Characterization of Virgin Olive Oils with Two Kinds of ‘Frostbitten Olives’ Sensory Defect

Abstract

The frost of olives on the tree due to drops of temperature can produce sensory defects in virgin olive oil (VOO). Temperature changes can be abrupt with freeze-thaw cycles or gradual, and they produce sensory and chemical variations in the oil. This study has analyzed the quality parameters (free fatty acids, peroxide value, UV absorption, and fatty acid ethyl esters) and phenols of VOOs described with the 'frostbitten olives' sensory defect. The phenol profiles allowed grouping these VOOs into two types. One of them, characterized with "soapy" and "strawberry-like" aroma descriptors, had higher values of 1-acetoxypinoresinol, pinoresinol, and aldehydic form of the ligstroside aglycon. The other one, characterized with "wood" and "humidity" descriptors, had higher concentrations of luteolin and apigenin. Most VOOs (75%) from the first group, associated with abrupt drops of temperature, have concentration of phenols higher than the value established by the health claim on olive oil polyphenols approved by the European Commission.

Genotype‐by‐environment effect on bioactive compounds in strawberry (Fragaria x ananassa Duch.)

“…In the flavone group, sinesetin and luteolin content levels varied at different altitudes for seven and four varieties, respectively. These differences could be attributed to the effect of UV‐radiation and sunshine duration for most of the varieties, except ‘Sveva’, for which the dominant factor appears to be temperature, probably as a result of the cold stress response of this variety, which is more adapted to Mediterranean climate compared to the other varieties considered. Ellagitannins appeared to be higher in samples from the valley floor and Verona and, when a correlation with environmental variables was present, with UV‐radiation or sunshine duration, except for ‘Marmolada’ and ‘Sveva’.…”

Olive Fruit Refrigeration during Prolonged Storage Preserves the Quality of Virgin Olive Oil Extracted Therefrom

“…Romero et al [ 27 ] characterized the phenolic profile of Spanish olive oils (Cornicabra, Hojiblanca, and Picual cultivars) with “frostbitten olives” sensory defect and found that the concentrations of all the investigated groups of phenols decreased in defective oils, except secoiridoids. The authors [ 27 ] explained these differences by considering the action of enzymes that are affected by frost; physical damage of olive fruits by ice crystals formed during freezing leads to cellular destruction, allowing phenolic substrates to mix with polyphenol oxidase (PPO), which degraded them. In this study, lower concentrations of the majority of phenols, even secoiridoids, were found in oils obtained from the fruits frozen at −20 °C in comparison to control oils.…”

“…It is probable that the cold storage conditions slowed down the rate of enzymatic and biochemical reactions, which lead to the degradation of these particular phenols, as noticed in RT oils, and at the same time avoided the negative effects caused by freezing, observed in the oils obtained from the fruits stored at −20 • C. These findings are in agreement with the results of Hachicha Hbaieb et al [9], who found more similar phenolic profiles of the oils obtained from Arbequina fruits stored at 4 • C and the freshly harvested ones, in comparison to the oil obtained from fruits stored at 20 • C, which was explained by the similar endogenous enzyme activity patterns detected in the fruits of the former treatments. Romero et al [27] characterized the phenolic profile of Spanish olive oils (Cornicabra, Hojiblanca, and Picual cultivars) with "frostbitten olives" sensory defect and found that the concentrations of all the investigated groups of phenols decreased in defective oils, except secoiridoids. The authors [27] explained these differences by considering the action of enzymes that are affected by frost; physical damage of olive fruits by ice crystals formed during freezing leads to cellular destruction, allowing phenolic substrates to mix with polyphenol oxidase (PPO), which degraded them.…”

“…On the other hand, low temperatures may cause physiological damage of the fruit [ 24 ] since ice crystals formed during frozen storage may break down the cell structure and at the same time allow the contact between various enzymes and substrates that could affect VOO quality [ 25 , 26 ]. Very low temperatures during olive fruits development and harvest, with related cycles of freezing and defrosting of fruits on the tree, are known to cause biochemical changes, which significantly modify its volatile compound and phenolic profiles [ 22 ] and could induce the development of the “frostbitten olives” sensory defect in olive oil [ 27 ].…”

Development of high resolution mass spectrometric methods for the investigation of food authenticity

“…Liquid Chromatography (LC) remains the technique of choice for the qualitative and quantitative determination of several phenolic compounds in EVOOs/VOOs [58], coupled to different detectors, such as UV/Vis [41,67,68], Diode Array (DAD) [41,45,52,69,70] or Mass Spectrometers (MS) [57,[70][71][72]. Low and high molecular weight phenolic compounds can be separated by LC, due to the wide number of possible combinations between the mobile and the stationary phases.…”