Antonio López-López

Lipolytic activity of the yeast species associated with the fermentation/storage phase of ripe olive processing

Ripe olives account for ca. 30% of the worlds table olive production. Fruits intended for this type of product are preserved in an aqueous solution (acidic water or brine) for several months, where they may undergo a spontaneous fermentation. Enterobacteriaceae and lactic acid bacteria were not detected in the present survey during storage. Thus, the work focused on studying the yeast microflora associated with the ripe olive storage of Manzanilla and Hojiblanca cultivars in acidified brines. A total of 90 yeast isolates were identified by means of molecular methods using RFLP analysis of the 5.8S-ITS rDNA region and sequencing of the D1/D2 domains of the 26S rDNA gene. The two most important species identified in both cultivars were Saccharomyces cerevisiae and Pichia galeiformis, which were present throughout the storage period, while Candida boidinii was detected during the later stages of the process. The species Pichia membranifaciens was detected only in the early stages of the Hojiblanca cultivar. The lipase assays performed with both extracellular and whole cell fractions of the yeast isolates showed that neither of the S. cerevisiae and P. galeiformis species had lipase activity, while the P. membranifaciens isolates showed a weak activity. On the contrary, all C. boidinii isolates gave a strong lipase activity. Change in olive fat acidity was markedly higher in the presence of the yeast population than in sterile storage, indicating that lipases produced by these microorganisms modify the characteristics of the fat in the fruit.

Influence of Ripe Table Olive Processing on Oil Characteristics and Composition As Determined by Chemometrics

The changes in ripe olive fat produced by processing were studied according to cultivars using the general linear model, principal component analysis (PCA), predictive discriminant analysis (DA), and hierarchical clustering. Acidity, peroxide value, K(270), and DeltaK increased during storage. Acidity also increased after sterilization, whereas K(270) decreased after darkening; K(232) showed a progressive decrease during processing. Fatty acids (except C17:0, C18:0, and C24:0), triacylglycerols (except PLLn, OOLn+PoOL, PLL+PoPoO, SOO, and POS+SLS), polar compounds, diacylglycerol, and monoacylglycerols also suffered statistically significant changes during processing. A PCA discriminated between cultivars and, within the same cultivar, among the raw materials from the rest of the treatments. Using fatty acid and triacylglycerol compositions, predictive DA discriminated between cultivars (100% correct), but high discriminant capacity among processing steps (95% correct assignation and 87% in cross-validation) was achieved only with fatty acids. A hierarchical clustering analysis successfully grouped cultivars and processing steps according to overall olive oil composition and quality.

Chemical Composition of Fermented Green Olives: Acidity, Salt, Moisture, Fat, Protein, Ash, Fiber, Sugar, and Polyphenol

Publisher Summary Of fermented green olives, alkali-treated green olives in brine, also known as “Spanish-style green olives” or “pickled green olives,” are the most widely distributed and investigated type of table olive. However, there are other traditional preparations of fermented green olives which are of lesser economic importance in the international market, but highly appreciated by consumers in the Mediterranean region. One of these involves the direct brining of green olives without prior de-bittering with NaOH solution. This preparation is known as “untreated green olives in brine,” “naturally green olives,” “directly brined olives,” or “Sicilian-style green olives.” The taste of untreated green olives is completely different from that of alkali-treated fruits, mainly due to the residual bitterness they retain even after a long period of storage in brine. This olive type (green or turning-color) is one of the bases for many other commercial products, such as “seasoned” olives, which are very popular in Spain. When this preparation is made with natural black olives, it is known as Greek-style table olives, and has been extensively studied. This chapter reviews the two processing types of fermented green olive—that is, Spanish-style and untreated (green or turning-color) olives—with special emphasis on the characteristics (physicochemical parameters, chemical composition) of the final product. It presents a summary of information in the literature regarding the major components in the fresh fruit (raw material).

Effect of bruising on respiration, superficial color, and phenolic changes in fresh Manzanilla olives (Olea europaea pomiformis): Development of treatments to mitigate browning

The aim of the work was to study the postharvest changes in Manzanilla olives and to find treatments to mitigate damages because of bruises. The phenolic content in bruised and unbruised fruits exposed to air always decreased, but the loss in phenols and the respiratory activity were greater in bruised olives; these changes were related to the appearance of brown spots. Immersion of the picked fruits in a cold (8 °C) acidic solution (pH 3), ascorbic acid solution (100 mM), or sodium metabisulfite solution (100 mM) significantly reduced the loss in phenols in olives and led to lighter brown bruised areas. This immersion did not affect the behavior of the fruits during the lye treatment and the subsequent fermentation. In the final product, no influence on the surface color of unbruised olives was observed and there was a significant color improvement in the bruised areas of damaged olives.

Mineral Content and Sensory Characteristics of Gordal Green Table Olives Fermented in Chloride Salt Mixtures

UNLABELLED This work studies the effects of the initial brine concentrations of NaCl, KCl, and CaCl(2) on the mineral content and gustatory and kinaesthetic sensations of fermented green table olives, using a simplex centroid mixture design augmented with interior points. The sodium in the flesh was linearly related to the mixture concentrations while potassium and calcium were linked by quadratic and special cubic models respectively. Acidity, saltiness, hardness, fibrousness, and crunchiness were expressed as linear funtions of the NaCl, KCl, and CaCl(2) initial brine contents but bitterness required quadratic equations. The models can be used to produce table olives with specific mineral contents in the flesh and to predict their corresponding sensory characteristics. PRACTICAL APPLICATION The study provides the industry with models to estimate the Na, K, and Ca mineral contents in the flesh of fermented Gordal green table olives as well as their sensory characteristics as a function of the NaCl, KCl, and CaCl(2) initial compositions in the brining solution. Therefore, the paper provides tools which are able to support the production of commercial presentations which not only satisfy consumer demand for low Na, but are also K and Ca fortified table olive presentations with specific sensory profiles.

Mineral and sensory profile of seasoned cracked olives packed in diverse salt mixtures.

This work studies the effect of packing cracked seasoned olives with NaCl, KCl, and CaCl(2) mixture brines on their mineral nutrients and sensory attributes, using RSM methodology. The Na, K, Ca, and residual natural Mn contents in flesh as well as saltiness, bitterness and fibrousness were significantly related to the initial concentrations of salts in the packing solution. This new process led to table olives with a significantly lower sodium content (about 31%) than the traditional product but fortified in K and Ca. High levels of Na and Ca in the flesh led to high scores of acidity and saltiness (the first descriptor) and bitterness (the second) while the K content was unrelated to any sensory descriptor. The new presentations using moderate proportions of alternative salts will therefore have improved nutritional value and healthier characteristics but only a slightly modified sensory profile.

Comparative study of the use of sarcosine, proline and glycine as acrylamide inhibitors in ripe olive processing

The main purpose of this study was to evaluate the inhibitory effect on acrylamide (AA) formation and the impact on sensory characteristics in ripe olives of three selected amino acids (sarcosine, proline and glycine), which previously showed high AA inhibition rates in an olive model system. Each amino acid was separately added to packing solutions to give 100 or 200 mM at equilibrium, prior to a sterilisation treatment at 121°C. The results showed that sarcosine at 100 mM may be a good candidate for reducing the AA content in ripe olives with a limited effect on sensory characteristics. Studies with a model solution of AA and sarcosine heated at 121°C for 30 min suggested that the main mechanism for the inhibitory effect of sarcosine on AA formation was the Michael reaction. Graphical Abstract

Fermentation in nutrient salt mixtures affects green Spanish-style Manzanilla table olive characteristics

This work studies the effects of the substitution of NaCl with KCl and CaCl2 on the physicochemical, mineral and sensory profile of fermented green Spanish-style Manzanilla olives, using an enlarged centroid mixture design. An increasing presence of CaCl2 in the initial brines improved the colour index, L(∗), b(∗) values, and firmness. The Na in the olives decreased (linearly) while the levels of K and Ca increased (quadratic) as a function of the KCl and CaCl2 concentrations in the initial brines. CaCl2 also improved the retention of Zn and P in the flesh. PLS showed a strong relationship between Ca and bitterness, hardness, fibrousness, crunchiness and saltiness (negative) and allowed for the prediction of sensory attributes (except acid) from the mineral contents in the flesh. Most of the treatments could lead to new green Spanish-style Manzanilla olive presentations with reduced Na and healthier characteristics.

Effect of green Spanish-style processing (Manzanilla and Hojiblanca) on the quality parameters and fatty acid and triacylglycerol compositions of olive fat

This work studies the effect of processing Manzanilla and Hojiblanca olives as green Spanish-style on the quality parameters and fatty acid and triacylglycerol compositions of their oils. Lye treatment reduced the values of most quality parameters while fermentation/packaging increased acidity, K232 and K270. Processing did not cause any systematic effect on fatty acids (FA), triacylglycerols or nutritional fat subclasses but significant differences between cultivars were observed. Principal component analysis (PCA) confirmed that most of the variation among oil characteristics was due to cultivars and only a limited proportion (∼22% and ∼14% variance for FA and triacylglycerols, respectively) to processing. Furthermore, the levels of the quality parameters and fatty acids with restrictions in the legislation were below the limits established in the Commission Implementing Regulation (EU) 1348/2013 for extra virgin olive oil (EVOO), except for C18:3n-3 in Hojiblanca. Therefore, the fat of processed olives was compatible with EVOO.

Pigment, Physicochemical, and Microbiological Changes Related to the Freshness of Cracked Table Olives

The changes in chloroplastic pigments, mineral nutrients, and characteristics related to freshness were studied during storage and packing of cracked seasoned olives. Cracking produced an initial loss in green pigments and color degradation. Later, storage caused a progressive degradation of chlorophylls and carotenoids, with a slower rate in refrigerated fruits (which preserved the greenish tones better), but after packing (and storage at room temperature), the differential effect disappeared and, at the end of the study, all olives showed similar pigment transformations, which were correlated with CIE a* and hue. Processing led to a Na content increase in olive flesh (and Ca and Zn, when added) but marked losses in the other mineral nutrients. Sodium metabisulfite and ZnCl₂ promoted LAB growth while inhibiting yeast, thus enhancing product stability, and erythorbic acid caused yeast growth and firmness deterioration.