Isolado proteico de sementes de cumaru [Amburana cearensis (Allemao) A. C. Smith] uma fonte alternativa de proteínas vegetais na alimentação

Abstract

The need to minimize health problems related to consumption of animal food and the significance of providing evidence for the richness of Caatinga biodiversity called attention to the search for new sources of plant protein in wild plants. Amburana cearensis is an underutilized species of legume from Caatinga, with seeds rich in protein and high nutritional potential that prompted us to investigate their use as protein isolates, increasingly common in the food industry. Thus the aim of the present work was to obtain a protein isolate from these seeds (PIAc), to perform a biochemical and functional characterization as well as to assess the safety of use, comparing it with an already marketed protein isolate. Analyses were conducted to elucidate the optimal conditions for protein extraction, proximal and amino acid composition, amino acids chemical score, in vitro protein digestibility, detection of toxic and/or antinutritional factors of protein nature, antioxidant activity, functional properties and assessing toxicity . The optimal extraction conditions were with water, pH 9.0; 1:20 (w / v) for 20 min, followed by protein precipitation at pH 5.5. The PIAC showed 97.86 ± 0.96% protein, 0.38% lipids ± 0.03, 2.2 ± 0.07% ash and 3, 51 ± 0.27% carbohydrates. The gross and net yield of protein was 17.85 and 53.96%, respectively. The digestibility (58.26 ± 0.02%) and the chemical amino acid score (0.296) was similar to those of commercial soybean protein isolate. No lectins or antioxidant activity was detected in PIAc however the isolate showed trypsin (17.28 ± 0.07) and chymotrypsin inhibitors (11.7 ± 0.56 IU / mg protein). As to the functional properties, its solubility was 86.4 ± 4.7%; water absorption capacity, 3.08 ± 0.11 g water/g sample; oil absorption capacity, 2.98 ± 0.08 g oil/g sample; emulsifying activity/emulsion stability 53.79 ± 1.31 / 52.38 ± 0.0%; foaming activity/stability, 139.4 ± 11.06/ 64.86 ± 2.56% (T0 and 120 min.) and gelling lower concentration (MCG), 10%. All these properties,except that of absorbing water were superior to those of the soybean protein isolate. Regarding the toxicity, no hemolytic activity or acute toxicity was detected in PIAc. In the repeated dose toxicity assay, no changes were observed in weight gain, food intake, hematological parameters or in histopathology of organs. Aparently irrelevant changes were found in some biochemical parameters in PIAc as well as in the commercial soybean protein isolate. Thus, we conclude that PIAc has a high nutritional and functional potential to be introduced in the food industry, showing no significant signs of toxicity. This is a very promising bioproduct, which requires further study, but draws attention to the great underexploited richness of Caatinga.