An Acad Bras Cienc (2020) 92(Suppl. 1): e20180757 DOI 10.1590/0001-3765202020180757 Anais da Academia Brasileira de Ciências | Annals of the Brazilian Academy of Sciences Printed ISSN 0001-3765 I Online ISSN 1678-2690 www.scielo.br/aabc | www.fb.com/aabcjournal AGRARIAN SCIENCES Nutritional assay Pereskia spp.: Running title: ORA-PRO-NOBIS: unconventional vegetable UNCONVENTIONAL VEGETAL Academy Section: Agrarian MELISSA G. SILVEIRA, CAMILA T.R. PICININ, MARCELO ÂNGELO CIRILLO, JULIANA M. FREIRE & MARIA DE FÁTIMA P. BARCELOS Sciences Abstract: Pereskia grandifolia Haworth (PGH) and Pereskia aculeata Miller (PAM) are recognized sources of proteins; dietary fiber; vitamins and minerals make this plant e20180757 leaves, raw, cooked, and braised, an important ally against protein and micronutrient deficiencies. One of the main problems is the presence of antinutritional factors that may interfere in the digestibility and bioavailability of some nutrients. The objective 92 was to evaluate the amino acid profile and the chemical score of the raw leaves and (Suppl. 1) 92(Suppl. 1) the effects of heating media and time on the total dietary fiber, minerals, trypsin inhibition, oxalic acid and tannins of leaves of PGH and PAM. The samples had similar amino acid profiles and total dietary fiber. With regard to antinutritional compounds, heating the leaves of PGH led to a decrease in trypsin inhibition, primarily after the first minutes of wet cooking. Oxalic acid and tannins predominated in both species. Considering the interaction with time, the variables related to iron and zinc minimized the tannin responses in PGH and PAM, respectively. Heating media and times interfered with the chemical components present in the leaves of Pereskia species and led to high antinutrient retention after heat treatment. Key words: Pereskia grandifolia Haworth, Pereskia aculeata Miller, oxalate, tannins, tryp- sin inhibitor, minerals. INTRODUCTION fiber levels (Moran & Zimmermann 1991, Rocha et al. 2008, Martinevski et al. 2013, Sobrinho et Two edible species of the genus Pereskia, P. al. 2015). grandifolia Haworth (PGH) and P. aculeata Miller Leaves are rich in compounds with (PAM), popularly known as ora-pro-nobis (OPN), antioxidant activity (Sim et al. 2010, Agostini- are recognized sources of proteins; dietary Costa et al. 2014, Almeida et al. 2014) dietary fiber fiber; vitamins A, B, and C; and minerals such as (Rocha et al. 2008, Takeiti et al. 2009, Almeida et calcium, zinc, and iron. These compounds make al. 2014), minerals, such as calcium, iron, zinc, this plant an important ally against protein manganese and magnesium (Albuquerque et al. and micronutrient deficiencies (Hęś et al. 2014, 1991, Girão et al. 2003, Takeiti et al. 2009, Oliveira et Almeida et al. 2014). al. 2013, Souza et al. 2016) and monosaccharides Raw, cooked, and braised OPN leaves are such as arabinofuranose, arabinopyranose, consumed by population. When dried, the leaves galactopyranose, galactopyranosyluronic can add nutritional value to bread dough and acid, rhamnopyranose and glucopyranose pasta or be used to create other acceptable and (Sierakowski et al. 1990). low-cost formulations with elevated protein and An Acad Bras Cienc (2020) 92(Suppl. 1) MELISSA G. SILVEIRA et al. Ora-Pro-Nobis: UNCONVENTIONAL VEGETAL One of the main problems in exploiting When associated with oxalates and tannins, vegetable leaves as a source of nutrients is the fibers may the bioavailability of minerals, the presence of antinutritional factors, such as such as calcium, zinc, magnesium and iron, trypsin inhibitors, oxalates, and tannins, among among others (Benevides et al. 2011). others. These compounds may be toxic and/or Considering that OPN leaves may be used interfere in the digestibility and bioavailability of as low-cost sources of proteins, minerals and some nutrients, such as proteins and minerals. fibers, and are relevant in preventing and/or The antinutritional factors should be treating malnutrition, the present study had two reduced or eliminated when possible. On objectives: to determine the amino acid profile one hand, heating food may improve some of proteins in the leaves of Pereskia grandifolia nutritional and sensory aspects; on the other Haworth and Pereskia aculeata Miller, and to hand, it results in the losses of some nutrients investigate the behavior of the antinutritional and antinutrients due to heating, leaching, and factors and the minerals under different heat complexation between substances, hindering treatments. their extraction and availability in the body (Correia et al. 2008, Pellegrini et al. 2010). Trypsin inhibitors can block the action of MATERIALS AND METHODS proteolytic enzymes and cause endogenous Plant material losses of essential amino acids, especially those Leaves of the ora-pro-nobis (OPN) species containing sulfur (Pisulewska & Pisulewski Pereskia grandifolia Haworth (PGH) and Pereskia 2000). Many researchers have reported that the aculeata Miller (PAM) were harvested from raw leaves of OPN can inhibit of trypsin (Almeida the Medicinal Plant Garden of the Agriculture et al. 2014) and the heating can eliminate the Department, UFLA. The leaves were cleaned trypsin inhibitors (Pompeu et al. 2014) under water, immersed in sodium hypochlorite Oxalic acid, present in higher amounts (200 ppm), washed with distilled water, and in green leafy vegetables (Oliveira et al. 2008, drained. Squena et al. 2009, Almeida et al. 2014) can bind to calcium and iron ions and interferes Sample preparation with the bioavailability of these minerals due One portion of the leaf samples from each to the formation of insoluble salts (Ferreira & species was kept raw for amino acid analysis and Arêas 2010). Ogbadoyi et al. (2006) observed a another portion was heated using various media 65% decrease in oxalate content in ingested and times for mineral, fiber, and antinutritional vegetable leaves after heating (100°C/5 min) compound analysis. and discarding the water, and others (Benevides The vegetables were cooked according to et al. 2013, Lisiewska et al. 2011) . domestic cooking practices. After optimizing the Tannins are able to complex with proteins cooking conditions, wet cooking (boiling) and and minerals, among other polymers, such as mixed cooking (braising) techniques were used, carbohydrate after the vegetables that contain according to the heat transfer media (Ornellas them are damaged, making these polymers 2007). The temperature was kept constant (96 ± unavailable to the human body (Delfino & 2°C). After the raw leaves were added to enough Canniatti-Brazaca 2010, Benevides et al. 2013). boiling distilled water (1:4, p/v), they were wet- cooked. The cooking time (1, 2.5, 5, or 10 min) An Acad Bras Cienc (2020) 92(Suppl. 1) e20180757 2 | 16 MELISSA G. SILVEIRA et al. Ora-Pro-Nobis: UNCONVENTIONAL VEGETAL was measured from the time when the water was determined by calculating the quotient of returned to a boil; then the cooking water was each essential amino acid (mg) contained in the discarded. Mixed cooking was done in 3 mL of test protein (g) divided by the same amino acid soybean oil to 50 g of sample for 1 and 2.5 min, in the reference protein, and then multiplying with the same implements and under the same by 100 (Young & Pellett, 1994). The percentage conditions as the wet-cooked leaves. of protein digestibility was corrected using the After cooking, the plant material was cooled protein digestibility percentages reported by in an ice bath and drained. A portion of the Almeida-Filho & Cambraia (1974) (77.7%) and samples was placed in an oven at 60°C and dried Takeiti et al. (2009) (75.9%) as a base, multiplied to less than 10% moisture content. The dried by the amino acid content of the protein. samples were ground to obtain a homogeneous powder (3 times/20 seconds) and stored in Bioactive analysis amber glass flasks until analysis. The total dietary fiber (TDF) and fractions were determined using the enzymatic-gravimetric Analyses performed method (Sigma®) according to the AOAC (2005). All chemical analyses were conducted in The minerals were analyzed according to triplicate and the results expressed in dry Malavolta et al. (1997) using an Atomic Absorption matter. The reagents used were obtained from Spectrometer. Sigma-Aldrich (USA) or Merck (Germany), and The extracts, diluted in 1:5 ratios, were the other chemical products were of analytical prepared according to Souza et al. (2011). A grade. supernatant was used in the enzymatic inhibition assays, and enzyme activity was determined Chromatographic analysis of amino acids and according to Erlanger et al. (1961). Enzymatic chemical score determination inhibition was obtained by determining the The amino acid profile of the proteins were line slopes (absorbance × time) of the activity determined using the Prates method (Prates assays of the control enzymes and enzymes 2002) with a weight equivalent to 20 mg of with inhibitor, and the absorbance values were crude protein. 1 mL of sample was filtered converted into μmol of product, using the molar through a Millex unit (0.22-mm pore diameter, extinction coefficient of BAPNA. 13-mm diameter) and placed into an automatic Oxalic acid (OA) was determined using sampler for subsequent injection into an amino the titration method (AOAC 1990); that is, hot- acid analyzer under the following analytical extracted in HCl and caprylic acid, precipitated, conditions: injection volume, 10 mL; oven and quantified by titration with potassium temperature, 60ºC; fluorescence detector, EX l permanganate. 350 nm, EM l 450 nm; separation column, Shim- The tannins (TAN), extracted with methanol pack Amino-Na; ammonia trap column, Shim- (80%) using the method describe by Swain and pack ISC-30Na. The amino acid profile was Hillis (1959) were measured by the colorimetry determined using one C18 column with 20 μL method according to AOAC (1990). injection volume, and an amino acid standard was used to construct the calibration curve. Statistical methodology To test the limiting amino acids, the A univariate statistical technique was used chemical score of the amino acids (Who 2002) to interpret the trypsin inhibitor levels with An Acad Bras Cienc (2020) 92(Suppl.