Physicochemical and functional properties of native and modified agave fructans by acylation.

Native agave fructans were modified by an acylation reaction with lauric acid. Native and modified fructans were characterized using NMR, FTIR and various physicochemical and functional properties at different pHs were evaluated. NMR and FTIR spectra demonstrated the incorporation of lauric acid in the molecular structure of fructans. Modified agave fructans exhibited a color, moisture and water activity similar to native fructans, but properties such as solubility, swelling capacity, emulsifying activity and foam capacity were significantly modified by the acylation reaction mainly when the samples were analyzed at different pHs. The thermogram of the acylated fructans evidenced significant changes in thermal properties when compared with native fructans and acylated fructans were able to form micellar aggregates. In general, modified fructans showed improved functional properties in comparison with native fructans representing an important opportunity to improve the functionality of the foods in which it is incorporated.

Integration of proteomics and metabolomics data of early and middle season Hass avocados under heat treatment.

Ripening heterogeneity of Hass avocados results in inconsistent quality fruit delivered to the triggered and ready to eat markets. This research aimed to understand the effect of a heat shock (HS) prior to controlled atmosphere (CA) storage on the reduction of ripening heterogeneity. HS prior to CA storage reduces more drastically the ripening heterogeneity in middle season fruit. Via correlation network analysis we show the different metabolomics networks between HS and CA. High throughput proteomics revealed 135 differentially expressed proteins unique to middle season fruit triggered by HS. Further integration of metabolomics and proteomics data revealed that HS reduced the glycolytic throughput and induced protein degradation to deliver energy for the alternative ripening pathways. l-isoleucine, l-valine, l-aspartic and ubiquitin carboxyl-terminal hydrolase involved in protein degradation were positively correlated to HS samples. Our study provides new insights into the effectiveness of HS in synchronizing ripening of Hass avocados.

A novel two-step enzymatic synthesis of blastose, a ß-d-fructofuranosyl-(2↔6)-d-glucopyranose sucrose analogue.

Blastose, a natural disaccharide found in honey, is usually found as a byproduct of fructo-oligosaccharide synthesis from sucrose with fructosyltransferases. In this study, we describe a novel two-step biosynthetic route to obtain blastose, designed from a detailed observation of B. subtilis levansucrase (SacB) acceptor structural requirements for fructosylation. The strategy consisted first in the synthesis of the trisaccharide O-ß-d-Fruf-(2↔6)-O-α-d-Glcp-(1↔1)-α-d-Glcp, through a regioselective ß-d-transfructosylation of trehalose (Tre) which acts as acceptor in a reaction catalyzed by SacB using sucrose or levan as fructosyl donor. In this reaction, levansucrase (LS) transfers regioselectively a fructosyl residue to either C6-OH group of the glucose residues in Tre. The resulting trisaccharide obtained in 23% molar yield based on trehalose, was purified and fully characterized by extensive NMR studies. In the second step, the trisaccharide is specifically hydrolyzed by trehalase, to obtain blastose in 43.2% molar yield based on the trisaccharide. This is the first report describing the formation of blastose through a sequential transfuctosylation-hydrolysis reaction.