Pedro Garcia

 The use of manganese (Mn) salts in various steps of the processing of ripe olives of the Manzanilla cultivar can increase their oxidation rate and produce darker olives. The best results were obtained by adding a Mn concentration of 40 mg/l to the storage brine and allowing a period of contact of at least 15 days. Good results were also obtained when using a Mn concentration of 100–250 mg/l in a “desalting” step before darkening, as well as variable periods of contact and temperatures. When Mn was added to the washing waters after any of the lye treatments of the darkening step, especially the first one, the effect was also appreciable, although varying degrees of Mn residues in the flesh were found. Addition of Mn to the storage brine and application of the usual darkening process produced more uniform and darker ripe olives with Mn residue levels at below 30 mg/kg, which is approximately 15% of the recommended daily intake for this metal. Results suggest that this cation, recognized as GRAS in the USA, may be used as a catalyst in the darkening of ripe olives if authorized as a processing aid.

Restrictions on the discharge of chloride in wastewater streams have recently increased, and processors of black ripe olives have to look for alternative storage systems to the traditional brines. Ripe olives of the Hojiblanca variety were stored under aerobic and anaerobic conditions in industrial underground tanks for one year. The aerobic systems assayed with or without NaCl produced a continuous consumption of sugars as they diffused from the fruits to the surrounding liquid. At the same time sugars accumulated in the liquid for months when anaerobic conditions were employed and a high concentration of acetic acid was used. In the end, glucose was consumed with time as well and, in addition to yeasts, acetic acid and lactic acid bacteria grew in the cover solutions. The assessment of olives stored under the different systems and processed as black ripe olives revealed that the traditional aerobic brines gave rise to darker and firmer fruits. However, olive industries must eliminate chlorides from their waste streams. Promising new storage systems were (i) anaerobic preservation of olives in water with an initially high concentration of acetic acid, and (ii) aerobic preservation in water with an initially low concentration of acetic acid. Both systems produced a good quality product, free of microbial spoilage and organoleptic defects.

The distribution of sorbic and benzoic acids in the different phases of table olives was studied. To a large extent, these preservatives accumulated in the oil phase of fruits stored in acid conditions, as well as in juice and other tissue components. Thus, around 20–30% of the benzoic acid in olives was found in the juice phase, 30–50% in the oil phase and 30–40% in the rest of the olive flesh. Experiments carried out with black ripe olives revealed that an increase in pH of the medium gave rise to a decrease in the absorption phenomenon in whole olives and in the oil phase. As a consequence of this effect, benzoic acid could be leached from stored black ripe olives during the darkening process, although the calcium content of fruits greatly influenced the diffusion phenomenon. The results obtained in this study are important for future legal limitations of these preservatives in table olives and inhibition capacity of them in commercial table olives.

There is increasing interest in olive polyphenols because of their biological properties as well as their contribution to the color, taste, and shelf life of olive products. However, some of these compounds remain unidentified. It has been shown that hydroxytyrosol 4-β-d-...

... Series Editors Randy Goebel, University of Alberta, Edmonton, Canada Jörg Siekmann, University of Saarland, Saarbrücken, Germany Wolfgang Wahlster, DFKI and ... We are grateful to the tutorial lecturers for the brilliant talks: Tim Oates, with Sourav Mukherjee, Colin de la ...

Page 1. 21 Ingeniería y Competitividad, Volumen 11, No. 1, p. 21 - 36 (2009) § Gloria I. Alvarez* , José Ruiz**, Pedro García** ... La escasez de trabajos se puede explicar en la mayor complejidad de este enfoque con respecto a la inferencia de DFAs. ...

... Series Editors Randy Goebel, University of Alberta, Edmonton, Canada Jörg Siekmann, University of Saarland, Saarbrücken, Germany Wolfgang Wahlster, DFKI and ... We are grateful to the tutorial lecturers for the brilliant talks: Tim Oates, with Sourav Mukherjee, Colin de la ...