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Lower pH Values (lower + ph_value)
Selected AbstractsTHE EFFECT OF MODIFIED ATMOSPHERE PACKAGING ON THE QUALITY AND SHELF LIFE OF FRANKFURTER TYPE-SAUSAGESJOURNAL OF FOOD QUALITY, Issue 2010NALAN GOKOGLU ABSTRACT The effects of modified atmosphere packaging on the quality and shelf life of frankfurter-type sausages, prepared exclusively from beef meat, were investigated. Sausages were packed under varying modified atmosphere conditions (30% CO2/70% N2; 70% CO2/30% N2; 100% CO2; 80% CO2/20% O2) and vacuum, and stored at 4C for 28 days. Lower pH values were observed in the samples packed under modified atmospheres compared to vacuum. Inhibition effect of carbon dioxide concentration on the oxidation was seen. Carbon dioxide caused microbial inhibition. The lowest total viable count was found in the samples packed under 100% CO2. It was concluded that modified atmosphere packaging had significant effect on the quality and shelf life of frankfurter-type sausages compared to vacuum packaging. The most suitable atmosphere among the tested atmospheres was that with 70% CO2, 30% N2 atmosphere. The shelf life of sausages under this atmosphere was 28 days. PRACTICAL APPLICATIONS Meat and meat products are susceptible to spoilage. Several preservation techniques are used to extend their shelf life. Packaging of fresh meat is a common application to protect its quality. Modified atmosphere packaging (MAP) means to replace the air in a package of food with some different mixture of gases. The success in MAP is to choose the suitable gas combination, packaging system, package application and the package material. Proper gas combination to keep meat quality should be provided. Several studies have been performed to extent shelf life of pork sausages and local-type sausages using modified atmosphere packaging technique. However there is no data on beef sausages. The results of this research will form the basis for further studies and also will be beneficial for industry. [source] Ensilage of wilted whole crop rice (Oryza sativa L.) using a roll baler for chopped material: Silage quality in long-term storageGRASSLAND SCIENCE, Issue 2 2007Hidenori Kawamoto Abstract We examined the effects of long-term storage on the fermentation quality, chemical composition, and digestibility of wilted whole crop rice silage prepared using a roll baler for chopped material (set chop length, 13 mm) and compared the results with those obtained by using a conventional roll baler. The roll balers were used for ensiling whole crop rice of three types: (i) dough-ripe stage with light wilting (45% dry matter); (ii) dough-ripe stage with heavy wilting (65% dry matter); and (iii) yellow-ripe stage with light wilting (45% dry matter). The apparent dry matter density was higher in the ensiled roll bales composed of chopped whole crop rice (chopped bales) than in those composed of non-chopped whole crop rice (conventional bales) (195,250 kg m,3 vs 156,218 kg m,3, respectively). The formation of volatile fatty acids and ammonia-nitrogen was low in all types of silage. Further, no marked differences in the chemical composition and apparent dry matter digestibility were observed between silage from the two types of bales. However, there were significant differences in their lactic acid and ethanol contents. The lactic acid production in the conventional silage was low (0.08,0.14% fresh matter), whereas that in the chopped silage was high (0.71,0.97% fresh matter). A lower pH value (pH 4.0,4.3) was retained in the chopped silage after 10 months of storage. High ethanol production (1.1,2.5% fresh matter) was observed in the conventional silage, whereas ethanol production decreased to less than 1% in the chopped silage. These results indicate that although the ethanol fermentation is readily enhanced in the ensilage of wilted whole crop rice performed by a conventional baler, the ensilage performed by a baler for chopped material encourages lactic acid fermentation and suppresses ethanol production over a wide moisture range throughout the long-term storage. [source] Preparation and characterization of PEGylated terlipressinJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Xiufang Wang Abstract Terlipressin was chemically modified by reaction with succinimidyl propionate- monomethoxy polyethylene glycol (mPEG-SPA). To determine the PEGylated degree, the position and the optimized condition for PEGylated terlipressin, the reactions were monitored in different pH value buffers at different molar ratios by reversed-phase high performance liquid chromatography (RP-HPLC). Tryptic digestion and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used. The results showed that the amount of mono-PEG-terlipressin was higher at lower pH value and lower content of PEG. Meanwhile, the amount of di-PEG-terlipressin was higher at higher pH value and higher content of PEG under the conditions investigated. The position of PEGylated terlipressin was confirmed by tryptic digestion. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Activation of gelatinolytic/collagenolytic activity in dentin by self-etching adhesivesEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2 2006Yoshihiro Nishitani Mild acids are known to activate dentin matrix metalloproteinase (MMPs). All self-etching dental adhesives are acidic (pH 1.5,2.7) and may activate dentin MMPs. The purpose of this study was to compare the ability of several all-in-one adhesives to activate gelatinolytic and collagenolytic activities in powdered mineralized dentin. Powdered dentin made from human teeth was mixed with all-in-one adhesives (Clearfil Tri-S Bond, G-Bond, Adper Prompt L-Pop) or a self-etching primer (Clearfil SE Bond primer) for varying times and then the reaction was stopped by extracting the adhesives using acetone. Fresh untreated mineralized dentin powder had a gelatinolytic activity of 3.31 ± 0.39 relative fluorescent units (RFU) per mg dry weight (24 h) that increased, over storage time, to 87.5 RFU mg,1 (24 h) after 6,8 wk. When fresh powder was treated with acidic Tri-S Bond, the gelatinolytic activity increased from 3.24 ± 0.70 RFU mg,1 to >,112.5 RFU mg,1 (24 h) after 20 min and then remained unchanged. Monomers with lower pH values produced less activity. There was a significant, direct correlation between gelatinolytic activity and pH, with Tri-S giving the highest activity. Coating dentin powder with Tri-S resin prevented fluorescent substrates from gaining access to the enzyme, even though it activated the enzyme. In conclusion, self-etch adhesives may activate latent MMP and increase the activity to near-maximum levels and contribute to the degradation of resin,dentin bonds over time. [source] EFFECT OF SOLUBLE POLYLACTIC ACID DURING REFRIGERATED STORAGE OF GROUND MEATS INOCULATED WITH ESCHERICHIA COLI O157:H7,JOURNAL OF FOOD SAFETY, Issue 1 2000ANN ALLANSON ABSTRACT Ground beef, ground pork, and commercial breakfast sausage were inoculated (6.5 log10 CFU/mL) with a five strain mixture of Escherichia coli 0157:H7 and treated either with sterile water, or 1% or 2% solutions of soluble polylactic acid (SPLA) in sterile water and stored at 4C for 1, 24, 72 and 168 h. After 168 h, 2% SPLA was significantly (p0.05) more effective than both 1% SPLA and sterile water in reducing E. coli 0157:H7 and resulted in overall reductions of 1.68, 1.70, and 1.32 log10 CFU/mL for beef, pork, and pork sausage, respectively, when compared to control samples. The meat samples treated with 1% and 2% SPLA maintained significantly (p 0.05) lower pH values throughout refrigerated storage of 168 h with the higher concentration sustaining pH values from 3.83 to 3.92. Although the inhibitory effect of this acid increased with storage time, E. coli 0157:H7 survived these acidic conditions, with water activity levels ranging from 0.972 to 0.991. [source] Core-Shell Biopolymer Nanoparticles Produced by Electrostatic Deposition of Beet Pectin onto Heat-Denatured ,-Lactoglobulin AggregatesJOURNAL OF FOOD SCIENCE, Issue 6 2008R. Santipanichwong ABSTRACT:, The purpose of this study was to produce and characterize core-shell biopolymer particles based on electrostatic deposition of an anionic polysaccharide (beet pectin) onto amphoteric protein aggregates (heat-denatured ,-lactoglobulin [,-lg]). Initially, the optimum conditions for forming stable protein particles were established by thermal treatment (80 °C for 15 min) of 0.5 wt%,-lg solutions at different pH values (3 to 7). After heating, stable submicron-sized (d= 100 to 300 nm) protein aggregates could be formed in the pH range from 5.6 to 6. Core-shell biopolymer particles were formed by mixing a suspension of protein aggregates (formed by heating at pH 5.8) with a beet pectin solution at pH 7 and then adjusting the pH to values where the beet pectin is adsorbed (< pH 6). The impact of pH (3 to 7) and salt concentration (0 to 250 mM NaCl) on the properties of the core-shell biopolymer particles formed was then established. The biopolymer particles were stable to aggregation from pH 4 to 6, but aggregated at lower pH values because they had a relatively small ,-potential. The biopolymer particles remained intact and stable to aggregation up to 250 mM NaCl at pH 4, indicating that they had good salt stability. The core-shell biopolymer particles prepared in this study may be useful for encapsulation and delivery of bioactive food components or as substitutes for lipid droplets. [source] Effect of pH on synthesis and properties of perovskite oxide via a citrate processAICHE JOURNAL, Issue 2 2006Zhentao Wu Abstract A series of La0.6Sr0.4Co0.4Fe0.6O3-, (LSCF) perovskite-type oxides were synthesized using a modified citrate process under various pH conditions (pH =1, 3, 5, 7, and 9, respectively). The effect of pH on the chelate process, crystal development, morphology, and oxygen permeability of LSCF oxides were investigated. FT-IR analysis showed that the chelate processes for pH = 1 and 3 were different from those for pH = 5, 7, and 9. XRD and SEM observations revealed that the crystal formation and morphology of LSCF oxides were dependent on the precursors with different pH conditions. The LSCF membranes derived from the precursors with lower pH values (pH = 1 and 3) exhibited larger apparent activation energy for oxygen permeation than the other samples (pH = 5, 7, and 9) in the range of 1073-1123K. This study indicated that properties such as crystallinity and oxygen permeability of LSCF oxide could be tailored by controlling the pH values in the synthesis process. © 2005 American Institute of Chemical Engineers AIChE J, 2006 [source] Protein dynamics control proton transfer from bulk solvent to protein interior: A case study with a green fluorescent proteinPROTEIN SCIENCE, Issue 7 2005Anoop M. Saxena Abstract The kinetics of proton transfer in Green Fluorescent Protein (GFP) have been studied as a model system for characterizing the correlation between dynamics and function of proteins in general. The kinetics in EGFP (a variant of GFP) were monitored by using a laser-induced pH jump method. The pH was jumped from 8 to 5 by nanosecond flash photolysis of the "caged proton," o -nitrobenzaldehyde, and subsequent proton transfer was monitored by following the decrease in fluorescence intensity. The modulation of proton transfer kinetics by external perturbants such as viscosity, pH, and subdenaturing concentrations of GdnHCl as well as of salts was studied. The rate of proton transfer was inversely proportional to solvent viscosity, suggesting that the rate-limiting step is the transfer of protons through the protein matrix. The rate is accelerated at lower pH values, and measurements of the fluorescence properties of tryptophan 57 suggest that the enhancement in rate is associated with an enhancement in protein dynamics. The rate of proton transfer is nearly independent of temperature, unlike the rate of the reverse process. When the stability of the protein was either decreased or increased by the addition of co-solutes, including the salts KCl, KNO3, and K2SO4, a significant decrease in the rate of proton transfer was observed in all cases. The lack of correlation between the rate of proton transfer and the stability of the protein suggests that the structure is tuned to ensure maximum efficiency of the dynamics that control the proton transfer function of the protein. [source] | ||||||||||