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The incidence of food allergy has been increasing over the years, leading to a demand for methods aimed to reduce allergens from food products. The study of food processing on allergen reactivity has largely focused on thermal treatments; however, novel food processing techniques, such as a variety of nonthermal methods, are being explored to potentially create hypoallergenic products. Nonthermal methods are oftentimes advantageous, as they have the ability to retain organoleptic properties, such as nutrient content and flavor, that are frequently altered during thermal processing. Those afflicted with food allergy are typically required to completely eliminate problem foods from their diet, yet potential processing methods may allow consumption of those condemned foods by offering products with reduced allergen potency. This review highlights the efficacy of postharvest thermal and nonthermal treatments of foods in their ability to alter food allergen reactivity.

Peanut allergy represents one of the most severe IgE-mediated reactions with food, but to date, the only effective way to prevent peanut allergy is total avoidance. If allergens could be mitigated during food processing before a product reaches the consumer, this would substantially lessen the food allergy problem. The efficacy of pulsed ultraviolet light (PUV), a novel food processing technology, on reducing peanut allergens, was examined. This study revealed for the first time that PUV was also capable of deactivating Ara h 2, the most potent allergenic protein of peanut. Protein extracts from raw and roasted peanuts were treated for 2, 4, and 6 min and peanut butter slurry was treated for 1, 2, and 3 min in a Xenon Steripulse XL 3000® PUV system. The distance from the central axis of the lamp was varied at 10.8, 14.6, and 18.2 cm. The SDS–PAGE showed a reduction in the protein band intensity for Ara h 1, Ara h 2, and Ara h 3 at the energy levels ranging from 111.6 to 223.2 J/cm 2 . Reduction of the protein band intensity for peanut allergens increased with treatment time but decreased with increased distance from the PUV lamp. The ELISA for peanut extracts and peanut butter slurry showed a reduction in IgE binding of up to 12.9- and 6.7-folds, respectively, compared to control.

Pulsed ultraviolet light (PUV), a novel technology most commonly used for microbial inactivation, has recently been employed to effectively mitigate food allergens in peanuts, soybean, shrimp, and almond. Putative mechanisms for the efficacy of PUV in reducing allergen reactivity include photothermal, photochemical, and photophysical effects. To date, there are no published data highlighting the effects of in vitro simulated gastric and intestinal digestion on the stability of PUV reduced allergen reactivity of food. In this study, PUV-treated shrimp extracts were subjected to simulated gastric fluid containing pepsin and simulated intestinal fluid containing trypsin and chymotrypsin, and then tested for changes in allergen potency. SDS-PAGE showed no major band deviation between undigested and digested PUV-treated shrimp extracts. IgE binding to tropomyosin remained markedly decreased as seen in Western blot analysis. Total shrimp allergen reactivity remained unchanged following in vitro peptic digestion and was markedly reduced following in vitro intestinal digestion as illustrated in indirect ELISA. The PUV reduced shrimp allergens remained at a low level under the in vitro simulated digestive conditions. The results inferred that PUV could be a potential method to create less allergenic shrimp products that would remain at a low allergen level under human gastric and intestinal digestive conditions.

Pulsed ultraviolet light (PUV), a novel food processing and preservation technology, has been shown to reduce allergen levels in peanut and soybean samples. In this study, the efficacy of using PUV to reduce the reactivity of the major shrimp allergen, tropomyosin (36-kDa), and to attenuate immunoglobulin E (IgE) binding to shrimp extract was examined. Atlantic white shrimp (Litopenaeus setiferus) extract was treated with PUV (3 pulses/s, 10 cm from light source) for 4 min. Tropomyosin was compared in the untreated, boiled, PUV-treated and [boiled+PUV]-treated samples, and changes in the tropomyosin levels were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). IgE binding of the treated extract was analyzed via immunoblot and enzyme-linked immunosorbent assay (ELISA) using pooled human plasma containing IgE antibodies against shrimp allergens. Results showed that levels of tropomyosin and IgE binding were reduced following PUV treatment. However, boiling increased IgE binding, while PUV treatment could offset the increased allergen reactivity caused by boiling. In conclusion, PUV treatment reduced the reactivity of the major shrimp allergen, tropomyosin, and decreased the IgE binding capacity of the shrimp extract.

Tempering has been shown in literature to preserve head rice yield after heated air drying. Most reported tempering work was done adiabatically at a temperature below that for rice drying. In this study, the effect of a tempering temperature above that for rice drying on the whole kernel percentage was investigated. High-temperature tempering is an effective way to preserve the whole kernel percentage for rice dried at a raised temperature (e.g., 60°C) at which head rice yield would otherwise incur a pronounced reduction without tempering. Tempering helped relax the strains inside a rice kernel induced by internal stresses developed during the drying process. The strains had two components (elastic component and viscous component) due to the viscoelasticity of rice kernels. The reduction of moisture content gradients inside a rice kernel during tempering helped eliminate the elastic component of the strains due to the elasticity of the rice kernel. Results showed that to effectively eliminate the viscous component of the strains due to the viscosity of the rice kernel, tempering temperatures must be kept well above the glass transition temperature of the rice kernel. A tempering temperature below the glass transition temperature failed to preserve the whole kernel percentage. For example, with a tempering temperature of 80°C and a tempering duration of 80 min, the whole kernel percentage for the rice with an initial moisture content of 20.4% wb dried at 60°C and 17% rh for 120 min down to 10.2% wb (10.2 percentage points of moisture content removal in one drying pass) was preserved to a level close to that of the control sample.

Peeling is one of the most important unit operations in tomato processing. Most recently, three novel tomato peeling methods were reported: infrared, ohmic heating and power ultrasound. Steam/hot water and lye peeling have been the most commercialized methods, but compared to steam peeling, lye peeling is more preferred and has gained widespread application among processors due to its association with higher product yields and better product quality. However, with the ever-tightening environmental protection laws, concerns have arisen in the recent years regarding lye usage as well as its disposal, which calls for alternative chemical-free peeling methods that can effectively peel the tomato while minimizing peeling losses and improving product quality. This review highlights the conventional methods used in tomato peeling, their efficacy and the potential applications of infrared, ohmic heating and power ultrasonics as a novel technology for tomato peeling.

Four different fresh and dried herb species (sage, thyme, mint and lemonbalm) were evaluated to study the effect of drying process on the total phenolics, antioxidant activity, flavonoid contents and color properties. Fresh mint had the highest contents of total phenolics (335.4 mg GAE/100 g), whereas lower levels were respectively found in sage (316.4 mg GAE/100 g) followed by lemonbalm (303.2 mg GAE/100 g) and thyme (299.2 mg GAE/100 g). Dry processing significantly decreased the phytochemical contents of all investigated herbs. Compare to air drying, total phenolics, antioxidant activity and flavonoids content in herbs decreased apparently by oven dried. Fresh mint had the highest antioxidant activity (87.46%) and flavonoids content (298.51 mg CE/100 g), while the fresh sage, thyme and lemonbalm were found to have antioxidant activity values of 86.81%, 86.56% and 85.26%, respectively. Results showed that air drying herbs contained more total phenolics, antioxidant activity, and flavonoids than oven drying herbs.

Rancidity due to the lipid oxidation process is a critical factor influencing the quality of roasted peanuts. Sonication in combination with edible coatings added with plant extracts may extend the oxidative stability of peanuts. Peanuts were roasted at 178°C for 15 min, subjected to sonication in hexane for 10 min, and then coated with carboxymethyl cellulose (CMC) solution mixed with rosemary, tea extracts, and α-tocopherol and stored at 35°C for 12 weeks. The oxidative stability of the samples was investigated by measuring the oxidative stability index. Reduction in oxidation of 66.1% and 10.4% was observed for samples roasted and coated with extracts of rosemary and tea, respectively, as compared to uncoated sample. However, the oxidative stability of samples roasted-sonicated and coated with extracts of rosemary and tea was improved by 100.7% and 28.1%, respectively, in relation to the control. Sonication beyond coating improved the oxidative stability of the samples mixed with rosemary, tea extracts, and α-tocopherol by 10.3%, 12.1%, 34.6%, and 17.7%, respectively. The L * , a * , and b * values indicated that the peanut coated with CMC mixed with rosemary, tea extracts, and tocopherol at different concentration levels did not have significant (P < 0.05) color change during the 12-week storage at 35°C.

The efficacy of pulsed ultraviolet light (PUV) and high hydrostatic pressure (HHP) on the IgE binding to the almond extracts was studied using sodium dodecyl sulfate polyacrylamide-gel electrophoresis, Western blot, and enzyme-linked immunosorbent assay (ELISA) probed with human plasma containing IgE antibodies to almond allergens and a polyclonal antibody against almond major protein. Crude almond protein extracts were treated with PUV (3 pulses/s, 10 cm from lamp) for 0.5, 1, 2, 3, 4, 6, 7, and 10 min. In comparison, boiling treatments were also carried out. The HHP treatments were conducted at 600 MPa for 5, 15, and 30 min at three temperatures of 4 °C, 21 °C, and 70 °C. Western blots and indirect ELISA demonstrated a reduction in the levels of allergens and IgE binding in PUV-treated extracts at 7 min, which was found to be the optimal time for PUV exposure. Boiling was not as effective as PUV in reducing the overall IgE-binding of the almond extracts. Unlike PUV, HHP did not affect the allergen levels and IgE binding under the conditions tested.