ABSTRACT
Monoclonal antibodies generated against live cells of Pseudomonas fluorescens have been used in an immunostick enzyme-linked immunosorbent assay (ELISA) format for the detection of Pseudomonas spp. in refrigerated meat and milk. The detection threshold for the immunostick ELISA assay developed in this work is 104 CPU cm-2 for meat and 105 CPU ml-1 for milk samples.
ABSTRACT
A stable hybridoma cell line (B2B) has been produced that secretes a monoclonal antibody (MAb) specific for goat's milk αS2-casein. The MAb B2B was used in two enzyme-linked immunosorbent assay (ELISA) formats for the detection and quantification of the presence of goat's milk in ewe's milk. In the indirect ELISA format the limit of detection was 0.5 to 15% (vol/vol) substitution of goat's milk for ewe's milk. Afterwards, a competitive indirect ELISA was successfully developed for the detection of 0.25 to 15% (vol/vol) of goat's milk in ewe's milk. This competitive indirect ELISA is a very sensitive assay; it can be performed in less than 5 h and is not influenced by the heat treatment of milk.
ABSTRACT
An immunostick enzyme-linked immunosorbent assay (ELISA) has been developed for the rapid detection of cow's milk in ewe's milk or cheese. The assay uses a monoclonal antibody (AH4) produced against bovine ß-casein for the detection of cow's milk or cheese bound to the paddles of immunostick tubes. This immunostick ELISA allows the visual identification of ewe's milk containing more than 1% of cow's milk or cheese samples containing more than 0.5% of cow's cheese.
ABSTRACT
An indirect enzyme-linked immunosorbent assay (ELISA) has been developed for the identification of smoked meat from salmon ( Salmo salar ), trout ( Oncorhynchus mykiss ), and bream ( Erama raii ). The assay uses polyclonal antibodies raised in rabbits against soluble proteins of muscle from salmon (anti-SSP), trout (anti-TSP), and bream (anti-BSP) which are rendered species-specific by blocking them with the heterologous soluble muscle proteins. The blocked antibodies were used to detect the samples from smoked fish bound to the wells of a microtiter plate. Immunorecognition of polyclonal antibodies adsorbed to fish samples was made with goat anti-rabbit immunoglobulins conjugated to the enzyme horseradish peroxidase. Subsequent enzymic coversion of the substrate allowed clear species identification of smoked meat of salmon, trout, and bream.
ABSTRACT
A sandwich ELISA (enzyme-linked immunosorbent assay) was developed for the detection of defined amounts of bovine milk (1-30%) in ovine milk. Polyclonal antibodies were raised in rabbits against bovine whey proteins (BWP). Resultant antibodies were affinity purified by immunoadsorption of the crude antiserum onto columns containing immobilized ovine, caprine, and BWP, followed by elution of the bovine milk specific antibodies (anti-BWP) from the column containing the bovine proteins. The specific anti-BWP antibodies bound to the wells of a microtiter plate were used to capture the BWP from milk mixtures. Further immunorecognition of the captured proteins was attained with the same specific antibodies conjugated to biotin. ExtrAvidin-peroxidase was used to detect the biotinylated antibodies bound to their specific antigens. Subsequent enzymic conversion of substrate gave clear optical density differences when assaying mixtures containing variable amounts of bovine milk.
ABSTRACT
A double-antibody sandwich ELISA (enzyme-linked immunosorbent assay) has been successfully developed for the detection of defined amounts of pig meat (1-50%) in raw beef. Antibodies against pig sarcoplasmic extracts were produced in rabbits. Pig-specific antibodies were affinity purified by removing antibodies which crossreacted with horse, chicken or beef extracts followed by immunoadsorption and elution from a pig-extract column. The ELISA involved capturing antigens in sarcoplasmic extracts with pig specific antibodies immobilized on 96-well plates, detecting bound antigen with pig specific, horseradish peroxidase-labeling antibody, and measuring peroxidase activity by the conversion of a clear substrate to a colored product.
ABSTRACT
Changes in bacterial numbers, metmyoglobin percentage and 2-thiobarbituric acid number during the chill storage of pork longissimus dorsi packed with air, carbon dioxide, carbon dioxide and oxygen or vacuum-packed in plastic bags of high (polyethylene) and low (Cryovac BB-1) permeability to gases were studied. The fast increase of viable counts in polyethylene bags showed that plastic films of high permeability are not suitable to extend the shelf-life of meat using modified atmospheres. In Cryovac bags both carbon dioxide-enriched atmospheres and vacuum-packaging inhibited aerobic organisms, keeping the bacterial flora (mainly lactobacilli and Brochothrix thermosphacta ) below the level of 108/cm2 for about 3 weeks. Metmyoglobin formation was not affected by 20% carbon dioxide, whilst 80% oxygen significantly decreased its rate. Metmyoglobin accumulation in vacuum-packed samples was even slower than in the oxygen-enriched atmosphere, but meat color was less attractive in the former than in the latter. Lipid oxidation was not the limiting factor of shelf-life in either of these two atmospheres. Off-odors appeared in both at approximately 20-22 d of storage.
