Identification and characterization of a new pecan [Carya illinoinensis (Wangenh.)
The 7S vicilin and 11S legumin seed storage globulins belong to the cupin protein superfamily and are major food allergens in many foods from the "big eight" food allergen groups. Here, for the first time, pecan vicilin was found to be a food allergen. Western blot experiments revealed that 30% of 27 sera used in this study and 24% of the sera from 25 patients with double-blind, placebo controlled clinical pecan allergy contained IgE antibodies specific to pecan vicilin. This allergen consists a low-complexity region at its N-terminal and a structured domain at the C-terminal that contains two cupin motifs and forms homotrimers. The crystal structure of recombinant pecan vicilin was determined. The refined structure gave R/Rfree values of 0.218/0.262 for all data to 2.65 Å. There were two trimeric biological units in the crystallographic asymmetric unit. Pecan vicilin is also a copper protein. These data may facilitate the understanding of the nutritional value and the allergenicity relevance of the copper binding property of seed storage proteins in tree nuts.
Ana o 1 and Ana o 2 cashew allergens share cross-reactive CD4+ T-cell epitopes with other tree nuts.
BACKGROUND: Allergies to cashew are increasing in prevalence, with clinical symptoms ranging from oral pruritus to fatal anaphylactic reaction. Yet, cashew-specific T-cell epitopes and T-cell cross-reactivity amongst cashew and other tree nut allergens in humans remain uncharacterized. OBJECTIVES: In this study, we characterized cashew specific T-cell responses in cashew allergic subjects and examined cross-reactivity of these cashew specific cells toward other tree nut allergens. METHODS: CD154 up-regulation assay was used to determine immunodominance hierarchy among cashew major allergens at the T cell level. The phenotype, magnitude and functionality of cashew-specific T-cells was determined by utilizing ex vivo staining with MHC class II tetramers. Dual tetramer staining and proliferation experiments were used to determine cross-reactivity to other tree nuts. RESULTS: CD4+ T-cell responses were directed towards cashew allergens Ana o 1 and Ana o 2. Multiple Ana o 1 and Ana o 2 T-cell epitopes were then identified. These epitopes elicited either TH 2 or TH 2/TH 17 responses in allergic subjects, which were either cashew unique epitope or cross-reactive epitopes. For clones that recognized the cross-reactive epitope, T-cell clones responded robustly to cashew, hazelnut and/or pistachio but not to walnut. CONCLUSIONS: Phylogenetically diverse tree nut allergens can activate cashew reactive T-cells and elicit a TH 2 type response at an epitope specific level.
A Comparison of Flavor Differences between Pecan Cultivars in Raw and Roasted Forms.
The objective of this research was to explore sensory differences among 8 different pecan cultivars ("Pawnee," "Witte," "Kanza," "Major," "Lakota," "Giles," "Maramec," "Chetopa") in raw and roasted forms. The cultivars were collected from 2 growing seasons (2013 and 2014) and evaluated separately. Trained panelists evaluated each cultivar from each season in raw and roasted forms, measuring intensities of 20 flavor attributes using descriptive analysis. The intensities of 10 of the 20 flavor attributes were higher for the roasted pecans across all cultivars. These included pecan ID, overall nutty, nutty-woody, nutty-grainlike, nutty-buttery, brown, caramelized, roasted, overall sweet, and sweet. The cultivars exhibited significant differences from one another for 8 attributes: pecan ID, nutty-buttery, caramelized, acrid, woody, oily, astringent, and bitter. Each of the cultivars displayed unique flavor profiles with some demonstrating extremes of certain attributes, for example the high astringency of "Lakota" or the buttery characteristics of "Pawnee." These results may help pecan growers and pecan product manufacturers understand flavor differences between different varieties of pecans, both in raw and roasted states, and the changes that occur during this process.
Modeling the survival kinetics of Salmonella in tree nuts for use in risk assessment.
Salmonella has been shown to survive in tree nuts over long periods of time. This survival capacity and its variability are key elements for risk assessment of Salmonella in tree nuts. The aim of this study was to develop a mathematical model to predict survival of Salmonella in tree nuts at ambient storage temperatures that considers variability and uncertainty separately and can easily be incorporated into a risk assessment model. Data on Salmonella survival on raw almonds, pecans, pistachios and walnuts were collected from the peer reviewed literature. The Weibull model was chosen as the baseline model and various fixed effect and mixed effect models were fit to the data. The best model identified through statistical analysis testing was then used to develop a hierarchical Bayesian model. Salmonella in tree nuts showed slow declines at temperatures ranging from 21°C to 24°C. A high degree of variability in survival was observed across tree nut studies reported in the literature. Statistical analysis results indicated that the best applicable model was a mixed effect model that included a fixed and random variation of δ per tree nut (which is the time it takes for the first log10 reduction) and a fixed variation of ρ per tree nut (parameter which defines the shape of the curve). Higher estimated survival rates (δ) were obtained for Salmonella on pistachios, followed in decreasing order by pecans, almonds and walnuts. The posterior distributions obtained from Bayesian inference were used to estimate the variability in the log10 decrease levels in survival for each tree nut, and the uncertainty of these estimates. These modeled uncertainty and variability distributions of the estimates can be used to obtain a complete exposure assessment of Salmonella in tree nuts when including time-temperature parameters for storage and consumption data. The statistical approach presented in this study may be applied to any studies that aim to develop predictive models to be implemented in a probabilistic exposure assessment or a quantitative microbial risk assessment.
The extraction of different proteins in selenium enriched peanuts and their antioxidant properties.
In this study, the selenium enriched peanuts and the different solubility proteins extracted from them were investigated. The dried defatted selenium enriched peanuts (SeP) powder (0.3147 μg/g) had a 2.5-fold higher mean total selenium concentration than general peanuts (GP) power (0.1233 μg/g). The SeP had higher concentration of selenium, manganese and zinc than that of GP, but less calcium. The rate of extraction of protein was 23.39% for peanuts and alkali soluble protein was the main component of protein in SeP, which accounted for 92.82% of total soluble protein and combined selenium was 77.33% of total selenium protein. In different forms of proteins from SeP, the WSePr due to higher concentration of selenium had higher DPPH free-radical scavenging activity, higher reducing activity and longer induction time than other proteins.
Development of a Drinkable, Peanut-Based Dietary Supplement and Comparison of Its Nutritional and Microbiological Qualities with Commercial Products.
This study was undertaken to formulate, using peanuts as a major ingredient, a beverage which will benefit older adults who are at a high risk of protein-energy malnutrition and other health complications, and to compare its nutritional and microbiological qualities to commercial products. Peanuts, rice flour, and flaxseed meal in a ratio of 48.0:49.8:2.2 were mixed with water (20% solids) and cooked into gruel which was sequentially treated with BAN® , (480 KNU-B/g, 75 °C 1 h), Alcalase® (2.4 AU-A/g, 60 °C 1 h), and Flavourzyme® (1000 LAPU/g, 55 °C 1 h) to predigest starch and protein, respectively. The degree of hydrolysis and product viscosity during hydrolysis was measured. The nutritional and microbiological qualities of the product were compared to 10 commercial products. Results indicate that 60% of starch was hydrolyzed while a total of 1.62% protein hydrolysis was observed. Product viscosity reduced from 228.55 to 3.60 cP at the end of hydrolysis. The formulation had no cholesterol and low sodium which was a functional property that was absent in the commercial products. Results of this study suggest that the formulation can be further optimized into a unique product that could cater for the protein needs and other nutritional requirements of older adults.
Use of Cold Atmospheric Plasma to Detoxify Hazelnuts from Aflatoxins.
Aflatoxins, produced by Aspergillus flavus and A. parasiticus, can contaminate different foodstuffs, such as nuts. Cold atmospheric pressure plasma has the potential to be used for mycotoxin detoxification. In this study, the operating parameters of cold atmospheric pressure plasma were optimized to reduce the presence of aflatoxins on dehulled hazelnuts. First, the effect of different gases was tested (N₂, 0.1% O₂ and 1% O₂, 21% O₂), then power (400, 700, 1000, 1150 W) and exposure time (1, 2, 4, and 12 min) were optimized. In preliminary tests on aflatoxin standard solutions, this method allowed to obtain a complete detoxification using a high power for a few minutes. On hazelnuts, in similar conditions (1000 W, 12 min), a reduction in the concentration of total aflatoxins and AFB₁ of over 70% was obtained. Aflatoxins B₁ and G₁ were more sensitive to plasma treatments compared to aflatoxins B₂ and G₂, respectively. Under plasma treatment, aflatoxin B₁ was more sensitive compared to aflatoxin G₁. At the highest power, and for the longest time, the maximum temperature increment was 28.9 °C. Cold atmospheric plasma has the potential to be a promising method for aflatoxin detoxification on food, because it is effective and it could help to maintain the organoleptic characteristics.
Effects of heat and high-pressure treatments on the solubility and immunoreactivity of almond proteins.
The effects of dry and moist heat, autoclave sterilization and high-pressure treatment on the biochemical characteristics and immunological properties of almond proteins were investigated. Changes in the solubility and immunoreactivity of almond proteins extracted from treated almond flour were evaluated using a total protein assay, indirect competitive inhibition enzyme-linked immunosorbent assay (IC-ELISA), and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Almond proteins were stable during dry-heat treatment at temperatures below 250°C. Dry heat at 400°C, boiling, autoclave sterilization and high-pressure treatment in the presence of water at ⩾500MPa greatly reduced the solubility and immunoreactivity of almond proteins. SDS-PAGE revealed that the protein profiles of almond flour samples treated under these conditions also changed significantly. The synergistic effects of heat, pressure and the presence of water contributed to significant changes in solubility and immunoreactivity of almond proteins.
Multicentre Double-Blind Placebo-Controlled Food Challenge Study in Children Sensitised to Cashew Nut.
BACKGROUND: Few studies with a limited number of patients have provided indications that cashew-allergic patients may experience severe allergic reactions to minimal amounts of cashew nut. The objectives of this multicentre study were to assess the clinical relevance of cashew nut sensitisation, to study the clinical reaction patterns in double-blind placebo-controlled food challenge tests and to establish the amount of cashew nuts that can elicit an allergic reaction. METHODS AND FINDINGS: A total of 179 children were included (median age 9.0 years; range 2-17 years) with cashew nut sensitisation and a clinical history of reactions to cashew nuts or unknown exposure. Sensitised children who could tolerate cashew nuts were excluded. The study included three clinical visits and a telephone consultation. During the first visit, the medical history was evaluated, physical examinations were conducted, blood samples were drawn and skin prick tests were performed. The children underwent a double-blind placebo-controlled food challenge test with cashew nut during the second and third visits. The study showed that 137 (76.5%) of the sensitised children suspected of allergy to cashew nut had a positive double-blind placebo-controlled food challenge test, with 46% (63) manifesting subjective symptoms to the lowest dose of 1 mg cashew nut protein and 11% (15) developing objective symptoms to the lowest dose. Children most frequently had gastro-intestinal symptoms, followed by oral allergy and skin symptoms. A total of 36% (49/137) of the children experienced an anaphylactic reaction and 6% (8/137) of the children were treated with epinephrine. CONCLUSION: This prospective study demonstrated a strikingly high percentage of clinical reactions to cashew nut in this third line population. Severe allergic reactions, including anaphylaxis requiring epinephrine, were observed. These reactions were to minimal amounts of cashew nut, demonstrated the high potency of this allergens.
Peanut allergy in Mexican children: what is the effect of age at first consumption?
Studies suggest that children who start solid foods early are at risk for developing food allergies. Herein, we evaluated the effects of the introduction of peanuts to the diets of children on emerging peanut allergies. Children with allergic rhinitis and asthma were enrolled in the present study and evaluated in four stages. In the first stage, a clinical history was completed for all participants. In the second stage, skin tests were conducted to detect the sensitization to peanuts. In the third stage, the parents were interviewed about the peanut-eating habits of their children. In the fourth stage, children with a convincing history of allergy or a positive peanut skin test result were subjected to an open oral food challenge (OOFC). Three hundred children in four groups were included, 58.2% of the subjects were male, and the mean age was 7.3±3.9 years. The median age of first exposure to peanuts in patients with peanut allergies was greater than that in children without peanut allergies (2 years versus 1 year; p=0.009). The multivariate analysis, including only those children subjected to the OOFC, revealed that the consumption of peanuts after the age of ≥2 years is a risk factor for developing a peanut allergy (odds ratio=8.0, 95% confidence interval 1.3-50.0, p=0.026). The results of the present study showed that the late introduction of peanuts to children increases the risk of developing a peanut allergy.