Postharvest heat treatment of apples maintains fruit firmness and reduces decay during storage. Four days at 38C are beneficial, but 1 or 2 days are detrimental. The cellular basis of these effects may involve changes in cell wall and membrane lipid metabolism. Lipids from hypodermal tissue of `Golden Delicious' apples were analyzed after 0, 1, 2, or 4 days at 38C. Major lipids included phospholipids (PL), free sterols (FS), steryl glycosides (SG), and cerebrosides (CB). Galactolipids (GL) were minor components. PL content fell ?10% after 1 day at 38C, was unchanged after 2 days, and began to rise again after 4 days. PL class composition did not change with heating, but fatty-acid unsaturation declined throughout. FS and CB content and composition changed little, whereas SG content cropped by ≈20% over 4 days. GL fell ≈50% during 1 day at 38C, with no change at days 2 or 4. A burst of PL catabolism followed by recovery of synthesis may in part explain the different effects of 1-, 2-, or 4-day heat treatments. GL loss (in plastids) may be related to the effect of heat on fruit color (yellowing).
Bruce D. Whitaker, Joshua D. Klein, and William S. Conway
Dana F. Faubion and Adel A. Kader
California-grown `Hass' avocado fruit were stored at 5C, in air or a controlled atmosphere (CA) of 2% oxygen and 5% carbon dioxide. Fruit were evaluated at 0, 2, 4, 6, 8, 10, and 12 weeks, both immediately upon removal from storage and after ripening at 20C. Severe chilling injury (flesh browning) developed in the airstored fruit after 6 weeks, while only moderate symptoms were observed in CA-stored avocado fruit after 12 weeks. Lipid peroxidation breakdown products increased during storage and ripening in both air and CA treatments. Sterols, steryl esters, steryl glycosides, glycolipids, and phospholipids were analyzed. Quantity of acylated steryl glycoside in ripe fruit changed from 34 nmoles initially, to 51 or 27 nmoles after 6 weeks at 5C in air or CA, respectively. Glycolipid fatty acid unsaturation in air-stored fruit decreased with the development of chilling injury. Fatty acid unsaturation in phospholipids (phosphatidylinositol, phosphatidylcholine, phosphatidylglycerol, and phosphatidylethanolamine) of air-stored avocados decreased with the development of chilling injury. CA storage delayed the development of chilling injury and the loss of fatty acid unsaturation.
G.A. Picchioni, A.E. Watada, W.S. Conway, B.D. Whitaker, and C.E. Sams
Postharvest CaCl2 pressure infiltration improves firmness and storage quality of apples but is still in the experimental stages. Its effectiveness could be increased if we had a better understanding of how Ca affects the tissue at the cellular level. `Golden Delicious' fruit were harvested from a commercial orchard and were pressure-infiltrated with CaCl2 (0%, 2%, or 4% w/v), stored for 6 months at 0C, and then for 7 days at 20C. Between harvest and the end of storage at 20C, the net breakdown of galactolipids and phospholipids decreased with increasing CaCl2 in infiltration solutions. During 0C storage, CaCl2-infiltrated fruit maintained greater concentrations of conjugated sterol lipids, and these lipid classes are thought to be closely associated with the plasma membrane. As membrane lipid alterations are viewed as a central factor in the senescence of fruits, Ca (from postharvest infiltration) may serve a major role in regulating fruit quality losses through its interactions with cell membranes.
Álvaro Fernández-Cuesta, Ossama Kodad, Rafel Socias i Company, and Leonardo Velasco
Phytosterols or plant sterols are natural constituents of plants. They resemble mammalian cholesterol, both in their chemical structure and their biological function ( Piironen et al., 2000 ). Phytosterols regulate the fluidity and permeability of
Maria J. Berenguer, Paul M. Vossen, Stephen R. Grattan, Joseph H. Connell, and Vito S. Polito
A comparative study was conducted to evaluate the influence of seven different levels of irrigation applied to `Arbequina I-18' olive (Olea europaea L.) trees grown in a super-high-density orchard (1,656 trees/ha) in the Sacramento Valley of California. Water was applied differentially by drip irrigation at rates of 15%, 25%, 40%, 57%, 71%, 89%, and 107% evapotranspiration (ETc) in 2002, and 28%, 33%, 55%, 74%, 93%, 117%, and 140% ETc in 2003. Each treatment was replicated three times. Olives were harvested on two different dates each year from each of 21 plots. Three of four harvest dates showed a decrease in maturity index with increasing irrigation levels. Oils were made from olive samples collected from each plot and analyzed for oil quality parameters. Total polyphenol levels and oxidative stability decreased as the trees received more water, especially for the three lowest irrigation treatment levels in 2002, but few differences were noted between treatments in 2003 when all the trees were irrigated more heavily. Average oxidative stability was correlated very closely with total polyphenol content with r 2 = 0.98 in 2002 and 0.94 in 2003. In 2002, free fatty acid levels increased and peroxide levels were unchanged, but in 2003, free fatty acid levels were unchanged and peroxide levels decreased in treatments receiving more water. Saturated fatty acids did not significantly change in 2002, due to tree irrigation level. The mono-unsaturated fatty acid levels and oleic–linoleic relationship declined while poly-unsaturated fatty acid levels increased in 2002 with increased irrigation. In 2003, there was no notable difference in the ratio of mono to poly unsaturated fatty acid levels. The individual fatty acid most consistently affected by more irrigation water was stearic, which decreased in both years. Total sterol content (mg·kg–1), percentages of cholesterol and erythrodiol were significantly influenced by tree irrigation levels, but increased in one year and either decreased or were unchanged the next. Oil sensory properties of fruitiness, bitterness, and pungency all declined in oils made from trees receiving more water. The lowest irrigation levels produced oils that were characterized by excessive bitterness, very high pungency, and woody, herbaceous flavors. Intermediate irrigation levels (33% to 40% ETc) produced oils with balance, complexity, and characteristic artichoke, grass, green apple, and some ripe fruit flavors. Higher irrigation levels lowered oil extractability and produced relatively bland oils with significantly less fruitiness and almost no bitterness or pungency.
Carmen Mena, Alejandra Z. González, Raúl Olivero-David, and María Ángeles Pérez-Jiménez
/91 ( EEC, 1991 ). Sterol composition. The determination of sterol composition was carried out by GC according to the official method described in European Commission Regulation 2568/91 ( EEC, 1991 ). Quantification was made by addition of an internal
Diana M. Cheng, Gad G. Yousef, and Mary Ann Lila
hydroxylation steps, impacting carbon allocation early in the phytoecdysteroid pathway such as during phytosterol biosynthesis. The phytosterol biosynthetic network has been well investigated and therefore affords molecular tools and specific sterol biosynthesis
Janet C. Cole, Robert O. Brown, and Mark E. Payton
Ancymidol and uniconazole are plant growth regulators that slow plant growth by inhibiting sterol and gibberellin biosynthesis ( Henry, 1985 ; Shive and Sisler, 1976 ). These growth regulators have been shown to restrict height of several
Maurizio Micheli, Daniel Fernandes da Silva, Daniela Farinelli, Graziana Agate, Rafael Pio, and Franco Famiani
, especially, as a pesticide ( Lokanadhan et al., 2012 ). Triglycerides make up about 97.7% of the oil, with oleic, linoleic, stearic, and palmitic fatty acids being the main ones ( Djibril et al., 2015 ). The unsaponifiable fraction contains sterols and
Huimin Zhang, Hongguang Yan, Cuixiang Lu, Hui Lin, and Quan Li
generated by sterol, glycerol resin, etc., and δ 2.4–0.8 signals represent aliphatic hydrogens. Fig. 1. 1 H-NMR spectra of sweet cherry tree leaves under rain-shelter cultivation. Fig. 2. 1 H-NMR spectra of sweet cherry tree leaves under open