The results of a study of the chemical composition and functional properties of the plant raw material in the form of wheat germ flakes (WGFs) with a view to combining it with a meat feedstock are represented. WGFs subjected to preliminary heat treatment in various modes (toasted) are studied. It is found that water-soluble and salt-soluble proteins of WGFs exhibit high solubility, which achieves maximum values of 45 ± 2% at a pH of 7.08.0 and a sodium chloride concentration of 2.0%. The functional properties of WGFs and dependences of the functional and technological properties of combined ground meat systems prepared of meat feedstocks of different types and nature of autolysis are determined. A preliminary heat treatment of WGFs does not decrease their functional properties, which are particularly shown in feedstock with anomalies in the development of autolysis, and contributes to a decrease in the oxidative transformation of lipids. In combined ground meat systems, toasted WGFs should be used in conjunction with 0.3% of a Delikaroma smoking flavor; this inhibits the oxidation of the lipid fraction of both raw and heat-treated ground meat systems.
meat, wheat germ, lipid fraction, toasting, oxidation inhibition
INTRODUCTION
Meat products are traditional gastronomically valuable foods that have a long history of consumption. This is the main source of proteins with a high nutritional value, which have a significant effect on the protein metabolism of the human body. According to the modern concepts of nutritional science, the fraction of proteins should be 1015% of dietary calories and animal proteins should be 50-60% of daily protein requirements. According to the data of the Institute of Nutrition of the Russian Academy of Medical Sciences (RAMS), the recommended intake of meat products depending on the age group of the population is 143 g/day (1829 and 3044 years old), 124 g/day (4559 years old), and 85 g/day for people aged 60 years and over.
Analysis of the actual diet of Russians in recent years has revealed a number of positive tendencies in changing its structure and qualitative composition. The per capita consumption of biologically valuable foods, such as meat and meat products, milk and dairy products, eggs, and fish, has significantly increased, although it is still below the standard. A consequence of this is the lack of an animal protein (33%) at a total protein deficiency in human nutrition (at a level of 26%). These data provide a significant ground for the development of scientifically based ways of correcting the diet of the population. However, it should be remembered that an increase in the consumption of animal food is associated with an increased consumption of animal fats, which contain high amounts of saturated fatty acids.
Therefore, the modern concept of formulation of meat products involves not only an expansion of the product range and an increase in the volume of their production, but also the solution of a number of important problems, among which a particular position is held by the development of a technology for products meant for improving the nation's health and furthering the safety of products.
Scientists and experts in the implementation of this direction should pay particular attention to plant raw materials because the possibilities and prospects for the use of these materials are extremely broad. Cultivated and wild plant raw materials may be used as a basic ingredient or flavoring and aromatic components in the manufacture of general-purpose products, custom-designed food stuff, dietary supplements, and supplements exhibiting antioxidant and antimicrobial activity. Plant raw materials can be used to solve the problem of reducing the calorie intake with the compensation for the reduction of fat intake by carbohydrates, including complex carbohydrates, and replacing saturated fats with polyunsaturated fatty acids of plant raw materials.
Plant raw materials with a high content of proteins are of great importance in the meat product technology; the significance of proteins is determined not only by their nutritional value, but also by the involvement in the formation of the basic functional and technological characteristics of the feedstock and, consequently, the consumer properties of the products.
Analysis of scientific and engineering information shows an expansion of research into various types of plant raw materials as an alternative to traditionally used soybeans. Fairly well-known promising plants for producing flour and isolated and concentrated forms of proteins are lentils, chickpeas, peas, beans [14]. By-products of grain processing, in particular, wheat and rice bran, have a high technological potential [5, 6]. A high-protein feedstock for producing isolates and concentrates are nuts, such as peanuts, which contain 21% to 36% protein [7, 8], almonds containing about 33% protein [9, 10], and walnut [11]. Along with nuts, the researchers study seeds, extraction cakes, and press cakes of other oil-bearing crops, such as rape and flax; the protein content in press cakes of the last-mentioned plants is up to 54% [12, 13]. It should be noted that there is a keen interest in some plant species, in particular amaranth, a commercial use of which is possible in the near future [14]. These data suggest that the use of plant raw materials in food technology have broad possibilities; the combining of these materials with an animal feedstock for manufacturing products with a complex feedstock composition is a common practice in the world.
Wheat germ is of obvious interest in terms of nutritional value and the possibility of using it in the meat product technology. Despite small sizes of the germ (2.03.0% with respect to the mass of the grain), it is the most important part of the grain because it contains the primary organs of development of the plant, and this is responsible for its unique chemical composition. Wheat germ contains a large number of biologically active components; its protein is close to the physiologically active proteins of animal tissues and more fully-featured and balanced with respect to amino acid composition than the grain protein in general. This is attributed to the fact that gluten proteins, which are classified as reserve proteins, are mostly contained in whole grains, while biologically active proteins are dominant in the germ [1518].
Wheat germ remains insufficiently demanded in the meat product technology because of scarce data on its technological capabilities and the pattern of interaction with components of the feedstock to be enriched in it.
A study of the fractional composition of the protein complex of wheat germ will make it possible to determine its affinity to muscle salt- and water-soluble proteins that are involved in the formation of stable meat systems and find the fraction of gluten proteins that can form a complex that stabilizes the product structure directly in meat systems.
Of great importance from the standpoint of safety and nutritional value of food products is the stability of their lipid component. According to the best available data, wheat germ contains phenolic components exhibiting antioxidant activity, including ubiquinone coenzymes and vitamins E [19]; at the same time, it contains prooxidant factors against the background of a high content of polyunsaturated fatty acids [20, 21]. It should be taken into account that the oxidation of lipids in the composition of meat products takes place under special conditions, which are primarily associated with the presence of heme pigments. Research into the redox potential of heme components has proved that coordinated iron of heme pigments is ideally suited for the role of an oxidation catalyst for fatty acids owing to the presence of unpaired electrons in their structure. Heme pigments are oxidized by hydroperoxides; this process is accompanied by a change in the valence of iron from Fe2+ to Fe3+; the resulting free radicals are involved in a variety of oxidation chain branching reactions [22].
Thermal action methods are efficient for the stabilization of wheat germ lipids; according to the best available data, these methods do not cause a significant change in the fatty acid profile and a decrease in the activity of phenolic antioxidants [23]. In addition, it is possible to improve their hygienic quality, particularly owing to a decrease in the activity of anti-nutritional factors, such as trypsin inhibitors [24, 25] and microbial contamination. Therefore, in this study, along with native wheat germ flakes (WGFs), previously toasted WGFs were analyzed. Heat pretreatment is also aimed at imparting improved organoleptic properties, particularly flavor and smell, to the germ. At the same time, heat pretreatment can also result in a change in the functional properties of wheat germ owing to a change in the protein and carbohydrate components and initiate the oxidation of labile lipids under complicated conditions of meat systems.
The aim of this study was to examine the chemical composition and functional and technological properties of wheat germ depending on the pretreatment method and its effect on the technological properties of ground meat systems prepared of feedstocks of different types and nature of autolysis and the stability of the lipid fraction of the systems in order to substantiate its use in the cooked sausage technology.
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