Fibrous growth of tricalcium phosphate ceramics

Structural transformation and sintering processes of tricalcium phosphate (TCP) ceramics prepared from defective hydroxyapatite (Ca9HPO4(PO4)5OH) were studied by X-ray diffraction (XRD) and atomic force microscopy (AFM). Starting powders with Ca/P ratio 1.5 were obtained by adding 0.5 l of 0.3 M H3PO4 solution to an equal volume of 0.45 M Ca(OH)2. In the prepared ceramics, the onset temperature for transformation of defective hydroxyapatite into TCP (witlokite) agrees with the onset temperature for sintering (800 °C). Sintering occurs through the formation of a fibrous structure, which resembles biological hard tissue. In the 1000–1200°C range, these fibres coalesce into grains of up to 0.6 m in size with a fibrous-laminar morphology. At the end of this sintering stage witlokite transforms into TCP. At about 1450°C, partial decomposition of TCP into Ca2P2O7+Ca4P2O9 is observed. AFM observations suggest that Ca2P2O7 is segregated in the liquid state and increases the velocity of grain growth (up to 12 m).     

Non-thermal plasma for exhaust gases treatment

This article describes a study on a non-thermal plasma device to treat exhaust gases in an internal combustion engine. Several tests using a plasma device to treat exhaust gases are conducted on a Honda GX200-196 cm³ engine at different rotational speeds. A plasma reactor could be efficient in degrading nitrogen oxides and particulate matter. Monoxide and carbon dioxide treatment is minimal. However, achieving 1%–3% degradation may be interesting to reduce the emission of greenhouse gases.     

PARTIAL CHARACTERIZATION OF A WHEY PROTEIN CONCENTRATE AND ITS ENZYME HYDROLYSATES

A whey protein concentrate (WPC) was produced from fresh whey by ultrafiltration (MW cut off 10 kDa) and lyophilization. Enzymatic hydrolysis was performed with three enzyme systems: pancreatin (PA), protamex (PR) or alcalase 0.6L (AL) to produce hydrolysates with 20% degree of hydrolysis (DH). The peptide profiles of the hydroly sates were determined by high performance capillary electrophoresis (HPCE). The relationship between enzyme system and preferential protein substrate could be established. The alcalase hydrolysate (ALH) differed from the other two hydrolysates, and the enzyme showed the lowest specificity for β‐lactaglobulin. Considering the protein content from WPC the pancreatin hydrolytic system was the most efficient leaving only 4.69% unhydrolyzed protein in the final hydrolysate (PAH). For 20% degree of hydrolysis alcalase left 7.98% unhydrolyzed protein, while protamex left 9.81% unhydrolyzed protein in the final hydrolysate.     

BIOLOGICAL VALIDATION OF TOMATO PULP CONTINUOUS HEAT PROCESS

This research validated the commercial process applied to tomato pulp (pH 4.3 and 8 Brix) packed in Tetra Brik packages. Spores of Bacillus coagulans and Neosartorya fischeri were selected as targets. The heat resistance of both microorganisms, tested independently, was compared. The redesigned thermal processes were carried out in a aseptic processing and tested by indirect inoculation and retrieval with spores immobilized in alginate/tomato balls. The results showed that processes for 30 s at 115C or greater did not allow the survival of heat‐resistant molds. For bacterial spores, processes for 30 s at 109C or greater showed no survivors. Although, 30 s at 115C will control both types of spoilage spores, concern for possible C. botulinum growth attributed to metabiosis in product with varying initial populations of molds and residual oxygen content dictated, a process recommendation of 60 s at 126C for safety reasons.     

Hydrophilic and Rheological Properties of Brewer's Yeast Protein Concentrates

Protein solubility (PS), water-holding capacity (WHC), viscosity and gelling properties were studied in brewer's yeast protein concentrates prepared by 3 procedures: isoeletric precipitation of protein (I-PC), extraction with 0.5M NaClO₄(P-PC) or with 3% sodium trimetaphosphate (TMP-PC). PS was higher for TMP-PC and lower for P-PC at pH 4 to 12. WHC increased with increasing pH in all concentrates, but was higher for TMP-PC. The presence of NaCl (0.1 M and 1.0M) reduced to 50% the WHC of TMP-PC. Gelling properties of a 10% protein dispersion were studied in the TMP-PC preparation. Hardness and fracturability of the gel (TA-XT2 texturometer) was 35 and 31 gf, respectively. Apparent viscosity of a 3% dispersion at pH 7.0 was lower for I-PC and higher but similar for TMP-PC and P-PC. All concentrates showed pseudoplastic rheological behavior.