Unfiltered olive has aspects of both a
suspension and an
emulsion. Plant material from olive drupes is suspended in oil due to lack of the filtering step, along with microdroplets of vegetative and non-vegetative
water in small amounts (0.1–0.3%) forming in a water-oil emulsion. Unfiltered olive oil initially has higher levels of
phenolics that form a complex polyphenol-
protein complex. This complex interacts within the suspension/emulsion system and contributes to the formation and maintenance of the physicochemical properties of this oil. However, the presence of water in unfiltered oil leads to a more rapid hydrolysis of these water-associated phenolics, and also to hydrolysis of the
triglycerides in the oil, and
enzymes present in particles of olive fruit and pit and
pathogens such as
yeasts can accelerate the rate of degradation of the quality of the oil and increase the oil
free acidity. The overall effect of filtration on olive oil durability is controversial, with different studies coming to different conclusions, and likely also depends on the specific systems used to filter the oil. The main phenolics found in olive oil are
secoiridoids,
hydroxytyrosol, and
tyrosol, along with
caffeic,
vanillic,
p-coumaric,
syringic and
p-hydroxy benzoic acids,
3-hydroxyphenylethanol and
3,4-dihydroxyphenylethanol. == Natural cloudiness versus low-temperature cloudiness ==