Textural and rheological characteristics of sun-dried banana traditionally prepared in the north-east of Thailand

Traditionally prepared sun-dried bananas were evaluated for textural and rheological properties. Assessment of how those properties changed over a storage period of two months was also carried out. The texture analysis results that relate to large deformations of the product show that the samples were not significantly affected by storage for one month, but subsequent storage for an extra month did result in softer samples. Rheological characterisation shows that upon heating samples become more elastic, however, this behaviour was reversed upon cooling. The rheological behaviour did not change significantly over the two month storage period. Overall results indicate that textural changes are not the limiting factor in the shelf life of this product. Further work is recommended in order to improve our understanding and maximise the stability of the product over the anticipated shelf life

Effect of copper and iron fortifications on rheological properties of water-in-oil spreads containing κ-carrageenan

Work was undertaken to investigate the effect of copper and Iron fortification (up to 15 mM) on the rheology and firmness of water-in-oil spreads (60 % fat) produced using 0.25 % κ-carrageenan. The apparent viscosity of the aqueous phase (10.9 mPa s) was significantly reduced by fortification with 15mM copper (4 mPa s) or iron (3.2 mPa s) at 60°C. However, inclusion of minerals resulted in gelation of the aqueous phase at 6°C and increased the melting temperature on reheating. Copper addition at 7.5mM levels formed the strongest gel (storage modulus of 7.6 kPa) and increased the melting temperature of the aqueous phase from 21°C (control) to 49°C. At the higher levels of addition (7.5-15 mM), the minerals impaired the firmness at 6°C and rheology of the spreads on heating with copper inclusion resulting in the greatest reductions. The rheological and textural effects observed on fortification were attributed to the pro-oxidant effects of the metallic cations on the oil-phase of the spreads

Study of influential factors on oligosaccharide formation by fructosyltransferase activity during stachyose hydrolysis by pectinex ultra SP-L

The influence of reaction conditions for oligosaccharide synthesis from stachyose using a commercial enzymatic preparation from Aspergillus aculeatus (Pectinex Ultra SP-L) was studied. Oligosaccharides were analyzed by gas chromatography with flame ionization detection (GC-FID) and matrix-assisted laser desorption/ionization–time-of-flight–mass spectrometry (MALDI-TOF-MS). Galactosyl-melibiose (DP3) was synthesized as a result of fructosidase activity, whereas fructosyl-stachyose (DP5) and difructosyl-stachyose (DP6) were formed as a consequence of the fructosyltransferase activity of Pectinex Ultra SP-L. The optimal reaction conditions for the synthesis of penta- and hexasaccharides were 60 °C, pH 5.5, 600 mg/mL stachyose, and 34 U/mL enzyme. Reaction time played an important role in oligosaccharide mixture composition constituted by 20% DP5, 0.7% DP6, 55% stachyose, 21% galactosyl-melibiose, and 1% monosaccharides after 1 h and 16% DP5, 4% DP6, 27% stachyose, 44% galactosyl-melibiose, and 2% monosaccharides after 3 h. In conclusion, stachyose could be used as a substrate for the enzymatic synthesis of new oligosaccharides that may open new opportunities in the development of future prebiotics.This work has been financed under a R+D program of the Spanish Ministry of Science and Innovation Science, Projects AGL-2008-00941/ALI and Consolider Ingenio 2010 (FUN-CFOOD) CSD 2007-00063; a R+D program of the Comunidad de Madrid, Project ALIBIRD P2009/AGR-1469; and as a R+D program of the Comunidad de Castilla-La Mancha, POII10-0178-4685.Peer Reviewe