Insect-based proteins in meat products: Evaluating the functional properties of Locusta migratoria

Despite the existence of an AOAC official method based on an enzyme-linked immunosorbent assay (ELISA) for the determination of additions of soybean proteins in meat products, its use for quantitative assessment is limited. Accordingly, a simple and inexpensive method has been developed and validated in this work. The method involves defatting the meat samples with acetone, solubilization of soybean proteins in a 30 mM Tris-HCl buffer (pH 8) containing 0.5% (v/v) 2-mercaptoethanol, and the identification of two peaks from soybean proteins in the chromatogram obtained by perfusion reversed-phase chromatography and UV detection. Determination of soybean proteins by the proposed method did not suffer from matrix interferences, with a good linear correlation up to a concentration of 12.50 mg/mL soybean proteins being observed. The proposed method was proven to be specific, precise, accurate, robust, and sensitive, making possible the detection and the quantitation of additions of 0.07% (w/w) and 0.25% (w/w), respectively, of soybean proteins in meat products (related to 1 g of initial product). The method has been applied to the determination of the soybean protein content in commercial heat-processed meat products, obtaining results that were statistically similar to those obtained by the official ELISA method but with a higher reliability and simplicity and a lower cost and analysis time.

Use of vegetable proteins in meat products in Denmark is discussed with special reference to economy. Aspects of price vs. quality also are discussed, and performance criteria in the evaluation of vegetable protein products are proposed. Examples are given of recipe optimization with soy protein products, and finally the market perspectives are outlined. It is emphasized that no conflict is seen between the use of vegetable proteins in meat products and agricultural or consumer interests.

In recent years, various protein additives intended for manufacture of meat products have increasing importance in the food industry. These ingredients include both, plant-origin as well as animal-origin proteins. Among animal proteins, blood plasma, milk protein or collagen are used most commonly. Collagen is obtained from pork, beef, and poultry or fish skin. Collagen does not contain all the essential amino acids, thus it is not a full protein in terms of essential amino acids supply for one's organism. However, it is rather rich in amino acids of glycine, hydroxyproline and proline which are almost absent in other proteins and their synthesis is very energy intensive. Collagen, which is added to the soft and small meat products in the form of isolated porcine protein, significantly affects the organoleptic properties of these products. This work focused on detection of isolated porcine protein in model meat products where detection of isolated porcine protein was verified by histological staining and light microscopy. Seven model meat products from poultry meat and 7 model meat products from beef and pork in the ratio of 1:1, which contained 2.5% concentration of various commercially produced isolated porcine proteins, were examined. These model meat products were histologically processed by means of cryosections and stained with hematoxylin-eosin staining, toluidine blue staining and Calleja. For the validation phase, Calleja was utilized. To determine the sensitivity and specificity, five model meat products containing the addition of isolated porcine protein and five model meat products free of it were used. The sensitivity was determined for isolated porcine protein at 1.00 and specificity was determined at 1.00. The detection limit of the method was at the level of 0.001% addition. Repeatability of the method was carried out using products with addition as well as without addition of isolated porcine protein and detection was repeated 10 times. Repeatability in both, positive and negative samples, for isolated porcine protein was determined at 100%. The results show that the histological processing of cryosections stained using Calleja is suitable for detecting isolated porcine protein in meat products.

SummaryA method based on laser densitometry of polyacrylamide electrophoretograms of proteins extractable in 10 m urea is described for the quantitative identification of soya protein in fresh meat products and in those heat processed at 100°C for over 1 hr. Qualitative identification of soya protein remains possible in products heated to the level of commercial sterility (127°C for 24 min). It is suggested that the method could also be used for the assessment of other non‐meat proteins in meat products.

In food industry nowadays, there are various plant-origin protein additives which are meant for production of meat products. Among the most frequent additives of this type there are different kinds of flour, starch, fiber, and plant-origin proteins. Their usage at present is limited by the existing legislation not to prevent consumer deception but also for reasons of possible influence on consumer health. Therefore, this problem is paid a lot of attention not only in the Czech Republic but also all over the world. The main risk is seen in the impossibility to choose a suitable foodstuff for an individual prone to allergic reactions. Potential allergens are also often plant-origin raw materials which are added into foodstuffs for their technological qualities and low price. Wheat is widely cultivated cereal as well as an important source of proteins. After ingestion or inhalation, wheat proteins may cause adverse reactions. These adverse effects include a wide range of disorders which are dependent on the method of contact with wheat protein. These adverse effects can then take the form of various clinical manifestations, such as celiac disease, T-cell mediated inflammatory bowel disease, dermatitis, skin rash, breathing difficulties, allergy to pollen or to wheat flour or food allergy to foodstuffs containing gluten. The only possible protection against adverse immune reactions for those with food allergies is strictly excluding the allergen from their diet. Although the number of studies dealing with the reduction or loss of allergenicity is increasing, yet these practices are not common. Most of the population suffering from food allergies is thus still dependent on strict exclusion of foodstuffs causing adverse allergic reactions from their diet. In order to avoid misleading consumers and also to protect allergic consumers, analytical methods applicable to all types of foodstuffs have been developed. Unfortunately, detection of allergens in foodstuffs is relatively difficult because of the fact that they occur in trace amounts and are often masked by various parts of the product. This paper deals with detection of wheat protein in meat products bought in the retail network of the Czech Republic. Ten cooked meat products, especially types of sausages and soft salami which stated wheat protein in their composition, were examined. The samples were processed using the method of immunofluorescence and stained with Texas Red fluorochrome. The presence of wheat protein was demonstrated in all the examined meat products. From the results it follows that the method of immunofluorescence is suitable for detection of wheat protein in meat products.

Nowadays there are various vegetable protein additives intended for the manufacture of meat products in the food industry. These ingredients include both, plant-origin as well as animal-origin proteins. The most common vegetable additives include various types of flour, starch, fiber and plant protein. Among animal proteins, the most commonly used are plasma, collagen or milk protein. Milk protein is added to meat products due to its functional properties, such as emulsifying fats, improving the holding capacity of meat, improving juiciness, gel-forming capacity and affecting the taste of the product. Usage of these proteins, however, is currently limited by the effective legislation, not only in order to prevent consumer deception, but also because of their potential impact on consumers' health of. Thus, this issue has received considerable attention not only in the Czech Republic, but also globally. The main risk is the impossibility of selecting a suitable foodstuff for individuals with potential allergic reactions. The only option for allergic consumers to protect themselves is to strictly exclude the given allergen from their diet. Although the number of studies dealing with the reduction or loss of allergenicity is increasing, yet these practices are not common. Most of the population suffering from food allergies is thus still dependent on strict exclusion of foodstuffs causing adverse allergic reactions from their diet. Detection of allergens in foodstuffs is unfortunately quite difficult due to the fact that they occur in trace amounts and are often masked by different parts of the foodstuff. This research dealt with the detection of milk protein in meat products purchased in the market network of the Czech Republic, whereas declaration given by the manufacturer on the packaging for the small meat products purchased from the market was used to verify the detection of milk protein by the immunofluorescence method. 20 products were examined, these were selected with regard to the presence of milk protein that was declared by the manufacturer on the packaging. Method validation was performed by comparing the positive results from the investigated method with information on the packaging of the meat product. Milk protein was detected in 84.62 per cent of samples where the manufacturer declared the presence of milk or cheese on the package and additionally in 85.71 per cent of samples where the manufacturer declared the presence of milk protein. The results show that the immunofluorescence method is suitable for the detection of milk protein in meat products.

Dr. Lourdes Amigo, Instituto de Fermentaciones, Industriales (CSIC), Juan de la Cierva, 3, 28006 Madrid, SpainThe use of soyabean proteins as meat extenders has spread significantly due to the interesting nutritional and functional properties that are present in soyabean proteins. Together with these, health and economical reasons are the major causes for the addition of soyabean proteins to meat products. Nevertheless, despite the good properties associated to soyabean proteins, there are many countries in which the addition of these proteins is forbidden or in which the addition of soyabean proteins is allowed up to a certain extent. Thus, the need of analytical methods enabling the detection of added soyabean proteins in meat products is obvious. Microscopic, electrophoretic, immunologic, and chromatographic methods are the most widely used for this purpose. However, the detection of soyabean proteins in meat products presents difficulties related to the composition (meat species, meat quality, soyabean protein source, presence of other non-meat proteins, etc.) and the processing of the meat products, and, although these analytical methods have tried to overcome all these difficulties, there is still not a method enabling quantitative assessment of soyabean proteins in all kinds of meat products.

The method described in this paper for the quantitative measurement of soybean protein in meat products is based on the specificity of immunological techniques, as demonstrated by other investigators. The major improvements claimed are higher sensitivity (0.1% or 0.5 μg glycini11)? economy in volume of antisera per determination (0.1 ml), selective measurement of the “heat-stable” fraction, and suitability for routine analysis.

ABSTRACTIn this study we developed an immunofluorescence method to detect pea protein in meat products. Pea protein has a high nutritional value but in sensitive individuals it may be responsible for causing allergic reactions. We produced model meat products with various additions of pea protein and flour; the detection limit (LOD) of the method for pea flour was 0.5% addition, and for pea protein it was 0.001% addition. The repeatabilities and reproducibilities for samples both positive and negative for pea protein were all 100%. In a blind test with model products and commercial samples, there was no statistically significant difference (p > 0.05) between the declared concentrations of pea protein and flour and the immunofluorescence method results. Sensitivity was 1.06 and specificity was 1.00. These results show that the immunofluorescence method is suitable for the detection of pea protein in meat products.

Simple SummaryTransglutaminases are enzymes used for joining cuts or fragments of meat together to make larger pieces that are easier to handle or a product that is more attractive to consumers. They react differently with various meats and at different inclusion levels, so this study investigated quality traits of intact chicken meat and restructured chicken meat supplemented with different proportions of transglutaminase. The results showed that enzyme-supplemented restructured meat had lower cooking loss and greater tenderness compared to intact meat. Sensory attributes were not affected by the supplemented enzyme, and there was no difference in these attributes compared to intact meat. Therefore, supplementation with transglutaminase could be undoubtedly considered as a valuable contributing agent in improving yield and texture of minced meat, and reducing other additives usually used in chicken meat processing.Transglutaminases (TG) are enzymes that improve the functional properties of proteins in meat products, contribute to the strong cohesion of meat without the further need for the addition of sodium chloride or phosphates, and have a positive effect on the texture of the meat product. This study aimed to investigate the physicochemical and sensory attributes of intact and restructured chicken meat supplemented with different TG proportions. The study was conducted on chicken breast meat samples (n = 40) originating from the line Ross 308. The intact samples were separated from the pectoralis major muscle, whereas the rest of the breast meat was ground, divided into equal parts, and supplemented with TG (0.2%; 0.4%; 0.6%; 0.8%; 1%). The intact meat had the highest cooking loss (19.84) when compared to 0.2% (15.51), 0.4% (15.04), 0.6% (14.95), 0.8% (14.95), and 1% (15.79) TG-supplemented meat. The intact meat had greater shear force (16.90) than 0.2% (5.16), 0.4% (5.39), 0.6% (5.16), 0.8% (5.98), and 1% (6.92) TG supplemented meat. There was no difference between intact meat and TG-supplemented meat in color, taste, odor, texture, and overall acceptability (p > 0.05). Therefore, TG supplementation can be used in improving yield and texture of minced chicken meat.

A review of the legislation concerning the use of vegetable protein products in meat products is given for 15 West European countries. Existing requirements in these countries concerning composition and labeling of meat products containing vegetable protein are compared, and it is shown that wide divergencies exist. Some countries explicitly forbid addition of vegetable protein to meat products, other countries permit such additions in specified amounts to specific meat products and others again do not set limitations on either the amount of vegetable protein or the type of meat products to which they may be added. Labeling provisions, likewise, vary to a great extent. These differences are linked to the regulations on meat products in the various countries which often reflect a strong national tradition. In most of the countries no general approach to regulating use of vegetable proteins in meat products has yet been taken. But a few of the countries are formulating such a policy, and the possible outcome of these ongoing deliberations is outlined.

The addition of phosphates to meat products improves the emulsifying and gelling properties of meat proteins, in turn enhancing overall product quality. The current market trend towards additive-free products and the health issues related to phosphate challenge the industry to develop phosphate-free meat products. The aim of this study was to evaluate the potential of seven protein-based ingredients (pea, blood plasma, gelatin, soy, whey, egg, and potato) to remediate quality losses of emulsified meat products (cooked sausages) upon phosphate elimination. First, the intrinsic gelling and emulsifying characteristics of the proteins were assessed. Next, the proteins were added to phosphate-free sausages, of which quality characteristics during production (viscoelastic behavior and emulsion stability) and of the final products (texture, cooking loss, and pH) were screened. Blood plasma and soy were superior in phosphate-free cooked sausages, as no significant differences in hardness, cooking yield, or stability were found compared to phosphate-containing sausages. Egg and pea also improved the previously mentioned quality characteristics of phosphate-free sausages, although to a lesser extent. These insights could not entirely be explained based on the intrinsic gelling and emulsifying capacity of the respective proteins. This indicated the importance of a well-defined standardized meat matrix to determine the potential of alternative proteins in meat products.

A sensitive HPLC-MS/MS screening method for the simultaneous detection of lupine, pea, and soy proteins in meat products

Simple SummaryThe quality of fresh meat largely relates to water-holding capacity (WHC) which is an important attribute associated with consumer acceptance and food-processing technology. Regarding this, the industry requires methods that can easily, with a great precision, determine the WHC of meat and meat products. The EZ-DripLoss method is relatively new gravimetric method that is used for determination of excessive drip in meat. Currently, there is diversity in the literature regarding the use of EZ-DripLoss methodology. Therefore, this technical note aimed to research drip loss in chicken breast meat measured across the period of three days using two different EZ-DripLoss methodologies. In the standardized EZ-DripLoss method, drip loss is calculated by weighing specialized EZ containers, whereas in the modified EZ-DripLoss method drip loss is calculated by weighing samples. This technical note indicates that different EZ-DripLoss methodology results in different drip loss values in chicken breast meat. Therefore, comparisons of the EZ-DripLoss results should be performed with great caution.The EZ-DripLoss method is relatively new gravimetric method that is used for the determination of excessive drip in meat. The literature reports diversity regarding the use of EZ-DripLoss methodology. In the standardized EZ-DripLoss method, drip loss is calculated as the change in the container weight, whereas in the modified EZ-DripLoss method, it is calculated as the change in sample weight. This technical note aimed to research the relationship between these two methods on chicken breast meat (40 broilers from the line Ross 308) during the measurement interval of 24, 48, and 72 h. The results showed statistically a significant positive linear increase in drip loss values regardless of the used method during all of the investigated measurement intervals. At 24, 48, and 72 h of storage, the average drip loss in the weighed samples was 0.77, 1.40, and 2.23 percentage points greater than in the not weighed samples (p < 0.0001), respectively. A strong and positive estimate of correlation coefficients between the drip loss of weighed and not weighed samples was found after 24 h (r = 0.95), 48 h (r = 0.92), and 72 h (r = 0.86). This technical report indicates that the used EZ-DripLoss methodology highly influences the drip loss in chicken breast meat and the comparisons of the EZ-DripLoss results should be performed with great caution.

Soy proteins are commonly used in the food industry thanks to their technological properties. However, soy is, along with cow’s milk, eggs, wheat, peanuts, tree nuts, fish, crustaceans, and molluscs, responsible for around 90% of food allergies, and is also one of the foodstuffs that can cause anaphylaxis. The aim of this work was to compare the immunofluorescence method for the detection of soy protein in meat products purchased from the retail market with other microscopic methods (immunohistochemical and histochemical), with the ELISA reference method and with the confirmatory results. Within the research, 127 meat products purchased in the retail network were examined using the immunofluorescence method used for the detection of soy protein. The method was compared to Enzyme-Linked ImmunoSorbent Assay (ELISA), immunohistochemical, and histochemical methods. According to McNemar’s test, non-compliance between the immunofluorescence method and immunohistochemical method was low. In addition, a significant difference between the fluorescence method and ELISA (P &lt; 0.05) and a highly significant difference between the fluorescence method and histochemical examination (P &lt; 0.01) was found. The immunofluorescence method was also compared with confirmatory results. According to McNemar’s test, non-compliance between the immunofluorescence method and confirmatory results was low. The results showed the possibilities of this new method to detect the content of soy protein in meat products.