Effect of succinylation-assisted glycosylation on the structural characteristics, emulsifying, and gel properties of walnut glutenin.

In this study, we examined the effects of various sodium alginate (ALG) concentrations (0.2%-0.8%) on the functional and physicochemical characteristics of succinylated walnut glutenin (GLU-SA). The results showed that acylation decreased the particle size and zeta potential of walnut glutenin (GLU) by 122- and 0.27-fold, respectively. In addition, the protein structure unfolded, providing conditions for glycosylation. After GLU-SA was combined with ALG, the surface hydrophobicity decreased and the net negative charge and disulfide bond content increased. The protein structure was analyzed by FTIR, Endogenous fluorescence spectroscopy, and SEM, and ALG prompted GLU-SA cross-linking to form a stable three-dimensional network structure. The results indicated that dual modification improved the functional properties of the complex, especially its potential protein gel and emulsifying properties. This research provide theoretical support and a technical reference for expanding the application of GLU in the processing of protein and oil products.

Exploration of markers in oxidized rancidity walnut kernels based on lipidomics and volatolomics.

Walnut kernels are prone to oxidation and rancidity due to their rich lipid composition, but the existing evaluation indicators are not sensitive enough to promote their industrial development. This study aims to investigate the potential markers in oxidative rancidity walnut kernels using lipidomics and volatolomics. The results showed that the antioxidant capacity of walnut kernels significantly decreased after oxidation, with the decreasing of total phenolic content from 36276.34 mg GAE/kg to 31281.53 mg GAE/kg, the DPPH and ABTS free radical scavenging activity from 89.25% to 73.54%, and 61.69% to 43.73%, respectively. The activities of lipoxygenase (LOX) and lipase (LPS) increased by 6.08-fold and 0.33-fold, respectively. By combining volatolomics and chemometrics methods, it was found that significant differences existed in the content of hexanal, caproic acid, 1-pentanol, (E)-2-octenal, and 2-heptanenal before and after walnut kernel oxidation (VIP > 1). Based on the results of lipidomics, it can be concluded that the above five compounds can serve as characteristic markers for walnut kernel oxidative rancidity, mainly produced through glycerol phospholipid (GPL), glyceride, linoleic acid (LA), and α-linolenic acid (ALA) metabolism pathways. Possible mechanisms of lipid degradation in oxidized walnut kernels were also proposed, providing technical support for the storage, preservation, and high-value utilization of walnut kernels.

Optimization and characterization of chestnut shell pigment extract obtained microwave assisted extraction by response surface methodology.

The objective of this study is to find optimum conditions to valorize chestnut shell bioactive compounds with coloring pigments through microwave-assisted extraction. With this aim, response surface methodology with central composite design was used. Microwave power (800 W), extraction time (12 min) and solvent concentration (NaOH: 0.115 mol/L) were determined as the optimum conditions to maximize the responses like color value, total phenolic content and total antioxidant capacity. In the optimized extract (OE), characterization of brown melanin like pigments were assessed by Spectrophotometer, Fourier Transform Infrared Spectrometer and major phenolics were identified as; gallic acid, ellagic acid, protocatechuic acid, catechin, and epicatechin as 0.53, 0.48, 0.46, 0.46, 0.14 mg/g dried weight (dw) by High Performance Liquid Chromatography, respectively. In terms of antibacterial activity, OE inhibited the growth of Staphylococcus aureus. Consequently, chestnut shells were successfully processed into natural coloring agents that were possessing strong brown color properties as well as high bioactive potential.

Integrated metabolomic and transcriptomic dynamic profiles of endopleura coloration during fruit maturation in three walnut cultivars.

BACKGROUND: The color of endopleura is a vital factor in determining the economic value and aesthetics appeal of nut. Walnuts (Juglans) are a key source of edible nuts, high in proteins, amino acids, lipids, carbohydrates. Walnut had a variety endopleura color as yellow, red, and purple. However, the regulation of walnut endopleura color remains little known. RESULTS: To understand the process of coloration in endopleura, we performed the integrative analysis of transcriptomes and metabolomes at two developmental stages of walnut endopleura. We obtained total of 4,950 differentially expressed genes (DEGs) and 794 metabolites from walnut endopleura, which are involved in flavonoid and phenolic biosynthesis pathways. The enrichment analysis revealed that the cinnamic acid, coniferyl alcohol, naringenin, and naringenin-7-O-glucoside were important metabolites in the development process of walnut endopleura. Transcriptome and metabolome analyses revealed that the DEGs and differentially regulated metabolites (DRMs) were significantly enriched in flavonoid biosynthesis and phenolic metabolic pathways. Through co-expression analysis, CHS (chalcone synthase), CHI (chalcone isomerase), CCR (cinnamoyl CoA reductase), CAD (cinnamyl alcohol dehydrogenase), COMT (catechol-Omethyl transferase), and 4CL (4-coumaroyl: CoA-ligase) may be the key genes that potentially regulate walnut endopleura color in flavonoid biosynthesis and phenolic metabolic pathways. CONCLUSIONS: This study illuminates the metabolic pathways and candidate genes that underlie the endopleura coloration in walnuts, lay the foundation for further study and provides insights into controlling nut's colour.

Identification of oxygenated triacylglycerols in pistachio nuts' lipids by reverse-phase high-resolution-liquid chromatography-ESI mass spectrometry.

Hydroxy- and peroxy-triacylglycerols are common products of lipid peroxidation formed during oil storage or heating or as enzymatic oxidation product of arachidonic acid as signaling molecules in mammals. In this study, oxygenated triacylglycerides (TAG) were identified in pistachio oil based on reverse phase(RP), high-performance liquid chromatography coupled with electrospray ionization and mass spectrometry (HPLC- ESI -MS). 20 novel lipid plant metabolites, classified based on their fragment spectra into a hydroxy (TAG-OH), an epoxy (TAG-O), and hydroperoxide (TAG-OOH) groups. We believe that this class of compounds has been for the first time observed as genuine secondary plant metabolites in a natural source in this case pistachio lipids of dietary relevance.

Sensitive ELISA and lateral flow immunoassay for the detection of walnut traces in processed food and working surfaces.

Walnut represents one of the most allergenic nuts that can be found as a hidden allergen. In this study, sandwich ELISA and lateral flow immunoassay (LFIA), based on the determination of Jug r 1, were developed to detect walnut. Cross-reactivity was only found with Pecan nut among a panel of 88 food ingredients tested. ELISA and LFIA could detect 0.25 and 0.5 µg/g of walnut protein in complex food matrices spiked with walnut extract, respectively. Furthermore, walnut was detected in blended (chocolate) and incurred foods (ice cream and bread) added with ground walnut at levels of 0.5 and 1.5 µg protein/g by ELISA and LFIA, respectively. LFIA could also detect 0.1 µg of walnut protein in working surfaces. ELISA displayed acceptable precision and high recovery (71-97 %) and both tests were robust. This study shows that developed ELISA and LFIA are reliable tools to be applied in allergen control programs.

Development and application of mass spectrometric molecular networking for analyzing the ingredients of areca nut.

Areca nut (Areca catechu L.) is commonly consumed as a chewing food in the Asian region. However, the investigations into the components of areca nut are limited. In this study, we have developed an approach that combines mass spectrometry with feature-based molecular network to explore the chemical characteristics of the areca nut. In comparison to the conventional method, this technique demonstrates a superior capability in annotating unknown compounds present in areca nut. We annotated a total of 52 compounds, including one potential previously unreported alkaloid, one carbohydrate, and one phenol and confirmed the presence of 7 of them by comparing with commercial standards. The validated method was used to evaluate chemical features of areca nut at different growth stages, annotating 25 compounds as potential biomarkers for distinguishing areca nut growth stages. Therefore, this approach offers a rapid and accurate method for the component analysis of areca nut.

Changes in nutritional, health benefits, and pharmaceutical potential of raw and roasted tropical almond (Terminalia catappa Linn.) nuts from Nigeria.

Tropical almond (Terminalia catappa Linn.) is highly distributed within the tropics, but appears rather underutilized in developing countries like Nigeria. Specifically, relevant information regards the nutritional, health benefits, and pharmaceutical potential of roasted T. catappa nuts remains scanty. Comparing both raw and roasted T. catappa nuts should provide additional information especially from product development and potential commercial prospect standpoints. The changes in nutritional, health benefits, and pharmaceutical potentials of raw and roasted T. catappa nuts were, therefore, investigated. Whereas the raw T. catappa nuts obtained significantly (p < 0.05) higher protein, ash, moisture, crude fiber, as well as vitamins C, and B1-3 compared to the roasted ones, some contents like carbohydrates, energy, vitamin A, calcium, manganese, zinc, hydrogen cyanide, as well as oxalate would noticeably change (p < 0.05) after the roasting process. Twenty phytochemicals were identified in both raw and roasted samples with the concentrations of quinine, ribalinidine, sapogenin, flavan-3-ol and tannin significantly reduced, while catechin seemed enhanced upon roasting. Promising drug-likeness, pharmacokinetic properties, and safety profiles could be predicted among the phytochemicals. Overall, roasting T. catappa nuts should enhance the nutritional contents, which could aid both absorption and palatability.

Modulation of cecal microbiota and fecal metabolism in mice by walnut protein.

Walnut meal is a by-product of walnut oil pressing, in which the protein content is more than 40%, which is an excellent food raw material, but at present, it is basically used as animal feed or discarded, which results in a great waste of resources, and its modulating effect on the intestinal microbiota is not clear. In this study, we used supercritically extracted walnut meal as a raw material, prepared walnut meal isolate protein (WP) by alkaline extraction and acid precipitation, and systematically analyzed its structure by Fourier infrared spectroscopy (FTIR), Raman spectroscopy (Raman), and scanning electron microscopy (SEM); meanwhile, we explored the effects of WP on the cecal bacterial flora and fecal metabolites of mice by microbiological and metabolomic techniques. The results showed that the protein content of WP prepared using alkaline extraction and acid precipitation was as high as 83.7%, in which arginine and glutamic acid were abundant, and it has the potential to be used as a raw material for weight-loss meal replacement food; FTIR and Raman analyses showed that the absorption peaks of WP's characteristic functional groups were obvious, and that the content of the α-helix and ß-fold in the secondary structure was greater than 30%, which indicated that it was structurally stable; differential scanning calorimetry (DSC) and SEM analyses showed that WP is a typical spherical particle, its denaturation temperature is 73.6 °C, and it has good thermal stability. Supplementation of WP significantly altered the composition of the intestinal flora in mice, with an increase in beneficial bacteria and a decrease in harmful bacteria; the strongest modulation of the intestinal flora was achieved by altering the composition of the intestinal flora and by increasing the number of Akkermansia (p < 0.01), which consequently affects the function of the microbiota. Based on LC-MS metabolomic results, we identified a total of 87 WP-regulated metabolites, mainly enriched in the bile secretion pathway, which had the highest relevance, followed by benzoxazine biosynthesis. In summary, walnut protein is an important plant protein and has a positive impact on intestinal health, which may provide new ideas for the development of functional foods.

Daily Cashew and Brazil Nut Consumption Modifies Intestinal Health in Overweight Women on Energy-Restricted Intervention: A Randomized Controlled Trial (Brazilian Nuts Study).

BACKGROUND: Increased intestinal permeability and dysbiosis are related to obesity. Nuts can provide nutrients and bioactive compounds that modulate gut microbiota and inflammation, enhancing the beneficial effects of weight loss. OBJECTIVES: To evaluate the effect of consuming cashew nuts (Anacardium occidentale L.) and Brazil nuts (Bertholletia excelsa H.B.K) on intestinal permeability and microbiota, fecal SCFAs and pH, inflammation, and weight loss in energy restriction condition. METHODS: In this 8-week randomized controlled trial, 40 women with overweight or obesity were assigned to energy-restricted groups (-500 kcal/d): control group (free of nuts) or Brazilian nuts group (BN: 30 g of cashew nuts and 15 g of Brazil nuts per day). Permeability was analyzed by the lactulose/mannitol test and the microbiota by sequencing the 16S gene in the V3-V4 regions. Plasma concentrations of inflammatory cytokines (TNF, IL-6, IL-10, IL-8, IL-17A) and C-reactive protein were analyzed. RESULTS: In total, 25 women completed the intervention. Both groups lost weight without statistical differences. Lactulose excretion increased only in the control group (P < 0.05). The BN consumption increased fecal propionic acid and potentially beneficial bacteria, such as Ruminococcus, Roseburia, strains NK4A214 and UCG-002 from the Ruminococcaceae family, but also Lachnospiraceae family, Bacteroides, and Lachnoclostridium, when compared to the control group. Changes in intestinal permeability were correlated to a greater reduction in body fat (kg), and IL-8, and increases in Ruminococcus abundance. CONCLUSION: Our findings demonstrate a positive impact of BN consumption within an energy-restricted context, linked to the augmentation of potentially beneficial bacteria and pathways associated with body fat reduction. Besides, BN consumption mitigated increased intestinal permeability, although its capacity to diminish permeability or enhance weight loss proved limited. This trial was registered at the Brazilian Registry of Clinical Trials as ReBEC (ID: RBR-3ntxrm).

Aspergillus population diversity and its role in aflatoxin contamination of cashew nuts from coastal Kenya.

Cashew nuts are among the main cash crops in coastal Kenya, due in large part to their high nutritional value. Unfortunately, they also make them highly susceptible to mold contamination, resulting in biodeterioration of the nutritional value and potential contamination with toxic secondary metabolites, such as aflatoxins, that cause them to be rejected for sale at the market. We determined the population diversity of the Aspergillus species and their role in aflatoxin contamination in cashew nuts in selected coastal regions of Kenya. Fifty raw cashew nut samples were collected from post-harvest storage facilities across three counties in Kenya's coastal region and examined for moisture content and the presence of Aspergillus fungi. About 63 presumptive isolates were recovered from the cashew nuts. ITS and 28S rDNA regions were sequenced. The aflD, aflM and aflR genes were amplified to identify the potentially aflatoxigenic from the Aspergillus isolates. The Aflatoxins' presence on the isolates was screened using UV and the ammonia vapour test on coconut milk agar and validated using ELISA assay. A comparison of cashew moisture content between the three counties sampled revealed a significant difference. Sixty-three isolates were recovered and identified to section based on morphological characters and their respective ITS regions were used to obtain species identifications. Three sections from the genus were represented, Flavi and Nigri, and Terrei with isolates from the section Nigri having slightly greater abundance (n = 35). The aflD, aflM and aflR genes were amplified for all isolates to assess the presence of the aflatoxin biosynthesis pathway, indicating the potential for aflatoxin production. Less than half of the Aspergillus isolates (39.68%) contained the aflatoxin pathway genes, while 22.22% isolates were aflatoxigenic, which included only the section Flavi isolates. Section Flavi isolates identification was confirmed by calmodulin gene. The presence of species from Aspergillus section Flavi and section Nigri indicate the potential for aflatoxin or ochratoxin in the cashew nuts. The study established a foundation for future investigations of the fungi and mycotoxins contaminating cashew nuts in Kenya, which necessitates developing strategies to prevent infection by mycotoxigenic fungi, especially during the storage and processing phases.

Fluorine-functionalized covalent organic framework as efficient solid phase extraction sorbent for adsorption of aflatoxins in nuts.

In this study, a new fluorine-functionalized covalent organic framework (F-COF) was designed and fabricated by the direct polycondensation of tris(4-aminophenyl)amine and 2,3,5,6-tetra-fluoroterephthaldehyde for the first time. F-COF exhibited a remarkably enhanced adsorption capability compared with that of the fluorine-free COF. The favorable adsorption of aflatoxins was attributed to multiple interactions including pseudo hydrogen bond, F-O, π-π, F-π interactions and hydrophobic interactions between F-COF and aflatoxins. By coupling F-COF based solid phase extraction with high-performance liquid chromatography equipped with fluorescence detector, a rapid and sensitive method for determining aflatoxins (aflatoxin B1, B2, G1 and G2) in nuts (peanuts and pistachios) was established. Under optimal conditions (35 mg F-COF, 100 mL sample solution, 3 mL min-1 as sample loading rate, pH<7, 0.2 mL acetonitrile as desorption solvent), the limits of detection for aflatoxins were 0.02-0.30 ng g-1. The linear range was 0.08-16.0 ng g-1 and the recoveries of the F-COF-based method were 83.5-114 % with relative standard deviations less than 8.0 %.

Integrated Metabolomics, Transcriptome and Functional Analysis Reveal Key Genes Are Involved in Tree Age-Induced Amino Acid Accumulation in Torreya grandis Nuts.

Torreya grandis is native Chinese tree species of economic significance, renowned for its long lifespan and the rich nutritional value of its nuts. In this study, we analyzed the morphological characteristics, metabolites, associated gene expressions, and regulatory mechanism in nuts from young (10 years old) and old (1000 years old) T. grandis trees. We observed that the length, width, and weight of nuts from older trees were considerably greater than those from younger trees. Metabolomic analysis revealed that the concentrations of 18 amino acids and derivatives (including histidine and serine) in nuts from older trees were markedly higher than those in nuts from younger trees. Transcriptome and metabolomic correlation analysis identified 16 genes, including TgPK (pyruvate kinase), TgGAPDH (glyceraldehyde 3-phosphate dehydrogenase), and others, which exhibit higher expression levels in older trees compared to younger trees, as confirmed by qRT-PCR. These genes are associated with the biosynthesis of histidine, glutamic acid, tryptophan, and serine. Transient expression of TgPK in tobacco led to increased pyruvate kinase activity and amino acid content (histidine, tryptophan, and serine). Additionally, dual-luciferase assays and yeast one-hybrid results demonstrated that TgWRKY21 positively regulates TgPK expression by directly binding to the TgPK promoter. These findings not only demonstrate the nutritional differences between nuts from young and old trees but also offer fresh insights into the development of nutritional sources and functional components based on nuts from old trees, enriching our understanding of the potential benefits of utilizing nuts from older trees.

Residues of Deltamethrin in Pine Needles and Pine Nuts of Catalonia (Spain).

In recent years, recurrent droughts have weakened stone pine (Pinus pinea) forests and facilitated the emergence of harmful pests and diseases, including the Leptoglossus occidentalis. The production of stone pine nuts has declined over the past five years. To control this hemipteran pest, a synthetic pyrethroid insecticide called deltamethrin is being tested. However, it is necessary to estimate the residue left by these treatments in forest stands. Therefore, a fast and robust analytical procedure was developed based on QuEChERS clean-up extraction, followed by gas chromatography coupled with an electron capture detector. This optimized method can detect residual concentrations of deltamethrin in pine nuts and pine needles up to 0.1 and 6 µg kg-1, respectively, with a limit of quantification of 0.4 and 20 µg kg-1. Great recoveries (between 84 and 102%) were obtained for both matrices, and no matrix effect was observed. The results showed that two weeks after spraying, the deltamethrin content in the needles of stone pines decreased by up to 75%, and after nine months, its presence was like that of nontreated trees.

Molecular Characterization of Local Walnut (Juglans regia) Genotypes in the North-East Parnon Mountain Region of Greece.

Walnut is one of the most important nuts regarding their production and consumption. The available but uncharacterized genetic resources of walnut are important for the development and breeding of local varieties. Greece holds an important number of genetically uncharacterized walnut landraces, especially within the area of Parnon, which is considered to play a significant role as an in situ gene bank, due to its unique location traits. However, the genetic characterization and further use of these resources has been insufficient, due to the absence of genetic studies. In this study, we implemented SSR molecular markers, both to genetically characterize the walnut tree genetic diversity of the Parnon area and to identify its unique genetic structure, which will form the starting material for subsequent breeding programs. Overall, high levels of genetic variation were found among the individual walnut accessions that were collected in the Parnon mountain region.

Water-extractable polysaccharide fraction PNE-P1 from Pinus koraiensis pine nut: Structural features and immunostimulatory activity.

The polysaccharide fraction PNE-P1 was isolated from hot water extract (PNE) of the defatted meal of pine nuts (Pinus koraiensis) using DEAE-cellulose column chromatography. This fraction had three components of molecular masses 1251, 616, and 303 g/mol consisting mainly of arabinose, xylose, and galacturonic acid at a molar ratio of 2:1.6:1. Structural analysis with FTIR/Raman, methylation and GC-MS, and NMR revealed that PNE-P1 is a cell wall polysaccharide complex including arabinan, heteroxylan, homogalacturonan (HM) and rhamnogalacturonan I (RG-I) parts. Being nontoxic to RAW 264.7 macrophages in the concentration range of 10-200 µg/mL, PNE-P1 promoted proliferation of these cells, significantly induced the secretion of proinflammatory cytokines (TNF-α and IL-6) and chemokines (RANTES and MIP-1α) and enhanced the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and nitric oxide (NO). PNE-P1 also markedly induced macrophage-mediated phagocytosis of apoptotic Jurkat T cells. These results demonstrate that pine nuts Pinus koraiensis contain a complex of water-soluble plant cell wall polysaccharides, which can stimulate innate immunity by potentiating macrophage function.

Comparative metabolomics study on areca nut from China and Southeast Asia (Thailand and Indonesia).

INTRODUCTION: Areca nut is an economic crop and an important component in traditional Chinese medicine (TCM) and ethnomedicine. The crop is rich in alkaloids and flavonoids. Most previous studies have focused on the chemical components, especially alkaloids, in crops from certain areca nut-producing areas. OBJECTIVE: The purpose of this study was to compare the differences in areca nut seeds in two main cultivation areas, identify differential metabolites, and evaluate seed quality in different production areas. METHODS: A widely targeted metabolomics method based on ultrahigh-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UHPLC-QQQ-MS), combined with the TCM systems pharmacology (TCMSP) database and multivariate statistical analysis, was used in this study to maximise the differentiation between quality characteristics of areca nut seeds from China and Southeast Asian regions. RESULTS: Altogether, 1031 metabolites were identified in areca nut seeds; by querying the TCMSP database, 375 metabolites were identified as the main active ingredients. Moreover, the research showed that the metabolic profiles of areca nut seeds from China (ASCN) and Southeast Asia (ASSA) exhibit significant differences, and the difference is mainly reflected in 318 compounds. The relative content of 146 metabolites in ASCN was significantly higher than that in ASSA. Through Kyoto Encyclopedia of Genes and Genomes (KEGG) comparative analysis, areca nut seed metabolites in Chinese production areas were determined to have a wider metabolic pathway. CONCLUSION: The areca nut seeds from cultivation areas possess many metabolites that are beneficial for health, including alkaloids, amino acids, phenolic acids, and lipids. Thus, compared with ASSA, ASCN have a higher medicinal value. This study provides a direction for the subsequent development and utilisation of areca nut seeds.

Research Progress on the Preparation and Function of Antioxidant Peptides from Walnuts.

Food-derived peptides have good antioxidant activity and are highly safe for humans; consequently, there has been continuous growth in research on antioxidants, with potential applications in food, medicine, cosmetics, and other fields. Among food-derived peptides, walnut-derived peptides have attracted increasing attention as food-derived peptides rich in eight essential amino acids. This review summarizes the progress made in the development and identification of antioxidant peptides in walnut proteins. This article mainly describes the interaction between reactive oxygen species and cellular antioxidant products, modulation of enzyme content and activity, and regulation of the redox signaling pathways and analyzes the mechanisms of reduction in oxidative stress. Finally, the complex structure-activity relationships of walnut-derived peptides are analyzed based on their amino acid composition and secondary structure of the polypeptides. This review provides a theoretical basis for the production of walnut-derived antioxidant peptides and could help promote the development of the walnut industry.

Isolation, Identification, Activity Evaluation, and Mechanism of Action of Neuroprotective Peptides from Walnuts: A Review.

As human life expectancy increases, the incidence of neurodegenerative diseases in older adults has increased in parallel. Walnuts contain bioactive peptides with demonstrated neuroprotective effects, making them a valuable addition to the diet. We here present a comprehensive review of the various methods used to prepare, isolate, purify, and identify the neuroprotective peptides found in walnuts. We further summarise the different approaches currently used to evaluate the activity of these peptides in experimental settings, highlighting their potential to reduce oxidative stress, neuroinflammation, and promote autophagy, as well as to regulate the gut microflora and balance the cholinergic system. Finally, we offer suggestions for future research concerning bioavailability and improving or masking the bitter taste and sensory properties of final products containing the identified walnut neuroprotective peptides to ensure successful adoption of these peptides as functional food ingredients for neurohealth promotion.

Walnut Protein: A Rising Source of High-Quality Protein and Its Updated Comprehensive Review.

Recently, plant protein as a necessary nutrient source for human beings, a common ingredient of traditional processed food, and an important element of new functional food has gained prominence due to the increasing demand for healthy food. Walnut protein (WP) is obtained from walnut kernels and walnut oil-pressing waste and has better nutritional, functional, and essential amino acids in comparison with other vegetable and grain proteins. WP can be conveniently obtained by various extraction techniques, including alkali-soluble acid precipitation, salting-out, and ultrasonic-assisted extraction, among others. The functional properties of WP can be modified for desired purposes by using some novel methods, including free radical oxidation, enzymatic modification, high hydrostatic pressure, etc. Moreover, walnut peptides play an important biological role both in vitro and in vivo. The main activities of the walnut peptides are antihypertensive, antioxidant, learning improvement, and anticancer, among others. Furthermore, WP could be applied in the development of functional foods or dietary supplements, such as delivery systems and food additives, among others. This review summarizes recent knowledge on the nutritional, functional, and bioactive peptide aspects of WP and possible future products, providing a theoretical reference for the utilization and development of oil crop waste.