Impact of industrial shelling and blanching on almond kernel integrity and color

Abstract

Spanish almond industry expressed concerns over increasing kernel breakage during processing, particularly with the new almond cultivars introduced since 2005. This research aimed to (i) evaluate kernel breakage across different almond cultivars during shelling and blanching in Spanish industrial machines; (ii) identify the main factors contributing to breakage; and (iii) assess the impact of blanching on kernel color. Shelling breakage was lower in ‘Belona’ (2%) than ‘Guara’ (7%), potentially attributed to its higher water absorption and round shape. However, blanching, drastically increased breakage in ‘Belona’ (42%) compared to ‘Guara’ (29%). A large variability among cultivars (‘Carmel’ 12%, ‘Belona 2’ 32% significantly similar to ‘Guara’ 29%, and ‘Lauranne’ 43% significantly similar to ‘Belona’ 42%), was observed, but also between different batches of the same cultivar (‘Belona’ 42% and ‘Belona 2’ 32%), probably due to different growing conditions. ‘Lauranne’ and ‘Belona’ exhibited a higher tendency to produce halves, whereas ‘Guara’ produced more pieces. Kernel breakage during blanching was significantly correlated with kernel width (r = 0.57***), protein, (r = − 0.83***), and fat content (r = 0.67***). Blanching significantly affected kernel color (‘Carmel’, ‘Belona 2’, ‘Guara’, ‘Lauranne’, ‘Belona’; ΔE = 19, 14, 12, 11, 10, respectively) and was identified as a critical control point for breakage across the processing line.