1. Improving, intensifying and optimizing the ripening process of fish meat during marinating and salting, in terms of:

•         Diffusion (loss) of nitrogenous substances from the meat into the marinating brine,
•         Influence of technological factors on the ripening process: primary processing, method of preservation the raw material, composition of the brine, process temperature, type of cover-brine,
•         Influence of selected substances on the ripening process of meat: type of salt and acid, addition of sweeteners, addition of preservatives, addition of protease inhibitors,
•         Influence of biological factors on the ripening process: herring species, herring fishing season,
•         Nitrogen indicators of the quality of marinated, salted and fresh fish.

1.     Occurrence of cathepsins in the marinating brine, consisting of:

•         The proportion of aspartyl proteases,
•         Activity of cathepsins in the free fraction and in lysosomes,
•         The influence of biological and technological factors on the diffusion of cathepsins,
•         Recovery, purification and technological characterization of cathepsin preparations.

1.     Reuse of brine with active cathepsins in the process of marinating marine and freshwater fish.
2.     Improving test methods for the isolation and determination of cathepsin activity.
3.     Use of digestive proteases to improve the ripening of marinated meat.
4.     Application of isoelectric protein precipitation technique in fish processing.
5.     Preservation of peeled meat shrimp and management of shell.
6.     Use of surimi from fish to obtain aquatic foods.
7.     Recovery of valuable compounds from co-products in the fish industry, production of hydrolysates, and subsequent enrichment of foods with bioactive components (e.g., biopeptides) of fish origin.
8.     Shelf life of raw materials and fish products, changes in raw fish during refrigerated and freezer storage.
9.     The use of food additives in the food industry.