Effect of harvest period and storage conditions of Olive fruit on Olive oil quality
1992
Ben-Stati, M.
Fruits of the Greek olive cultivar Koroneiki were harvested on three different dates (December 3, 1991, January 1, 1992, January 21, 1992) and stored under different storage conditions (aerobic conditions at room temperature, anaerobic conditions at room temperature, 2 percent salt, 4 percent salt, aerobic conditions at 5oC, anaerobic conditions at 5oC) for several periods (1, 2, 3, 4, weeks for room temperature storage and 2, 4, 6, weeks for cold storage). Oil content as a percentage of dry weight and defatted dry matter were determined. Oil press extracted by experimental olive oil mill was analysed: Refractive index, Iodine value, free fatty acid, Peroxide value, specific absorbency and total phenols and polyphenols content were determined for all samples. The percentage fatty acid composition at harvest date and after four weeks of storage was also determined for fruits harvested on January 21, 1992. Early harvested fruits showed better storage behaviour than late harvested ones. These fruits can be stored for three weeks without significant increase in oil acidity and risk of oxidation. The oil from early harvested fruits had low degree of hydrolytic and oxidative deterioration and a high phenol content. The differences between early and late harvest dates decreased after three weeks of olives storage. Salt treatments decreased acidity but not as anaerobic conditions at room temperature of cold storage. Anaerobic conditions decreased acidity in both cold and room temperature storage, indicating that air is involved in increased acidity by promoting micro-organism development and activating hydrolyzing enzymes. Cold storage and anaerobic conditions at room temperature resulted in lower degree of oxidation of oil than other treatments. The unsaturated: saturated fatty acid ratio increased with storage time of olive fruit in all treatments and most in cold storage.
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