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Biosensor immunoassay for traces of hazelnut protein in olive oil.

Bremer MG, Smits NG, Haasnoot W - Anal Bioanal Chem (2009)

Bottom Line: The fraudulent addition of hazelnut oil to more expensive olive oil not only causes economical loss but may also result in problems for allergic individuals as they may inadvertently be exposed to potentially allergenic hazelnut proteins.To improve consumer safety, a rapid and sensitive direct biosensor immunoassay, based on a highly specific monoclonal antibody, was developed to detect the presence of hazelnut proteins in olive oils.Recoveries obtained with an olive oil mixed with different amounts of a hazelnut protein containing hazelnut oil varied between 93% and 109%.

View Article: PubMed Central - PubMed

Affiliation: RIKILT-Institute of Food Safety, Wageningen UR, P.O. Box 230, 6700 AE Wageningen, The Netherlands. monique.bremer@wur.nl

ABSTRACT
The fraudulent addition of hazelnut oil to more expensive olive oil not only causes economical loss but may also result in problems for allergic individuals as they may inadvertently be exposed to potentially allergenic hazelnut proteins. To improve consumer safety, a rapid and sensitive direct biosensor immunoassay, based on a highly specific monoclonal antibody, was developed to detect the presence of hazelnut proteins in olive oils. The sample preparation was easy (extraction with buffer); the assay time was fast (4.5 min only) and the limit of detection was low (0.08 microg/g of hazelnut proteins in olive oil). Recoveries obtained with an olive oil mixed with different amounts of a hazelnut protein containing hazelnut oil varied between 93% and 109%.

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Colloidal gold-stained Western blot of crude hazelnut oil extract (M = molecular mass marker, Oil = hazelnut oil extract)
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Fig4: Colloidal gold-stained Western blot of crude hazelnut oil extract (M = molecular mass marker, Oil = hazelnut oil extract)

Mentions: Four hazelnut oils were extracted and tested in the BIA. In one of the Greek virgin hazelnut oils, a high concentration of approximately 1,670 μg/g of hazelnut proteins was measured (after analyzing in and correcting for high diluted extracts). In the other Greek hazelnut oil, a concentration of only 0.35 μg/g hazelnut proteins was detected. In both hazelnut oils from the Dutch local market, the concentration of hazelnut proteins was below the LOD of 0.08 μg/g. A hazelnut oil analyzed by Teuber et al. [5], which was a blend of refined and unrefined oil in unknown proportion, contained 62 μg/mL of hazelnut protein. It is clear that the protein content of hazelnut oils depends on the refinement grade and that it can vary significantly. Similar observations were made for other vegetable and nut oils [5, 19–21]. In general, crude oils may contain up to a few hundred micrograms of protein per milliliter whereas highly refined oils may have a 100-fold lower protein content [6]. From the protein content, it is obvious that one Greek hazelnut oil was a crude oil and that the low-priced ones from the local market were highly refined. An important observation is that proteins present in oils can still be allergenic [5, 6]. Therefore, olive oils adulterated with crude hazelnut oils, even at a low percentages, may contain enough protein to pose a threat to allergenic individuals. A protein profile of the crude hazelnut oil extract is shown in Fig. 4. This protein profile and the profile of the hazelnut extract used for calibration are similar (Fig. 1). The protein bands from the hazelnut oil extract are less intense and some bands seem to be missing due the low protein concentration in the extract. However, all proteins detected by MAb 50-5H9 (Fig. 1) are present in the oil extract. This demonstrates that the extract used for calibration is representative for extracts obtained from (crude) hazelnut oil and can be used for calibration.Fig. 4


Biosensor immunoassay for traces of hazelnut protein in olive oil.

Bremer MG, Smits NG, Haasnoot W - Anal Bioanal Chem (2009)

Colloidal gold-stained Western blot of crude hazelnut oil extract (M = molecular mass marker, Oil = hazelnut oil extract)
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2724632&req=5

Fig4: Colloidal gold-stained Western blot of crude hazelnut oil extract (M = molecular mass marker, Oil = hazelnut oil extract)
Mentions: Four hazelnut oils were extracted and tested in the BIA. In one of the Greek virgin hazelnut oils, a high concentration of approximately 1,670 μg/g of hazelnut proteins was measured (after analyzing in and correcting for high diluted extracts). In the other Greek hazelnut oil, a concentration of only 0.35 μg/g hazelnut proteins was detected. In both hazelnut oils from the Dutch local market, the concentration of hazelnut proteins was below the LOD of 0.08 μg/g. A hazelnut oil analyzed by Teuber et al. [5], which was a blend of refined and unrefined oil in unknown proportion, contained 62 μg/mL of hazelnut protein. It is clear that the protein content of hazelnut oils depends on the refinement grade and that it can vary significantly. Similar observations were made for other vegetable and nut oils [5, 19–21]. In general, crude oils may contain up to a few hundred micrograms of protein per milliliter whereas highly refined oils may have a 100-fold lower protein content [6]. From the protein content, it is obvious that one Greek hazelnut oil was a crude oil and that the low-priced ones from the local market were highly refined. An important observation is that proteins present in oils can still be allergenic [5, 6]. Therefore, olive oils adulterated with crude hazelnut oils, even at a low percentages, may contain enough protein to pose a threat to allergenic individuals. A protein profile of the crude hazelnut oil extract is shown in Fig. 4. This protein profile and the profile of the hazelnut extract used for calibration are similar (Fig. 1). The protein bands from the hazelnut oil extract are less intense and some bands seem to be missing due the low protein concentration in the extract. However, all proteins detected by MAb 50-5H9 (Fig. 1) are present in the oil extract. This demonstrates that the extract used for calibration is representative for extracts obtained from (crude) hazelnut oil and can be used for calibration.Fig. 4

Bottom Line: The fraudulent addition of hazelnut oil to more expensive olive oil not only causes economical loss but may also result in problems for allergic individuals as they may inadvertently be exposed to potentially allergenic hazelnut proteins.To improve consumer safety, a rapid and sensitive direct biosensor immunoassay, based on a highly specific monoclonal antibody, was developed to detect the presence of hazelnut proteins in olive oils.Recoveries obtained with an olive oil mixed with different amounts of a hazelnut protein containing hazelnut oil varied between 93% and 109%.

View Article: PubMed Central - PubMed

Affiliation: RIKILT-Institute of Food Safety, Wageningen UR, P.O. Box 230, 6700 AE Wageningen, The Netherlands. monique.bremer@wur.nl

ABSTRACT
The fraudulent addition of hazelnut oil to more expensive olive oil not only causes economical loss but may also result in problems for allergic individuals as they may inadvertently be exposed to potentially allergenic hazelnut proteins. To improve consumer safety, a rapid and sensitive direct biosensor immunoassay, based on a highly specific monoclonal antibody, was developed to detect the presence of hazelnut proteins in olive oils. The sample preparation was easy (extraction with buffer); the assay time was fast (4.5 min only) and the limit of detection was low (0.08 microg/g of hazelnut proteins in olive oil). Recoveries obtained with an olive oil mixed with different amounts of a hazelnut protein containing hazelnut oil varied between 93% and 109%.

Show MeSH