Chemical Indices of hazelnut roasting: quality and technological descriptors

The quality of food products is undoubtedly a challenging and complex issue; it refers, in a first instance, to the compliance with legal standards on health risks, environment, animal welfare and ethical requirements, but it is also related with the sensory impact due to the flavour, smell and appearance. Due to specific quality properties, some products achieve further added value thanks to their origin and manufacturing and/or to processing practices. EU encourages these productions and recognizes, through a series of quality labels, product peculiarity and specificity (i.e., Protected Designation of Origin (PDO), Protected Geographical Indication (PGI) and Traditional Specialty Guaranteed (TSG)). Origin Labeled Products, as EU Regulation explicitly refers, should be different from standard products for their qualities or characteristics evoking the concept of “specificity”. The product is said to be differentiated if it has characteristics that are specific and measurable in the sense of substantial or intrinsic and, as a consequence, consumers perceive it as such (Bariolle 2002). Italian Corylus avellana L. cultivars received the EU quality labels: “Nocciola Romana” also named “Tonda Gentile Romana” from Viterbo - Lazio is PDO labeled (IT/PDO/51705/0573) while the “Nocciola del Piemonte” from Piedmont (IT/PGI/0217/0305) and “Nocciola di Giffoni” from Avellino province (IT/PGI/0117/1538) are both PGI products. These cultivars are recognized to be specifically suited for roasting, peeling and gauging, qualities that are of a great importance in the confectionary industry for the production of hazelnut paste (manteca), granulate, confectionary specialties or for a direct consumption of the whole nut. Moreover, the Turkey is the leading hazelnut producer, according with the last updated FAO report on world crop production (FAOStat), with the 65% (500,000 tons) of the world production while Italy, the second country in the ranking, covers the 14% (104,900 tons) of the production followed by US and Spain with the 6 and 4% respectively. In this context it is of great importance the possibility to distinguish raw or roasted hazelnuts of different variety/cultivar and geographical origin as well as to provide detailed information on chemical composition and sensory quality of food end and semi-finished products. Analytical methods for product quality assessment should give reliable and robust results and procedures should be developed and validated, in terms of performance, to be effective and informative when adopted for quality/origin qualification as for process monitoring. The present study reports the experimental results obtained by applying a validated HS-SPME-GC-MS method to monitor raw and roasted hazelnut volatiles. The method enables the qualitative and quantitative determination of key-analytes (markers) and allows to reveal technological and quality indicators to classify and qualify hazelnut samples of different geographical origin. In particular in this study an Italian cultivar from Piedmont, named Tonda Gentile Trilobata known also as “Nocciola del Piemonte” (EU Quality registration code IT/PGI/0217/0305) and a Turkish high quality blend from “Ordu” region consisting of three major cultivars: Tombul, Palaz and Kalinkara have been investigated. Roasting has been followed different time/temperature protocols in a lab-scale ventilated oven and in two industrial plants: a hot air dry roasting and an infrared ray roasting. Robust indicators of technological treatments and quality markers for aroma qualification and origin authentication are presented.