Allergenicity reduction of the bio-elicited peanut sprout powder (BPSP) and toxicological acceptance of BPSP-supplemented diets assessed with ICR mice.

The allergenic and toxicological acceptances of the bio-elicited peanut sprout powder (BPSP) have not been assessed. BPSP was generated from peanut kernels germinated at 26-28 °C for 72 h (designated as 72 h-NGS). The 72 h-NGS were subsequently sliced, incubated, dried, defatted and pulverized to generate bio-elicited peanut sprout powder (BPSP). Protein solubility of BPSP increased 2.6-fold compared to 72 h-NGS. SDS-PAGE analysis revealed BPSP production triggered extensive degradation of the high-molecular weight peanut allergic proteins, mainly Ara h 1 and Ara h 3. Western blotting detected with peanut allergic patients' IgE indicated decreased in vitro reactivity. Food safety assessment of BPSP was performed with ICR mice fed with basal (control) and three doses of formulated BPSP-supplemented diets containing 0.11 g (normal), 2.5 g (high) and 25 g (super high) BPSP /kg BW. Animals appeared healthy with steady body weight gain in all groups during the entire 35-day dietary intervention. Hematological and serum biochemical analyses revealed no significant difference among groups. Histopathological examination on the tissue sections of primary organs further supported safety with no pathologies. The in vitro allergic reduction and toxicological safety in the BPSP-supplemented dietary intervention in the ICR mice study, support moving forward with BPSP-involved product development. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-022-05537-7.

Allergenic properties of enzymatically hydrolyzed peanut flour extracts.

BACKGROUND: Peanut flour is a high-protein, low-oil, powdered material prepared from roasted peanut seed. In addition to being a well-established food ingredient, peanut flour is also the active ingredient in peanut oral immunotherapy trials. Enzymatic hydrolysis was evaluated as a processing strategy to generate hydrolysates from peanut flour with reduced allergenicity. METHODS: Soluble fractions of 10% (w/v) light roasted peanut flour dispersions were hydrolyzed with the following proteases: Alcalase (pH 8.0, 60°C), pepsin (pH 2.0, 37°C) or Flavourzyme (pH 7.0, 50°C) for 60 min. Western blotting, inhibition ELISA and basophil activation tests were used to examine IgE reactivity. RESULTS: Western blotting experiments revealed the hydrolysates retained IgE binding reactivity and these IgE-reactive peptides were primarily Ara h 2 fragments regardless of the protease tested. Inhibition ELISA assays demonstrated that each of the hydrolysates had decreased capacity to bind peanut-specific IgE compared with nonhydrolyzed controls. Basophil activation tests revealed that all hydrolysates were comparable (p > 0.05) to nonhydrolyzed controls in IgE cross-linking capacity. CONCLUSIONS: These results indicate that hydrolysis of peanut flour reduced IgE binding capacity; however, IgE cross-linking capacity during hydrolysis was retained, thus suggesting such hydrolysates are not hypoallergenic.

The effects of different dry roast parameters on peanut quality using an industrial belt-type roaster simulator.

Peanuts roasted to equivalent surface colors at different temperature/time combinations can vary substantially in chemical and physical properties related to product quality. This study used a pilot plant scale roaster that simulates the configurations of one of the most common industrial roaster, a multi-zone belt roaster. Jumbo-size runner-type peanuts were systematically roasted at 5 temperatures (149-204°C) to three Hunter l-values of 53, 48.5, and 43, corresponding to light, medium, and dark roasts. Moisture and tocopherol contents were more closely correlated with roast color rather than temperature, with exceptions at 149°C. Moisture decreased with darker roast color, while the total tocopherols were greatest in peanut oils with darker colors. Yield stress of peanut pastes increased as the color darkened, indicating spreadability correspondingly decreased with darker roast colors. The overall flavor of roasted peanuts was found to be optimized at 177°C/15min with the medium roast color.

Stability and immunogenicity of hypoallergenic peanut protein-polyphenol complexes during in vitro pepsin digestion.

Allergenic peanut proteins are relatively resistant to digestion, and if digested, metabolized peptides tend to remain large and immunoreactive, triggering allergic reactions in sensitive individuals. In this study, the stability of hypoallergenic peanut protein-polyphenol complexes was evaluated during simulated in vitro gastric digestion. When digested with pepsin, the basic subunit of the peanut allergen Ara h 3 was more rapidly hydrolyzed in peanut protein-cranberry or green tea polyphenol complexes compared to uncomplexed peanut flour. Ara h 2 was also hydrolyzed more quickly in the peanut protein-cranberry polyphenol complex than in uncomplexed peanut flour. Peptides from peanut protein-cranberry polyphenol complexes and peanut protein-green tea polyphenol complexes were substantially less immunoreactive (based on their capacity to bind to peanut-specific IgE from patient plasma) compared to peptides from uncomplexed peanut flour. These results suggest that peanut protein-polyphenol complexes may be less immunoreactive passing through the digestive tract in vivo, contributing to their attenuated allergenicity.

Strategies to mitigate peanut allergy: production, processing, utilization, and immunotherapy considerations.

Peanut (Arachis hypogaea L.) is an important crop grown worldwide for food and edible oil. The surge of peanut allergy in the past 25 years has profoundly impacted both affected individuals and the peanut and related food industries. In response, several strategies to mitigate peanut allergy have emerged to reduce/eliminate the allergenicity of peanuts or to better treat peanut-allergic individuals. In this review, we give an overview of peanut allergy, with a focus on peanut proteins, including the impact of thermal processing on peanut protein structure and detection in food matrices. We discuss several strategies currently being investigated to mitigate peanut allergy, including genetic engineering, novel processing strategies, and immunotherapy in terms of mechanisms, recent research, and limitations. All strategies are discussed with considerations for both peanut-allergic individuals and the numerous industries/government agencies involved throughout peanut production and utilization.

Novel strategy to create hypoallergenic peanut protein-polyphenol edible matrices for oral immunotherapy.

Peanut allergy is an IgE-mediated hypersensitivity. Upon peanut consumption by an allergic individual, epitopes on peanut proteins bind and cross-link peanut-specific IgE on mast cell and basophil surfaces triggering the cells to release inflammatory mediators responsible for allergic reactions. Polyphenolic phytochemicals have high affinity to bind proteins and form soluble and insoluble complexes with unique functionality. This study investigated the allergenicity of polyphenol-fortified peanut matrices prepared by complexing various polyphenol-rich plant juices and extracts with peanut flour. Polyphenol-fortified peanut matrices reduced IgE binding to one or more peanut allergens (Ara h 1, Ara h 2, Ara h 3, and Ara h 6). Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) suggested changes in secondary protein structure. Peanut protein-cranberry polyphenol fortified matrices triggered significantly less basophil degranulation than unmodified flour in an ex vivo assay using human blood and less mast cell degranulation when used to orally challenge peanut-allergic mice. Polyphenol fortification of peanut flour resulted in a hypoallergenic matrix with reduced IgE binding and degranulation capacity, likely due to changes in protein secondary structure or masking of epitopes, suggesting potential applications for oral immunotherapy.

Comparative proteomic analysis and IgE binding properties of peanut seed and testa (skin).

To investigate the protein composition and potential allergenicity of peanut testae or skins, proteome analysis was conducted using nanoLC-MS/MS sequencing. Initial amino acid analysis suggested differences in protein compositions between the blanched seed (skins removed) and skin. Phenolic compounds hindered analysis of proteins in skins when the conventional extraction method was used; therefore, phenol extraction of proteins was necessary. A total of 123 proteins were identified in blanched seed and skins, and 83 of the proteins were common between the two structures. The skins contained all of the known peanut allergens in addition to 38 proteins not identified in the seed. Multiple defense proteins with antifungal activity were identified in the skins. Western blotting using sera from peanut-allergic patients revealed that proteins extracted from both the blanched seed and skin bound significant levels of IgE. However, when phenolic compounds were present in the skin protein extract, no IgE binding was observed. These findings indicate that peanut skins contain potentially allergenic proteins; however, the presence of phenolic compounds may attenuate this effect.

KI-impregnated oyster shell as a solid catalyst for soybean oil transesterification.

Research on inexpensive and green catalysts is needed for economical production of biodiesel. The goal of the research was to test KI-impregnated calcined oyster shell as a solid catalyst for transesterification of soybean oil. Specific objectives were to characterize KI-impregnated oyster shell, determine the effect of reaction variables and reaction kinetics. The catalyst was synthesized by impregnating KI on calcined oyster shells. X-ray diffraction analysis indicated the presence of portlandite and potassium iodide on the surface and a 31-fold increase in surface as a result of calcination and KI impregnation. Under the conditions tested, ideal reaction variables were 1 mmol g(-1) for catalyst loading, 50 °C for temperature, 10:1 for methanol/oil, and 4h for reaction time. The transesterification followed a first-order reaction (k=0.4385 h(-1)). The option of using oyster shell for the production of transesterification catalysts could have economic benefits to the aquaculture industry in the US.

Compositional and mechanical properties of peanuts roasted to equivalent colors using different time/temperature combinations.

Peanuts in North America and Europe are primarily consumed after dry roasting. Standard industry practice is to roast peanuts to a specific surface color (Hunter L-value) for a given application; however, equivalent surface colors can be attained using different roast temperature/time combinations, which could affect product quality. To investigate this potential, runner peanuts from a single lot were systematically roasted using 5 roast temperatures (147, 157, 167, 177, and 187 °C) and to Hunter L-values of 53 ± 1, 48.5 ± 1, and 43 ± 1, corresponding to light, medium, and dark roasts, respectively. Moisture contents (MC) ranged from 0.41% to 1.70% after roasting. At equivalent roast temperatures, MC decreased as peanuts became darker; however, for a given color, MC decreased with decreasing roast temperature due to longer roast times required for specified color formation. Initial total tocopherol contents of expressed oils ranged from 164 to 559 µg/g oil. Peanuts roasted at lower temperatures and darker colors had higher tocopherol contents. Glucose content was roast color and temperature dependent, while fructose was only temperature dependent. Soluble protein was lower at darker roast colors, and when averaged across temperatures, was highest when samples were roasted at 187 °C. Lysine content decreased with increasing roast color but was not dependent on temperature. MC strongly correlated with several components including tocopherols (R(2) = 0.67), soluble protein (R(2) = 0.80), and peak force upon compression (R(2) = 0.64). The variation in characteristics related to roast conditions is sufficient to suggest influences on final product shelf life and consumer acceptability.

Value-added processing of peanut skins: antioxidant capacity, total phenolics, and procyanidin content of spray-dried extracts.

To explore a potential use for peanut skins as a functional food ingredient, milled skins were extracted with 70% ethanol and filtered to remove insoluble material; the soluble extract was spray-dried with or without the addition of maltodextrin. Peanut skin extracts had high levels of procyanidin oligomers (DP2-DP4) but low levels of monomeric flavan-3-ols and polymers. The addition of maltodextrin during spray-drying resulted in the formation of unknown polymeric compounds. Spray-drying also increased the proportion of flavan-3-ols and DP2 procyanidins in the extracts while decreasing larger procyanidins. Spray-dried powders had higher antioxidant capacity and total phenolics and increased solubility compared to milled skins. These data suggest that spray-dried peanut skin extracts may be a good source of natural antioxidants. Additionally, the insoluble material produced during the process may have increased value for use in animal feed due to enrichment of protein and removal of phenolic compounds during extraction.

Peanuts, peanut oil, and fat free peanut flour reduced cardiovascular disease risk factors and the development of atherosclerosis in Syrian golden hamsters.

Human clinical trials have demonstrated the cardiovascular protective properties of peanuts and peanut oil in decreasing total and low density lipoprotein cholesterol (LDL-C) without reducing high density lipoprotein cholesterol (HDL-C). The cardiovascular effects of the nonlipid portion of peanuts has not been evaluated even though that fraction contains arginine, flavonoids, folates, and other compounds that have been linked to cardiovascular health. The objective of this study was to evaluate the effects of fat free peanut flour (FFPF), peanuts, and peanut oil on cardiovascular disease (CVD) risk factors and the development of atherosclerosis in male Syrian golden hamsters. Each experimental diet group was fed a high fat, high cholesterol diet with various peanut components (FFPF, peanut oil, or peanuts) substituted for similar metabolic components in the control diet. Tissues were collected at week 0, 12, 18, and 24. Total plasma cholesterol (TPC), LDL-C, and HDL-C distributions were determined by high-performance gel filtration chromatography, while aortic total cholesterol (TC) and cholesteryl ester (CE) were determined by gas liquid chromatography. Peanuts, peanut oil, and FFPF diet groups had significantly (P < 0.05) lower TPC, non-HDL-C than the control group beginning at about 12 wk and continuing through the 24-wk study. HDL-C was not significantly different among the diet groups. Peanut and peanut component diets retarded an increase in TC and CE. Because CE is an indicator of the development of atherosclerosis this study demonstrated that peanuts, peanut oil, and FFPF retarded the development of atherosclerosis in animals consuming an atherosclerosis inducing diet.

Value-added processing of peanut meal: aflatoxin sequestration during protein extraction.

The efficacy of a bentonite clay, Astra-Ben 20A (AB20A), to sequester aflatoxin from contaminated (approximately 110 ppb) peanut meal during protein extraction was studied. Aqueous peanut meal dispersions (10% w/w) were prepared by varying the pH, temperature, enzymatic hydrolysis conditions, and concentrations of AB20A. After extraction, dispersions were centrifuged and filtered to separate both the water-soluble and the water-insoluble fractions for subsequent testing. Inclusion of AB20A at 0.2 and 2% reduced (p < 0.05) aflatoxin concentrations below 20 ppb in both fractions; however, the higher concentration of AB20A also reduced (p < 0.05) the water-soluble protein content. Inclusion of 0.2% AB20A did not affect protein solubility, total soluble solids, or degree of hydrolysis. Peanut meal adsorption isotherms measured the AB20A capacity to sequester aflatoxin. These results are discussed in the context of a process designed to sequester aflatoxin from contaminated peanut meal, which could enable derivatives of this high protein material to be utilized in enhanced feed and/or food applications.