C12 C14 Research Articles

Effects of lipolytic enzymes Pseudomonas fluorescens on liberation of fatty acids from milk fat

Effects of thermostable lipolytic enzymes Pseudomonas fluorescens 66 ZB in pasteurized milk on concentration of free fatty acids (VMK) in milk were studied in selected milk samples. Identical bulk milk samples were analysed by the method specified in previous papers (Vyletělová et al. 1999a, b, 2000). Reference milk samples (without bacterial strains) and the experimental ones (containing Ps. fl. 150 th. CFU/ml and 2800 th. CFU/ml, resp.) were stored at 6.5°C and 14°C and analysed at regular time intervals (24 h) – Table 1. An extractive-titric method (Kadlec et al. 1996; Table 2 and Fig. 2) was used for monitoring of fatty acid (MK) liberation. Precise analyses of MK and VMK were made by the chromatographic method (Figs. 1, 3 and 4). Medium-chain fatty acids (C12–C16) are liberated first of all; short-chain acids (C6–C10) were found sporadically or in very small quantities (Table 2). Dissociation constant of the specific fatty acid liberated from milk fat affects principally relationships between pH and free fatty acid concentration. The predominating proportion of long-chain acids in liberated fatty acid formation is associated with lower reduction of pH as compared to the predomination of fatty acids with shorter chains associated with more substantial reduction of pH. In our study, a rapid decrease of pH was noted before 168 h (Table 24); this corresponds to low concentrations of short-chain free fatty acids. Vyletělová et al. (2000) found significant relations between pH and contents of VMK (measured by the extractive-titric method); in some samples, correlation coefficients amounted to r = –0.93*** (P £ 0.001). The extractive-titric method analysing VMK concentrations (mmol/kg milk fat) provides results characterized by a systematic rise (e.g., 32.0 mmol/kg instead of 13.0 mmol/kg in raw milk). According to Kratochvíl (1992) 20 mmol VMK/kg milk fat signalized the starting point characterizing flavour degradation of milk caused by activities of fatty acids C12–C14 above all; the transformed value (respecting specifics of the extractive-titric method) amounts to 49 mmol/kg. In case of higher storage temperature a significant break is found after 144 h; in case of lower temperature this break is after 192 h (Table 2). Limits determining potential lipolytic modifications of milk flavour (RLZCHV) as related to specific samples and temperatures at VMK levels amounting to 49 mmol/kg or 20 mmol/kg are outlined in Fig. 2. Milk samples No. 5 and No. 6 stored at higher temperature surpassed this risk limit at 56 h and 64 h, respectively (Table 2, Fig. 2). On the contrary, milk samples stored temperatures corresponding to the standard storage temperature (storage of raw milk, transport, storage of pasteurized milk) surpass the mentioned risk level after 90 h and 140.5 h. Obtained results document the predominant role of storage temperature in the whole complex (production and processing of milk as a raw material or an intermediate product); evident differences in contamination rates (105 an 106) can be characterized as secondary effects in this case (Table 2). As related to practical conditions, the mentioned facts imply immediate processing of raw milk and pasteurized milk. This postulate must be respected namely by dairy plants producing delicate milk products. Vyletělová et al. (2000) found a notable VMK increase/24 h (7–11 mmol/kg milk fat) under specific temperatures and microbial contamination.

Studies on viscosity build-up properties of sodium alcohol ether sulphates

Narrow and broad range distributed ethoxylates of linear C12–C14 alcohols were synthesised using a calcium-based unconventional catalyst and NaOH, respectively. Their composition was determined by gas chromatography. Sulphates were synthesised in the traditional way by reaction of ethoxylates with sulphur trioxide in a film reactor and neutralised with sodium hydroxide. Products were characterized by the ethoxylate homologue distributions and acid value of the intermediate sulphuric acid derivatives. Viscosity build-up properties of the narrow and broad range distributed ethoxylates-based sodium alcohol ether sulphates were studied. Effects of ethoxylate homologue distribution were compared with those of average ethoxylation grade and sulphation degree. It was shown that the acid number of the obtained sulphates, ethoxylate homologue distribution, average polyaddition degree and sodium chloride content influenced remarkably the thickening ability of ethoxylates. Furthermore, it was found that the limited content of the longer ethoxylate chains in narrow range distributed alcohol ethoxylates is responsible for enhanced viscosity build-up properties of their sodium sulphate derivatives. The following empirical relationship was obtained: log η = (2.99 ± 1.25) + (3.78 ± 0.86) × 10−2V − (1.48± 0.15)Nav − (2.69 ± 0.7) × 10−2AN + (0303 ± 0.058) × Csurf + (0.832 ± 0.041) × CNaCl where η is the viscosity in cP, V is the distribution coefficient, Nav is the average oxyethylation degree, AN is the acid number of alcohol ether sulphuric acid and Csurf and CNaCl are concentrations (wt%) of the studied surfactants and sodium chloride, respectively. © 1999 Society of Chemical Industry

(±)-6,7-Dihydro-1,6,11-trimethyl-5H-dibenz[c,e]azepine

In the title compound, C17H19N, the central seven-membered azepine ring adopts a twisted boat conformation. The molecule exhibits a huge deviation from planarity by rotation of the two fused ortho-methyl-substituted phenyl rings around the central C12—C14 single bond. The dihedral angle between the planes of these two rings amounts to 56.05 (4)° with a cisoid arrangement around the C12—C14 bond. Because of this non-planarity, the molecule is axially chiral.

Purification and partial characterization of an alkaline lipase from Pseudomonas pseudoalcaligenes F-111.

An extracellular alkaline lipase of alkalophilic Pseudomonas pseudoalcaligenes F-111 was purified to homogeneity. The apparent molecular weight determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was 32,000, and the isoelectric point was 7.3. With p-nitrophenyl esters as its substrates, the enzyme shows preference for C12 acyl and C14 acyl groups. It was stable in the pH range of 6 to 10, which coincides with the optimum pH range.

Effect of alkali on filaments of poly(ethylene terephthalate) and its copolyesters. II. Presence of quaternary ammonium salt in the alkali‐bath

AbstractInfluence of alkyl (C12–C14)‐dimethyl‐benzyl ammonium chloride in the solution of sodium hydroxide on the hydrolysis of poly(ethylene terephthalate) (PET), anionically modified poly(ethylene terephthalate) copolyster (CDP), and block polymer of poly(ethylene terephthalate)‐poly(ethylene glycol) (EDP), has been studied under a variety of proportions, concentrations, time and temperature of reaction, M : L ratio, etc. Mechanical properties of treated polymeric materials are evaluated. Hydrolysis of two polymers in the same bath is compared with that in separate baths.

Fatty acid composition of seed oils of some members of the meliaceae and combretaceae families

AbstractSeed oils of some members of the Meliceae (six) and Combretaceae (three) were analyzed for their fatty acid composition. In oils of members of both families palmitic acid was the most abundant saturated acid. Trace amounts of short chain (C12–C14) and long chain (C20–C22) saturated acids were detected in some members of the two families. Oleic acid was the most abundant unsaturated acids in the oils of four members of the Meliaceae. However, in the oils ofCedrella odorata andLovoa trichilloides, dienoic acid (C18:2) was the major unsaturated acid. Strikingly high levels of trienoic (C18:3) and monoenoic (C16:1) acids were detected in the seed oils ofC. odorata andEnthandrophragma angolense, respectively. Oleic acid also was the most abundant unsaturated acid in the Combretaceae. The nutritional value and industrial potentials of these oils are given.

Role of CA2+ ion in the abortifacient action of prostaglandins. II. Molecular orbital and conformation energy calculations of PGA1

AbstractThis paper reports some theoretical studies of PGA1 using conformational and molecular orbital techniques. The conformation energy (CE) calculations, using empirical potential‐energy functions, for intrinsic torsional rotations around C12C13 (θ), C7C8 (Ψ), and C14C15 (ϕ) show a number of energy minima. The relative value of the CE for these minima ranges from 4.09 to 8.01 kcal/mol. An additional rotation around C4C5 (χ) giving “twist” to the carboxyl chains lowers the CE value by 2–3 kcal/mol and a conformation with CE value 2.39 kcal/mol less than crystallographic one is obtained. The interchain interaction energy showed changes with conformations. No significant change in the interchain interaction energy was observed due to “twist” in the carboxyl chain. The isopotential mapping study demonstrated the probable ionic binding site near the carboxyl and the ring (O9) oxygens. Conformational and molecular orbital results are discussed in the light of the reduced abortifacient potency of PGA1 with respect to PGF2α and the possible role of Ca2+ ions in this action.

Foam performance of fatty acid soaps of odd carbon numbers

AbstractThe foam capacities, foam stabilities, expanding single bubble stabilities, surfact tensions, and surface viscosities of the straight chain C9–C14 sodium soaps were measured at various concentration. The C12–C14 soaps, most notably the C13, gave the best over‐all foam performance of the compounds studied. The critical micelle concentrations for these soaps were also determined.

Effect of composition of oils and synthetic fatty acids on properties of lithium greases

1. The thickening effect of lithium soaps of synthetic fatty acids and the properties of greases based on them depend both on the structure and fractional composition of the acids, and also on the composition of the dispersion medium. 2. An extreme type of dependence of the thickening effect of Li soaps on molecular weight of synthetic fatty acids has been discovered, similar to that established for the Li soaps of individual acids. 3. Dearomatization of oils leads to a reduction in the thickening effect of Li soaps and to a shift in its optimum to soaps of higher molecular weight acids. For commercial oils having a naphthene-aromatic base, this optimum corresponds approximately to soaps of C12–C14 acids; and for naphthene-paraffinic or naphthenic oils, to soaps from C16–C18 acids.

Compound formation in binary fatty-acid mixtures

Long crystal spacings d 1 and short spacings d 2 and d 3 of C 12 –C 14 , C 14 –C 16 and C 16 –C 18 fatty - acid mixtures have been determined using a high resolution X -ray diffractometer in an attempt to elucidate the question of compound formation in these mixtures. Both d 1 and d 3 spacings showed significant changes in relation to the composition of the mixtures whereas d 2 spacings remained practically unchanged. The changes in d 1 and d 3 spacings are interpreted as denoting limited intersolubility of the component fatty acids and partial compound formation. Numerical correlation found between the above changes seems to indicate a shortening of the distance between alternate carbon atoms of the higher melting component in mixtures containing 30 to 70 mol. percent of this component.