14A-51

Optimization of the hazelnut roasting process

S. SAKLAR¹, Z. Hicsasmaz², S. Katnas³, and S. Ungan². (1) Food Science and Technology Research Institute, TUBITAK, P.O. Box 21 Gebze, Kocaeli, 41470, Turkey, (2) Food Engineering Department, Middle East Technical University, Ankara, 06531, Turkey, (3) Chemical Engineering Department, Gazi University, Faculty of Engineering and Architecture, Maltepe, Ankara, 06570, Turkey

JUSTIFICATION:

Türkiye supplies 80% of the hazelnut demand of various food industries due to their color, flavor and texture. However, definition of whole roasted hazelnut kernels and their production schemes require more standardization.

OBJECTIVES:

To optimize roasting parameters with respect to roasting temperature, air velocity and roasting time to obtain desired color, roasted hazelnut flavor, crispy and crunchy texture.

METHODS:

We used an experimental roaster where hazelnuts stay on a rotatable square wire mesh basket. We applied a 3-variable, 5-level Central Composite Design to study the effect of roasting temperature (111-179°C) and time (12-28 min), and air velocity (0.3-3.7 m/s) on hazelnut flavor, crispiness and crunchiness, moisture content, color and texture. We used Spectrum Method for sensory tests, Hunter L, a, b scores for color, compression tests for texture. We made a consumer test to determine the acceptable samples. We determined the production region that met consumer acceptance by superimposing contour plots for roasted hazelnut, burnt and painty flavors, crispiness and crunchiness, Hunter L, a, b values and DE, moisture content, and mechanical response variables.

RESULTS:

Color and flavor depended on non-enzymatic browning reactions. Crispiness and crunchiness, and mechanical response variables related with the moisture content. Duncan Range Test showed that very dark and light roasted samples had lower scores than the neither like nor dislike category that corresponded to 165 and 125°C roasting temperature, 3 and 1 m/s air velocity and 25 and 15 minutes roasting time, respectively. Superimposing contour plots resulted in unacceptable products below 125°C. At low air velocity (0.3 m/s), the acceptable region lied between 165-179°C for 20-25 min roasting time. The region slid to lower temperatures as air velocity increased.

SIGNIFICANCE:

In the literature, no studies are available on the investigation of the attributes of hazelnuts with good eating quality and process conditions required to produce them.