Location: Crop Diseases, Pests and Genetics
Title: Distinguishing nonpareil marketing group almond cultivars through multivariate analyses Authors
Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 6, 2013
Publication Date: September 12, 2013
Citation: Ledbetter, C.A., Sisterson, M.S. 2013. Distinguishing nonpareil marketing group almond cultivars through multivariate analyses. Journal of Food Science. 78(9):S1430-S1436. Interpretive Summary: Kernels from California almond cultivars are divided into five marketing groups based on kernel shape and appearance. These marketing groups are used to assist in the promotion and sale of California almonds, which now represent approximately 80% of the annual world harvest. Kernels in the Nonpareil Marketing Group (NMG) receive prices approximately 30% higher than kernels in other marketing groups. However, no objective standards exist that define kernel shape and appearance boundaries within the NMG. Kernels of NMG almonds were clearly distinguished from kernels of cultivars in the California and Mission Marketing Groups using multivariate analyses. Misclassification of NMG kernels into other marketing groups was dependent on the number of evaluated characters included in the analyses. Almond skin brightness was identified as the single most useful character in distinguishing NMG kernels from kernels in other marketing groups. These results provide methodology for almond breeders in defining the boundaries of kernel variability within the NMG. By providing this methodology, almond breeders now have an objective target against which their new almond selections can be compared.
Technical Abstract: More than 80% of the world’s almonds are grown in California with several dozen almond cultivars available commercially. To facilitate promotion and sale, almond cultivars are categorized into marketing groups based on kernel shape and appearance. Several marketing groups are recognized, with the Nonpareil Marketing Group (NMG) demanding the highest prices. Placement of cultivars into the NMG is historical and no objective standards exist for deciding whether newly developed cultivars belong in the NMG. Principal component analyses (PCA) were used to identify nut and kernel characteristics best separating the four NMG cultivars (Nonpareil, Jeffries, Kapreil, and Milow) from a representative of the California Marketing Group (cultivar Carmel) and the Mission Marketing Group (cultivar Padre). In addition, discriminant analyses were used to determine cultivar misclassification rates between and within the aforementioned marketing groups. A clear distinction of NMG cultivars from representatives of the California and Mission Marketing Groups was evident from a combined PCA using eight of the 19 evaluated characters. Further, NMG kernels were successfully discriminated from kernels representing the California and Mission Marketing Groups with overall kernel misclassification of only 2% using 16 of the 19 evaluated characters. Pellicle luminosity was the most discriminating character, regardless of the character set used in analyses. Results provide an objective classification of NMG almond kernels, clearly distinguishing them from kernels of cultivars representing the California and Mission Marketing Groups.