Sensory attribute preservation of coated walnuts

GROSSO, A. L.; GROSSO, A. L.; NEPOTE, V.; ASENSIO, C. M.

Chicago

Congreso; IFT Annual Meeting; 2016

The walnut seeds are known because of their pleasant sensory attributes and health benefits. Walnuts are susceptible to deteriorate and to develop rancid flavor. Edible coatings can decrease deterioration process because they act as barrier. The objective of this study was to evaluate the preserving effect of edible coatings on sensory properties of walnuts during storage. Walnuts (var. Chandler) were coated with edible films: carboxymethyl-cellulose (CMC), methyl-cellulose (MC), and whey protein (PS), using immersion technique. Walnuts without coating were used as control sample (NC). Descriptive analysis and consumer´s acceptance tests were performed on walnut samples. The attributes (measured on an unstructured line scale 0-150 mm) analyzed by descriptive analysis were color, roughness, glossiness, oxidized, walnut flavor, cardboard flavor, sweetness, saltiness, sourness, bitterness, astringent, crunchiness, and hardness. Flavor acceptance was evaluated for a consumer test using a 9-point hedonic scale. The samples were stored for 210 days at room temperature (23 ºC). The results were statistically analyzed (MLGyM, AM y Test LSD-Fisher). The intensity rantings of negative attributes like oxidized and cardboard flavors increased in all treatments during storage. On the last day of storage, NC showed higher intensity ratings (38.76 in oxidized and 22.25 in cardboard flavors). The lowest ratings of these attributes were detected in MC (7.81 in oxidized and 16.58 in cardboard). On the other hand, the intensity ratings of walnut flavor and sweetness considered positive attributes for this product decreased during storage. The decrease of walnut flavor intensity was higher in NC (61.68 on last storage day) and lower in MC (75.86 on last storage day). The other analyzed attributes did not change significantly their intensity ratings during storage. The acceptance test was performed in fresh product (storage day 0). NC and PS showed better score in flavor acceptance (average value: 6.24). The lowest acceptance flavor score was detected in MC (5.39). Edible coatings help to preserve sensory attributes on walnuts during storage especially walnuts coated with MC. However, some of these coating like MC and CMC can affect consumer acceptance of this food product. Industry Relevant Text Walnuts are an appreciated product around the world because of their sensory characteristics that can lose them for deterioration process caused by deterioration reaction, which generates toxic compounds and rancid tastes. Edible coatings contribute to preserve sensory properties extending the shelf-life of walnuts. These coatings are made from natural compounds and constitute an innocuous method to protect walnuts throughout a year until next harvest. In addition, edible coating application is an easy and economic process to perform by the food industry.