Comparing physical measures and mechanical cracking products of ‘Nonpareil’ almond (Prunus dulcis [Mill.] D.A. Webb.) with two advanced breeding selections

Kernels of ‘Nonpareil’ almond and advanced breeding selections 23.5–16 and 23–122 were evaluated for similarities and differences in commercially important kernel characteristics. These three almond types did not differ in kernel mass, kernel length and width, nor in kernel color coordinates, luminosity and hue. ‘Nonpareil’ kernels were observed to be significantly (p ⩽ 0.05) thicker than kernels of 23.5–16 and 23–122. Chroma value of ‘Nonpareil’ kernels was significantly higher (p ⩽ 0.05) than that of 23–122, but did not differ from that of 23.5–16. Bulk in-shell samples of the three almond types were then compared after a mechanical cracking treatment using identical roller settings in a research-sized commercial cracking machine. Sticktight content varied significantly (p ⩽ 0.01) amongst the three almond types prior to cracking bulked samples. The cracking treatment significantly reduced (p ⩽ 0.01) sticktight content in each of the almond samples and a significant interaction (p ⩽ 0.01) was observed between almond types and cracking treatment with regard to sticktight content. ‘Nonpareil’ and 23.5–16 did not differ in sticktight content either prior to or after the cracking treatment. The three almond types varied significantly (p ⩽ 0.05) in the various categories of edible kernels (whole, double, scratched, broken & chipped) after the cracking treatment.