Sensory Attribute Preservation of Walnuts Using Walnut Edible Coatings and Polyphenols

ASENSIO, C. M.; NEPOTE, V.; MARTIN, M. P.; GROSSO, A. L.; GROSSO, N. R.

Chicago

Congreso; IFT Annual Meeting; 2018

Introduction:Walnuts are appreciated because of their pleasant sensory attributes, which are susceptible to deterioration. Edible coatings and antioxidants are known to decrease this process. The objective of this study was to evaluate the preserving effect of walnut protein coatings with the addition of walnut polyphenols as antioxidants on sensory properties of walnuts during storage. Methods:Walnuts (var. Chandler) were coated with walnut protein based coating (WPN), WPN with BHT (WPNB), and WPN with walnut polyphenols (WPNP). Walnuts without coating were used as control sample (WC). The samples were stored for 98 days in an oven at 40 ºC. Intensity ratings of attributes (unstructured line scale 0-150 mm) for descriptive analysis and carotenoid content (CC) changes were evaluated during storage. The attributes evaluated were color, roughness, glossiness, oxidized, walnut flavor, cardboard flavor, sweetness, saltiness, sourness, bitterness, astringent, crunchiness, and hardness. Statistical analysis: MLGyM, LSD-Fisher and Correlation.Significance:Walnuts develop off-flavors, as the result of the formation of compounds that have adverse effects on human?s health. Edible coatings and antioxidant may prolong the shelf-life of this food-product by preventing the formation of these compounds.Results:The intensity ratings of negative attributes like oxidized and cardboard flavors increased in all treatments during storage. On last storage day, WC showed higher intensity ratings in oxidized (63.80) and cardboard (59.73) flavors. The lowest ratings for these attributes were detected in WPNB and WPNP (7.80 and 11.53 in oxidized, and 33.40 and 34.53 in cardboard, respectively). On the other hand, the intensity ratings of the characteristic walnut flavor decreased during storage. This decrease was higher in WC (46.70 on last storage day) and lower in WPNP (74.60). The carotenoid content of WPNP exhibited the highest value on last storage day (2.79 mg/kg), while WC presented the lowest value (1.49 mg/kg). A negative correlation (Pearson) was found between carotenoid content and oxidized flavor (-0.65; p