Vertical centrifugation of virgin olive oil under inert gas
ABSTRACT Virgin olive oil vertical centrifugation under inert gas (IVC) was compared with conventional vertical centrifugation in contact with air (CVC). IVC gives a strong reduction of the oil oxygenation in terms of
reduced dissolved oxygen concentration and oxidative indexes (peroxide values and K232). Minor
compounds (chlorophyll and total phenols) and volatile compounds were not affected by the treatment.
Practical applications: A technical implementation of inertized vertical separators appears a practicable
solution to preserve virgin olive oil quality traits. This can be easily implemented both by the mill
owner with homemade adjustment of the existing machines and by plant industrial manufacturers.
SourceAvailable from: Giovanni Carlo Di Renzo[Show abstract] [Hide abstract]
ABSTRACT: Olive oil extraction is mainly carried out using continuous extraction by decanter centrifuge with efficiency of approximately 80–90%. After centrifugal extraction, olive oil is generally cleaned using a vertical disc stack centrifuge separator, which is suspected of being the major cause of decreased final olive oil quality. Experiments were carried out at industrial scale to compare the olive oil properties after improved processes of sedimentation (Sedoil) or centrifugation (Cenoil) with respect to raw olive oil obtained at the decanter exit (Control). Peroxide, polyphenol, chlorophyll, carotenoid, turbidity and K232 average values were significantly different between Sedoil and Cenoil, which confirmed that the use of disc stack centrifuges represents an important source of oxidative reactions. Analysis showed that storage time dramatically affects the oxidation level of the olive oil. All parameters used to monitor the oxidation level (i.e., free acidity, peroxide value and K232) increased after 180 d of storage, and the content of natural antioxidants and pigments decreased as expected. The residual presence of water during long-term storage represented the most important source of oxidation, and an effective cleaning operation is necessary to preserve oil quality during its storage life. The analyses performed using 1H and 13C NMR showed that Sedoil was more similar in composition to Control than to Cenoil. The use of sedimentation plant allows the employment of the disk stack centrifuge to be reduced improving both energy saving and the quality of clean olive oil.Biosystems Engineering 06/2014; 122:99–114. DOI:10.1016/j.biosystemseng.2014.04.007 · 1.37 Impact Factor
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ABSTRACT: The purpose of this study is to evaluate the effects of the mechanical components on pits and oil droplet fractionation. The olive pastes obtained using four different crushing systems were compared. Analyses of the pit particle size distribution and oil drop aggregation were performed. The analysis of the experimental data shows that different crushing machines produce different pit and oil drop fragmentation, and the trends confirm that increased pit fragmentation corresponds to increased droplet fragmentation. Therefore, the results confirm that the partial de-pitter and hammer crusher yielded the greatest enhancement in emulsification of oil droplets, and the stone mill and disc crusher yielded the greatest aggregation of oil droplets.Practical application: The practical application of this work includes understanding the effects of four different crushers on oil drops and pit fragmentation. The experimental data could be useful to define the best malaxation time and to gain a better understanding of the minor components distribution in olive oil. The results obtained could be used to construct a guideline for the design and sizing of crushing machines.European Journal of Lipid Science and Technology 02/2015; DOI:10.1002/ejlt.201400485 · 2.03 Impact Factor
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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). DOI:10.1111/1541-4337.12054 · 3.54 Impact Factor