Child Obesity 2018: Sensory evaluation of different walnut species- Jelena Vidic- University of Roehampton, UK
Walnut (Juglans regia L.) is a plant native to temperate and sub-tropic regions of the northern hemisphere and is considered to have very good impacts on human health. Thus, many recommend having walnuts in their every-day diet in order to prevent multiple diseases. Sensory walnut evaluation holds a significant part in determining the strong and unusual tastes, as well as in comparing the sensory characteristics between different walnut varieties using all five sensory organs. The objective of the study is put on determining the intensity of the sensory characteristics between 16 different varieties, after what they were to be compared regarding to their country of origin. In the sensory laboratory at the Faculty of Food Technology and Biotechnology, eight sensory examiners carried out the sensory evaluation using the quantitative descriptive analysis. The examiners measured 14 sensory parameters overall - shell colour, scent on nut, scent on wood, strength and hardness of the fruit, crispness, putty-like consistency, sweetness, acidity, bitterness, oil aroma, rancidity and overall impression. The best overall impression among the examiners had the varieties from France.
Preparation of nuts.
Nuts from walnut cultivars used in the experiment were harvested in Sept. and Oct. 1988, at »80% hull dehiscence, from healthy commercial orchards in the Gridley/Live Oak area of California. The nuts were immediately dried and stored at room temperature for » 1 to 3 weeks, then transferred to UC Davis, and stored in plastic bags at 0C. Moisture content was calculated by drying 100 g of kernels at 70C in a vacuum oven for 36 hr and then reweighing. Kernel moisture content was found to be variable among cultivars and most cultivars well exceeded the optimum range of 3.2% to 3.8% (R.E. Gunnerson, personal communication). The whole nuts were therefore redried at 43C for 3-6 hr, cooled at room temperature, and then refrigerated in plastic bags for several days to equalize nut moisture content. The nuts were then retested; the moisture content of all the cultivars was between 3.0% and 3.4%. Northern California black walnuts (J. hindsii), used in the first training session, were dried and stored in the same manner, but were not tested for moisture content. Nuts of each cultivar were cracked the day before they were to be tested, and the kernels were broken into pieces about one-sixth the size of a kernel-half. The kernels were then stored overnight in a plastic bag at 2C. Sensory evaluation. Twenty-one people associated with the Pomology Dept., UC Davis, were selected as judges based on motivation and availability. The panelists were advised to chew several kernel pieces, expectorate, and rinse with water between samples. However, due to individual preferences and the small number of nuts being sampled, they were given the choice to swallow or expectorate the nuts and to rinse two times after each sample or only after each trio of samples. In either case, they were told to use the same technique for the entire experiment. All evaluations were carried out in individual booths under red light at 22C. In the initial difference testing, ‘Hartley’ was compared to seven other cultivars using the duo-trio method (Institute of Food Technologists, 1981). Each day, one cultivar was tested against ‘Hartley’ in four replications. One bowl of ‘Hartley’ kernels (coded as “reference”) was placed on each panel member’s tray along with four pairs of portion cups (coded with random three-digit numbers) that contained »6-8 g of kernels. In each pair, ‘Hartley’ kernels and kernels of the other test cultivar were presented in a random order.