Determination of the concentration of hazelnut as a food ingredient: a perspective for food control

Hazelnut is a common food ingredient, used in high concentrations in hazelnut spreads, chocolates, cookies, snacks, nutrition bars, and confectionary products as well as in gluten-free flour. It is generally detected as a food allergen; yet, another perspective of food control is to confirm the declared amount of the food ingredient in the final product to prevent deceiving consumers. This study aimed to quantify the elevated levels of hazelnut in hazelnut containing food products by using an enzyme -linked immunosorbent assay (ELISA) test. During this quantification, the roasting temperature and duration of different hazelnut ingredients were evaluated. The ELISA test was shown to be used to confidently quantify hazelnut roasted at up to 140 °C for 10 min. Above those conditions, the proteins gradually deteriorated. Additionally, the amount of hazelnut detected from hazelnut flour was less than expected, suggesting that hazelnut flour had particles that prevented the release of proteins into the test solution, while the amount of hazelnut detected from hazelnut paste which had already been ground to release its proteins was as expected. These results demonstrated the importance of sample preparation before the analysis with a mill ball or a grinder. The data tables reported might be used for comparable quantification of hazelnut ingredient if the condition of the ingredient was declared by the producer.