Material Balance of Olive Components in Virgin Olive Oil Extraction Processing

Abstract

Processing of olive fruits using a three-phase extraction system for the production of virgin olive oil was analyzed to clarify the material balance of olive fruit components, i.e., oil, water, carbohydrates, proteins, minerals and polyphenols. The estimated total olive material balance based on mass flow indicated a final oil extraction yield of around 83.3%, with an initial olive fruit mass flow of 500 kg/h. The remaining oil was discharged as a byproduct, mainly in olive cake (8.9%) and olive mill water (7.8%). The material balance of carbohydrates showed that the majority were discharged in olive cake (73.3 kg/h) and olive mill water (27.7 kg/h). The material balance of polyphenols, the most important functional compounds in olives, was determined because of their importance to olive oil chemical stability. Results showed an increase in polyphenols content during malaxation operation (17.6%), which was correlated with several enzymatic reactions directly reflected in the composition of virgin olive oil.Keywords: olive oil, operation, material balance, saccharides, polyphenols, enzymatic activities IntroductionVirgin olive oil (VOO) is the foremost edible oil in the Mediterranean region diet. VOO is produced from the whole olive fruits of Olea europaea, a traditional crop in the Mediterranean region. The fruit is an oval-shaped drupe, consisting essentially of the following three parts: epicarp, mesocarp, and endocarp. The epicarp (skin) and the mesocarp (pulp) account for about 65 _ 83%of the total weight, while the endocarp (stone) may vary from 13% to 30%. The average chemical composition of olive fruit is 50%water, 1.5% protein, 22% oil, 24% carbohydrates, and 1.5% minerals. Olive fruit is also high in polyphenols, in the range of 1% of fresh weight (IOOC, 2002).VOO is produced via industrial extraction, which represents one of the most traditional food processing activities in the Mediterranean region (Vlyssides et al., 2004). The process involves only mechanical operations, which can be sub-divided in two main parts: (1) preparation of a homogeneous paste based on crushing and malaxing operations, and (2) oil extraction. The objective of any oil extraction method is to extract as much oil as possible without altering the quality.The following three types of extraction systems are currently in use: (1) a system of hydraulic presses used to press the olive paste;(2) a continuous three-phase system in which the oil is separated from the mass by centrifugation; and (3) a continuous two-phase system in which centrifugation is used to separate olive oil from a mixture of olive cake and olive mill water in one phase, which is characterized by a pasty consistency and termed two-phase olive cake.Currently, the three-phase extraction system is the most commonly used method for VOO extraction in Tunisia. The flow diagram comprises four main operations: fruit cleaning; preparation of the paste (crushing, malaxation); separation of solid and liquid phases; and finally, the clarification of the collected VOO.Fruit cl...

A performance comparison of olive oil mill wastewater enzymatic treatments

“…3). This could be explained by the presence of intrinsic hydrolytic enzymes in olive fruits (β-glucosidases, esterase) which were released from olive cell during olive oil extraction as it was reported in the literature (Briante et al, 2002;Dammak et al, 2015b). The experimental value of β-glucosidase activity detected in crude OOMW sample was found to be around 80 U/mL.…”

“…verbascoside and hydroxytyrosol glucoside) contained hydroxytyrosol moieties in their chemical structure, which could be released by the action of β-glucosidase and esterase ( Fig. 1) (Dammak et al, 2015b;Hamza et al, 2012;Khoufi et al, 2011;Boskou et al, 2006). β-glucosidases (EC 3.2.1.21) catalyze the hydrolysis of carbohydrates and break the bonds present in glycosides, such as verbascoside and hydroxytyrosol glucoside, releasing hydroxytyrosol or glucose (Bhatia et al, 2002).…”

Assessment of the antioxidant and antibacterial activities of different olive processing wastewaters

“…Previous studies on the degradation of polyphenols in its original OMW matrix during the extraction process and upon storage revealed their poor stability due to the complex and reactive nature of OMW, where oxidation, condensation, polymerization, and enzymatic hydrolysis can all potentially take place [ 36 , 37 ]. It has been reported previously that OMW from semi-modern three-phase process has higher phenolic content than OMW from modern three-phase process [ 19 ].…”

The impact of vertical centrifugation on olive oil quality

“…Therefore, a hydrophobic compound has a K value greater than unity, while the hydrophilic molecules have lower values (Clodoveo et al, ). For example, Dammak et al () calculated the K values during vertical centrifugations for oleuropein ranged from 0.003 to 0.006, while it ranged from 0.68 to 0.77 for hydroxytyrosol. Thus, the added tap water could reduce the hydrophilic phenol content.…”