María Concepción García

Composition and characterization of soyabean and related products

Soyabean contains about 48 to 50% proteins. Among these, storage proteins are predominant. 7S and 11S globulins are two storage proteins that constitute 80% of the total protein content in soyabean. Moreover, there are other less abundant storage proteins such as 2S, 9S, and 15S globulins. In addition to globulins, enzymes, protease inhibitors (Kunitz and Bowman-Birk), lectin, and other complete the soya protein content. Different methods exist to characterize soya proteins. These methods involve (1) an isolation of proteins from soya commercial products and (2) the use of analytical techniques for protein determination. Soya proteins may interact with other soya components such as minerals, phytic acid, ascorbic acid, and fiber. These interactions, which depend on soya processing and treatment, can decrease the bioavailability of minerals and proteins. Swelling, solubility, viscosity, and capacity to form a gel, an emulsion, or a foam are the main functional properties of soyabean. They are responsible for the wide use of soya in industrial processes.

CE‐TOF MS analysis of complex protein hydrolyzates from genetically modified soybeans – A tool for foodomics

A CE‐TOF MS proteomic approach was applied for the analysis of hydrolyzates from complex soybean protein mixtures. After CE‐TOF MS method development, the new approach provided the simultaneous analysis of more than 150 peptides from the soybean protein fraction soluble in ACN‐water (80/20 v/v). The method is fast (about 30 min of analysis per sample) and is characterized by a relatively low running cost. The approach was used to study the substantial equivalence between a genetically modified variety of soybean compared with its traditional counterpart. No significant differences were found between the two studied soybeans based on the protein fraction studied. The capacity of the CE‐TOF MS method to analyze complex mixtures of peptides in short times opens interesting possibilities in the growing Foodomics area.

Vegetable foods: A cheap source of proteins and peptides with antihypertensive, antioxidant, and other less occurrence bioactivities

Despite less explored than foods from animal origin, plant derived foods also contain biologically active proteins and peptides. Bioactive peptides can be present as an independent entity in the food or, more frequently, can be in a latent state as part of the sequence of a protein. Release from that protein requires protein hydrolysis by enzymatic digestion, fermentation or autolysis. Different methodologies have been used to test proteins and peptides bioactivities. Fractionation, separation, and identification techniques have also been employed for the isolation and identification of bioactive proteins or peptides. In this work, proteins and peptides from plant derived foods exerting antihypertensive, antioxidant, hypocholesterolemic, antithrombotic, and immunostimulating capacities or ability to reduce food intake have been reviewed.

Novel strategy for the revalorization of olive (Olea europaea) residues based on the extraction of bioactive peptides

This work proposes a new strategy for the revalorization of residual materials from table-olive and olive oil production based on the extraction of bioactive peptides. Enzymatic hydrolysates of olive seed protein isolate were prepared by treatment with five different proteases: Alcalase, Thermolysin, Neutrase, Flavourzyme and PTN. Although all hydrolysates presented antioxidant properties, Alcalase was the enzyme that yielded the hydrolysate with the highest antioxidant capacity. All hydrolysates showed antihypertensive capacity, obtaining IC50 values from 29 to 350 μg/ml. Thermolysin was the enzyme which yielded the hydrolysate with the highest ACE-inhibitory capacity. Hydrolysates were fractionated by ultrafiltration showing a high concentration of short chain peptides, which exhibited significantly higher antioxidant and antihypertensive capacities than fractions with higher molecular weights. Peptides in most active fractions were identified by LC-MS/MS, observing homologies with other recognized antioxidant and antihypertensive peptides. Finally, their antioxidant and antihypertensive capacities were evaluated after in vitro gastrointestinal digestion.

In-depth proteomic analysis of banana (Musa spp.) fruit with combinatorial peptide ligand libraries

Musa ssp. is among the worlds leading fruit crops. Although a strong interest on banana biochemistry exists in the scientific community, focused on metabolite composition, proteins have been scarcely investigated even if they play an important role in food allergy and stability, are a source of biologically active peptides, and can provide information about nutritional aspects of this fruit. In this work we have employed the combinatorial peptide ligand libraries after different types of protein extractions, for searching the very low‐abundance proteins in banana. The use of advanced MS techniques and Musa ssp. mRNAs database in combination with the Uniprot_viridiplantae database allowed us to identify 1131 proteins. Among this huge amount of proteins we found several already known allergens such as Mus a 1, pectinesterase, superoxide dismutase, and potentially new allergens. Additionally several enzymes involved in degradation of starch granules and strictly correlated to ripening stage were identified. This is the first in‐depth exploration of the banana fruit proteome and one of the largest descriptions of the proteome of any vegetable system.

Identification of olive (Olea europaea) seed and pulp proteins by nLC-MS/MS via combinatorial peptide ligand libraries.

Different types of extraction protocols are described for identifying proteins in seed and pulp of olive (Olea europea), by employing both conventional extraction methods and capture with ProteoMiner as well as with in house-made combinatorial peptide ligand libraries (HM-CPLLs) at pH 7.4 and at pH 2.2. Thanks to the use of CPLLs, able to dramatically amplify the signal of low-abundance species, a quite large number of compounds has been indeed identified: 61 in the seed (vs. only four reported in current literature) and 231 in the pulp (vs. 56 described so far), the deepest investigation up to the present of the olive proteome. In the seed, it highlights the presence of seed storage proteins, oleosins and histones. In the pulp, the allergenic thaumatin-like protein (Ole e 13) was confirmed, among the other 231, as the most abundant protein in the olive pulp. The present research has also been undertaken with the aim of identifying proteins in olive oil and ascertaining the relative contribution of seed and pulp proteins in their presence, if any, in oils.

Identification of avocado (Persea americana) pulp proteins by nano‐LC‐MS/MS via combinatorial peptide ligand libraries

Avocado (Persea americana) proteins have been scarcely studied despite their importance, especially in food related allergies. The proteome of avocado pulp was explored in depth by extracting proteins with capture by combinatorial peptide ligand libraries at pH 7.4 and under conditions mimicking reverse‐phase capture at pH 2.2. The total number of unique gene products identified amounts to 1012 proteins, of which 174 are in common with the control, untreated sample, 190 are present only in the control and 648 represent the new species detected via combinatorial peptide ligand libraries of all combined eluates and likely represent low‐abundance proteins. Among the 1012 proteins, it was possible to identify the already known avocado allergen Pers a 1 and different proteins susceptible to be allergens such as a profilin, a polygalacturonase, a thaumatin‐like protein, a glucanase, and an isoflavone reductase like protein.

Evaluation of the Effect of Dietary Virgin Olive Oil on Blood Pressure and Lipid Composition of Serum and Low-Density Lipoprotein in Elderly Type 2 Diabetic Subjects

Dietary virgin olive oil may help to reduce blood pressure in hypertensive individuals, but little is known about the effect on type 2 diabetic patients. For the present study, 17 type 2 diabetic elderly subjects and 23 healthy elderly controls received a diet rich in virgin olive oil for 4 weeks. Blood pressure, biochemical parameters, low-density lipoprotein (LDL), and oxidized LDL lipids and fatty acids were measured. Systolic blood pressure was reduced after virgin olive oil consumption in both controls and diabetic patients. Although the biochemical parameters were not modified, the intervention protected LDL from oxidation and restored the levels of dihomo-gamma-linolenic acid (20:3, n-6) in serum cholesterol esters and phospholipids of diabetic patients. In conclusion, the present study provides new evidence of the effects of dietary virgin olive oil on blood pressure and LDL oxidation in type 2 diabetics. It is likely that the components responsible for the observed effects are the monounsaturated fatty acids and the presence of antioxidants in the oil, but this needs further investigation.

Estimation of the percentage of transgenic Bt maize in maize flour mixtures using perfusion and monolithic reversed-phase high-performance liquid chromatography and chemometric tools

The estimation of the percentage of transgenic Bt maize in maize flour mixtures has been achieved in this work by high-performance liquid chromatography using perfusion and monolithic columns and chemometric analysis. Principal component analysis allowed a preliminary study of the data structure. Then, linear discriminant analysis was used to develop decision rules to classify samples in the established categories (percentages of transgenic Bt maize). Finally, linear regression (LR) and multivariate regression models (namely, principal component analysis regression (PCR), partial least squares regression (PLS-1), and multiple linear regression (MLR)) were assayed for the prediction of the percentages of transgenic Bt maize present in a maize flour mixture. Using the relative areas of the protein peaks, MLR provided the best models and was able to predict the percentage of transgenic Bt maize in flour mixtures with an error of ±5.3%, ±2.3%, and ±3.8% in the predictions of Aristis Bt, DKC6575, and PR33P67, respectively.

HPLC-Q-TOF-MS Identification of Antioxidant and Antihypertensive Peptides Recovered from Cherry (Prunus cerasus L.) Subproducts

The processing of fruits, such as cherries, is characterized by generating a lot of waste material such as fruit stones, skins, etc. To contribute to environmental sustainability, it is necessary to recover these residues. Cherry stones contain seeds with a significant amount of proteins that are underused and undervalued. The aim of this work was to extract cherry seed proteins, to evaluate the presence of bioactive peptides, and to identify them by mass spectrometry. The digestion of cherry seed proteins was optimized, and three different enzymes were employed: Alcalase, Thermolysin, and Flavourzyme. Peptide extracts obtained by the digestion of the cherry seed protein isolate with Alcalase and Thermolysin yielded the highest antioxidant and antihypertensive capacities. Ultrafiltration of hydrolysates allowed obtaining fractions with high antioxidant and antihypertensive capabilities. HPLC-Q-TOF-MS together with bioinformatics tools enabled one to identify peptides in these fractions.