of free radical (% FRS). The coloration was performed using a Minolta colorimeter CR-400 in the model CIE L*a*b*, as well as illuminant D65. The variables L*, angle hue (h°) and chroma (C*) were considered. All analyses were conducted in triplicate and expressed as means ± standard deviation by means of the software MS Excel (Microsoft Office 2010 Professional). The pH (Table 1) of ripe ( Figure 1) infrutescences was higher, while acidity was higher in green infrutescences. Soluble solids, total sugars and soluble pectin were higher in ripe infrutescences. Phenolic compound content and antioxidant activities determined by DPPH were higher in green-mature infrutescences. Table 1 presents the reduction of vitamin C content as maturing advances. In relation to anthocyanins, they were found only in ripe infrutescences. Regarding the color, the green-mature infrutescences of Miconia ciliata were clearer and presented more vivid color, while in relation to the hue angle, the green-mature was green and the ripe was purple.
In general during maturing of fruits there is an increase of pH and decrease of total acidity resultant from the reduction of organic acids [19]. According to the classification of Franco and Landgraf [20], foods with pH equal or inferior to 4.0 may be classified as acid and very acid, respectively, in this sense greenmature and mature infrutescences of Miconia ciliata may be considered very acid and acid, respectively. The sugar content, besides determining the degree of sweetness, also provides information on the technological potential, microbiological susceptibility and together with acidity is correlated with the parameter of flavor quality. The sweetness of fruits depends on the soluble solids, since most of them are sugars [21]. In relation to pectin, one of the main components of primary cell wall, it is frequently described as a highly complex polysaccharide rich in galacturonic acid [22]. It represents about one third of the cell wall structure [23] and its solubilization is related to the fruit softening. The phenolic compound content reduced as maturing advanced. Some authors associated the reduction of antioxidant capacity along maturing with the decrease of phenolic compounds and other bioactive compounds [24,25]. Neves et al. [26] also observed the reduction of vitamin C along maturing in 8 different Amazon fruits. Considering the daily need of vitamin C intake for women (75mg) and children (45mg) [26], 100g of Miconia ciliata infrutescences can attend this need, thus demonstrating that they represent sources of vitamin C. The presence of anthocyanins only in ripe infrutescences may be explained by its synthesis and degradation of chlorophylls that occur parallel to the development and maturing of fruits [27,28]. Miconia ciliata infrutescences have sensory and functional appeal, with significant amounts of total phenols and vitamin C. However the study of anti-nutritional factors is recommended since it is a non-conventional food.