Caracterização bromatológica e avaliação de compostos bioativos presentes na batata da serra (Ipomoea Convolvulácea L.) produzida na Chapada Diamantina-BA

Abstract

One of the main problems faced by individuals in developing countries is food shortage. Therefore, regional extractive sources are the alternative found by the local population in order to supply the nutritional need demanded by the body. The Mountain Potato (Ipomoea Convolvulácea L.) is a native tuberous root derived from the mountainous regions, which has been consumed by the population of Chapada Diamantina (BA) and the tourists for decades. The present study had as its objective the evaluation of the microbiological, bromatological and biochemical qualities of the Mountain Potato (Ipomoea Convolvulácea L.) in natura and its respective flours. The fractions evaluated were the peel of the mountain potato in natura (CBS), pulp in natura (PBS), as well as the respective flours of the pulp and peel (FPBS and FCBS). The bromatological analysis followed the official methodologies of the Adolfo Lutz Institute and of AOAC. The water content of the pulp in natura was of 96,83% and 92,66% for CBS. The content of ash found for the flours were of 8,10% for FPBS and 7,74% for FCBS, and for CBS and PBS 1,35% and 0,50% respectively. The PBS showed the lower carbohydrate content, 2,38%, followed by CBS, FCBS and FPBS, with their respective quantities: 4,24%, 75,05% and 86,36%. The concentration of total fibers in increasing order were 14,44%, 22,39%, 34,21% and 47,91%, respectively, for the CBS, PBS, FPBS and FCBS fractions. The same increasing order of concentration was found for the insoluble and soluble fiber of the mountain potato. The values found for soluble fraction were 2,04% for CBS, 2,52%, 3,82% and 6,60% for PBS, FPBS and FCBS, respectively. For the insoluble fraction, the percentage of fiber was 8,71% for CBS, 17,35% for PBS, and 27,35% for FPBS, a lower value than that found for FCBS, 39,03%. The higher contamination index was found in samples of CBS, predominating in the three classes of microorganisms studied, with contents of 105 UFC.g-1 for mesophils, 104 UFC.g-1 for Bacillus Cereus and 106 UFC.g-1 for mould and yeast. For the fractions PBS, FPBS and FCBS, the levels found were below the limits established by the Brazilian legislation. In the statistical treatment applied between the peel fraction and its respective flours, a 5% significant difference was found for mould and yeast, however the same was not found for pulp and its flour, which, despite not differing between each other, presented safe levels on the microbiological point of view, with 103 and 101 UFC.g-1 respectively. Regarding the content of Bacillus Cereus the CBS presented higher content of 104 UFC.g-1, followed by FPBS and FCBS, with contamination index of 103 UFC.g-1 and the PBS with 102 UFC.g-1. The lower content of mesophils were shown on the fractions of PBS, FCBS and FPBS, at the rate of 103 UFC.g-1 and higher rates at 105 UFC.g-1. Regarding the phenolic compounds content and the antioxidant activity of peel and pulp extracts from the lyophilisated mountain potato and its respective flours, it was verified that the flour made from the potato peel, obtained in stove at 50°C (FCBSE) presented the higher content of total phenolic compounds (CFT), equivalent to 29,24 mg of Gallic acid by 100g, followed by the pulp of the lyophilisated mountain potato (PBSL), peel of lyophilisated mountain potato (CBSL) and flour of the mountain potato oven dried (FPBSE), with their respective concentrations at 5,37mg, 3,86mg and 3,41mg of Gallic acid by 100g. In the antioxidant activity, performed through the DPPH method, the AA % did not present any significant differences between the fractions PBSL, CBSL, FPBSE for the Turkey test at 5% significance. The AA % were, respectively 19,86%, 11,00% and 22,87%. There was a significant difference for this assay, only between FCBSE and the other samples, where the percentage of AA was of 88,78%, corroborating with the higher content of phenolic compounds presented for the same fraction evaluated. Considering the antioxidant activity by the oxidation method regarding the beta-carotene:linoleic acid system, there was no significant difference in the AA % among samples, however the CBSL presented the highest activity (25,91%). The antioxidant activity of PBSL was the lowest (19,32%) and above that was FCBSE (21,85%) and FPBSE (22,53%). When the efficacy of the methods regarding the samples studied were compared, no significant difference was found, through the analysis of the pulp fraction, lyophilised or submitted to oven drying. The higher nitrate content was found in PBS, followed by its flour, with content of 124,33 and 114,77 mg.100g-1 of dry matter. The fraction of the peel and its flour presented a low concentration of this anti-nutritional compound, with 39,77 and 30,77 mg.100g-1 respectively. The highest tannin concentrations were shown in the fraction of the mountain potato peel, with its flour being responsible for presenting a higher content 10,13 mg.100g-1 and the low tannin concentration was found in PBS, 1,25 mg.100g-1 . Considering the above-mentioned, it is possible to conclude that the quantification of the phenolic compounds, the confirmation of the antioxidant activity, the low glycemic index, the satisfactory content of soluble, insoluble and total fibers, the microbiological quality presented by the pulp and its flour and the richness of the existent nutrients, as well as the absence of anti-nutritional factors in the mountain potato will all contribute to increase the tendency for the consumption of safe and nutritious food, capable of supplying the nutritional needs of the population that consumes rhizome. Additionally, there is an added value to the raw material, with the benefits brought by the extracts used in the food industry, in the manufacture of attractive convenience products, such as fruit juices, milky drinks enriched with mountain potatoes, nectar, flours, sweets and other food products that are among the most appropriate for development in the local reality.