INTRODUCTION
Cephalopod mollusks make up a massive group of sea bioresources broadly spread in the world ocean [1]. A short life cycle and quick growth of cephalopod mollusks, as well as their ability to form compact clusters determine a high level of their commercial harvesting [2, 3].
Cephalopod mollusks are easily processable, allowing for the use of various processing methods and a wide range of products, including fermented ones [4-11].
The main commercial species of cephalopod mollusks in the Far Eastern seas are octopuses (Octopus dofleni) and the Commander (Berryteuthis magister) and Pacific (Todarodes pacificus) squids [12]. Annual squid catches are at least 240 000 t, and those of octopuses, 800 000-900 000 t. Despite these solid catches, the current highly processed goods of cephalopod mollusks are produced in amounts insufficient for the country's population. In the consumer market, they are represented mainly by fresh frozen products. In small amounts, cephalopod mollusks are processed into dried, seasoned, and culinary products and preserves, filled with various sauces, but these products have limited storage life and conditions, causing difficulties in their transportation and marketing. The annual output of canned squids is no more than 1.6 million standard cans, and canned octopuses are not produced domestically.
At the same time, the nutritive tissues of cephalopod mollusks are characterized by high organoleptic properties, the presence of complete proteins, and insignificant amount of lipids, as well as a complex of mineral substances [13-20].
Various biologically active substances, including those that are rarely found in terrestrial animals and plants [21-27], have been found in the tissues of cephalopod mollusks; therefore, cephalopod-based products are very useful for various groups of the population and are recommended by nutritionists as ingredients of many diets. In recent decades, biologically active food additives and enzymatic preparations have been developed on the basis of cephalopod mollusks [28-31].
One of the reasons for the low use of raw materials from cephalopod mollusks in canning is the low yield of end products due to high losses of their nutritive part during processing, which makes them unprofitable as canned food under current conditions. The loss of raw materials during canning is explained by the fact that the traditional cephalopod canning technologies require thermal, enzymatic, or mechanical removal of skin integuments from the heads, pallia, and tentacles of cephalopods. At the same time, the skin of cephalopod mollusks belongs to nutritive tissues, containing amino acids, such as proline and oxyproline, which are collagen components [14, 32]. China has developed a technology of producing collagen from the cephalopod skin left after the core production [33]. The preservation of cephalopod skin integuments during canning would increase the utilization factor of this valuable raw material and its end-product yield.
Another important factor of the low motivation of producers in cephalopod canning is the worsening of organoleptic characteristics of the product after sterilization due to the interaction of reducing sugars with amino acids during thermal conditioning (the Maillard reaction) and the formation of melanoidins. As is known, melanoidin formation leads to the browning of sterilized mollusk meat, the appearance of a caramelization smell, and the loss of its inherent flavor characteristics [34, 35]. A decreased thermal effect on the product during sterilization makes it possible to reduce the activity of the Maillard reaction and improve the quality of canned goods.
The goal of this study was to justify and develop new technological approaches to cephalopod canning that reduce raw-material losses and ensure the high quality of end products.
