Development of economical processes was necessary to commercialise this technology for the manufacture of cosmetic ingredients. Enzymatic production methods had to be established which could compete against standard established chemical synthetic methods. Now relatively simple esters are being produced enzymatically. Extensive purification procedures to clean up products after high temperature reaction steps are not required. Product quality and specifications, such as the acid and hydroxy values of commercial ester products, could be improved. Examples of products manufactured with better purity and yields in economical and ecologically friendly processes are decyl oleate, cetyl ricinoleate, myristyl myristate and decyl cocoate.

Thermostable esterases are used in biocatalysis for the synthesis of a variety of products, for example, flavour esters, emulsifiers, or pharmaceutical intermediates. Industrial enzymatic conversions to obtain chemo-, regio-, and stereoselective transformations may require thermostable enzymes active in organic solvents at high temperatures. To find novel enzymes for industrial bioconversions, we have used a new generation of thermostable reporter substrates (CLIPS-O for CataLyst Identification ProcesS per Oxidization) to screen for esterase activity in thermophilic microorganisms belonging to various thermophilic genus. One of the strains (belonging to Thermus genus) exhibiting activity on short- and long-chain ester CLIPS-O substrates has been selected. The genomic library of this strain was screened using a high-throughput functional technology. Positive clones expressing esterases active at high temperature were immediately characterized during screening for chain-length specificity.

In this work, the enzyme-catalyzed degradation of hyperbranched polyesters (HBPEs) was investigated. Enzymatic degradation experiments were performed in a phosphate buffer in the presence of the lipases Candida cylindracea, Pseudomonas cepacia, Novozym 388, Amano CE, Lipomod 34P, and Cal-B, whereas control experiments were performed in the same system without lipases. The extent of polymer degradation was determined by quantification of the released free fatty acids by gas chromatography. The influence of the alkane chain length and the number of alkane chain end groups on the lipase-catalyzed hydrolysis of esterified HBPEs was investigated systematically. It was found that the increase in the alkane chain length of the end groups diminished the enzymatic degradation of the polymer, whereas the number of end groups had no influence on the degradation rate. The effect of temperature on the rate of degradation was also described. Surface morphological changes that occurred during the degradation were assessed with reflected electron microscopy. The changes in the crystallinity of the polymers after they were subjected to degradation were qualitatively determined with differential scanning calorimetry through the quantification of the enthalpy of melting. The enthalpy of melting of one HBPE sample increased from 79 to 90 and 94 J/g with and without the action of Lipomod 34P, respectively, in 7 days, showing the changes in the crystallinity of the polymer. The results prove that modified HBPEs are an important new class of biodegradable materials with a predictable degradation mechanism, and the degradation can be adjusted on the basis of the molecular engineering.

INTRODUCTIONIn butter, milk, and dried milk, flavour deterioration accompanies a slight degree of oxidation of the butterfat, and for the study of oxidative deterioration of these products a method is required which measures fat oxidation at a very early stage. In this laboratory it has been found that the iodometric peroxide method of Lea(i), although slightly more sensitive than the fat aldehyde test of Schibsted(2), registers measurable values only at about the stage of oxidation of butterfat when flavour changes first appear. The work of Chapman & McFarlane(3) and of Lips et al.W has directed attention to the value of the ferric thiocyanate peroxide test in the study of oxidation of the fat in dairy products, and it was hoped to use this method in studying oxidation before flavour changes could be detected. Difficulties were encountered in the low solubility of fat in 96 % acetone, and in the rapid oxidation of ferrous salts in this solvent. Modifications have been made to the test, and in its final form it has proved sufficiently sensitive to follow the oxidation of the fat of milk from the time it leaves the udder. METHOD Reagents (1) Benzene-methanolThe solvent is a mixture of 70 vol. of benzene and 30 vol. of methanol. A.R. quality benzene is redistilled and the first three 20 ml. lots are used to rinse the receiving vessel. Synthetic methanol is dried by refluxing during 4 hr. with bright magnesium ribbon (5 g./l.), and is then distilled. The moisture content of the mixed solvent should not exceed 0-5%. This may be checked with the Karl Fischer reagent(5).As the benzene-methanol mixture is cheap, its recovery is probably not economical. When necessary it may be recovered by adjusting the acidity with a saturated solution of potassium hydroxide in methanol to give a reading of pH 7 with the glass electrode (to avoid distillation of ammonia or thiocyanic acid), refluxing during 4-5 hr. with 20-mesh anhydrous calcium sulphate, and then distilling. The moisture content of the recovered reagent should be checked and the j?H value determined and adjusted if necessary to between 6-0 and 7-0. The proportion of benzene and methanol may be corrected by adjusting the specific gravity to 0-850 at 20° C.(2) Ferrous chloride solution Hydrated barium chloride (0-4 g.) dissolved in 50 ml. water is added slowly, with stirring, to 0-5 g. hydrated ferrous sulphate dissolved in 50 ml. water, and 2 ml. of 10 N hydrochloric acid is then added. All reagents should be free of ferric iron. The precipitate G. LOFTUS HILLS AND C. C. THIEL 341 of barium sulphate is allowed to settle, and the clear solution is then decanted into a bottle protected from light. The solution is sufficiently stable to be usable for about a week; the extent of oxidation may be judged by noting the colour obtained when 1 drop of 30% ammonium thiocyanate is added to 1 ml. of the ferrous chloride solution. A solution containing one-fifth this concentration of ferrous salt, but the same concentration of hydrochloric acid, should be used for peroxide values b...

An apparatus has been developed for the routine estimation of oxygen in the headspace gas of tins of dried milk. The sampling device is an integral part of the apparatus, which is constructed mainly of metal and is simple to operate. As many as twenty samples may be taken and analysed in an hour.Our thanks are due to the Drawing Office and Workshop staffs of the Division of Industrial Chemistry, Council for Scientific and Industrial Research, who designed and manufactured the equipment, and to the Maffra Co-operative Milk Products Co. Ltd., who permitted the apparatus to be tested in their laboratories under factory conditions.