Edible insects: Cross-recognition of IgE from crustacean- and house dust mite allergic patients, and reduction of allergenicity by food processing.

BACKGROUND: Insects have become increasingly interesting as alternative nutrient sources for feeding humans and animals, most reasonably in processed form. Initially, some safety aspects - among them allergenicity - need to be addressed. OBJECTIVE: To reveal the cross-reactivity of shrimp-, mite- and flies-allergic patients to different edible insects, and further to assess the efficacy of food processing in reducing the recognition of insect proteins by patients' IgE and in skin prick testing of shrimp-allergic patients. METHODS: IgE from patients allergic to crustaceans, house dust mite or flies was evaluated for cross-recognition of proteins in house cricket Acheta domesticus (AD), desert locust Schistocerca gregaria (SG) and Yellow mealworm Tenebrio molitor (TM). Changes in IgE-binding and SPT-reactivity to processed insect extracts were determined for migratory locust (Locusta migratoria, LM), after different extraction methods, enzymatic hydrolysis, and thermal processing were applied. RESULTS: IgE from patients with crustacean-allergy shows cross-recognition of AD, SG and stable flies; house dust mite allergics' IgE binds to AD and SG; and the flies-allergic patient recognized cricket, desert locust and migratory locust. Cross-reactivity and allergenicity in SPT to LM can be deleted by conventional processing steps, such as hydrolysis with different enzymes or heat treatment, during the preparation of protein concentrates. CONCLUSION: The results show that crustacean-, HDM- and stable flies-allergic patients cross-recognize desert locust and house cricket proteins, and crustacean-allergic patients also flies proteins. Furthermore, this study shows that appropriate food processing methods can reduce the risk of cross-reactivity and allergenicity of edible insects.

Recovery of soluble proteins from migratory locust (Locusta migratoria) and characterisation of their compositional and techno-functional properties.

Edible insects emerged as an alternative source of high-quality proteins. Therefore, the effect of an extraction procedure for the recovery of migratory locust (Locusta migratoria) protein concentrate (MLPC) on the compositional characteristics and techno-functional properties was studied. The influence of pH value (2-10) and salt concentration (0, 1 and 3% w/v) on techno-functional properties was evaluated. Proteins were identified and characterized by RP-HPLC, SDS-PAGE and LC-MS/MS. The initial crude protein content of the whole locusts (65.9% on dry base) could be enhanced to 82.3% (MLPC). Solubility profiles of MLPC showed maximum solubility at pH9 (100%). Promising functionality comparable to egg white protein in terms of emulsifying activity at pH5, foamability at pH3 and 3% NaCl, and foam stability at pH9 were found. Consequently, MLPC offers a nutritious protein source with good functional properties at certain conditions, which could be used as food ingredient in a variety of food systems.

Immunoreactivity, sensory and physicochemical properties of fermented soy protein isolate.

The effect of induced liquid state fermentation (Bacillus subtilis, Rhizopus oryzae, Saccharomyces cerevisiae, Lactobacillus helveticus) on the immunoreactivity, physicochemical and sensory properties of soy protein isolate (SPI) was studied. L. helveticus revealed the most abundant reduction in terms of immunoreactivity within soluble protein fractions, up to 100%, which could be measured by in vitro sandwich ELISA using mouse monoclonal anti-Glym5 antibodies (mAbs). Almost no binding was found in western blot analysis using mouse monoclonal mAbs and sera from soy sensitive individuals. Fermentation increased water- and oil-binding capacity as well as protein solubility at pH 4.0. Foaming activity was nearly doubled compared to non-fermented SPI. A decreased emulsifying capacity, foaming density, and quantity of soluble proteins at pH 7.0 were observed. Principal component analysis (PCA) confirmed decreased bitter and beany off-flavors of fermented samples compared to non-fermented SPI. Consequently, fermentation might be a promising method to produce tasty low-allergen food ingredients with good physicochemical properties.

Enzymatic treatment of soy protein isolates: effects on the potential allergenicity, technofunctionality, and sensory properties.

Soybean allergy is of great concern and continues to challenge both consumer and food industry. The present study investigates the enzyme-assisted reduction in major soybean allergens in soy protein isolate using different food-grade proteases, while maintaining or improving the sensory attributes and technofunctional properties. SDS-PAGE analyses showed that hydrolysis with Alcalase, Pepsin, and Papain was most effective in the degradation of the major soybean allergens with proteolytic activities of 100%, 100%, and 95.9%, respectively. In the course of hydrolysis, the degree of hydrolysis increased, and Alcalase showed the highest degree of hydrolysis (13%) among the proteases tested. DSC analysis confirmed the degradation of major soybean allergens. The sensory experiments conducted by a panel of 10 panelists considered the overall improved sensory properties as well as the bitterness of the individual hydrolysates. In particular, Flavourzyme and Papain were attractive due to a less pronounced bitter taste and improved sensory profile (smell, taste, mouthfeeling). Technofunctional properties showed a good solubility at pH 7.0 and 4.0, emulsifying capacity up to 760 mL g(-1) (Flavourzyme) as well as improved oil-binding capacities, while the water-binding properties were generally decreased. Increased foaming activity for all proteases up to 3582% (Pepsin) was observed, whereas lower foaming stability and density were found. The hydrolysates could potentially be used as hypoallergenic ingredients in a variety of food products due to their improved technofunctional properties and a pleasant taste.