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Significant amounts of free D-amino acids (D-AA) have been found in fermented foods. Amino acids (AA) were extracted from sour milk, Emmentaler cheese, lactic acid fermented juices of carrots and celery, beer, wine, fermented black beans and a commercial liquid spice obtained by acidic hydrolysis of certain proteinaceous plants. The absolute amounts of free AA in foods were determined by automated ion-exchange chromatography according to Stein and Moore, and the ratios of AA enantiomers were determined as theirN(O)-pentafluoroproprionyl 1- (and 2-) propyl esters by capillary gas chromatography on the chiral stationary phases Chirasil-L-Val and XE-60-L-Val-(S)-α-phenylethylamide. Since D-AA were found in all fermented foods investigated and also on the basis of biochemical considerations of the orgin of D-AA in microorganisms, it may be assumed that D-AA are quite common in fermented foods.

Lipopolymers comprised of an N-isopropyl acrylamide backbone modified with lipid side chains and a disulfide moiety can be used for the preparation of thin films by chemisorption from solution and by LB-transfer as well. The resulting thin polymer layers were characterized using surface plasmon resonance, contact angle measurements, and grazing incidence FTIR spectroscopy. With both methods thin polymer films of a comparable thickness can be prepared (about 20 Å). But while chemisorption is the easier technique, LB-transfer has the advantage that a transfer at different surface areas allows an additional variation of the film thickness and the contact angle.