Capsaicin stability and bio-accessibility affected by complexation with high-amylose corn starch (HACS).

Delivery of pungent bioactives such as capsaicin from hot peppers is a scientific, technological and sensorial challenge. While capsaicin intake is positively related to various bowel diseases, its high pungency and instability upon digestion generate a problem in its delivery to the target organ. Helical V-amylose architectures have been shown to be a possible nano-sized delivery vehicle for such hydrophobic bioactives.

Transglutaminase modifies the physical stability and digestibility of chickpea protein-stabilized oil-in-water emulsions.

This study sought to utilize enzymatic crosslinking to modulate the properties of chickpea-stabilized o/w emulsions and determine its effect on digestibility. Oil-in water emulsions were produced from 40% corn oil and 6% chickpea protein (w/w) with/without addition of transglutaminase (TG). Crosslinking increased the particle size and poly-dispersity, and led to the formation of a gel-like structure (G' > G″) with 1.

Tyrosinase-crosslinked pea protein emulsions: Impact of zein incorporation.

The effect of tyrosinase-crosslinking of pea protein and pea-zein complexes on the properties of concentrated o/w emulsions was studied in the present work. Emulsions comprising 2% pea protein (w/w) solubilized in the aqueous phase (60% w/w) with or without zein solubilized in the oil phase (40% w/v), were fabricated by using high pressure homogenization. Tyrosinase treated emulsions (TyrBm-crosslinked) and non-crosslinked emulsions were evaluated after 2 h of incubation.

Oil-in-water emulsions stabilized by tyrosinase-crosslinked potato protein.

Potato protein (PP) holds great promise as a non-allergenic food ingredient with high nutritional value. Attempts to modulate its functional properties by crosslinking have not been reported to date. The effect of tyrosinase-mediated crosslinking of PP on the properties of o/w emulsions was studied in the present work.

Mechanistic insights into tyrosinase-mediated crosslinking of soy glycinin derived peptides.

Tyrosinase from Bacillus megaterium (TyrBm) was previously used to modulate soy glycinin-based emulsions and gels. To study the crosslinking mechanism, TyrBm oxidation of three tyrosine-containing octapeptides derived from glycinin was analyzed by oxygen consumption measurements, absorbance and mass spectrometry. A significant lag period and lower activity were measured when tyrosine was located in the middle of the peptide chain.

Modulating the gel properties of soy glycinin by crosslinking with tyrosinase.

The gelation progression and gel properties of enzymatically crosslinked soy glycinin were evaluated in comparison to non-crosslinked glycinin. Glycinin was initially crosslinked using tyrosinase from Bacillus megaterium (TyrBm) and was later used to form gel upon heating. Gelation was evaluated by small deformation rheological measurements and revealed a significant increase in storage modulus (G') obtained in the crosslinked gel.

Determination of tyrosinase substrate-binding modes reveals mechanistic differences between type-3 copper proteins.

Tyrosinase is responsible for the two initial enzymatic steps in the conversion of tyrosine to melanin. Many tyrosinase mutations are the leading cause of albinism in humans, and it is a prominent biotechnology and pharmaceutical industry target. Here we present crystal structures that show that both monophenol hydroxylation and diphenol oxidation occur at the same site.

Protein engineering of nirobenzene dioxygenase for enantioselective synthesis of chiral sulfoxides.

Nitrobenzene dioxygenase (NBDO) from Comamonas sp. is shown here to perform enantioselective oxidation of aromatic sulfides. Several para-substituted alkyl aryl sulfides were examined and it was found that the activity of the enzyme is dependent on the size of the substrate.