*2.1.1. Treated green olives in brine by Sevillan-style*

This method is also known as Sevillan or Spanish-style and it is one of the most common and oldest methods for Italian green table olives (Tavanti, 1819). To obtain the "treated green olives in brine", the fruits are debittered with NaOH aqueous solution ranging from 2.0% to 3.5%, mainly depending on the variety and ripeness of the olives. The alkaline treatment performs the function of hydrolyzing the compound principally responsible for the bitter taste (oleuropein). The lye solution completely covers the fruits and the olives remain in this solution until the lye has penetrated between 2/3 and 3/4 of the distance between the skin and the pit. To verify a correct lye treatment, olives are cut with a particularly sharp blade such as razor blade or scalpel near the pit, checking the surface after air exposition. After alkaline treatment, the olives are washed with potable water. The sequence of washings is the following:

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

**Figure 1.** Regional distribution of Italian table olive production.

**2.1. Treated olives** 

The main Italian table olive preparations are the following:

and preserved or not by the addition of acidifying agents".

*2.1.1. Treated green olives in brine by Sevillan-style* 

The "treated olives", according to "Trade Standard Applying to Table Olives" (IOC, 2004) are "green olives, olives turning color or black olives that have undergone alkaline treatment, then packed in brine in which they undergo complete or partial fermentation,

This method is also known as Sevillan or Spanish-style and it is one of the most common and oldest methods for Italian green table olives (Tavanti, 1819). To obtain the "treated green olives in brine", the fruits are debittered with NaOH aqueous solution ranging from 2.0% to 3.5%, mainly depending on the variety and ripeness of the olives. The alkaline treatment performs the function of hydrolyzing the compound principally responsible for the bitter taste (oleuropein). The lye solution completely covers the fruits and the olives remain in this solution until the lye has penetrated between 2/3 and 3/4 of the distance


After water-washings to eliminate the residual lye, olives are covered with a sodium chloride solution (brine) and left to develop a spontaneous lactic fermentation. Initial brine concentrations are 8-10% NaCl but rapidly drop to 5% due to the high content of interchangeable water in the olives. A spontaneous fermentation starts as soon as the olives are placed in brine. After alkaline treatment, the pH of olive flesh reaches the value of 11.0- 13.0 down to the value of 8.0-9.0 after the repeated washings. In this broth culture, a complex and variable microbiota grows. Reducing sugars and glucosides, the basic sources of carbon needed in the development of lactobacilli and other microrganisms, pass from olive flesh to the brine, where they are used by heterofermentative or homofermentative microrganisms to produce lactic acid. In the first phase of fermentation, when Gramnegative bacteria prevail, the pH ranges from 8.0-9.0 to about 6.0. This low pH promotes the growth of lactic acid bacteria that are aciduric with optimal growth between pH 5.5 and 5.8. At the end of lactic fermentation, the pH reaches values <4.0 and acidity increases, ensuring thus the preservation of the product. The lactic fermentation ends with the exhaustion of available carbohydrates (glucose from glucosides and reducing sugars). Several researches have been carried out to evaluate the technological functionality of selected lactic acid bacteria or enterococci in Spanish-style green olive processing. *Enterococcus casseliflavus* and *Lactobacillus pentosus* (de Castro *et al*., 2002; Sánchez *et al*., 2001) have been proposed as starter cultures to accelerate lactic acid formation at pH 9 (immediately after washings). In this case, obviously, the strain used as starter is not necessarily oleuropeinolytic because lye has just demolished the bitter glucoside. The importance of this type of starter is to reduce the lag phase and the risk of spoilage (Bevilacqua *et al*., 2010; Ruiz-Barba *et al*., 1994; Leal-Sanchez *et al.,* 2003). As a result of ill-treatment alkali set or poorly conducted, the tissues of the fruit may also undergo profound changes in structural and nutritional constituents (Marsilio & Lanza, 1995).

#### *2.1.2. Sweet green olives by Castelvetrano-style*

This is a production method used in Sicilia, almost exclusively in the Castelvetrano district using the *Nocellara del Belice* cultivar. The product is mainly consumed in central and southern Italy (Cappello & Poiana, 2005; Lanza & Poiana, 2011). The olives are hand-

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).

Nutritional and Sensory Quality of Table Olives 349

*2.1.3. Green olives by lime-and-ash treatment* 

**2.2. Natural olives** 

cv. (Balatsouras, 1990).

*2.2.1. Natural turning colour olives* 

In some Italian regions (Puglia, Campania, Lazio and Calabria), olives are prepared with an ancient and traditional method that includes a debittering phase obtained using a lime-ash mixture, preparing these treated green olives by mixing CaO (lime) with olive wood ash and adding water to a paste, leaving submerged the green olives for some hours at room temperature. The ratio of lime and ash is different (1:4, 1:8, 1:10, etc) and depends on the cultivar and shape of the fruit. The action of lime-ash is similar to that of NaOH. After alkaline treatment, the olives are washed with potable water. The sequence of washings is similar to the sequence previously described for the treated green olives by Sevillan-style. It is possible to eat these olives right after the debittering treatment or after brining. In this case, after the washing step, olives were placed in an initial brine solution of NaCl (8% w/v), where a spontaneous fermentation takes place. NaCl concentration is carefully monitored during this phase. The brine concentration decreases quickly as a consequence of the osmotic phenomena between the brine and the fruits from 8% to about 5% in 48-72 h. For this reason after 4-5 days from brining, grinded salt is added to the brine to restore the initial

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*

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

concentration. After 1-2 months of fermentation olives are ready to eat.

**Figure 2.** Addition of grinded salt directly on the "press-fruit" at the surface of the barrel *(*photograph by A. Cappello from Lanza & Poiana*,* 2011).

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