Screening and Mechanism of Novel Angiotensin-I-Converting Enzyme Inhibitory Peptides in X. sorbifolia Seed Meal: A Computer-Assisted Experimental Study Method.

Angiotensin-I-converting enzyme (ACE) inhibitors are used extensively to control hypertension. In this study, a computer-assisted experimental approach was used to screen ACE-inhibiting peptides from X. sorbifolum seed meal (XSM). The process conditions for XSM hydrolysis were optimized through the orthogonal experimental method combined with a database. The optimal conditions for ACE inhibition included an alkaline protease dose of 5%, 45 °C, 15 min and pH 9.5. The hydrolysate was analyzed by LC-MS/MS, and 10 optimal peptides were screened. Molecular docking results revealed four peptides (GGLPGFDPA, IMAVLAIVL, ETYFIVR, and INPILLPK) with ACE inhibitory potential. At 0.1 mg/mL, the synthetic peptides GGLPGFDPA, ETYFIVR, and INPILLPK provided ACE inhibition rates of 24.89%, 67.02%, and 4.19%, respectively. GGLPGFDPA and ETYFIVR maintained high inhibitory activities during in vitro digestions. Therefore, the XSM protein may be a suitable material for preparing ACE inhibitory peptides, and computer-assisted experimental screening is an effective, accurate and promising method for discovering new active peptides.

Harsh Sensitivity and Mechanism Exploration of an Antibacterial Peptide Extracted from Walnut Oil Residue Derived from Agro-Industrial Waste.

Walnut (Juglans regia L.) cake meal constitutes a significant amount of solid byproduct from the production of walnut oil, comprising more than 40% protein. However, it is usually not well utilized. Therefore, an antibacterial peptide was obtained by hydrolyzing walnut oil residue protein with pepsin based on the diameter parameters of the antibacterial zone in this research. The purified antibacterial peptide WRPH-II-6 was obtained by two-part purification (ultrafiltration and reversed-phase liquid chromatography) and possessed higher antibacterial activity against Escherichia coli (MIC = 1.33 mg/mL), Staphylococcus aureus (MIC = 0.33 mg/mL), and Bacillus subtilis (MIC = 0.66 mg/mL). The amino acid sequence of WRPH-II-6 was identified as TGSAVPSPRASATATMEMAAAMGLMPGSPSSVSAVMSPF, where the presence of a large proportion of hydrophobic amino acid residues, such as alanine, proline, and methionine, explained the marked antibacterial activity of WRPH-II-6. The harsh sensitivity experiment demonstrated that WRPH-II-6 retains the stability of antibacterial activity when exposed to broad-spectrum pH values, variable temperatures, and long-lasting UV irradiation. The antibacterial mechanism of the WRPH-II-6 peptide against S. aureus and B. subtilis involves nonmembrane disruption: the contact of anions and cations causes the folding and collapse of the bacterial cell membrane to achieve the inhibitory effect. The antibacterial mechanism against E. coli is membrane disruption, which markedly disrupts the bacterial cell membrane to achieve the bactericidal effect. Significantly, the walnut residual protein hydrolysate is a potent preservative and antibacterial agent.

Impact of UHT processing on volatile components and chemical composition of sea buckthorn (Hippophae rhamnoides) pulp: A prediction of the biochemical pathway underlying aroma compound formation.

The effects of ultrahigh-temperature sterilization (UHT) on the volatile components and chemical composition of sea buckthorn pulp (SBP) were evaluated firstly. UHT had significant effects on the volatiles of SBP (mainly occurring at 140 °C for 2 s and 4 s), in which 140 °C for 2 s resulted in a decrease of 3.48% and 14.60% in total volatiles and esters, and an increase of 6.73% in alcohols, while alcohols contents sharply decreased by 6.90% at 140 °C for 4 s. Moreover, 140 °C for 2 s and 4 s decreased the amino acid content by 35.39% and 29.75%, respectively, while UHT significantly promoted the increase of fatty acids, but only a small increase at 140 °C for 4 s. The speculation is that a large number of volatiles were formed during the 140 °C for 2 s and 4 s, mainly from amino acid reactions and lipid oxidation.

Roasting intervention for the volatile composition of three varieties of nuts originating from Torreya yunnanensis.

For the first time, the volatiles of three varieties of fresh and roasted Torreya yunnanensis nuts were investigated by solid-phase microextraction-gas chromatography-mass spectrometry. The results indicated that roasting had the greatest effect on the volatiles of millet capsules. Fresh nuts had many terpenes, esters, and aldehydes, while roasting led to the formation of pyrazines and furans. In subsequent work, short-term low temperature and small sample area exposed to high temperature had a large effect on the increase in some volatiles and was characterized by a green flavor, such as α-pinene, while ultrahigh-temperature (200 and 230°C) resulted in a decrease in the total volatiles with the generation of unpleasant flavors. Finally, the combination of 170°C for 40 min and slight crushing was found to be the best roasting conditions for samples by means of GC-MS and two-dimensional gas chromatography and time-of-flight mass spectrometry (GC × GC/TOF-MS). PRACTICAL APPLICATIONS: Torreya yunnanensis and its nuts have broad development prospects because of their wide use and rich nutrition. However, inappropriate processing and lack of attention to natural materials such as nuts and wood leads to their poor usage. In addition, volatile compounds make a major contribution to the nut aroma, which is an important indicator of their sensory quality. However, no one has applied roasting technology to Torreya yunnanensis nuts or studied the volatile compounds of the roasted nuts. This study revealed the changes in the composition and content of volatile compounds in Torreya yunnanensis nuts before and after roasting, and the influence of different process points, suggesting that they are key contributors to the development of the related products.