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The effects of temperature and O2 availability on quality attributes and nutritional value of oil in four walnut (Juglans regia L.) cultivars (Chandler, Hartley, Franquette, and Ioli) were investigated. Dried kernels, all of initial high quality, were packaged under air or N2 or CO2 and stored at 1 °C or 20 °C for 12 months. Results showed that the saturated fatty acids (SFA) myristic, palmitic, stearic, and arachidic remained stable during storage, whereas the unsaturated palmitoleic, oleic (OL), gondoic, linoleic (LL) and linolenic (LN) decreased, with the stable vaccenic being the exception. Rancidity, assessed as free fatty acids and peroxide value, increased after 12 months, and rancidity evolution found to be correlated with LL and LN, but not with OL. In all cultivars, low temperature and N2 or CO2 prevented additively the fatty acid (FA) losses and rancidity increases. The best results were obtained in walnuts stored at 1 °C under N2 or CO2, while storage at 20 °C under air led to the greatest product deterioration. However, storage at 20 °C under N2 or CO2 and at 1 °C under air showed intermediate results and similar among them. The cultivar affected the kernel oil content and FA profile initially, as well as, the FA decreases and rancidity development during storage. The omega‐6/omega‐3 ratio largely depended on cultivar and was affected by storage conditions. Overall, the storability of the studied cultivars in descending order was Chandler > Hartley, Franquette > Ioli. Practical applications: Storage at 1 °C under N2 or CO2 for 12 months retained the peroxide value (PV) lower than 3 meq O2 kg−1 oil and the free fatty acids (FFA) up to 0.6%, cut‐off values for acceptable walnuts, as suggested by the walnut industry in California. Storage at 20 °C under N2 or CO2 increased the PV value up to 10 meq O2 kg−1 oil, being the upper acceptable limit according to panel tests in studies. For energy savings, the 12‐months storage at 20 °C with low O2 availability can substitute the storage at 1 °C under air. Rancidity development and nutritional value related to fatty acids largely depended on cultivar. Thus, the cultivar factor should also be considered for storage purposes and according to the destination markets. Effects of temperature and packaging atmosphere on rancidity and nutritional value related to oil composition in stored dried kernels of walnut (Juglans regia L.) cultivars. The present results are summarized in the bi‐plot (combination of score and load plots) of Principal Component Analysis. Each color corresponds to each cultivar. Rhombuses, circles, squares, and triangles, corresponding to different storage conditions, indicate the position of each walnut sample in score plot. Daggers indicate the position of major fatty acids and indicators of rancidity in load plot.

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Relationships among alpha-farnesene synthesis and oxidation, ethylene production and perception, antioxidative enzyme activities, and superficial scald development in fruit of three commercial apple cultivars were investigated at the biochemical and gene transcriptional levels. Scald-susceptible Cortland and Law Rome and scald-resistant Idared apples were untreated or treated with the ethylene action inhibitor 1-methylcyclopropene (1-MCP) and stored for up to 25 weeks at 0.5 degrees C. Separate blushed (red) and unblushed (green) peel tissue samples were taken at harvest and after 2, 4, 6, 10, 15, 20, and 25 weeks of storage. Large increases in peel tissue concentrations of alpha-farnesene and its conjugated trienol (CTol) oxidation products occurred in untreated Cortland and Law Rome and were about 4-9-fold greater than those in Idared. In both Cortland and Law Rome, accumulation of CTols in green peel was nearly twice that in red peel. 1-MCP treatment delayed and attenuated alpha-farnesene and CTol accumulation in each cultivar. Activities of peroxidase (POX) and catalase (CAT) were lower in red peel than in green peel, with the exception of CAT in Law Rome, whereas no effects of 1-MCP on enzyme activities were detected except for Cortland. In control fruit, internal ethylene concentrations (IECs) increased during the first 4-6 weeks to reach highest levels in Cortland, intermediate levels in Law Rome, and low levels in Idared. In 1-MCP-treated fruit, IECs increased gradually to modest levels by 25 weeks in Cortland and Law Rome but were almost nil in Idared. Expression patterns of the alpha-farnesene synthase gene MdAFS1, the ethylene receptor gene MdERS1, and the ethylene biosynthetic genes MdACS1 and MdACO1 were generally in accord with the patterns of alpha-farnesene and ethylene production. In particular, MdAFS1 and MdACS1 showed similar patterns of expression in each cultivar. Among the controls, transcript levels increased more rapidly in Cortland and Law Rome than in Idared during the first few weeks of storage. In 1-MCP-treated fruit, transcript abundance in Cortland and Law Rome rose to untreated control levels after 10-15 weeks but remained low in Idared. Scald symptoms were restricted to unblushed skin, and the incidence in controls after 25 weeks was nearly 100% in Cortland and Law Rome compared with 1% in Idared. 1-MCP treatment reduced scald incidence to 14, 3, and 0% in Cortland, Law Rome, and Idared, respectively. Overall, the results support the proposed role of CTols in scald induction and indicate that alpha-farnesene synthesis is tightly regulated by ethylene. However, gene transcription alone does not account for the big differences in ethylene and alpha-farnesene production in Cortland, Law Rome, and Idared apples.