T. Rotunno

Changes in seed yield and oil fatty acid composition of high oleic sunflower (Helianthus annuus L.) hybrids in relation to the sowing date and the water regime

Sunflower is one of the most cultivated oil crops in the world. Recently, high oleic acid cultivars have been developed whose oil has higher oxidative stability and better dietary properties than standard genotypes. In Mediterranean environments where water deficit frequently occurs, early sowing and irrigation are used to overcome environmental constraints due to water scarcity. Since, in the literature, the data on the effect of these agronomic techniques on sunflower oil quality are scarce and contrasting, the aim of this paper was to evaluate the effect of the sowing time and the water regime on seed yield and oil quality of high oleic hybrids in a Mediterranean environment. For this purpose, two high oleic hybrids (Platon and Vyp70) sown in spring at two different dates were cultivated in southern Italy under two water regimes (irrigated and non-irrigated) in 1996 and 1997. Yield and its main components were positively affected by irrigation and by the earlier sowing date. With regard to fatty acid composition, a decrease in oleic and stearic acid and an increase in linoleic and palmitic acid were observed under irrigation. At early sowing, oleic and palmitic acid decreased whereas linoleic and stearic acid increased. The decrease in the oleic/linoleic acid ratio observed at early sowing and under irrigation, suggests a possible role of temperature on the activity of oleate desaturase in the developing seeds.

Fatty acid composition of ewe milk as affected by solar radiation and high ambient temperature.

Forty lactating Comisana ewes were either exposed to or protected from solar radiation and fed either in the morning or afternoon during summer in a Mediterranean climate. Individual milk samples were taken on days 7, 21 and 42 of the study period to determine fatty acid composition by gas chromatography. Exposure to solar radiation resulted in higher proportions of short-chain and saturated fatty acids in milk, primarily because of increased contents of caproic, capric, lauric, myristic and stearic acids (by 3-18%), and decreased contents of oleic, linoleic and linolenic acids (by 2-9%). As a consequence, the long to short chain and the unsaturated to saturated fatty acid ratios were significantly higher by 4 and 13% respectively in the milk of the protected ewes compared with that of the exposed animals. Provision of shade also led to an increase in the 18:0+18:1 to 16:0 ratio, and to a decrease in the 12:0 + 14:0 + 16:0 fatty acid group, which are regarded as reliable indexes of the nutritional property of dietary fat in reducing cholesterol levels in human plasma. Feeding time had little impact on milk fat. Our findings suggest that high ambient temperature may markedly modify the lipid composition of ewe milk and that provision of shade, but not feeding management, can improve the milk fatty acid profile in dairy sheep raised in hot climates.

Effects of intramuscular injection of alpha-tocopheryl acetate on fatty acid profile in lamb liver.

The effects of intramuscularly administrated vitamin E on total lipids, fatty acid profile, and lipid stability to oxidation was investigated in lamb liver. Twenty-four 5-day-old lambs were allotted to 4 groups of 6 each and given respectively 0 (control), 125, 200, 300 mg dl-alpha-tocopheryl acetate weekly from day 5 to 33. alpha-Tocopherol stored in lamb liver at the end of experiment showed linear correlation with the level of injected vitamin E. No effect on total lipids was found. A decrease in the level of liver thiobarbituric-acid reactive substances (TBARS), significantly correlated with liver alpha-tocopherol content, was found in vitamin E groups. The amount of linoleic and linolenic acids significantly increased in the vitamin E groups as compared to control group, and were correlated with the liver alpha-tocopherol content. TBARS were negatively correlated with the concentration of unsaturated fatty acids. Finally, in the liver of the treated groups, vitamin E concentrations in the range 30-50 micrograms/g showed adequate for an efficient protection from peroxidation of membrane lipids, and determined an increase in the unsaturated to saturated fatty acid ratio.