Improving olive oil quality using CO2 evolved from olive pastes during processing
ABSTRACT The effect of blanketing with CO2, naturally evolved during malaxation of olive pastes, on the quality of virgin olive oil was investigated at lab-scale. The O2 depletion was monitored along with CO2 emission to confirm the previously hypothesized accelerated respiration. Malaxation experiments were conducted for 180 min both in sealed (SC) and in the traditional open-to-air conditions to ascertain whether the oil quality was affected by O2 concentration as afforded by CO2 blanketing. The quality of olive oils obtained at different time intervals was monitored by total acidity, peroxide value (PV), specific extinction coefficients K232 and K270, total chlorophyll and total hydrophilic phenols, and HPLC hydrophilic phenols profile. A rapid decrease in oxygen concentration and a simultaneous increase in CO2 concentration were recorded, confirming the accelerated respiration. The oil produced in SC showed a lower PV and K232 coefficient and a higher chlorophyll (10–17 mg/kg) and hydrophilic phenols (110 mg/kg) concentration. No differences in total acidity and K270 coefficient were observed. The hydrophilic phenols profile indicated that, at least for the Frantoio cultivar and an advanced ripeness state, the maximal extraction is generally achieved already after 20 min. Most of the individual hydrophilic phenols have higher concentrations (up to 50%) in SC.
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ABSTRACT: ABSTRACT: This monograph is a critical review of the biological activities that occur during virgin olive oil extraction process. Strategic choices of plant engineering systems and of processing technologies should be made to condition the enzymatic activities, in order to modulate the nutritional and the sensory quality of the product towards the consumer expectations. "Modulation" of the product quality properties has the main aim to predetermine the quantity and the quality of two classes of substances: polyphenols and volatile compounds responsible of VOO nutritional and sensory characteristics. In the first section, a systematic analysis of the literature has been carried out to investigate the main olive enzymatic activities involved in the complex biotransformation that occurs during the mechanical extraction process. In the second section, a critical and interpretative discussion of the influence of each step of the extraction process on the polyphenols and the volatile compounds has been performed. The effect of the different mechanical devices that are part of the extraction process is analyzed and recommendations, strategies, and possible avenues for future researches are suggested. PRACTICAL APPLICATION: In the field of virgin olive oil industry, time and energy should be spent on developing innovative processing plants and equipment able to better modulate the physical parameters that influence endogenous olive enzyme activities, such as temperature, time, amounts of processing water and oxygen. This review paper can be a useful resource to design and develop innovative equipment by offering an exhaustive analysis of mechanical effects of industrial devices and biological effects of endogenous enzymes on the sensory and nutritional properties of virgin olive oil.Comprehensive Reviews in Food Science and Food Safety 03/2014; 13(2). · 5.05 Impact Factor
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ABSTRACT: Highlights ► Malaxation has been recognized as one of the most critical points in the production of virgin olive oil. ► More than 100 studies have been carried out to investigate malaxing conditions (time, temperature and atmosphere). ► The automatic control of the malaxation of oil out of olives is still an open field. ► Electronic noses and tongues are also promising techniques in olive oil extraction process control.Trends in Food Science & Technology. 05/2012; 25(1):13–23.
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ABSTRACT: The main goal of this study was to investigate the effects of moderate saline water irrigation in the “Chemlali” olive cultivar grown in Sfax, an arid region of Tunisia, on the composition and quality of the resultant virgin olive oil in comparison to a control plot grown under rain-fed conditions. Free acidity, peroxide value, specific ultraviolet absorbance (K232, K270), fatty acid composition, induction time, total polyphenol and total chlorophyll contents were determined and reported. The irrigation did not affect free acidity and peroxide value. Whereas, specific ultraviolet absorbance (K232, K270), fatty acid composition, induction time, total polyphenol and total chlorophyll contents were affected by irrigation. Rain-fed virgin olive oils showed a statistically significant higher content of oleic and linoleic acids. Virgin olive oils extracted from moderate saline water irrigated trees had higher contents of palmitic, palmitoleic, stearic and linolenic acids and a longer shelf-life. A positive correlation was noted between polyphenol content and oxidative stability.PRACTICAL APPLICATIONSOlive trees are quite widespread in the south of Tunisia. They grow in semi-arid environments. It is a species with high resistance to drought. However, irrigation allows productivity to increase in olive growing areas where rainfall is scarce. Irrigation is a determinant parameter for olive oil quality. In fact, high olive oil quality can not be obtained from olive fruit suffering from a high degree of water stress. The main purposes of this paper are to investigate the effects of moderate saline water on the commercial quality, the fatty acid composition, and the induction time, total polyphenol and total chlorophyll contents of “Chemlali” virgin olive oil in Tunisia.Journal of Food Quality 04/2010; 33(2):228 - 247. · 0.76 Impact Factor