Green Table Olives Research Articles

Preservation of Manzanilla Aloreña cracked green table olives by high hydrostatic pressure treatments singly or in combination with natural antimicrobials

High hydrostatic pressure (HHP) treatments (singly or in combination with natural antimicrobials) were tested for stabilization of Manzanilla Aloreña seasoned olives stored at 25 °C. HHP (5 min) was highly effective on yeast populations at 300 MPa or higher. No viable yeasts were detected in samples treated at 400 MPa for up to three months. Low levels of endospore-forming bacteria were always detected after HHP treatments. Addition of nisin to the brines reduced bacterial counts by 1.4 log cycles but it had no effect on yeasts when tested singly or in combination with HHP treatment (400 MPa, 5 min). Thyme oil had almost no effect on yeast concentrations, but rosemary oil reduced yeast viable counts progressively during storage. Essential oils in combination with HHP (400 MPa, 5 min) significantly (p < 0.05) reduced the concentrations of aerobic mesophilic bacteria. Low-salt brined olives purged with N2 or supplemented with ascorbic acid and then pressurized for 5 min at 450 or 550 MPa were preserved for up to 5 months without spoilage, suggesting that the NaCl content in brines of packed Manzanilla Aloreña table olives could be reduced considerably by application of HHP as a stabilization treatment.

Quality Improvement of Green Table Olive cv. ‘Domat’ (Olea europaea L.) Grown in Turkey Using Different De-Bittering Methods

The most basic step in table olive production is de-bittering. Olives contain bitter flavor compounds such as oleuropein, and their presence precludes the consumption of fresh fruits. Oleuropein can be removed by natural methods (e.g., using tap water) or by applying various chemicals (e.g., lye). Chemicals affect the organoleptic and nutritional qualities of the olive fruit. The aim of this study was to improve the quality of naturally fermented ‘Domat’ cultivar green table olives using different de-bittering methods (by scratching, using 1% lye and using tap water). The lye pre-treatment negatively affected the nutritional, organoleptic and color qualities of the olives. In all of applications, the best color stability was obtained in the olives that were de-bittered using the scratching method.

Fate of Escherichia coli O157:H7, Salmonella Enteritidis and Listeria monocytogenes during storage of fermented green table olives in brine

The survival of Escherichia coli O157:H7, Salmonella Enteritidis and Listeria monocytogenes during the storage of fermented green table olives cv. Halkidiki in brine was studied in parallel with the evolution of lactic acid bacteria (LAB), yeasts and pH. The olives were previously fermented with a starter culture (a potential probiotic strain of Lactobacillus pentosus B281 – starter process) or with the indigenous microbiota (control). After the end of fermentation, olives were placed in brine, inoculated with a cocktail of 5 strains of E. coli O157:H7, 5 strains of L. monocytogenes and 4 strains of S. Enteritidis, with a final concentration in the brine of ca. 7.0 log CFU/ml, and subsequently packaged in polyethylene pouches and stored at 20 °C. The population of E. coli O157:H7 reduced gradually and was detected in the brine until the 27th day of storage in both cases (i.e., starter and control process), and on olive fruits until the 19th and 16th days of storage in the starter and control process, respectively. S. Enteritidis population showed also a decrease and it was detected until the 21st day of storage in both brine and olive fruits in both cases. The population of L. monocytogenes declined during storage and it was detected until the 31st day of storage in both brine and olive fruits in both cases, showing a longer survival period in comparison to the other two studied pathogens. The presence of the potential probiotic starter did not affect the pathogen survival. The results demonstrated that even though the growth of the pathogenic strains was not supported, they may survive for a long period in a stressful environment of a fermented product with low pH value (4.2) and high salt concentration (6.0%). These results are a valuable contribution to risk assessment studies related to ready to eat foods in general.

Storage of mechanically harvested Manzanilla olives under controlled atmospheres

The mechanical harvesting of Manzanilla fruit destined for Spanish-style green table olives has never been developed on an industrial scale because of the brown spots formed on the bruised areas during olive transportation from the groves to the olive factories. In this study, the use of several inert atmospheres to preserve mechanically harvested olives was investigated. Nitrogen, argon and nitrogen spiked with SO2 (0.01–0.05%) prevented the formation of brown spots on the bruised areas for at least 6h but the browning reactions rapidly progressed after the inert atmosphere was released. Olives were also immersed in several chemical solutions (0.5% ascorbic acid, 0.3% NaOH, 0.05% SO2, and 1% glycerol) before and after the postharvest storage in nitrogen with the aim of reducing oxygen diffusion into the fruit. Only the use of glycerol as a coating layer before the nitrogen atmosphere showed slightly good results. Moreover, it has been demonstrated that the browning reactions in bruised olives were developed due to the oxidation of oleuropein without the requirement of any previous hydrolysis reactions of this polyphenol. The decrease in oleuropein and increase in darkening of the bruised areas of olives preserved in nitrogen and re-exposed to air was also caused by enzymatic reactions.

Spanish‐style green table olive shelf‐life

SummaryChanges in the physicochemical and sensory characteristics of commercial whole, pitted and stuffed with pepper, garlic or anchovy paste Spanish‐style green table olives of the Gordal, Manzanilla and Hojiblanca cultivars were studied during a three‐year period. No olives developed any spoilage during this period, and at the end of it, all presentations were classified as ‘extra’ according to the sensory evaluation methodology issued by the International Olive Council. Throughout the shelf‐life, surface colour index and firmness of the olives degraded in accordance with a first‐order kinetics, while a gradual browning of the cover brines was observed; however, products added with ascorbic acid maintained a stable colour, while those with calcium content showed reduced firmness degradation. No significant changes in most of the sensory characteristics were observed by the panel test during shelf‐life and only slight changes in firmness, and surface colour were noticed in samples with significant differences in these attributes when measured instrumentally.

Sensory evaluation and consumer perception of some commercial green table olives

PurposeThe objective of this study is to evaluate the physico‐chemical and sensorial characteristics of some commercial green table olives. Also, it seeks to elaborate the sensorial background of consumer preferences of different green table olives.Design/methodology/approachFour green table olive samples (Çelebi, Domat, Kaba, and Ayvalık) commonly consumed in Turkey were chosen and collected from a local producer. Dimensional measures, salt content, pH value, oil content, titrable acidity, L value, a* value, b* value and texture of samples were assessed by the AOAC methods. A panel described and measured the appearance (greenness, yellowness, globeness), aroma (fresh olive, vinegary, soapy, musty), flavour (sour, salty, bitter, hay, oily) and texture properties (firmness, flesh/stone adherence, fibrousness, watery). In addition, 50 consumers evaluated hedonic values.FindingsThe salt content, pH value, oil content, titrable acidity, L value, a* value, b* value and texture of samples were found to following values 2.91‐5.46 percent, 2.80‐3.97, 4.67‐18.71 percent, 0.59‐1.40 percent, 49.96‐69.56, 1.35‐17.91, 19.57‐45.47 and 434.1‐895.7 g. Although prepared with the same technique, many properties of the olives were found different. This difference affected consumer preference and buying intentions as well.Research limitations/implicationsThe paper provides scientific data for researchers to design similar sensory descriptive analyses for different table olive samples.Originality/valueThe paper is helpful both to consumers and traders to determine the proximate and sensory attributes of commercial green olive samples.

Characterization of lactic acid bacteria from naturally-fermented Manzanilla Aloreña green table olives

Manzanilla Aloreña (or Aloreña) table olives are naturally fermented traditional green olives with a denomination of protection (DOP). The aim of this study was to search for lactic acid bacteria (LAB) with technological properties of interest for possible inclusion in a starter or protective culture preparation or also as probiotics. A collection of 144 LAB obtained from Aloreña green table olives naturally-fermented by four small-medium enterprises (SMEs) from Málaga (Spain), including lactobacilli (81.94%), leuconostocs (10.42%) and pediococci (7.64%) were studied. REP-PCR clustering and further identification of strains by sequencing of phes and rpo genes revealed that all lactobacilli from the different SMEs were Lactobacillus pentosus. Pediococci were identified as Pediococcus parvulus (SME1) and leuconostocs as Leuconostoc pseudomesenteroides (SME1 and SME4). Genotyping revealed that strains were not clonally related and exhibited a considerable degree of genomic diversity specially for lactobacilli and also for leuconostocs. Some strains exhibit useful technological properties such as production of antimicrobial substances active against pathogenic bacteria such as Listeria monocytogenes, Bacillus cereus, Staphylococcus aureus, Streptococcus mutans and Salmonella enterica, utilization of raffinose and stachyose, production of bile salt hydrolase, phytase and haeme-dependent catalase activities, growth at 10 °C and in the presence of 6.5% NaCl, good acidifying capacity and also resistance to freezing. However, none of the isolates showed protease or amylase activity, and also did not exhibit biogenic amine production from histidine, ornithine, cysteine or tyrosine. On the basis of data obtained, selected strains with potential traits were tested for their survival at low pH and their tolerance to bile salts, and the survival capacity demonstrated by some of the analysed strains are encouraging to further study their potential as probiotics.

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. 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.

Quality evaluation of different typical table olive preparations (cv Nocellara del Belice)

Commercially available green table olives of the Nocellara del Belice cultivar were processed in 26 companies. Three different processing conditions were used to obtain olive debittering: natural fermentation, “Castelvetrano” (a typical west Sicilian method) and cracked olives. The green olives packed into 200-500 mL glass jars were analyzed for physico-chemical characteristics that revealed statistical differences among the three debittering methods and a great difference among the samples, reflecting a low level of standardization achieved in these fermented products. The results showed an influence of the treatments on all physico-chemical parameters with the exception of total polyphenol content and lightness (L*) for which no significant differences were found. The average pH in the brine samples was under the hygienic limit of 4.5 with the exception of Castelvetrano olives which showed a higher pH values. The salt concentration of the brine samples appeared lower than the commercial limit according to the table olive trade standards. The brine samples were also analyzed for some microbiological parameters. Not all the samples showed acceptable commercial standards, because Clostridium perfringens, Staphylococcus aureus and coliform bacteria were detected in a few samples.

Suitability of a probiotic Lactobacillus paracasei strain as a starter culture in olive fermentation and development of the innovative patented product “probiotic table olives”

Probiotic bacteria are generally available for consumers as concentrated preparations or incorporated in milk-based foods. Due to an increased interest of the market for probiotic foods as well as to meet a demand of industry for innovation, a new kind of probiotic food has been developed using table olives as a carrier. Green table olives, produced according to the Spanish-style, are obtained by a fermentation which can be carried out by spontaneous microflora, even if the use of starter cultures is desirable to obtain a more controlled process. In this regard, the selected strain Lactobacillus paracasei IMPC 2.1 of human origin was used in the dual role of starter and probiotic culture, and here we describe the different aspects which have been evaluated and solved to utilize that strain for the development of a new table olive-based probiotic food. These aspects include selection of the strain on the basis of its probiotic properties, molecular characterization, compatibility with the carrier food, and efficacy as starter. The final product meets commercial and functional requirements throughout its shelf-life.

Effects of salt mixtures on Spanish green table olive fermentation performance

This work investigates the effect of sodium, potassium, and calcium chloride salts on the performance of Spanish green table olive fermentation using a simple centroid mixture design. The presence of calcium chloride hindered the diffusion of all sugars and delayed the period required to reach their respective maximum concentrations in brines. Such effects can prevent tumultuous processes and gas pocket spoilage. Acetic acid was present at low concentrations in all treatments but was not generated during fermentation. The production rate of lactic acid was either decreased or delayed by the presence of calcium chloride but adequate final conditions were always reached. The chemometric analysis classified treatments into groups according to the presence of calcium chloride and disclosed a stimulating effect of potassium on lactic acid production. Therefore, these techniques can be a useful tool to investigate olive fermentation performance. According to the results, acceptable Spanish green table olives can be produced using salt mixtures, with the subsequent reduced sodium content in the final products. The results obtained in this study could also be of interest for other fermented vegetables.

Use of selected autochthonous lactic acid bacteria for Spanish-style table olive fermentation

The present work presents a successful attempt to achieve an enhanced and more predictable fermentation process in Spanish-style green olive technology by selection and use of autochthonous starter cultures. During the first phase of this work, two Spanish-like fermentations of green table olives of cultivar (cv) “Nocellara del Belice”, coming from irrigated and not irrigated fields, were monitored, in order to highlight the best agricultural conditions for drupe production and to isolate lactic acid bacteria strains with relevant technological properties. Among 88 identified isolates, one Lactobacillus pentosus strain showed remarkable biochemical features and high acidification rate in synthetic brine. In the second phase, the selected strain was used as starter culture in three different trials to establish the best conditions for its use. Microbial counting, as well as starter tracking by M13 RAPD-PCR, reflected the optimal adaptation of the strain to the environment. Spontaneous fermentation needed a 14-day long lag phase to reach the same population as the inoculated trials. Moreover, sensory traits of table olives obtained with adjunct culture showed better characteristics compared to those processed in the other trials, in particular concerning the presence of off-odours.

Identification and quantification of metallo-chlorophyll complexes in bright green table olives by high-performance liquid chromatrography-mass spectrometry quadrupole/time-of-flight.

Five different samples of table olives, two regular Spanish table olives and three "bright green table olives", have been analyzed by HPLC-MS/MS to determine their pigment profile. Typical pigment profiles of almost all table olives show primarily chlorophyll derivatives lacking metals (e.g., pheophytin a/b and 15(2)-Me-phytol-chlorin e(6)). Bright green table olives have a unique profile including metallo-chlorophyll complexes (Cu-15(2)-Me-phytol-chlorin e(6) with 26-48% and Cu-pheophytin a with 3-18%) as their major pigments. New tentative structures have been identified by MS such as 15(2)-Me-phytol-rhodin g(7), 15(2)-Me-phytol-chlorin e(6), 15(2)-Me-phytol-isochlorin e(4), Cu-15(2)-Me-phytol-rhodin g(7), Cu-15(2)-Me-phytol-chlorin e(6), and Cu-15(2)-Me-phytol-isochlorin e(4), and new MS/MS fragmentation patterns are reported for Cu-15(2)-Me-phytol-rhodin g(7), Cu-15(2)-Me-phytol-chlorin e(6), Cu-pheophytin b, Cu-pheophytin a, Cu-pyropheophytin b, and Cu-pyropheophytin a. The presence of metallo-chlorophyll derivatives is responsible for the intense color of bright green table olives, but these metallo-chlorophyll complexes may be regarded as a "green staining" defect that is unacceptable to consumers.

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.

Microbial quality and yeast population dynamics in cracked green table olives’ fermentations

Cracked green table olives, from the Manzanilla variety, are a fermented food produced and consumed in Portugal. The objective of the present work was to study the microbiological characteristics and yeast population evolution during the fermentation of cracked green olives. The predominant microorganisms were yeasts while lactic acid bacteria were not detected and a clear decrease of the mould population was observed. At the end of the fermentations, no viable counts of Enterobacteriaceae were found. Yeast isolates were identified by the 5.8S rRNA-ITS region restriction analysis and by sequencing the D1/D2 region of the 26S rRNA gene. During the initial phases of the fermentations a great diversity of yeasts was observed. However, as the processes evolved the biodiversity decreased with the fermentative yeasts Citeromyces matritensis, Zygotorulaspora mrakii and Saccharomyces cerevisiae becoming the dominant species. The presence of these fermentative yeasts at the end of the production process is associated to a risk of spoilage. The results obtained represent a first attempt towards the comprehension of the microbiota of this type of “Natural olives” that constitute an important component of the Mediterranean diet.

Annotated Genome Sequence of Lactobacillus pentosusMP-10, Which Has Probiotic Potential, from Naturally Fermented Aloreña Green Table Olives

Lactobacillus pentosus MP-10 was isolated from brines of naturally fermented Aloreña green table olives. MP-10 has potential probiotic traits, including inhibition of human pathogenic bacteria, survival at low pH (1.5), and bile salt tolerance (3%). Here, we report for the first time the annotated genome sequence of L. pentosus.

Yeast dynamics during the fermentation of brined green olives treated in the field with kaolin and Bordeaux mixture to control the olive fruit fly

The yeast microbiota associated with naturally fermented and inoculated green table olives, differently treated in the field with non-conventional repellent and antiovipositional products in the control of Bactrocera oleae, was analysed using a combination of culture-dependent and -independent molecular fingerprinting. The routine yeast isolation gave rise to 118 strains, whose identification was performed by PCR-RFLP of the internal transcribed spacer (ITS) regions. Total DNA was extracted directly from the brine throughout fermentation by means of an experimental protocol that included the removal of Taq polymerase inhibitors. Denaturing Gradient Gel Electrophoresis (DGGE) of 26S rRNA gene PCR amplicons highlighted the yeast community. Comparison of both culture-dependent and independent methods indicated that the yeast species Saccharomyces cerevisiae, Wickerhamomyces anomalus, Candida diddensiae and Issatchenkia orientalis were dominant during fermentation despite the addition of the Lactobacillus plantarum starter used in brining. The resultant isolated species were unaffected by treatments in field, except for C. diddensiae whose growth was delayed by kaolin.

Effect of Cultivar on Sensory Characteristics, Chemical Composition, and Nutritional Value of Stoned Green Table Olives

The effect of olive cultivar on sensory characteristics, chemical composition, and nutritional value of traditional stoned green table olives “alcaparras” was studied. The most representative cultivars from Tras-os-Montes region, Portugal (Cv. Cobrancosa, Madural, Negrinha de Freixo, Santulhana, and Verdeal Transmontana) were studied. The results showed that, regardless the cultivar, water was the main constituent with values greater than 70%, followed by fat that varied between 12.5% and 20.1%. Carbohydrates amount was greater in Cv. Madural (9.2%) and those produced from Cv. Cobrancosa had higher level of nitrogenous compounds, with 1.4%. Ashes contents of table olives varied from 1.6% to 1.9%, without significant differences among cultivars. Moreover, 100 g of “alcaparras” provided an energetic value between 154 and 212 kcal for Cv. Madural and Verdeal Transmontana, respectively. Oleic acid was the main fatty acid detected (higher than 66.9%), followed by palmitic acid (10.8–13.3%) and linoleic acid (2.7–10.3%). A linear discriminant model was established based on the “alcaparras” table olives fatty acids profile. Three fatty acids (C16:0, C18:0, and C18:3) and total saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids contents allowed distinguishing between the five olive cultivars studied, with overall sensitivity and specificity of 100%. The total content of vitamin E of the table olives varied from 3.5 and 6.0 mg/kg (for Cv. Santulhana and Negrinha de Freixo, respectively), being α-tocopherol the most abundant. The consumer’s panel showed higher preference for the table olives of Cv. Verdeal Transmontana and Negrinha de Freixo, while Cv. Madural was negatively characterized in all the descriptors evaluated.

Exploring the yeast biodiversity of green table olive industrial fermentations for technological applications

In recent years, there has been an increasing interest in identifying and characterizing the yeast populations associated with diverse types of table olive elaborations because of the many desirable technological properties of these microorganisms. In this work, a total of 199 yeast isolates were directly obtained from industrial green table olive fermentations and genetically identified by means of a RFLP analysis of the 5.8S-ITS region and sequencing of the D1/D2 domains of the 26S rDNA gene. Candida diddensiae, Saccharomyces cerevisiae and Pichia membranifaciens were the most abundant yeast species isolated from directly brined Aloreña olives, while for Gordal and Manzanilla cultivars they were Candida tropicalis, Pichia galeiformis and Wickerhamomyces anomalus. In the case of Gordal and Manzanilla green olives processed according to the Spanish style, the predominant yeasts were Debaryomyces etchellsii, C. tropicalis, P. galeiformis and Kluyveromyces lactis. Biochemical activities of technological interest were then qualitatively determined for isolates belonging to all yeast species. This preliminary screening identified two isolates of W. anomalus with interesting properties, such as a strong β-glucosidase and esterase activity, and a moderate catalase and lipolytic activity, which were also confirmed by quantitative assays. The results obtained in this survey show the potential use that some yeast species could have as starters, alone or in combination with lactic acid bacteria, during olive processing.

Treatment of wastewaters from the green table olive packaging industry using electro-coagulation

The application of electro-coagulation technology for the pre-treatment (or partial-depuration) of the wastewaters from the green table olive packaging industry was investigated. Different electrode materials and operational conditions were examined. The highest depuration rate was obtained using aluminum in the anode and iron in the cathode, current density of 25 mA cm −2 and distance between electrodes of 0.6 cm. In this case, after 50 min of treatment, chemical oxygen demand (COD) elimination reached 40% and most of the initially present phenols and color of the solutions were removed; the pH was also neutralized. Per cubic meter of wastewater, the total consumption of electricity was 0.76 kWh and the aluminum loss in sacrificial electrode 2.15 g. The treated liquid consisted almost entirely of a solution of lactic and acetic acids, which could be reused in packing or treated by conventional depuration plants.