Analysis of commercial soya additives in meat products

The quantitative aspects of the analysis of commercial soya additives in meat products have been investigated using a polyacrylamide gel electrophoresis technique. Extraction of the proteins from the food products was carried out either in 8 M -urea and 1%, 2-mercaptoethanol at 18 to 20 °C for 16 h (Method 1), or 10 M -urea and 4%, 2-mercaptoethanol at 100 °C for 30 min (Method 2). The proteins in the extracts were separated by electrophoresis on gels containing 6% polyacrylamide and either 6 M -urea (Method 1) or 8 M -urea (Method 2) using a 0.06 M -Tris-glycine buffer, pH 8.6. Densitograms of the stained protein bands were used for the quantitative estimation of the soya proteins. Both methods were found to give quantitative results for the analysis of soya protein additives in beefburgers and sausages. Method 1 was also found to give quantitative results for meat pie fillings and canned meat loaf products, which had been autoclaved at 115 °C for 40 min.     

Nutritional evaluation of meat–soya bean protein product blends

The nutritive value of protein of blends consisting of meat and soya bean protein products, which replaced either 20 or 40 % of protein of meat, were determined in rat feeding experiments. Protein efficiency ratio (PER) and net protein utilisation (NPU) were significantly lower (P<0.05) in blends containing either 20% protein from soya isolate or 40% protein from soya concentrate or soya flakes than blends containing sirloin only. However, there were no significant differences in PER and NPU when model meat (consisting of 70 and 30% protein from sirloin and connective tissue, respectively) was replaced by up to 20% protein from soya isolate or up to 40% protein from soya concentrate.     

Non-spinneret formation and functional properties of fibrous texturates based on a liquid two-phase system water-casein-soya protein isolate

The effects of pH, calcium chloride concentration and coagulation temperature on the yield of sol-fraction during the formation of fibrous texturates made of soya protein isolates (SPI) and their mixtures with casein were studied. The optimal conditions in terms of least protein loss were pH 7.0, 0.05 M calcium chloride and 99 °C. Also studied were functional properties of the fibrous texturates having different relative amounts of the protein components as well as organoleptic properties of combined meat products with a 24% substitution of meat for fibrous texturates. Combined meat products containing fibrous texturates with a casein-SPI ratio of 1:1 had the best organoleptic and technological properties.     

Quantitative immunoassay for soya protein in raw and sterilized meat products

An enzyme-linked immunosorbent assay (ELISA) is described for the quantitative analysis of soya protein in meat products. The assay is applicable to raw and sterilized products and is not dependent on soya variety and type of soya ingredient (concentrate, isolate, etc.). Therefore, the assay can be applied without knowledge of product composition, heat pretreatment and other processing conditions. The ELISA is specific for soya; no interference of other product components has been found. The detection limit of the ELISA is 0.5% soya protein. Qualitative analysis by immunoblotting is possible at much lower concentrations. The antibodies used are specific for sodium dodecyl sulphate (SDS) denatured soya protein subunits. The products are extracted with SDS and 2-mercaptoethanol, which guarantees optimum recovery of the protein components. Product extracts can be analysed directly by ELISA without removal of the SDS by using nitrocellulose as a solid phase.     

The practical application of 3-methylhistidine in determining the lean meat content of food products

Protein-bound 3-methylhistidine, which is present at similar concentrations in various meat species but absent from non-meat proteins, was used to estimate the lean meat content of a range of retailed meat products. The results of the application of this novel method were compared and contrasted with those using standard methods of product analysis. The presence of textured soya protein in products was determined using polyacrylamide gel electrophoresis. Formulae for the calculation of the fat-free lean meat content on the bases of (i) the 3-methylhistidine index for muscle protein and (ii) the connective tissue content, are given. The lean meat contents of products calculated on these bases were found to be of the same order as, but generally lower than, those obtained using standard methods. This was considered to be due to the presence of non-meat proteins, of added connective tissue and/or certain types of offal. These would not be included in the lean meat content, as calculated by the 3-methylhistidine index, but could be legitimately included in the meat content calculated using standard methods according to current practice. A new interpretation of 'meat' in terms of 3-methylhistidine content is given.     

A simple, sensitive enzymatic method for quantitation of soya proteins in soya-meat blends

A method was developed for the detection and quantitation of soya proteins in soya-meat blends. The procedure involves acid hydrolysis of soya, meat or soya-meat blends and determination of free galactose plus arabinose using galactose dehydrogenase. Acetone powders of the various systems were also examined. Average galactose levels in soya flours, soya concentrates and soya isolates were 674,600 and 66 μM galactose equivalents per gram of product, respectively. Beef and pork contained less than 1 μM per gram of raw product. The galactose plus arabinose values for soya-meat blends were linearly dependent on the amount of soya added. The method is sensitive and capable of detecting less than 0·2% soya flours or concentrates and less than 2% soya isolates in meat products.     

An assessment of commercially available reagents for an enzyme-linked immunosorbent assay (ELISA) of soya protein in meat products

An enzyme-linked immunosorbent assay (ELISA) procedure based on a limited supply of specially prepared experimental immunoreagents and designed to measure levels of soya protein in raw or processed mixed meat products has already been published. This report describes a modified method with commercially available immunoreagents suitable for routine use; its response to a range of commercial soya ingredients has been checked using a particular soya protein isolate (Unisol, Unimills BV) as arbitrary standard. Individual soya components and possible cross-reacting food materials have also been investigated. Both the original and modified methods have been applied to a set of model beefburgers containing known levels of Unisol. There was good agreement between observed and calculated levels in raw and heat-set beefburgers; sterilised samples gave a decreased but linear response. The procedure is recommended for the examination of meat products in non-specialised laboratories.     

Identification of Biomarkers of Horse Muscle Tissue Using Proteomic Strategy

Proteomic analysis of horsemeat detected protein fractions, which were located on two-dimensional electrophoregram over a wide range of molecular masses and isoelectric points. The majority of the revealed proteins possessed molecular masses from 10 to 95 kDa. More than 130 protein fractions were detected, for which the proteomic profiles were similar to those of beef. Mass-spectrometric characteristics of seven horse proteins, in particular, the myosin light chains (MLC) and the tropomyosin proteins were obtained. Several proteins of MLC family in combination with tropomyosin proteins can be considered to be biomarkers, useful in analyzing raw meat and meat products containing horsemeat.     

Review: Soya protein products‐their processing,functionality, and application aspects

Abstract

Soya protein products are very interesting ingredients because of their ready availability, functionality, nutritional value, and price. This review covers the processing, functionality, and application of the various soya protein products, that is, full‐fat soya flours, defatted soya flours and grits, soya protein concentrates, soya protein isolates, textured soya products, and modified soya proteins. The choice of food manufacturers between these soya protein products depends on the functional properties, performance in the end products, and price. According to our experience soya protein concentrates offer a proven functionality at the right price, especially for applications in meat products. Soya protein products can help to meet the protein requirements of the modern food industry economically.     

Biological value of the proteins of a sausage product incorporating a combined protein preparation based on slaughterhouse blood

The authors discuss experimental data obtained in the course of investigation of the biological value of proteins of combined meat products containing decolorized blood obtained with the use of a new physical method. Analysis according to the amino acid score revealed that the combination prepared from blood protein, milk serum and eggs would make it possible to replace beef and pork proteins to any extent. The biological experiments showed that the designed protein mixture of blood, milk serum and egg powder would replace not less than 25% of meat proteins. The replacement by 50% and more resulted in a decrease of the biological value of proteins contained by the combined product as compared to control.     

CTAB electrophoresis and immunoblotting: a new method for the determination of soy protein in meat products

A CTAB electrophoresis method that is able to separate soy protein on the basis of molecular mass is introduced. The cationic detergent CTAB (N-cetyl-N,N,N-trimethylammoniumbromide) is not as denaturing as sodium dodecyl sulphate (SDS), and thereby allows separation of proteins that are virtually unchanged from their naturally occurring state. After blotting on a nitrocellulose (NC) membrane, the protein can be detected by a soy-specific antibody. Soy protein isolates, concentrates and hydrolysates as well as meat products containing these soy protein products were separated by CTAB electrophoresis and blotted on NC membranes. As little as 0.5% soy protein in meat products could be detected, even if the meat product had been heated to 120°C for 30 min during the manufacturing process.     

大豆蛋白在肉制品中的应用

本文详细阐述了大豆蛋白的营养价值和功能特性, 指出了它在肉制品中的添加方法和应用要点。     

Investigation of methods to detect mechanically recovered meat in meat products - IV: Immunology

The possibility of using immunological techniques as a method for the detection of mechanically recovered chicken meat in meat products has been investigated in this preliminary study. Antibodies were raised against a low molecular weight fraction (≤ 30 kDa) of chicken bone marrow proteins and an enzyme-linked immunosorbent assay (ELISA) developed. The system was used to test for the presence of mechanically recovered meat (MRM) in a range of product types, from raw chicken meat through to heat processed samples. The results show that it is possible to raise antibodies to chicken bone marrow proteins which show a strong reactivity with chicken and turkey MRM but show little reaction with extracts of MRM and hand deboned meat of other common meat species. However, blood, skin and soya all affected the accuracy of the ELISA.

This study has demonstrated the potential for the use of an immunological procedure as a rapid test for MRM. The selectivity of the antiserum would, however, have to be increased before this procedure could be considered as a suitable technique for the detection of MRM in meat products.     

Polymerase chain reaction (PCR) in the quality and safety assurance of food: Detection of soya in processed meat products

A new method for the specific and sensitive detection of soya (Glycine max) in processed meat products has been developed using polymerase chain reaction (PCR) technology. The presence of soya deoxyribonucleic acid (DNA) from several soya protein concentrates was determined with two pairs of specific oligonucleotides yielding a 414-bp (bp=base pair) fragment and an internal 118-bp fragment amplified from the soya lectinLe1 gene. The test detected DNA from textured soya protein concentrates in meat products at a level of 1% and was confirmed by a commercially available enzyme-linked immunosorbent assay (ELISA).     

Effect of soya consumption on heptatic monooxygenase enzyme system and some lipid parameters in rats

Young male rats were fed with diets containing Hungarian soya products (extruded or granulated soya preparates) as the only source of protein for four weeks. The weight gain of the animals, the cholesterol and triglyceride content of liver and the activity of the hepatic monooxygenase system were studied. 20% soya protein in the diet (either from extruded or from granulated soya products) supplemented with sulphur containing amino acids met the protein requirement of the young growing rats. In a separate experiment the protein depletion-repletion method was used to investigate the effect of Purina 500 E soya protein isolate on the above mentioned parameters. The results indicate that diets containing 20% soya protein are satisfactory for the regeneration of the protein depleted animals.     

Species-specific expression of various proteins in meat tissue: Proteomic analysis of raw and cooked meat and meat products made from beef,pork and selected poultry species

The aim was to search for proteins differentiating the six species (cattle, pig, chicken, turkey, duck and goose) and relatively stable during the meat aging and only slightly degraded in ready-made products. The two-dimensional electrophoresis was used for analysis of the protein profiles from raw meat and frankfurters and sausages (15 products). The observed species-specific differences in protein expression in raw meat were retained in processed products after finishing the entire technological process. Regulatory proteins, metabolic enzymes, some myofibrillar and blood plasma proteins were identified, which were characterised by the electrophoretic mobility specific to the given species. Large differences in the primary structure were observed in serum albumin, apolipoprotein B, HSP27, H-FABP, ATP synthase, cytochrome bc-1 subunit 1 and alpha-ETF. Some of these proteins have potential to be used as markers in authentication of meat products.     

Detection of genetically modified organisms in processed meat products on the Serbian food market

The addition of soybean proteins to processed meat products has significantly increased in recent years due to the interesting functional and nutritional properties of these vegetable proteins. Since the Roundup Ready (RR) soybean is the only transgenic soybean line approved for market in EU this work was aimed at monitoring its presence in meat products on the Serbian food market. The extracted DNA was analyzed using duplex polymerase chain reaction (PCR) with primer pairs aimed at the lectin gene and 35S promoter. Samples positive for the presence of GM soybean were subjected to a real-time quantification of the percentage of RR soya. The results indicated that out of fifty processed meat products examined, twelve gave positive results with 35S promoter and all contained RR soya below 0.1%.     

Utilisation of protein fractions from porcine spleen as technofunctional ingredients in emulsified cooked meat sausages

Spleen is a low commercial value meat by-product from industrial slaughterhouses that is mostly underutilised. In this study, porcine spleens were processed to obtain two protein fractions (i.e. soluble and insoluble extracts in sodium citrate buffer 0.1 m pH 5) and the potential of using them to replace functional ingredients in cooked sausages was assessed. Specifically, a pasteurised insoluble protein extract was used as soy protein replacer in mortadella-type sausages, whereas spray-dried soluble proteins were used instead of sodium caseinate in Frankfurt-type sausages. Both splenic extracts performed well as functional ingredients since no differences in proximate composition, emulsion stability, water-holding capacity or texture were found. The only differences were found in the colour of the sausages containing the soluble protein extract, because of the haem and myoglobin content in this ingredient. The results showed that spleens could be a suitable source of non-allergenic functional proteins for meat products.     

Myoglobin Analysis for Determination of Beef, Pork, Horse, Sheep, and Kangaroo Meat in Blended Cooked Products

This method allows the concurrent detection of several types of animal muscle meat in comminuted, cooked meat products. Meat proteins were dissolved in a solvent containing 8M urea and dithioerythritol and separated by electrofocusing on an ultra-thin polyacrylamide gel, containing urea. The proteins were then transferred to nitrocellulose by electroblotting and the blot was incubated with anti-human myoglobin serum, a linking antibody, peroxidase-antiperoxidase (PAP) immune complex, and enzyme-substrate. Detection of less than 10% pork, horse and sheep meat was possible in a beef-based meat product which had been heated to an internal temperature of 120°C for 5 min. The method is not suitable for detection of chicken and turkey meats.