Christopher Beermann

Detection of antibacterial activity of an enzymatic hydrolysate generated by processing rainbow trout by-products with trout pepsin.

Trout by-product hydrolysates, generated using trout pepsin, were characterized and studied in terms of their antibacterial effects against food contaminants and fish farming pathogens. After a hydrolysis time of 25 min, the hydrolysates demonstrated inhibitory activity against several gram-positive and gram-negative bacteria. The degree of hydrolysis (DH) was found to exert a considerable influence on antibacterial activity, with a significant increase in the observed inhibitory effect at the beginning of hydrolysis. The highest antibacterial activity was obtained at a DH of 30% (enzyme/protein ratio 0.04 U/mg of protein, enzyme activity 6.5 U/mg protein, hydrolysis conditions 37°C, pH 3.0). The highest antibacterial activity detected was against the fish farming bacteria Flavobacterium psychrophilum and Renibacterium salmoninarum, with minimal inhibition concentrations of 2mg/ml and 5mg/ml, respectively. The amino acid determination of the hydrolysate (DH 30%) revealed that lysine, leucine, alanine, arginine, glycine, aspartic acid and glutamic acid residues represented the major amino acids.

Current enzymatic milk fermentation procedures

Aside from bacteria, yeasts and moulds, enzymes from animal, vegetal and microbial sources are increasingly utilized for milk fermentation providing a broad spectrum of innovative product conceptions. In order to alter texture and flavour or to improve the nutritional value of milk-based products from different animal milks, microbial and enzymatic fermentation procedures are traditionally established worldwide. To date, genomic and proteomic approaches enable new selection strategies for precise enzymes for modern product applications. Hereby, generating beneficial health ingredients from milk is a main aspect. New insights into the biochemical mechanisms of enzymatic digestion and genetic engineering lead to enzymes with exact defined functions for explicit ripening flavour development or the improvement of texture of fermented milk products. The ability to synthesize complex exo-polysaccharides or to release bioactive peptides by accurate proteolytic activities of enzymes or to enzymatically cross-link the protein matrix in order to modify the texture characteristics of fermented milk products is a raising facet, especially for specific pharma- or nutraceutical applications. This review aimed at discussing the recent research activities on milk fermentative enzymes, with focus on the broad spectrum of enzyme origins and current aspects of genetic engineering. New approaches on proteolytic, lipolytic, glycolytic as well as milk clotting and protein cross-linking enzymatic activities are examined and associated with possible product applications. From technical prospective, advantages and disadvantages of immobilized enzymes within milk fermentation processes are critically discussed.

Combinations of distinct long-chain polyunsaturated fatty acid species for improved dietary treatment against allergic bronchial asthma

Allergic bronchial asthma is a chronic inflammatory disease of the airways with an increasing incidence in Western societies. Exposure to allergens provokes recurrent attacks of breathlessness, airway hyperreactivity, wheezing, and coughing. For the early phase and milder forms of allergic asthma, dietary supplementation with long-chain polyunsaturated fatty acids (LCPUFA), predominantly fish oil-associated eicosapentaenoic (C20:5 ω-3) and docosahexaenoic acid (C22:6 ω-3), and distinct crop oil-derived fatty acids might provide a sustainable treatment strategy, as discussed in several studies. In addition to immune-controlling prostaglandins, leukotrienes, and thromboxanes, specialized proresolving mediators, such as lipoxins, resolvins, protectins, and maresins, are metabolized from different LCPUFA, which actively resolve inflammation. The aim of this review was to discuss the possible synergistic effects of ω-3 and ω-6 LCPUFA combinations concerning rebuilding fatty acid homeostasis in cellular membranes, modifying eicosanoid metabolic pathways, controlling inflammatory processes by focusing on resolving inflammation in the bronchoalveolar system on the cellular level, and helping to control clinical symptoms in bronchial asthma.