Seasonal variation may influence flavor profile of black walnuts

February 12, 2016

A study published in the Journal of Food Science evaluates the sensory profile of black walnut (Juglans nigra L.) cultivars. There are more than 750 black walnut cultivars, which ripen at different times of the year. Despite this, they are usually harvested at the same time. With many environmental factors influencing nut production, yield, and quality, it is important to understand the effects of growing season on the flavor profile of black walnuts.

The researchers set out to determine the sensory profile, including appearance, aroma, flavor, and texture, of nut kernels from 10 black walnut cultivars (Davidson, Sparrow, Neel, Emma K, Tomboy, Football, Vandersloot, Brown Nugget, Pounds, and Sparks 127). In addition, they wanted to determine the effects of growing season on flavor profile of seven black walnut cultivars (Emma K, Brown Nugget, Sparrow, Football, Tomboy, Sparks 127, and Davidson).

The cultivars were evaluated by a trained panel over two growing seasons to determine the seasonal variation in the sensory profile. The black walnut kernels produced in 2013 differed on five of 23 flavor attributes. In addition, the panel also evaluated appearance, aroma, and texture. They found that the 10 cultivars differed on three appearance, one aroma, and two texture attributes.

The researchers compared these profiles to results collected in 2011 to determine differences between growing seasons. The cultivars showed an interaction effect between year and cultivar for four flavor attributes, and showed a main effect of year—meaning that the attribute intensity depends on growing conditions and not necessarily as much on cultivar—for six flavor attributes. No flavor attributes had a main effect of cultivar. In general, flavor attributes had higher intensities in 2011 than in 2013. These results suggest that seasonal variation may influence flavor profile more than cultivar.

The researchers concluded that seasonal variation (in this case, growth year) is a critical factor to consider when determining flavor profile of agricultural products and highlights the importance of having representative samples for testing. Using samples from only one growing season may not provide adequate information for the long term when testing agricultural products.