**2.2. Natural olives**

348 Olive Germplasm – The Olive Cultivation, Table Olive and Olive Oil Industry in Italy

(Figure 2).

harvested at the green stage of ripening and, once they arrive at the processing plant, they are graded, since only fruits of more than 19 mm in diameter are used. The selected olives are put into plastic vessels and covered with 2.5-3.5 °Bè NaOH solution (1.7-2.4%), depending on the fruit ripeness and size. These vessels have 220 L total capacity, and are filled with around 140 kg of fruits. Eight hours after the lye treatment begins, 6-7 kg of grinded salt is added to each container, and the olives are kept in this "alkaline brine" for 8- 10 days. Salting is performed by placing the grinded salt over the "press-fruit" of each barrel

**Figure 2.** Addition of grinded salt directly on the "press-fruit" at the surface of the barrel

temperature maintained between 4 °C and 7 °C, or in packing solutions.

The sodium chloride in contact with the liquid is slowly dissolved and is distributed by gravity in the whole volume of the container. The salt traditionally used in this type of procedure is sea salt coming from the saltworks of Trapani. It is particularly rich in trace elements such as K, Mg, Ca, Fe and I, unlike the rock salt composed almost exclusively of NaCl. In this environment, the olives are softened quickly highlighting a deep green color. When the barrel is opened, the lye/salt brine is drained and the olives are washed to remove excess lye. A mild washing step, carried out before marketing, does not totally eliminate the lye, whose "soapy" taste is appreciated by the consumers of these olives. Under ambient storage conditions the Castelvetrano olives have a shelf-life of only a few months, especially under hot conditions. Deteriorated olives lose colour and develop off-odours. As this olive style is a seasonal product, long-term storage is not required. Future research, however, may refine the process and include steps for long-term storage under refrigeration, with the

*(*photograph by A. Cappello from Lanza & Poiana*,* 2011).

The "natural olives", according to the "Trade Standard Applying to Table Olives" (IOC, 2004) are "green olives, olives turning color or black olives placed directly in brine in which they undergo complete or partial fermentation, preserved or not by the addition of acidifying agents". The most important industrial preparation for natural black olives takes the name "Greek-style" because it is traditionally practiced in Greece utilizing *Conservolea* cv. (Balatsouras, 1990).

### *2.2.1. Natural turning colour olives*

Italy has a long tradition in producing "natural turning colour olives". In this process the olives are directly brined in 8-10% of sodium chloride. The brine stimulates the microbial activity for fermentation and reduces the bitterness of the oleuropein. Fermentation of these olives takes a long time because diffusion of soluble components through the epidermis, in fruits not treated with alkali, is slow. A diverse microbiota grows in these brines, although yeasts are the microorganisms always present throughout the process. *Enterobacteriaceae* can be found during the first 7-15 days, but they disappear as the brine characteristics do not support their growth. The presence of lactic acid bacteria depends on the salt concentration and the polyphenol content of the variety used. The traditional brining is carried out under anaerobic conditions. However, an aerobic method can be applied, using a central column in the fermenter through which air is bubbled. This system changes the ratio between fermentative and oxidative yeasts, and a final product with better quality is attained (Garcia Garcia *et al*., 1985 ; Garrido Fernández *et al*., 1997). The colour fades during the process, but it is corrected by aerating the olives for two or three days; sometimes they are treated with 0.1% ferrous gluconate or lactate to make them deep black. Lastly, the olives are selected and

packed in barrels or in varnished cans, which are filled with 8% fresh brine. They are popular because of their slightly bitter taste and aroma. When the bitterness has been sufficiently weakened the fruit can be marketed. To reduce the debittering phase, several researches have evaluated the use of selected oleuropeinolytic lactic acid bacteria (LAB) as starter cultures in Greek-style olive processing. *Lactobacillus plantarum (*Ciafardini *et al*., 1994; Marsilio *et al*., 1996; Marsilio & Lanza, 1998; Marsilio *et al*., 2005; Panagou *et al*., 2008) and *Lactobacillus pentosus*  (Panagou *et al*., 2003; Panagou *et al*., 2008; Servili *et al*., 2006), in addition to developing a fast growth and a good acidifying capacity even in the presence of high concentrations of salt (brine), were able to grow in the presence of phenolic compounds (known for their antimicrobial action) and, thanks to the marked oleuropeinolytic activity, degraded the oleuropein in no-bitter compounds, reducing thus considerably the time of debittering.

Nutritional and Sensory Quality of Table Olives 351

then covered with water. The bowl is left to rest for 48 hours, then everything is drained and rinsed; the next step is to let the olives steep for 24 hours in a container with salt and bay leaves. After that the olives are drained and laid out on wood or stone board and squashed with a wood pin, until the seeds come away. Once squashed, the olives are gathered and placed in a glass container, they are pressed with the hands and dressed with chili pepper and other spices and condiments and covered with extra virgin olive oil. During the fermentation of cracked green olives, the predominant microorganisms are yeasts while lactic acid bacteria are not detected. The main role of yeasts in the processing of fermented olives, is associated with the production of alcohols, ethyl acetate, acetaldehyde and organic acids, compounds that are relevant for the development of taste and aroma and the preservation characteristics of

The Scabecciu olives are a traditional preparation typical of Sardegna region. The ripe olives of *Tonda di Cagliari* and *Pizz'e Carroga* varieties are engraved in three points, put in brine for about 3 days, washed with water and blanched in vinegar-water and then dried in the sun. Finally, they are fried with garlic and parsley and placed in oil. After about 1 month of

In Basilicata region, olives are prepared with an ancient and traditional method, Ferrandina method, which name derives from the small city Ferrandina, near Matera, where olive trees of *Olea europaea* L. *Majatica* cv. are cultivated (Savastano, 1937; Di Gioia, 1959; Cucurachi *et al*., 1971). The olives are hand-harvested at the black stage of ripening at the end of November-early December. Initially the olives are blanched in water at 90°C for 3 min to make the skin more permeable and facilitate the osmotic processes. After blanching, the olives are salted with grinded NaCl (10:1 w/w) for 3 days and finally they are placed in single layer and oven-dried in an air-oven at 50 °C for 36 hours until the humidity is around 8 % and Aw around 0.7. This product is ready to eat in 1 week. The first two steps of the process (blanching and salting) contribute to fruit debittering; the second and the final steps (salting and oven-drying) result in water loss for better preservation of the product. This trade preparation is in accordance with the "Trade Standard Applying to Table Olives" (IOC, 2004) as "dehydrated and/or shrivelled black olives", black olives that have undergone or not mild alkaline treatment, preserved in brine or partially dehydrated in dry salt and/or by heating or by any other technological process. Today, olives from cv. Majatica are almost entirely destined to the production of oil. The production of oven-dried black olives by Ferrandina-style is in drastic decline and manufacturers are few. The product is prevalently exported in the USA and not all olives sold in the Italian market as oven-dried olives

Textural changes occurring in oven-dried olive -tissues during each processing step were visualized by scanning electron microscope, texture analyzer, analysis of cell wall

this fermented food (Alves *et al*., 2012; Arroyo-Lopez *et al*., 2008).

preparation they can be consumed as appetizer.

**2.3. Oven-dried black olives by Ferrandina-style** 

*2.2.4. "Scabecciu" olives* 

originate from cv. *Majatica*.
