Giacomo Squeo

Influence of calcium carbonate on extraction yield and quality of extra virgin oil from olive (Olea europaea L. cv. Coratina)

The aim of the research was to evaluate the effect of calcium carbonate (1%, 2%, and 4% of addition) at two different particle sizes (2.7μm and 5.7μm), added at the beginning of the malaxation phase, on both the extraction yield and the quality of oil obtained from Coratina olives at different ripening index. The results showed that calcium carbonate significantly increased the extraction yield of olive oil, more than affecting chemical indices. In particular, for less ripened olives, 1-2% of larger particle size calcium carbonate addiction determined a significant increase of the extraction effectiveness, ranging from 4.0 to 4.9%, while more ripened olives required higher amounts of coadjuvant (2-4% when using the larger particle size and 4% when using the smaller one), with a significant increase of the extraction yield up to 5%. Moreover, an increase of pungent perception was observed in some cases when adding calcium carbonate to more ripened olives.

Effect of infusion of spices into the oil vs. combined malaxation of olive paste and spices on quality of naturally flavoured virgin olive oils

Olive oil flavouring with aromatic plants and spices is a traditional practice in Mediterranean gastronomy. The aim of this work was to compare the influence of two different flavouring techniques (infusion of spices into the oil vs. combined malaxation of olives paste and spices) on chemical and sensory quality of flavoured olive oil. In particular, oxidative and hydrolytic degradation (by routine and non-conventional analyses), phenolic profiles (by HPLC), volatile compounds (by SPME-GC/MS), antioxidant activity, and sensory properties (by a trained panel and by consumers) of the oils were evaluated. The obtained results evidenced that the malaxation method was more effective in extracting the phenolic compounds, with a significantly lower level of hydrolysis of secoiridoids. As a consequence, antioxidant activity was significantly lower in the oils obtained by infusion, which were characterized by a higher extent of the oxidative degradation. The volatile compounds were not significantly influenced by changing the flavouring method, apart for sulfur compounds that were more abundant in the oils obtained by the combined malaxation method. From a sensory point of view, more intense bitter and pungent tastes were perceived when the infusion method was adopted.

Has the use of talc an effect on yield and extra virgin olive oil quality

The maximization of both extraction yield and extra virgin olive oil quality during olive processing are the main objectives of the olive oil industry. As regards extraction yield, it can be improved by both acting on time/temperature of malaxation and using physical coadjuvants. It is well known that, generally, increasing temperature of malaxation gives an increase in oil extraction yield due to a reduction in oily phase viscosity; however, high malaxation temperature can compromise the nutritional and health values of extra virgin olive oil, leading to undesirable effects such as accelerated oxidative process and loss of volatile compounds responsible for oil flavor and fragrance. The addition of physical coadjuvants in olive oil processing during the malaxation phase, not excluded by EC regulations owing to its exclusively physical action, is well known to promote the breakdown of oil/water emulsions and consequently make oil extraction easier, thus increasing the yield. Among physical coadjuvants, micronized natural talc is used for olive oil processing above all for Spanish and Italian olive cultivars. The quality of extra virgin olive oil depends on numerous variables such as olive cultivar, ripeness degree and quality, machines utilized for processing, oil storage conditions, etc. However, the coadjuvants utilized in olive processing can also influence virgin olive oil characteristics. The literature highlights an increase in oil yield by micronized natural talc addition during olive processing, whereas no clear trend was observed as regards the chemical, nutritional and sensory characteristics of extra virgin olive oil. Although an increase in oil stability was reported, no effect of talc was found on the evolution of virgin olive oil quality indices during storage.

Influence of the feed pipe position of an industrial scale two-phase decanter on extraction efficiency and chemical-sensory characteristics of virgin olive oil: Decanter feeding impact on extraction efficiency and olive oil quality

BACKGROUND Nowadays, olive oil extraction is basically achieved by means of two-phase decanters, which allow a reduction of water consumption and the leaching of phenolic compounds. Despite this, most of the working settings derive from studies carried out on three-phase decanters. Hence, the aim of the present study was to assess the influence of two-phase decanter feed pipe position (FP) on the extraction efficiency and chemical-sensory characteristics of virgin olive oil. Three different positions were considered: at 825 mm (FP1), 610 mm (FP2) and 520 mm (FP3) from the outlet of the oily phase. RESULTS Position FP3 allowed the highest oil recovery (up to 10%), the lowest percentage of oil in the olive pomace and, in general, a regular trend in terms of oil extraction efficiency. However, the oily must that came out of the decanter was not completely clean in terms of residual content of solid sediment and water. The feeding position partially affected the profile of antioxidant compounds. CONCLUSION In two-phase decanters, loading the olive paste close to the outlet of the oily phase is recommended to increase the extraction efficiency without jeopardizing the chemical-sensory characteristics of virgin olive oil.

CALCIUM CARBONATE EFFECT ON ALKYL ESTERS AND ENZYMATIC ACTIVITIES DURING OLIVE PROCESSING

The effect of coadjuvants during olive oil processing on the oxidative enzymes and the content of fatty acid alkyl esters (FAAE) has been investigated. Two Italian olive cultivars, at different ripening degree, were processed immediately after harvesting or after 5 and 12 days of storage. The results highlighted a general decrease of FAAE and a significant increase in the PPO and POD activities due to the coadjuvant use. The increased oxidases activity could lead to a reduction of oils phenolic compounds.

Antioxidant activity, tocopherols and polyphenols of acornoil obtained from Quercus species grown in Algeria

Among the unusual vegetable fats, acorn oil has interesting nutritional and functional properties. Few studies are present in literature on acorn oil characterization and antioxidant activity evaluation while no studies are present regarding the analysis of the phenolic profile. The present study aims at investigating the content of hydrophilic and lipophilic phenolic compounds and pigments, as well as antioxidant properties and quality of the oil extracted from three Quercus species grown in Algeria. Oil yield, expressed as dry weight, was in the range 7.05-8.40%. Tocopherols contents were remarkable for the three species (539-676 mg kg-1), with (β + γ)-tocopherols being the most abundant. Oils had also significant amounts of carotenoids (42-66 mg kg-1) and similar polyphenol patterns, but with a wide quantitative variability between species (195-436 mg kg-1). Twenty phenolic compounds were detected, 12 of which were tentatively identified. All of them were hydrolysable tannins derivatives (gallotannin or ellagitannin). Oils methanolic extracts had remarkable antioxidant activity; up to 3.34 and 3.79 μmol TE g-1 oil (DPPH and ABTS test, respectively). Quercus oil is a potential source of natural antioxidants, and it could be used as a new functional oil.