Measurements of Oleic Acid among Individual Kernels Harvested from Test Plots of Purified Runner and Spanish High Oleic Seed

Abstract

Normal oleic peanuts are often found within commercial lots of high oleic peanuts when sampling among individual kernels. Kernels not meeting high oleic threshold could be true contamination with normal oleic peanuts introduced via poor handling, or kernels not meeting threshold could be immature and not fully expressing the trait. Beyond unintentional mixing, factors contributing to variation in oleic acid concentration in peanut kernels include market type, environment, maturity and/or kernel size; however, the relative influence of these factors, and their interactions, is not quantitatively well understood on the single kernel level. To better understand these factors while simultaneously excluding variation from unintentional mixing, seed from a high oleic spanish cultivar and seed from a high oleic runner cultivar were carefully purified via NIR technology. The purified seed were planted in environmentally controlled test plots to analyze the progeny for oleic acid chemistry. Post flowering, plot sections were either chilled (3.8 -5.0 C below ambient), maintained at ambient or heated (3.8-5.0 C above ambient) in the pod zone to characterize soil temperature effects on oleic acid chemistry development. Fully randomized (4 reps) plots included the purified high oleic spanish and runner cultivars, three soil temperatures, seed maturity (profile board), commercial kernel size classifications, and a late season flower termination protocol. At harvest, the oleic acid concentration of approximately 24,000 individual kernels were measured via NIR technology. Market type, temperature, maturity and size had a significant effect on high oleic chemistry among kernels. Late season flower termination significantly, and positively, influenced high oleic chemistry of runner peanuts, minimized the number of immature kernels not meeting high oleic threshold and resulted in elevated and more consistent distributions in this key chemistry; distributions that were more similar to those of the more botanically determinate, but lower yielding, spanish market type. Data from this study improves our understanding of expected natural variation in high oleic chemistry and suggests late season flower termination of runner peanuts is a viable strategy to maximize high oleic chemistry on the single kernel level.

Measurements of High Oleic Purity in Peanut Lots Using Rapid, Single Kernel Near‐Infrared Reflectance Spectroscopy

“…Furthermore, at equivalent contamination levels, Jumbo peanuts tended to have higher purity values compared with Mediums and No 1s. All other factors being equivalent, larger peanuts tend to be more physiologically mature, and as peanuts mature, oleic acid (%) tends to increase (Davis et al, 2017; Dean et al, 2020; Wang et al, 2018). The differences in average oleic acid content (%) and average purity among grades could be, at least partially, attributed to differing maturities.…”

“…As both conventional and high oleic peanut cultivars are being developed, produced, handled, and shelled, there is opportunity for mixing in the supply chain. Additionally, the exact fatty acid composition of conventional and high oleic peanuts is also dependent on the specific genetics for a cultivar and subsequent seed physiological maturity at harvest, which is largely impacted by agronomic practices and growing environment (Davis et al, 2017; Dean et al, 2020). Given these factors impacting the supply quality and consistency for high oleic peanuts, procurement practices around sampling and testing of potential high oleic lots have evolved.…”

“…Despite the relative speed of single kernel NIR based methods vs. traditional GC measurements, these methods are still limited to practical sample sizes of 10, 50, or 100 kernels when screening potential high oleic lots in the commercial trade. As such, a common purity specification might be 95%, which requires 95 kernels from a random sample of 100 kernels must test high oleic before certifying the bulk lot has acceptable purity (Davis et al, 2017).…”

Enhancing oleic acid content in two commercially released peanut varieties through marker‐assisted backcross breeding

“…With the increase in OLE and decrease in LIN, the O/L ranged from 9.9 to 19.6 among the superior lines of GPBD 4, whereas among the promising lines of G 2–52, it ranged from 11.6 to 17.3. Hence, all these lines with O/L more than 9.0 could be classified as “high oleic” lines (Davis et al., 2017).…”

Building on our Past to Engineer the Future

“…Advances in measuring physical and chemical properties of the peanuts are needed. There are methods to measure properties such as moisture content while the peanuts are still in the shell (Lewis et al, 2013) and oil chemistry of single kernels (Davis et al, 2017) using near-infrared reflectance (NIR). The challenge in developing sensors and instrumentation systems is developing instrumentation robust enough to withstand the rigors of use in the field or in processing lines and at process line speeds.…”