Interactions between volatile compounds and the non-volatile matrix occur during oven-cooking, which uses very high temperatures, much higher than restaurant
or home ovens. For example, a key ingredient in good quality traditional pizza is
olive oil, which has been shown to interact with the other ingredient during the short
cooking time (~180 s) required in the wood-fired ovens. Strong differences in the
volatile and phenolic profiles of pizzas cooked using olive oil or other vegetable oils
have been reported (Caporaso et al. 2015a). This demonstrates the importance of the
interaction between volatile compounds and the food matrix during cooking.
Olive oil can also be used as a mixture (dispersion) or emulsions to formulate
products such as sauces or mayonnaise to be used in salads or cold dishes. A body of
research includes the study of the stability (physical and oxidative stability) and shelf
life of products formulated with olive oil. For example, Paraskevopoulou et al.
(2005) reported on the stabilisation methods for emulsions formulated with olive
oil and lemon juice using polysaccharides, while in a subsequent work, the authors
reported on the oxidative stability (Paraskevopoulou et al. 2007). Caporaso et al.
(2016a) used EVOO to formulate low-fat emulsions stabilised by whey protein
isolate and xanthan gum. In a publication that followed, a statistical model was
proposed to describe the physical and chemical stability of the emulsion over storage
(Caporaso et al. 2016b).
9.7.2 Olive Oil in Cooking and Frying
Physical and chemical phenomena have been described when olive oil is used in
cooking, especially VOOs. The polar minor constituents of olive oil, especially the
most reactive phenolic compounds, undergo hydrolysis reactions, but they also exert
their antioxidant properties in such a complex matrix. During cooking, high temperatures are applied: phenolic compounds are hydrophilic substances and tend to
rapidly migrate toward the water phase (Al-Saghir et al. 2004; Andrikopoulos
et al. 2002). Complex phenolic compounds are degraded into simpler molecular
structures, and their antioxidant activity might increase in certain conditions, for
example, when hydroxytyrosol is released, as this compound is often reported to
exert the strongest antioxidant activity among VOO phenolics.
Frying takes place at high temperatures and implies rapid dehydration of the food
being cooked. Pan-frying differs from deep frying, as the former is often carried out
at the beginning of many traditional Mediterranean recipes, to give extra flavour to
the main ingredient. A small amount of olive oil is heated in the pan together with
flavouring vegetable (or animal) ingredients, such as garlic, onion, spices, carrots,
leaks, etc., or chopped meats. This is often used as the “basis” of the recipe, while
further ingredients are added. It can be also used as the sauce for pasta, as many
pasta-based dishes are prepared using an initial pan-frying step. Although an empirical and traditional method that probably arises from observation and creativity of
our predecessors, it has in fact a scientific basis. The oil acts both as a lubricant and
as a “solubiliser” for flavour molecules and potentially bioactive molecules (especially lipophilic compounds) and gives flavour to the dish by itself. This flavour
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241
or home ovens. For example, a key ingredient in good quality traditional pizza is
olive oil, which has been shown to interact with the other ingredient during the short
cooking time (~180 s) required in the wood-fired ovens. Strong differences in the
volatile and phenolic profiles of pizzas cooked using olive oil or other vegetable oils
have been reported (Caporaso et al. 2015a). This demonstrates the importance of the
interaction between volatile compounds and the food matrix during cooking.
Olive oil can also be used as a mixture (dispersion) or emulsions to formulate
products such as sauces or mayonnaise to be used in salads or cold dishes. A body of
research includes the study of the stability (physical and oxidative stability) and shelf
life of products formulated with olive oil. For example, Paraskevopoulou et al.
(2005) reported on the stabilisation methods for emulsions formulated with olive
oil and lemon juice using polysaccharides, while in a subsequent work, the authors
reported on the oxidative stability (Paraskevopoulou et al. 2007). Caporaso et al.
(2016a) used EVOO to formulate low-fat emulsions stabilised by whey protein
isolate and xanthan gum. In a publication that followed, a statistical model was
proposed to describe the physical and chemical stability of the emulsion over storage
(Caporaso et al. 2016b).
9.7.2 Olive Oil in Cooking and Frying
Physical and chemical phenomena have been described when olive oil is used in
cooking, especially VOOs. The polar minor constituents of olive oil, especially the
most reactive phenolic compounds, undergo hydrolysis reactions, but they also exert
their antioxidant properties in such a complex matrix. During cooking, high temperatures are applied: phenolic compounds are hydrophilic substances and tend to
rapidly migrate toward the water phase (Al-Saghir et al. 2004; Andrikopoulos
et al. 2002). Complex phenolic compounds are degraded into simpler molecular
structures, and their antioxidant activity might increase in certain conditions, for
example, when hydroxytyrosol is released, as this compound is often reported to
exert the strongest antioxidant activity among VOO phenolics.
Frying takes place at high temperatures and implies rapid dehydration of the food
being cooked. Pan-frying differs from deep frying, as the former is often carried out
at the beginning of many traditional Mediterranean recipes, to give extra flavour to
the main ingredient. A small amount of olive oil is heated in the pan together with
flavouring vegetable (or animal) ingredients, such as garlic, onion, spices, carrots,
leaks, etc., or chopped meats. This is often used as the “basis” of the recipe, while
further ingredients are added. It can be also used as the sauce for pasta, as many
pasta-based dishes are prepared using an initial pan-frying step. Although an empirical and traditional method that probably arises from observation and creativity of
our predecessors, it has in fact a scientific basis. The oil acts both as a lubricant and
as a “solubiliser” for flavour molecules and potentially bioactive molecules (especially lipophilic compounds) and gives flavour to the dish by itself. This flavour
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