. & Cheftel, T. C. (1983): Enzymatichydrolysis of starch and cereal flours at intermediate moisture contents in continuous extrusion-reactor. Lebensm. Wiss. Technol. , 16 , 346-353.
Enzymatichydrolysis of starch and cereal flours
Authors:Urszula Sawicka, Wojciech Cisowski, Grażyna Matysik, and Adam Kowalczyk
Gradient thin-layer chromatography and densitometric determination have been applied to the qualitative and quantitative analysis of three phenolic acids — gallic acid, caffeic acid, and protocatechuic acid in three species from the
family. Free phenolic acids and those liberated after alkaline and enzymatic hydrolysis were analyzed.
Authors:R. Kumar, V. Choudhary, S. Mishra, and I. Varma
Optimum temperature and pH for the isolation of soy protein isolate (SPI) from soy protein concentrate (SPC) were established.
Enzymatic hydrolysis of SPI with enzymes of different specificities such as trypsin, chymotrypsin, papain and urease was carried
out and the products of hydrolysis were characterized by molecular mass determination [sodium dodecyl sulfate-polyacrylamide
gel electrophoresis (SDS-PAGE)] and thermal techniques [differential scanning calorimetry (DSC) and thermogravimetric analysis
(TG)]. Enzymatic hydrolysis resulted in a significant reduction in molecular masses. However the thermal stability of hydrolysed
SPI was similar to native SPI indicating that it is independent of molecular mass. DSC studies indicated an increase in temperatures
of endothermic transition associated with SPI denaturation and loss of absorbed moisture in samples of lower molecular masses.
Authors:Huan Zhang, Pan Wang, Ai-Jun Zhang, Xuan Li, Ji-Hong Zhang, Qi-Lian Qin, and Yi-Jun Wu
The housefly is an important resource insect and the housefly larvae are ideal source of food additives. The housefly larvae protein hydrolysates were obtained by enzymatic hydrolysis by alcalase and neutral proteinase. Their antioxidant activities were investigated, including the superoxide and hydroxyl radicalscavenging activity, 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, reducing power and metal chelating activity. The antioxidant activities of both hydrolysates increased with their increasing concentrations. The alcalase hydrolysate (AH) showed higher scavenging activities against hydroxyl radical and superoxide anion radical at low concentrations and higher metal-chelating activity than the neutral proteinase hydrolysate (NPH). The NPH exhibited higher scavenging activity against DPPH free radical and higher reducing power than the AH. Both hydrolysates showed more than 50% superoxide anion radical-scavenging activity at 10 μg/mL. These results indicate that both housefly larvae protein hydrolysates display high antioxidant activities and they could serve as potential natural antioxidant food additives.
Authors:F. Langmaier, J. Šivarová, M. Mládek, and K. Kolomazník
Condensation of dimethylol-urea (DMU) mixed with urea (U) and collagen hydrolysate (H), obtained through enzymatic hydrolysis of chrome-tanned leather waste, without added acid curing agents in the solid phase was studied through DSC and TG techniques in a temperature interval up to 220°C. Among both techniques TG proved be more useful.While the DMU+U mix produced methylene-oxide (-CH2-O-CH2-) and methylene (-CH2-) bridges at a ratio of approx. 1:1, urea substituted for collagen hydrolysate increased the proportion of more stable methylene bridges to methylene-oxide bridges to a ratio of approx. 2:1. Methylene-oxide bridges are considered to be the main potential sources of formaldehyde emissions from cured urea-formaldehyde type adhesives, and thus the use of collagen hydrolysate in preparation of urea-formaldehyde adhesive types is a suitable way how to make such adhesives more environmental friendly.
Enari, T. M. (1987): Enzymatichydrolysis of cellulose: Is the current theory of the mechanisms of hydrolysis valid? CRC Crit. Rev. Biotechnol , 5 , 67-87.
Enzymatichydrolysis of cellulose: Is the current theory of the
Grass is cultivated for bioenergy purposes yet and expected to play a more prominent role as a source of renewable energy
in the future. Understanding its burning characteristics is thus crucial to optimize the energetic efficiency. The aim of
this study was to reveal the effect of i) microbial decomposition and ii) enzymatic depolymerisation of grass on its thermal
behaviour. Thermal characteristics of grass during the course of aerobic decomposition and of fresh samples after treatment
by enzymatic hydrolysis were measured by differential scanning calorimetry (DSC). Heat of reaction, 50% burnoff values and
positions and areas of peaks were taken as indicators for the thermal behaviour. An increase in biochemical stability of the
grass during 140 days of decomposition was indicated by an exponential mass loss and decreasing specific CO2 respiration rates. Parameters representing the thermal stability of the materials coincided with this pattern. The relative
contribution of the thermolabile fraction decreased, and 50% burnoff values increased almost steadily during decomposition
from 366 to 407°C. These thermal stability parameters are thus indicators for biochemical degradation. However, peak temperatures
of the individual peaks continuously decreased during decomposition. A comparison of composted and fresh, cellulase-treated
samples without long-term microbial decomposition indicated that enzymatic depolymerisation rather than microbial consumption
of the plant tissue led to the observed decrease in peak temperatures.
., Zhang, Y. H. P. (2010) Bamboo saccharification through cellulose solvent-based biomass pretreatment followed by enzymatichydrolysis at ultra-low cellulase loadings. Biores. Technology 101 , 4926–4929.