Prediction of Walnut Deterioration Using Kernel Oxidative Stability.
Monitoring walnut oxidation is essential to control walnut quality during storage. An accelerated oxidation method for differentiating the oxidative stability index (OSI) of walnut kernels was examined and the effects of instrument operational parameters such as temperature and airflow were evaluated. Four cultivars, Chandler, Solano, Durham, and Howard were analyzed at 110, 120, and 130 °C with 15, 20, and 25 L h-1 airflow. Analysis using 110 °C with 25 L h-1 yielded the lowest coefficients of variance (4.4) than other operational parameters; analysis using the same temperature at lower airflow, 15 L h-1, yield the highest coefficient of variance (10.5). Kernel OSI values were independent of airflow, however, dependence of temperature coefficient and Q10 were demonstrated. The results from selected parameters were correlated with fat and moisture content, peroxide value, UV absorbances, oil oxidative stability, hexanal, and rancidity to establish the relationships between OSI values and quality changes during storage. Using 0.5 g of ground kernels, at 110 °C with 25 L h-1 airflow gave a lower coefficient of variance and higher correlation with kernel quality and oxidative markers comparing to other combinations of operating parameters.
Effect of storage temperatures, packaging materials and storage periods on antioxidant activity and non-enzymatic browning of antioxidant treated walnut kernels.
The effect of antioxidants, temperature, packaging materials and storage periods was investigated in medium shelled walnut kernels (Hamdan) variety. The kernels were mechanically dried (40 °C), standardized and treated with butylated hydroxylanisole and butylated hydroxytoluene in combination at concentrations (0.015%) each. Then packed in laminates under vacuum and high density polyethylene non vacuum packaging materials and stored under ambient and refrigerated temperature conditions (4 °C) for a period of 9 months. All tested extracts possessed appreciable antioxidant potential. The bioactive compounds were identified by using chromatographic techniques (GC-MS and LC-MS). Before storage dried kernels exhibited high values of total phenols (31.23 mgGAE/gm), DPPH (215.13 µmol TAEg-1) and low value of non enzymatic browning (0.63 OD). Walnuts packed in laminates under vacuum and refrigerated conditions exhibited higher values of total phenols, total flavonoids, DPPH and subsequently lower change in non-enzymatic browning reactions throughout the experiment. After 90 days of storage maximum loss in total phenols and DPPH value and highest value of non enzymatic browning was observed in high density polyethylene non vacuum packaging materials under ambient temperature. The major phenolic components identified by GC/MS and LC/MS analysis were linoleic acid, oleic acid, hexadecanoic acid, epicatechin, quercetin, epicatechin and ellagic acid respectively. This study validates the antioxidant potential of the walnut kernels and the positive relationship between total phenolic content, total flavonoids and antioxidant activity.
Biocontrol potential of native yeast strains against Aspergillus flavus and aflatoxin production in pistachio.
Aspergillus flavus is the main aflatoxin producer in food and feed and has wide ecological niches. Contamination of food products such as pistachio nuts and aflatoxin secretion directly affects food safety and international food product trades. Abilities of 13 yeast strains isolated from 200 soil and pistachio nut samples collected in Iranian orchards to reduce the growth of A. flavus as well as aflatoxin production were assessed in dual culture, volatile and non-volatile compounds tests. The growth of A. flavus was reduced by 32-60%, 13-31% and 40-61% in dual culture, volatile and non-volatile compounds, respectively, while aflatoxin B1 production was diminished by 90.6-98.3%. Based on these assays, five yeast strains were selected for co-inoculation experiments using soil, pistachio hulls and leaf. A significant reduction in colony-forming units (CFU) ranging from 23% to 110% (p < .05) was observed. Molecular, physiological and morphological identification revealed these were strains of Pichia kudriavzevii and Lachansea thermotolerans. Aflatoxin biocontrol with yeast strains possesses many advantages including the ease of commercial production and organic application which is an environmental approach. More investigation is required to understand the efficiency of selective strains to inhibit A. flavus and aflatoxin production as well as withstand predominant abiotic stress in pistachio orchards and mass production in field application.
Fate of aflatoxins during almond oil processing.
Almonds rejected as inedible are often used for production of almond oil. However, low-quality almonds are frequently contaminated with aflatoxins, and little is known regarding transfer of aflatoxins to almond oil during processing. In this study, oil was produced from reject almonds by hexane extraction. Of 19 almond samples that were naturally contaminated with aflatoxins, 17 oil samples contained measurable amounts of aflatoxins, and aflatoxin content of contaminated oil was correlated with aflatoxin content of the nuts. However, oil aflatoxin levels were not correlated with the oxidation level of the oil as measured by percent free fatty acids and peroxide value. Adsorbents used in oil refining were tested for their ability to remove aflatoxins from contaminated oil. Fuller's earth and bentonite were the most effective, removing 96% and 86% of total aflatoxins from contaminated oil samples, respectively. Treatment with diatomaceous earth, in contrast, had no effect on aflatoxin levels in oil. These results show that oil refining steps using mineral clay adsorbents may also function to remove aflatoxins from contaminated oil.
Physiochemical And Microstructural Properties And Probiotic Survivability Of Symbiotic Almond Yogurt Using Polymerized Whey Protein As A Co-Gelation Agent.
A plain symbiotic almond yogurt-like product was formulated and developed using a plant-based starter YF-L02 (Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus supplemented with Lactobacillus acidophilus, Lactobacillus paracasei, and Bifidobacterium animalis) and inulin; 0.6% polymerized whey protein (PWP), 0.3% pectin, and 0.05% xanthan gum were optimized for the formula of the almond yogurt alternative. Two groups with/without calcium citrate and vitamin D2 were prepared and analyzed for chemical composition, changes in pH, viscosity, and probiotic survivability during storage at 4 °C for 10 weeks. The results showed that (1) over 10 weeks storage, the differences in the pH, viscosity, and probiotic survivability between the control and the fortified samples were not significant (P > 0.05); (2) the pH of both yogurt samples decreased 0.2 units while their viscosity slightly increased during storage; (3) the populations of L. paracasei and B. animalis remained above 106 cfu/g during the storage, whereas the population of L. acidophilus decreased dramatically during the first 4 weeks, especially the control group; (4) the microstructure was examined by scanning electron microscopy, revealing a compact and denser gel structure formed by 0.6% PWP with the presence of 0.3% pectin and 0.05% xanthan gum. In conclusion, PWP might be a proper gelation agent for the formulation of symbiotic almond yogurt alternative. PRACTICAL APPLICATION: In this study, polymerized whey protein was used as a gelation agent to formulate symbiotic almond yogurt alternatives with comparable physical texture and probiotic survivability to dairy yogurt during storage. This technology may be used for the development of plant-based fermented foods.
Walnut Allergy across Europe: Distribution of Allergen Sensitization Patterns and Prediction of Severity.
Background: Walnut allergy is common across the globe, but data on the involvement of individual walnut components is scarce. Objectives: To identify geographical differences in walnut component sensitization across Europe, explore co-sensitization and cross-reactivity, and assess associations of clinical and serological determinants with severity of walnut allergy. Methods: As part of the EuroPrevall outpatient surveys in 12 European cities, standardized clinical evaluation was conducted in 531 individuals reporting symptoms to walnut, with sensitization to all known walnut components assessed in 202 subjects. Multivariable Lasso regression was applied to investigate predictors for walnut allergy severity. Results: Birch-pollen related walnut sensitization (Jug r 5) dominated in Northern and Central Europe; LTP sensitization (Jug r 3) in Southern Europe. Profilin sensitization (Jug r 7) was prominent throughout Europe. Sensitization to storage proteins (Jug r 1, 2, 4 and 6) was detected in up to 10% of subjects. The walnut components that showed strong correlations with pollen and other foods differed between centres. The combination of determinants best predicting walnut allergy severity were: symptoms upon skin contact with walnut, atopic dermatitis (ever), family history of atopic disease, mugwort pollen allergy, sensitization to cat/dog, positive SPT to walnut, and IgE to Jug r 1, 5, 7 or carbohydrate determinants (AUC = 0.81 [95%-CI 0.73-0.89]). Conclusions: Walnut allergic subjects across Europe show clear geographical differences in walnut component sensitization and co-sensitization patterns. A predictive model combining results from component-based serology testing with results from extract-based testing and information on clinical background, allows for good discrimination between mild-to-moderate and severe walnut allergy.
Efficacy and safety of oral immunotherapy with AR101 in European children with a peanut allergy (ARTEMIS): a multicentre, double-blind, randomised, placebo-controlled phase 3 trial.
Background: Peanut allergy is the leading cause of food-related anaphylaxis. Current management options can negatively affect food allergy-related quality of life. We aimed to investigate the efficacy of an investigational oral biologic drug (AR101). Methods: The AR101 Trial in Europe Measuring Oral Immunotherapy Success in peanut-allergic children (ARTEMIS) trial was a multicentre, double-blind, randomised, placebo-controlled phase 3 trial done at 18 hospitals in Ireland, France, Germany, Italy, Spain, Sweden, and the UK. Children and adolescents with peanut allergy, aged 4-17 years, who developed dose-limiting symptoms to 300 mg or less peanut protein (equivalent to approximately one peanut kernel) during a double-blind placebo-controlled food challenge test at study entry were enrolled. Participants were randomly assigned (3:1) to receive daily doses of either AR101 oral immunotherapy (AR101 group) or a taste-masked placebo (placebo group). All participants, investigators, and care providers were masked to treatment allocation until the study was completed. Doses were increased every 2 weeks over 6 months until a dose of 300 mg was reached and maintained for 3 months. The primary endpoint was the proportion of participants in the intention-to-treat or safety population (defined as those participants who had been randomly assigned and had received at least one dose of the assigned drug) who could consume a single dose of 1000 mg (cumulative dose 2043 mg) peanut protein without developing dose-limiting allergic symptoms at an exit double-blind placebo-controlled food challenge after 9 months of treatment. Additional endpoints included safety (ie, the frequency and severity of adverse events) and changes in food allergy-related quality of life, assessed by use of age-appropriate Food Allergy Quality of Life Questionnaires (FAQLQs) and the Food Allergy Independent Measure (FAIM). The study is registered with ClinicalTrials.gov, NCT03201003, and is completed. Findings: Between June 12, 2017, and Feb 15, 2018, 227 patients were screened, of whom 175 were randomly assigned to the AR101 group (n=132) and the placebo group (n=43). All primary and secondary endpoints were met. 77 (58%) of 132 participants in the AR101 group tolerated 1000 mg peanut protein at the exit food challenge versus one (2%) of 43 participants in the placebo group (AR101-placebo treatment difference 56·0% [95% CI 44·1-65·2], p<0·0001). Adverse events were reported by almost all participants. The maximum severity of adverse events reported was mild or moderate for most participants who received AR101 (mild, 66 [50%] of 132 participants; moderate, 63 [48%]; and severe, one [1%]) or placebo (mild, 24 [56%] of 43 participants; moderate, 18 [42%]; severe, none). Participants aged 8-12 years in the AR101 group reported improvements that exceeded the minimum clinically important difference between the two groups across all FAQLQ domains. Additionally, participants in the AR101 group and their caregivers reported improvements that exceeded the minimum clinically important difference in FAIM domains related to the perceived likelihood and outcomes of a severe allergic reaction. Interpretation: AR101 oral immunotherapy treatment led to rapid desensitisation to peanut protein, with a predictable safety profile that improved with treatment, and an associated improvement in self-reported and caregiver-reported food allergy-related quality of life. These patient-oriented outcomes provide invaluable data to help physicians, patients, and caregivers make informed, shared decisions on the management of peanut allergy. Funding: Aimmune Therapeutics.
Phage Displayed Domain Antibodies (dAb) for Detection of Allergenic Pistachio Proteins in Foods.
Pistachio nuts (Pistacia vera) have been consumed by past and present-day civilizations because of their organoleptic characteristics and potential health benefits. However, they can also produce moderate to severe IgE-mediated reactions in allergic individuals. In this work, we report the isolation of the first recombinant antibodies against pistachio nut, produced without animal immunization, to be used in immunoassays for detection of allergenic pistachio in food products. Several phage display biopanning strategies were evaluated to screen the human-based domain antibody library (dAb) in search for pistachio-specific probes. The clone producing the PVF4 phage-dAb was finally selected, and it does not cross-react with cashew despite the phylogenetic proximity with pistachio. Western blot and matrix-assisted laser desorption/ionization tandem mass spectrometry (MALDI-TOF/TOF) analysis demonstrated that this clone recognised a unique band of ∼22 kDa related to the basic subunit of pistachio 11S globulin (allergen Pis v 2). The PVF4 phage-dAb allowed detection of pistachio in a food matrix with a limit of detection (LOD) of 3983 mg kg-1 in an indirect phage-enzyme-linked immunosorbent assay (ELISA). The ELISA method developed was used to assess applicability of the PVF4 phage-dAb for analysis of 77 commercial food products.
Walnut intake may increase circulating adiponectin and leptin levels but does not improve glycemic biomarkers: A systematic review and meta-analysis of randomized clinical trials.
Background & objective: Walnut intake is considered a healthy dietary approach worldwide, particularly as a nutritional tool for the management of obesity and cardiometabolic disorders. Among these lines, leptin and adiponectin, as well as glycemic biomarkers, deserve further attention. We aimed to examine the impact of walnut intake on circulation levels of leptin and adiponectin through a systematic review and meta-analysis of randomized clinical trials (RCTs); secondarily, assessing the glycemic profile as well. Methods: The literature search was implemented in four following databases: Web of Science, Scopus, PubMed/Medline, and Google Scholar, thus, determining studies that measured the effects of walnut consumption on adiponectin, leptin, and glycemic biomarkers levels from 2004 up to December 2019. Results: Fourteen trials were include in the meta-analysis, with an intervention period ranging from 5 weeks to 12 months. Walnut intake increased leptin (weighted mean difference (WMD): 2.502 ng/mL; 95 % CI: 2.147-2.856, p < 0.001) and adiponectin (WMD: 0.440 ng/mL; 95 % CI: 0.323 to 0.557, p < 0.001) levels. Pertaining to glycemic biomarkers, neither overall analyses nor sub-analyses corroborated with changes in fasting blood glucose (WMD: 0.500 mg/dL, 95 % CI: -0.596, 1.596, p = 0.371), insulin (WMD: -0.21 mg/dL, 95 % CI: -0.67, 0.24, p = 0.367), and glycated hemoglobin (WMD: 0.004 mg/dL, 95 % CI: -0.041, 0.049, p = 0.870) concentrations.
One-year dietary supplementation with walnuts modifies exosomal miRNA in elderly subjects.
Purpose: Epidemiological studies and clinical trials support the association of nut consumption with a lower risk of prevalent non-communicable diseases, particularly cardiovascular disease. However, the molecular mechanisms underlying nut benefits remain to be fully described. MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression and play a pivotal role in health and disease. Exosomes are extracellular vesicles released from cells and mediate intercellular communication. Whether nut consumption modulates circulating miRNAs (c-miRNAs) transported in exosomes is poorly described. Methods: Cognitively healthy elderly subjects were randomized to either control (n = 110, abstaining from walnuts) or daily supplementation with walnuts (15% of their total energy, ≈30-60 g/day, n = 101) for 1-year. C-miRNAs were screened in exosomes isolated from 10 samples, before and after supplementation, and identified c-miRNA candidates were validated in the whole cohort. In addition, nanoparticle tracking analysis and lipidomics were assessed in pooled exosomes from the whole cohort. Results: Exosomal hsa-miR-32-5p and hsa-miR-29b-3p were consistently induced by walnut consumption. No major changes in exosomal lipids, nanoparticle concentration or size were found. Conclusion: Our results provide novel evidence that certain c-miRNAs transported in exosomes are modulated by walnut consumption. The extent to which this finding contributes to the benefits of walnuts deserves further research.