Theory and practice of meat processing

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Vol 6, No 3 (2021)
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200-209 200

 The development of sustainable feed ingredients for monogastric livestock is nowadays considering insect meals and oils to replace or supplement conventional feedstuffs. Although the regulation on the use of insect products differs among  countries resulting in restrictions on use in the diets of  monogastric meat producers, global research is exploring all the  strengths and weaknesses of their inclusion. Therefore, whereas  the scientific literature has extensively studied both the  relationship between insect farming systems and safety (potential health risks), and between the dietary use of insects  and the nutritional value of diets and production performance of farm animals (fish, poultry, swine, rabbit), the relationship  between insect-containing diet and meat quality has only recently been considered. The present review therefore aims to  collect the results of the studies that have related the dietary use of some insect species, such as the black soldier fly (Hermetia  illucens), the yellow mealworm (Tenebrio molitor) and the silkworm (Bombyx mori), on the physicochemical and sensory  traits of the poultry, swine and rabbit meat. The variable that has been most affected by the inclusion of insects as feed on  livestock meat quality is the fatty acid (FA) profile, which, as is well known, in monogastrics tends to reflect that of the diet.  Therefore, the black soldier fly inclusion has always originated meats with a more saturated FA profile, the yellow mealworm a  more monounsaturated fatty acid profile, whereas the silkworm a more unsaturated fatty acid profile and rich of valuable  omega-3 FA, but rarely changed the related physicochemical  variables, or the sensory profile of the meat. 

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By-products are the potential source of animal protein obtained from brood chickens and egg-laying hens. Certain by-products like gizzards and combs are quite tough and possess low nutritional and biological value due to their high content of connective tissue. Biotechnological processing improves the quality parameters of collagen-containing by-products. In this article a probiotic starter culture of propionic acid bacteria, which have high proteolytic activity, was used to treat the gizzards and combs of brood chickens. Before processing of by-products with starter culture, physical and chemical parameters and the yield of by-products in relation to poultry live weight were analyzed and recorded. 5%, 10% and 15% starter culture were added to the tested samples of chopped by-products, the samples were kept at a temperature of 30 °C, and every 4 hours the following functional and technological parameters were monitored: moisture binding capacity, water holding capacity (MBC and WHC) and yield of the product after heat treatment. The results proved that increase of starter culture amount and longer exposure of by-products to hydrolysis led to decrease of functional and technological parameters values, but for the combs those parameters remained at a sufficiently high level compared to the gizzards, as the gizzards were exposed to more intense hydrolysis than combs. The decrease in the pH value correlated with the dynamics of MBC and WHC changes; and dynamics of the product yield after the heat treatment. Also the stained histological preparations were studied in order to assess the influence of biotechnological processing on by-products microstructure, where significant differences were found in the morphological structure of muscle and collagen fibers of hydrolysates of combs and gizzards exposed to action of bacterial concentrate. The results of rheological studies showed that hydrolyzed chicken combs differed from gizzards; the combs were denser and featured more elastic structure due to a lower degree of hydrolysis by bacterial enzymes. In general, the properties of collagen-containing by-products (muscular gizzards and combs) change significantly after being exposed to enzymes of propionic acid bacteria.

219-225 57

The aim of this study was to provide a quantitative exposure assessment to essential elements through the consumption of canned fish in Serbia. This objective was fulfilled by analyzing content of essential elements in canned fish and by using data from a food consumption survey. Consumption survey of canned fish was designed and performed to general principles and EFSA guidelines on data collection of national food consumption. The questionnaire was performed on 1,000 respondents during 2018. Determination of copper, zinc and iron levels were performed on 454 canned fish and seafood samples divided into four groups (canned tuna, canned sardines, canned other sea fish and canned seafood) during five consecutive years (2014–2018). This study showed significant association between sex, BMI and weight and consumption patterns. Obtained average weekly consumption of canned fish confirms our assumption that consumption of canned fish is significant in Serbia. Zinc and iron were found in all 454 samples (100%), and copper in 222 samples (48.9%). The average obtained concentration in all samples were 1.268 mg kg–1 for Cu, 5.661 mg kg–1 for Zn and 9.556 mg kg–1 for Fe. The highest concentration for all three minerals were found in canned sardines (Cu — 6.49 mg kg–1, Zn — 37.2 mg kg–1 and Fe — 21.8 mg kg–1). Obtained mean exposure to intake of copper, zinc and iron from canned fish was 1.2241 μg/kg bw/day, 5.4634 μg/kg bw/day and 9.2231 μg/kg bw/day, respectively. Exposure of Serbian population to zinc, copper, and iron through consumption of canned fish is less than recommended daily reference intakes and there is no risk of reaching toxic levels by consuming fish.

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Technologies of isolation and concentration of biologically active substances, developed in the middle of the 20th century, need adjustment and adaptation to modern conditions both to increase the activity of substances and for greater economic efficiency. The aim of the research is the comparison of dynamics of biologically active compounds extraction from porcines pancreas in two methods: the saline method based on 0.9% sodium chloride solution, and the acidic method based on 2.4% trichloroacetic acid solution. Also the purpose of research is to assess the possibilities for further optimization of technologies. The total protein concentration based on the biuret reaction in the samples taken during the extraction, as well as the calculation and analysis of the point degrees and rates of extraction are chosen as the controlled parameters. Local maxima of the protein yields into the extractant media at the 60th, 135th and 255th minute were recorded during saline extraction; and at the 75th and 135th minute during acid extraction. Also the proteomic profile of the extracts was studied. Wide range of compounds with molecular weight of less than 52 kDa was found in extracts based on physiological saline solution, and protein substances of whole presented range of molecular weights in trichloroacetic acid based extracts were considered. The predominance of low molecular weight protein fraction of interest was noted also in this method of extraction in comparison with the other methods of extraction. According to the UniProt database, we assume availability of probable compounds with a molecular weight of less than 30 kDa in the purified acidic extract. The presence of some proteins absent in the final saline extract was noted. The acidic erythrograms showed a weak degrading effect of both types of extracts on the membranes of rat erythrocytes, as well as the cytoprotective effect of acidic ultrafiltrates (less than 3 kDa). The obtained results prove a better efficiency of trichloroacetic acid extraction method used for obtaining a mixture of a wide range of compounds, including biologically active substances of low molecular weight.

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In the presented article the authors consider the issues of development of regression model for process of food digestion by proteolytic enzymes in human body. The authors use correlation analysis. They analyze the main nutritional values and physical and chemical properties of meat products, the modes of heat treatment of semi-finished lamb products. The essential parameters and features are determined to find the dependence between the factor values and efficient values of the basic raw material, which affect the quality of the technological processes and, in general, the finished product. The regression model equation is mathematically calculated by methods of solving K. Gauss linear equations. The standard deviations of parameters are calculated, the initial data are normalized; the matrices of the pair correlation coefficients, lower and upper limits of their values are compiled. Equations of the mathematical regression model of meat proteins attackability by proteolytic enzymes — in vitro (pepsin, trypsin) are developed. It is proved that the obtained equation represents a regression model of the process of meat food proteins attackability by enzymes (pepsin, trypsin and chymotrypsin), depending on the determined 3 essential factors (weight of a meat piece, duration of frying, collagen content in lamb meat). Also this equation reflects the process of lamb digestibility in a digestive tract of a human body.

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This paper presents an overview of the meat supply chain in the perspective of main UN sustainable development goals (SDGs). To perform this overview, meat supply chain was presented with five main stakeholders (livestock farmers, slaughterhouses, meat processors, retailers and consumers). As this chain is specific, four SDGs have been revealed as most important, as follows: SDG6 — Clean water and sanitation; SDG7 — Affordable and clean energy; SDG12 — Sustainable consumption and production; SDG13 — Climate action. Discussion and literature review was performed for each of the four UN SDGs. In addition, other UN SDGs of interest for this supply chain have been briefly presented.

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The paper presents the results of the investigation of the overall chemical composition (mass fraction of moisture, fat, protein and ash) and the amino acid composition of mutton from the experimental animals of new genotypes: Sovetsky Merino x Dzhalginsky Merino and Sovetsky Merino x Stavropolsky breed. As a control, meat of purebred Sovetsky Merino was studied. The experimental and control rams were slaughtered at the age of 8 months by the conventional technology. Meat samples for laboratory examination were taken a day after slaughter. The results of the analysis of the overall chemical composition showed that lamb meat of new genotypes had lower moisture content and higher content of fat and protein compared to the control. Analysis of the amino acid composition of meat proteins of genotypes Sovetsky Merino x Dzhalginsky Merino and Sovetsky Merino x Stavropolsky breed revealed lower content of essential amino acids compared to the control. Comparison of amino acid scores showed that the amino acid composition of meat proteins from the experimental animals was limited by valine and lysine, respectively. It was concluded by the results of the investigations of the amino acid composition of proteins that the biological full value of proteins of mutton from new genotypes was 22.9% and 30.3% lower than that of the control.

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Meat from rabbits offers high nutritive properties as it has high levels of essential amino acids, minerals and vitamins. Rabbit meat is also regarded lean, since it contains less fat than many other meat types. The composition of rabbit meat lipids is also favourable due to higher contents of unsaturated fatty acids compared to other types of meat. The aim of the present study was to examine and compare meat quality from male and female rabbits. A total of 24 rabbits (12 males and 12 females) were used. The rabbits were slaughtered at an age of 17–18 weeks. The following parameters were studied: slaughter traits, colour, pH, cooking loss, tenderness, total fat content and water holding capacity (WHC). Interestingly, the ultimate pH was significantly lower in male compared to female rabbits (p = 0.008). Moreover, cooking losses were higher in the meat from male rabbits (p = 0.001). No other relevant differences were found between meat from male and female rabbits suggesting that sex might be regarded as a minor factor in the production of rabbit meat at the chosen slaughter age.

259-268 78

The paper presents a review of available data about an effect of food additives on the human microbiome and lists the main physiological functions of the gut microbiome. The process of the human microbiome evolution is examined. The relationship between the emergence of a disease and the microbiome composition, as well as the main factors influencing the gut microbiome composition are described. The main food additives used today are listed, their key features are discussed and their structural formulas are given. The information about their effect on the human body through an influence on the microbiome composition is presented. The data on an effect of polysorbate 80, carboxymethylcellulose, sodium sulfite, nisin, potassium sorbate, sodium benzoate, sodium nitrate, essential oils, titanium dioxide and different sweeteners on the microbiome are analyzed. It is explained what microbial communities are suppressed and what communities gain advantages in multiplication when consumers eat food with one or another food additive. The consequences of alterations in the microbiome for the consumer’s body are examined. Conclusions were made about the necessity of additional studies about an effect of food additives on the composition of the human microbiome.

269-278 76

The available scientific literature, domestic and international regulatory codes of normative documents concerning the fortification of various types of food products have been analyzed. The groups of food products of conventional and regular consumption included into the diets of all categories of consumers, recommended for fortification with essential micronutrients, have been determined: wheat and cereal flour (spelt wheat, buckwheat, oat, corn flour, etc.); pastry; milk and dairy products, including ice cream; non-alcoholic soft drinks; mineralized drinking water; fruit and vegetable juices; fat and oil products (vegetable oils, margarines, spreads, mayonnaise); confectionery and sweets (pastry, sugar, chocolate); cereals (breakfast cereals, muesli, ready-to-eat extruded cereals, instant pasta and cereals, mixtures for bakery, flour for sweet pastry); food concentrates (jelly, instant drinks, concentrates of sweet foods, instant food, instant cereal concentrates); table salt. The groups of food products assigned for certain categories of population are used as part of therapeutic diets for patients with various diseases (metabolic disorder syndrome, cardio-vascular system pathology with atherosclerotic vascular injury, type 2 diabetes mellitus, gastrointestinal tract diseases, non-alcoholic fatty liver disease, diabetic nephropathy, etc.), as well as assigned to reduce the risk of diseases developing, the nutrients are recommended for targeted fortification of certain types of food. Examples of micronutrients fortification of sausages and minced meat semifinished products are given below. Requirements for fortification of mass consumption food products and for fortification of foods for special dietary uses are formulated in this article, the amount of fortifying components in the various groups of food products are justified, ensuring their efficiency for improving the micronutrient status and safety of its consumption. Based on the analysis of the available scientific literature, domestic and international regulatory framework of normative documents on fortification of various types of food products, recommendations have been developed for fortification of food with micronutrients.

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Bone gelatin is an important and irreplaceable item widely used in the food industry and pharmaceutical production; it is also widely used in tissue engineering and other spheres. Due to widespread use of gelatin it is necessary to search for new safe and effective technologies for bone gelatin production. This research represents the results of enzymatic-acid hydrolysis of raw material in the process of gelatin production. The article presents the results of hydrolysis analyzes, the results of the main quality parameters of the obtained gelatin samples; and the major technological scheme for gelatin production is proposed here. As result of developed technology of enzymatic-acid hydrolysis of bone raw material with the ratio of raw material mass to the volume of solvent (HCl 1M and pepsin with an enzymatic activity of 40 units) as 1:9, duration of exposure: 180 minutes (3 hours), at the stage of demineralization, liming and de-ashing, we obtained samples of gelatin at yield rate of 12.1% from the initial mass of raw materials, which is 6.9% higher in comparison with the lowest yield of gelatin according to the proposed schemes. It is shown that the samples have a high protein mass fraction 91.4%, and a low fat mass fraction 0.4%, the obtained results indicate the high technological qualities of the obtained gelatin sample, this is also confirmed by high strength of gel according to Bloom scale, which value varies within the range of 290 ± 0.7 units.

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Thermal conductivity factor and specific isobaric heat capacity of food products are currently the most important parameters in the development of mathematical models for food freezing and thawing and in improving production technology. There is significant variance among the existing experimental data for the thermal conductivity factor in meat. Most of the modern calculated relationships are based on the nutritional approach, which favorably differs by the ability to calculate the thermophysical characteristics of any food products. However, the calculation error at the subcryoscopic temperatures may be 15% to 20%. The development of superchilling as a way of storing meat requires high accuracy of freezing time calculation, including vacuumpacked boneless meat. In the presented article, the authors investigated hydrogen index, cryoscopic temperature, frozen moisture proportion and thermal conductivity factor for beef M. longissimus dorsi samples of NOR and DFD grades. It was found that DFD beef is characterized by 10% to 12% higher values of thermal conductivity factor in comparison with NOR grade. Using the method of regression analysis, the authors developed empirical relationships for calculating the thermal conductivity factor of meat depending on its temperature and pH level. Unlike cryoscopic temperature and frozen moisture proportion, pH is easy to measure and may be easily used on a conveyor belt for more accurate assessment of meat thermophysical properties. With an increase in pH from 5.3 to 7, an increase in cryoscopic temperature is observed from minus 0.94 °C to minus 0.72 °C. It has been shown that one of the factors for the higher cryoscopic temperature and higher pH level of DFD beef is higher water-holding capacity with less strongly bound moisture.

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