Characterization and evaluation of the antioxidant capacity of freeze-dried pulp enriched with aqueous extract of tamarind (Tamarindus indica) seed

Author(s)

Danilo Santos Souza

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia de Alimentos
• Defense date: 2015-05-25

Examining board members

Helena Teixeira Godoy; Cláudia Hoffmann Kowalski; Cristiano Augusto Ballus; Daniele Rodrigues; Marcelo Alexandre Prado

• Advisor: Helena Teixeira Godoy

Abstract

The seed of tamarind, responsible for the most amount of bioactive compounds of the fruit, has only been marginally exploited for food purposes. The aim of the present study was to characterize the fruit (pulp and seeds) regarding their antioxidant properties as well as produce and characterize a lyophilized product made of pulp and aqueous extract of freeze-dried tamarind seed, taking advantage of the functional properties (antioxidant) and at the same time maintaining acceptable sensory characteristics. Tamarind fruits were acquired from three different states of Brazil (MG, SP e BA). The lots were obtained in 2012 and 2013. The fatty acid profile and tocopherols seeds were also evaluated. The best conditions for the extraction of bioactive compounds, from tamarind seed in aqueous phase, was set by Central Composite Rotational Design (CCRD). The best extraction condition consisted of: 80 s of trituration with a ratio (w/v) of 1:3 (seeds:water), were the residue material was extracted twice under the same conditions. The extracts were added to the pulps at the concentrations [1] (0.3%), [2] (1.15%) and [3] (2.0%), relative to the in natura hydrated pulp, to made the mixture (mix). The content of phenolic compounds (FT), antioxidant capacity (FRAP, DPPH, ABTS and ORAC) and hemolytic activity were determined for the pulps, seeds, freeze-dried seed extracts and freeze-dried mix of pulp and fruit seed extract. The results were dependent on the origin of the fruit. The pulp enrichment were satisfactory with substantial increase of the antioxidant capacity (ABTS?) by 1910, 1300 and 937% for mixtures of MG [3] SP [3] and BA [3], respectively. The samples acquired from São Paulo and Bahia had the highest rates of hemolysis, especially for those in which high amount of extract was added, reaching 98.8% of cell lysis for the SPsample [2] Lot 2, and 98.5% for the BA sample [1] lot 1. Ten fatty acids from the seed oil were identified and quantified by GC-FID technique, and 9 of them were confirmed by GC-MS. The oil seed presented 75% and 25% of unsaturated and saturated fatty acids, respectively. Linoleic acid (C18:1n-6, cis) was the major fatty acid (ranging from 145 to 270 mg.g-1dry mass), followed by oleic acid (31 e 83 mg.g-1d.m) and palmitic acid (21 to 47 mg.g-1d.m). Isomers of tocopherols (?, ?, ? e ?-tocopherol) were detected and quantified, where ? and ?-tocopherols were present in higher amount (27 and 25 mg.kg-1d.m., respectively). Sensory analysis for the difference from the control test showed that the concentrations 1.15 and 2% of the added extract have altered the appearance attributes, aroma and taste of the nectar, however, this change was also related to the origin of the fruits. On the other hand, the acceptance test showed high variability in scores according to the assessors profile and a trend in reducing the nectar acceptance when increasing the seed extract concentration (AU)

• FAPESP's process: 12/06806-4 - Characterization and evaluation of biological and antioxidant activity properties of freeze-dried pulp enriched with bioactive compounds from the seed of tamarind (Tamarindus indica)
• Grantee: Danilo Santos Souza
• Support Opportunities: Scholarships in Brazil - Doctorate