Nutraceutical properties of isolated starch, phytochemical compounds and bioactive peptides from pigmented chickpea cultivars influenced by cooking or germination process.

Chickpea (Cicer arietinum L.) is the third most consumed pulse worldwide and a potential functional ingredient due to its nutritious composition and bioactive compounds. The aim of this investigation was to evaluate the potential of ten pigmented chickpea cultivars as ingredients in functional foods using cooking or germination to enhance bioactive compounds with health effect. The investigation was performed in five steps in order to evaluate the potential of ten chickpea cultivars differing in seed coat color (black, brown, green, red and cream). The first approach was to evaluate chickpea flours on the techno-functionality, chemical composition and nutritional properties related to starch and protein. The colored chickpeas flours showed higher content of bioactive compounds as total phenolics (TPC), β-glucans, resistant starch and higher protein digestibility corrected amino acid score (PDCAAS) compared with the commercial chickpea Blanco Sinaloa (cream seed coat). The limiting amino acids in chickpea flours were Trp, Thr and Met+Cys, whereas PDCAAS ranged from 0.59 to 0.82. Correlation analysis showed a possible interaction between TPC and starch which influenced thermal properties and starch digestion. The principal component analysis (PCA) showed several differences among the chemical compositions, starch digestions and seed protein qualities. Moreover, starch is the major component of chickpea seeds; therefore the wet-milled chickpea starches were studied on physicochemical, functional and in vitro starch digestion properties. The yield of chickpea starches ranged from 19.22 to 30.06%; total starch and amylose contents in the starches varied from 87.14 to 96.02% and 25.05 to 35.26%, respectively. Gelatinization properties (DSC, RVA) showed large differences among starches. The rapidly digestible (RDS), slowly digestible (SDS) and resistant (RS) gelatinized starch fractions varied from 56.34 to 59.15%, 33.22 to 35.43% and 6.42 to 9.22%, respectively. The predicted glycemic indexes (pGI) of native and gelatinized chickpea starches ranged from 65.52 to 66.10 and 74.39 to 75.74, respectively. A close correlation among the viscosity characteristics of isolated starches and the starch digestion fractions were found after PCA analysis. The starches properties were not dependent of the seed coat coloration of the cultivars. Overall, the results suggest that the starches of the array of chickpeas studied may hold a potential for the development of functional foods especially due to its functional properties, medium glycemic index, high SDS and RS contents. Additionally, the fate of phytochemicals during cooking and germination was evaluated. The 10 chickpea cultivars were soaked and cooked for the phytochemical evaluation. The compounds were identified by HPLC-IT-MS and quantified by HPLC-UV-ELSD. In Milán-Noris, A.K. 7 the raw chickpea seeds, eleven compounds were identified among cultivars; soyasaponin βg (m/z 1068) and biochanin A (m/z 285) were the principal compounds found. The thermal process caused significant (p≤0.05) reduction in flavonoids content but only minor lost of total saponins content. Besides, the effect of the germination process on phytochemicals of four chickpea cultivars (black, cream, green and red) was evaluated. Chickpea cultivars were germinated during five day at 24ºC. Eight isoflavonoids and soyasaponin βg were identified in germinated chickpea cultivars. However, genotype showed a significant effect on the profile and content of isoflavonoids during germination process. Phytochemical content increased significantly during germination process in all chickpea cultivars. Lastly, the anti-inflammatory effects of peptides and isoflavonoids associated to the unabsorbed digestion of protein concentrates from cooked or germinated (G.ICC5613 and Blanco Sinaloa) chickpea cultivars were investigated. The simulated gastrointestinal digestion released isoflavonoids and peptides (