A Novel Insight into Screening for Antioxidant Peptides from Hazelnut Protein: Based on the Properties of Amino Acid Residues

This study used the properties of amino acid residues to screen antioxidant peptides from hazelnut protein. It was confirmed that the type and position of amino acid residues, grand average of hydropathy, and molecular weight of a peptide could be comprehensively applied to obtain desirable antioxidants after analyzing the information of synthesized dipeptides and BIOPEP database. As a result, six peptides, FSEY, QIESW, SEGFEW, IDLGTTY, GEGFFEM, and NLNQCQRYM were identified from hazelnut protein hydrolysates with higher antioxidant capacity than reduced Glutathione (GSH) against linoleic acid oxidation. The peptides having Tyr residue at C-terminal were found to prohibit the oxidation of linoleic acid better than others. Among them, peptide FSEY inhibited the rancidity of hazelnut oil very well in an oil-in-water emulsion. Additionally, quantum chemical parameters proved Tyr-residue to act as the active site of FSEY are responsible for its antioxidation. This is the first presentation of a novel approach to excavating desired antioxidant peptides against lipid oxidation from hazelnut protein via the properties of amino acid residues.

The Quality Characteristic and Fatty Acid Profile of Cold-Pressed Hazelnut Oils during Nine Months of Storage

Poland is one of the largest producers of hazelnuts in Europe; however, information regarding the storage of cold-pressed hazelnut oil is limited. Thus, the aim of this study was to determine the oxidative indices and fatty acid composition of oils from six hazelnut cultivars during 9 months of storage. At the beginning of storage, the hazelnut oils showed zero or very low oxidation values, which indicated the absence of initial triglyceride hydrolysis and fatty acid oxidation. Acid values increased with storage time, which was statistically significant, ranging from 0.17 to 0.34 mg KOH/g oil. The peroxide value in the first 5 months of storage was undetectable, whereas after 9 months the oils showed a slight increase in oils obtained from the ‘Olbrzym z Halle’ cultivar, followed by the ‘Barcelonski’ cultivar, at 3.39 and 2.15 meq O2/kg, respectively. The lipid content of the kernels was very stable under storage conditions. Total monounsaturated fatty acid content exhibited the highest proportion, while saturated fatty acids (SFAs) had the lowest content over the entire storage period. The percentage of polyunsaturated fatty acids showed a small decrease during storage, but was not statistically significant; therefore, polyunsaturated fatty acid remained stable. The percentage of monounsaturated fatty acids decreased by approx. 1.6%, thus the percentage of SFA increased by approx. 13.7% during 9 months of storage. The oil yield ranged from 69% for nuts from the ‘Nottinghsamski’ cultivar to 75% from the ‘Webba Cenny’ and ‘Barcelonski’ cultivars.

An experimental study on the effect of concentration of green nanoadditives on the tribological properties of the biolubricants

The paper aims to introduce a sustainable solution in the field of lubrication science. A green nano additive, hexagonal boron nitride (h-BN) is mixed with two biofriendly natural oils (avocado oil and hazelnut oil) and the tribological properties of the nanolubricants are evaluated on a four-ball tribotester. The nanoparticles are less than 100 nm in diameter and are added in varying concentrations of 0-1 wt.%. The tribological properties are evaluated as per ASTM D4172 and the stability of the nanoparticles is measured for a period of 24 hours using a double beam spectrophotometer. The UV spectroscopy results indicate the nanoparticles are stable after the sonication process and sediment very less after 24 hours. The antiwear properties of both natural oil improve with the increase in the concentration of h-BN nanoparticles. The maximum improvement in the wear properties is observed at 1 wt.% and is equal to 19.5% and 36.55% for avocado oil and hazelnut oil respectively. The improvement in the antiwear properties are ascribed to the different nanolubrication mechanisms: tribofilm formation, non-direct contact phenomenon, and entrapment of nanoparticles between wear agglomerates.

Methylation levels of LEP and POMC genes after intervention with dietary folate and hazelnut oil in the lipid profile of overweight women

BackgroundObesity contributes to several cardiometabolic diseases, such as dyslipidemia, as a result of an unhealthy lifestyle and genetic factors. The methylation profile of genes involved in appetite control and metabolism, such as LEP (leptin) and POMC (proopiomelanocortin) and altered lipid levels can contribute to obesity, and these epigenetic changes have been associated with the effects of diet composition. The objective of this study was to evaluate the methylation levels of LEP and POMC genes and lipid profile values after intervention with dietary folate and hazelnut oil in overweight women.MethodsDouble-blind, placebo, controlled intervention study with 40 overweight adult women. Participants were randomized into four groups for 8 weeks: G1, 300 g of vegetables and 191 µg / day of folate and hazelnut oil; G2, 300 g of vegetables and 191 µg / day of folate and placebo; G3, 300 g of vegetables and 94 µg / day of folate and hazelnut oil; G4, the individuals were only accompanied. In addition to the levels of methylation, food consumption, anthropometric measurements, biochemical variables of lipid profile were evaluated.ResultsAfter the intervention, the participants presented reduction in the methylation levels of the studied genes in the three intervention groups in the LEP gene: G1 (p = 0.00), G2 (p = 0.00) and G3 (p = 0.00); in the POMC gene: G1 (p = 0.01), G2 (p = 0.02) and G3 (p = 0.01), and in the lipid profile, G1 reduced the levels of LDL-c (p = 0.04), HDL-c (p = 0.00) and Triglycerides (p = 0.04); in G3 there was a reduction in total cholesterol levels (p = 0.00), LDL-c (p = 0.00) and HDL-c (p = 0.00), and in G4 there was a reduction in total cholesterol values (p = 0.00), LDL-c (p = 0.00), HDL-c (p = 0.00) and triglycerides (p = 0.00), and also, an association in G2 between the POMC methylation levels with triglycerides (p = 0.00).ConclusionThe study provided evidence of a normocaloric intervention with dietary folate and hazelnut oil supplementation on the methylation levels of LEP and POMC genes and the role they can play in lipid metabolism.Trial registrationISRCTN, NCT04523532. Registered 21 August 2020, https://clinicaltrials.gov/ct2/show/NCT04523532