Oil Quality and Sugar Content of Peanuts (Arachis hypogaea) Grown in Argentina: Their Relationship with Climatic Variables and Seed Yield CRISTIANO CASINI, † JULIO L. DARDANELLI,* ,† MARI ÄA J. MARTI ÄNEZ, † MO Ä NICA BALZARINI, § CARMEN S. BORGOGNO, § AND MIRTHA NASSETTA # INTA Estacio ´n Experimental Manfredi, 5988 Manfredi, Co ´rdoba, Argentina; Facultad de Ciencias Agropecuarias, Avenida Valparaı ´so s/n, Ciudad Universitaria, 5000 Co ´rdoba, Argentina; and Unidad Ceprocor, Agencia Co ´rdoba Ciencia, Arenales 230, 5000 Co ´rdoba, Argentina The ratio of oleic to linoleic acids (O/L) and the tocopherol content are important features in determining peanut (Arachis hypogaea) seed shelf life. Soluble carbohydrates are known to be important precursors in roasted peanut flavor. The chemical qualities of Argentine grain are different from those of other countries, but no previous studies that associate grain quality and environmental parameters have been performed. Relationships were determined between O/L, tocopherol and sugar contents, and variations in temperature and rainfall during the grain filling period of Florman INTA peanuts. Dry seed yield was used as another explanatory variable. Multiple regression procedure gave mean temperature (positive coefficient) and total precipitation (negative coefficient) as the explanatory variables for variations in O/L. Total precipitation and dry seed yield (both negative coefficients) were found to be predictor variables for tocopherol and sugar contents. Total precipitation was an explanatory variable included in all of the linear regression models obtained in this study. KEYWORDS: Peanut; sugars; O/L ratio; tocopherol; Arachis hypogaea INTRODUCTION Along with the United States (U.S.) and China, Argentina is one of the major exporters of peanuts for human consumption, supplying an average of 245000 ton/year -1 during the period 1996-2000 (1). In 1998 peanut exports from Argentina were the highest in the world (2). Most of the peanuts produced in Argentina (98%) are concentrated in the semiarid region of Co ´rdoba province, delimited by the parallels 31° 30′ and 33° 30′ S and the meridians 63° 00′ W and 64° 30′ W. Florman INTA is a runner market-type, which accounts for 85% of the total peanut production in Argentina. Peanut storage quality depends on the relative proportion of saturated and unsaturated fatty acids that make up the oil. The degree of unsaturation is inversely proportional to the quality of the oil (e.g., oxidative rancidity increases with increased levels of the polyunsaturated fatty acids that cause associated odors and flavors) (3). The ratio of oleic to linoleic acids (O/L) has commonly been used as a means of predicting shelf life and oil stability. A higher O/L trait confers better stability and longer shelf life (4, 5). The other factor contributing to shelf life is tocopherol content, which acts as a lipid-soluble natural anti- oxidant (6). Tocopherols stabilize polyunsaturated fatty acids within lipid bilayers by protecting them from lipoxygenase attack (7). Greater sugar content is correlated with a more intense sweet taste (8). The region of Argentina where most peanuts are grown has uniform environmental conditions, as seen in the mean values of seasonal radiation, mean temperature, rainfall regime, and soil characteristics. For the period from November to March, mean temperature and total precipitation ranges in this region are 21.8-22.5 °C and 591-629 mm, respectively. However, some variability in compositional quality has been found in the Florman INTA variety. The variation coefficients across the region found in previous studies were 9% for O/L (9, 10), 10% for tocopherols, and 28% for sugars (10). Such a variation might be related to changes in environmental conditions caused by different planting dates, the usual range of which is October 25th to November 28th. Studies have shown considerable compositional and quantita- tive changes in the lipids and fatty acids of groundnut seeds during the seed growth period to maturity, that is, between 15 and 80 days after the onset of the seed filling period (11). Usually, at the farmer level, the date of harvest is available but the date of the beginning seed stage is unknown. Simulation models previously calibrated, such as CROPGRO-Peanut (12), could be a useful tool to estimate the date of this reproductive stage. The aim of this work is to analyze the relationship among O/L, tocopherol and sugar contents, and variations in temper- † INTA Estacio ´n Experimental Manfredi. § Facultad de Ciencias Agropecuarias. # Unidad Ceprocor. 10.1021/jf030183j CCC: $25.00 © xxxx American Chemical Society PAGE EST: 4.4 Published on Web 00/00/0000