Sensory evaluation of different levels of roasting of New Zealand grown hazelnuts

Abstract

Hazelnuts (Corylus aveIIana L.) are a very recent addition to commercial horticulture in New Zealand and Whiteheart has been selected as the primary commercial cultivar. No published information is available on the optimum temperatures needed to roast the dried nuts. An experiment was designed to investigate three different roasting treatments, blanching, light roast and full roast using a conveyer type roasting oven set at 200°C. The roasted samples were then analysed for proximate contents and evaluated using a taste panel. The appearance, texture, flavour and overall appearance was evaluated by 63 tasters at one time. The blanched nut was appreciated for its colour but it was considered too chewy and bland in taste compared to the roasted nuts. Each one of the heat treatments gave an improved rating for all of the attributes measured. Roasting in the oven set at 200°C for 6 minutes (full roast) was the treatment appreciated most by all tasters. Analysis of the correlation coefficients showed that the overriding impression about the hazelnuts comes from the flavour of the nut followed by its texture. The overall appearance of the nut was not highly rated by the tasters once the hazelnuts had been heat treated.