Si-Yin Chung

Removing peanut allergens by tannic acid

Tannic acid (TA) forms insoluble complexes with proteins. The aims here were to remove major peanut allergens as insoluble TA complexes and determine if they would dissociate and release the allergens at pH 2 and 8 (gut pH). Release of the allergens in the gut could lead to absorption and consequently an allergic reaction. TA (0.25, 0.5, 1, and 2 mg/ml) was added to a peanut butter extract (5 mg/ml; pH 7.2), stirred, and centrifuged. The precipitates were then suspended in buffer at pH 2, centrifuged, re-suspended at pH 8, and centrifuged. Supernatants from each step were analysed by SDS-PAGE, ELISA, and Western blots. The effect of NaCl (1M) on complexes was also determined. Results showed that complexes formed at a TA concentration >0.5 mg/ml did not release major peanut allergens at pH 2 and 8, regardless of 1M NaCl being present or not. IgE binding of the extracts was reduced substantially, especially at a TA concentration of 1-2 mg/ml. Animal or clinical studies are still needed before TA can find an application in the development of low-allergen peanut products/beverages or the removal of peanut allergens due to accidental ingestion.

Reducing Food Allergy: Is There Promise for Food Applications?

Food allergy is on the rise and has become a growing food safety concern. The main treatment is strictly avoiding allergens in the diet. However, this is difficult to do because foods are sometimes contaminated with allergens due to processing of different foods with the same machinery. For this reason, accidental ingestion of trace amount of allergenic proteins is common. For children with severe food allergy, this could be life-threatening. Food products with reduced allergenic proteins, if developed, could be beneficial and may raise the threshold of the amount of allergenic proteins required to trigger an allergic reaction. As a result, the number of serious allergic reactions may decrease. Moreover, such less allergenic products may be useful or replace regular products in studies such as oral tolerance induction or early exposure experiments, where children with severe peanut allergy are usually excluded due to their severe intolerance. This review focuses on recent findings and progress made in approaches to reduce allergenic proteins in foods. Modifying methods may include physical and chemical treatments as well as lifestyle changes and the use of supplements. We discuss the benefits and drawbacks these methods present for production of hypoallergenic food products and food allergy prevention.

Reducing peanut allergens by high pressure combined with polyphenol oxidase

Polyphenol oxidase (PPO) has been shown to reduce major peanut allergens. Since high pressure (HP) can increase enzyme activity, we postulated that further reduction of peanut allergens can be achieved through HP combined with PPO. Peanut extracts containing caffeic acid were treated with each of the following: (1) HP; (2) HP+PPO; (3) PPO; and (4) none. HP was conducted at 300 and 500 MPa, each for 3 and 10 min, 37 °C. After treatment, SDS-PAGE was performed and allergenic capacity (IgE binding) was determined colorimetrically in inhibition enzyme-linked immunosorbent assay and Western blots, using a pooled plasma from peanut-allergic patients. Data showed that HP alone had no effect on major peanut allergens. However, HP at 500 MPa combined with PPO (HP500/PPO) induced a higher (approximately twofold) reduction of major peanut allergens and IgE binding than PPO alone or HP300/PPO. There was no difference between treatment times. We concluded that HP500/PPO at 3-min enhanced a twofold reduction of the allergenic capacity of peanut extracts, as compared to PPO itself.

IgE binding to peanut allergens is inhibited by combined d-aspartic and d-glutamic acids

The objective of this study was to determine if D-amino acids (D-aas) bind and inhibit immunoglobulin E (IgE) binding to peanut allergens. D-aas such as D-Asp (aspartic acid), D-Glu (glutamic acid), combined D-[Asp/Glu] and others were each prepared in a cocktail of 9 other D-aas, along with L-amino acids (L-aas) and controls. Each sample was mixed with a pooled plasma from peanut-allergic donors, and tested by ELISA (enzyme-linked immunosorbent assay) and Western blots for IgE binding to peanut allergens. Results showed that D-[Asp/Glu] (4 mg/ml) inhibited IgE binding (75%) while D-Glu, D-Asp and other D-aas had no inhibitory effect. A higher inhibition was seen with D-[Asp/Glu] than with L-[Asp/Glu]. We concluded that IgE was specific for D-[Asp/Glu], not D-Asp or D-Glu, and that D-[Asp/Glu] was more reactive than was L-[Asp/Glu] in IgE inhibition. The finding indicates that D-[Asp/Glu] may have the potential for removing IgE or reducing IgE binding to peanut allergens in vitro.

Simple methods to reduce major allergens Ara h 1 and Ana o 1/2 in peanut and cashew extracts

Abstract Whole peanut or cashew extracts are usually used in immunotherapy. Reducing major allergen(s) in the extracts may lessen their side effects. Three methods were evaluated to reduce major allergens in peanut extracts: (1) p‐aminobenzamidine; (2) magnetic agarose beads; and (3) extraction of a commercial peanut flour at pH 7, respectively. The first two methods were also used to reduce major allergens in cashew extracts. After treatments, samples were evaluated by SDS‐PAGE. pABA‐treated samples were also analyzed for IgE binding in western blot. We found that the methods resulted in peanut extracts lacking detectable Ara h 1 but containing Ara h 2/6 and cashew extract lacking Ana o 1/2, but containing Ana o 3. Consequently, reduced IgE binding was observed. We conclude that the methods are useful for producing peanut or cashew extract with little Ara h 1 or Ana o 1/2.