Comparison of chickpea varieties, optimization of hydrolysates production, peptide identification and evaluation of biomarkers for type 2 diabetes in the application of a value-added tortilla.

Acevedo Martinez, Karla Ameyalli

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https://hdl.handle.net/2142/113133 Copy

Description

Title

Comparison of chickpea varieties, optimization of hydrolysates production, peptide identification and evaluation of biomarkers for type 2 diabetes in the application of a value-added tortilla.

Author(s)

Acevedo Martinez, Karla Ameyalli

Issue Date

2021-07-01

Director of Research (if dissertation) or Advisor (if thesis)

González de Mejía, Elvira

Department of Study

Food Science & Human Nutrition

Discipline

Food Science & Human Nutrition

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• bioactive compounds
• bioactive peptides
• chickpea
• Cicer arietinum
• chickpea snacks
• chickpea processing
• functional properties
• enzymatic hydrolysis
• hydrolysate
• bromelain
• type 2 diabetes
• α-amylase
• α-glucosidase
• DPPIV inhibitor
• protein fortification

Abstract

Chickpea (Cicer arietinum) is one of the most produced and consumed pulses worldwide. In preclinical and clinical studies, chickpea has shown health benefits including antioxidant capacity, as well as antifungal, antibacterial, analgesic, angiotensin I-converting enzyme inhibition, hypocholesterolemic, anticancer, and anti-inflammatory properties. On the other hand, in the U.S. diabetes mellitus (DM) affects around 10-13% of the population and it is the 7th leading cause of death. Pulses such as common bean have shown potential inhibitory activity for type 2 diabetes biomarkers. The objective of this research was to compare five varieties of chickpea (Sierra, Nash, Billy bean, Myles and a commercial sample), identify the peptides obtained with pepsin-pancreatin digestion, and evaluate their potential as modulators of biochemical markers for type-2 diabetes (T2D). In addition, it was aimed to produce, by the optimization in the production of hydrolysates using bromelain, a functional ingredient that could be applied to a maize tortilla product and test the bioactivity of the final product. The first part of the research was focused on the extraction, isolation and characterization of proteins of ground raw, precooked, and cooked chickpea from five varieties of chickpea. Then, hydrolysates were obtained by simulated digestion with pepsin-pancreatin, resulting peptides were sequenced with LC-MSMS and biomarkers for T2D [α-glucosidase, α-amylase and dipeptidyl peptidase (DPPIV) inhibition] were analyzed. The highest bioactivity was selected as output variable in the optimization process. In addition, response surface methodology was used to optimize the production of chickpea isolated protein hydrolysates using bromelain. Protein profiles from the five chickpea varieties showed fractions of convicilin (>70 kDa), 7S vicilin (43 -53 kDa), 11S legumin (35 kDa) and lectins (30-32 kDa) in raw varieties. Albumin fractions 2S (20-26 kDa) were still present in most varieties after 2 h of heat treatment. DPPIV IC50 values using digestive enzymes were better (0.17-2.21 mg/mL) in raw chickpea than in cooked chickpea. α-glucosidase inhibition was highest (32%-66% at 10 mg protein/mL) in precooked chickpea hydrolysates. α-Amylase in only one variety (raw Billy bean) showed good inhibition of 69% at 0.100 mg/mL. After optimization, bromelain hydrolysates showed a DPPIV inhibition of 94% for Sierra variety cooked for 15 min with 1:10 E/S ratio and hydrolysis time of 60 min. The optimization model found an inverse relationship between heat treatment time and inhibition response. For hydrolysis time and enzyme substrate ratio, the inhibitory activity increased as these factors also increased. Per variety, hydrolysis time affected positively Sierra, Nash and commercial varieties, but did not show a greater impact on Myles or Billy bean. Peptides with DPPIV inhibition were present from albumin fractions (EVLSEVSF) with molecular mass of 908.44 Da and high hydrophobicity (12.2 Kcal * mol -1); and from legumin (VVFW, FDLPAL) with 549.29 and 674.36 Da, respectively. Peptides in the composite bromelain hydrolysates produced with the optimal conditions had high hydrophobicity (7.21-27.05 Kcal * mol -1) and wide range of pI (3.12-11.13), being soluble at pH from 2 to 12; sequence FDLPAL was also found. In the second part of the research, the optimized conditions were used to produce a composite bromelain hydrolysate from chickpea isolated protein that were applied to white and blue maize tortillas at different ratios (5%, 10% and 15%, w/w), to be compared to tortillas with no added hydrolysate (0%). In terms of soluble proteins, the lowest fortification level increased soluble protein in 105% (8 g/100 g tortilla). Physical comparison included color analysis (l* a* b*, hue angle and ∆E), texture (hardness, cohesiveness, and puncture force) and moisture changes in fresh and stored tortillas (48 h and 7 days). Chemical analyses included LC-MS-MS for peptides sequencing of the composite hydrolysate produced, testing the fortified maize tortillas for soluble protein determination and characterization using SDS-PAGE electrophoresis, and DPPIV inhibition before and after simulated gastrointestinal digestion. Peptides in the hydrolysates had high hydrophobicity (7.97 - 27.05 kcal * mol -1) and pI (5.18 - 11.13). Molecular docking of peptides showed interaction with DPPIV with an energy of affinity of -5.8 kcal/mol for FDLPAL in comparison with vildagliptin (-6.2 kcal/mol). Physical analysis of fortified tortillas showed changes in color (∆E) for both white and blue tortillas at all fortification levels compared to the control. In fresh tortillas, moisture content was higher for the 10% fortification ratio compared to the control tortillas (p <0.05). After 7 days of storage, the presence of the hydrolysate from 5% to 15% allowed the tortillas, blue and white, to remain with constant moisture content overtime as when fresh. Texture analysis showed higher hardness values in fresh white tortilla at 10 and 15% fortification ratios (27.47 ± 3.18 and 25.58 ± 4.01 kg/s, respectively) in comparison to the no fortified tortilla (13.56 ±1.66 kg/s) (p <0.05). Fresh blue maize tortillas showed difference only at 15% fortification level resulting in lower hardness values (16.71 ± 2.63 kg/sec). After 7 days of storage, 10% fortification ratio showed the highest hardness values in both color tortillas (32.38 ± 1.12 kg/s white 21.53 kg/s blue) being higher than the control (p <0.05). DPPIV inhibition of white maize tortilla increased from 11% (fresh control) to 91% (15% fortification); for blue tortilla from 26% to 95%. After simulated digestion, there was not difference (p <0.05) between blue or white maize tortillas for DPPIV inhibition. In conclusion, different varieties of chickpea from both desi and kabuli have similar protein profiles and soluble protein concertation. Albumin fractions 2S (20-26 kDa) are resistant to heat treatments in all varieties. In raw chickpea digests, Billy bean (kabuli) had the best IC50 for DPPIV inhibition (0.17 mg of soluble protein/mL). After optimization, Sierra variety (kabuli) had the best DPPIV inhibition (93%). Therefore, high DDPIV inhibition can be obtained from chickpea bromelain hydrolysates using protein isolates, showing potential as ingredients in different food categories of a wide range of pH applications. DPPIV bioactivity in food products can be improved after application and can resist processing conditions similar to the ones described in this study. Further research is needed to analyze the acceptability of the physical and potential flavor changes as well as the clinical translation and results of these food applications.

Graduation Semester

2021-08

Type of Resource

Thesis

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http://hdl.handle.net/2142/113133

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Copyright 2021 Karla Acevedo Martinez

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