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Synthesis of biodiesel is performed mainly by chemical catalysis, but can also be performed by enzymatic or microbial methods, and these might play an important role in future substitution of petroleum-based diesel. To discover sustainable, economically attractive biotechnological processes for biodiesel synthesis, close cooperation between different disciplines is needed. Currently, lipases are the enzymes of choice for the synthesis of fatty acid esters (FAE) from fats and oils, yielding biodiesel with the methyl esters (FAME) as the most important product. More recently, the direct production of FAE using engineered whole cell microorganism has also been described (MicroDiesel). Current enzymatic processes are still hampered by the high costs of the biocatalyst, but significant progress has recently been made leading to the first industrial enzymatic biodiesel production. Enzymatic biodiesel production is mostly attractive because of the starting materials (waste frying oils, oils with high water content, etc.), for which conventional chemical interesterification can hardly be applied.

In this review, the occurrence, properties, nutritional importance and especially biotechnological methods for the production of conjugated linoleic acids (CLA) and CLA-rich lipids are summarized. Beside information from medical and nutritional studies on the biological activity of CLA, the focus is on the enzymatic synthesis of structured lipids containing CLA and the microbial synthesis of CLA.

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Protein recoveries from potato juice by ultrafiltration, polyelectrolyte-coagulation and cryoconcentration were compared. The best yield was obtained by ultrafiltration. Depending on the method of potato juice concentration, differences were observed in: foaming and emulsifying properties, wettability, swelling, and buffer capacity of preparations. The dried preparations contained a high level of proteolytic enzymes inhibitors and glucoalkaloids. Thermal inactivation of preparations before drying led to 43-48% destruction of protease inhibitors and 8 l-&9% glycoalkaloids. At the same time it was observed that thermal treatment led to distinct changes in the amino acid composition of the proteins and had an adverse effect on the properties of the dried preparations.

The paper presents the results of investigations into the technological possibilities of controlling the transgalactosylation process of lactose in permeate after whey ultrafiltration in order to improve the efficiency of galactooligosaccharides or lactulose synthesis. The synthesis efficiency was influenced by the selection of a β-galactosidase preparation, substrate concentration and, in the synthesis of lactulose, also by the ratio of lactose and fructose added to the reaction mixture. The obtained synthesis efficiency of GOS and, most of all, of lactulose (65 g L−1), may be found satisfactory. The study also resulted in a proposed GOS or lactulose concentrates (concentrated or dried) production technology using permeate after ultrafiltration of milk or whey as lactose sources.

Lactic acid bacteria were subjected to screening for the ability of the analyzed strains to synthesize surface-active compounds. The most favorable synthesis of biosurfactants was observed in the culture of Lactobacillus casei 8/4, thus this strain was applied in the subsequent stages of the study. The research enabled determining the optimal conditions of biosurfactants synthesis, which was shown to be mainly determined by the composition of the culture medium and growth phase of L. casei 8/4. Aqueous solutions of biosurfactant preparations displayed antimicrobial activity against the test pathogenic species: Staphylococcus aureus 11, Bacillus subtilis T91, and Micrococcus roseus R2. Analyses conducted with the FTIR demonstrated that biosurfactants were constituted by protein fractions and polysaccharide fractions, i.e. possessed the structure typical of glycoproteins, which is affected by medium composition and the phase of growth of the biosurfactants-synthesizing strain. The same factors determine the structure of proteins in glycoproteins, which was confirmed after electrophoretic separation with the NuPAGE method.

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