Chlorophyll pigment composition in table olives (cv. Gordal) with green staining alteration.

Metallochlorophyllic complexes of copper are present in green table olives, showing the alteration known as green staining. They were formed stepwise in such a way that new metallochlorophyll derivatives were detected as the fruits became more altered. Cu-15-glyoxylic acid pheophytin a was the first compound formed, followed in order by Cu-pheophytin a, Cu-15-glyoxylic acid pheophytin b, Cu-15-formyl-pheophytin a, and Cu-pyropheophytin a. Pigment analysis in fruits classified according to the surface area affected by green staining showed a progressive increase in the concentration of all copper complexes with the course of the alteration. The metallochlorophyll derivatives of copper were present both in the part of the fruit affected by the alteration and in the remainder part, although the amount was significantly greater in the former. On the other hand, not all the copper present in the fruits was accessible for the formation of such compounds, since the concentration of copper complexes found in olives with the maximum degree of alteration observed did not exceed 20% of the total copper of the fruit.     

Detection of the color adulteration of green table olives with copper chlorophyllin complexes (E-141ii colorant)

The present work proposes a procedure for the detection of the color adulteration of green table olives with E-141ii colorant. Addition of this colorant to table olives to obtain a green permanent color in the product is a fraudulent practice, because the FDA allows its use only in citrus-based dry beverage mixes and European Union regulations do not permit the addition of colorants to table olives. The method consists of a pigment extraction in liquid phase and subsequent analysis by HPLC-DAD. The fraudulent addition of E-141ii is determined from the detection in fruit and/or packing solution, of peaks identified as copper chlorophyllin complexes, which are compounds completely foreign to the natural pigment profile of green table olives. The proposed methodology allows controlling the color quality of green table olives.     

Changes in the volatile composition of Spanish-style green table olives induced by pasteurisation treatment

Thermal treatment of pasteurisation is the most widely used stabilisation method for packed green table olives. In the present work, the influence of pasteurisation on the composition of volatile compounds in packed Spanish-style green table olives was studied. To this aim, two thermal processes (P1 = 85 °C for 7 min; P2 = 85 °C for 15 min) were evaluated by comparing the contents of volatile compounds in pasteurised olives with those in unpasteurised olives. Volatiles were analysed, both in olive juice and cover brine, by means of headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS). Both pasteurisation treatments caused significant increases in diverse ethyl and methyl esters and in volatile compounds derived from several chemical reactions (lipid oxidation, Maillard reaction, degradation of carotenoids). Significant differences between samples subjected to P1 and P2 were only found for 1-octen-3-ol, pentanal and 6-methyl-5-hepten-2-one in olive juice.     

Evidence for the involvement of lipoxygenase in the oxidative processes associated with the appearance of green staining alteration in the Gordal olive

Lipoxygenase (LOX) activity and chloroplast pigment content were monitored during fruit growth in Gordal and Manzanilla olive varieties (Olea europaea regalis and Olea europaea pomiformis respectively). At all growth stages, LOX activity was greater in Gordal than in Manzanilla, and in both varieties, enzymatic activity peaks coincided with the maximum presence of oxidised chlorophyll pigments in the fruits. The higher lipid peroxidation potential measured directly in vitro and indirectly in vivo in the Gordal variety and its correspondence with higher contents of oxidised catabolites of chlorophyll suggested a greater tendency and sensitivity of this variety to oxidative processes. This could also explain the high organelle disorganisation levels reached during industrial processing of the fruit, allowing the formation of copper–chlorophyll complexes associated with the green staining alteration that affects Gordal olives. Copyright © 2003 Society of Chemical Industry     

Use of molecular methods for the identification of yeast associated with table olives

A molecular approach is used for the identification of yeast isolated from table olives. Our results validate those obtained in the past by the classical biochemical methodology. Yeast were isolated from both aerobically and anaerobically processed black table olives and also from canned seasoned green table olives. Molecular identification methodology used included restriction pattern analysis of both PCR-amplified 5.8S rRNA gene and internal transcribed spacers ITS(1) and ITS(2). For some species, sequence analysis of the 26S rRNA gene was necessary. These techniques allowed the identification of three yeast species (Issatchenkia occidentalis, Geotrichum candidum and Hanseniaspora guilliermondii) which had not been described previously in table olives. Saccharomyces cerevisiae and Candida boidinii were the most frequent species in green seasoned olives and processed black olives, respectively. The molecular study of total DNA variability among the S. cerevisiae strains isolated indicates a quite heterogeneous population, with at least four different restriction patterns.     

Volatile profile of Spanish-style green table olives prepared from different cultivars grown at different locations

The volatile profiles of Spanish-style green table olives elaborated with Manzanilla, Gordal and Hojiblanca cultivars grown at different locations in Spain were established by solid phase micro-extraction (SPME) and gas chromatography coupled to mass spectrometry (GC–MS). A total of 102 volatile compounds were identified, belonging to distinct chemical classes, and 20 of them are reported for the first time in table olives. The headspace profile was predominated by alcohols and phenols, followed by acids and esters, whereas the relative amounts of the remaining classes were quite lower (< 5% in general). The principal compounds characterizing the headspace for most samples were p-creosol, phenylethyl alcohol, acetic acid, ethanol, benzyl alcohol, ethyl acetate, and (Z)-3-hexen-1-ol. Significant differences in the proportions of volatile compounds between samples from the Gordal cultivar and those from Manzanilla and Hojiblanca cultivars were detected and statistically visualized by principal component analysis (PCA). Among all the identified compounds, only (E)-2-decenal showed significant differences between the three cultivars without being significantly affected by locations where the fruits were grown.     

Chlorophylls in olive and in olive oil: chemistry and occurrences

The chlorophylls are responsible for the characteristic green color of the olive fruits and their products. Virgin olive oil (VOO) is obtained from processing olives only by mechanical and physical means under conditions ensuring that the natural characteristics of the fruit composition are maintained as far as possible. In terms of the total chlorophyll content of oil, the extraction process entails a loss of chlorophyll of up to 80%. Many factors, both agronomical and technological, can affect the presence of green pigments in VOO. The analysis of green pigments in olives and/or oil requires an initial phase of extraction of these compounds from the solid and fluid matrix, followed by the selective separation and subsequent identification of the different components of the chlorophyll fraction. The aim of this review article is to summarize and critically analyze the available information about chlorophylls in VOO.     

Inhibitors of lactic acid fermentation in Spanish-style green olive brines of the Manzanilla variety

Frequently, a delay or lack of lactic acid fermentation occurs during the processing of Spanish-style green olives, in particular of the Manzanilla variety. Many variables can affect the progress of fermentation such as temperature, nutrients, salt concentration, antimicrobials in brines, and others. In this study, it was demonstrated that an inappropriate alkaline treatment (low NaOH strength and insufficient alkali penetration) allowed for the presence of several antimicrobial compounds in brines, which inhibited the growth of Lactobacillus pentosus. These substances were the dialdehydic form of decarboxymethyl elenolic acid either free or linked to hydroxytyrosol and an isomer of oleoside 11-methyl ester. Olive brines, from olives treated with a NaOH solution of low concentration up to 1/2 the distance to the pit, contained these antimicrobials, and no lactic acid fermentation took place in them. By contrast, a more intense alkaline treatment (2/3 lye depth penetration) gave rise to an abundant growth of lactic acid bacteria without any antimicrobial in brines. Therefore, the precise cause of stuck fermentation in Manzanilla olive brines was demonstrated for the first time and this finding will contribute to better understand the table olive fermentation process.     

Effect of partial substitution of sodium with potassium chloride in the fermenting brine on organoleptic characteristics and bioactive molecules occurrence in table olives debittered using Spanish and Castelvetrano methods

This research was aimed at testing whether the partial substitution of NaCl with KCl (50 or 75% relative substitution) in the fermenting brine of green table Nocellara del Belice olives debittered using two used method (Spanish and Castelvetrano) affected the presence of nutritionally relevant molecules (tocopherols, carotenoids, squalene, phenolic compounds) or the organoleptic characteristics of the table‐ready product. Results support the effectiveness of NaCl partial substitution by potassium chloride for olive processing, with the advantage of a significant decrease in the amount of sodium in the end product. The presence of the main bioactive molecules remained substantially unchanged, but KCl was associated with an increase in bitterness in both debittering methods. However, bitter properties (bitter, persistence and aftertaste) of olives obtained through the modification of Castelvetrano method still remained below those debittered with the classic Spanish method preserving, for such olives, the characteristic of ‘sweet olives’.     

Chemometric characterisation of the fats released during the conditioning processes of table olives

This work deals with the characterisation of five fat types released during the conditioning process of table olives, pitting green olives (PGF), pitting ripe olives (PRF), pitting/stuffing green olives with vegetable origin products (PSGVF) and pitting/stuffing green olives with animal origin materials (PSGAF) along with the fat collected at the end of the factory sewer (WF). The parameters analysed included: acidity, peroxide value, spectrophotometric measurements (K₂₃₂, K₂₇₀ and ΔK), fatty acid composition of the raw material and the neutral fat, triacylglycerol composition of the neutral fat as well as the proportion and composition of the polar fraction. A chemometric analysis of specific groups of compounds was able to establish differences among the types of fats; the overall analysis showed two major groups: PGF, PRF and PSGVF were only moderately degraded, and PSGAF and WF were highly degraded. The information provided can help industries and authorities to handle these residues properly.     

Stability of monosodium glutamate in green table olives and pickled cucumbers as a function of packing conditions and storage time

The effects of different packing conditions and storage times on the stability of monosodium glutamate (MSG) added to two different fermented vegetables (Spanish-type green table olives and pickled cucumbers) were studied. Factors such as packaging material (glass bottle versus plastic pouch), heat treatment (pasteurisation versus non-pasteurisation), and the presence or not of a preservative compound (potassium sorbate) were considered. The MSG content of pickled cucumbers was stable for up to 1 year of storage in all packing conditions studied. The MSG content also remained stable in pasteurised green table olives. On the contrary, MSG was extensively degraded (>75% degradation) after 54 weeks of storage in unpasteurised green olives with a higher degradation rate in glass bottles compared with plastic pouches. In the presence of potassium sorbate, MSG was also considerably degraded in olives packed in plastic pouches (>50% degradation), but hardly degraded in glass bottles. The results indicate that MSG degradation in olives is due to the action of both lactic acid bacteria and yeasts, with the formation of γ-aminobutyric acid as the major end-product.     

Influence of fruit ripeness and salt concentration on the microbial processing of Arbequina table olives

Arbequina table olives are processed as “naturally green olives”, they are directly placed in brine and fermentation starts spontaneously. Olives are harvested just before they change to ‘turning colour’. Different salt concentrations are used depending on the producer. The aim of the study was to evaluate how (i) the ripeness of the olive when it is harvested and (ii) the salt concentration of the brine influence the different microorganism populations in brine during the fermentation of Arbequina table olives.The results showed that the Enterobacteriaceae population lasted longer in black and turning colour olives than in green olives, whereas the growth of lactic acid bacteria was delayed in green olives. A higher salt concentration favoured the elimination of Enterobacteriaceae and hindered yeast growth. The main yeast species identified were Pichia anomala, Candida sorbosa and Candida boidinii, while Lactobacillus plantarum was the only lactic acid bacteria species involved in the process. In a sensory test, panellists preferred green olives and were not able to tell the laboratory-scale processed olives from a commercial sample, nor could they distinguish green olives from different brines.     

Antioxidant Effect of Natural Table Olives Phenolic Extract Against Oxidative Stress and Membrane Damage in Enterocyte‐Like Cells

The phenolic fraction of a naturally fermented cultivar of table olives, “Tonda di Cagliari,” was investigated for the ability to protect Caco‐2 cells against oxidative stress and membrane damage induced by tert‐butyl hydroperoxyde (TBH). TBH exposure resulted in an alteration of cellular redox status, with an increase in reactive oxygen species (ROS) and a decrease in reduced glutathione (GSH) level. A loss of the epithelial integrity, as indicated by the decrease of the transepithelial electrical resistance value, was also observed over time, together with an intense lipid peroxidation process. The olives phenolic extract significantly counteracted ROS generation and subsequent alteration of monolayer integrity and membrane oxidative damage. The protective action of the extract is likely due to the scavenging ability of its main components, as hydroxytyrosol, oleuropein, and verbascoside among the secoiridoids and derivatives. Since olives phenolic compounds concentrate in the intestinal lumen, they may be a useful tool in the prevention of intestinal disorders related to oxidative damage.     

HPLC–MS analysis of the green food colorant sodium copper chlorophyllin

Five commercial samples of sodium copper chlorophyllin, a green food colorant, were analysed by high-performance liquid chromatography (HPLC) using diode-array detection (DAD) and mass spectrometry (MS). Some of the constituents were identified using authentic standards, whereas others were identified tentatively based on their absorption spectra and mass data. The composition of three of the samples was very similar, whereas the other two were quite different. In the three former samples, the three largest peaks could be assigned to Cu chlorin e₆, Cu chlorin p₆, and Cu isochlorin e₄. In one of the two other samples, these three compounds were also among the largest peaks, whereas Cu chlorin e₆ was a small peak in the last sample and Cu chlorin p₆ was absent altogether. Porphyrins were also present in the samples, while except in one of the samples chlorins derived from chlorophyll b were largely absent.Industrial relevanceSodium copper chlorophyllin is a green food colorant made from chlorophyll. Sodium copper chlorophyllin is made by saponifying chlorophyll and coppering the resulting product. This processing leads to a complex mixture of compounds. An analytical method was developed that can be used to identify many of these compounds and show the extent of coppering and degradation of sodium copper chlorophyllin, which may be used industrially to optimize the production of sodium copper chlorophyllin.     

Volatile compounds in uninoculated and inoculated table olives with Lactobacillus plantarum (Olea europaea L., cv. Moresca and Kalamata)

Table olives' flavour plays an important role in consumer's acceptability and it depends on various factors such as varieties, intrinsic characteristics, ripening of fruit and processing technologies. Flavour biogenesis is also influenced by addition in brine medium of lactic acid bacteria as inoculants, which reduce spoilage risks and improve sensory characteristics. In this work, flavour profiles of uninoculated and inoculated table olives with Lactobacillus plantarum (cv. Moresca and Kalamata) have been analytically characterised and compared. Twenty-one volatile compounds comprise alcohols, aldehydes, ketones, esters as well as acids formed during Greek-style olive fermentation (3 months brining after) have been characterised by gas chromatography and GC/mass spectrometry. Very high contents of ethanol and appreciable amounts of ethyl acetate, isobutanol, 2-butanone, 1-propanol and 1-hexanol were revealed in all samples with a significant increase in inoculated samples with respect to uninoculated ones. Also 1-butanol, 3-pentanol, 3-hydroxy-2-butanone, cis-3-hexen-1-ol and 2-butanol which were present in lower amounts, disclosed a meaningful increase in inoculated samples of both varieties, especially in Moresca inoculated sample. Acetic acid, isopentanol, 2-pentanol, propyl acetate, ethyl propanoate and 4-penten-1-ol showed a significant increase in inoculated Kalamata sample. These results showed that inoculation of brine medium with lactic acid bacteria starters significantly influenced aroma profiles of both varieties, in particular an increase in concentration of various flavour compounds has been revealed in inoculated table olives.     

叶绿素及衍生物研究进展与护绿工艺分析

针对绿色果蔬在加工中裉色和变色问题,将近年来叶绿素褪色机理及护色技术研究进展作了综合分析。结果表明,脱镁叶绿素a,b,焦脱镁叶绿素a,b及脱镁叶绿酸a,b的形成,是造成果蔬色劣化的原因。目前在护绿处理上普遍采用了固色、染色、配色技术。从研究前景上看：1）叶绿素降解机理有待深化;2）金属离子护色方法需有国家标准;3）生物技术的发展将为护绿提供新途径。     

Determination of the volatile profile of stoned table olives from different varieties by using HS-SPME and GC/IT-MS

BACKGROUND: The volatile composition of alcaparras stoned table olives produced from five of the most representative olive cultivars (cv. Cobrançosa, Madural, Negrinha de Freixo, Santulhana and Verdeal Transmontana) from the Trás‐os‐Montes region (north‐east of Portugal) was analytically characterised using headspace–solid phase microextraction/gas chromatography–ion trap–mass spectrometry. RESULTS: Overall, 42 volatile compounds were identified, belonging to distinct chemical classes: 15 aldehydes, seven esters, five alcohols, five sesquiterpenes, four norisoprenoids derivates, three monoterpenes, o ne ketone and two alkenes. Aldehydes were the major chemical class identified in all olive cultivars studied (more than 74% of all the volatile compounds identified). Hexanal, phenylacetaldehyde and (E,E)‐2,4‐heptadienal were the major volatile compounds identified. CONCLUSIONS: It was possible to discriminate the results obtained from the volatile profile of the five olive cultivars by using principal component analysis. Both qualitative and quantitative fractions of alcaparras table olives were influenced by olive cultivar, which confers a single aroma. This fact certainly influences consumer preference and acceptability towards a specific olive cultivar. Copyright © 2011 Society of Chemical Industry     

Physicochemical, microbiological, and organoleptic profiles of Greek table olives from retail outlets

The physicochemical, microbiological, and organoleptic profile of different commercial table olive products from retail outlets was studied. Average pH values were 4.00, 3.96, and 4.31 for Spanish-style green, naturally black, and dry-salted olives, respectively, while salt content was 6.21, 7.34, and 8.00% for the same commercial products. Mean values for titratable acidity were 0.53 and 0.63% (wt/vol) for green and naturally black olives. In general, mean values for pH, titratable acidity, and salt content were in accordance with the requirements established by the International Olive Oil Council (IOOC) for the trade of table olives, although considerable variation was observed within individual olive samples. Salt content of dry-salted olives did not meet the minimum limit of 10% established by the IOOC. The dominant microbiota consisted of lactic acid bacteria and yeasts. Their population was less than 10(9) CFU ml(-1), as stipulated by the IOOC standard for fermented olives held in bulk in a covering liquid. These microorganisms come from the natural microbiota found in spontaneous fermentations and impose no risk to human health. No enterobacteria, pseudomonads, Bacillus cereus, or Clostridium perfringens were detected in any of the samples given the physicochemical characteristics found. The organoleptic profile varied greatly according to processing style and commercial preparation. Green olives had more uniform sensory characteristics than naturally black and dry-salted olives. The most important attributes that influenced the judgment of the panelists were salt content and crispness of the olives.     

Physico-chemical properties of Azizi' green pickled olives as affected by alkali process.

This work was carried out to study the effect of lye treatment at different concentrations (1.0, 2.0 and 2.5%) on some physical-chemical changes of green table olive 'Azizi' cultivar during fermentation process. Results indicated that lye treatment at 1% and 2% using sodium hydroxide were the more suitable concentration for processing green table olive 'Azizi' cultivar under Egyptian condition, where the quality in texture, colour, flavour and appearance was recorded. Statistical analysis revealed that there were significant differences in pH, NaCl content and acidity of green olive during the fermentation period as affected by lye treatment. A positive correlation was found between the sensorial properties of pickled olives.     

Mineral content and sensory characteristics of Gordal green table olives fermented in chloride salt mixtures

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.